Perhaps fluctuation in temperature? Might be below freezing?
At around plus 5 Celsius you can see some bees taking flight,
if there is no activity at around 10C, then the hive is dead.
It's hard to know why they die without inspecting, it could be
due to Varroa mites, foulbrood and other diseases, if they
lasted for 8 years on their own you did very good!
..
Konrad

if they are dead wouldn't there be signs of other life feeding on them? (flies or insects coming out of the entrance)

It was probably below -5 this year but the activity I saw was after that weather had passed.

Maybe they were survivors and the queen had died?

By the way ,just looking at your page, I see you have cherry trees that seem to be giving a good return in a cold climate.

Also they seem to be a nice manageable size (for netting)

Would you have the name of the variety?

I do have a couple of cherry trees (ornamental)but they are very big and only have a few cherries that get eaten by the birds...

>>Maybe they were survivors and the queen had died? Yes, this is possible, then the hive will die out and most likely sooner or later this old hive will attract new colonies, [in swarm season].
And if hive died from a disease, then it can spread to other colonies, that's why it's important that hives are inspected regularly.

>>By the way ,just looking at your page, I see you have cherry trees that seem to be giving a good return in a cold climate. Also they seem to be a nice manageable size (for netting) Would you have the name of the variety? The name is on top of picture, Evans, tart, sour or pie cherry, we can only grow sour cherries in our cold climate, this is a excellent cherry, the tree is very short, shrub like and most can be picked from the ground.
They grow on their own root, suckers can be dug up and transplanted.

It's good to have wild berries for birds, I grow allot too.

Konrad