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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