We're talking about rodents and birds, primarily. In all years, there will be "theft"; but this year it seems to be exceptional to us. The nuts are disappearing.
In our experience, less experienced hazel growers tend to see hazel bushes with few nuts, and assume the bush simply never had many. Often this is not the case- predators remove them; and very stealthily, so the gradual loss is not noticed.
As a reminder; one of the papers I submitted for my Masters was an original piece of Ethology; a summer long field study of Black Tern social behavior- I basically minored in Animal Behavior, and am a trained observer.
Which has turned out critically important on several occasions; in one, it took us weeks to discover that bluejays had deciphered our plant marking process- and were using it to harvest the best nuts, and best plants, before we actually got to them. Sounds hard to believe; but we proved it. Amateur observers would not have noticed the jays' behavior- it was silent, (very unlike jays) concentrated (25 jays in a flock) and limited to very early morning hours only- when humans were not in the field, because of heavy dew.
A couple of years later, our local crows started behaving similarly; though they did not need pre-marked plants; and their restriction on time in the field was even more acute- they started specifically at sunrise, and left the fields before any humans were (normally) out of bed. I discovered this by following the rules of animal behavior research- get out and watch, until you find out- all night if necessary.
We teach numerous ways to intercept nut thieves in our Short Course; but the #1 tool is "Be Aware!" - and take action of some kind; most effectively quick harvest. The nuts can disappear rapidly once the thieves get focused.
We think this year is exceptional because of the drought. Corn usually abundantly available to crows is far less available, and often of poor quality- the animals are hungry, and the hazels may represent the only easy food source available for miles.
This photo was taken by Brandon, one morning a few days ago. If Blogger is working right, you should be able to click on it and get access to the full file size. If you zoom in- the crows become visible.
This photo is a "blow up" of the previous one, doctored with editing software to bump up contrast and sharpness; so the crows can be seen. If you do the same to the rest of the photo- there are about 30 in this one snippet, about 100 crows in the entire picture when you count; Brandon estimated only 60...
They only flew and revealed themselves when Brandon responded to 2 watch crows, and "chased them". Two calling crows turned into a flock of 100 hiding birds. .
REALIZE- YOUR CROWS KNOW YOU. They watch you. Do you hear a crow cawing a minute or so after you step outside? That's the "watchman", telling the others you're moving. No, I'm not making this up, or delusional- crows are extraordinarily intelligent, as researchers have finally been documenting in the past few years.
That's one of the few good points to crows- ours know for a fact that we will shoot them if we have the least chance. They also know we go to great lengths to sneak up on them (not easy). When sufficiently harassed, the flock will usually decide other food is less dangerous, and quit (for a while). They'll be back, though
We have not succeeded in training bluejays to stay away- and they become very quiet and fly furtively when stealing nuts- if you're not looking for them, you will not see them. We have slowed them down with various techniques, and we no longer mark bushes- for them.
BE AWARE. This is a tough year; the theft can be extensive.