For the past fourteen winters I've followed the fortunes of over-wintering Purple Emperor larvae in the wild, mainly in Savernake Forest, Wilts. More recently, I've studied larvae at an isolated site on the Lambourn Downs, W Oxon, and in my local woods, Cirencester Park Woods, where the butterfly was discovered in 2020.
Losses, primarily to avian predation, have generally been high (in the 50% to 75% bracket mainly). Obviously, my sample sizes have varied.
This winter I have recorded Zero Loss in Savernake, albeit out of a small sample of five, and Zero Loss in Cirencester Park Woods, out of a sample of eight. That is MEGA. This is the first time I've not recorded any losses in Savernake (from viable samples).
I don't rightly know why, but it does seem that when Great Tit populations (in particular) are down, Emperors go up. Woodland Great Tit numbers seem to be currently low. Also, the cold spell in early December may well have shocked various predatory invertebrates into proper hibernation.
So, if the spring is clement and if the weather is kind during the critical pupation and pupal periods 2023 could see a very good Emperor season, at least away from places in the Southeast and East of England where sallows droughted off last July and August.
Watch this space...
Obviously, the wet March has kept larvae abed a while longer, but they are now nearly all lined up against Sallow leaf buds, waiting for them to open so that they can start to feed. One of two have jumped the gun and have bitten into loosening leaf buds, like this one (Cirencester, April 1st) -
Most of them are in this mode (this is 'Cincinnatus', from Cirencester Park Woods, on March 31st) -