A study was implemented to determine the current distribution of the Southern Hognose Snake, Short-tailed Snake, Florida Pine Snake, and Eastern Diamondback Rattlesnake. 2013-2015
Taking a measurement of a H. Simus found during the study
Florida Pine Snake, Pituophis melanoleucus mugitus
Short-tailed Snake, Lampropeltis extenuata
LAMPROPELTIS EXTENUATA (Short-tailed Kingsnake).
Lampropeltis extenuata is a state-threatened species endemic to Florida, USA, that inhabits xeric upland habitats from Columbia Co. south to Highlands Co. In coloration and pattern, L. extenuata resembles the Dusky Pygmy Rattlesnake (Sistrurus miliarius barbouri), but it is much more slender and has a small head approximately the same diameter as its body. Woolfenden (1962. Copeia 1962:648–649) mentioned that an excited captive L. extenuata would occasionally hold its head vertically and jerk it repeatedly to the side. He speculated that this behavior was related to its fossorial habits, because L. extenuata burrows into sand by pressing its nose to the substrate and moving its head up and down. However, burrowing and head-jerking motions differ in their speed and orientation. We believe these rapid lateral head movements mimic those of S. miliarius. We have frequently observed disturbed S. miliarius twitching their upward-angled heads, although we could find no mention of this behavior in the literature (Glaudas et al. 2005. Copeia 2005:196–200). When first encountered in the wild, a L. extenuata will often cock its head sharply upwards with its dark chin facing the observer (Fig. 1), and then twitch it rapidly from side to side. Sporadic head twitching can last for several minutes, and it can be elicited again when the snake detects movement by the observer.
This lateral head-twitching behavior is sometimes accompanied by spasmodic tail waggling and curling that resembles the caudal luring performed primarily by juvenile S. miliarius (Rabatsky and Waterman 2005. Herpetologica 61:87–91). Sistrurus miliarius seldom rattles defensively; its diminutive rattle is relatively ineffective as a warning signal because it is readily shed and produces barely audible rattling sounds when intact (Rowe et al. 2002. In Schuett et al.
[eds.], Biology of the Pit Vipers, pp. 385–404. Eagle Mountain Publ., Eagle Mountain, Utah). The defensive tail movements of L. extenuata do not resemble the rapid, continuous tail vibrations of many nonvenomous snake species that are thought to deflect attention of a predator away from the more vulnerable head (Greene 1988. In Gans and Huey [eds.], Biology of the Reptilia, Vol. 16, pp. 2–151. Alan R. Liss, New York). Excited L. extenuata often strike repeatedly with closed mouths, often lunging so vigorously that the anterior half of their bodies leave the ground. These rapid strikes are delivered while the anterior portion of the body is S-shaped, and the posterior portion is partially coiled like a spring or stretched out in a series of tight S-curves. After a period of time in captivity, these defensive behaviors were seldom observed in L. extenuata, except for occasional head twitching when startled or being manipulated for photographs.
These defensive behaviors of L. extenuata were observed during an attempted predation event. On 30 April 2014 at 0945 hr, G. Craft observed a Fish Crow (Corvus ossifragus) attacking an adult male L. extenuata (450 mm SVL, 495 mm TL, 8.2 g) on a sand road in Hernando Co. (28.6247°N, 82.5060°W; WGS 84). The presence of the vehicle flushed the bird, and the L. extenuata crawled rapidly away, whereas most L. extenuata remain motionless when first approached. All ? L. extenuata found on sand roads during the daytime in Hernando and Marion? counties exhibited this head-twitching behavior, and we have video footage of four? of these snakes.
We have also observed this head-twitching defensive behavior in wild-caught South Florida Mole Kingsnakes (L. calligaster occipitolineata), another Florida endemic taxon that resembles a
robust L. extenuata. Morphologically, neither Lampropeltis species resembles the stockier, large-headed S. miliarius, and their blotched patterns are characteristic of several other snake species. The two Lampropeltis lack the light-colored tail characteristic of young Sistrurus, whereas the Southern Hog-nosed Snake (Heterodon simus), another presumed S. miliarius mimic, resembles it morphologically and possesses a banded, lighter-colored tail. All three nonvenomous mimics typically have yellow, orange, or red coloration between the dorsal blotches like most S. miliarius barbouri. Heterodon simus has a different suite of defensive behaviors that includes neck flattening, body inflation, hissing, and death feigning (Myers and Arata 1961. Q. J. Florida Acad. Sci. 24:108–110). The function of the characteristic hesitant, jerky movements sometimes exhibited by H. simus while slowly crawling forward (Beane et al. 2014. Copeia 2014:168‒175) is unknown but may confuse predators or be another example of behavioral mimicry.
KEVIN M. ENGE, Florida Fish and Wildlife Conservation Commission, 1105 SW Williston Road, Gainesville, Florida 32601, USA (e-mail:email@example.com); GARRETT CRAFT, JORDAN T. SCHMITT, and GLENN L. BARTOLOTTI…..
FIG. 1. Sharply cocked head of an adult male Lampropeltis extenuata from Hernando Co., Florida.
The U.S. Fish and Wildlife Service provided funding to the FWC for status surveys of the southern hognose snake (Heterodon simus), Florida pine snake (Pituophis melanoleucus mugitus) and eastern diamondback rattlesnake (Crotalus ada-manteus), all of which have been petitioned for federal listing as threatened. To determine the current distribution of these spe-cies and the short-tailed snake (Lampropeltis extenuata), reptile and amphibian researchers solicited sightings through online surveys and conducted systematic road surveys. Two seasonal technicians, Steve Christman and Glenn Bartolotti, were hired to conduct most of the road surveys, and Jonathan Mays designed a database to record and summarize the snake survey re-sults.
We designed an occupancy modeling study for the southern hognose and pine snake, selecting 33 survey routes through upland habitats. The routes were approximately 100 kilometers (60 miles) long, and researchers sur-vey each three to seven times from September to November. Driving 16,307 kilometers (10,133 miles) yielded 170 snakes of 20 species (65 percent were alive), but only three southern hognoses and one pine snake. We averaged 0.01 snakes per mile in the peninsula and 0.03 snakes per mile in the panhandle. Black racers (Coluber constrictor) accounted for 40 per-cent of the snakes seen, and diamondbacks were the fourth most common species.
We were much more successful at soliciting snake sightings, receiving credible reports of 54 southern hognose, 163 pine snakes, 32 short-tailed snakes and 659 diamondbacks.
Determine factors affecting species occupancy rates. 3/28/16
Locality records for the 3 nonvenomous species were used to develop MaxEnt potential habitat models. Both southern hognoses and pine snakes prefer open, xeric habitats, including some ruderal habitats, and have experienced some range contraction. These 2 species are still locally common in some areas but have disappeared from urbanized areas. Little is known regarding the fossorial short-tailed kingsnake, but populations appear secure on portions of the Brooksville Ridge.
Update to project 8/26/14
Solicitation of records from the public via 2 FWC webpages, posters, emails, or phone calls produced numerous credible sightings: 90 southern hognose, 44 short-tailed, 231 Florida pine, and 953 eastern diamondback rattlesnake. We ran almost 40 road-survey routes multiple times in September‒November 2013 but detected only 1 pine snake, 3 southern hognoses, and 14 diamondback rattlesnakes (170 specimens of 20 species in >10,000 km). In April‒June 2014, we revised our survey methodology, only targeting areas without recent records of southern hognose snakes and eliminating pre-determined road routes. We drove a total of 10,579 km and detected 1 southern hognose, 1 pine snake, and 7 diamondback rattlesnakes (129 specimens of 20 species). We installed 2 drift-fence arrays each in sandhill habitat at Camp Blanding Military Reservation, Ocala National Forest, St. Marks NWR, and Suwannee Ridge Mitigation Park WEA. There are no recent records of southern hognose snakes from these areas. In April-June 2014, we trapped over 4,000 amphibians and reptiles representing 51 species, including 8 pine snakes at Suwannee Ridge WEA and 3 pine snakes and 1 short-tailed snake at Ocala National Forest. Traps will be run again September‒November. Locations of these species are being used to produce potential habitat maps.
We’ll be soliciting sightings on the webpages at the FWC website for entering observations above.
Eastern Diamondback Rattlesnake, Crotalus adamanteus
Southern Hognose Snake, Heterodon simus
Florida Pine Snake, found May 23, 2015
Short-tailed Snake, Lampropeltis extenuata , found Oct. 18, 2015