Caught a 66lb beaver earlier this week and was disappointed that the castors were mostly empty. The shell itself was huge but not much in them. This is my first year trapping spring beaver and have read that castors are usually larger in the spring, have caught them in the fall with decent amounts of castor.

Anyone know what causes castors to be empty? Or why castors are supposed to be larger in the spring?

Spring castors here are no better I did see some nice ones my student caught might be a location thing.

In my experience the fullest castors are just at the onset of breeding season. But mostly there is extreme variation between beavers as to how full their sacs are. Often times an older female will have large scantly filled pods. But then again sometimes they will be nicely filled.

Where beavers are plentiful and are moving around a lot I seem to get the biggest castors. i.e. big river beaver.


Colony beaver on small streams seem to have smaller castors. I equate it to how much marking they need to do to protect their territory.

Any idea of how much castor they produce? Do those sacs fill up and emptied every week or month? If I would have caught this one a mile upstream would it be full?

I don't know how you could ever really determine that. My experience leads me to believe that some beavers just have more filled up castors than others. Genetics likely.

I do know that people I sell castor to say my section of castor is about the best they have seen. Not just size and how filled the pods are but that the color of the pods is lighter.

I usually average about 20-25 lbs of dried actor for every 100 beaver.

I'm thinking it was a female. Some of the big females I catch only have shells. Many have decent castors, but I have had some that were mere shells.

[quote=beaverpeelerI usually average about 20-25 lbs of dried actor for every 100 beaver.[/quote]

My average down here would be more like 10 - 12 pounds for every 100 beavers. I catch a lot of two year olds that repopulate old sites around this time of the year.

Caught a bunch under the ice Jan/Feb and they all had shells with very little castor in them. All sizes thought it was kind of odd.

collecting skunk essence is much the same as far as what is in the pods..you just never know

Yes it was a female. Picked up a 50+ pound male today in the same area. Castors were a little fuller but not by much. These are river beaver.

Read in a book about beaver it is all about hormones a lot of beaver competing for the same turf full of castor they make it as fast as they use it. One generation of beaver no completion little castor produced.

Caught an old beaver on a pond. Supposedly it had lived there a long time... New property owner wanted it gone. It was full of old cuts and wounds. Chunks missing out of tail. Nibbled ears. Old knots and scars in the pelt. The castors were darn near hard. I saved em. Dried em. Couple old time trappers told me that is the best kind of castor. they called it “bark stone” I have no idea if that’s true. But never caught another with hard castors. Different levels of fullness, shells... but never hard