Trade offs

burd

What are the costs and benefits of migration in birds?

Migration is energetically expensive and risky (especially in storms), but allows access to food, better breeding habitat, and reduced competition.

Why do long-distance migrants like warblers and orioles migrate?

They are obligate insectivores; their food source disappears in winter.

How do short-distance migrants differ from long-distance migrants?

They are generalists and may migrate shorter distances or not at all based on resource availability.

Why do some birds migrate at night rather than during the day?

Night migration helps conserve energy, avoid diurnal predators, and use cooler temperatures.

What are the advantages of daytime migration for raptors?

They use thermals to soar efficiently and conserve energy.

What is the trade-off between productivity and survival in bird life history strategies?

Temperate birds have high productivity but low survival, while tropical birds have low productivity but higher survival.

How do migratory birds balance productivity and survival?

Migrants often have moderate productivity and survival, offering a balance between the two strategies.

What are the benefits of maintaining a bird territory?

Familiarity with resources and cover, and usually winning in conflicts due to homefield advantage.

What are the costs of territorial behavior in birds?

Time and energy spent defending the territory and risk if resources change.

How does food availability affect territory size?

Territories shrink when food is abundant and grow when food is scarce; birds may become nomadic if resources are too low.

What are the benefits of flocking behavior in birds?

Increased predator vigilance, reduced individual predation risk, and improved foraging efficiency.

What are the costs of flocking behavior?

Increased aggression, faster resource depletion, and competition.

What is the difference between altricial and precocial development in birds?

Altricial young are helpless and need care; precocial young are mobile and self-feeding at hatch.

What are key features of altricial birds?

Closed eyes, no thermoregulation, small eggs, fast growth, large intestines, low parental egg investment.

What are key features of precocial birds?

Open eyes, mobile at hatch, large eggs, slow growth, small intestines, high parental egg investment.

Why do birds maintain high body temperatures?

To improve reflexes, nerve speed, muscle strength, and endurance.

What are the costs of maintaining a high body temperature in birds?

Energy expense, risk of overheating, and increased protein breakdown.

How do birds manage water balance?

By obtaining water from food and metabolism, especially from fat breakdown.

How energetically costly is egg production for birds?

40–50% of BMR in land birds; 124–180% in species with precocial young.

What is parent-offspring conflict?

Parents aim to survive for future breeding; offspring aim for maximum care now, creating a trade-off.

What does Lack's Hypothesis suggest about clutch size?

Clutch size is optimized for the maximum number of young parents can feed.

What is bet-hedging in clutch size?

Laying fewer eggs than the maximum to conserve energy and improve future survival.

What is the difference between synchronous and asynchronous hatching?

Synchronous = all chicks hatch together; Asynchronous = staggered hatching, which may cause brood reduction.

What is brood reduction?

The intentional or passive loss of some chicks so parents can focus on the healthiest ones.

How does egg pigmentation relate to bird nesting strategy?

Pigmented eggs cost more energy; unpigmented eggs are common in cavity nesters.

Why are some bird eggs pointy?

Pointy eggs roll in circles (not off cliffs), may aid in heat transfer or compact egg arrangement.

What is the Tissue Allocation Hypothesis?

Fast-growing altricial chicks allocate energy to growth over tissue maturity.

What are the pros and cons of rapid nestling growth?

Faster fledging to escape predators vs. higher feeding demands on parents.

How do brood parasites benefit from their strategy?

They avoid the cost of parental care and often outcompete host chicks.

How do hosts suffer from brood parasitism?

They invest resources in raising unrelated chicks, reducing their own fitness.

What is the relationship between fecundity, mortality, and age at maturity?

Higher mortality leads to earlier maturity and higher fecundity.

Why do birds use multiple navigation cues?

Redundancy increases accuracy and provides backup when one cue fails.

What are some navigation cues birds use?

Visual landmarks, solar and stellar cues, geomagnetic fields, and smell.

What are benefits of urban ecosystems for birds?

Nesting sites, food sources (feeders), water features, and habitat diversity.

What are direct threats to birds in urban areas?

Collisions (especially windows), pesticides, and disease.

What are indirect threats to urban bird populations?

Habitat loss, climate change, and invasive species.

Why is cat predation controversial in bird conservation?

Domestic cats cause high bird mortality but are culturally protected.

What is molting and why is it costly?

Feather replacement is energy-intensive, especially for flight feathers.

What is the advantage of simultaneous molt in geese and swans?

Faster process, though it causes a temporary flightless period.

Why are molting and breeding separated in time?

Both are energy-intensive and usually don’t occur simultaneously.

What are common camouflage strategies in bird plumage?

Cryptic coloring, countershading, and disruptive patterns.

What plumage patterns help with signaling?

Bold or repeating patterns, reverse countershading, and black-tipped wings.

Why do forest birds tend to have low-pitched, simple songs?

Low frequencies travel better and are less affected by vegetation.

Why do open-habitat birds use high-pitched, complex songs?

These are better suited to less obstructed environments.

What are ventriloqual alarm calls?

High, thin, long calls that are hard to locate, used to alert others without revealing position.

What is the benefit and drawback of large song repertoires?

Helps with mate attraction but makes location-based communication harder.