lecture 10 - antipredator defense in birds and mammals Flashcards
who is the main antipredator defense guy
tim caro
what is vigilance
animals examination of surroundings that occurs during other activities
what does vigilance come at cost of
feeding time
what is the most common def of vigilance
raising head above a certain level off the ground
how does being in a group help with vigilance
Key way to recover loss opportunity for foraging is to be in group so you can rely on other group members to take on burden of searching for predators some times
what is measured for vigilant behavior?
duration and rate
how should duration and rate of vigilance be varied
Prey can change either of these in response to predator
If predator attack at random, want constant interscan intervals to minimize predation
If predators catch on to the intervals and plan their attack around it, then prey should choose variable interscan intervals
what are the benefits of individual vigilance
- Increased prob to detect predator
- Can use behavior to look for competitors of same species during mating season
- Can use it to steal food from other people in your group
what are the costs of individual vigilance
- Decrease in foraging
- May give up sleep (and could make it harder to live)
- Cannot groom (for impalas)
does vigilance always decline with heterospecific group size
no
why don’t individuals cheat for vigilance
- If you aren’t vigilant you cannot escape as well
- Predators tend to select low vigilance individuals
- Individuals are vigilant so they don’t lose group members who contribute to dilution effect
what is the effect of group size on vigilance
Want bigger group because then the amount of time you have to search decreases and the probability of detecting a predator increases (plateaus at some point though)
