Black Racer Movements and Habitat Use
The Massachusetts State Wildlife Action Plan (SWAP) ranks the black racer as common across the state, but it is listed as a priority species because these snakes are declining in abundance everywhere (Mass Wildlife Action Plan, Chapter 3, p28). Martha’s Vineyard is no exception as many islanders report capturing these snakes for fun as children but have not seen one in over twenty years. While they used to be abundant in the town of Oak Bluffs 50 years ago, we have not had a report of this snake from that town or from Vineyard Haven in the last decade.
All snakes found on the island of Martha’s Vineyard are harmless to people and pets, and they are beneficial to have around your yard as milk snakes and black racers both eat rodents, such as white footed mice, that contribute to tick borne illnesses.
In 2014, we began a community outreach effort to locate black racer populations on the island in order to capture a few for a radio-telemetry study of their habitat use and movements. Community response was very positive and we were able to identify core areas of racer occurrence for our study. All of the black racers we have captured or that were reported to us were within 3 miles of the South shore of the island.
- Funnel trap arrays set in varying habitats where racers were observed. Traps had 4 arms of 50 yards of silt fencing with a central box trap and 8 cone traps
- Traps active May-Sept or until a racer was captured
- Trained volunteers to check trap arrays daily
- Captured racers were implanted with a radio transmitter by a veterinarian and released at their capture site after recovery
- Locate tagged racers 3x/week until hibernation then bi-weekly until emergence in spring
- Documented movements, habitat use, hibernacula characteristics, and nesting areas
- Recapture racers at 11.5 months, transport to veterinarian for transmitter removal, release
To date, we have captured and tracked three adult female black racers and one male black racer:
- Audrey, July 2016 to July 2017 in early successional shrubland and oak pine forest at Long Point Wildlife Refuge
- Katama, July 2017 to April 2018 in sandplain grassland/heathland and a residential area near Katama grass airfield
- Scooter, June 2018 to June 2019 in grassland/heathland and residential area near Stonewall Pond in Chilmark
- Liatris, August 2018 – August 2019 in pitch pine/oak and heathland habitat and residential area along Katama Bay
We track the signal of our black racers until we get as close as possible without disturbing them. They are not always visible, but we are typically within 1 – 2 meters. We have found them in shrubs, up in trees, inside stumps, copulating, and out hunting.
Data from our first two snakes has already provided valuable information on racer habitat use, and the factors influencing their home range and movements on the island. When Audrey was seeking a place to hibernate, she had many options to choose from. The oak and pine forest adjacent to the shrublands she was using had many tree roots with rodent burrows that would allow her to overwinter below the frost line. Audrey visited multiple burrows before settling down for a long winter’s nap. Katama, however, visited a burrow under a road in October and was seen basking near it on several occasions before she began her winter hibernation. It’s possible that Katama had fewer choices as her habitat did not have much pine/oak forest.
While Liatris was also in the Katama area, we never documented her crossing the busy paved road that was the western boundary of her home range in the year that we tracked her. Like Katama, she ranged between grassland/shrubland and developed areas with homes. Her favorite resting spot was under some brick steps at a house, and the owner saw her basking in a shrub outside their living room window one day!
Scooter surprised us when we lost his signal in the Stonewall pond area and found him two days later 3/4 of a mile away on the other side of the pond. He made quite the trek in a short period of time, and during the next 10 months, he did not return to his capture area as we thought he would. When his transmitter battery was about to die, we removed it and attached a temporary external transmitter. That transmitter allowed us to track him another 3 weeks before we found his shed skin and the transmitter in one of his favorite Blacksmith Valley spots. We were bummed to lose the opportunity to track him back to Stonewall Pond, but are grateful for the year we spend learning about Scooter’s life.
We’ll be adding maps for Liatris and Scooter Soon!
Black Racers and Current Threats
Adult black racers are the largest snake on the island, reaching lengths of 4 to 6 feet. On occasion, a large black racer has been mistaken for a garden hose! Sadly, some of these beautiful and harmless snakes are killed by landscapers or homeowners who believe them to be dangerous. Others are run over by vehicles when basking on dirt or paved roads or die tangled in fruit netting in gardens. Another factor limiting their populations is that they require large tracts of habitat with some open/early successional habitat that are are less available today. Black racers, like turtles, may experience high rates of egg predation from predators (raccoons, skunks, and crows), whose populations are abundant due to human food subsidies.
How Can You Help?
- If you use netting to protect fruit in your gardens, please use a small mesh size (less than 1/2″) as the larger mesh is a death trap for the large black racers that sometimes hunt mammals and birds in fruit patches.
- Spread the word that all snakes are harmless on Martha’s Vineyard, and that they are beneficial to have around your yard because they eat rodents and other pests (slugs and bugs)
- Watch for snakes crossing roads or basking on roads. Stop to help them.
- Support habitat conservation by supporting open space protection through your votes and your donations.
- Visit a local library and pick up one of our snake bookmarks to learn how to identify our snake species.
- Map your snake sightings on our snake map by clicking HERE