Birds building nests is a common sight, especially during springtime when birds are preparing for breeding season. But is this complex nest-building behavior something birds are born knowing how to do, or is it a learned skill? The answer is that nest building is driven by instinct, but it also involves learning. Birds are born with the urge to build nests at certain times of year, but they gain building skills through experience.
Is Nest Building an Instinctive or Learned Behavior?
Nest building is triggered by hormones and the bird’s biological clock. It is an innate behavior, meaning birds do not have to learn how to build nests. The urge arises at certain times of year, such as when it’s time to breed. This is evidence that genetics and biology play a central role.
However, the skill of nest building is honed over time. Young birds on their first nesting attempt build simpler, sloppier nests. With age and experience, their building technique improves. Studies of weaverbirds in Africa showed that the first nests built by young males were smaller and messier than nests built by older males. This indicates learning is involved too.
So while the desire to build a nest comes from within, birds rely on learning and memories to translate this desire into the actual construction of an intricately woven nest. It’s a combination of nature and nurture.
Evidence That Nest Building is Instinctive
Here is some of the evidence that nest building is driven primarily by instinct:
- Nest building is triggered by hormonal changes. Increasing day length in spring causes the release of hormones like gonadotropin and prolactin, which activate nesting behavior.
- Hand-reared birds with no parents to teach them how to build a nest can still construct nests when hormonal triggers kick in.
- Nest building peaks during breeding season. Birds living in controlled captivity with fixed photoperiods and access to food still begin building nests at certain times of year, showing an internal clock drives the behavior.
- Nest building is common across diverse bird species. Very different types of birds construct very different types of nests. This points to an innate origin not learned behavior.
These examples show birds have an innate biological drive they are born with that compels them to build nests during the breeding season. The urge is created by hormones and annual cycles.
Evidence That Experience Plays a Role
At the same time, research indicates nest building depends on learning and experience too:
- Young birds build sloppy nests at first that improve with practice. This skill development points to learned skills.
- Birds deprived of nesting material early in life build poor nests later on, showing the need for early learning opportunities.
- Nest design varies regionally. Different populations of the same species build different style nests, suggesting birds learn local building techniques.
- Birds incorporate new materials into their nests, revealing the capacity to learn new methods.
These examples show that while the drive to build a nest comes from within, the bird relies on experience to refine the actual construction process. Learned skills allow the bird to translate an instinctive urge into a finely crafted nest.
How Do Birds Learn Nest Building Skills?
If nest building involves learning, how exactly do birds acquire their construction skills? Research points to several ways baby birds start building their nest repertoire:
Trial and Error
Young birds improve at building nests in part through simple trial and error. Their early nesting attempts are clumsy but they get better by making mistakes, adjusting, and practicing. The same way humans learn any complex skill, birds use trial and error to hone their technique. Each year, their nests become more sturdy and weather resistant.
Observing Parents and Other Birds
Birds aren’t born knowing what materials to use for their nests. By observing their parents and other birds in the region, fledglings learn which vegetation, twigs, and fibers make suitable nesting material in their habitat. Different bird species are adept at building nests with specific local materials. This knowledge is acquired by watching others.
Innate Preferences
Genetics gives birds innate material preferences that guide their nest construction. Studies show even hand-raised birds with no nest experience preferentially choose certain plant fibers for their first nests. This shows an element of innate knowledge guiding their choices. It’s not all learned by observation. Biology predisposes them toward certain vegetation.
Teaching By Parents
There is some evidence parent birds actively give demonstration lessons in nest building. In some species like weaverbirds, the female starts the nest and the male observes before taking over construction. This observation phase may function as a teaching method. Parents may also bring material choices to their young, giving hands-on guidance.
Why is Nest Building Partly Inherited and Partly Learned?
The combined influence of instinct and learning on nest building makes evolutionary sense. A completely inflexible, inheritable nest building program would not serve birds well. The environment differs across regions and habitats, so an inborn blueprint would often produce poor quality nests.
At the same time, nest construction is too complex and specialized to depend entirely on learning. It takes time and requires coordination. Leaving it purely to trial and error could produce low breeding success.
The hybrid inherited-learned approach maximizes success. An internal drive ensures nests get built. Learning allows birds to tailor building methods to local conditions. Together, instinct and experience produce well-constructed, adapted nests.
Local Adaptation
Because nest construction skills are partly learned, birds can adapt their nests to different environments. Desert birds incorporate thick, insulating material. Tropical birds weave hanging nests that give protection from predators. Sea birds nest on cliffs. This local adaptation contributes to survival.
Reliability
If nest building was only learned, some birds might fail to pick it up and produce no nest. But because all birds have the inner drive, it happens reliably each year. Inheritance makes sure the behavior consistently occurs.
Efficiency
Trial-and-error learning alone would mean birds waste time testing poor construction methods before discovering what works. Instincts guide them toward suitable materials and techniques so efficient nests can be built quickly. It saves resources.
Flexibility
Since parts of nest building are learned, birds have flexibility to change techniques, experiment with new materials, and improve methods over a lifetime. This flexibility and creativity helps produce robust, specialized nests.
Examples of Bird Species Demonstrating Inherited and Learned Nest Building
The interplay of instinct and learned skills can be seen across diverse bird groups:
Weaverbirds
These African birds weave intricate hanging nests from grass and strips of leaves. Males build the nests to attract females. First attempts by young males are smaller and messier, showing inexperience. But they have an innate drive, since even isolated males construct nests at certain times of year.
Songbirds
Many songbirds such as finches build cup-shaped nests. Nesting skills develop with age, but hand-reared birds without exposure to nests still attempt them in spring, driven by hormones. Local populations build nests suited to their habitat, indicating learned adaptation.
Hummingbirds
Hummingbird nests are tiny, soft cups made of plant down, spider webs, and lichens. Their skill at nest construction develops over time, but even young birds innately prefer certain materials. Nest styles also differ across geographic ranges, suggesting learned local adaptations.
Woodpeckers
These birds drill cavities into trees to create nest holes. The size and placement of cavities improves with experience. However, even juveniles reared apart from adults will core out holes in trees at certain times of year, showing this species has a built-in motivation for cavity construction.
Seabirds
Seabirds like albatrosses display a strong innate drive to build nests each breeding season, but construct them with different techniques. Some nest on cliffs, others on the ground, and some build raised mounds, indicating learned responses to local conditions.
Conclusion
Evidence shows that in birds, nest building is sparked by an inherited, hormonally-driven urge that arises each breeding season. No learning is required to motivate this behavior, which occurs reliably across diverse species, environments, and individuals. However, research on birds also demonstrates that the specific skills required to build a sound, well-designed nest are learned over time through trial and error experience and observation of other birds. The outcome is locally adapted, specialized nests constructed each spring by birds combining their innate drives with learned construction techniques. The balance of genetic programming and intelligence acquired through experience produces successful bird nests optimized for survival.
