Conserve Wildlife Blog

Posts Tagged ‘reptile’

Mapping Rattlesnake Dens in Northern New Jersey

Friday, May 13th, 2011
PROTECTING WILDLIFE BY MAPPING THEIR HABITAT

By Michael J. Davenport, Marine Species & GIS Programs Manager

A juvenile timber rattlesnake at a den site. © Mike Davenport

Having accurately mapped rare species data is essential for insuring that critical habitat for those species remains protected.  For that reason, I recently accompanied Kris Schantz, a biologist from the NJ Endangered and Nongame Species Program, in documenting two timber rattlesnake den locations in northern New Jersey using a GPS (global positioning system) unit.  Our goals were to see if the rattlesnakes had emerged from hibernation, survey how many were present, and to accurately map their locations in the heavily wooded area less than 30 miles outside New York City.

Using a GPS unit to map a rattlesnake den. © Mike Davenport

Timber rattlesnakes (Crotalus horridus horridus), like other reptiles, are cold-blooded.  In order to survive through the long, cold winter in New Jersey, they hibernate in dens.  Research has shown that rattlesnake dens in the northern part of the state can vary from rocky outcroppings with crevices, ledges or boulders to forest interior dens consisting of a few rocks and a hole in the ground.  In New Jersey’s Pinelands, however, rattlesnake dens are quite different.  Rattlesnake dens in the Pinelands are usually underground crevices near bodies of water, often underneath large tree roots.

Rattlesnakes will almost always use the same den year after year.  In addition, rattlesnake young typically follow the scent trail of their mother in order to find their way to her den their first fall, or may follow any timber rattlesnake to a suitable den.  As a result, a good den site may provide a winter refuge for a number of rattlesnakes of all age classes, as well as other species of snakes.

Since the goal of our mission was to map den locations, we had to make sure we arrived at the den site once it was warm enough for the rattlesnakes to come out of their crevasses to bask but before they had enough warm weather to travel away from the den site.  Timing was crucial.  After a week with some fairly warm days mixed with very cool nights and a few cool days, we ventured out during the last week of April on a day when the air temperature climbed into the lower 80’s.

The first den site we visited required a fairly long hike through a rocky, deciduous forest.  Fortunately, Kris had visited both den sites several years earlier so she had a good idea of where we needed to go.  We were fortunate to find two individuals at the den site, one yellow-phase juvenile and one yellow-phase sub-adult or young adult.  While I GPSed the den site, Kris attempted to determine their sex based on their appearance (the young adult was a female but the juvenile’s sex could not be determined).

GPS units work when there is an unobstructed line of sight to four or more GPS satellites.  With 7-8 satellites being detected by the GPS unit, my task of mapping the site was fairly easy and took little time.  The trees had yet to leaf-out so my GPS unit had a clear signal from above.  We also observed a northern black racer (Coluber constrictor constrictor) at the den site.

The second den site required a much longer and more strenuous hike accompanied by swarms of black flies.  At that location, we observed three rattlesnakes – one black-phase adult (sex undetermined), one yellow-phase adult male, and one yellow-phase sub-adult or young adult (sex undetermined).  GPSing this location took a little more effort though due to the terrain both because it was more difficult to get to the site and once there, the terrain made getting a clear signal on the GPS unit a little more tricky and it took far longer than at the first den.

Out of the five rattlesnakes we observed, only one ever rattled.  Rattlesnakes rely on their camouflage as their first line of defense.  Even when we were close by, they remained motionless.  At no point did any of the snakes approach us or attempt to strike.  The only two individuals which moved at all during our survey, moved away from us into rock crevasses and that was likely due to our prolonged presence staring at them.

Snakes, and venomous snakes in particular, have an undeserved bad reputation.  At no point during our survey did I ever have any fear of being bitten by a rattlesnake.  In all honesty, I was actually far more afraid of being bitten by a tick instead (I only found about four or five on me during the entire day).

For more information on timber rattlesnakes, visit Conserve Wildlife Foundation’s on-line field guide to New Jersey’s rare species at:  http://www.conservewildlifenj.org/species/fieldguide/view/Crotalus%20horridus%20horridus/

Are you Aware?

Wednesday, February 2nd, 2011
Protecting Terrapins Through Education and Awareness

By Ben Wurst, Habitat Program Manager

Female Northern Diamondback terrapin by Jonathan Carlucci

Terrapins are ectothermic, or they are cold-blooded, and their activity is regulated by external temperatures in the environment. While they may be dormant at the moment, I’m far from that. I’ve never stopped working to protect terrapins from the end of last year’s nesting season. While it’s almost impossible to prevent every terrapin from being hit-by-car, it’s more important to highlight the need for protection and for people to become more aware of terrapins when driving.

Here are a few things I’m working on to help terrapins in the Great Bay area this year:
  • I’ve been working on getting some funding to help raise awareness, i.e. more X-ING signs, other signs (like “slow down, terrapin X-ING”) and other educational materials.
  • I developed an educational presentation about terrapins and our work to protect them. I just presented it for the first time a couple weeks ago at the Jacques Cousteau Coastal Educational Center in Tuckerton.
  • I have been in touch with the town engineer for Little Egg Harbor Twp. about lowering the speed limit on Great Bay Blvd. this year. The speed is currently 50mph!! For a road with soft shoulders (and in some areas, saltmarsh or shrubs that are growing onto the road), seven bridges, a lot of human use in summer, terrapins that nest on the edges and enter the roadway, and the fact that it divides a pristine Wildlife Management Area, it is just way too high.
  • I am attending both the environmental commission and town council meeting this month to address my concerns and to ask for their support for our project.
  • I recently met with officers from the Osborne Island Homeowners Association to assist them with protecting terrapins along Radio Rd.
  • I am developing a volunteer project where volunteers will help patrol area roadways to educate the public about terrapins, to help them cross roads safely, and to help document terrapins on roadways.
If you would like to help us protect terrapins in the Great Bay area, we could use your help!

Rare Species Spotlight

Thursday, June 24th, 2010
Eastern box turtle (Terrapene carolina carolina)

By Ben Wurst, Habitat Program Manager

Key Features

Highly domed carapace (upper shell) and a hinged plastron (lower shell). Most terrestrial turtle found in New Jersey.

Identification

Box turtles range in length from only 4″ up to 8.5″. The shell of the box turtle is unique. It’s carapace is high and shaped like a dome. It’s keel, or the ridge along the backbone is weak or very flat. The plastron is hinged and can close very tightly, in front and in rear. This is meant to protect the turtle from predators, especially the neighborhood dog.

Box turtle at a restoration site in Burlington County, NJ. © Ben Wurst

Sexes are slightly similar in appearance. Both have  yellow, orange, olive, or tan on their carapace and plastron that is contrasted by a light or dark black background. Individuals can appear very different in coloration. The male (pictured above) is very vibrantly colored. Younger turtles are more vibrantly colored than older ones. Males have a longer and wider tail than females. Their carapace is often more flattened than females. Males have a more vibrantly colored (orange or red) eyes.  The plastron of males is slightly concave. Females have lighter colored (light brown to light orange) eyes and their plastron is flat. Their carapace is often more domed in shape.

Distribution and habitat

The Eastern or Common box turtle occurs in the eastern United States from central Maine south to southern Georgia and Alabama, west to central Michigan and southern Wisconsin and then south into parts of Illinois, all of Kentucky, Tennessee, and then parts of Mississippi. It can be found in all of the 21 counties in New Jersey.

Range of the Eastern box turtle. Image courtesy Davidson College Herpetology Lab.

Box turtles inhabit open woodlands and meadows. They are often seen in neighborhood backyards in rural and suburban areas. They are usually not far from streams or ponds, however, during rainy weather they may roam farther from water. They are the most terrestrial turtle found in New Jersey. They like water, but are not adapted for swimming in water.

Studies have shown that box turtles have very small home ranges. Researchers found that their territories are around 250 square yards or less. If box turtles are removed from their territories and placed in an unfamiliar area, then they may die while trying to find their way back home. It is very important to not take a box turtle from its habitat and relocate it. If you find an injured one and do transport it to a state certified rehabilitator; record the animals location and make sure to inform the rehabilitator so it can be re-released where it was found.

Diet

Box turtles are omnivores. Changes in food preference occur during different seasons and life stages. Young turtles eat more insects, while adults eat more plant matter. Young turtles eat earthworms, snails, insect larvae, and some vegetative matter. Adults eat large quantities of fungi and particularly like berries and fruits from trees and shrubs.

Life Cycle

Box turtles, like other reptiles are cold-blooded and in the northern parts of their range hibernate from late October or November until April. During hibernation they burrow into loose soil, vegetative debris, and/or loose sand, and sometimes in the mud of stream bottoms. They dig burrows with their front legs, instead of their back legs (which are used to dig holes for laying eggs). Some hibernate at depths up to two feet deep. They can arise during warm spells.

The plastron of the box turtle helps indicate the sex of the individual. © Ben Wurst

Individuals become reproductive at 4 to 5 years in age. They can live to be older than 20 years in age. Mating begins shortly after individuals emerge from hibernation. During courtship, males chase or follow females to mate. Males often bite the edges of the females carapace, head, and neck. The male mounts the female (males have the concave plastron that helps during copulation) and hooks his back legs under the back edge of the females shell. During copulation the males body becomes upright and reproduction occurs. There has been evidence that females can remain fertile for two or three years after mating.

Eggs are laid in June and July. Nesting usually occurs in the late afternoon. Females deposit eggs in a hole that she digs in loose or sandy soil and sometimes in lawns. The cavity is around 3 inches deep, or about as long as the back legs of the adult female turtle. They lay between 2 to 7 eggs.  Most hatching occurs in September or average incubation is around 87 to 89 days. Young either remain in the nest after hatching, emerge and go directly into hibernation, or emerge and explore for a few days to weeks, then hibernate. They do not require food during their first summer or fall before going into hibernation.

Current Status, Threats, and Conservation

Box turtles are fairly common throughout their range; however, they’re population is declining in New Jersey. Habitat destruction and fragmentation isolate individuals from finding mates and food. This causes local populations to decline in numbers or become extirpated from an area. Their slow reproductive rate does not allow for a fast recovery if a local population losses several individuals in a given amount of time.

Be aware for box turtles while driving!

Another threat to box turtles is the illegal collection for use as pets. They are highly sought for their use in the illegal pet trade (one of the world’s most profitable markets). Many people collect box turtles to breed in captivity for use as pets. Another conservation concern is the impact of high mortality rates from impacts with motor vehicles. Many roads transect suitable habitat for box turtles and many turtles that enter roadways die each year.

These threats have exacerbated their decline and the fact that the NJ Division of Fish and Wildlife, Endangered and Nongame Species Program have listed them as a Species of Special Concern. This listing will mostly importantly help garner protection through enhanced habitat protection of suitable or critical habitat for box turtles.

How to help

The Endangered and Nongame Species Program would like for individuals to report their sightings of box turtles. Record the date, time, location, and condition of the animal and submit the information by submitting a Sighting Report Form. The information will be entered into the state’s natural heritage program, commonly referred to as Biotics. Biologists map the sighting and the resulting maps “allow state, county, municipal, and private agencies to identify important wildlife habitats and protect them in a variety of ways. This information is used to regulate land-use within the state and assists in preserving endangered and threatened species habitat remaining in New Jersey.”

References

Carr, Archie. 1952. Handbook of Turtles, The Turtles of the United States, Canada, and Baja California. Cornell University Press.

Schwartz, Vicki and Dave Golden. 2002. Field Guide to Reptiles and Amphibians of New Jersey. NJ Division of Fish and Wildlife. Available in our online store!

The Davidson College – Herpetology Laboratory. Eastern box turtle information.