They don't hang out too long when it's hot out. The Eastern Gray squirrel prefers the cooler weather. You will have a lot more chances of seeing them and getting a shot off very early in the morning. If you can get out where you spotted those dens around 6-6:30am and settle down somewhere you will see them and hear them and the nuts falling all around you. I wouldn't even use the call. That can agitate them and alert them and they tend to hang out very close to their den or hole in the tree when you make sounds of a hawk or a squirrel in distress. That is from my personal experience away. I see those as "threatening sounds". I use a call only as the very last resort when I can't locate them. Get out there early and keep your eyes at the tree tops (higher than mid-way up) and on the ground, and you will see them feeding or running on the ground to get from one tree to another. They all come out early between 6:30am and 10am. Some of them are so hungry and busy feeding, that don't even pay attention to you, even though they know you are there, especially when they are 50ft up or 30yds out. They feel safe when they are farther out, but only until you miss your first or 2nd shot It should be getting cooler in the next few days with the Hurricane coming and it's supposed to be in the low 70's most of next week, so you will have a lot more success then, even in the evening. Don't go out too late. They 'll be there between 4 and 6pm when the temps drop in a couple of days. What gun are you using anyway? Looking forward to your posts!
One more thing, what are you wearing? I've found that squirrels seem to have a keener eyesight than almost any other animals except maybe a turkey. While deer hunting with a bow, I've noticed that squirrels can sometimes pick me out when other animals, especially deer don't seem to see me. I think I read somewhere that deer are colorblind and so the orange thing works for them but squirrels are not. I try to camo up for squirrel hunting just like I would when bowhunting for deer. Also, I try to wear a "boonie" hat with a floppy brim because I believe the squirrel sometimes spots my shining face when looking up! Otherwise, hunt the food and the squirrels will come to you. It may be too early in your parts for them to start ganging up but they will sooner or later. When they do, being in the right place with the right (quiet) airgun will get you quite a few.blessings on your hunt, brojoe
Oh and I am using a new Benjamin Trail NP .22 cal that I just picked up