year-round mating season
Used in biological or zoological contexts to describe animals that are in heat or capable of breeding throughout the year. Often applied to domesticated species like cats or rabbits, or humorously to humans.
Cats are sometimes said to be animals with a year-round mating season.
Rabbits are in a state close to year-round estrus.
Refers to a specific mating season or period of estrus, not necessarily year-round.
Compound of 年中 (ねんじゅう, 'all year') + 発情期 (はつじょうき, 'mating season'). The reading ねんちゅう is a common variant of ねんじゅう in compounds.