Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 48-49).

After steep declines due to overharvest and habitat loss, North American river otter (Lontra canadensis) populations have been increasing in most of the U.S. Radiotelemetry is an essential tool for understanding river otter habitat use, survival rates, and sources of mortality, which is important for successfully managing these growing populations. Surgically implanting radiotransmitters is standard for river otters, but strict requirements for the handling and transport of DEA-scheduled drugs for sedation, and the lack of accessible surgery suites, can limit researchers. My objectives were to: (1) develop a non-scheduled drug combination to sedate river otters and surgically implant intra-abdominal transmitters in a field setting, (2) determine survival rates and causes of mortality for river otters, and (3) quantify fourth order habitat selection at river otter daytime resting sites. During 2018-2020, I surgically implanted 24 river otters with transmitters in southern Illinois and monitored them via radiotelemetry to determine survival and causes of mortality. The effectiveness of the drug combination of Dexmedetomidine and Nalbuphine for chemically immobilizing river otters was tested to determine the appropriate dosage. I used homing to track river otters to 132 daytime resting sites where I described the structure used, closest water type, and distance to water; for 51 of these resting sites I also measured understory cover, overstory cover, distance to water, and presence of river otter and beaver sign. These 51 sites were paired with 1-4 random riparian locations, where I measured the same habitat variables. I then modeled habitat selection of daytime resting sites using conditional logistic regression. A combination of 0.06 mg dexmedetomidine/kg and 1.2 mg nalbuphine/kg injected intramuscularly followed by a 10-15 min induction period was sufficient to chemically immobilize river otters enough for further sedation with 1-4% isoflurane gas. Surgery in the field was successful, with only 2 sedation-related mortalities recorded. Estimated river otter survival was 0.84 ± 0.09 with no difference between males (0.83 ± 0.11) and females (0.86 ± 0.13) ( = 0, P = 0.900) and or between protected areas (0.80 ± 0.10) and harvested areas (0.83 ± 0.15) ( = 0.3, P = 0.600). Four river otters died (2 harvest, 2 unknown causes) during my study. Daytime rest sites were located in non-enclosed vegetation (n = 54) as well as enclosed sites, such as bank dens (n = 39), beaver lodges (n = 33), and wood piles (n = 6). River otters selected for greater understory cover at all sites, though enclosed sites had less understory cover than non-enclosed sites (all P ≤ 0.001). The top habitat selection model included the parameters understory cover and the beaver sign but did not include canopy cover. My study offers a novel way to sedate river otters without DEA-scheduled drugs, updates information about river otter survival, and provides new information on fourth order habitat selection at daytime resting sites.

Polycyclic aromatic compounds (PACs) are a group of chemicals encompassing thousands of different aromatic, alkyl aromatic and heterocyclic hydrocarbons (i.e.- containing N, S, or O- atoms); 16 of which have been designated as priority pollutants due to their toxicity and prevalence. Several studies have highlighted increases in the concentrations of C1-C4 alkylated PACs and heterocyclic aromatic hydrocarbons such as dibenzothiophenes in the atmosphere, water, soil and sediments, plants, wildlife and fish in the Athabasca Oil Sands Region (AOSR). Although there has been considerable research attention related to the toxic, carcinogenic and mutagenic properties of PACs, there is an increasing awareness that these chemicals may also have profound endocrine disrupting properties in wildlife. North American river otter (Lontra canadensis) are good indicators of ecosystem health due to their ecology and sensitivity to environmental pollutants. In this thesis, we first demonstrated the utility of adopting paleotoxicological frameworks in defining environmental baseline levels of PACs and likely biological effects from exposure to these complex environmental mixtures. These methods allowed us to reconstruct historical PAC deposition patterns to impacted areas while simultaneously determining likely biological effects such as endocrine disruption. Next, we showed how PACs exhibited trophic dilution in a Boreal food chain dominated by river otters. Snails, prey and predator fish, as well as river otters were collected from four main study areas in the AOSR in northeastern Alberta, Canada. Bioaccumulation factors such as biota-sediment accumulation factors (BSAF) and trophic magnification factors (TMF) were used to evaluate the partitioning behavior of PACs in the environment and subsequent risks to biota. Our results revealed localized enrichment of certain PACs and subsequent metabolism in higher order vertebrates. Finally, we successfully combined ecotoxicological and physiological analyses paired with population genetic estimates to investigate endocrine disruption and population-level responses to exposure to PACs. River otters are known for their habitual use of latrine sites. Latrine sites represent a unique opportunity for biomonitoring programs to study river otters using indirect sampling methods. In this thesis, PACs were characterized and evaluated in sediment, lower and higher trophic biota with demonstrated impacts on endocrine processes and river otter population health. Effects-based assessments such as the ones presented in this thesis are more powerful for environmental monitoring programs than stressor-based assessment methods (such as describing presence/absence or levels of contaminants) as they provide greater biological context to monitoring data. In turn, these are helpful in selecting triggers for environmental effects monitoring or adaptive management programs.

Master of Science / Department of Biology / Craig Paukert / The North American river otter (Lontra canadensis) was extirpated throughout much of its range but is now recovering in many areas. Consequently, there is a need to determine river otter occupancy and habitat associations. We conducted sign surveys from January to April 2008 and 2009 in eastern Kansas to assess how local- and landscape-scale habitat affects river otter occupancy and how survey methods and habitat affect the detectability of river otter sign. Multiple observers surveyed 3-9 400-m stretches of stream and reservoir shorelines for 110 randomly-selected sites and measured local-scale (within a 100 m buffer of site) habitat variables (e.g., stream order, sinuosity, proportion of land cover types) and landscape-scale (Hydrological Unit Code 14 watershed) habitat variables (e.g., road density, shoreline diversity, proportion of land cover types). We then modeled occupancy and detection probability as a function of these covariates using Program PRESENCE. The overall probability of occupancy accounting for detection probability was 0.329. The best-fitting model indicated river otter occupancy increased with the proportion of woodland cover and decreased with the proportion of cropland and grassland cover at the local scale. The best-fitting model also indicated occupancy increased with decreased shoreline diversity, waterbody density, and stream density at the landscape scale, possibly because of the influence of large reservoirs in the watershed. Occupancy was not affected by land cover or human disturbance at the landscape scale, perhaps due to our relatively homogeneous study area or because river otters are habitat generalists. Detection probability for 400-m surveys was highest in mud substrates (p = 0.600) and lowest in snow (p = 0.180) and litter substrates (p = 0.267). Detection probability for scat was more than double that for tracks, and detection probabilities were 17-64% lower for novice observers than experienced observers. Detection probability also increased with survey length. Sign surveys are a useful technique for monitoring many species, including river otters, and accounting for detection probability will improve estimation of occupancy. Furthermore, understanding the ecological factors and the scale important to river otter occurrence will be useful in identifying areas for restoration and management efforts.

Social behavior and habitat selection of river otters (Lontra canadensis) are highly variable among populations and there is limited information on how space use of this mustelid changes in human-modified environments. Understanding the spatial ecology of river otters is important for efforts focused on habitat management and preventing human-wildlife conflicts. My objectives were to quantify: (1) home ranges and core areas, (2) second- and third-order habitat selection, and (3) relationships between home-range size and intensity of human development for river otters in southern Illinois. VHF transmitters were used to track river otters during 2014-2016. Home-range and core-area sizes then were compared between males (n = 8) and females (n = 10), as was home-range overlap. I also compared the frequency individuals were located <25 m from a conspecific between sexes. Habitat selection at the second and third orders was analyzed with an eigen-analysis of selection ratios. Male river otters had larger home ranges and core areas than females. Home ranges of males overlapped frequently; lack of core-area overlap among females suggested they may be territorial. Males also were located <25 m from a conspecific more frequently than females (P = 0.023), and male-male dyads shared space more than male-female and female-female dyads (P = 0.002). Herbaceous and wooded wetlands were most strongly selected for at both second- and third-order scales, but streams and ponds also were selected. Regarding terrestrial cover types, river otters selected land with vegetative cover over areas with impervious surface (e.g., parking lots and shopping centers). Forests were selected over crop fields at the third-order, but not second-order, scale. Use of urbanized land was uncommon for river otters, and there was a positive relationship (P = 0.004) between home-range size and the percentage of home range within developed open space (e.g., roads and residential lawns). The habitat selection and sociality of river otters in southern Illinois varied among individuals, as it does among river otter populations throughout North America. By recording sex differences in social behavior and selection of aquatic and upland habitat, my study provides wildlife biologists with a better understanding of river otter space use throughout a rural-urban gradient.

In order to analyze the bacterial community of river otter scat (fecal material) at the class level, river otter scat samples were collected from Grizzly Island Wildlife Area (Solano County, CA) and the Cosumnes River Preserve (Sacramento County, CA). DNA was isolated from each sample with the MOBIO PowerSoil™ DNA Isolation Kit and 16S rRNA gene sequences were amplified from each sample. After digestion with Mspl, TRFLPs were analyzed in an ABI Prism™ 310 Genetic Analyzetin triplicate and data peak information from each electropherogram was uploaded into the Phylogenetic Assignment Tool (PAT). Species belonging to the Class Bacilli were the most abundant followed by unclassified species. Two road killed river otters were necropsied to recover brain and blood tissue. DNA was isolated using the Qiagen Tissue DNeasy Kit. Samples from both otters were amplified with a singe tube nested PCR primer set for the detection of the ITS 1 region of Toxoplasma gondii. Scat samples used in the T-RFLP analysis were also tested for the presence ofT. gondii using the same nested primer set. Neither the river otter tissue samples nor any of the scat samples used in this analysis showed evidence of infeGtion with T. gondii.

The northern river otter (Lontra canadensis) is a semi-aquatic carnivore whose range extends throughout most of the United States and Canada. The northern river otter experienced a severe range contraction post-European settlement, but due to widespread management has in recent decades begun to recover much of its former range and habitat. We translocated 27 river otters from Utah and Idaho to the Provo River, Utah from November 2009 through January 2012 in a reintroduction effort to restore the northern river otter to its native range. Of these 27 otters, 6 died as a result of effects related to the translocation. We used linear regression and model selection to determine what factors had the most influence on the immediate mortality of translocated otters. We found that body mass was the most important factor, followed by sex. Indeed, otters at the high end of the body mass spectrum were 4 times more likely to survive a translocation than otters at the low end of body mass. Along with the reintroduction project, we determined the food habits of the northern river otter in the Provo River watershed. We located and monitored otter latrine sites from February 2010 through February 2012, collecting scats on a monthly basis. We identified prey items in otter scat and recorded data as the frequency of prey items per total number of scats, presented as a percentage. Fish was the primary class of prey taken by otters (96.5%), followed by crustaceans (16.9%). Otter diet varied among seasons for nearly all classes (G = 127.8, d. f. = 24, P < 0.001) and families (G = 132.94, d. f. = 18, P < 0.001) of prey. We conclude that otters are potentially selecting prey in the main channel according to their abundance and in inverse proportion to their swimming ability. However, with multiple habitat types that vary in species richness and diversity, it was difficult to determine which prey items otters are selecting for without direct behavioral data on location of foraging. We examined the diet of the northern river otter at the regional and continental scale. We examined 100 publications and 106 prey lists in order to determine the food habits of the northern river otter among ecoregions and seasons. Fish was found to occur in otter diet more often than any other class of prey, followed by malacostracans. At the family level, Astacoidea contributed more to otter diet than any other family of prey. Multiple classes and families varied by ecoregion and/or by season. Crayfish, while not the primary component of otter prey throughout North America, was found to be the primary component when readily available. Furthermore, we developed a model of river otter prey selection which includes factors that may have an impact on the availability of prey to otters. Otter prey selection is likely due to a variety of factors, including the habitat, detectability, catchability, and palatability of prey.

Indirect signs of species presence (e.g., tracks, scats, hairs) are frequently used to detect target species in occupancy, presence/absence, and other wildlife studies. Indirect signs are often more efficient than direct observation of elusive animals, making such signs well suited for long-term and broad-scale monitoring programs. However, error associated with misidentification of indirect signs can be high, and should be measured if meaningful inferences about population parameters are to be made. This study addressed the need for systematic approaches to estimate and minimize variation due to observer error in identifying indirect signs. I reanalyzed data from 4 replicates of a presence/absence survey of northern river otters (Lontra canadensis) that had been conducted by Texas Parks and Wildlife Department (1996-2003). Sixteen observers had recorded tracks at sample points under bridges (n = 250) distributed throughout 27 counties in the Piney-Woods ecoregion of east Texas. My objectives were to 1) determine if observers were a source of bias in the survey, 2) estimate the proportion of error associated with track identification skill, and 3) evaluate the use of an international certification procedure that measured observer tracking skill. The null hypothesis that observers had no effect on the variation in reported sign was rejected. Indeed, binary logistic regression tests indicated that observers were significantly associated with variation in reported track presence. Observers were not randomly distributed among bridge sites, and therefore were significantly correlated with 4 habitat variables that may have influenced heterogeneity in otter occupancy and probability of detection (watershed, vegetation-type, water-type, bridge-area). On average, experienced observers (n = 7) misidentified 44% of otter tracks, with a range of 0% to 100% correct detection. Also, 13% of the tracks of species determined to be 'otter-like' were misidentified as belonging to an otter. During the certification procedure, participants misidentified the tracks of 12 species as otter. Inaccurate identification of indirect signs is a likely source of error in wildlife studies. I recommend that observer skill in identification of indirect signs be measured in order to detect and control for observer bias in wildlife monitoring.

No description available.

The conducted study on the southern river otter Lontra provocax presents for the first time substantial data and analyses on preferred habitat components, activity pattern, prey availability, diet composition and potential food competitors, as well as a first attempt in age determination. Three southern river otter (1,2) were successfully equipped with radio transmitter. Both females were classified as resident whereas the male southern river otter was classified as temporary resident. Home range (FK 95) was 14358 m and 17675 m respectively. As only one home range was accessible for habitat analysis, the preferred habitat structures were analysed. Thus the plant Chusquea quila is most important for den sites in anthropogenic modified areas. In natural habitat dens were encountered under big trees and overhanging roots. Hunting areas in anthropogenic modified regions show considerably more woody debris than non-hunting areas, as the main prey the crayfish Samastacus spinifrons hides in this substrate. Most of their time southern river otter spent in their dens (60 %). Lontra provocax show cathemeral behaviour and when being active, the time bouts of movement behaviour averaged 2:18 hours.The crustacean species Samastacus spinifrons was the most encountered aquatic prey species in abundance and in total biomass in the river Queule and in the diet of Lontra provocax. Likewise fish may play an important role to meet the southern river otter s daily metabolic requirements. Monthly collected water samples even close to villages, had physico-chemical parameter values well below critical or toxic levels on aquatic species. Age determination was conducted on four male skulls of southern river otter. Tooth wears; tooth abrasions; dental pulp; relative width of dental pulp, incremental cementum lines and sutures of the skull were used for age determination. The animals were classified as juvenile (1), subadult-adult (1) and senior (2).