Was that a squeaky toy… or a bird? Could be it was the trademark call of the Brown-headed Nuthatch, a tiny little bird with a brown head moving upside down on the bark of a pine tree.
It’s their habit of wedging a large food item in a crevice and then hacking at it with their strong bills that gave this little bird its name: “nut-hack”.
Little is the key phrase. The brown-headed nuthatch is about the same size as the pygmy nuthatch and the two species are the world’s smallest nuthatches. the total length is 3.5–4.3 inches, wingspan is 6.3–7.1 inches and body mass is 0.35–0.42 ounces. This species sports a brown cap with narrow black eyeline and buff white cheeks, chin, and belly. Its wings are bluish-gray in color. A small white spot is found at the nape of the neck.
Brown-headed Nutties are cavity nesters and will use a bird house if you put one up. Check the recommended dimensions  and make sure the hole is not oversized or these little guys may be booted out by a larger bird.
Atlanta Audubon says: “The Brown-headed Nuthatch is a non-migratory species identified as declining in Georgia by authorities including the Georgia Department of Natural Resources and National Audubon Society.”  AA has a page dedicated to the Brown-headed Nuthatch and some suggestions on how you can help.
Listen for their unmistakable call in your yard and on the Nature Trail.
References and Additional Information
 Wikipedia: Nuthatch and Brown-headed Nuthatch
 Atlanta Audubon: Brown-headed Nuthatch
 Bird House Dimensions
 Cornell – All About Birds: Brown-headed Nuthatch > Sounds