Urgent: Bird hatchling identification

Urgent: Bird hatchling identification

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Yesterday evening I found this baby bird in one corner of my house's verandah on the floor. I picked it up and placed it safely in a tray hoping that tomorrow morning its parents will find it (actually I initially suspected it to be a sparrow hatchling). When I saw it today morning I found that it is probably a bird of prey. As you can notice the large long beak and claws. I'm really confused now what to do with it. Please suggest something.


  • I live in Uttar Pradesh, India.

  • Its relatively plain where I live. (No mountains or lake nearby)

  • Temperature: 35-20 degrees Celsius

  • Added a photo for size estimation

As you've pictured this is a fledgling that you found which has a mixture of adult feathers and immature feathers. This indicates that it flew to your location, and a nest is nearby. You should either attempt to find the nest, or just leave the fledgling alone and let it make its own way home as indicated in this online resource.

Fledglings are juvenile birds who have a mix of fuzzy down and adult feathers and are learning to fly. You may come across them hopping along on the ground, perching on low-hanging branches, or hiding under bushes, but as long as they're healthy, just let them be.

Note: Fledglings are often “rescued” from their natural environment when they don't need to be.

Patuxent Wildlife Research Center

The conservation and management of migratory bird populations has been the focus of Patuxent research and monitoring activities for decades. Patuxent scientists remain at the forefront of research activities exploring a wide variety of issues relevant to migratory bird conservation and developing new statistical approaches that expand the insights possible from ecological studies conducted by scientists from around the world. In addition to its research accomplishments, Patuxent hosts operational programs such as the US Bird Banding Laboratory and North American Breeding Bird Survey. Both programs maintain important data resources that are widely used to document the status, trends, seasonal movements, and other aspects of avian ecology and are essential for managing migratory bird populations.

Browse Migratory Birds science related to:

Bird Banding Laboratory

The Bird Banding Laboratory (BBL) is an integrated scientific program established in 1920 supporting the collection, archiving, management and dissemination of information from banded and marked birds in North America. This information is used to monitor the status and trends of resident and migratory bird populations. Because birds are good indicators of the health of the environment, the.

Defining synchronous hatching

Synchronous emergence of neonatal turtles from the nest is well documented ( De Pari 1996 Tucker 1997, 1999 Nagle et al. 2004), although it is not ubiquitous (e.g., Kolbe and Janzen 2002), with many marine turtles hatching throughout the day but delaying emergence until dusk or night ( Bustard 1967 Mrosovsky 1968, 1980). Indeed, social facilitation behavior of hatchling green turtles (Chelonia mydas) occurs during emergence from the nest ( Carr and Hirth 1961). But such emergence behavior should not be confused with synchronous hatching, which refers to coordinated departure from eggs of fully formed embryos (i.e., hatchlings). Experimental evidence of environmentally cued hatching in turtles has focused on three freshwater species, where thermal variability in the shallow nests is well established ( Thompson 1988). Pig-nose turtles (Carettochelys insculpta) can hatch spontaneously, embodying the traditional view of synchronous hatching as described above for various anurans. Two other species of freshwater turtle have displayed some capabilities to hatch synchronously by responding to developmental and hatching cues of clutch mates: E. macquarii can hatch synchronously under warmer incubation temperature regimes ( Spencer et al. 2001), and the painted turtle, Chrysemys picta, was unable to hatch synchronously in experimental protocols, despite clearly adjusting hatching times ( Colbert et al. 2010). Spontaneous or synchronous hatching in species that hatch early or accelerate development (as opposed to delaying hatching) is difficult to achieve, thus for the remainder of this review the term “synchronous hatching” should be understood to include any response of an embryo to the developmental stage or hatching behavior of clutch mates, which may not necessarily result in spontaneous hatching, but does result in the adjustment of incubation times. Such synchronous hatching occurs in precocial birds ( Vince and Chinn 1971) and turtles ( Spencer et al. 2001, Colbert et al. 2010).


Altricial – describes birds that hatch with little to no downy feathers and are relatively immobile, such young must be fed by adults and need time to develop before leaving the nest. Most passerines are altricial. Altricial is the opposite of precocial. Eagles are considered semi-altricial.

Alula – Also called bastard wing, this projection on the front edge of the wing typically has three to five feathers which can be spread when flying slowly to keep the bird from stalling. The alula is the first digit, anatomically analogous to the thumb.

Anklet – Part of the equipment worn by captive birds of prey, the anklet is a leather band that fastens around the leg. Also referred to as bracelet. Jesses attach to the anklet.

Asynchronous – Describes hatching in a clutch of eggs that occurs over a period of several days rather than all the eggs hatching together

Axillary – the area under the wing, next to the body

Bate – sudden movement of a raptor off a handler’s arm or its perch.

Bergmann’s Rule – Bergmann’s rule states that among mammals and birds, individuals of a particular species in colder areas (further from the equator) tend to have greater body mass than individuals in warmer climates (closer to the equator). One example is that bald eagles are larger in Alaska than those found along the Gulf Coast of the United States.

Bi-colored beak – describes a beak of two colors Immature bald eagles have a bi-colored beak which is dark, blue-black and lighter toward the base. As juvenile bald eagles mature the beak color gets lighter from the base outward, gradually becoming the light yellow of the adult bald eagle.

Blood feather – a new feather still growing in that has nerves and blood supply in the shaft. A blood feather has not yet hardened and is more prone to breakage. Sometimes called a pin feather.

Booted eagles – one of the four major groups of eagles Booted eagles have feathers on their entire leg, including on their tarsometatarsi, up to their toes. Golden eagles are part of the booted eagle family. Also called True eagles.

Branching – a behavior common in eaglets just before fledging. In branching, eaglets move from the nest to a branch and flap their wings and jump off the branch. This behavior serves to strengthen flight muscles and acclimate the eaglet to life outside the nest.

Brood patch – a bare area of skin that develops on adult birds who are incubating eggs that allows blood vessels in the skin more direct contact with the egg to maintain it at body temperature

Bumblefoot – a condition typified by sores on the bottom of a bird’s foot caused by infection and inflammatory reaction It is somewhat analogous to bedsores in humans and can be caused by inappropriate or insufficient variety of perches, poor nutrition, obesity and/or inactivity or a compromised immune system. Captive birds are more susceptible to bumblefoot than non-captive birds.

Buteo – genus of hawks typified by long, broad, rounded wings and shorter, rounded tails includes red-tailed, rough-legged, broad-winged and red-shouldered hawks that are often seen soaring with wings and tails spread

Carpal – referring to the wrist area

Carrion – dead and decaying flesh of animals may serve as food for scavengers or opportunistic predators

Carnivore – an animal that derives its energy and nutrient requirements from a diet consisting of animal tissue, whether through predation or scavenging

Cere – fleshy region at the base of the beak that surrounds the nostrils. See Photo

Cervical vertebrae – vertebrae (bones) in the neck region. Raptors have 14 cervical vertebrae that allow them to turn their necks 180 degrees or more. In contrast, humans have only 7 cervical vertebrae and can rotate their heads just 70-90 degrees in either direction.

Cloaca – Posterior opening common to the intestinal, urinary and generative systems. In birds, also called the vent.

Cloacal kiss – in copulation, when male and female cloacas touch and sperm is transferred from male to female

Clutch – group of eggs laid in a given breeding season

Complete migration – all individuals of a species leave the breeding range during nonbreeding season

Copulation – mating, act that accomplishes the transfer of sperm from male to female see cloacal kiss

Congress – a term that refers to a large gathering of eagles. Also referred to as a convocation.

Coot – part of the rail family small, all black plumage a favorite food of bald eagles especially during fall migration

Coping – trimming or shaping the beak or talons Coping is often necessary for captive birds of prey that have a nutrient rich diet and may incur less wear on their beak than wild birds.

Coverts – contour feathers found on body, usually named for their location on the bird, e.g. primary coverts

Crepuscular – active at dawn and dusk

Crop – widening in the esophagus where a hawk, eagle, falcon or vulture can store food sometimes referred to as the craw

Deck feathers – the two central tail feathers

Dihedral – A wing position used by some birds when soaring. A dihedral resembles a V, with wings tips raised from horizontal. e.g. Turkey vultures commonly soar in a dihedral wing position.

Diurnal – describes an animal or bird that is active during the day Eagles and many raptors are diurnal, indicating that they hunt during the day.

Eaglet – a young eagle, typically describes an eagle some days after hatching (hatchling) up to the period before the first flight (fledgling)

Egg tooth – Hatchling eaglets have a special notch on their beak to facilitate pipping. This pip tooth or egg tooth falls off several days after hatching.

Endangered species – a species that has been identified as under threat of extinction or extirpation In the United States, the US Fish and Wildlife Service maintains an official list of species that are considered endangered and threatened or of special concern. Internationally, the International Union for the Conservation of Nature (IUCN) maintains listings of more than 49,000 species, subspecies and varieties of flora and fauna and places each in a category based on the level of threats that species is facing in the wild.

Extinction – the complete loss of a species from the planet

Extirpation – the loss of a species from a particular part of its natural range e.g The bald eagle was nearly extirpated from the continental US. Populations in Alaska and Canada remained healthy even while bald eagles were rare in the lower 48 states.

Eyrie – An eagle nest site, an eyrie is typically elevated high in a tree or on a cliff ledge.

Facial disc – a concave circle of feathers on the face of owls and harriers that help the bird to locate prey by directing sound to the ears

Falcon – a member of the family Falconidae and the genus Falco, characterized by long pointed wings, dark eyes and medium to long tails along with the other raptor characteristics of hooked beaks, sharp talons, and keen eyesight. Falcon species include Peregrine Falcons, Kestrels, Merlins and Prairie Falcons and many others.

Falconry – the ancient sport of hunting with a trained raptor

Feaking – The act of rubbing the beak against a surface for cleaning or maintaining beak shape, often done after eating.

Fish eagle – eagles that feed primarily on fish, one of the four major groups of eagles, also called sea eagles

Fledge – the act of a young bird taking its first flight from the nest

Fledgling – An immature bird who has flown at least once but who remains under the care of adult birds.

Flight feathers – consist of the wing feathers (the primaries and secondaries collectively called remiges) and the tail feathers (retrices)

Fret Marks – lines across the feathers which develop as a result of the bird being malnourished, ill or stressed while those feathers were growing also called stress marks/bars

Genus – The taxonomic classification just above species a group of species exhibiting common characteristics Golden eagles are in the genus Aguila. Bald eagles are in the genus Halieaatus.

Gizzard – part of the stomach in many birds that contains small stones or gravel which is used to break down food mechanically. Raptors do not use the gizzard to digest their food. Instead, raptors digest food with powerful stomach acids.

Glide – coasting downward in flight without flapping. It is the opposite of Soar.

Hackles – feathers on the back of the head, raised when the bird is in a stressed or aggressive state

Hallux – the largest toe, which points backwards in most bird species, assists in perching

Hatchling – refers to bird in the few days just after hatching, or breaking out of the eggshell

Harpy eagles – refers to a particular species of eagle, Harpia harpyja, found in Central America Also refers to one of the four major groups of eagles around the world. The harpy eagle group also includes the Papuan Eagle, Harpyopsis novaeguineae, of New Guinea.

Home range – area that an animal may use to find food usually larger than their breeding territory and not defended as such

Hopscotch – describes a particular migration pattern in which the northern most birds migrate farther south than some year round residents of the same species. As an example, red-tailed hawks in Minnesota may stay year round, while some of the birds from Canada migrate to an area south of Minnesota.

Hovering – flap flying in place hoveringis very energy intensive and most commonly seen in kestrels and rough-legged hawks. (contrast with Kiting)

Imping – the process of repairing a flight feather by joining the broken feather to an intact feather (which may be a previously molted feather) by joining the two feather shafts

Imprinting – describes a psychological process where a young bird or animal identifies with a figure present early in life birds raised by humans form inappropriate bonds with humans and may later be unable to form pair bonds with their own species imprinted birds are typically unable to be released to the wild

Irruption – describes sporadic migration which occurs only in some years, usually due to lack of prey availability in typical range

Jess – strap (traditionally leather) that attaches to the anklet of a captive bird of prey. See Photo

Keel – ridge of the breast bone where the flight muscles attach

Kettle – a group of birds using a thermal (rising pocket of air) to gain elevation

Kite or Kiting – flying in one place without flapping (contrast with Hovering)

Leading edge – a term used by bird watchers and others to describe the front edge of the wing

Leash – rope attached to the jess or jess extender on a captive bird of prey the leash is either held by the handler or used to tether the bird to a perch.

Lore(s) – the region between the eyes and nostrils of a bird, reptile or amphibian. See Photo

Lure – a falconry tool that is used to train a bird of prey Food is attached to the lure which is then swung around on a long rope and thrown for the raptor to seize. Lures are typically made of leather cut in the shape of a bird.

Mantle – a behavior of raptors characterized by spreading the wings and tail often to defend food

Mew – an enclosure or housing area for captive birds of prey

Migration – the seasonal movement of animals between breeding and non-breeding ranges

Molt – the natural process of replacing feathers Raptors molt once a year, usually in spring and summer. They tend to molt symmetrically meaning if they lose the third primary on the right, they also lose the third primary on the left. Raptors do not lose all their flight feathers at one time and are never rendered flightless by a molt. It can take up to four years for an eagle to complete a molt.

Morph – a variation with in a species, such as a color morph e.g. Rough-legged hawks have two color morphs, light and dark. Eastern screech owls have two color morphs rufous (reddish) and gray.

Mutes – bodily waste of a raptor that includes urine and feces There are three parts to a mute: fecal – the semi-solid mass, frequently this is dark in color. Urate – white, chalky material – the crystalline uric acid that is the result of protein metabolism. Urine – clear water that flushes the waste from the system.

Nape – the back of a bird’s neck On golden eagles this area exhibits a golden color.

Nest site fidelity – describes the tendency of eagles and some other birds to return to the same nest site each breeding season

Nictitating membrane – also known as “the third eyelid” closes from the interior edge out to the side The membrane cleans and protects the eye. See Photo where membrane is partially covering the eyeball and appears as a cloudy film over the eye.

Nocturnal – describes an animal or bird that is active at night

Opportunistic predator – describes predation pattern of animals that hunt when necessary and scavenge when carrion is available

Ornithology – the study of birds

OspreyPadion haliaetus a raptor that feeds almost exclusively on fish, sometimes called a fish hawk Osprey are able to catch fish in deeper water than bald eagles because they can dive below the surface of the water. An osprey’s toe is reversible, allowing them to grasp their prey with two toes in front and two behind or three toes in front and one behind (as an eagle would grasp).

Partial Migration – some members of a population leave the breeding range during nonbreeding season while others remain in the breeding range year round

Passerine – bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds.

Patagium – the leading edge of the wing between the shoulder and the wrist
In Red-tailed Hawks the dark patagial line is one of the best field marks.

Pellet – indigestible food regurgitated by a bird In the case of eagles, a pellet consists only of fur or feathers. Other raptors, such as owls, also regurgitate bones in their pellet along with the fur of animals they consume. See Photo of an eagle pellet – note no bones in the pellet.

Pipping (pip) – breaking through the eggshell by a hatchling the first break is called a pip. Hatchling eaglets have a special notch on their beak, an egg tooth, to facilitate pipping.

Photo period – the period of daylight in every 24 hours varies seasonally except at the equator. In the northern hemisphere, the photo period is longest on June 21st and shortest on December 21st. For many birds, the timing of biologic processes such as molting and breeding can be triggered by changes in the photo period.

Plumage – refers to the feathers as well as to the color and pattern of a bird’s feathers. Many species may have different plumages based on gender or age.

Precocial – young that are born or hatched with some downy feathers and are mobile and able to flee or defend themselves from predators opposite of altricial, describing young that need time to mature before leaving the nest.

Predator – an animal or bird that hunts and feeds on other living organisms

Preening – grooming of the feathers, pulling the beak down the feather to clean and straighten it preening is a behavior of birds in a relaxed state.

Prey – an organism that is hunted by predator, food source for predators

Primaries – the largest flight feathers the outer ten flight feathers on the wing, numbered from the wrist outward often described as ‘finger tips’ when observed on a bird in flight

Race – subspecies Although races are distinct within species, they can interbreed. It was previously thought that there were two distinct races of bald eagles, a northern and a southern race, due to the significant size differences between the northern and southern populations. Few sources refer to different races of the bald eagle today. e.g. There are three distinct races of Peregrine Falcon in the US.

Radius – one of the bones in the wing extending from the wrist to the elbow

Raptor – a bird of prey with keen eyesight, a hooked beak and strong talons from the French rapere, to seize and carry off

Remiges – flight feathers located on the wings

Retrices – flight feathers located on the tail

Rouse – when the bird raises all her feathers and shakes, a sign of contentment

Scavenger – an animal that feeds on dead or decaying animal or plant material vultures scavenge animal material, eagles and other predators will sometimes scavenge given the opportunity

Secondaries – flight feathers that attach from the wrist to the elbow

Sea eagles – see Fish eagles

Semi-altricial – an animal or bird that is born or hatched not yet ready to survive independently, but has some fur or downy feathers eagles are semi-altricial

Siblicide – the killing of a sibling eaglets and other young raptors sometimes engage in silicide, particularly when food is scarce

Snake eagles – one of the four major groups of eagles around the world feed primarily on snakes Group includes Short-toed Snake Eagle (Circaetus gallicus), Black-chested Snake Eagle (Circaetus pectoralis) and Brown Snake Eagle (Circaetus cinereus)

Soar – upward flight without flapping often done making use of a thermal, a column of rising warm air Once at the top of a thermal the raptor will often glide to another thermal. Wings are usually fully extended in a soar.

Species – A grouping of birds or animals that can interbreed. A species name is typically denoted with a two word Latin name that identifies both the genus and the species. Bald eagles are Haliaeetus leucocephalus. Golden eagles are Aquila chrysaetos.

Stoop – fast dive by a bird of prey with the wings tucked close to the body, usually in pursuit of prey

Supraorbital ridge – the boney protuberance above the eye socket this ridge helps shade and protect the eye and gives raptors their fierce look

Talon – a sharp, pointed claw on an eagle’s toe each foot has four talons

Tarsometatarsus (pl. Tarsometatarsi) – a bone that is only found in the lower leg of birds and certain dinosaurs the tarsometatarsus is formed from the fusion of several bones found in other types of animals and homologous to the mammalian tarsal (ankle) and metatarsal (foot) bones. The tarsometatarsus of birds is often referred to as just the tarsus or metatarsus.

Telemetry – the science and technology of automatic measurement and transmission of data by radio, satellite or other means from remote sources to receiving stations for recording and analysis

Territory – area around the nest defended by the eagles also breeding territory

Thermal – column of warm air used in soaring

Trailing edge – the back edge of the wing

Transmitter – a device that can be attached to an animal or bird to send global positioning data about the animal’s location used to track movement and migration of wildlife

Tri-colored beak – golden eagles have a distinctly colored beak that is dark at the tip, bluish gray in the middle and light at the base. The tri-color does not include the yellow cere at the base of the beak. The cere is not part of the beak. See Photo

True eagles – one of the four major groups of eagles True or booted eagles have feathers on their entire leg, including on their tarsometatarsi, up to their toes. Golden eagles are part of the true or booted eagle family.

Ulna – bone in the wing extending from the wrist to the elbow the secondary flight feathers attach to the ulna

Vent – opening on a bird through which bodily waste is excreted both solid waste and liquid waste are excreted together and are referred to as mutes also known as the cloaca

Weathering – the practice of allowing captive birds of prey time outdoors

Urgent: Bird hatchling identification - Biology

Birds developed much great mobility than a mammal, but at the cost of being unable to carry its growing offspring about in its body. Unlike, say, a dog carrying a litter of puppies.

The large size of a egg makes it difficult for the female to retain more than a single one egg at a time - carrying eggs would make flying harder and require more energy. (Bird eggs vary in size from the tiny 0.2 gramme eggs of hummingbirds to the enormous 9 kilogram eggs of the extinct elephant bird.)

Just as an aircraft cannot fly if it is overweight, all female birds must dispense with the fertile egg as soon as it is formed. And because the egg is such a protein-rich high-nuitrition prize to all sorts of predators, birds must find a secure place to hatch their eggs. Although birds' eggs appear to be fragile, they are in fact extremely robust. The oval shape applies the same rules of engineering as an arched bridge the convex surface can withstand considerable pressure without breaking. This is essential if the egg is not to crack under the weight of the sitting bird. It takes 26 pounds of pressure to break a swan's egg and 120 pounds to smash the egg of an ostrich.

Finding a place to safely place and hatch their eggs, and raise their young to the point of independence, is a challenge birds have solved in many clever ways. They use artistry, intricate design and complex engineering. The diversity of nest architecture has no equal in the animal kingdom.

In many species the male bird's skill at nest building is a sign of his suitability as a mate he invests huge effort in the task. Males of the European house wren build up to 12 nests to attract females. They will continue to build new nests until a female is happy with the construction.

The edible-nest swiftlets of South-East Asia make a most unusual nest - entirely from their own saliva. The swiftlets build their nests high up on the roofs of a cave. The hard basket-shaped cups are made of concentric rings of a protein-rich goo secreted during the breeding season by the male's enlarged salivary glands. He dribbles long sticky strands, using his beak as a shuttle to weave a cup-shaped bracket onto the cave wall. (Unfortunately for the bird, the nests are a delicacy to some people.)

Birds employ the most astonishing strategies to conceal their young from predators. The female hornbill seals herself into the nest and stays inside the tree cavity throughout incubation, leaving only a tiny aperture. But she was careful to spend a few days testing the male's ability to provide her with food before she committed herself to laying.

Birds will use any available material that they can carry away to build their nest - leaves, sticks, mosses, lichens, feathers. The Australian Yellow-faced honeyeater sometimes filches the thick fur from the back of a koala, a large bear-like mammal, to line its nest.

Ovenbirds are some of the finest nest building craftsmen. They make a variety of nests, ranging from clay domes to stick nests, with intricate tunnel entrances and even underground burrows.

In many species females will carefully peruse the design and quality of the nest the male has build. If she likes it, she will move in if not, the nest may be discarded or destroyed by the male.

The hammerkopf builds what must be the most extraordinary construction in the bird world. The huge, domed nest up to six feet high and across, is made of sticks, reeds and grass and can weigh up to 50 kg. The nest is placed in a tree fork, on a cliff or on the ground. The whole structure may take 6 weeks to build. There is so much room that many other species, such as weaver birds, mynas and pigeons, attach their own nests to this ample frame.

The sociable weaver in Africa constructs the largest and most spectacular of all communal bird nests. The enormous structure with its multiple nest chambers looks like a large haystack in a thorny tree. Up to a 100 pairs may nest in it.

Oilbirds in Venezuela nest in the pitch dark of caves. The ledges behind the mile wide Iguacu Falls on the Brazil-Argentina border are among the most secure nesting places of all. In the permanent damp inches from a constant deluge the great dusky swifts have found the last word in safe houses.

Cuckoos parasitize the nests of a large variety of bird species and carefully mimic the colour and pattern of their own eggs to match that of their hosts. Each female cuckoo specializes on one particular host species. How the cuckoo manages to lay eggs to imitate each host's eggs so accurately is one of nature's main mysteries.

Many bird species learn to recognize a cuckoo egg dumped in their own nest and either throw out the strange egg or desert the nest to start afresh. So the cuckoo constantly tries to improve its mimicry of its hosts' eggs, while the hosts try to find ways of detecting the parasitic egg. One of the most extraordinary examples of deception is practiced by the screaming cowbird. This bird only dumps its eggs in the nests of bay-winged cowbirds. Unlike in any other known brood parasites, the screaming cowbird chicks are absolutely identical to the chicks of the host at the stage when they are dependent on the parents for food, Then, as soon as they fledge, they take on the plumage of their own species.

Another bird that gets away with great deception is the whydah, an African bird with a remarkably long tail. It dump its eggs into the nests of little finches. But the whydah chick does not evict its nest mates instead it grows up with them.

The whydah chick looks completely different from the host nestlings. But when it opens its mouth, the resemblance is remarkable - the young whydah has a gape and mouth spots that closely mimic those of its nest mates. The hard-working parents see no difference in the row of open mouths and feeds them all equally.

The struggle between host and parasite is akin to an arms race, each trying to out-survive the other. But two birds take the struggle up to that old Cold War level MAD - mutually assured destruction. When the gnatcatcher realises the cowbird has laid in its nest, it takes the extreme step of tearing the whole place apart, destroying its and the intruder's eggs in the process. Then it starts all over again.

We hear much about manipulative youngsters in human society. But the young of some birds manage to manipulate their parents even before they leave the egg. The chicks of the American white pelican tell their parents when they are too hot or too cold by giving loud and clear distress calls from inside the eggs. This helps the parents incubate the eggs correctly they respond to the calls by turning and re-settling on the egg.

The greater honeyguide in Kenya is another parasite. It lays its eggs in the nests of the red-throated bee-eater. But its chicks, when they hatch, have a deadly advantage. They are armed with a murderous hook-tipped bill.

The chicks of the red-throated bee-eater die under the vicious attacks of the honeyguide chick within the first few days of hatching. The murder weapon then drops off, its purpose achieved. The foster parents now devote all their energy towards feeding the killer of their own young. The black eagle, which nests on cliff ledges in Africa, is a species whose second chick is always doomed. It always lay 2 eggs. The chicks hatch about 3 days apart, so that the older chick is significantly larger than the younger one.

The eggs hatch over about five days, so at first there is a noticeable size difference between their chicks. You might expect the older ones to win.

But, unlike many other birds, these parrots are scrupulously fair in feeding. They make sure every nestling receives its proper ration. Sometimes the eldest will share its food with the youngest and weakest. The result of this consideration is a truly balanced family. After three weeks strength and weakness will have been ironed out and the nestlings are all the same size.

Perhaps the biggest and happiest of bird families are the Arabian babblers of Israel. These birds display an admirable family togetherness. They all play a part in feeding the baby birds.

Among white-winged choughs four adults are deployed to feed one young, because the beetle grubs they eat is so difficult to find. But they will also kidnap young from another family, enticing them away by spreading their wings like a toreador's cloak. The youngster is fed for the first season, then recruited into the feeding team in the next year. The result is a bigger "family", capable of raising more young.

In British Colombia the Barrows goldeneye also choose the extended family option. The female goldeneye will chase another female off the lake, but is happy to let the rival's abandoned offspring join her family. She may end up with 20 ducklings in tow, only half of them her own. This is not as altruistic as it seems. She does not have to feed them. And if a pike attacks, the odds are 2 to 1 against hers' being eaten.

In Australia, the magpie geese family is often headed by a male and two egg-laying females. When the time comes to conduct their young across a river to the lagoon where they feed, the three parents will snap at marauding crocs, a act of heroism that could easily lose them their heads.

Looked at as a whole, however, birds are not a lot more virtuous or dutiful in their home-making then humans. For example, it has long been thought that birds were the animal kingdom's best representatives of the romantic virtues. The courtship of birds, and their apparent togetherness, has inspired poets, songsmiths and advertising copywriters. We assumed birds don't cheat. Well, they do.

Birds find it pays to deceive their partner as they seek to gain the edge over others of their species, and ensure that their chicks grown to maturity and carry on the lineage.

Although around 90 per cent of bird species form a parental pair, at least for a given breeding season - a higher figure than among other creatures - there is more deception than was ever suspected. Monogamy is not an instinct, hard-wired into animals' brains, as was thought. Even birds considered as paragons of fidelity will indulge in a fling if the situation permits.

The notion of settled married bliss has been blown away by the new technology of DNA fingerprinting, which has revealed that as many as a fifth of the eggs produced by female birds believed to be monogamous had not, after all, been sired by their regular partners.

Staffan Bensch and his colleagues at Lund University in Sweden placed lifelike plasticine eggs in nests kept from previous years. Newly arrived females, thinking the nests belonged to primary females, pecked holes in the plasticine eggs. However they left the incriminating outline of their beak.

The team was able to show that the pecks of jealous female warblers accounted for one-third of all egg attacks, with predators of other species accounting for the rest.

Professor Nick Davies at Cambridge University discovered quite unexpected infidelity in the humble dunnnock, a small, retiring sparrow-like bird found in British gardens, and previously thought to be a model of marital probity.

Davies and his colleagues used DNA fingerprinting to prove that female dunnocks had been unchaste - there was clear DNA evidence that the chicks in a single nest had different fathers.

The female dunnock may be a busy two-timer. However the superb fairy wren of Southern Australia is the most promiscuous bird in the world. Both males and females have multiple partners.

Scientists conclude that what the sexes seem to be doing is widening their options, indulging in extra-marital liasons to increase their chances of breeding successfully.

Researchers are now finding that "divorce" is common, even among birds that were thought to pair for life, like swans. Andre Dhondt of Cornell University studied pairs of Belgian great tits, and found that not only do females often instigate divorce, but they usually benefit from it by subsequently producing more offspring. (Failure to rear offspring is a common cause of avian divorce.)

Lewis Oring of the University of Nevada, Reno, studies the killdeer, a North American plover. He has found "home-wreckers"--individuals that break into the relationship drive out their rival and pair with its mate.

Some males act as a "hired gun" to protect females from predators or males that would kill their young. Steve Emlen at Cornell University contends that female bee-eaters form pair bonds with additional males to reduce the levels of harassment from the many males that hang around their communal nest sites.

In time all birds must leave the nest - provided they have survived the many dangers of home life. There is a great deal of variation in how independent the young are once they hatch from the egg. Among most perching birds, seabirds and birds of prey, the chicks hatch after fairly short periods of incubation and need to be fed for a long time.

In other species, such as geese, swans, ducks and waders, the young develop for a long time within the egg and are fully feathered and ready to run about and feed by themselves almost as soon as they leave the egg. Some can even fly.

The chick that is perhaps the most independent at birth is the ancient murrelet, which is taken to sea almost as soon as it is born. It responds to its parents urgent calls when it can neither fly nor feed on its own.

All About Starlings

Species : European (Common) Starling ( Sturnus vulgaris ) or EUST. There are 11 subspecies in Europe and Asia. The species originally released in the U.S. was probably Sturnus vulgaris vulgaris. NOTE: Starlings are non-native invasive species and are not protected by The Migratory Bird Treaty Act, which means that U.S. federal law allows humane destruction of adults, nests, eggs, and young. You should never allow a starling to use a nestbox, as they will aggressively evict other native birds and may attack their eggs and young.

Interesting facts about starlings

  • Both males and females can mimic human speech. (Some people keep starlings as pets). Some starlings also imitate the song of many other birds like the Eastern Wood-Pewee, Meadowlark, Northern Bobwhite and House Sparrow, along with Blue Jays, Red-Tailed Hawks and Cedar Waxwings. Vocalizations inside the nestbox during nest building can be lengthy and quite varied.
  • An estimated 1/3 to 1/2 of returning females nest in the same box or area in consecutive years. That is why it's even more important not to let them nest in the first place.
  • A starling couple can build a nest in 1-3 days. Both sexes incubate.
  • A migrating flock can number 100,000 birds. They roost communally in flocks that may contain as many as a million birds. Watch this amazing video of a swarming flock of starlings that appear to be feeding.
  • Each year, starlings cause an estimated $800 million in damages to agricultural crops (Pimental et al, 2000)
  • About 15-33% of first broods are parasitized (via egg dumping) by other starlings.
  • Starlings have an unusual bill that springs open to grip prey or pry plants apart.
  • Starlings only molt once a year (after breeding) but the spots that show up in the winter wear off by the spring, making them look glossy black.
  • In Starlings, the length of the intestinal tract actually varies depending on the season. It is shorter in the summertime (when birds are mainly eating protein-rich) insect foods and larger in wintertime when they are mainly eating seeds, which are rich in carboy hydrates. (Source: Analysis of Vertebrate Structure, Hildebrand and Goslow)

Adult starlings are about the size of a chunky Robin. They have glossy black plumage with an irridescent green/purple sheen, a SHORT, squared tail (vs. the long tail of a grackle) and a triangular shape in flight, black eyes (Common Blackbirds have a yellow eye ring), and a long pointy, bill (unlike North American blackbirds) that is yellow during breeding season (January to June) and dark at other times. Legs are pinkish-red. After the first molt, juveniles have grayish brown plumage with lots of white spots (see photo on left) on their head and breast, and they also have a brownish/blackish bill - they almost look like a different kind of bird. It is hard to tell sexes apart. They waddle (vs. hop). Their flight is direct and fast, unlike the rising and falling flight of many blackbirds.

Distribution : After a number of misguided attempts to introduce starlings to North America, perhaps 60-100 starlings were released into Central Park, in New York City, in 1890 and 1891, by an acclimatization society headed by Eugene Schieffelin. Their goal was to introduce all birds mentioned in Shakespeare's works. The entire North American population, now numbering more than 200,000,000, descended from these birds. By the late 1940s (see map), starlings had been seen in nearly all of the U.S. and Canadian provinces. Their population increased from 1966-1976, but seems to have stabilized since, perhaps due to limited nesting sites. They are found as far north as Alaska and the southern half of Canada, down into northern Mexico. BBS Map

Starlings are often found where ever there is food, nest sites and water - typically around cities and towns, and in agricultural areas. The only places they do not frequent are large expanses of woods, arid chaparral and deserts.

They sometimes flock with other birds like grackles, Red-winged blackbirds, and Brown-headed Cowbirds and may feed with rock Doves, House Sparrows and Common Crows.

Migration : Some starlings migrate, others don't. Migration also varies by location - they tend to be least partly migratory in the middle Atlantic states, and mostly migratory in the Midwest and Great Lakes regions. Breeding adults south of 40° latitude generally stay put.

Diet : Starlings are adaptable. They are bold and aggressive scavengers of almost anything, including fruit (especially strawberries, blueberries, grapes, tomatoes, peaches, figs, apples, and cherries ) , grains (e.g., livestock feed), certain seeds, and insects, worms, grubs, millipedes and spiders, and occasionally lizards, frogs and snails. Unlike House Sparrows, 44-97% of their diet is animal matter, depending on the time of year. They are usually seen foraging on open mowed lawns, pastures etc. Starlings seem to have a decent sense of smell - at least they are attracted to peanut butter used in suet.

Nesting Behavior : Starlings are gregarious and will breed in close proximity to other pairs. They are usually monogamous. Fights over breeding sites can result in death. The birds grip each other with their feet while pecking. Nest site fidelity is fairly high, with about one third of returning females coming back to nest in the same box in subsequent years in one study (Kessel, 1957.)

Nestboxes : Starlings can enter a round hole that is 1-5/8" in diameter, or a slot entrance that is 1-5/16" tall (some can enter a 1-1/4" slot). Keith Kridler of TX has found they seem to prefer large (6x6") man-made boxes mounted on metal/telephone poles, or boxes attached to buildings, 8-40 feet off the ground. They will nest in woodpecker cavities and lower heights if other choices are not available.

Most will not enter a crescent shaped hole 2" wide x 1-3/16" tall (often used in Purple Martin houses.) Starlings can not enter a typical bluebird nestbox hole that is 1.5" wide. However, if the hole is enlarged (e.g., by a squirrel or woodpecker) they may gain access. Some people have reported starlings entering the oval hole of a Peterson bluebird box, and the upsidedown mouse hole of a Gilwood box. Even if they can not enter the box, they may be able to reach inside and attack or remove eggs or nestlings.

Starlings fiercely defend their nest site, and are usually successful at evicting many other species of birds, including woodpeckers, Wood Ducks, Tree Swallows, Bluebirds, Purple Martins and Great Crested Flycatchers, Screech Owls and sometimes Kestrels. In Purple Martin houses, they may remove all the eggs or young of a whole colony and build one nest.

Distance between nests : I have not seen definitive data on how close starlings will nest to each other, except for this: "starling's nesting territory includes a 10- to 20-inch radius about the nesting hole. Starlings will nest in close proximity to other starlings and other species, although observations indicate that there is a limit to how close they will tolerate neighbors.&rdquo (Source: Brina Kessel, 1957)

Monitoring : Starlings may be wary of humans, but they are not sensitive to monitoring or disturbance, and any sensitivity declines with repeated exposure.

Nesting Timetable (typical):

  • Nest Site Selection: Like bluebirds, starlings are secondary cavity nesters, meaning they do not excavate their own cavities. (However, they may remove rigid Styrofoam insulation or fiberglass insulation to create a nesting space, and old nesting material. Males select the nest site and then females choose a male/site. Resident males start checking out nest sites in late winter, with migratory males are looking by February or March. Starlings will nest in just about any cavity (including cliffs, burrows, rock crevices) and occasionally even in dense vegetation in trees or on the ground. They prefer holes in buildings (barns and open warehouses, signs, and in soffits and attics of houses) and woodpecker holes or natural cavities in trees. Nest sites are generally 10-25 feet (2-60 feet) off the ground, up to 60 feet. Starlings can easily enter a round entrance hole that is 1-5/8" in diameter. Cavity entrances are, on average, 6.9 x 6.3 cm, 26.4 cm deep, with 149 cm2 of floor area. They will nest in 6" diameter pipe, and in 8" hollow block walls (with a cavity that is about 5"x5".) . They prefer a fairly deep (e.g., 16") nestbox.
  • Nest construction: Males start putting nesting material in the cavity shortly after picking a site. Once they have paired off (late February through March), the couple builds the nest together, usually in the morning and evening. Sometimes the female takes out nesting material brought by the male. They may also remove nesting material (including sawdust or wood chips per Keith Kridler) from a previous nest. A nest can be built in as little as 1-3 days. The nest is bulky and slovenly. The cavity is filled up with grass, weed stems, twigs, corn husks, dried leaves, pine needles, etc, with a depression near the back. Feathers, rootlets, paper, plastics, cloth, string etc. may also be added. The cup lining may include feathers, fine bark, leaves, fine grass etc. Some nests also have fresh green plants (thought to work as fumigants against parasites and pathogens) like yarrow in them. The nest cup is about 7&ndash8 cm in diameter and 5&ndash8 cm deep.
  • Egg laying: Starlings usually lay their eggs in synch with neighbors (the first egg within 3-4 days of other starlings nearby.) Dates range from Mar 15 in the southern part of their range to June 15 in the northern part. Eggs are generally laid between 8:00 and 11:00 a.m. Females lay one egg per day, for an average of 4 to 7 eggs total. The slightly glossy eggs are pale bluish- or greenish-white (rare reports of eggs with fine reddish-brown spots), and are slightly smaller and darker than a Robin's egg.
  • Incubation: lasts about 12 days. It begins with the next or next to last (penultimate) egg. Both sexes develop an incubation patch and brood the eggs, but incubation is mostly by the female (70% during the day and all night long). The female may start to brood right after laying the first egg, increasing the amount of time incubating with each subsequent egg. The parents may cover the eggs with some nesting material when leaving the nest.
  • Hatching: Hatching occurs 11.5 to 12 days after incubation starts. The hatchlings are nearly naked. The gape is bright orange, and the bill is lemon yellow.
  • Development: The nestlings eyes are closed until day 6-7, which is also when contour feathers start to erupt, and brooding ends. Babies can fully thermoregulate by day 13. At this age the babies might try to defecate outside the nest cup or cavity. Before chicks are feathered, adults remove feces. Parents usually remove dead nestlings up to 9 days old. Nests may have tens of thousands of mites in them.
  • Fledging: Chicks fledge in 21&ndash23 days. At least one of the parents may feed the fledglings for a day or two afterwards. The young may hang with adults for up to 10-12 days. One study reported fledglings entering another starlings' nest and stealing food, which resulted in the original brood starving. (Johnson and Cowan 1974)
  • Number of broods: There may be second broods (60% of the time if the first is successful, especially common when the first brood is early), south of 48° latitude. If second broods are attempted, nesting activity begins almost immediately, and laying may start within 6-10 days, or even 1-2 days after fledging, but intervals may be much longer (40-44 days). (Kessel 1957). Nest sites may be used for several seasons in a row. New nesting material is usually put on top of an existing nest. Typically, new material is put over top of any existing nest.
  • Roosts: Winter roosts of starlings are noisy and smelly. Fungal spores from excrement under large roosts can threaten human health and safety due to histoplasmosis, a respiratory ailment.
  • Longevity: A starling in Germany lived to be 21 years and 4 months old (Feare 1984). 33-77% of birds probably die in their first year.

References and More Information :

  • A. C. Bent 1950. Life histories of North American wagtails, shrikes, vireos, and their allies. U.S. Natl. Mus. Bull. 197: 182&ndash214.
  • Cabe, P. R. 1993. European Starling ( Sturnus vulgaris ). In The Birds of North America, No. 48 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences Washington, D.C.: The American Ornithologists&rsquo Union. fact sheet , USDA/APHIS/WS Sample of the starling's song on the Internet Bird Collection - for people who rehab Starlings or keep them as pets which I do not recommend, since they are invasive birds, and wild birds may carry parasites and diseases. (with links to species biology and photos of nests, eggs and young) for other small cavity nesters

It appears that Starlings are capable of seriously reducing martin populations whenever human beings fail to manage colonies, and since most Purple Martins in North America nest in birdhouses, the future may not be hopeful for this species.
- Dr. Charles R. Brown, American Birds, May 1981, Vol. 35(3):266-268.

May all your blues be birds!

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Purple Martins

Like several other bird species the Purple Martin has what is called &ldquodelayed plumage maturation,&rdquo meaning that they take more than one year to acquire their adult plumage. For Purple Martins, it takes two years for both the male and female to acquire their full adult plumage.

During the breeding season there are four distinct age/sex classes for Purple Martins. These are adult male, adult female, subadult male, and subadult female. After nestlings fledge, there is a fifth distinguishable age class of juvenile. Juveniles cannot be sexed by plumage.

The age classes are sometimes described as ASY or After-Second-Year for adults SY or Second-Year for subadults, and HY for Hatching Year for juveniles.

Adult males are the only Purple Martins to have iridescent, purple feathers covering the entire body. They do not get their full plumage until the 3 rd calendar year

Subadult Male

Often the hardest to identify, will have at least one, but usually many solid-purple feathers either on their chins, throats, bellies, or undertails.

Adult Female

Adult females have more purple on their head and back than subadult females. Their undertail feathers are much darker than subadults&mdashall brown/grey feathers with a white rim on the outer edge. They will not have any purplish feathers on their chest, belly, or undertail.

Subadult Female

Subadult females have a much lighter purple to brownish color on their back feathers. The undertails are all white or light-colored feathers with brown pinstripes down the center.

Hatching Year

The sex of a hatching year or juvenile bird cannot be determined by sight. Hatching year Purple Martins will have a stubby tail&mdashshorter than the wing feathers. They are a dull brownish-grey color and still have yellow inside their beak.

Urgent: Bird hatchling identification - Biology

"P recocial" and "altricial," two words describing the degree of development in young birds at hatching, are good examples of useful scientific jargon. They save ornithologists from repeatedly using phrases when single words will do. A precocial bird is "capable of moving around on its own soon after hatching." The word comes from the same Latin root as "precocious." Altricial means "incapable of moving around on its own soon after hatchling." It comes from a Latin root meaning "to nourish" a reference to the need for extensive parental care required before fledging in altricial species. If you consult some of the literature we have cited, you may sometimes see the term "nidifugous" used to describe precocial young that leave the nest immediately, and "nidicolous" to describe young that remain in the nest. All nidifugous birds are precocial, but some nidicolous birds are precocial, too-they remain in the nest even though capable of locomotion. These terms are less widely used than precocial and altricial, and we will not employ them outside of this essay.

Instead of a sharp dividing line between hatchlings that are precocial and those that are altricial, there is a gradient of precociality. In this guide, we recognize the following categories of young:

Precocial Hatched with eyes open, covered with down, and leave the nest within two days. There are four levels of precociality, although only three are found in North American birds. Level 1 of development (precocial 1) is the pattern found in the chicks of megapodes (Australian Malee fowl, Brush Turkeys, etc.), which are totally independent of their parents. The megapode young are incubated in huge piles of decaying vegetation, and upon hatching dig their way out, already well feathered and able to fly. No North American birds show this extreme precociality. Precocial 2 development is found in ducklings and the chicks of shorebirds, which follow their parents but find their own food. The young of game birds, however, trail after their parents and are shown food they are classified as precocial 3. Precocial 4 development is represented by the young of birds such as rails and grebes, which follow their parents and are not just shown food but are actually fed by them.

Semi-precocial Hatched with eyes open, covered with down, and capable of leaving the nest soon after hatching (they can walk and often swim), but stay at the nest and are fed by parents. Basically precocial but nidicolus, this developmental pattern is found in the young of gulls and terns.

Semi-altricial Covered with down, incapable of departing from the nest, and fed by the parents. In species classified as semi-altricial 1, such as hawks and herons, chicks hatch with their eyes open. Owls, in the category semi-altricial 2, hatch with the eyes closed. If all young were divided into only two categories, altricial and precocial, these all would be considered altricial

Altricial Hatched with eyes closed, with little or no down, incapable of departing from the nest, and fed by the parents. All passerines are altricial.

Note that in the species treatments in this book we use the term "fledging" (F:) for the number of days it takes for the young of an altricial or semi-altricial bird to acquire its full set of feathers, after which it leaves the nest. Thus for altricial and semi-altricial birds, the time needed to get fully feathered and time spent in the nest are essentially the same. In precocial and semi-precocial birds, F: indicates not the number of days that pass before the young leave the nest, but the time from hatching until they can fly.

Left: House Sparrow hatchling (altricial-naked, blind and helpless on hatching).
Right: Ruffed Grouse hatchling (precocial 3-downy, open-eyed, mobile on hatching, follows parents and is shown food).

Characteristics Of Nestlings
(modified from O'Connor, 1984)

ABSENT? EXAMPLES Precocial 1 Yes Yes Yes Yes Yes Megapodes Precocial 2 Yes Yes Yes Yes* No Ducks, Plovers Precocial 3 Yes Yes Yes Yes No Quail, Turkey Precocial 4 Yes Yes Yes Yes/No No Grebes, Rails Semi-precocial Yes Yes Yes/No No No Gulls, Terns Semi-altricial 1 Yes Yes No No No Herons, Hawks Semi-altricial 2 Yes No No No No Owls Altricial No No No No No Passerines . t = Precocial 3 are shown food.
. *= Precocial 2 follow parents but find own food.
Why have these different modes of development evolved? They are obviously tied into two important aspects of the bird's environment: food availability and predation pressure. Precociality puts a premium on the ability of females to obtain abundant resources before laying. They must produce energy-rich eggs to support the greater in-egg development of the chicks (eggs of precocial birds may contain almost twice the calories per unit weight as those of altricial birds). Females of altricial species do not have such large nutritional demands before egg laying, but must be able (with their mates) to find sufficient food to rush their helpless young through to fledging. While the young are in the nest, the entire brood is extremely vulnerable to predation and is dependent on concealment of the nest and parental defense for survival. In contrast, precocial young, having left the nest, have some ability to avoid predation, and there is a much smaller chance of the entire brood (as opposed to single chicks) being devoured.

Interestingly, there seems to be an evolutionary trade-off in bird brain sizes related to the degree of precocity. Precocial species have relatively large brains at hatching-as one might expect since the young, to one degree or another, must be able to fend for themselves. But precocial species trade for this advantage an adult brain that is small in relation to their body size. Altricial young, in contrast, are born small-brained, but on the pro-tern-rich diet provided by the adults (and with their highly efficient digestive tracts) postnatal brain growth is great, and the adults have proportionally larger brains than precocial species.

Parrots have evolved their way into the best of both worlds. They are altricial, but the female invests in a nutrient-rich egg just like females of precocial species. Parrots are among the most intelligent of birds they have adopted the same evolutionary strategy as we have. People (like other primates, elephants, and antelopes, but unlike rodents and marsupials) are precocial-born with hair, open eyes, and large brains. But our brains and those of parrots, both large at birth, also grow a great deal after birth as a result of large parental investments of food energy.

Thus a complex evolutionary problem of balancing the need to provide nourishment to the young and to protect them from predation has been

"solved" by each group of birds-and the solutions are the different avian developmental patterns we now observe. Similar problems have been solved, also in diverse ways, in the course of mammalian evolution. But many more groups of mammals than birds have managed to become big-brained as both young and adults.

Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.

These Birds Learn Their Mother's Calls Before They Hatch

A recently-published study reveals that nestlings of Australia's Red-backed Fairy-wrens learn their mother's calls before they hatch. These calls are a "vocal password" that the parents rely upon to identify their chicks. Thus, parent birds invest more effort into raising nestlings whose calls are most similar to their own.

Female Red-backed Fairy-wren (Malurus melanocephalus), Samsonvale, SE Queensland, Australia. . [+] (Credit: Aviceda/CC BY-SA 3.0.)

Fairy-wrens Are Very Good Listeners

A few years ago, scientists discovered that female superb fairy-wrens, Malurus cyaneus, teach their chicks a special "vocal password" before they even hatch (ref & ref). This strategy is just one of several that apparently evolved during the so-called "arms race" between fairy-wrens and their brood parasites. Teaching their chicks a special vocal password allows fairy-wren parents and their nest helpers to identify and to preferentially feed their own chicks whilst mostly ignoring chicks of other species that are snuck in their nests.

The sneaky species, Horsfield's bronze-cuckoo, Chrysococcyx (Chalcites) basalis, and brush cuckoos, Cacomantis variolosus, are brood parasites that lay an egg or two into the fairy-wrens' nests, in the hope that their chicks will deceive the fairy-wren parents into preferentially feeding and caring for them. Since even newly-hatched superb fairy-wren chicks can produce their mother's vocal password, whilst cuckoo chicks cannot, experienced fairy-wren parents are not fooled by these interlopers.

Adult Horsfield's bronze-cuckoo (Chrysococcyx basalis), Capertee Valley, NSW, Australia. (Credit: . [+] Aviceda/CC BY-SA 3.0.)

But superb fairy-wrens aren't the only fairy-wren species that are parasitised by cuckoos. Knowing this, the lead author of the original studies, behavioral ecologist Diane Colombelli-Négrel, now a fully-fledged postdoctoral researcher at Flinders University in Australia, wondered whether this particular behavioral strategy is unique to superb fairy-wrens, or if other fairy-wren species also teach their offspring a special vocal password whilst their chicks are still embryos?

"After we discovered embryonic learning in superb fairy-wrens, we started to question how widespread this phenomena was", said Dr Colombelli-Négrel in email.

"The red-backed fairy-wrens, being close relatives of the superb fairy-wrens, were the ideal choice to start answering this question", said Dr Colombelli-Négrel.

Female Red-backed Fairy-wrens Sing to Their Eggs

Dr Colombelli-Négrel's initial discovery that female superb fairy-wrens sing, or call, to their eggs was a very lucky accident (ref).

“Because fairywrens have high predation rates, we originally placed microphones under Superb Fairywren nests to record alarm calls against predators, twenty-four seven”, said Dr Colombelli-Négrel about her previous research.

“As a result, we discovered embryonic learning in Superb Fairywrens.”

Brisbane field site where one of the study populations of red-backed fairy-wrens live. (Credit: . [+] Diane Colombelli-Negrel/The Auk.)

To establish whether female red-backed fairy-wrens, Malurus melanocephalus, also teach their chicks a vocal password, Dr Colombelli-Négrel and her team replicated their earlier superb fairy-wrens study. They placed microphones under red-backed fairy-wren nests and recorded all vocalisations for two continuous hours each morning between days 10 and 14 of incubation. They also recorded nestling begging calls at 36 of the 67 nests for two continuous hours per nest between days 3 and 7 of the nestling phase. Eleven of those 36 nests were also recorded daily from hatching.

Spectrogram analysis of the red-backed fairy-wrens' vocalisations revealed that two types of song elements (elements A and B in Figure 1) are contained in female red-backed fairy-wrens' nest calls. Further, the analysis found that one of those song elements, element B (which is also referred to as the "signature element"), was faithfully replicated by newly hatched nestlings (Figure 1):

FIGURE 1. Spectrograms from four nests (two from the Brisbane site and two from the Cairns sites) . [+] showing some examples of the two element types described in this study: element A and element B element B is also known as the signature element. (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

After the team established that female fairy-wrens sang whilst incubating their eggs, and that their nestlings dependably produced the signature element in their mother's nest song, they then wanted to know if the chicks were learning their mother's special signature element whilst still embryos? This meant they also had to determine whether, or if, the females sang to their chicks after they hatched. To answer these questions, the researchers monitored all nests (67 in total) and found that 62% of the females continued to call after hatching, stopping only five or six days after hatching (Figure 2):

FIGURE 2. Percentage of nests at which incubation and post-hatching calls were detected after the . [+] onset of hatching: data are presented separately for Brisbane (in grey) and Cairns (in black). (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

"The one thing that surprised me with the red-backed fairy-wrens is the fact that female red-backed fairy-wrens, unlike superb fairy-wrens, had a different temporal pattern for their calling behaviour: they started at day 5 of incubation and continued until 5 days after hatching”, said Dr Colombelli-Négrel in email. She noted that this behavior contrasted with superb fairy-wrens, who only called during the last few days of incubation, and stopped after the chicks hatched.

Nestlings Imitate Song Elements in Their Mother’s Calls

To determine whether the chicks were specifically imitating their mother's calls instead of those produced by, say, another female nesting nearby, Dr Colombelli-Négrel and her team recorded a total of 619 incubation and post-hatching calls from 27 females at the Brisbane site and 1,040 incubation and post-hatching calls from 40 females at the Cairns sites. They also recorded the female and her nestlings at 10 nests (267 begging events recorded in total) at the Brisbane site and at 26 nests (968 begging events) at the Cairns sites.

Spectrogram analysis of the nestlings' begging calls revealed they were significantly different between nests. Additionally, spectrogram analysis also showed that each female's signature element was significantly different from other signature elements produced by any other female (Figure 3):

FIGURE 3. Average SPCC values (mean ± SE) for (1) within vs. between female element B comparison, . [+] (2) within vs. between chick calls comparison, and (3) females vs. their own and other young element B comparison. The data are presented for (a) Brisbane (n = 27) and (b) Cairns (n = 40). (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

Not only were the nestlings' begging calls most similar to the incubation calls produced by their mother, and this similarity was strongly related to the number of incubation and post-hatching calls produced per hour during incubation, yet this similarity was not related to the calls produced by the chicks' mother later, during the nestling period (Figure 4):

FIGURE 4. A positive correlation between incubation call rate and call similarity (regression . [+] weighted by site: β = 0.34, p = 0.05, n = 33). (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

Chicks Whose Begging Calls Were Most Similar To Their Mother's Calls Received More Food

To test the importance of the nestlings' begging call similarity to that of the mother's signature element, Dr Colombelli-Négrel and her team conducted playback experiments where they broadcast nestling begging calls that they had recorded at five other nests on their study sites. These broadcasted recordings featured the begging calls made by hungry nestlings that were the same age as those in the study nest.

The team found that red-backed fairy-wren parents were more likely to feed nestlings associated with broadcasted recordings that sounded most like the mother's own song element B (Figure 5):

FIGURE 5. Percentage of nest visits that resulted in food delivery to nestlings (% successful feeds) . [+] in relation to call element similarity between the attending female’s element B and the experimental nestling begging calls: we found that nestlings were fed significantly more when nestling element similarity was higher. (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

Female Fairy-wren Call Rate Was Not Affected By Cuckoo Abundance

But why did the fairy-wren chicks have to produce begging calls that were very similar to their mother's signature element? Dr Colombelli-Négrel's original work indicated that it was important for the parent birds to distinguish their nestlings from those of brood parasitic cuckoos. So Dr Colombelli-Négrel and her colleagues tested that hypothesis, and were surprised to find that the rate at which red-backed fairy-wren mothers called to their eggs did not increase significantly when more cuckoos were present in the habitat (Figure 6):

FIGURE 6. Nestling begging call element similarity in relation to cuckoo prevalence, defined as . [+] either lower (number of nests with evidence of parasitism ,1.5%) or higher (number of nests with evidence of parasitism .3%). We found that element similarity between mother and young was higher when parasitism prevalence was higher (F1, 35 1⁄4 4.82, p 1⁄4 0.03) at the Brisbane site, but not at the Cairns sites. Bars depict mean +/- SE. (Credit: Diane Colombelli-Négrel et al. doi:10.1642/AUK-15-162.1)

This was not what they expected. Which raises the question: what is the evolutionary reason for the parents' bias towards nestlings that best replicate their mother's calls? In the light of these new findings, Dr Colombelli-Négrel and her colleagues speculate that the similarity of nestlings’ calls to the mother's calls may indicate which nestlings are the healthiest and the best learners, so the parents can then invest more resources into those that are most likely to thrive -- distinguishing their own chicks from cuckoo chicks might be an added bonus.

Cuckoo hatchling in a red-backed fairy-wren nest. (Credit: Diane Colombelli-Negrel/The Auk.)

Vocal Learning Occurs Earlier In Birds Than We Ever Knew

“One of the main takeaway messages from this study is that 'through the egg' learning may be a common phenomenon in birds, and something worthy of more research attention,” said William Feeney, a Postdoctoral Research Fellow in the School of Biological Sciences at the University of Queensland.

“So far, it has only been demonstrated in two closely related Australian fairy-wren species, so similar studies in different genera is required to determine how wide spread this phenomenon is, as well as its purpose,” said Dr Feeney in email.

Dr Feeney, who is an expert on the interactions between cuckoos and their host birds, then pointed out: “The authors suggest that it may be related to identifying brood parasitic chicks (ie. cuckoos) so that they can accordingly discriminate against them by abandoning the parasitised nest (cuckoos evict the host's own chicks, making brood parasitism particularly costly to the host). This is an interesting idea that requires further investigation. While this current study did not produce significant results in its support, this may be expected as red-backed fairy-wrens experience lower levels of parasitism compared to the superb fairy-wren. It would be interesting to conduct further research to see if non-host species also exhibit through the egg learning,” said Dr Feeney.

Might the mother's nest calls endanger her eggs and nest?

"In contrast to previous work on the superb fairy-wren, they found no evidence that the mother's 'incubation' call rate affected rates of nest predation,” said Dr Feeney.

"This may simply be because red-backed fairy-wrens generally experience lower levels of nest predation compared to superb fairy-wrens, making it harder to detect an effect (I have noticed that red-backed fairy-wrens are much more secretive than superbs in the field),” said Dr Feeney. "It may also suggest that there are other reasons that may underpin this ability (such as indicating "good learners" to parents).”

This study indicates that early vocal learning may be more commonplace amongst songbirds than thought.

"[T]his study is important as it provides evidence for a second species that has this ability and raises questions regarding why it may have evolved in the first place,” said Dr Feeney.

“Fairywrens have become a new model system in which to test new dimensions in the ontogeny of parent-offspring communication in vertebrates,” agreed the study's co-author, animal behaviorist Mark Hauber, a professor of comparative psychology at Hunter College.

This research makes me wonder whether early vocal learning is typical for all fairy-wren [Maluridae] species? Dr Colombelli-Négrel and her collaborators are already working on answering this question collecting more data on superb, red-backed, splendid, variegated, and red-winged fairy-wrens.

"We also would like to extend our work to species other than Maluridae to investigate if females in general call to their eggs and their potential benefits", said Dr Colombelli-Négrel.

Adult male Red-backed Fairy-wren (Malurus melanocephalus). (Credit: J Welkin/The Auk.)

Diane Colombelli-Négrel, Michael S. Webster, Jenelle L. Dowling, Mark E. Hauber, and Sonia Kleindorfer (2016). Vocal imitation of mother’s calls by begging Red-backed Fairywren nestlings increases parental provisioning, The Auk: Ornithological Advances 133 273–285 | doi:10.1642/AUK-15-162.1

Colombelli-Négrel D., Hauber M., Robertson J., Sulloway F., Hoi H., Griggio M. & Kleindorfer S. (2012). Embryonic Learning of Vocal Passwords in Superb Fairy-Wrens Reveals Intruder Cuckoo Nestlings, Current Biology, 22(22):2155–2160 | doi:10.1016/j.cub.2012.09.025

Diane Colombelli-Négrel, Mark E. Hauber, Sonia Kleindorfer (2014). Prenatal learning in an Australian songbird: habituation and individual discrimination in superb fairy-wren embryos, Proceedings of the Royal Society of London B, 281(1797):20141154 | doi:10.1098/rspb.2014.1154

W. E. Feeney, I. Medina, M. Somveille, R. Heinsohn, M. L. Hall, R. A. Mulder, J. A. Stein, R. M. Kilner, and N. E. Langmore (2013). Brood Parasitism and the Evolution of Cooperative Breeding in Birds, Science, 342(6165):1506-1508 | doi:10.1126/science.1240039 [$]

Read more about red-backed fairy-wrens: Birds Sing Duets To Reduce Cheating

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Although I look like a parrot in my profile picture, I'm an evolutionary ecologist and ornithologist as well as a science writer and journalist.


This work was supported by several European Union projects: CGL-2004-0161 BOS, cofinanced by the Spanish Ministry of Science and Education and the French institutions the Fondation pour la Recherche sur la Biodiversité (under its DREAMS project), the French National Research Agency (under its ALIENS project), and the Ministère du Développement Durable (under its Ecotropic program) EB was supported by a Conseil Régional de Provence—Alpes—Côte d'Azur PhD fellowship. Five anonymous referees gave useful comments and suggestions that greatly helped improve the manuscript.

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