UB, I think Canines have regular feeding grounds. Places where they know they can fill their belly. As the seasons change, methinks the feeding grounds change. And during extreme conditions, canines find food or die. It's tough out there and a caller can take advanage from time to time.
Remember the winter of '95-'96? Snow, snow and more SNOW! Roofs were caving in, folks were shovle'n roofs off.
I was still run'n a small trapline and call'n during these extreme conditions.
Here's an example how things are related...
-A farmer didn't get a small corn field in before the snow piled up, that season
-Muskrats gathered on this section of creek to eat this corn during harsh, deep snow conditions
-Fox migrated/concentrated to this creek bottom/corn field to catch feeding Muskrat
-Hern focused on this hot spot to kill many Fox
I saw in the snow....where the Muskrats tunnel (lots of tunnels) thru the snow to get to the corn. I saw where Fox sat and waited (like a cat) for Muskrat to come by, then pounce on them
At times, as fur killers, we wonder where did all the Coyotes go? Where the heck is the Fox? Other times it seems we are loaded with Fox! What the heck?
A bit of experience, scouting, time of year may reveal answers to the questions...'Why'...canines may have moved to different food source.
In season scouting will help one to keep up with the changes.