|
Abandonment
Phainopepla by Doris Evans
 |
“I found a baby bird. It was abandoned by its parents.” This is one of the more common fallacies we hear expressed, especially during the nesting season. I explain why that particular baby, and almost all such babies, are never abandoned by its parents. Unless both parents are killed or severely injured, parent birds never intentionally abandon their offspring. Humans, and some mammals, will abandon their babies for a variety of reasons but birds, which greatly outnumber humans on the planet, almost never do.
In my research, I have never come across any documentation that sites a single example of abandonment. Of course, like anything else, there may be exceptions. Some species will destroy eggs or hatchlings of parasitic nesting birds, like cowbirds. But the overwhelming majority of birds facing a similar problem never recognize the difference between cowbird (or other parasitic nesting species) eggs or newborns and will continue to nurture them even if their own natural babies perish in the process. Some researchers suspect that in rare, although never documented, cases some parent birds may dispose of grossly deformed or otherwise ill-fated babies. In some cases, especially species with larger broods, the first hatched babies are invariably larger and more well-developed than the last to hatch. In some such cases, the larger nestmates may outcompete the smaller, less-developed babies with the result that the last born may suffer from malnutrition and not survive to a become fledgling. However, this is not due to the parent birds trying to ensure the survival of all their offspring.
Precocial/Altricial Chicks
Babies must learn quickly how to survive. Precocial and altricial chicks differ in their earliest upbringings. Precocial birds hatch from their eggs with eyes open; have a soft, downy feather covering that enables them to thermo-regulate individually; can walk and run immediately after hatching; and their brains, muscles, and limbs account for a greater proportion of their weight than do those of altricial nestlings. Precocial birds immediately imprint and bond with the parent birds. An easy example of how this works, and one that many of us have observed, is that of the quail family. Babies hatch out of their eggs and immediately follow their parents, who begin teaching them how to survive: how and where to find food, water, and shelter; how to communicate with the rest of the family by learning their calls; how to avoid predators; and other skills that will remain with them for the rest of their lives and, in turn, can be taught to their own offspring when the time comes. All this learning begins immediately after hatching. In short, Precocial birds are born with the innate, inherent ability to survive and learn all the skills they need to successfully grow into adults and become parents themselves. Gallinaceous birds, ground-dwelling and ground-feeding birds (fowl-like birds such as quail, turkeys, ducks and geese, domestic chickens, etc.) are primes examples of precocial species. Other examples of precocial birds include Ostrich; pheasants; kiwis; and most shorebirds.
Gambel's Quail by Richard at SearchNet Media
|
|
Altricial Chicks
Altricial chicks are helpless at birth. They are born with closed eyes (eyes usually open within days or the first week or so after hatching, depending upon species), naked and featherless, cannot fly and are unable to leave the nest for anywhere from a week to months, are fed directly by the parents, and are wholly dependent upon their parents for all their needs. Many parents of altricial birds will even carry baby excrement away from the nest, keeping it sanitary and parasite-free as much as possible. Chicks are also dependent on their parents for protection and security from predators and extremes in weather conditions (fierce storms, excessive heat or cold, drought, and other extreme/unusual conditions). Altricial birds usually raise their babies in nests, such as cupped nests or cavities, located in elevated positions above ground level. All passerines (perching birds, as opposed to ground-dwelling and ground-feeding gallinaceous birds) are included in this category. Prime examples of altricial birds include the families of woodpeckers, hummingbirds, swifts, trogons, kingfishers, doves and pigeons, parrots, etc. While it is instinctual for these types of babies to know how to lift their beaks straight up for parental feeding, most of their basic learning begins when they reach fledgling stage.
Other Classifications of Chicks
The vast, overwhelming number of species will fit the description of either precocial or altricial birds. However, for a very small minority of species, their classification is slightly outside the well-known parameters of those two types, but they are closely related, with only minor differences. Semialtricials are able to leave the nest within hours of birth or within a day or two after hatching. However, they remain on or near the nest where they are fed and brooded by their parents. Examples of semialtricial species include gulls, terns, skimmers, goatsuckers, albatrosses, etc. Subprecocials are able to leave the nest as soon as they hatch, or at most within a day or two, follow their foraging parents and are fed directly from their bills. Examples of this classification include grebes, rails, cranes, guans, some pheasants, etc. And the rarest of birds fitting the last classification, superprecocials, are limited to the megapodes and the Black-headed Duck. Megapodes are large-footed gallinaceous birds that build mounds to lay their eggs in and let the heat of the earth, sun, and the fermentation of decaying vegetation within the structure of the mound incubate the eggs. The superprecocial newborns are wholly independent of parents from the moment they hatch, or at least as soon as they are dry from the liquid in the interior of the egg.
Curved-billed thrasher by Richard at Searchnet Media
 |
Incubation Behavior
Between the laying and the hatching of the eggs, the parents’ prime concern is their incubation. Some species incubate the eggs together, rotating, either by the hour or by day/night shifts. In some species, only females incubate the eggs. In other species, males will perform all the incubation and parenting responsibilities if the females are taken by predators or experience some other cause of death. During the incubation period, which varies by species, the parent bird’s main responsibility is keeping the eggs at a stable warm temperature. Additionally, they must find food for themselves and insure a food supply for their soon-to-be-hatched babies. Protecting the eggs from predators and other possible enemies keeps the parents alert to danger. These duties are unhesitantly performed by the adults and after the eggs hatch, birds enter the most strenuous phase of their breeding activities. Hardly any other animals work so hard for their young, or attend to them in so many ways, or make such obvious sacrifices for them, as birds do.
Methods of Feeding
Most mammal parents feed themselves, and then provide mother’s milk to nourish the babies through the earliest stages of development. Some exceptions, such as carnivores like foxes and coyotes, bring food for their older offspring to eat. And, aside from birds, the other major examples of parents feeding babies mouth-to-mouth are the social insects, including bees, wasps, ants, and termites. Like many nesting bird species, many of these insect species also attend to the sanitation of the cells that contain their larvae. Most of these social insects will swarm to attack enemies to protect their offspring.
Parents Protecting Nesting Territory
I suspect many readers have encountered situations where birds will swoop down to drive off potential predators if they get too close to the nest. Mockingbirds, thrashers, and some owls and raptors have dive-bombed even humans in attempts to discourage and divert potential predators or territorial intruders. I’ve had a barn owl attack me and leave a bloody scratch on my head. Another time a mated pair of Cooper’s Hawks attacked my head from behind. The first hawk swooped in on me from the rear and its talons shifted my hat forward and its mate, following close behind, actually grabbed my hat in its talons and carried it about 100 feet before dropping it. In both cases, I was unaware I had ventured too close to their nests. These examples demonstrate how dedicated the parents are in defending their nesting territory. Many folks have inquired about their personal observances of parent mockingbirds defending their nesting territories. Aside from other avian species, mockingbirds will defend against cats, dogs, and even humans. Thrashers demonstrate similar behavior.
Altricial Nestlings
Altricial nestlings are basically helpless and dependent on their parents to ensure their survival. They are far less attractive than the downy, bright-eyed, and more advanced precocial chicks, often resembling prematurely hatched embryos. This is particularly true for some species our readers may be familiar with. The grub-like newly hatched hummingbird chicks and underdeveloped hatchlings of the woodpecker family may best exemplify this. Their eyes are tightly closed, their swollen abdomens grotesquely disproportionate to the rest of their bodies, and their skin often imperfectly covered in down feathers or nakedly bare-skinned altogether.
Coloration Assists Parents Feeding Nestlings
Nature itself helps teach parent birds, especially first year breeders, locate the perfect place to deposit food into the hungry babies’ mouths. We’ve all seen, either in real life or in photos, babies in the nest with their heads pointed up and their beaks open wide, waiting or expecting to be fed. The widely gaping mouth reveals its brightly colored interior, the color of which is fairly uniform throughout a family: red in finches, tanagers, and others; yellow or orange in vireos, thrushes, wrens, nuthatches, swallows, flycatchers, and others; in warblers, the lining of the mouth may be either yellow, red, or yellow with red or pink in the center. Blue-gray Gnatcatchers and members of the cuckoo family have yellow mouths with two conspicuous black spots on the tongue. These intense colorations aid the parent birds in guiding them to the direct spot where they need to deposit the food. With multiple birds clamoring and competing in a small nest, and quite possibly, the foodstuffs they are carrying in their bills (such as large insects) partly obscuring their vision, the parent birds rely on this specialized coloring of the interior of the mouth to ensure the babies get fed.
Gambel's Quail by Richard @ SearchNet Media
|
|
And, if the nestling’s gaping mouth were not conspicuous enough, its apparent size is visually increased by the presence of flanges, or projecting folds of skin, at the corners of the mouth. These flanges act like framing devices, helping to guide the parent bird’s bill into the center of the nestling’s mouth. These are usually orange, yellow, or white marking a stark contrast with the coloration of the mouth’s interior. These colorations are remarkably efficient in gathering and reflecting light. So even under poor light conditions (on pre-dawn, post-dusk, or overclouded days), parent birds can effectively feed their offspring. Early ornithologists thought that babies’ mouths were actually luminescent organs, but when later researchers placed the birds in total darkness, this theory was quickly disproven.
Another theory regarding the parent birds using the colorations to guide them in delivering foods, still considered valid today, is that the colorations increase the desire of parents to feed the babies. When a nestful of drowsy nestlings suddenly stretch their necks upward at the parents’ approach with a bill full of food, the visual effect is beautiful. It is likely that, as a result of the birds’ excellent eyesight and their sensitivity and attraction to color, the nestlings’ colorful mouths and flanges encourage and increase the parents’ desire to continue feeding. Cavity-nesting passerines tend to have even more conspicuous oral flanges than open nesters, due to the decreased light inside the bottom of the cavity. Some species are the exception to the rule. Baby rails, coots, and grebes rely on colorful heads and external bills to guide parents in delivering food. Other species may have colorful crown stripes or V-marks on their foreheads to serve a similar function. In short, just as birders rely on colorations and field marks to identify species, parent birds rely on coloration and field marks delivering food to those ever-hungry babies. As nestlings and fledglings, most species lack colorful exterior patterns or prominent field marks which helps them remain unseen by predators and enemies. As juveniles and sub-adults, they will soon be refashioning themselves with their adult plumage.
Maturing Chicks
Leaving the nest often marks the beginning of the young bird’s real-life education. Most species are still dependent on their parents for most of their learning how to live in the world. Leaving the nest marks a victory for the parent birds who have successfully nurtured their offspring until they are ready to learn the essential lessons of survival. Reaching the fledgling stage of development demonstrates the parents’ success in the raising and protecting their offspring. The parent birds have probably brought their young through many challenging perils, which may claimed other nestlings and young fledglings. But to reach maturity the young must still escape many other dangers, but they are no longer at risk of being lost together while they lay in a helpless cluster in the nest.
Continued Parenting Out of the Nest
 Gambel's Quail by Richard at SearchNet Media
|
The young bird’s passage from the nest into the larger world happens as abruptly as its earlier escape from the eggshell. Now it has to navigate a perilous world where dangers lurk just out of sight, where it must learn where and how to forage, avoid enemies and predators, and find a safe place to rest and preen during the day and roost during the evening. Fortunately for most young birds, the transition from the sheltered life of the nest to the far more difficult life in the larger world is softened by the continuing care of their parents. The parent birds will continue feeding the chicks and assisting them in learning how to find food for themselves. The parents will continue to provide as much protection as they can and begin teaching the chicks how to protect themselves, “educating” them in all the important survival strategies they need to mature, breed, and provide for the continuation of the species. Only a few species (especially the megapodes, certain swifts, and a number of seafowl) leave the nest without a parent to guide and protect them.
Inherent or Learned Knowledge?
When I use the term “educate,” which may or may not be the best word but which is easily understood, I am referring to the gathering together of all the skills and knowledge necessary for a young bird to be able to not only survive and take care of itself, but to thrive. Some of this knowledge is inherent; they are born with instincts adequate for their needs. The other type of knowledge is not instinctual but learned from their parents or acquired from observation, experimentation, and practice. Sometimes, in some circumstances, it’s a fine line that distinguishes inherent knowledge from learned behavior. When fledglings are feathered enough and mature enough to recognize the need to finally fledge the nest, they will spend a few days exercising their flight muscles preparing for their first flight. Next, they will stand on the rim of the nest and flap furiously till they begin to lift off the nest a short distance and quickly drop back down onto the nest. This will be repeated until they have enough confidence to go outward away from the nest instead of up and slightly off the nest. The last step is actually flying. The young pre-flight birds have observed the comings and goings of the parent birds and possibly the older members of the brood in their pre-flight behavior. This is probably more learned than instinctual. But, the actual act of flying demonstrates instinctual behavior. They must be successful on the first attempt for there may not be a second chance.
Learning Necessary Skills Early
 Mallards by Doris Evans
|
Parent birds are instrumental in the education of their young. It is from their parents that they learn where and how to find food, what to avoid, and, every bit as important, the songs and calls of their species. Being able to communicate with parents, siblings, and others will help keep them safe and learning all the lessons they must master. Calls keep the family, and/or flock, together. Calls will reunite young birds that get separated, alert them to danger, and inform them to “freeze” in place or be silent until danger passes. Calls can lead the young to food. Songs, inherent in some birds and learned by others (to varying degrees), enable birds to attract mates and some researchers claim songs can be manifestations of their emotional feelings.
Imprinting of Chicks
Usually, the first thing fledglings accomplish is imprinting. Imprinting is the process of bonding between parent birds and their young. Researchers understand that, to some degree, imprinting is inherent knowledge—the birds are born with it. Some researchers claim that while the imprinting may be inherent, the birds must learn who to bond to. This is easily understood and often visible to those who observe birds. An easy example are the quail. As precocial babies, they hatch out from their eggs and as soon as the last-hatched egg becomes a chick, the parent birds will walk off while calling instructions to the rest of the family. The parent birds are the first birds the newborns see and recognize as parents. They follow the parents. They almost immediately imprint with the parents. Captive-bred species, such as California Condors, are bred under laboratory-like conditions, yet the researchers take careful measures to hide their human identities for fear the chicks will imprint on them and consider them their parents. For precisely this reason, those researchers charged with overseeing the seeing and care of condor chicks use condor hand puppets to feed the babies, allowing the babies to imprint on the condor rather than human features.
How Chicks Imprint
It is thought by most researchers that some species will imprint, or bond, with the first object they see. If it is a human, there’s a good likelihood that the human will become the surrogate parent via imprinting. This bonding process has been more studied with domestically raised ducks, goslings, and chickens. Researchers have realized that in some cases it will be the mother or an unrelated hen that hatched the young. But researchers have found chicks will imprint on a wide variety of subjects, such as a different species of bird, a wooden model of the same species, humans of either sex or any age, a football, a box containing a ticking alarm clock that is pulled slowly along by a rope, or even a slowly moving shadow low on a nearby wall. The object by which the hatchling becomes imprinted must show at least one of the characteristics of a living animal: it must either move or emit a short, low, repetitious note or call. If it does both, the imprinting will be happen faster and be quite effective. The object the hatchlings imprint to must have some sign of animation to avoid the hatchling’s imprinting to a rock or a plant, neither of which can provide guidance or protection to the young bird. Most young birds imprint within minutes or hours; a few species may take up to 24 hours or so. An improperly imprinted bird faces a world of uncertainty and, likely, a shortened life.
Learning to Eat
 Finch by Richard at SearchNet Media
|
Learning to eat is inherent knowledge, but knowing where to find the correct food is learned behavior. They don’t have to learn to open their mouths, for example. However, in some species, parents are helpful with instructions. Fish-eating birds usually are taught by their parents to swallow fish whole and head first. In this manner the meal will glide down their gullet. If they tried to swallow tail first, they wouldn’t be able to feed and could actually harm themselves. So, for some species, parents will guide them on how to correctly pick up and even swallow certain foods.
Parent birds need to teach their babies how to forage effectively in a natural environment and not waste time and energy. They teach by example, reinforced with vocal calls. Chicks have to learn what foods constitute their natural diet. They need to learn from the immense variety of swallowable objects which are foods and which foods are wholesome and nutritious and how to avoid those that are harmful, dangerous, or poisonous. This is behavior learned from parents that is only gradually perfected. Young birds must learn to avoid inedible or dangerous objects and plants.
What Chicks Eat
The various types of foods birds eat will determine how the parents teach the young to forage for themselves. Insectivores learn differently than seed eaters. Fruit-eaters have specific skills to master. As do fish-eaters. Raptors feed still differently. Even seed-eaters have their preferences and have to learn which are the best seeds to eat and which to avoid. Birds that have severely restricted ranges usually depend on a single source of food or a minimal number of foodstuffs. Lesser goldfinches have restricted ranges and, at least in backyards, eat only one food provided for them, Nyjer thistle, while avoiding all other seed types. Northern Cardinals, with much more widespread ranges, eat a variety of foods. While they prefer many seeds and nuts, they will eat fruits, insects, and tender young plant shoots or sprouts. Parent birds have to teach their young about the foods they eat.
Phainopepla by Doris Evans
|
Learning What Not to Eat—Insectivores
Insectivore chicks must learn to distinguish the insects that provide nourishment and are good to eat. Learning which insects to avoid is often a displeasing experience. While in the nest, chicks learn that the types of insects their parents feed them are good foods. But once they are fledged and begin to experiment with other insects, their own experiences teach them what to avoid. They quickly learn that many brightly-colored insects are warning potential predators that their bright colors mean that not only are they distasteful to the point of disgusting, but that they contain chemical substances that cause physical pain, distress, or alarm or fright. Some insects are actually poisonous. Young birds do not instinctively recognize this danger; this is an example of learned behavior. Researchers have discovered that such first experiences with distasteful, colorful insects such as butterflies and wasps are remembered by those chicks for as long as 14 months. Fledglings are often overseen by their parents in learning to forage for insects. If the chick attempts to eat dangerous or foul-tasting insects in the presence of the parent birds, the parents will voice alarm calls or distress displays. When other chicks from the brood see how the parents warn that chick not to eat a particular insect, or observe the negative result of an attempt, they learn from observation not to make the same mistake. This is another example of learned behavior taught by their parents.
Some nondangerous insects have evolved with brilliant colorations that mimic those of dangerous and unpalatable insects. Once a chick has a negative experience with a colorful but dangerous/unpalatable insect, it will also avoid species that resemble the inedible insect but which may, in fact, be totally edible. It seems chicks only need to experience this distasteful and bitter experience once or twice and they never repeat their original mistake. Studies with Blue Jays, Common Grackles, and Red-winged Blackbirds have born this out.
tr>
Pyrrhuloxia by Richard at SearchNet Media
| |
Fruit- and Berry-eating Chicks
As young children, I presume most of us were taught by our parents or grandparents which berries were safe to pick and which noxious/poisonous berries to avoid. Prudent parents taught us to avoid picking and eating all the wild berries we came across in the field or forest for fear they could be dangerous, except for the few species we were told were safe and edible. However, most ripe fruits and berries are not likely to harm any animal that eats them, for their whole biological purpose is to be eaten by animals, which in turn disseminates the seeds, discarding them or passing them through the digestive system to germinate later. In this manner, wild fruits and berries are spread throughout the birds’ territory and/or range. This is one mechanism that nature relies on to ensure the continuation and proliferation of this type of food. If a fruit is poisonous or even disagreeable to any particular bird or animal, this is probably a chemical accident rather than an adaptation, as it is in the case of brightly protected insects.
Phanopepla by Doris Evans
|
In North America, poison ivy and mistletoe berries are known to be poisonous to humans and we learn to avoid these plants and their fruits. But birds can eat those berries with impunity, especially during winter when insects they may otherwise take advantage of are scarce or absent. Although it is seldom advantageous for plants to produce poisonous fruits, to have poisonous or otherwise inedible seeds is an advantage to birds; the fruits can be eaten and the seeds dispersed in the bird excrement, ready to germinate and produce more such plants. While the fruits and berries of many plants that birds eat have flavor and a minimum of carbohydrates, their seeds are packed with the more valuable and nutritious proteins and amino acids the birds require.
All seeds sold in our store, as opposed to grains found in most commercial mixes, are readily eaten by our backyard birds. But even seed-eating birds have their preferences. No birds, to my knowledge, will eat any or all seeds made available to it. We know that goldfinches prefer Nyjer thistle to the exclusion of all other varieties of seeds. Northern Cardinals, on the other hand, will eat a variety of seeds, particularly various sunflowers, safflower, and hemp. Additionally they will eat many species of tree nuts and peanuts as well as a wide variety of fruits and berries. They also take a limited numbers of insects and do become regular visitors to our insect meal, Nuts ‘n’ Bugs.
Learning to Drink
Gambel's Quail by Richard at SearchNet Media
 |
Somewhat surprisingly, chicks need to learn about drinking and bathing—it is not inherent behavior. Even if thirsty, they do not spontaneously drink when they first encounter water. They may be attracted to water by its sound or its visual allure. It is thought that a glittering single drop of water is enough to draw their attention. In addition to excellent vision, birds possess excellent hearing and can usually isolate the sound of a drop of water. It is probable that chicks learn to drink by tasting dewdrops on grass or raindrops on foliage.
Whatever exploratory accident allows a bird to first get water in its mouth, that water sets off an innate swallowing reaction, which in many birds includes the lifting of the head so that the fluid runs back into the throat. Some species require several such experiences before they really learn to drink and search out water sources. Birdbath drippers and misters, even a dripping outdoor faucet, will quickly attract the attention of a wide variety of species. While different species of birds are attracted to particular foods, water is a common need shared by almost all species. But birds need a longer time to learn about and become familiar with a transparent, elusive substance like water than with solid food they have become accustomed to while still in the nest.
Learning to Bathe: Parents Demonstrate, Chicks Learn
Screech owlets by Doris Evans
 |
Water-Bathing
The bathing movements of birds, like their drinking movements, are innate, but chicks must learn from experience in performing them. The methods birds first learn about bathing are diverse and fascinating to observe. Perhaps the most common method is the splash bath, where the bird enters shallow water and splashes it over itself by vigorous movements of the wings to distribute the water over and into the body of the bird, from time to time dipping its head in the water as well. Hummers will “shower” in mists from small waterfalls or misters set up in birdbaths or elsewhere in the backyard. They will repeatedly fly through mist, even stopping to hover in the mist until they are drenched. More dainty is the dip bath of the hummingbirds. With hovering wings blurred to our vision, hummers drop down into shallow water and partly immerse themselves in the water. Their bodies touch or remain in the water for only an instant, then repeat the same motion by rising a short distance and dipping again. Sometimes they will repeat this movement. Sometimes hummingbirds bathe by pressing against a saturated tuft of moss on vegetation, or by gliding with a depressed breast over the horizontal surface of a large or broad leaf in the early morning hours when it is still laden with dew or drops of night rain.
Dust-Bathing
Other avian species may bathe with slightly different versions of similar movements. But a minority of birds, particularly those from arid climates, will only employ a dry bathing technique called dust-bathing. Probably due to the lack of water in deserts and semi-deserts, these mostly gallinaceous birds scrape out a shallow depression in the sand or dirt and perform movements similar to those of water-bathing birds. Instead of water they become covered in dust which will “clean” their feathers of mites and other parasites. Some species, such as some wrens and sparrows, will bathe in both water and dust. While dust-bathing may not seem to be an effective method of cleaning from a human perspective, yet, after shaking out the dust that has worked its way into the plumage and preening afterwards, the bird is clean and refreshed. The dust bath is thought to control insect parasites by suffocating them. Some precocial chicks learn to dust bathe at a very early age. Some gallinaceous species have been observed dust-bathing just three hours after hatching.
Summary
While much more can be written about avian parenting and the learning processes that babies master, this article serves to introduce our readers to some of the relationships between parent and baby birds and some of the differences as to how birds learn what they need to thrive in the natural world—whether that knowledge is a result of inherent ability or learned behavior. Watching bird behavior in our backyards and at our feeding stations can inspire us to learn more.
Happy birding!
|
