Q on Sistrurus m. b. natural history

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simus343
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Q on Sistrurus m. b. natural history

Post by simus343 » November 25th, 2015, 7:07 pm

I was just reading some stuff on various amphibian and reptile web pages about pygmy rattlesnakes and a question arose about natural history.

In January of this year a friend of mine got some footage of wild dusky pygmy rattlesnakes mating in one of our Gopher Tortoise relocation pens at work. Then, in August, we had a huge boom of neonates in multiple of our pens. All the neonates were the same size give or take a few millimeters perhaps.

Do they reproduce multiple times a year, once a year at a random time, or just have an unusually long gestation period?

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walk-about
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Re: Q on Sistrurus m. b. natural history

Post by walk-about » November 25th, 2015, 7:43 pm

Please don't quote me on this, but I am fairly certain a healthy, adult female Sistrurus presents her live-born offspring once annually. This is also true of Copperheads and Cottonmouths, which are distantly related to the Pygmy Rattlesnake. Stetson University (FL) would probably have some data regarding this topic, as they were for many years at least, the school leading the way in research of this North American species.

Dave

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Bryan Hamilton
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Re: Q on Sistrurus m. b. natural history

Post by Bryan Hamilton » November 27th, 2015, 7:59 am

Walk about is right, Sisturus milarius (at least in Florida) reproduces annually. Most temperate female rattlesnakes are constrained by the active season and their physiology to reproduce biennially. Even in tropical Mexixo, annual reproduction is the norm. I doubt rattlesnakes in Florida are capable of reproducing multiple times in a year.

Its also not random, parturition occurs mainly in August. You may have been seeing multiple litters in the pens. Mean clutch size is 6.

Good paper on your species:

https://www.researchgate.net/profile/Te ... e6c182.pdf

This paper summarizes reproduction in all amniotes. Its not exhaustive but it is a good starting point:

http://www.esajournals.org/doi/abs/10.1890/15-0846R.1

simus343
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Re: Q on Sistrurus m. b. natural history

Post by simus343 » November 27th, 2015, 3:56 pm

Okay thanks. The paper on Sistrurus miliarius barbouri answered my question. They were seen mating in January. The paper says late fall, but a warm day (lower 70s) in January is only a few months later, so maybe there is a seasonal difference based on region and local ecology as the introduction of the paper suggestion behavioral tendencies based on basking sites and prey abundance. So apparently, the females retain the male's' sperm from copulation for about 1/2 to 3/4 of a year. Question answered - with room for possible research based on distribution and regional ecology.

Thanks guys!

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Stohlgren
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Re: Q on Sistrurus m. b. natural history

Post by Stohlgren » November 28th, 2015, 8:05 am

In the southeast, most rattlesnakes mate in the fall and retain sperm until they ovulate in the spring (when the eggs are actually fertilized). So while most mating activity occurs in the fall, it can happen anytime up until ovulation. They can actually retain sperm for years if they do not have enough fat stored up to reproduce. Females are not reproducing multiple time a year, or even every year, but likely skip a year or two.

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Bryan Hamilton
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Re: Q on Sistrurus m. b. natural history

Post by Bryan Hamilton » November 28th, 2015, 8:10 am

Stohlgren wrote:In the southeast, most rattlesnakes mate in the fall and retain sperm until they ovulate in the spring (when the eggs are actually fertilized). So while most mating activity occurs in the fall, it can happen anytime up until ovulation. They can actually retain sperm for years if they do not have enough fat stored up to reproduce. Females are not reproducing multiple time a year, or even every year, but likely skip a year or two.
Good summary and pretty much right on. Pygmy rattlers though, reproduce annually in Florida.

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Nshepard
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Re: Q on Sistrurus m. b. natural history

Post by Nshepard » December 3rd, 2015, 10:04 am

In Florida, Pigmy Rattlesnakes may very well reproduce once a year but northern forms are likely two years between reproductive events. As documented in other SE rattlesnakes, the Eastern Diamondback Rattlesnake in SC usually goes 2-3 years between reproductive events - sometimes as long as 6 years. Reproductive events = females giving birth. Males, of course, can, and will try to, mate several times a year.

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