When I went moose hunting in Alberta last year I had downloaded the Canadian Non-resident Firearms Declaration sheet and filled it out, but it is a legal size paper and my printer only does standard size, and Canadian Customs didn't like my 2 pages, so I had to fill out a new one there. They also asked to see my US Customs Form 4457, and my hunting contract with my Canadian Outfitter. They also came out to my car to inspect my rifle and verify it's serial number. And I paid the $25 Firearms Conformation Fee.
Coming home, there was a very long wait at US Customs and when I finally got an Agent, he only wanted to see my Canadian hunting license and had me fill out a form for the meat. He didn't want to look at the horns, cape, or meat. And they didn't ask to see my Form 4457.
On a previous Canadian hunt, US Customs inspected the skulls of my Caribou and Musk ox, and gave me a ration of $hit that my Muck ox skull hadn't been boiled. They finally let me through though.
Remembering my Musk ox hassle, I had asked my Moose Outfitter about boiling my moose skull, and he said just to stop at a car wash and pressure wash the skull, which I did, then the US Customs Agent didn't ask to see it. Better safe than sorry though.
I saw wolf tracks on my moose hunt, but didn't see any wolves.