Biological Conservation 106 (2002) 187–197 www.elsevier.com/locate/biocon Florida panther dispersal and conservation David S. Maehra,*, E. Darrell Landb, David B. Shindleb, Oron L. Bassc, Thomas S. Hoctord aUniversity of Kentucky, Department of Forestry, 205 Cooper Building, Lexington, KY40546-0073, USA bFlorida Fish and Wildlife Conservation Commission, 566 Commercial Boulevard, Naples, FL 34104, USA cNational Park Service, Everglades National Park, Research Center, Homestead, FL 33030, USA dUniversity of Florida, Department of Wildlife Ecology and Conservation, PO Box 115706, Gainesville, FL 32611-5706, USA Received 8 March 2001; received in revised form 4 September 2001; accepted 16 September 2001 Abstract We studied dispersal in 27 radio-collared Florida panthers Puma concolor coryi in southern Florida from 1986 to 2000. Male dispersal was longer (mean=68.4 km) than that of females (mean=20.3 km), tended to be circular, frustrated, and of insufficient length to ameliorate inbreeding. Females were philopatric and established home ranges that were less than one home range width away from their natal ranges. All females were successful in establishing territories, whereas males were successful 63% of the time. Dispersing panthers avoided moving toward the southeast and into an area of limited forest cover. Independence and the initiation of dispersal occurred at about 14 months of age and lasted for an average of 7.0–9.6 months for females and males, respectively. On average, Florida panthers disperse shorter distances than are typical for western populations of Puma concolor. A recent increase in long distance male dispersal events may be related to an increase in reproduction and population density resulting from the intro- duction of female cougars P. c. stanleyana into south Florida. Although the population exhibits the behavioral ability to colonize nearby vacant range, females have yet to do so. Successful dispersal to these areas could be facilitated by habitat restoration and translocation of females. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Dispersal; Florida panther; Puma concolor coryi; Colonization; Conservation planning; Frustration; Circular movements 1. Introduction annual survival rates (Maehr and Caddick, 1995), its pattern of dispersal most closely follows the model of The influence of dispersal on the genetic and demo- frustration where territory-seeking individuals are graphic structure of vertebrate populations is poorly mostly unsuccessful in establishing home ranges understood because this aspect of behavior is often dif- (Lidicker, 1975, 1988, 1991). Frustrated dispersal can ficult to observe (Lidicker and Patton, 1987). The occur when insufficient vacant range exists to accom- endangered Florida panther Puma concolor coryi has modate dispersers, or when suitable vacant range does been described as a highly inbred population with lim- not contain individuals of the opposite sex. ited dispersal potential due to landscape barriers One component of panther recovery should be the (Maehr, 1992, 1997a). Over a span of two decades, restoration of recruitment patterns that lead to detailed natural history research has failed to document increased population size. This would result in the successful emigration or immigration in a population reduction of inbreeding, the promotion of population that has numbered fewer than 100 for many decades stability (Murphy et al., 1999), and minimize the need to (Maehr et al., 1991). Although the Florida panther has introduce non-Florida individuals into the population. exhibited demographics typical of western cougars An understanding of dispersal patterns in this endan- (Ashman et al., 1983; Hemker et al., 1986; Lindzey et gered subspecies will be necessary for updating recovery al., 1988), including high juvenile (<1 year) and adult plans, modifying reserve designs (Van Vuren, 1998), and will be helpful in understanding the forces that influence * Corresponding author. Tel.: +1-859-257-4807; fax: +1-859-323- successful dispersal in wide-ranging, solitary carnivores. 1031. In western populations of Puma concolor both males E-mail address: [email protected] (D.S. Maehr). and females exhibit sufficient dispersal abilities to link 0006-3207/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0006-3207(01)00245-2 188 D.S. Maehr et al. / Biological Conservation 106 (2002) 187–197 disjunct populations (Logan et al., 1986; Sweanor et al., and to facilitate commercial and recreational boat travel 2000; Beier, 1995; Pierce et al., 1999). The Florida pan- throughout the region. Expansive sugarcane farms in ther is separated by >2000 km from the nearest known the northern Everglades cover >1780 km2 and have cougar population as a result of a highly denatured and replaced most interior native plant communities includ- barrier-rich landscape. Due to its peripheral distribution ing a continuous band of pond apple Annona glabra that and position at the end of a peninsula, the panther in historically connected the west coast and east coast with south Florida likely experienced higher rates of pre- forest (McCally, 1999). The largest concentration of Columbian inbreeding than western populations drainage canals exists in the eastern portion of south (Maehr, 1997b), and its modern isolation has led to Florida (US Department of the Interior, 1974), however, management intended to ameliorate the total absence of the Caloosahatchee River was dredged in the late 1800s immigration. Since 1995 eight adult females from Texas to connect Lake Okeechobee with the Gulf of Mexico have been added to the population to enhance genetic (Carter, 1974). This artificial waterway is wide enough to variability and to simulate natural gene flow (Land and accommodate maritime shipping and has steep-sided Lacy, 2000). This paper focuses on juvenile Florida banks where dredging and channel-creation have occur- panther dispersal over a 15-year period, and examines red. In addition to extensive anthropogenic habitat frag- the influences of gender, social structure, genetic intro- mentation, the south Florida landscape exhibits an gression, and dispersal distance on the potential for the increasingly patchy forest distribution from northwest to population to expand. southeast (Maehr, 1997a). Reduced forest abundance and increased forest patchiness have been linked to high 1.1. Study area demographic stochasticity in the local Everglades pan- ther subpopulation (Bass and Maehr, 1991). South Florida is characterized by subtropical vegeta- tion, a high water table, and flat topography that ranges from sea level to 9 m above mean sea level (Davis, 2. Methods 1943). Detailed descriptions of vegetative communities can be found in Davis (1943), Kushlan (1990), Duever Radio-collared Florida panthers were tracked at least et al. (1979), and Maehr (1997a). Large scale landscape three times each week from fixed-wing aircraft. Details patterns that may influence Florida panther dispersal of capture, handling, and radio telemetry can be found include the Everglades ecosystem—a predominantly in McCown et al. (1990), and Maehr et al. (1989a). We sedge-dominated wetland that once covered more than were alerted to births when female panthers reduced 10,000 km2 in southeastern Florida; the Big Cypress movements to a small portion of their home ranges. Swamp—a forested system that is a matrix of cypress Searches for kittens were used to verify den locations swamps, upland pine forests, and a productive agri- and to examine kittens when they were approximately cultural region that covers 6,400 km2 (Duever et al., two weeks old (Land et al., 1998). Efforts to capture and 1979); and expanding urban and residential centers that radio-instrument kittens were made at about 6 months- are located on the coasts of the Atlantic Ocean and Gulf of-age by using the radio signal of the adult female as a of Mexico (Fig. 1). The southern portion of inhabited homing beacon to the family. Trained hounds were used range is demarcated by an extensive mangrove swamp to chase and tree study animals for radio-collaring. The on the edge of Florida Bay that is the only forest com- same procedure was used to recapture adults for routine munity avoided by panthers (Maehr et al., 1991). High- collar replacement and to accommodate neck growth of ways including Interstate 75, US 41, US 27, US 1, State kittens. Recaptures of kittens occurred 3–12months Highway 29, and several other state and county roads after initial captures, depending upon their age and encircle and bisect occupied panther range in south projected growth (Maehr and Moore, 1992). After this Florida (Maehr and Cox, 1995). Highways account for time, radio collar replacements were scheduled at 2–3 at least 1300 km of pavement in south Florida, and year intervals primarily to replace aging transmitters. cover more than 1160 km2. Maehr and Cox (1995) We defined independence and the start of dispersal as found that the average patch of habitat encircled by the first date that a juvenile panther was separated paved highways and that was occupied by panthers was from its mother by at least one week. We used this time >53,320 ha, and that the likelihood of occupation period because energy demands require solitary pan- declined with decreasing patch size. thers to make approximately one deer-sized kill per Maehr (1997a) suggested that the only known breed- week (Ackerman et al., 1986). Dispersal was measured ing population of the Florida panther was isolated from the estimated moment of independence to (1) the south of Lake Okeechobee as a result of urbanization first encounter with an adult male if the disperser was at and construction of drainage canals. Canals are fre- least 18 months old and female (Maehr et al., 1989b) or quently associated with agricultural lands, and have if both animals remained together for >2consecutive been constructed to control flooding in Lake Okeechobee flights; (2) the death of the disperser if it preceded sexual D.S. Maehr et al. / Biological Conservation 106 (2002) 187–197 189 Fig. 1. The study area spanned half of the Florida peninsula from the southern terminus to Orlando.