Mares coming into season in winter?

[cob&onion]

Whats with all the mares coming into season in December?! both mine are in season and have gone daft and silly, and i know other mares that are in season too.
They never came into season last winter or the one before that either.........
Bonkers!

 

[Horses24-7]

Is it still fairly mild where you are? Horses reproductive cycles are controlled by temp/day light etc so it's probably due the weather being more milder than december last year. By controlling their cycles in this way it enables them to time foaling in the milder months and therefore giving their offspring the best chance of survival- quite clever really

 

[foraday]

The mares are all in season on our yard! All being flirty with the boys next door!

It's wildly mild for them! And we have our lights on anyway for the horses as we are bringing in a couple of the barren broodmares for covering in February/March. Normally we have the heat lamps on too but not needed as its so warm! They have been cycling quite well so far.