The high energetic demands of incubation in birds may be an important ecological factor limiting the evolution of life-history traits, such as clutch size. In biparental species, however, the demands of incubation may not be a major constraint because there may always be sufficient feeding time...

Variation in antipredation behavior should translate into variation in survival. Effective general defenses, such as predator avoidance, decrease the likelihood that an individual is attacked and should therefore reduce selection on behaviors that enhance probability of escape on attack. Escape...

Any animal whose form or behavior facilitates the avoidance of predators or escape when attacked by predators will have a greater probability of surviving to breed and therefore greater probability of producing offspring (i.e., fitness). Although in theory the fitness consequences of any...