Where Have All of the Squirrels Gone

It feels as if I didn't pay enough attention. I last saw a squirrel in my yard -- a small forest -- perhaps one month ago. Incidentally, around the same time that people began spraying their yards again. There are no local squirrels in my yard even though a woods is close, there is shelter and much habitat provided by a huge several huge oaks, a beech, a dawn sequoia, plum trees, flowering pear , a towering weeping cherry, and much sassafras and other trees.
My tulips are gorgeous this year because no one is eating them. It is so distressing not to see squirrels anywhere when I walk my dog in the 2 mile circle around the neighborhood. I miss their chattering, clucking and chucking at me -- like a teenage sucking his teeth. I miss their scratchy noise as they chase each other around a tree's bark, and of course, I miss their acrobatics, jumping from limb to limb. This disappearance began over winter as fewer and fewer seem to bother the suet and the black oil sunflower seeds. I don't understand what happened to them. I am sad. Image from last year, 2012.