Explore the vast range of titles available.

River otter (Lontra canadensis) predation of seabirds has been periodically documented throughout North America, but most knowledge about this subject exists as anecdotal observations in the memories of experienced seabird biologists. Using surveys, interviews, white papers, and published literature, we collected detailed records of seabird predation by river otters at 73 islands on the coasts of North America. From this dataset, we were able to draw conclusions about the seabird species experiencing river otter predation, the geographic distribution of predation records, and factors associated with river otter occurrence at colony islands. River otters preferentially select for small‐bodied burrow‐nesting species, with predation of ground‐nesting species occurring mostly opportunistically. Predation of nesting seabirds occurs across the entire Pacific range of the river otter and throughout the northern Atlantic, but we did not locate a single record of this behavior on the Atlantic coast south of Maine; we hypothesize that this is due to geographic differences in nesting seabird assemblages. The presence of burrow‐nesting seabirds and proximity to the mainland are both strong predictors of river otter occurrence at colony islands. River otters will swim up to eight kilometers across open ocean to access seabird colonies, but predation is significantly more common at nearshore islands (median distance of 1.7 km). Reports of seabird predation by river otters in published literature are rare, are heavily biased toward an ornithological audience, and have decreased over time as “Field Notes” style publications have decreased in popularity. Despite being more widespread than previously reported, predation by river otters appears to be sustainable for most colony nesting seabird populations. Northern river otter predation of nesting seabirds is rarely reported in published literature, but this behavior is common throughout the Pacific coast and on the northern Atlantic coast. Through surveys of seabird field biologists, we documented records of river otters hunting eighteen different species of nesting seabirds at 73 different colony islands in the United States and Canada. River otters show a selective preference for small‐bodied burrow‐nesting seabird species, with predation of larger surface‐nesters occurring mostly opportunistically.

Understanding habitat use in sympatric species is key to informing conservation efforts. Lontra felina and L. provocax are semi-aquatic mustelids commonly known as South American marine and southern river otters, respectively, that occupy contrasting coastal environments in southern Chile. We investigated habitat characteristics associated with sightings of both species in the Raúl Marín Balmaceda Multiple Use Protected Area, northern Chilean Patagonia. Our results show L. felina is restricted to exposed, steep rocky shores with sparse vegetation and intertidal belts dominated by Durvillaea antarctica and Lessonia spp., while L. provocax was found to be associated with sheltered, forested margins and estuarine areas dominated by Macrocystis pyrifera and other meadow-forming algae. Records did not show coexistence of both species in the same location; therefore, it is concluded that they exhibit a sympatric but non-syntopic pattern.

River otters (Lontra canadensis) are apex predators that bioaccumulate contaminants via their diet, potentially serving as biomonitors of watershed health. They reside throughout the Green-Duwamish River, WA (USA), a watershed encompassing an extreme urbanization gradient, including a US Superfund site slated for a 17-year remediation. The objectives of this study were to document baseline contaminant levels in river otters, assess otters’ utility as top trophic-level biomonitors of contaminant exposure, and evaluate the potential for health impacts on this species. We measured a suite of contaminants of concern, lipid content, nitrogen stable isotopes (δ15N), and microsatellite DNA markers in 69 otter scat samples collected from twelve sites. Landcover characteristics were used to group sampling sites into industrial (Superfund site), suburban, and rural development zones. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ether flame-retardants (PBDEs), dichlorodiphenyl-trichloroethane and its metabolites (DDTs), and polycyclic aromatic hydrocarbons (PAHs) increased significantly with increasing urbanization, and were best predicted by models that included development zone, suggesting that river otters are effective biomonitors, as defined in this study. Diet also played an important role, with lipid content, δ15N or both included in all best models. We recommend river otter scat be included in evaluating restoration efforts in this Superfund site, and as a potentially useful monitoring tool wherever otters are found. We also report ΣPCB and ΣPAH exposures among the highest published for wild river otters, with almost 70% of samples in the Superfund site exceeding established levels of concern.

The North American river otter Lontra canadensis is a semi‐aquatic furbearer species that historically ranged throughout North America. Starting in the mid‐1800s and continuing through the early 1900s, the negative effects associated with anthropogenic disturbances (i.e. overharvest, development and ultimately habitat alternation) led to local extinctions. Researchers debate whether current land use patterns are affecting river otter occupancy. New Jersey is the most densely populated state in the United States, thus it provides a perfect study area to test potential anthropogenic effects on river otters. Using occupancy modeling to examine river otter habitat preferences, we measured presence/absence at 244 low order streams from January–April 2011–2012 along with 19 corresponding site/landscape covariates in both northern and southern New Jersey. In southern New Jersey, we detected otters at 83/141 sites (58.9%) with a detection probability of 97.7% across repeat visits and a predicted occupancy of 59.4 ± 0.04%. In northern New Jersey we detected otters at 31/103 sites (30.1%) with a detection probability of 44.5% across repeat visits and a predicted occupancy of 58.8 ± 0.04%. We determined the influence of habitat covariates on otter occupancy and found that water depth, water quality, stream width and mink presence were positively correlated with otter occupancy. The % commercial, industrial, transportation and recreational habitat, % low intensity development, bank slope, and distance to lake were negatively correlated with otter occupancy. Knowing the location of occupied stream and latrine sites will assist biologists in their efforts to monitor river otter populations and help estimate river otter density for harvest and conservation efforts.

IntroductionSmall marine carnivores inhabiting fragmented rocky coastlines are increasingly exposed to anthropogenic pressures, yet mortality drivers in these systems remain poorly quantified.MethodsWe analyzed 22 years of carcass records (2003–2024) and standardized necropsies to evaluate the contribution of anthropogenic causes and their spatial and temporal patterns in marine otters (Lontra felina) from north-central Chile.ResultsWe documented 173 mortality events involving 181 individuals. Space–time permutation analyses revealed three significant peri-urban clusters associated with areas of high human activity. Among cases with assigned cause, anthropogenic drivers predominated, particularly free-ranging dog attacks, followed by fisheries bycatch and non-specific trauma. Although seasonal differences were not statistically significant, anthropogenic mortality contributed proportionally more during summer months.DiscussionOur findings highlight terrestrial human-related pressures, particularly free-ranging dogs, as underrecognized mortality pathways in marine otters inhabiting human-dominated coastlines. Recurrent spatial clustering indicates predictable mortality risk hotspots and demonstrates the utility of spatio-temporal approaches for informing conservation and management strategies integrating terrestrial and marine systems.

We evaluated the biogeographic factors that influence composition and diversity of the Neotropical otter diet. We also tested whether Lontra longicaudis selected fish in its diet per their availability. We collected data from 41 studies, covering most of the otter’s distribution, 32 of which had prey identified to family level. Fish was the main prey for L. longicaudis throughout the species range. However, its frequency was higher in sites farther from the coast and at higher slopes. Alternative prey items compensate the decrease in fish. Temperature seasonality, slope, and distance to coast were the most important factors determining the diversity of the otter’s diet. Populations in areas with more variation in temperature and/or closer to the coast showed a more diverse diet with an increase of alternative prey. Trophic diversity was positively correlated with temperature seasonality but negatively correlated with the slope and distance to coast. As an opportunist, semiaquatic predator with a wide distribution range, L. longicaudis has a flexible diet, and this plasticity might be explained by the wide range of habitats occupied by otters. Furthermore, Neotropical otter diet was also found to be more similar in geographically closer areas, as well as in similar environment types.

Niche partitioning occurs among coexisting populations to reduce the effects of competitive exclusion among species of similar niche. The aim of the present study is to verify the trophic niche partitioning and feeding behavior between two mustelids, the Giant otter and the Neotropical otter, through the dry and rainy season hydrologic of the Lower Xingu River. Our results suggest that the diets of both mustelids are composed primarily of fish of the family Anostomidae (Headstanders). Despite extensive niche overlap, our results indicate partitioning is facilitated by differences in niche breadth, with potential implications for conservation of both species in the case of declines in prey abundance and diversity. Both species inhabit an area recently impacted by completion of the Belo Monte Hydropower Plant, resulting in large changes to the hydrologic regime. Thus, our results provide important information for conservation efforts regarding the feeding behavior and co-occurrence of both species, as well as providing a baseline for monitoring future health of these mustelid populations. The present study is the first to test the hypothesis of niche partitioning between these two mustelids outside a protected area in the Amazon.

Effects of climate change on animal behavior and cascading ecosystem responses are rarely evaluated. In coastal Alaska, social river otters (Lontra Canadensis), largely males, cooperatively forage on schooling fish and use latrine sites to communicate group associations and dominance. Conversely, solitary otters, mainly females, feed on intertidal-demersal fish and display mutual avoidance via scent marking. This behavioral variability creates \"hotspots\" of nutrient deposition and affects plant productivity and diversity on the terrestrial landscape. Because the abundance of schooling pelagic fish is predicted to decline with climate change, we developed a spatially-explicit individual-based model (IBM) of otter behavior and tested six scenarios based on potential shifts to distribution patterns of schooling fish. Emergent patterns from the IBM closely mimicked observed otter behavior and landscape use in the absence of explicit rules of intraspecific attraction or repulsion. Model results were most sensitive to rules regarding spatial memory and activity state following an encounter with a fish school. With declining availability of schooling fish, the number of social groups and the time simulated otters spent in the company of conspecifics declined. Concurrently, model results suggested an elevation of defecation rate, a 25% increase in nitrogen transport to the terrestrial landscape, and significant changes to the spatial distribution of \"hotspots\" with declines in schooling fish availability. However, reductions in availability of schooling fish could lead to declines in otter density over time.

The southern river otter (Lontra provocax) and the marine otter (Lontra felina) are endangered species . Southern river otters inhabit rivers, streams, lakes, and fjords. Current populations in rivers and lakes have been confirmed only in a few isolated areas between 39... and 44... S . However, their distribution along the Chiloe Archipelago, marine fjords, and channels remains poorly understood. The marine otter lives along the Pacific Ocean coast from 6... S in northern Peru to 56... S near Cape Horn, Chile (Valqui, 2012). Their habitat is primarily described as rocky and exposed to the wind and sea waves of the Pacific Ocean (Valqui, 2012). From Tacna in southern Peru to the border with Chile and Chiloe Island, the shoreline alternates between rocky patches and discontinuous sandy beaches (Medina-Vogel et al., 2008; Valqui, 2012). Geographically, rocky shoreline patches become increasingly separated from northern to central southern Chile, with otter occupancy significantly influenced by human presence along the exposed coastline (Medina-Vogel et al., 2008).