So look for active aggression among males for this component Female choice component can look at female behavior and how females use differences in a behavior or an attribute to discriminate among males. So sexual dimorphism should be greatest in species in which males can monopolize many mates and least in species limited to one or two mates per breeding season. Prediction supported in many mammals. Two kinds of female choice that will be discussed Female mate choice and nuptial gifts. Females may be induced to mate with a male in return for some investment, usually caloric Black-tipped hangingfly choose males that give them a large edible nuptial gift.
Females prefer large edible insects.
Duration of mating is dependent on the size of the prey gift. Nuptial gifts may be spermatophore Decorated cricket has 2 part spermatophore. Female immediately detaches part. If its not big enough she finishes eating it before the rest has finished transferring sperm The larger the first part, the longer the sperm has to transfer. In birds its typical for males to migrate north or begin setting up territories even without migration before females do.