Rattlesnakes emerging from their winter dens across Pennsylvania - Reptilenesia
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Scary photos of timber rattlesnakes, sometimes rhumbas of rattlesnakes, are once again appearing on social media as hikers, anglers and others begin encountering the reptiles as they begin leaving their winter dens across Pennsylvania. While the large number of snakes being sighted and reported likely is a result of the number of mobile devices on the trails and along the waters of the state, the timing of the snakes' emergence is about average from a seasonal perspective. "Timber rattlesnakes exhibit habitat preferences at different times of year," to find sources of heat to maintain their body temperatures and to find food," explained Thomas LaDuke, an associate professor of biology at East Stroudsburg University who has led several research projects into the species in Pennsylvania. He was among the presenters in a recent webinar. The same snakes are regularly found in roughly the same spots at about the same time each year. In Pennsylvania, he said, initial emergence is mid- to late April, earlier in southern counties than in the north. After emerging from their winter den, the snakes will gather at communal basking sites near the den, maybe right at the den. They often are seen basking communally in "big snake piles." They will shed their skin within a month of emerging, often within a week or 2. Communal basking will continue into early summer and then adult males and non-gravid (not pregnant) females move off into the surrounding forest to forage for prey. The adult males usually will move out first. Gravid females, impregnated late the previous summer, will move to a nearby gestating/basking site, which might be the same basking site used by all the snakes when they first emerge. They will remain there throughout the summer, maintaining their body temperatures until giving birth Rocky, south-facing slopes exposed to the sun are important to the reptiles when they need to heat their bodies but ambient temperatures are not high enough to get the job done, including when the rattlers emerge from their dens in the spring, when they are about to return into their winter dens in the fall, when the females are gestating babies in their bodies, when they recently fed and need added heat to aid in digestion, and when they are about to shed their skins. Gravid females will give birth to live babies, averaging about 8 per clutch, in late August or early September. The neonates, each 11-14 inches long at birth, will remain with their mother for 7-10 days, shed their skins for the first time and then disperse. They won't reach maturity for another 5 to 8 years. Chris Urban, nongame, threatened and endangered species coordinator with the Pennsylvania Fish and Boat Commission, said the hunting season for timber rattlesnakes in Pennsylvania runs from the second Saturday in June through the end of July. Each hunter with a required fishing license and a snake-hunting permit may take only one male at least 42 inches long and with at least 21 subcaudal scales, which are the scales on the underside of the tail behind the anal scale, per year. According to Urban, significant declines were noted in the state's timber rattlesnake population in the 1960s and 70s. In the mid-1980s, the commission designated the snakes as a candidate species under consideration for listing as threatened or endangered. Statewide inventory surveys were done in the late 1980s and early 1990s. A limit of one snake per used was imposed in 1993. In 2007, after more population assessment studies, the commission approved the current regulations governing collection of the snake. In 2016 the timber rattlesnake was removed from the candidate list. It is now listed as a species of greatest conservation need in Pennsylvania's Wildlife Action Plan. From early July through early September, a period of peak rattler sightings each year, males are roaming in search of mates, and may travel 5 miles or more from the winter den. Nearly all the snakes return to their winter dens in late September through October, ending most of the social media focus on sightings for the year. They end their year in the same dens they vacated in the spring. Here are some additional facts about the timber rattlesnake that LaDuke shared. The largest recorded timber rattlesnake is 74.5 inches, but anything over 50 inches is considered "quite large." Females generally do not grow much over 40 inches. The rattlesnake is a heavy, wide-bodied snake. While the eastern rat snake is the longest snake native to Pennsylvania and can grow to 100 inches in length, by body mass the timber rattlesnake is the largest in the state. A maximum weight of 5.5 pounds is possible in timber rattlesnakes, any weighing more than 2.5 pounds is considered large. There are 2 color phases, based on the coloring of the snake's head: yellow morph or phase and black morph or phase. Most timber rattlesnakes exhibit some pattern along their bodies, and a completely black one is "relatively uncommon." The tail of most is black. Although a timber rattlesnake occasionally kills and eats a bird or small reptile, the reptile is "a mammal specialist," with the bulk of its diet made up by small mammals. In Pennsylvania, the primary prey species of the snake are the white-footed mouse and eastern chipmunk. The species is an ambush predator, usually laying in wait along a trail used regularly by small mammals. During summer gravid females do not feed, relying on fat stored in their bodies while gestating their babies. In northern Pennsylvania and New York, the process of building up enough fat might often mean a female will give birth only every 3 years. |
