This August, the Phoenix Zoo, along with four other Association of Zoos and Aquariums (AZA) facilities, contributed to reintroduction efforts of the Louisiana pine snake. The snake is native to the longleaf pine ecosystem in northwestern Louisiana and eastern Texas. Originally found in nine parishes in Louisiana and 14 counties in Texas, as a result of habitat loss, they currently exist in only a few Louisiana parishes and have been extirpated from Texas. Heavy commercial logging occurred from 1870 to 1920 in this area resulting in significant habitat loss with only 3 percent of the longleaf pine habitat remaining by 1935. The rest of the habitat was converted to faster growing tree species planted in very close closed canopy stands destroying habitat for the pocket gophers, which is the snakes main prey item. Louisiana pine snakes spend a majority of their time underground, relying on the gophers not only for food, but also for shelter in the gophers’ burrow systems. They use these burrows throughout the year, even overwintering in them from December to February.
Louisiana pine snakes are large, heavy-bodied colubrid snakes, potentially exceeding five feet in length. They also boast the largest eggs and hatchlings of any North American snake species. Eggs are typically five inches long by two inches wide, and hatchlings can be 18 to 22 inches long and weigh nearly four ounces. Louisiana pine snakes have relatively small clutches, however, averaging only three to five eggs per clutch. This low reproductive output magnifies the threats faced by these snakes.
The Zoo currently houses one adult pair of Louisiana pine snakes. They are currently housed off exhibit in one of the reptile buildings. The temperature and light cycle of the enclosures are adjusted seasonally to simulate natural environmental changes. These temperature and light changes are critical cues for breeding to occur. When the snakes are brought out of their winter brumation (or cooling) period, the females ovulate and the males produce sperm. During this period, the snakes are introduced into the same enclosure for breeding. After mating, the male is removed and the female is monitored for egg development. The female nests about 21 days after mating. The eggs are removed and artificially incubated by Zoo staff at about 84 degrees F. The eggs hatch after an average incubation term of 60 days.
Louisiana pine snakes are part of a cooperative effort by several different AZA-accredited zoological institutions across the US as well as the US Forest Service. Each pair of snakes is managed by the Species Survival Plan® (SSP) program coordinator. As with all SSPs, animals are carefully paired to maintain high genetic diversity within the population. The pair housed at the Zoo has had approval to breed for the past two years and has successfully bred both years. Last year’s clutch of hatchlings is set to enter the captive population of Louisiana pine snakes and will be sent to other zoos currently working with the Louisiana Pine Snake SSP program. On Thursday, August 13, this year’s hatchlings were released in Grant Parish, Louisiana to help add numbers to the wild population. Since 2010, over 70 snakes have been released at this site.