Before we get into this week's topic, check out Chris and Dave's recent appearance on NHPR's Outside/In. They joined host Sam Evans-Brown for a special edition of "Ask Sam".
There are few sounds in nature that command your attention as effectively as the rattle of a rattlesnake. And though these snakes are not aggressive, that sound does elicit a hard-wired, innate fear response. Roughly translating to “Watch Your Step, Mister!” the rattle is an alarm designed to stop trouble before it starts.
We often think of rattlesnake habitat as a mesa, or desert, or at least somewhere west of here. But though at Something Wild we try to focus on the flora and fauna of New Hampshire, we claim the rattlesnake as fair game. The Eastern Timber Rattlesnakes has historically been a New Hampshire species, in fact, they were here before we even called this place New Hampshire! But now there are only as few as two dozen individual rattlesnakes left in the entire state, and those are in managed populations.
While the eastern timber isn’t an endangered species (the International Union for the Conservation of Nature designates it as a species of “least concern”) it is very nearly extirpated within New England. In Maine and Rhode Island they are no longer extant. They were quite common during the time of the first European settlements. Colonists encountered them frequently, seeing them as fearsome creatures, a fact memorialized by the appearance of a timber rattlesnake on the yellow Gadsden flag, that became a rallying symbol during the American Revolution. But their respect for the snake was begrudging at best, as they were also intent on killing the snakes.
So our perception of rattlesnakes has mostly been based on fear over the last few centuries. But the thing is, Eastern Timber Rattlesnakes are not a danger to us - we’re the danger to them. They feed on small forest: shrews, mice, chipmunks and ground-nesting songbirds, which means large lumbering humans not on the menu. As with so many of the predators we’ve examined at Something Wild, the timber rattlesnake is not as aggressive as Indiana Jones would have you believe, only striking when threatened.
Or when hunting. And they have some serious skills. Timber rattlesnakes do not stalk their prey, they’re still-hunters, lying in wait for a mouse to go scurrying by. Their camouflage helps them blend into the background making the coiled rattler look like a bunch of oak leaves. And they have a number of sophisticated biological adaptations. They can see motion, but they can also follow pheromone trails. That’s what all the tongue flicking is about – they’re smelling dinner.
Additionally they’re “pit vipers,” a class of snakes with specialized pits below their eyes sensitive to infra-red and heat-signatures. All these adaptations are designed to help snag chipmunks or mice. But, if you’re not a tasty, small rodent, rattlesnakes are pretty chill. They try to mind their own business.
It seems surprising that a cold-blooded reptile, reliant upon the temperature of the air around them for so much, would find a home in New Hampshire. Their home for much of the year – October to April – is underground, below the frost line, in their hibernaculum. An ideal rattlesnake hibernaculum is a dry place with a steady temperature. It is less likely to be an open cave or burrow, as it is to be a narrow crack or fissure in bedrock layers located near open, sunny south-facing ledges. It’s the warm summer months when they’re most active. Though the females stay close to their ledges, the males travel further afield to hunt.
Unfortunately one of the best places to find food and warmth is near roads. The ribbons of black pavement that soak up the sun all day are an all too tempting place for these black snakes to warm up and blend in for some still-hunting. As they blend in it’s hard for drivers to spot them, too.
Meanwhile, back at the ledge, females are minding the young. Contrary to the ole “envelope full of rattlesnake eggs” gag, and unlike most reptiles, the eastern timber rattlesnake is viviparous, giving birth to live young. But another factor in their population decline in New Hampshire is that they don’t breed every year. They only breed when there is an abundance of prey, sometimes as infrequently as every 4-5 years.
If you have questions about either common or rare species of wildlife in your neighborhood, let us know! SomethingWild-at-nhpr-dot-org.