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Bob Mason  

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Garter Snake biology and behavior  

NPR/NGS Radio Expeditions
4 May 1997

    Geography
  • Canada
    Manitoba
    Locality
  • 6.0 km N of Narcisse; Narcisse Wildlife Management Area; Snake Dens
    Latitude/Longitude
  • 50.735   -97.53222
    Habitats
  • Grassland
    Channels
  • Stereo
    Sampling Rate
  • 48kHz
    Bit Depth
  • 16-bit
    Recorders
    Microphones
    Accessories
    Equipment Note
  • Stereo=1; Split track; Neumann KMR 81; Shure SM85

NPRINGS RADIO EXPEDITIONS SNAKES LOG -
Manitoba, Canada
May 3,1997
DAT#1
{split trk -left KMR 81 (Bob Mason), right, (Alex)}
Bob Mason = BM
02:41-3:07 BM: "Indiana Jones has nothing over the truth here. This is the most snakes you'll see anywhere in the world."...There are probably about 8-10,000 garter snakes here. They're all mating, they're not eating, drinking. They're just interested in reproduction.
03:19 -4:10 AC: "There's a ball of these snakes right there.... BM: "You're seeing the focus of the whole point of our being here, and the snakes...and that is what we call a mating ball.....when the males all ball up around a female.... and if you look for the large animal at the center of the ball, that's the female, and you can see the males courting her. They're rubbing their chin up along her back, and they all stop right behind her head... and they're picking up that pheromone, that odor cue that the females produce, and that's what attracts the males to her."

06:41 -6:51 BM: Virtually all of them are males. There are only about a dozen females on the surface. The effective sex ratio here in the dens is about 1000-1.

07:09 -7:32 BM: The sound that you hear .... is the sound of the snakes rubbing their skin one against the other, and there are just so many of them here, that they make that ethereal sound. It's a pretty unique sound. I don't think you'll hear that anywhere else in your travels."
16:09 -17:23BM: So here's a female, there's a bunch of males wrapped around her, and you'll see that one male is attached at the back end here. That's the mating act itself. So... here we are holding this copulating pair, and I can assure you they're not thrashing about or struggling.....Male snakes have hemi penis, actually have two, a right and a left.. ..so they're coupled
up....they seem to be quite content.
AC: Males come out first, more description and FX of scene, larger females a few at a time

27:00-27:30 BM: We really don't know what makes a successful male. What are the qualities in the male that the female chooses to mate with. Surely, she has as great a selection as any in the animal kingdom. She has literally hundreds of suitors to pick from. What is it that makes than male so special that she chose that male to mate with. That's an active question we're looking at right now. 46:30-46:55 Each year we can look at several thousand mating pairs, and it's not the largest snake, it's not the longest snake, it's not the oldest snake.... we just don't know what makes a male a successful male. It's a real mystery.

AC: [pick up female and describe her]
54:11 -54:51 BM: The females will mate here in May, and store the sperm for about 6 weeks, and in the meantime, they've left the den and gone out in the feeding grounds -and if it's a good year with lots of food, they'll eat, they'll use that stored sperm to fertilize their eggs. They'll give birth to live young in the end of August. If it's a bad year, they'll just continue to store that sperm through the whole course of the year. And in fact, these garter snakes are somewhat remarkable in that they can store sperm for up to 7 years....after those years, the sperm are still viable and can still fertilize eggs."

1:09:05 -1:11:03 BM: They've been underground for 8 months of the year, haven't eaten a thing. There's no food in the den...and yet the only thing on their mind is to mate.........AC: Do you see them starve to death. BM: No, we've done... some long term mark recapture studies where we can weigh and measure when go into hibernation in the fall, and then we capture them when they first emerge in the spring, and what we've noticed is both the males and females are losing only 10 % of their weight. ... so unlike other hibernating animals like bears....they lose maybe 40%... these snakes in good shape.

1:12:46 -1:13:39 AC: What good is all this research? BM: There's 2 answers. One is that this is really a remarkable natural phenomena. It's a wonder of the
natural world. You'll never see this many snakes anywhere else in the world. How do these snakes survive here. They're the most northerly living reptile in all of the western hemisphere, maybe in the whole world. How do they make it here......Questions of reproduction. The females can store sperm for years, and yet we have problems storing sperm in liquid nitrogen even over the course of several months.

1:17:53-1:18:58 AC: Tell me what happens when they hibernate. BM: Hibernation in these snakes is another very interesting question. These snakes go underground and they hibernate for up to 8 months of the year, and while they're hibernating they actually lose very little of their bodyweight. Now if we were to go into hibernation or something like a bear, were to hibernate, you lose a lot of body mass. A bear might lose up to 40% of its body mass..... This is an important question ....the idea of space travel where we have to go.....will take up many weeks, months of time. How is it that humans are going to be able to survive under those conditions? Well, here, the snakes are doing it for up to 8 months, and they don't seem to be phased in the slightest.

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