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How do birds decide which branch to land on?

How do birds decide which branch to land on?


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What factors do they weigh on? Shape, position of branch within the tree body/structure, fatigue, nearness to current position, etc.

And how fast does a bird's brain and nervous system decide on this?

Narrowing it down to a bird of prey, say the Harpy Eagle.


Why Do Bird Flocks Move in Unison?

Every autumn, flocks of birds begin to migrate to warmer territories. But how do they stay in such perfect formation?

The impressive, perfectly timed flight maneuvers of bird flocks, as well as their symmetrical group formation, can be summed up in a simple model, according to researchers from Budapest, Hungary.

The model determined that birds collectively switch from a flying state to a landing one, during which group action overrides the individual landing intentions of each bird, according to the study, published in the September issue of the New Journal of Physics.

While not all birds migrate, those that do usually head south how far south depends on the particular species, according to the Smithsonian National Zoological Park. Scientists have long tried to pin down the reason behind the timing of birds' migratory behavior, with theories suggesting birds' preference of eating fruit could drive the migration, or perhaps a requirement for non-forested environments.

Seasonal food scarcity is a more likely reason, according to ecologists at the University of Arizona in Tucson. After studying 379 species of migratory birds, the researchers determined that the number-one predictor that a species was about to migrate was a lack of food. The findings are detailed in the March 2007 issue of American Naturalist.

"If you are faced with food scarcity, you have two options," said W. Alice Boyle, an adjunct lecturer in UA's department of ecology and co-author of the study, in a statement. "You can either forage with other birds, or you can migrate."

While migrating bird flocks can be spotted during the daytime, most birds migrate at night (when the air is cooler and calmer, and there are fewer predators), flying in tandem even when they are 655 feet (200 meters) or more apart, according to a University of Illinois study published in the July 2008 issue of the journal Integrative and Comparative Biology.

Some birds, including swans, geese, cranes, pelicans and flamingos, form tight, V-shaped patterns, while others fly together in loose flocks. V-shaped formations help birds conserve energy, since each bird flies slightly ahead of the other, there is less wind resistance. To keep things fair, birds take turns being in the front, with each bird moving to the back when they get tired, according to the National Park Service.

Age, sex and body size also play a role in who leads the V-formation. In a flock of adults and young birds, juveniles usually do not lead since they are less able to maintain high speeds in lead position and would slow the entire flock down, according to a study by Swedish researchers published in the January 2004 issue of the journal Behavioral Ecology.

The researchers also determined that pelicans that fly in group formation beat their wings less often and have lower heart rates than those that fly alone. In this way, birds that fly in V-formation conserve much-needed energy during their long, difficult journeys.

This V-formation also enhances communication and coordination within the flock, allowing birds to improve orientation and follow their route more directly. In formation, every bird is accounted for, according to the Swedish study.

Got a question? Email it to Life's Little Mysteries and we'll try to answer it. Due to the volume of questions, we unfortunately can't reply individually, but we will publish answers to the most intriguing questions, so check back soon.


How do birds decide which branch to land on? - Biology

As humans, it is inevitable to believe that we are born into this world with an instinct an unknown conscious which is the means to our development. Without this instinct, many of the activities we take for granted would be a prioritized thought (i.e. breathing, sleeping, and walking). If humans were not born into this world with an instinct, everyday life would be a struggle because our minds would have to think each reflex through for every movement.

Many have argued that this development is due to nature rather than nurture. The idea that one is born with these abilities and as they grow older, they naturally start to become more accessible. Although many years of research has proved that while these instincts are given to us at birth, it takes exercising and motivation by parents to help babies reach their full potential of instinct. This idea is the nurture half of the argument, where people argue it is the responsibility of the parent to teach these children how to perhaps walk or eat properly. Similar to humans, birds are born with this same instinct, mainly for the action of flight. Now no bird is born with the ability to fly because it takes practice. Rather birds are trained by their parents through the power of reinforcement.

Let’s compare the flight of a bird to how a baby is trained to walk. One parent may stand on one side supporting the baby, while the other parent stands across from them holding something of value to the baby whether it is a toy or food. The idea is that the babies’ excitement to obtain whatever the parent has to offer, is what the baby uses as its motivation to leave the first parent and attempt to walk on its own. Obviously this will take a few trials because the baby needs to learn from its mistakes. Every time it will talk a little bit farther until it has finally reached the second parent.

This idea of reinforcement is very similar to that of a baby bird. The main source of motivation for baby birds is food. The baby bird knows nothing more than that at regular intervals their mother will come and drop some food off in their mouth. Slowly the mother bird will stand farther and farther away from the nest, forcing the baby bird to come out of the nest in order to get food. The bird realizes it needs this food to survive and this is the motivation for them to venture out onto a branch. Chances are the first few times the bird will fall down to the ground, but this repetitive process slowly becomes habitual to the bird. It will eventually learn that it can ease its falls by spreading its wings. The bird will become accustomed to this idea and every time it falls, it will attempt to flap its wings more and more. The result of not falling to the ground is something known as positive reinforcement. The result of not falling/ being able to fly its way back up to get food will motivate the bird to fly more often.

There have also been reports that parents will sometimes push a baby out of their nest. Perhaps the baby will not quite realize that it can’t survive unless it learns how to fly and becomes too dependent on their parent. Therefore the parent will forcibly teach them that unless they learn how to flap their wings, they are going to keep hitting the ground and will not get food. Once the bird has experienced flight for the first time, it does not make the second or third time very smooth. The bird will flail its wings clumsily and only sustain itself for a few seconds if that. Only with practice do they learn the ropes and develop the muscles necessary to flap their wings to their fullest potential.


Structure of Phylogenetic Trees

A phylogenetic tree can be read like a map of evolutionary history. Many phylogenetic trees have a single lineage at the base representing a common ancestor. Scientists call such trees rooted, which means there is a single ancestral lineage (typically drawn from the bottom or left) to which all organisms represented in the diagram relate. Notice in the rooted phylogenetic tree that the three domains—Bacteria, Archaea, and Eukarya—diverge from a single point and branch off. The small branch that plants and animals (including humans) occupy in this diagram shows how recent and miniscule these groups are compared with other organisms. Unrooted trees don’t show a common ancestor but do show relationships among species.

Figure 1. Both of these phylogenetic trees shows the relationship of the three domains of life—Bacteria, Archaea, and Eukarya—but the (a) rooted tree attempts to identify when various species diverged from a common ancestor while the (b) unrooted tree does not. (credit a: modification of work by Eric Gaba)

In a rooted tree, the branching indicates evolutionary relationships (Figure 2). The point where a split occurs, called a branch point, represents where a single lineage evolved into a distinct new one. A lineage that evolved early from the root and remains unbranched is called basal taxon. When two lineages stem from the same branch point, they are called sister taxa. A branch with more than two lineages is called a polytomy and serves to illustrate where scientists have not definitively determined all of the relationships. It is important to note that although sister taxa and polytomy do share an ancestor, it does not mean that the groups of organisms split or evolved from each other. Organisms in two taxa may have split apart at a specific branch point, but neither taxa gave rise to the other.

Figure 2. The root of a phylogenetic tree indicates that an ancestral lineage gave rise to all organisms on the tree. A branch point indicates where two lineages diverged. A lineage that evolved early and remains unbranched is a basal taxon. When two lineages stem from the same branch point, they are sister taxa. A branch with more than two lineages is a polytomy.

The diagrams above can serve as a pathway to understanding evolutionary history. The pathway can be traced from the origin of life to any individual species by navigating through the evolutionary branches between the two points. Also, by starting with a single species and tracing back towards the “trunk” of the tree, one can discover that species’ ancestors, as well as where lineages share a common ancestry. In addition, the tree can be used to study entire groups of organisms.

Many disciplines within the study of biology contribute to understanding how past and present life evolved over time these disciplines together contribute to building, updating, and maintaining the “tree of life.” Information is used to organize and classify organisms based on evolutionary relationships in a scientific field called systematics. Data may be collected from fossils, from studying the structure of body parts or molecules used by an organism, and by DNA analysis. By combining data from many sources, scientists can put together the phylogeny of an organism since phylogenetic trees are hypotheses, they will continue to change as new types of life are discovered and new information is learned.

Video Review



The Energy of Bird Flight

  • Contributed by Ed Vitz, John W. Moore, Justin Shorb, Xavier Prat-Resina, Tim Wendorff, & Adam Hahn
  • ChemPRIME at Chemical Education Digital Library (ChemEd DL)

Have you ever noticed that when birds land on a branch, they usually fly in at a low level and swoop up to the branch?

If they didn't do that, they would have to absorb all the energy of their flight with their legs (and strong wing action). But by flying upward, their kinetic energy of motion is converted to potential energy of increased height, so they slow down before landing, just as a rolling ball slows down when it goes uphill. Let's see how that works.

Kinetic Energy

Kinetic energy is energy due to motion, and is represented by Ek. For the bird moving in a straight line, the kinetic energy is one-half the product of the mass and the square of the speed:

m = mass of the object

Example (PageIndex<1>): Kinetic Energy of a Bald Eagle

Calculate the kinetic energy of a 6.8 kg (15 lb, about the biggest) bald eagle which is flying at 13.9 m s &ndash1 (about 30 miles per hour or 50 kilometer/hour their top speed) [1] .

(large E_ = frac<1> <2>m u^ <2>= frac<1> <2> imes 6.8 ext < kg> imes ( 13.9 ext < m> ext< s>^ <-1>)^ <2>= 657 ext< kg> ext< m>^ <2> ext< s>^<-2>)

The collection of units kg m 2 s &ndash2 is given the name Joule in the SI system after James Joule (see below). In other words the units for energy are derived from the SI base units kilogram for mass, meter for length, and second for time. A quantity of heat or any other form of energy may be expressed in kilogram meter squared per second squared.

Potential Energy

Potential Energy is energy that is stored by rising in height (in the case of birds landing), or by other means. It frequently comes from separating things that attract, like rising birds are being separated from the Earth that attacts them, or by pulling magnets apart, or pulling an electrostatically charged balloon from an oppositely charged object to which it has clung. Potential Energy is abbreviated EP and gravitational potential energy is calculated as follows:

m = mass of the object in kg

g = gravitational constant, 9.8 m s 2

Notice that EP has the same units, kg m 2 s &ndash2 or Joule as kinetic energy.

Example (PageIndex<2>): Height of an Eagle's Flight

How high would the eagle flying at 30 mph need to rise to come to a complete stop, if none of the stopping power came from wings?

Solution: The eagle's kinetic energy is 657 J (from EXAMPLE 1), so all of this would have to be converted to EP. Then we could calculate the height:

(large E_

= mgh = 657 ext < kg> ext< m>^ <2> ext< s>^ <-2>= 6.8 ext < kg> imes 9.8 ext ext ^ <-2> imes h )

This is 32 feet, so it's likely that some wing action is used to convert some of the kinetic energy to heat energy in the air to do some of the slowing down, so the upward motion is somewhat less.

Our reasoning here depends on The law of conservation of energy, which states that energy cannot be created or destroyed under the usual conditions of everyday life. Whenever there appears to be a decrease in energy somewhere, there is a corresponding increase somewhere else. If the bird's EK decreases as he slows down, his potential energy, or heat energy in the air, or other forms of energy must increase so that the total amount of energy does not change.

There are clearly many forms of energy, and it's tricky to define, but it's usually defined as the capability for doing work. For example, the flying bird could do work by crashing into a branch and breaking it (if it hadn't learned to slow down by rising), and could break the same branch by falling from a height, using EP.

We've left out one form of energy is very important to biologists and chemists. If the eagle started on the ground and at rest, it had no EP or EK. Where did the energy to move or gain height come from?

It comes from the eagle's diet of 250-550 grams per day [2] of food that can release chemical potential energy. We even measure dietary intake in Calories, where 1 Cal = 4184 J = 4.184 kJ = 1 kcal. The capital "C" that dieticians use for measuring the energy values of foods are actually kilocalories. The calorie used to be defined as the energy needed to raise the temperature of one gram of water from 14.5°C to 15.5°C but now it is defined as exactly 4.184 J. We know that food calories heat our bodies and allow us to do useful work (and maybe gain weight), and we'll see how they're measured, and consumed, in the next sections.

The first careful experiments to determine how much work was equivalent to a given quantity of heat were done by the English physicist James Joule (1818 to 1889) in the 1840s. In an experiment very similar to our eagle wing flapping example, Joule connected falling weights through a pulley system to a paddle wheel immersed in an insulated container of water. The moving paddles transferred the energy of the falling weight into turbulent heat in the water, just as an eagle's wings convert kinetic energy into turbulent heat in the air. This allowed Joule to compare the heat energy change of the water to the EP of the weights, and understand how energy of movement was related to heat energy.



The pressure exerted down by fast moving air (red arrows) is less than the pressure exerted up by slow moving air (green arrows).

If you tried the paper activity from the front of this article, you might have been surprised by what happened. In most cases a person would think the paper would go down and not lift up when they blow air across the top.

It may not be what you would expect, but it is what birds and planes do to lift off the ground and fly. Blowing faster-moving air above the sheet paper lowered the air pressure above the paper. Now the air pressure below the paper is higher and creates lift. Lift does exactly what it sounds like it lifts objects off the ground when everything is just right.


North American Breeding Bird Survey

The North American Breeding Bird Survey (BBS) is the primary source for critical quantitative data to evaluate the status of continental bird species, keeping common birds common and helping fuel a $75 billion wildlife watching industry. Each year thousands of citizen scientists skilled in avian identification collect data on BBS routes throughout North America allowing us to better understand bird population changes and manage them. The USGS Patuxent Wildlife Research Center, Environment and Climate Change Canada, and the Mexican National Commission for the Knowledge and Use of Biodiversity jointly coordinate the program, which provides reliable population data and trend analyses on more than 500 bird species.

Participate in the Survey - Each spring over 2500 skilled amateur birders and professional biologists volunteer to participate in the North American BBS. We are always looking for highly skilled birders to join the team.

Get Raw Data - Search and download raw data results

Strategic Plan for the North American Breeding Bird Survey, 2020–30 - The North American Breeding Bird Survey (BBS) has been the cornerstone of continental bird conservation and management for hundreds of North American bird species in the United States and Canada for more than 50 years. This strategic plan was developed in collaboration with key partners and stakeholders and charts the ambitious course for the BBS over the next decade (2020–30). Using this plan as a guide, the BBS program will set out to improve the breadth and depth of standardized data collection and analytical products ensure its products are widely used and recognized as the authoritative source for long-term population change information for most birds and secure adequate resources, internally and through partnerships, to realize the expanded vision of the BBS intended to support avian management needs through 2030.

The BBS Action Plan - A companion document to the Strategic Plan for the North American Breeding Bird Survey: 2020-2030, the BBS Action Plan identifies 28 specific actions for the U.S. Geological Survey, Canadian Wildlife Service, Mexican National Commission for the Knowledge and Use of Biodiversity and other possible collaborators providing a road map and starting points for accomplishing the three goals and eight strategic objectives of the BBS Strategic Plan over the next decade. The action plan is a living document, subject to annual review and updates as tasks are accomplished and priorities change through time.

Evening Grosbeak with BBS Trend Map (Credit: Mikey Lutmerding, USGS Patuxent Wildlife Research Center. Public domain.)

BBS Analysis - The North American Breeding Bird Survey (BBS) Summary and Analysis Website provides summary information on population change for >500 species of North American birds. The BBS provides data from 1966 for the contiguous United States and southern Canada (the “core” area), and the scope of inference expanded in 1993 to include additional regions in northern Canada and Alaska (the “expanded” area). The website provides geographic displays and quantitative information on population trend (interval-specific yearly percentage changes) and annual indices of abundance for each species at several geographic scales, including survey-wide, states and Provinces, Bird Conservation Regions (physiographic strata), and for individual survey routes in the United States. Custom analyses of population change allow of analysis of change for any combination of years over which the survey was conducted.

BBS Bird ID - The Bird Identification Infocenter is a collection of breeding and wintering distribution maps derived from North American Breeding Bird Survey and Christmas Bird Count data. Along with maps, images, song and call recordings, and life history information are provided for species encountered along BBS and CBC surveys.

Patuxent Bird Quiz - The Bird Identification Quiz was developed to allow users to test themselves on visual and aural identification of birds likely to be seen on North American Breeding Bird Surveys and Christmas Bird Counts. We also include a quiz in which users get to test their knowledge of wintering and breeding distributions of North American Birds.


Studying Feathers: How do scientists use Tinbergen’s four questions?

We’ve just used Tinbergen’s approach to look at feathers from several different perspectives—but it’s not just a learning exercise. Scientists like those in the evo-devo crowd, are making discoveries in just the same way, by linking findings from across the biological disciplines.

One such scientist is Kim Bostwick, who used this integrated approach to untangle the mysteries of a bird whose feathers work like a musical instrument. This may sound like an outrageous idea, but male Club-winged Manakins of Central and South America use a highly modified feather structure to play a powerful one-note tune. Strong evolutionary pressure on these males to attract females has made them unique in the bird world, but it took years of scientific investigation by Bostwick and colleagues to work out the full story of how and why these birds sing with their wings.

Singing wings

So how do they do it? Club-winged Manakins sing with their wings by rubbing specialized feathers together. One of these feathers is club-shaped with ridges along its edge. The adjacent feather is slender, and bent at a 45-degree angle. This bent feather acts as a pick, while its ridged counterpart acts as a comb to produce a one-note song. This method of producing sound is called stridulation stridulation <span act of rubbing together body parts to make a sound and also occurs in insects, such as crickets.

Kim’s story

Kim Bostwick began her study of Club-winged Manakins by asking questions about how they sing with their wings. She spent years piecing together how the birds accomplish this feat mechanically, but she did not stop there. Because Kim had always been interested in evolution, she also asked questions about how their specialized feathers and associated behaviors evolved. This led her to study other birds closely related to Club-winged Manakins to see what behavioral innovations occurred in their evolutionary history that contributed to the display we see today. It turns out that the behavior evolved through a series of small steps, including short wing clicks and backwards hopping, into one of the most unusual displays in the animal world. Like Niko Tinbergen, Kim is one of the many scientists who prefer to ask scientific questions from many angles, going beyond the mechanics to make discoveries about function, development, and evolution.

To learn more about Kim’s story at the Singing Wings website.

Further Learning

Watch a five-part video on the Club winged Manakin.
Interactive >

References

1. Heinsohn, R., Legge, S., & Endler, J. A. (2005). Extreme reversed sexual dichromatism in a bird without sex role reversal. Science. 309(5734), 617–9.
2. Perrone, M. (1981). Adaptive significance of ear tufts in owls. The Condor, 83(4), 383.
3. Prum, R. O., & Brush, A. H. (2002). The evolutionary origin and diversification of feathers. The Quarterly Review of Biology, 77(3), 261–295.
4. Zelenitsky, D. K., Therrien, F., Erickson, G. M., DeBuhr, C. L., Kobayashi, Y., Eberth, D. A., & Hadfield, F. (2012). Feathered non-avian dinosaurs from North America provide insight into wing origins. Science. 338(6106), 510–4.
Suggested citation: Cornell Lab of Ornithology. 2013. All About Feathers. All About Bird Biology <birdbiology.org>. Cornell Lab of Ornithology, Ithaca, New York. < add date accessed here: e.g. 02 Oct. 2013 >.

Acknowledgements:
Author: Mya Thompson
Web Designer: Jeff Szuc
Web programmer: Tahir Poduska
Illustrator: Andrew Leach
Content assistants: Marie Russell, Feven Asefaha


How do birds decide which branch to land on? - Biology

The discovery that birds evolved from small carnivorous dinosaurs of the Late Jurassic was made possible by recently discovered fossils from China, South America, and other countries, as well as by looking at old museum specimens from new perspectives and with new methods. The hunt for the ancestors of living birds began with a specimen of Archaeopteryx, the first known bird, discovered in the early 1860s. Like birds, it had feathers along its arms and tail, but unlike living birds, it also had teeth and a long bony tail. Furthermore, many of the bones in Archaeopteryx's hands, shoulder girdles, pelvis, and feet were distinct, not fused and reduced as they are in living birds. Based on these characteristics, Archaeopteryx was recognized as an intermediate between birds and reptiles but which reptiles?

As birds evolved from these theropod dinosaurs, many of their features were modified. However, it's important to remember that the animals were not "trying" to be birds in any sense. In fact, the more closely we look, the more obvious it is that the suite of features that characterize birds evolved through a complex series of steps and served different functions along the way.

In theropods even more closely related to birds, like the oviraptorosaurs, we find several new types of feathers. One is branched and downy, as pictured below. Others have evolved a central stalk, with unstructured branches coming off it and its base. Still others (like the dromaeosaurids and Archaeopteryx) have a vane-like structure in which the barbs are well-organized and locked together by barbules. This is identical to the feather structure of living birds.


At right, asymmetrical flight feathers are present in a fossil of a dromaeosaurid that may have had the ability to glide.

Another line of evidence comes from changes in the digits of the dinosaurs leading to birds. The first theropod dinosaurs had hands with small fifth and fourth digits and a long second digit. As the evogram shows, in the theropod lineage that would eventually lead to birds, the fifth digit (e.g., as seen in Coelophysoids) and then the fourth (e.g., as seen in Allosaurids) were completely lost. The wrist bones underlying the first and second digits consolidated and took on a semicircular form that allowed the hand to rotate sideways against the forearm. This eventually allowed birds' wing joints to move in a way that creates thrust for flight.

Birds after Archaeopteryx continued evolving in some of the same directions as their theropod ancestors. Many of their bones were reduced and fused, which may have helped increase the efficiency of flight. Similarly, the bone walls became even thinner, and the feathers became longer and their vanes asymmetrical, probably also improving flight. The bony tail was reduced to a stump, and a spray of feathers at the tail eventually took on the function of improving stability and maneuverability. The wishbone, which was present in non-bird dinosaurs, became stronger and more elaborate, and the bones of the shoulder girdle evolved to connect to the breastbone, anchoring the flight apparatus of the forelimb. The breastbone itself became larger, and evolved a central keel along the midline of the breast which served to anchor the flight muscles. The arms evolved to be longer than the legs, as the main form of locomotion switched from running to flight, and teeth were lost repeatedly in various lineages of early birds. The ancestor of all living birds lived sometime in the Late Cretaceous, and in the 65 million years since the extinction of the rest of the dinosaurs, this ancestral lineage diversified into the major groups of birds alive today.


How Birds Sleep

Like other animals that are active during the day, the principle nighttime activity of birds is sleeping. Birds choose how they sleep very carefully to ensure they can survive through the night, and they have certain tricks that help give them warning about predators or to protect them from the elements.

  • Many bird species choose cavities or niches to roost in at night, which prevents predators from having easy access to them. These same cavities also provide shelter from poor weather and may include bird roost boxes or empty birdhouses. Snags, dense thickets, and tree canopies are other common roosting spots. such as herons, egrets, and flamingos will sleep standing in water or on an island. The splashing sounds and wave vibrations of a predator coming toward them through the water acts as an instant warning system in case of danger.
  • Ducks, geese, and other waterfowl will float on the water to sleep, which gives them the same noise alarm system that wading birds take advantage of. These birds also often float in large flocks while they sleep, giving them a better advantage of numbers in case a predator approaches.
  • Small birds sleep perched high in trees, typically close to the trunk of the tree. The trunk holds heat from the daytime to provide better shelter, and the birds will be alerted to any vibrations or noises predators make if they climb the tree looking for prey.
  • Many birds, such as red-winged blackbirds and other gregarious species, form large roost flocks at night. This provides them safety in numbers as they sleep. Several birds on the edges of the flock may remain alert through the night to guard against predators or other threats as well.

How Do Birds Know How to Build Nests?

There are 10,000-plus species of birds in the world, about 1,100 species in the United States, and 350 or so in the greater Bay Area, so there is great variability in nests. But the basic purpose of any nest is to facilitate the raising of young, providing a functional and safe environment for both eggs and babies. (In some species, males also use nest building to attract females. Marsh wrens are a local example.)

There are many ways to accomplish this. Out on the Farallon Islands the common murre simply lays eggs on rocks our state bird, the California quail, scrapes a depression in the midst of concealing vegetation. Hooded orioles weave pendant nests that hang from the leaves of palm, sycamore, and other trees.

Now, if someone says that you eat like a bird, I’m not so sure that’s a compliment. Many birds dine constantly and poop almost as often. If they call you a birdbrain, though, I might take that as a compliment—although, of course, it depends on which bird they’re referencing. The psittacines (parrots, macaws, cockatoos) and the corvids (crows, ravens, jays, magpies) could be charter members of Mensa. They are super smart and well known for their intellectual accomplishments. Boobies, on the other hand…well, their mothers love them.

There’s been surprisingly little research done on nest building considering how essential it is to avian survival and to understanding bird smarts. For years, we saw it as a simply innate activity that was totally instinctual. A bird was born already knowing how to build a nest, end of story.But there have been some interesting recent studies of how birds learn and improve in their nest-making ability—and perhaps their reproductive success.

Several of these nest-building studies have examined captive zebra finches. They make great winged lab rats: they breed and build nests well in captivity, have short generation times, and immediately rebuild nests when their babies have fledged. They’re also passerines, or perching birds, which is the largest and most diverse order of birds —evolutionary success that may be partly due to effective nest building.

One study found that zebra finches will sometimes change their nesting material preferences in response to their success raising chicks in a given nest. In another study, they adjusted their building techniques to maximize available material, figuring out how to hold long pieces of nest material to fit them through the small entrance of their nesting area. And in the field, other birds have been observed to adapt and change methods between one nest and the next.

These studies indicate that birds can learn from their own nest-building experience, while other studies suggest birds may learn by example from their parents or other familiar birds. When building their first nests, some Baltimore orioles apparently observe more experienced, familiar orioles in their neighborhood and utilize the same nesting materials. This kind of dynamic is known as social learning, similar to what many mammals do.

There’s still an awful lot to learn here. Birds, for example, do not know what they are when they hatch they learn about their bird-ness through imprinting, or identifying with their parents during an important stage of their development. Could imprinting also play a role in learning to build a nest? How important is social learning in comparison? Do birds with A-plus nest-building skills also do better in other tasks? The research questions are endless.

As I write this I am in East Africa and, right outside my tent is a tree full of lesser masked weavers. The brightly colored males have created exquisite woven grass nests hanging from the thin, flexible branches of an acacia. They are dangling from their nests vocalizing and displaying for the females flying in. Pick me! Pick me! And at my house in downtown Santa Rosa a bushtit has woven yet another pendulant nest around the branch of a gnarled oak. Practice may not make perfect, but it sure can make a better nest.


Watch the video: Ο Κόσμος Των Ζώων - Τα Πουλιά (February 2023).