Status and Population Characteristics Of the Northern River Otter (Lontra Canadensis) in Central And Eastern Oklahoma
Abstract
In 1984 and 1985, the Oklahoma Department of Wildlife Conservation reintroduced 17 northern river otters (Lontra canadensis) in southeastern Oklahoma. In the past, distributional data have been limited to incidental harvest by state and federal trappers and roadkills collected opportunistically. Our goal was to determine the precise distribution of river otters via sign surveys and mail surveys and examine river otter age structure and isotopic (? 13C, ? 15N) signatures in Oklahoma. During winter and spring of 2006 and 2007, we visited 340 bridge sites within 28 different watersheds and identified river otter sign in 11 counties where river otters were not previously documented. Approximately 300 (27%) mail surveys were returned by state and federal natural resource employees, private organizations, and professional and recreational trappers. Mail surveys revealed the possibility of river otters occurring in 8 additional counties where they were not documented previously by published literature, USDA Animal and Plant Health Inspection Service records, or by sign survey efforts. From 2005-2007, we salvaged river otter carcasses from APHIS and ODWC employees and live-captured river otters using leg hold traps. Seventy-two river otters were sampled, and sex ratios were skewed toward females (1F:0.8M). Teeth were removed from salvaged and live-captured river otters (n = 63) for aging. One year olds represented the largest age class (30.2%). Proportion of juveniles within Oklahoma (19.0%) was less than proportions in some states but higher in others where river otters occur. Mean age of river otters decreased from east-to-west in the Arkansas River and its tributaries. Populations in extreme eastern Oklahoma (Arkansas River Watershed) had an older age structure and lower proportion of juveniles than colonizing populations further west (Canadian River Watershed). Tissue ?13C values were less in western areas, which probably resulted from allochthonous inputs of C3 and C4 plants and water velocity differences. Tissue ?15N values decreased in western areas and probably resulted from less suitable habitat and/or older age structures further east.
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- OSU Theses [15752]