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Eastern Garter Snakes Giving Birth

Seventy percent of the world’s snakes lay eggs and only about thirty percent give birth to live young.  Eastern Garter Snakes (Thamnophis sirtalis sirtalis) are among the latter, giving birth in August to between two and thirty-one offspring (averaging 23).  Carrying and incubating developing embryos within their body is more common for northern snakes and there is good reason for this.  Whereas eggs are subject to whatever temperature fluctuations occur where they were laid, a snake that carries her young to term within her is able to move to warm areas that are ideal incubation temperatures. This causes less stress for the developing embryos and also results in a greater number of viable young.

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12 responses

  1. This is so cool – eggs developing and hatching inside the mother’s body. I read that the female can store sperm, and fertilize her eggs whenever she is ready. Then the eggs develop inside her. No placentas. I found this great video of a garter snake birth. The newborn snake is still inside the egg sac when it is born, then breaks free.

    August 26, 2020 at 8:41 am

    • Oh my goodness!! And then… starts breathing, I guess. And then goes out and figures out how to survive! What a remarkable video! Thanks for this!

      August 26, 2020 at 8:22 pm

    • That’s darn fascinating! Reddit another excellent site, very very interesting stuff!

      August 27, 2020 at 3:29 am

    • Wow, Kathie! Your video is fantastic!!! Thank you for sharing!!!

      August 27, 2020 at 10:11 am

  2. Dianne Rochford

    Hi Mary,

    I know you have moved…….I’d like to write you a note especially in regard to your recent post about ‘Myrmecochory’, and enclose a small check for your beloved work.

    Please send me your snail mail address.

    :-), Dianne >

    August 26, 2020 at 8:59 am

    • Hi Dianne,
      I have moved and I miss Hartland so much! My new address is 505 Wake Robin Drive, Shelburne, VT 05482. I would love to hear from you!

      August 27, 2020 at 10:12 am

  3. Alice

    Always glad to see snakes in our yard. Very recently about an 8″ garter & before that a very large one behind our garage. And I counted at least 13 painted turtle noses in the drying up pond, near our house with my grand daughter, yesterday & one on a log & a frog & lots of dragonflies.

    August 26, 2020 at 9:05 am

    • Nice story, nice you enjoy your yard of wildlife!

      August 27, 2020 at 3:27 am

    • Outstanding, Alice! Your lucky granddaughter!

      August 27, 2020 at 10:13 am

  4. We have lots of Garter Snakes (loved them since I was a child and was told they didn’t bite) cats find them, they are smart they fake death and get to go free! 🙂 ❤

    August 27, 2020 at 3:26 am

    • I know hog-nose snakes feign death, but wasn’t aware that garter snakes did!

      August 27, 2020 at 10:14 am

  5. Karen Watson

    So if some snakes lay eggs are they still reptiles, or does this classify them as mammals?

    August 27, 2020 at 6:54 pm

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