 Another is Phoenix Park in Ireland where a herd of 400–450 fallow deer descends from the original herd introduced in the 1660s.Fallow deer are highly dimorphic, polygynous breeders the breeding season or rut lasts approximately 135 days.In the Northern hemisphere the breeding season tends to occur in the second half of October, while it occurs in April in the south, some matings can still occur before and after.