Question I SHOULD know the answer to...

[ironglow]

 
     Being an old, lifelong hunter here in NY, I should know the answer but (redfaced) don't..

   So here goes:

  Those squirrel nests we see so prominently in trees...Are they only made by red squirrels ?
 
  If so, then are the grays & blacks not likely to be there due to the reds aggressive behavior ?

  Enlighten this old man a bit, since I'm considering a squirrel dog...

[mcwoodduck]

Where I hunt in NC we do not have Red squirrels only the gray and they make the nests too.  I have also seen an Opossum come out of one of the nests as well.  Your best bet is to find a good source of food, a good low folding chair and a good 22 rifle and sit down at the base of a tree.  I find a good 15 min nap works great.  The squirrels will start to go about their day and will bark at you and move their tails to let you know where they are.
I like the gobbler lounger from Cabela's as my chair.  Comfortable easy to walk with and gets your knees high to use as a rest for longer shots and most important gets your butt of the cold wet ground.
As for the rifle we could talk all day about what is the Ideal squirrel rifle and bullet.  And yes that rifle can be of the short variety.  I have taken quite a few bushy tails with my Buck Mark handgun.
Early in the season I like open sights and late I like to use a scope for longer shots as the leaves fall off the trees with 40 grain round nose standard 22 LR ammo.  I think the standard velocity with the round nose does not tear up the critter as much as the faster or hollow points do and not all of my shots can be head shots.

[Mikey]

Ironglow:  the nests you see are most likely made by the Gray Squirrel.  The Red Squirrel or Fox Squirrel is also refered to as the Ground Squirrel and lives in ground nests and sometimes trees.  They will occupy Gray Squirrel nests when the fleas drive the Squirrels out, especially from inside trees.

The Gray Squirrel is the most aggressive.  The Red Squirrel seems to be the more aggressive but isn't.  Sometimes Grays will kill the Reds.  The Black Squirrel is a Canadsian transplant, as I understand, and are not as aggressive as the Gray Squirrel - this I have been told but I have seen a fair number of Black Squirrels in the neu yawk city area and particularly in the Bronx and only on the fenced grounds of the Bronx Psychiatric Center of all places.  They must really like the nuts............................

I thought I had a pair of Black Squirrels in my yard a couple of years ago but couldn't really tell if they were black in color or just a very dark gray.  Unfortunately, a Red Fox took them both and I wasn't able to verify what I saw.

I saw your other post about a squirrel dog and the types of breeds you are considering.  I do not know anything about those breeds and cannot advise you there but if I was looking for a smaller dog - less than 35 lbs, smooth coat and a good house dog I would be tempted to check the local shelter or rescue groups for Poodles.  The Standard Poodle will go to 50 - 95 lbs (depending on breed line and gender) and although large, they prefer laps and couchs if given the chance.  The next size down goes to about 30 - 35 lbs and are great companions and do not shed (they have hair, not fur).  And I have never seen a Poodle, regardless of the size, that won't tear right after a squirrel or any other furry little critter if given the chance.  I think that no matter the breed you will have to train them to the gun and to the sound of gunfire although having a tasty Squirrel they can savage after you knock it out of the tree might help..........HTH.  Mikey.

[.357 shooter]

Ironglow:

      The nests your seeing is most likely Grays. I hunt a piece of state land that was  great for grays but the red squirrels took over. They tend to live in the rock walls in this area or the pole pines and travel to the many oak groves in the area. They have exploded in numbers so much that they pushed the grays out. But during the winter the reds are fun to hunt for pest control to try and knock down the numbers, to help bring back the grays. So far I have shot a ton but am not gaining.