Date of this Version
River otters (Lontra canadensis) are native to Nebraska but were extirpated by the early 1900s. The Nebraska Game and Parks Commission (NGPC) reintroduced river otters during 1986–1991 to restore the species in the state but little is known regarding the habitat needs and status of this high profile threatened species. To provide information for management I conducted research to determine home range, habitat use, overnight movement distance, and annual survival of river otters in the central Platte River of Nebraska.
I trapped, implanted telemetry transmitters, and tracked 18 river otters during 2006–2009. I obtained 996 locations and constructed 13 annual home ranges. Mean home range size using the 95% fixed kernel (FK) method was 3,711.6 ha (SD = 2,995.4) and 1,361.0 ha (SD = 1,075.2) using the 95% minimum convex polygon method (MCP). Male home ranges were larger than females for both FK (P = 0.02) and MCP methods (P = 0.02). Habitat use was determined by comparing used versus available habitats using compositional analysis. Open water was used more than any other habitat type in all three comparisons tested.
I recorded 19 overnight movements (465 total telemetry locations) for four river otters during 2007–2008. Mean distance moved overnight was 3.5 km (SD = 3.0). Movements during Jan–Feb when NGPC conducts bridge surveys were lower than during the rest of the year (P = 0.03). Annual survival was 100% as no river otter mortalities were detected during the study (Oct 2006–Dec 2009). The mean number of days that a marked river otter was known to be alive was 470.5 (SD = 168.8).
River otters in the central Platte River select open water over other habitat types, exhibit reduced movements during winter months, and have high annual survival. This information will be used by the Nebraska Game and Parks Commission to assess the status of river otters in Nebraska and direct management efforts for the species.
Advisor: Craig Allen