Fleas & Ticks on Chipmunks - Is it common during the warmer months?

As I said in a previous post, I’ve shot north of 100 of these critters and they’ve always been clean, no fleas or ticks. This is the first time that I’ve seen a chipmunk covered with fleas and carrying a tick. I’ve never shot them during the spring or summer only in the fall. Is it common for chipmunks to carry fleas and ticks prior to the cold weather in the fall? (12yds, 831fps, 19ft/lbs. at target)
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Yea, I used to leave the grey squirrels alone, here on my oak tree covered 1 acre. They bark at and tease my dogs, that occasionally catch one. Then I began to notice all the scratching they do, while up in the trees, and figured they had something on them. So, the same time, I got interested in PCP air guns. 9 guns, 3 compressors, 4 air tanks later, can't find a squirrel anywhere! :) ;) :)