Different species of crickets have different calling songs with different characteristics, e.g., inter chirp interval, pulse repetition rate, etc.
Herring gulls breed is large colonies on the ground and defend territories.
The Kittiwake also breeds in colonies but nests on vertical cliffs and its nest pad is its territory and breeding site. It is true that killing infants is not, in the short term, an effective means of increasing population numbers of a species. Given the situation for both male and female, the observed behaviors make sense in terms of propagating ones genes . The optimality approach to the analysis of behavior attempts to builds models where different behaviors are treated as the traits and asks which one of these behaviors might evolve. Frequency dependent models are ones where the strategy of one type depends on the strategies and frequencies of other types in the population.