Sounds like the neighbor from hell... Around here we have a lot of dairy farms and the farmers tend to leave the snakes alone because of the rodent situation.
I have never seen garter snakes hanging out in a tree, but we do have a rather large one that climbs the barn wall (vintage 1880's fieldstone/morter about 18 inches thick..) and uses the rocks as a ledge to sun himself.
The only snakes that get attention are the copperheads. Have never found any on the property, so thus far I have not had to deal with them.
A developing problem here is that a lot of the old farms are being turned into developments of McMansions populated by cityfolk and they're skert of anything that lives... But they won't neuter their cats, so they take the offspring down the road to where there are still farms and toss them. So along with the garter snakes, corn snakes, red tailed hawks, somekindofnoisyowl (only hear him at night, haven't been able to light him up to ID..) that sounds like a Great Horned, and the occasional Snowy Owl (had one swoop down on one of the outdoor cats while we were watching out the back door.. don't know why it decided to call off the attack, it sure looked big enough to have carried the cat off..) (the cat is now indoors ;-) we have semi-feral cats which do rodent control but also provide entertainment for the pack of coyotes that cycles through about every two-three weeks..
The willow is nearby and in a very marshy part of the yard and during the summer heat, they'd drape themselves festively over the lower branches to escape the unbearable heat.
They weren't bothering anybody but one day he was weed-whacking the property line before we have the solid wood fence and spied them.
He “meant well”, for what that's worth.
We have all that stuff too and eagles.
A couple years ago one of them spiraled right down at my Portuguese Podengo Medio while I wasn't but a short distance from her.
It didn't give a flip that I and several other large dogs were right there..it wanted to eat her.
I lunged for her and that scared her so bad that she flattened out on the ground just as the thing swooped over us both, brushing my head with its wings.
I grabbed her up and ran for the door with the other dogs following.
The infernal chicken hawks have just about wiped out all the small mammals locally and now I see them perched along the highway on the powerlines starving, hoping for some roadkill.
“Protecting” the red tails sure worked out real well for them.
[some fruit loop Democrat “cat lady” who lived in the city near here 'never saw any’ and talked Glendenning into believing they were ‘endangered’...yeah, right]
I often wonder what she'd think if she saw them picking off her precious stray cats in the spring when their chicks hatch.
We have a lot of strange and ignorant people here.
There is a colony of feral cats in the arroyo not too far to the west of here, and one of the neighbors takes feed to them. They seem to be one of the main food sources for a couple of local coyotes, though stray dogs on this property have been seen to become fodder for the mom coyote.
The feral kittens don’t last to long unless they are wise to the teachings of the adults in the colony.