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Wildlife Road-kills in a Southeast Florida Park
A Steward’s Circle Note Robin J. Rossmanith, and Henry T. Smith Road-kills of wildlife are an international conservation dilemma (Skoog 1982; Smith et al. 1994; Trombulak and Frissell 2000; Hels and Buchwald 2001; Bard et al. 2002; Fahrig et al. 2002; Smith et al. 2003). Wildlife killed by vehicles has prompted investigators to research ways to mitigate kills including reduced speed limits, physical barriers, and environmental education (Foster and Humphrey 1995; Bertwistle 1999; Brown et al. 1999; Evink 1999; Phillips 1999; Bard et al. 2002; Foresman 2002). This note reports wildlife mortality due to collisions with vehicles during 1995 to 1998 at Jonathan Dickinson State Park (JDSP), a 4644.1 ha, mixed-use state park located approximately 40 km north of West Palm Beach, on Florida’s southeast coast. JDSP is a mix of uplands and wetlands, consisting mostly of four ecosystems: wet pine flatwoods (1983.8 ha), scrub (935.2 ha), strand swamp (370.9 ha), and wet prairie (351.8 ha; Florida Park Service, 2000). Methods: An opportunistic, daily road-kill survey was conducted during 1995-1998 by JDSP park staff and consisted of slowly searching road surfaces (ca. 8-24 km/hr.) for dead wildlife (i.e. Smith et al. 1994; Bard et al. 2002). At JDSP, ca. ten km of paved, two-lane road (with widely variable speed limits of 24.2- 48.4 km/hr) were first driven daily between 0745 and 0815 and provided opportunistic collection of vertebrate wildlife taxa struck by moving vehicles. Animals were identified to species when possible. Results: Eighty mammals, 26 birds, 217 reptiles, and 39 amphibians were recorded as road-kills during the study (Table 1). There was a significant difference in road-kill frequency goodness of fit between the four pooled classes of animals (x2 = 253.31, df = 3, P < 0.05, Table 1). Armadillos (Dasypus novemcinctus) had the highest frequency (23) among mammals and black racers (Coluber constrictor; 42) and garter/ribbon snakes (Thamnophis spp.; 41) were the most frequent reptiles killed. Birds and amphibians exhibited no clear trends in vulnerability. |
Discussion: While managing for natural
resources and resource-based human recreation
it is inevitable that humans will impact the
natural resources. Ten species of mammals,
most commonly the exotic nine-banded
armadillo (23), were found (Layne 1997). We
conjecture that armadillos have achieved a
relatively high population-density at JDSP,
and combined with a predilection for foraging
along disturbed roadside areas, are extremely
vulnerable to road-kill events. We were
surprised that another common exotic mammal,
feral hog (Sus scrofa) was never found to be
killed by a vehicle (Engeman et al. 2003). We
attribute this phenomenon to the wariness of the
species (Saunders and Bryant 1988).
Sixty percent of the animals killed by vehicles were reptiles (52% snakes) and 11% were amphibians. The high number of reptiles killed on roads can probably be attributed to their ectothermic nature (Pough et al. 2001). Conversely, the low number of amphibians found could be partially explained by three theories: (1) typically amphibians are smaller in body size than the other classes of vertebrates and therefore less likely to be struck by vehicles; (2) and many amphibians found in JDSP are nocturnally active, when humans are less likely to drive; and (3) the small sizes of amphibian road-kills may contribute to them being overlooked during surveys. Protective closures and buffer zones have been |
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