How come my bun didn't shed any fur this Feb. to March 2018 time frame

So here's the sequence of events in the past 12 year:

My bun does NOT shed any fur in the Feb. to Mar. time frame at the very beginning when I first adopted her, she only does it in Aug.

Say 6 yr. ago, both of my buns begin to shed fur in the Feb. to Mar. time period, and they have been for the past 6 years

And now this current Feb. to Mar., my bun suddenly did not do any fur shedding

any particular reason for a rabbit decides not to shed fur? for that matter, what trigger a rabbit to shed fur at a certain time of the year?

My Rupert was having an awful moult about 2-3 weeks ago, then the weather went really cold and his moult stopped! So perhaps it is reliant on the temperature.

My bun now shed fur in April. I don't know why the delay. She's an indoor bun, so she won't know about the weather outside

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Daylight hours and changing temperature will still be noticed by an indoor animal. Just being indoors doesn't totally isolate them from the changing seasons, and they will moult in response to the same stimuli as outdoor rabbits - just probably not as much as they won't have the much thicker coat of an outdoor rabbit.