The timing of mating also varies among species. Most frogs breed at night. Most birds breed during the day. Zebras breed year round. Garter snakes mate in the spring.
Timber rattlers look for mates in the fall.
One challenge for ecologists is to collect information about when, where and how mating occurs, and then find out if and how parental care is expressed. Each new discovery can add insight into our understanding of the relationships among the ecology, evolution and breeding pattern of the species. A study of a tropical frog found in Guyana, South America, provided evidence that an individual animal's actions may be best for propagation of that individual's genes but are not necessarily what's best for the species. The female frogs vary in body size and, if given a choice, will select male mating partners that are about four-fifths their own length. Experiments revealed that this size ratio of female to male produced the highest fertilization of a female's eggs.