These times of year allow for the optimization of survival of young due to factors such as ambient temperature, food and water availability, and changes in the predation behaviors of other species.
[citation needed] Male seasonal breeders may exhibit changes in testosterone levels, testes weight, and fertility depending on the time of year.
Organisms generally time especially stressing events of reproduction to occur in sync with increases in food availability.
Photoperiod likely affects the seasonal breeder through changes in melatonin secretion by the pineal gland that ultimately alter GnRH release by the hypothalamus.
Some animals that are long day breeders include ring-tailed lemurs, horses, hamsters, groundhogs, and mink.
"Short day" breeders cycle when the length of daylight shortens (fall) and are in anestrus in spring and summer.