Home Range and Seasonal Act ivity of the Eastern I�d igo Snake, Drymarchon cora is couperi, in Northern Florida by Paul E. Moler INTRODUCTION Tne eastern indigo snake, Orymarchon cora is couperi, is tht> long�st spe�i-:!s of snake in th e United States (Conant 1975). Most accounts .of its natural 'h istory ·have emphasizt!d its assoc iation with xeric sand ridge hab itats (sandhills) and its dependence on th� burrows of the gopher torto iie (Gopherus po·lyphemus) for overw inter ing (�/right and Wright 1957, Mount 1975, lawler 1977, Speake et al. 1978, Landers and Speake 1980, Speake and McGlincy 1981; U.S. Fish and Wildlife Service 1982, Diemer and Speake 1983). Although acknowl edgi rig that the ind igo snake inhabits a wide var iety of hab itats in south Flor ida, many authors have reported that it is largely restr icted to xeric hab itats farther· north (Carr 1940, Lawler 1977, USFWS 1982). L·awler (1977), for example, states, "In Florida, Orymarchon remains int imately assoc iated with the sandhill habitat north of lake Okeechobee, although it is not uncommon to find wandering ind ividuals in decidedly mes ic situat ions". Although the indigo snake is apparently rore or less restr icted to the vicin ity of sandh ill hab itats in Georg ia (D iemer and Speake 1983) and the western Flor ida panhandle, th is observation has overshadowed the fact that it occupies a wide var iety of non-xer ic habitats throughout the Florida peninsula. In the central and northern portions of the Florida peninsula, the indigo snake does occur in xeric hab itats, and in such situations may well require gopher tortoise ,burrow_s as refuge's fr om both the .cold of winter and the des iccating heat of summer (Bogert and Cowles 1947). However, it is not restr icted to such habitats, occurring regul�rly in·� var iety of other habitats far removed from sandh ills and gopher tortoises. It is common, for example, in cabbage palm (Sabal palmetto) dominated hammocks iri eastern Orange County . --· (R. Demmer, personal communication) and hydric hardwood hammocks of coastal Levy County. At Saint Marks Nat ional Wildlife Refuge, Wakulla County, indigo 2 snakes are uncommon, but roost sight i ngs have occurred in areas of extens ive mesic habitat (C. Gidden, personal commun icat.ion). This study was initiated in 1981 to investigate habitat ut ilization by indigo snakes in coastal hydr ic hammock habitats of. the northern Florida peninsul a. Major funding was provided by the U.S. Fish and Wildlife Serv ice · under Sect ion 6 of the Endangered species Act. As a· resul t of budget cuts, federal fun ding was discontinued after one year, and this study was terminated. Although the study was not cam p 1 eted, much data were co11 ec ted, and it is the purpose of this paper to make available information on movements, hab itat utilizat ion and winter ing behavior of indig o snakes in a non:-xeric hab itat in northern Florida� STUDY AR EA The study was conducted in Gulf Ham mock Wildl ife Management Area north of Yankeetown, Levy County, Fl orida. Gulf Hammock WMA is a 12,000 ha publ ic hunt ing area 'leased by the Fl orida Game and Fresh Water Fish Com mission from Georgia-Pac ific Corporat ion, It is. bordered to the west by Waccasassa Bay State Preserve, an area of extEnsive coastal salt marsh. The area is general ly less than 6 m e.levation above sea level. Two of the snakes were caught and tracked in areas of approximately 1.5 el evation near the western boundary of m the study area. ·The remaining threi snakes were caught and tracked in an area lying bet�een 3-4.5 m elevation. · The area is poorly drained and includes numerous shal low seasonal ponds. Soils are thin, and limestone ,bedrock is near the surface. The area was originally cove red by hydr.ic hardwood hammock,· but has been extensively 3 clear-_cut. Older cleared areas have been site-prepared by windrowing and planted · with slash pine (Pinus .elliottii) . Areas more recently cleared have received no site preparation or have been site-prepared by windrowing, but have not been planted with pines. Success of the planted pine� is spotty, and even within the planted areas there are extensive regions with few pines. Most of the cleared areas utilized by snakes in this study had been cut 3-10 years earlier and were thickly overgrown with a variety of saplings and shrubs. Private inholdings provided patches of mature hammock, and all five snakes had access to both cut and uncut .habitats. Although most trees had been removed, c�bbage palms �nd live oaks (Quercus virginiana) are.of little commercial value and had not been cut. Cabbage palms grew principally in the wetter areas and around ponds. The large live oaks stood as sentinels scattered widely through the e�tensive clear-cuts. The bases of these oaks generally were surrounded by earth· m6unds with hol�s left by rotted root channels or rodent burrows. MATERIALS AND METHODS Five adult indigo snakes wer e captur ed in the study area, equipped· with surgically implanted tr ansmitter s and returned to the sites where they were captured. Table 1 provides vital statisti.cs for the animals tracked. The single female was equipped with an AVM Instrument Company SB2-tV transmitter powered by an EVEREADY Hg601 me.rcury battery; package weight was 33 grams. The males were substantially larget and able to accomod�te a larger transmitte� ·package. Three males received AVM SB2 transmitters powered by two Panasonic 2/3A lithium batteries. All fotir of the above transmitters were equipped with. 46 em long antennas made of 32 gauge Teflon coated hook-up wire (Alpha Wire 4 Corporation). The transmitter-battery packages were potted in dental acrylic and then dip ped in a 1: 1 mixture of beeswax and paraffin; 582 packages measured 6 em X 3.3 em X 1. 6 cm and weighed 43 g. The fifth snake was equipped with a cylindrical preassembled Telonics transmitter weigh ing 30.1 g. and m asuring e 6 em X 2 em. This unit was equipped with a 44 em long braided stainless steel antenna. Transmitters operat d at frequencies between 150.000 and 152.000 e MHz. Transmitters were surgically implanted following the methods of Reinert and Cundall (1982). Snakes were anesthetized by placing them in a closed glass container with a small gauze pad ·onto which Halothane had been poured. Once anesthesia had been induced , the snake was removed from the container, and an incision was made throu gh the skin above the second scale row approximately 3/4 of the way back from the head. A subcutaneous pocket was worked ventrally . below the ribs, and blunt dissection was used to open the peritoneal cavi ty. A finger was used to create an intraperitoneal pocket, and the transmitter was inserted. A 56 lorig piece of stainless ste �l tubing (sharpened on one end) em was beneath the lateral skin forward from the incision a su fficient run distance to accomodate the antenna, and the antenna was inserted into the tubing. The tubing was then removed through the skin at .its forward end. Thus , the antenna was implanted subcutaneou sly alo�g the side of the body. The incision was then sutured. Prior to implant tion the tr��smitters were soaked a f6r several hours in an antiseptic solution, but no antibiotics were ap pl ied to the .transmitter or admin1stered to the snakes. 5 The snakes recovered from the anesthesia within an hour . Each snake was returned to its originai capture site and released within 6-12 days following tran$mitter implantation. Subsequent observations indicated that the incisions healed quickly and without apparent infection. Tracking was usually conducted at periods of 1-8 days (.x = 3.8) fr.om early December 1981 to mid-July 1982. Following termination of the project, the area was revisited 6 times between 18 July 1982 and 7 Apr il 1983 at intervals of 20, 14, 58, 31, 50 and 90 days. Snakes were tracked with a Telonics receiver equipped with a hand-held H antenna. The range of the transmitters used with the male snakes was at least 1.2 km in open country, but varied under field conditions depending upon location of the snake and density of the vegetation. Locations of snakes were determined either by triangulation fr om known points or by pacing the distance and .using a compass to determine direction back to a known point. Locations were plotted on aerial photographs and then mapped on a grid overlay; x and y coordinate values were assigned to each site. Home range estimation follows Jennrich and Turner (1969). For calculation of winter home range, each radiolocation was treat�d as a separate sample· point, even though the snake was often tracked to the same point on consecutive tracking visits. For calculation of total home range and summer home r�nge, location was included only once unless the snake left the area a and then returned to the site a second time. For example, during the process of shedding, snakes typically remained in one spot for periods of 10-20 days. Although the snake might have been found at the same site on three or four 6 consec�tive tracking visits, the site was included only once in determining total anq summer home ranges. RESULTS The five snakes were regularly tracked for periods of 134-178 days.