Pair of Garter Snakes under Patio - Ask Extension
Hi, we have a pair of garter snakes living in a sprinkler box next to our back patio. I noticed the other day that they have a hole out of the bottom ...
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Pair of Garter Snakes under Patio #874969
Asked June 27, 2024, 1:16 PM EDT
Hi, we have a pair of garter snakes living in a sprinkler box next to our back patio. I noticed the other day that they have a hole out of the bottom of the box that they go into, like there is a cavern under the patio maybe. We only had 1 snake there last year and my garden was more beautiful than ever, so I know how beneficial they are for eating bugs and such. Now that there are two, I'm a little concerned they're a mating pair as they have differently styled tails (one long and narrow, one short and fat). I've heard they can have many, many babies, which is the concern as I'm worried about how many babies there might be crawling all over my yard and patio. I don't mind a couple bigger ones I can see and watch for as I'm working around the yard (they tend to stay fairly close to the sprinkler box/garden area), but I'm a little squeamish about the possibility of a whole tribe slithering around.
Looking for some advice on what I should/could do so it doesn't turn into an infestation.
Thank you.
Lane County Oregon
Expert Response
You're correct that garter snakes (and other snake species) can be a huge benefit to the home gardener. The description of tails makes me wonder whether you have a pair or whether you possibly have individuals of >1 species taking advantage of the safe, moist (?) environment so near their hunting ground (your garden). Do you happen to have clear photos of each animal that you could upload here?
As for an infestation: In some very rare cases, somebody's house might be sited on or near an over-wintering hibernaculum in which dozens of snakes will gather to shelter over the winter - but once breeding season comes with the warming of spring, they all disperse back to their own territories near and far. It sounds more like you have two snakes - Snakes generally do not "pair up" beyond meeting, breeding, and then going their own ways. If one or both happen to be pregnant, you're right in that you could have a brief (seasonal) increase in snake abundance for a short time, but then the juveniles will disperse to seek their own ranges and territories. Dispersal helps prevent competition for food among relatives and also prevents in-breeding.
As for an infestation: In some very rare cases, somebody's house might be sited on or near an over-wintering hibernaculum in which dozens of snakes will gather to shelter over the winter - but once breeding season comes with the warming of spring, they all disperse back to their own territories near and far. It sounds more like you have two snakes - Snakes generally do not "pair up" beyond meeting, breeding, and then going their own ways. If one or both happen to be pregnant, you're right in that you could have a brief (seasonal) increase in snake abundance for a short time, but then the juveniles will disperse to seek their own ranges and territories. Dispersal helps prevent competition for food among relatives and also prevents in-breeding.
Dr. Sanchez,
I only have a picture of the bigger/fatter one. I hadn't thought of them being different species of garters. The one I don't have a photo for is much slimmer and a bit shorter. The bigger one I have the picture of has a much brighter yellow stripe - the yellow stripe on the other one is much more muted. I found their last sheds within days of each other so maybe their colors are generally slightly different.
If both/either are expecting, about when could we expect to see babies?
The stripe colors on garters is quite variable - some are so faint that they appear to not have striping. I am not a herpetologist, so I'll do my best here, and if you need more information than I can help with, we might have you contact Dr. Bob Mason (also at OSU but not Extension) because he IS a herpetologist.
The snakes could appear "fat" after having a large meal. The difference in tail end shape probably means one of them lost part of its tail in an injury - whether something tried to eat it, or as I learned via this very informative listing https://animaldiversity.org/accounts/Thamnophis_sirtalis/#:~:text=Garter%20snakes%20are%20low%2Dlevel,amphibians%20with%20strong%20chemical%20defenses it could have gotten a nematode that results in tail-loss by eating a larval amphibian infected with that particular nematode.
I don't think an "infestation" is possible. The only way you would have a large influx of snakes is if you happened to have an over-winter hibernaculum on your property - very unlikely - You would have noticed a huge number of snakes out-bound from it at the end of winter :)
If either of your snakes is pregnant, she'll give birth to live young at the end of summer. She doesn't provide any post-birth care or feeding, so the young will slither off to find their own home ranges and hunting grounds after a few days to week.
The snakes could appear "fat" after having a large meal. The difference in tail end shape probably means one of them lost part of its tail in an injury - whether something tried to eat it, or as I learned via this very informative listing https://animaldiversity.org/accounts/Thamnophis_sirtalis/#:~:text=Garter%20snakes%20are%20low%2Dlevel,amphibians%20with%20strong%20chemical%20defenses it could have gotten a nematode that results in tail-loss by eating a larval amphibian infected with that particular nematode.
I don't think an "infestation" is possible. The only way you would have a large influx of snakes is if you happened to have an over-winter hibernaculum on your property - very unlikely - You would have noticed a huge number of snakes out-bound from it at the end of winter :)
If either of your snakes is pregnant, she'll give birth to live young at the end of summer. She doesn't provide any post-birth care or feeding, so the young will slither off to find their own home ranges and hunting grounds after a few days to week.
