Ornithology Ex2 P1

How does bird metabolism compare to that of mammals?

Birds have highest metabolism of vertebrates. Birds have a higher metabolic rate than mammals of similar size. Smaller birds have especially high metabolism relative to body mass, leading to faster water turnover and heat production. They lose water through excretion and evaporation but may use salt glands to help balance salt and water.

What is the evolutionary history of warm-bloodedness in birds?

Birds evolved from endothermic (warm-blooded) dinosaurs, which had body temperatures similar to or slightly lower than mammals. Like mammals, birds maintain a constant internal temperature (endothermic homeotherms), and their body temperatures are often higher than mammals.

What is Bergmann’s Rule?

In colder climates, warm-blooded animals tend to have larger body sizes to conserve heat.

A larger body size has a lower surface area-to-volume ratio, which reduces heat loss.
-This means less body heat escapes per unit of mass, helping conserve warmth in cold environments.
Example: Northern populations of birds are often bulkier than tropical ones.

What is Allen’s Rule?

Animals in colder climates have shorter appendages (legs, bills, ears) to reduce heat loss.

Shorter appendages reduce the exposed surface area, minimizing heat loss in cold climates.
Longer appendages increase surface area for heat dissipation in warm climates, aiding cooling.
Example: Arctic birds have shorter legs and bills than tropical relatives.

How do birds regulate body temperature in hot environments?

• Panting: Increases evaporation from moist surfaces in the respiratory tract, cooling the bird.

• Gular fluttering: Rapid vibration of the throat membranes (gular area) to promote evaporative cooling with minimal muscular effort.

• Evaporative cooling: Heat loss as water evaporates from the mouth, respiratory surfaces, or skin—important when air temperature exceeds body temperature.

• Defecation on legs / exposing legs or bill: Promotes evaporative cooling from exposed, unfeathered areas.

• Behavioral regulation: Seeking shade, spreading wings, or perching away from hot surfaces.

How do birds regulate body temperature in cold environments?

• Fluffing feathers: Traps air for insulation, reducing heat loss.

• Bill tucking / leg covering: Reduces exposed surface area to conserve heat.

• Huddling: Conserves body heat by sharing warmth with other birds.

• Countercurrent heat exchange: Warm arterial blood traveling to the feet transfers heat to adjacent veins returning cold blood to the body. This prevents excessive heat loss while maintaining circulation to extremities.

• Torpor: A short-term state of lowered metabolism and body temperature to conserve energy during cold nights or food shortages.

• Behavioral adaptations: Perching on one leg, turning back to wind, or roosting in sheltered spots.

What is countercurrent heat exchange, and how does it help birds stay warm?

Countercurrent heat exchange is a system in a bird’s legs that helps conserve body heat.

• How it works:

  • Warm blood flowing from the body to the feet (through arteries) passes right next to cool blood returning from the feet (through veins).

  • Heat moves from the warm arteries into the cooler veins, warming the blood before it goes back to the body.

  • This way, less heat is lost to the cold air or ground through the feet.

• Why it helps:

  • Keeps the core body temperature high while allowing the feet to stay just above freezing—enough to function without wasting energy.

  • It’s like recycling heat within the leg instead of letting it escape.

How does fat storage function in birds?

Birds store fat as their main energy source for flight and migration. Fat provides high energy per gram and can double body mass in a week before migration. Bird muscles are about twice as efficient as mammalian muscles at using fat for energy.

Main energy source: Birds store fat as their main fuel for flight and daily activity. It provides more energy per gram than carbs or protein.

• Migration: Before migrating, birds can double their body weight in fat. This fat is slowly burned for energy during long flights.

• Reproduction: Fat stores also help power breeding and egg production.

• Adaptation: Fat is lightweight but high in energy, which makes it ideal for flying animals.

What is citizen science, and what are its pros and cons?

Citizen science is public participation in scientific research.
Advantages: Large-scale data collection, promotes public education and conservation.
Disadvantages: Data may have biases (location, timing, skill level); must balance simplicity and usefulness.

What kinds of data come from citizen science projects like eBird?

eBird provides data on migration patterns, population trends, species distributions, and conservation insights based on public bird observations worldwide.

what are the major dietary/foraging strategies in birds?

• Granivory: Eats seeds and grains (ex: finches).

• Carnivory: Eats other animals (ex: hawks, owls).

• Frugivory: Eats fruits (ex: toucans).

• Omnivory: Eats a mix of foods like insects, seeds, fruit (ex: crows).

What is hyperphagia?

A period of rapid feeding before migration.
Birds eat constantly to build fat reserves and may raise metabolism or enter torpor to save energy

What is geophagy?

The eating of soil, clay, or sand to get minerals or help neutralize toxins from food, aids digestion, mineral supplement.

How do birds respond to changes in prey availability?

Birds adjust their feeding rate to how much food is around:

• Linear response: Eat steadily until full.

• Selective response: Feed fast at first, then slow as they fill up.

• Humped response (most common): Feed slowly when prey is rare, increase feeding as prey becomes common, then slow again when handling (the time and effort spent catching, processing, and eating prey) takes more time.

What is Optimal Foraging Theory?

Optimal Foraging Theory predicts that birds try to maximize energy gained while minimizing energy and time spent finding and handling food.
It explains three main things:

1. Prey choice: Whether a bird should attack a prey item it finds or keep searching for a more profitable one.

2. Search pattern: How a bird should hunt for prey — for example, some use Lévy flight, alternating short searches with occasional long flights.

3. Patch time: How long a bird should stay in one feeding area before moving to another, balancing food gain with travel costs.

what are examples of foraging strategies?

• Underwater pursuit: Foot-powered (anhinga); wing powered (puffin)

• Kleptoparasitism: Stealing food (frigatebirds).

• Hover-gleaning: Hummingbirds hover to pluck insects.

• Ambush/Stalking: Herons wait or sneak up on prey.
  Other examples: plunge diving, nectar feeding, scavenging, probing, flycatching.

How has the avian bill evolved for feeding strategies?

Bill shapes match diet:

• Crossbills: Curved bills to pry open cones.

• Hummingbirds: Long slender bills for nectar.

• Raptors: Hooked bills for tearing flesh.

• Ducks: Flat bills for straining water.

• Finches: Thick bills for cracking seeds.

Co-evolution between birds and plants (seed/pollen dispersal)

Birds and plants evolved together:

• Nectarivory: Birds (like hummingbirds, sunbirds) feed on nectar and pollinate flowers in return.

• Seed dispersal: Birds eat fruits, then spread seeds through droppings—helping plants reproduce.

• Adaptations: Birds have specialized bills and tongues for flowers; plants evolve bright colors or tube shapes to attract specific birds.

What is flocking, and what are its advantages and disadvantages?

Flocking is when birds group together while foraging, migrating, or avoiding predators.

• Advantages:

  • Increases safety from predators through “many eyes” watching.

  • Each bird has a lower chance of being attacked.

  • Can lead to better predator detection and quicker group responses.

• Disadvantages:

  • Causes more competition for food among flock members.

  • Crowding can increase aggression and disease spread.

What are mutualism and commensalism, and how do they affect birds?

• Mutualism: A relationship where both species benefit.

  • Example: Mixed-species flocks where different birds alert each other to predators or help locate food.

• Commensalism: A relationship where one species benefits and the other is unaffected.

  • Example: Small birds following large mammals or other birds to catch insects stirred up as they move.

What is mobbing behavior, and how does it work?

Mobbing is when multiple birds—sometimes of different species—swoop, dive, and call loudly at a predator.

• It’s a mutualistic defense behavior: birds work together to distract, confuse, or drive away the predator.

• The loud calls also recruit more birds to join the mob and warn others nearby.

What are social hierarchies in bird populations?

Social hierarchies are organized “pecking orders” within bird groups that determine dominance.

• Dominant individuals displace subordinates from food, perches, or mates.

• Subordinate birds yield to avoid aggression.

• This system reduces constant fighting because rank is established through displays or brief interactions.

• Hierarchies are common in flocking species or those with limited food resources.

what are the types of territories?

• All-purpose: Used for everything (feeding, mating, nesting).

• Mating/nesting only: Red-winged Blackbird.

• Mating only: Lekking species.

• Nesting only: Colonial waterbirds.

• Non-breeding: Feeding areas (e.g. Phoebes).

• Group: Shared by cooperative species.

• Roosting: Sleeping areas (e.g. crows).

What is territoriality in birds, and why is it important?

Territoriality is when a bird defends an area against others of the same species (and sometimes different species) to secure vital resources.

• The defended area is called a territory, and it may contain food, nesting sites, mates, or shelter.

• Territorial behavior includes songs, displays, chasing, or fighting to warn off intruders.

• It helps ensure birds have enough resources to raise offspring successfully.

• Territoriality often increases during the breeding season when competition for nesting areas and mates is highest.

• However, defending a territory requires time and energy, which can be costly if resources are scarce.

What is interspecific territoriality?

Interspecific territoriality is when a bird defends its territory against individuals of another species rather than its own.

• This usually happens when two species compete for the same resources, such as food, nesting sites, or perches.

• It can also occur if one species poses a threat to another’s nest or young.

• These interactions often involve aggressive chases, vocal warnings, or displays to maintain boundaries.

• Though less common than within-species territoriality, it helps reduce resource overlap and predation risk.

• Example: Red-winged Blackbirds defending nesting areas against grackles or marsh wrens.