Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology, Animal Behavior

Date of Defense

12-16-2005

Graduate Advisor

Godfrey R. Bourne, Ph.D.

Co-Advisor

Zuleyma Tang Martinez, Ph.D.

Committee

Kellogg, Elizabeth A

Bette Loiselle, Ph.D.

Abstract

I studied the spacing patterns and habitat utilization by reintroduced northern river otters, Lontra canadensis, at two sites in Missouri because previous studies of otters indicate, plasticity of a species social structure will likely be due to the tactics employed in acquiring resources in any given area. Seven hypotheses were tested by employing radio-tracking, habitat assessment and geographic information system approaches: (1) home range (HR) and core area (CA) size differ by sex; (2) HR and CA size differ in breeding vs. non-breeding seasons; (3) percent range overlap differs by sex; (4) habitat utilization, as indicated by latrine use, differs seasonally; (5) primary prey type(s) found in scat differ seasonally; (6) environmental characteristics of areas used extensively by otters (latrines, dens, haul-outs) differ from adjacent, unused sites; and (7) stream-order effects and features associated with core area use are similar between two disjointed field sites, and can thus be used along with GIS-driven identifiers to generate predictions regarding suitable habitat for Midwestern river otter populations. Evidence is presented on differences in ranging patterns of otters by location, sex, and seasonality, as well as differences in core area use and accompanying habitat characteristics for the two populations. The following hypotheses were corroborated: (1) male otters had larger HRs and CAs than female otters; (2) female otters maintained small, non-overlapping home ranges; (3) males exhibit a greater percentage of inter- and intra-sexual HR and CA overlap than females; and (4) HR and CA size, and percent overlap differ between a large, riverine ecosystem and a small, meandering stream ecosystem. However, hypotheses examining temporal use of space by otters were not supported. In conclusion, this study suggested that northern river otters exhibit a variety of spacing patterns in different parts of their range, similar to those discovered in other solitary carnivores. Seasonal use of space was different from that typically found in solitary carnivores; differences may be related to habitat characteristics associated with stream order and wetland ecosystems. Overall, although introduced otters came from disjointed regions differing in habitat features and ecological pressures, reintroduced otters have done very well in Missouri.

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Biology Commons

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