Im sure that something like that was the reason. There are other old sayings like that for a number of things and they have different reasons behind each. Two others that come to mind just related to the “never in a month without an R” are harvesting venison and horseradish.
“Two others that come to mind just related to the never in a month without an R are harvesting venison and horseradish.”
Rabbits and squirrels as well due to tularemia.
Nasty illness commonly known as rabbit fever or deer fly fever. Commonly attacks the skin, eyes, lymph nodes and lungs.
Even with prompt treatment the illness can last several months.