@jengosmonkey supposedly about 5 % of litters are born out of season. Out of the normal time of year for that hemisphere. I had two litters into the data base yesterday, born in Australia in November and January.
I loved summer litters, Hoover and her sisters were born in July as were Firbi and his siblings. I put them all into a big black bucket used in the garden for weeds and carried them around to the main lawn where they had great fun and games. Firbi was born in 2000 and Hoover in 2008.
Plessy was born in September, mother of Firbi. Her first litter was born in April. She only ever had a token dribble with the other girls in Autumn.
Made life as a breeder very interesting. My first ever litter was born in April, out of a bitch whose sire had been imported from Australia by VTW. Veronica Tudor Williams.