Behavioral Ecology

Levels of Behavior Explanation
- Proximate Causes (Immediate): Refers to how behavior occurs (mechanism).
- Ultimate Causes: Explains why behavior occurs (evolutionary and historical reasons).
Natural Selection: Survival and reproduction are influenced by behavior, favoring traits that enhance foraging, mate acquisition, and predator avoidance.
Adaptive Evolution: Traits conferring reproductive or survival advantages increase in frequency if heritable.
Behavioral Adaptations:
- Cockroaches evolved glucose aversion due to selective pressure from traps (Silverman and Bieman, 1993).
Genetic and Environmental Influences: Behavioral traits can be influenced by both genetics and environmental factors.
- Oldfield Mice: Build complex burrows possibly due to open habitat; Deer Mice: Simpler burrows in protected areas.

Foraging: Animals adjust their foraging strategies based on food availability and energy maximization.
- Optimal Foraging Theory: Assumes animals maximize net energy gain. Profitability (P) is defined as energy (E) relative to time (t) spent obtaining food.
- Success in foraging increases with energy invested but plateaus (risk of diminishing returns).
Field Studies Supporting Foraging Models:
- Great tits prefer larger prey when profitable.
- Eurasian oystercatchers select prey within a specific size range, avoiding too small or large bivalves.
- Marginal Value Theorem: Suggests an animal should leave a food patch when the rate of energy return drops below the average for the habitat.
Risk Management in Foraging:
- Presence of predators (e.g., wolves and elks) impacts foraging behavior; animals may prioritize safety over food availability.
- Small bluegill sunfish increase foraging time in protective vegetation when predators are present.
- Song sparrows reduce feeding frequency when exposed to predator sounds.

Sexual Selection: Traits that improve mating success can be selected.
Sex Differences in Mate Selection:
- Males may possess extravagant traits to attract females.
- Female mate choice can lead to the evolution of long tail feathers in widowbirds, supporting sexual selection hypotheses.
Direct and Indirect Benefits of Mating:
- Males may provide resources (food, territory) or genetic benefits through desirable traits (handicap hypothesis, sexy son hypothesis).
Reproductive Potential Disparities: Males typically produce more offspring; females are usually selective to protect their investment into offspring.
Mating Systems:
- Monogamy: One male and female pair.
- Polygyny: One male mates with multiple females.
- Polyandry: One female mates with multiple males, often linked to parental care dynamics.
- Promiscuity: Both sexes mate with multiple partners.
Ecological Influence on Mating Systems: Availability and spatial arrangement of mates and resources can dictate mating strategies.

Benefits of Group Living:
- Reproductive Success: Particularly when males control high-quality territories.
- Cooperative Behavior: Sharing feeding and caring for offspring reduces individual risk of predation.
- Increased Foraging Efficiency: Predators (e.g., lions, wolves) can execute cooperative hunting strategies.
Cost of Group Living:
- Increased competition for limited resources as group size increases.
- Disease and parasite transmission can rise in larger groups.
Optimal Group Size: Balance between maximizing benefits of group living and minimizing resource depletion or competition.

Lion Social Structure: Adult females in prides cooperate in care and hunting, but males may engage in infanticide.
Behavioral Adjustments Due to Predators: Song sparrows modify their behavior and feeding rates based on perceived predation risk, demonstrating alteration of fitness due to fear.
Fruit Fly Egg-laying Strategies: Female fruit flies may lay eggs in alcohol-rich foods to protect larvae from parasitic wasps, showcasing adapted survival strategies.
Ecosystem Impacts of Predator Responses: Altered foraging behaviors due to the presence of predators can significantly affect ecosystem processes and nutrient cycles.