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ABSTRACT: ABSTRACT Short-distance translocation (SDT) is commonly used to mitigate snake-human interactions, yet little is known about its effectiveness or its effects on behavior and welfare of snakes. Between April 2004 and October 2005, we evaluated SDT as a conservation and management tool by investigating how 500-m SDT affected spatial ecology, body condition, and behavior of western rattlesnakes (Crotalus oreganus) surgically implanted with radiotransmitters in a field study near Osoyoos, British Columbia, Canada. Of 14 rattlesnakes subjected to SDT, 12 (85.7%) returned on ≥1 occasion (range 1–7 times) to the general area they were removed from. Rattlesnakes that underwent SDT showed an increase in total distance moved over an active season compared to non-translocated snakes, but there was no evidence to suggest SDT had an effect on activity range size. There was no evidence to suggest SDT affected body condition, behavior, or mortality rates. Short-distance translocation to high-quality undisturbed habitats was unsuccessful as a long-term solution to snake-human conflict because most translocated snakes returned to conflict areas within a short time (x̄x = 19.9 ± 8.7 days). However, SDT may be an effective short-term tool to manage snake-human conflict in areas where human presence is seasonal or short-lived if careful attention is paid to species-specific biological needs, habitat quality at the release site, and the location of the release site in relation to conflict areas.
Journal of Wildlife Management 12/2010; 73(3):419 - 425. · 1.52 Impact Factor
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ABSTRACT: To assess intra-clutch variation in contaminant concentrations in eggs, and to investigate the dynamics of chlorinated hydrocarbon accumulation in embryos of the common snapping turtle (Chelydra serpentina), concentrations of p,p DDE, hexachlorobenzene, trans nonachlor, cis-chlordane, and six PCB congeners were measured in eggs, embryos, and hatchhngs Samples were collected from Cootes Paradise, a wetland at the western end of Lake Ontario, Ontario, Canada The intra-clutch variation in chlorinated hydrocarbon concentrations within four snapping turtle clutches was determined by analyzing the first, last, and middle five eggs oviposited in the nest The first five eggs had the highest mean concentrations of all chlorinated hydrocarbons (wet weight basis), wet weight, and egg diameter On a lipid weight basis, the first five eggs contained the highest concentration of all compounds except total PCBs and cis chlordane The concentration of as chlordane (lipid weight basis) was the only parameter measured that was significantly different among the three sets of eggs At hatching, snapping turtles without yolk sacs contained from 55 2 to 90 5% of the absolute amount of organochlorine compounds measured in the egg at oviposition Eighteen days after hatching, the body burden of PCBs and pesticides decreased to 45 3 to 62 2% of that in the fresh egg The accumulation of organochlorine chemicals in embryonic turtles peaked at or just before hatching and then declined thereafter, which is consistent with trends reported in developing sea turtles, fish, and birds
Environmental Toxicology and Chemistry 10/2009; 14(3):421 - 426. · 2.81 Impact Factor
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ABSTRACT: Some organochlorine pesticides and industrial chemicals may alter sexually dimorphic traits through endocrine disruption. Therefore, we examined a sexually dimorphic trait, precloacal length, of hatchling snapping turtles (Chelydra serpentina) incubated from 31 clutches from a heavily contaminated site (Hamilton Harbour, ON, Canada; n = 14), a moderately contaminated site (Akwesasne Mohawk Territory; n = 3), and from a reference site (Algonquin Provincial Park, ON, Canada; n = 14). The mean sum polychlorinated biphenyls from Algonquin were low (20.33 ng/g wet wt), but were high from both Hamilton and Akwesasne (2,956.28 and 3,377.0 ng/g wet wt, respectively). Organochlorine pesticides, such as dichlorodiphenyldichloroethylene, were low from Algonquin (1.67 ng/g wet wt), moderate from Akwesasne (10.00 ng/g wet wt), and relatively high from Hamilton (135.14 ng/g wet wt). At all sites, the precloacal length of male hatchlings was larger than that of females by an equal amount at any given body size. However, the precloacal length of both males and females from Hamilton increased with body size at a slower rate than of males and females from the other two sites. Our results support an earlier study that found differences in sexually dimorphic morphology of adult snapping turtles among contaminated and uncontaminated sites. Furthermore, these alterations in secondary sexual characteristics previously observed in adults likely are initiated early in development, and may result in permanent organizational changes in morphology.
Environmental Toxicology and Chemistry 06/2002; 21(5):922-9. · 2.81 Impact Factor
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ABSTRACT: The gonadal estrogen estradiol-17beta (E(2)) is important for developing and regulating hypothalamic function and many aspects of reproduction in vertebrates. Pollutants such as octylphenol (OP) that mimic the actions of estrogens are therefore candidate endocrine-disrupting chemicals. We used a differential display strategy (RNA-arbitrarily primed polymerase chain reaction) to isolate partial cDNA sequences of neurotransmitter, developmental, and disease-related genes that may be regulated by OP or E(2) in the snapping turtle Chelydra serpentina serpentina hypothalamus. Hatchling and year-old male snapping turtles were exposed to a 10 ng/mL nominal concentration of waterborne OP or E(2) for 17 days. One transcript [421 base pairs (bp)] regulated by OP and E(2) was 93% identical to human APLP-2. APLP-2 and the amyloid precursor protein (APP) regulate neuronal differentiation and are also implicated in the genesis of Alzheimer disease in humans. Northern blot analysis determined that the turtle hypothalamus contains a single APLP-2 transcript of 3.75 kb in length. Exposure to OP upregulated hypothalamic APLP-2 mRNA levels 2-fold (p < 0.05) in month-old and yearling turtles. E(2) did not affect APLP-2 mRNA levels in hatchlings but stimulated a 2-fold increase (p < 0.05) in APLP-2 mRNA levels in yearling males. The protein beta-amyloid, a selectively processed peptide derived from APP, is also involved in neuronal differentiation, and accumulation of this neurotoxic peptide causes neuronal degeneration in the brains of patients with Alzheimer disease. Therefore, we also sought to determine the effects of estrogens on the expression of beta-amyloid. Using homology cloning based on known sequences, we isolated a cDNA fragment (474 bp) from turtle brain with 88% identity to human APP. Northern blot analysis determined that a single 3.5-kb transcript was expressed in the turtle hypothalamus. Waterborne OP also increased the expression of hypothalamic APP after 35 days of exposure. Our results indicate that low levels of OP are bioactive and can alter the expression of APLP-2 and APP. Because members of the APP gene family are involved in neuronal development, we hypothesize that OP exposure may disrupt hypothalamic development in young turtles.
Environmental Health Perspectives 03/2002; 110(3):269-75. · 7.04 Impact Factor
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ABSTRACT: Summary1. Variation in resource allocation to egg size and number was investigated in seven sympatric species of Piophilidae that oviposit on carcasses or discarded cervid antlers: Liopiophila varipes (Meigen), Prochyliza xanthostoma Walker, Protopiophila latipes (Meigen), Protopiophila litigata Bonduriansky, Stearibia nigriceps (Meigen), and two unidentified species of Parapiophila McAlpine.2. Following optimal reproductive allocation theory, relatively larger, fewer eggs were expected in (1) species that oviposit on antlers, where larvae probably experience lower risk of predation and greater competition than larvae in carcasses, and (2) species with aggressive males and male-biased sex ratios on the oviposition substrate, where risk of injury during oviposition may have favoured females laying fewer eggs.3. Variation in reproductive allocation strategies could not be explained by known differences in larval or adult environment, but congeneric species clustered by reproductive allocation patterns. The Parapiophila species produced larger, fewer eggs than the other species, and egg number increased slowly with body size. The Protopiophila species did not deviate from expected egg sizes and numbers, and egg number increased steeply with body size.4. An interspecific egg size–egg number trade-off resulted in a tight linear scaling of ovary volume to body size, suggesting common physiological constraints on relative ovary mass.5. Within each species, egg size was nearly constant whereas egg number increased with female body size, suggesting species-specific stabilising selection on egg size.
Ecological Entomology 12/2001; 24(4):389 - 395. · 2.00 Impact Factor
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ABSTRACT: 1. Destructive subsampling or restrictive sampling are often standard procedures to obtain independence of spatial observations in home range analyses. We examined whether home range estimators based upon kernel densities require serial independence of observations, by using a Monte Carlo simulation, antler flies and snapping turtles as models.2. Home range size, time partitioning and total straight line distances travelled were tested to determine if subsampling improved kernel performance and estimation of home range parameters.3. The accuracy and precision of home range estimates from the simulated data set improved at shorter time intervals despite the increase in autocorrelation among the observations.4. Subsampling did not reduce autocorrelation among locational observations of snapping turtles or antler flies, and home range size, time partitioning and total distance travelled were better represented by autocorrelated observations.5. We found that kernel densities do not require serial independence of observations when estimating home range, and we recommend that researchers maximize the number of observations using constant time intervals to increase the accuracy and precision of their estimates.
Journal of Animal Ecology 12/2001; 68(2):221 - 234. · 4.94 Impact Factor
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Chelonian Conservation and Biology 01/2001; 4:187-189. · 0.91 Impact Factor
