. The Canadian field-naturalist. 1996 Ashley and Robinson: Road Mortality on Long Point Causeway 409 (0 0) o Q) Q. CO Iâ a> Q. CO â c o £ o 16 o c CD O CD O m o o CO o CVJ ^Painted Turtle, n = 246 ^Snapping Turtle, n = 197 E3Blanding's Turtle, n = 36 Garter Snake, n = 88. "00 ^ "O :=gO ^0 )0 )0 â -30 00 -00 -oo 1 1 Apr. May June July Month Aug. Sept. Oct. Figure 3. Monthly road mortality of selected reptiles on the Long Point causeway as a percent of total road mortality per species 1980, 1992, 1993 (1979 data excluded). Blanding's and more aquatic Map Turtle {Graptemys geographi
. The Canadian field-naturalist. 1996 Ashley and Robinson: Road Mortality on Long Point Causeway 409 (0 0) o Q) Q. CO Iâ a> Q. CO â c o £ o 16 o c CD O CD O m o o CO o CVJ ^Painted Turtle, n = 246 ^Snapping Turtle, n = 197 E3Blanding's Turtle, n = 36 Garter Snake, n = 88. "00 ^ "O :=gO ^0 )0 )0 â -30 00 -00 -oo 1 1 Apr. May June July Month Aug. Sept. Oct. Figure 3. Monthly road mortality of selected reptiles on the Long Point causeway as a percent of total road mortality per species 1980, 1992, 1993 (1979 data excluded). Blanding's and more aquatic Map Turtle {Graptemys geographica) had lower road mortality although the populations of these latter species do not appear as high as the Painted and Snapping Turtles. The most common snake road mortality was the Eastern Garter Snake (Thamnophis sirtalis sirtalis) (n = 114). Annual road mortality of both Garter Snake and Fox Snake were the greatest in 1980. An important factor in the composition of road mortality is the time of day the causeway is occupied by wildlife. Mature reptiles tend to occupy the causeway during the afternoon, which increases the likelihood of collisions, especially species that bask on the highway and use it as a thermoregulatory source. Conversely most amphibian migration across the causeway occurs at night when use by motorists is at a daily minimum. Several studies have addressed the issue of traffic volume on anuran population densities. A study of the breeding migration of the Common Toad {Bufo bufo) by van Gelder (1973) estimated that 60 cars/hour passing by his site would kill ninety per- cent of the adult toads during breeding migration. Reh and Seitz (1990) report two other studies on the impact of road mortality orr the Common Toad. In the first, Kuhn (1987) found that 50% of the migrat- ing toads at his site were killed at a traffic volume of 24 - 40 cars per hour, and Heine (1987) concluded that a rate of 26 cars per hour passing by his site would kill all migrating
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