Ornithology Exam 2

Would adding feeders for hummingbirds and other birds alter bird migration?

No, adding bird feeders will not alter or prevent natural bird migration. Migration is primarily triggered by changing daylight hours and genetics.

Some birds of the same species migrate south of the US by crossing a large portion of the ocean (such as the Gulf of Mexico) or going to the same place by land. What factors must they consider when deciding to go by land or crossing the ocean?

Birds must weigh trade-offs between distance, energy expenditure, and physical endurance. A direct ocean crossing is shorter and saves time, but requires massive fat reserves and provides no opportunities to rest or refuel. Conversely, an overland route is longer and takes more time, but offers continuous food sources and shelter from severe weather.

Bird migration within South America is shorter and messier than in North America. What could be the reasons for that?

South America lacks the extreme seasonal temperature gradients of North America, and its complex topography encourages altitudinal and local movements rather than rigid latitudinal journeys. Additionally, the presence of vast, contiguous tropical ecosystems supports partial migration, nomadic foraging, and year-round residency rather than standardized continental flyways..

What experiment would you do to test if magnetism aids a bird’s navigation?

I would place migratory birds inside Emlen funnels during their migration season. By surrounding these enclosures with Helmholtz coils to artificially alter or reverse the local magnetic field, I could test if the birds adjust their directional attempts accordingly. If their orientation shifts in response to the manipulated magnetic field compared to a control group, it provides direct evidence that magnetism aids their navigation.

What experiment would you do to test if learning the position of the stars aids in a bird’s navigation?

I would raise young migratory birds in a controlled planetarium from hatching to their first migration, manipulating the simulated night sky to see if they rely on celestial patterns. By shifting the planetarium’s star rotation center (such as changing the position of Polaris), I could observe whether the birds’ directional orientation in Emlen funnels adjusts to match the altered sky. This demonstrates whether celestial navigation is a learned skill dependent on experience with the night sky rather than an innate mechanism.

Why is there a difference in the hippocampus between Semipalmated and Spotted sandpiper species, even though both are migratory?

The difference in hippocampal volume between the two species stems from their contrasting migratory routes and reliance on visuospatial memory. Spotted sandpipers travel over land, requiring a larger hippocampus (with significantly higher glial cell density) to store and process complex landmark, terrain, and foraging site information. In contrast, Semipalmated sandpipers complete much of their migration in long, non-stop flights over the featureless ocean, placing lower demands on landmark-based spatial memory.

Comment on one of the actions to manage the problem of migrant martins roosting in the industry buildings in the Amazon.

Managing migrant martin roosts on industrial buildings typically relies on non-lethal deterrents like adjusting exterior lighting or altering perches (like installing bird spikes) to safely redirect the flocks. Such measures help industrial facilities prevent sanitation issues while safeguarding the birds during their wintering stay.

The “Pious pelican” or “Pelican in her piety” symbolized Jesus’ sacrifice in medieval times. See the coat of arms of Louisiana. Explain that myth.

The myth holds that a mother pelican would pierce her own breast with her beak to feed her hungry chicks her own blood during times of famine, or even to revive them if they died. In medieval Christian symbolism, this self-sacrificing act was seen as an allegory for Jesus shedding his blood on the cross to give spiritual life to humanity.

Why do eggs need to be turned?

Egg turning is essential during incubation to prevent the developing embryo from sticking to the inner shell membrane, which would cause fatal malformations or death. Regularly rotating the egg also ensures even heat distribution and allows the embryo to properly access vital nutrients within the yolk and albumen.

In which situations do you expect eggs to have camouflage?

Camouflage in eggs is predominantly expected in species that nest in open, exposed environments, such as ground-nesting shorebirds or nightjars, where the eggs are directly visible to visually hunting predators. Conversely, species that hide their nests inside tree cavities, dark burrows, or deep domed structures face far less visual predation and typically lay unpigmented or plain white eggs.

What would happen if a bird’s eggs would be round as reptiles?

If bird eggs were spherical like many reptile eggs, they would easily roll off flat, elevated nests or cliffs where many birds lay their eggs. Additionally, round eggs cannot pack as efficiently under a brooding parent’s body as typical pyriform (pointed) or oval avian eggs, reducing heat transfer and increasing incubation failure.

What would be the advantage of some birds making their nests with spittle?

Using saliva allows birds like swiftlets to build nests on smooth, vertical surfaces like cave walls or sheer cliffs where traditional plant materials cannot rest. The saliva acts as a lightweight, quick-drying, and extremely strong biological adhesive that holds the nest securely in place while offering superior structural durability and protection from ground predators.

How would you test the hypothesis that pesticides cause thin eggshells?

To test this hypothesis, researchers could conduct controlled feeding experiments where captive bird populations receive regulated dietary doses of specific pesticides alongside an uncontaminated control group. Afterward, collected eggs from both groups would be measured for shell thickness and calcium content using precision micrometers or density analysis.

What should be the environmental requirement for birds like the ovenbird to make their nests with mud?

For birds like the ovenbird (and other mud-nesting species) to construct mud nests, the environment must provide a reliable, local source of fine-textured clay or silt soil mixed with adequate moisture. It also requires warm, low-humidity conditions or sheltered nesting sites to allow the wet mud to dry into a sturdy structure, alongside flexible vegetation or fibrous plant materials to serve as a reinforcing binder.

What do large macaws need to nest?

Large macaws require spacious, natural tree cavities, typically in large, old-growth hardwoods or palm trees, with deep hollows for secure egg laying and chick development. Because they cannot excavate their own hollows, they rely on pre-existing cavities created by decay or woodboring animals, as well as a rich surrounding forest that provides abundant seeds, nuts, and clean water.

Explain one strategy of deception; on how a bird would protect its nest

One common deceptive strategy is the broken-wing display, where a parent bird feigns injury by fluttering on the ground and emitting distress calls to draw a predator’s attention away from its nest. Once the predator follows the seemingly easy prey to a safe distance, the bird suddenly flies away unharmed, leaving its eggs or chicks undiscovered.

Describe how birds regulate the nest temperature if it is too hot or cold.

When it is too cold, parents incubate the eggs using body heat and rely on insulating materials like down feathers to trap warmth. Conversely, when it is too hot, birds shade the nest with their bodies, engage in panting or gular fluttering, or dampen their belly feathers in water to cool the eggs via evaporation.

What is the advantage of a bird that parasitizes nests?

By laying eggs in the nests of other birds, brood parasites avoid the massive energy and time expenditure required to build nests, incubate eggs, and feed demanding chicks. This frees the parasitic bird to allocate all its energy toward producing more eggs throughout the breeding season, significantly increasing its total reproductive output while leaving the risks and costs of parental care to the host parents.

What experiment would you do to test the following hypothesis:

Birds that nest in colonies recognize their chicks by sound.

I would perform a playback experiment by placing hidden speakers near the nests of colonial-nesting adults and broadcasting recorded vocalizations of their own chicks versus unfamiliar chicks. By measuring whether the parents selectively approach, call back to, or respond only to the audio of their own offspring, I could determine if they rely on acoustic recognition.

What are the advantages and disadvantages of nesting in colonies?

Nesting in colonies offers significant advantages, including enhanced predator defense through group mobbing and early alarm calls, as well as easier location of patchy food sources by observing foraging flock mates. However, the primary disadvantages include intense competition for local resources and nesting sites, increased vulnerability to disease and parasite transmission, and a higher risk of brood parasite transmission, and a higher risk of brood parasitism or infanticide from neighboring birds.

What is the purpose of some altricial chicks having a red gape?

A brightly colored red gape serves as a vivid visual signal that stimulates parents to feed the hungriest chicks, maximizing food delivery. Additionally, the intense coloration reflects high immune function and overall chick health, prompting parents to invest energy into their strongest offspring.

In which cases would cainism be a helpful strategy for survival?

Cainism, which is where an older chick attacks or kills its younger sibling, is an advantageous survival strategy when food resources are scarce, ensuring that available food goes to the strongest chick rather than being split so thinly that neither survives. It also serves as an effective reproductive insurance policy for the parents, who hatch a second egg in case the first fails, but allow the older chick to eliminate the “backup” if the primary offspring thrives.

What type of birds use helpers for caring for their young?

Cooperative breeding, where non-breeding adults act as “helpers” to raise young, is common in species like Florida Scrub-Jays, Acorn Woodpeckers, and Arabian Babblers. These helpers, often older offspring from previous seasons, assist the breeding pair with nest building, guarding against predators, and bringing food to the chicks. This behavior typically evolves in environments where suitable nesting territories or food resources are limited, making staying home more advantageous than attempting to breed independently.

How can we compare the brood patch in birds with something in humans?

A brood patch, where a bird sheds breast feathers and develops heavily vascularized, swollen skin, functions much like the skin contact during human skin-to-skin care given to newborns. In both cases, bare skin with rich blood flow is placed in direct contact with the offspring to maximize efficient heat transfer and regulate body temperature. Additionally, the heightened tactile sensitivity of a brood patch mirrors the sensitive skin of human hands and chest, allowing parents to precisely monitor heat and physical feedback.

Post three differences between altricial and precocial birds.

Condition at Hatching: Altricial chicks hatch blind, featherless, and completely helpless, whereas precocial chicks hatch with eyes open, covered in down feathers, and able to walk or swim shortly after emerging.

Parental care dependency: Altricial young require extensive, direct feeding and warmth from their parents for weeks, while precocial chicks can forage for their own food almost immediately under minimal parental supervision.

Brain and physical development: Altricial species hatch with smaller, underdeveloped brains that grow rapidly during the nestling period, whereas precocial species undergo greater embryonic development inside the egg, hatching with larger, more mature brains and physical body mass relative to egg size.

What is the trade-off in parental care efforts?

The fundamental trade-off in parental care is balancing the immediate energy and survival cost to the parents against the long-term survival and future reproductive success of their offspring. Investing heavily in a current brood reduces the parents’ own lifespan and future breeding opportunities, whereas withholding care saves parental energy at the direct expense of chick survival.

Who was David Lack, and what is he known for?

David Lack was an influential 20th-century British evolutionary biologist and ornithologist known for his groundbreaking field studies on bird ecology and population dynamics. He is most famous for formulating Lack’s Principle, which posits that clutch size in birds has been adapted by natural selection of the maximum number of young that parents can successfully feed and raise. He also made foundational contributions to the study of Darwin’s finches in the Galapagos Islands, demonstrating natural selection in action through beak size variations during droughts.

Enumerate different types of nests and give a species for each one.

Cup nest: A classic bowl-shaped structure made of twigs, grass, and mud, typically built in branches or bushes (American Robin).

Cavity nest: A hollow chamber built inside tree trunks, logs, or soil banks that offers protection from predators and weather (Eastern Bluebird)

Platform nest: A large, relatively flat structure constructed from sticks and twigs, often reused and expanded each year on high structures or trees (Osprey)

Pendant/Hanging nest: An intricately woven, sack-like pouch suspended from tree branches, usually entered through a small bottom or side hole (Baltimore Oriole)

Adherent/Spittle nest: A cup-like structure glued to vertical surfaces using saliva or mud mixed with fibers (Cave Swiftlet)

Scrape nest: A simple shallow depression scratched into the ground or gravel, sometimes lined with small stones, shell fragments or vegetation (Killdeer)

Dome/Mound nest: A covered, roofed structure built on the ground or in low vegetation with a side entrance (Marsh Wren), or a massive compost heap of organic decay constructed to incubate eggs via geothermal/fermentation heat (Mallee fowl)

Why did Jeremiah talk about storks?

Why do birds migrate?

Is migration just genetic?

What happened with the blackcaps in England?

What hormones might influence in migration and what evidence was found?

How are body resources used for migration?

What changes does RBTH do in their body?

Why were neonicotinoids considered safe and how did they use a bird to test a hypothesis?

How do Bar-tail Godwits migrate?

Why do small birds prefer to travel at night and big ones during the day?

How did God use weather to modify migration?

At what time do migrant harriers migrate?

How does the Tribute in Light affect migrant birds?

What can we do to ameliorate light pollution on birds?

Why did the dove return to Noah, but the raven did not?

What is the importance of the hippocampus and is it involved in migration?

Are the brains of hoarders different from the ones that don’t store?

What happens to migrating birds on cloudy nights?

What happens to the birds after a magnetic pulse?

If we alter the magnetic field parameters, mimicking migration time, what happens?

How are sex chromosomes in birds compared to humans?

Can we use birds to investigate sex-linked genes in humans?

Why do most female birds have only one oviduct?

How is the egg formed in the oviduct?

Any similitude with embryo formation in female humans?

What happens when a female bird must pair with an unattractive male?

How big should a clutch size be?

Do females “know” what the optimal number of eggs to lay is?

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What determined to have more or less eggs?

What was Martin’s hypothesis?

When does it pay host to accept brood parasites?

Does calcium matter for the eggs?

How do birds keep their nests clean?

What materials do birds carry to the nests to keep themselves healthy?

How did diclofenac in livestock affect vultures?

Why do birds leave the nest if the feathers are not ready?