I had a family of garter snakes living inside my siding exactly same situation as you had when i put the deck on i removed siding to attach the ledger and half a dozen snakes came out of the lower trim piece just like you describe.
Garter snake in house siding.
Through gaps between brick and siding osborne also warns that snakes can get inside by slipping between bricks if mortar is missing and also between bricks and siding on the exterior of your home.
That one does not look like any of those so most unlikely it is poisonous.
Visually inspect your siding for openings through which the snakes can find access.
Lifting up the loose edges allows for some of the snakes to drop out.
Yards and gardens easily become their cozy homes so they can feed themselves on earthworms tadpoles insects mice lizards and other reptiles found in this area.
The most distinguishable feature of garter snake is a light shaded stripe running along its back.
These may be located at.
The snakes climb up into the openings and use the space behind the siding.
Gaps between siding and stone veneers brick or any similar material should be repaired to prevent moisture damage and stop snakes from gaining entry.
Garter snakes living in vinyl siding removal.
They prefer to live in a warm and damp environment.
Due to their combined smell a large group of garter snakes in or under your home can make your residence uninhabitable.