Southern River Otter Research Articles

Co-Occurrence Between Salmon Farming, Alien American Mink (Neogale vison), and Endangered Otters in Patagonia

The southern river otter (Lontra provocax) and the marine otter (Lontra felina) are endangered species that inhabit Chile. In southern Chile, both species cohabit with the American mink (Neogale vison), an invasive exotic species. The Chilean aquaculture industry has grown exponentially since the late 1980s, with salmon farming taking place from central Chile to the Patagonian fjords and channels. This study assessed co-occurrence between otters, mink, and aquaculture in Patagonia by (1) distributing a survey among workers, fisheries personnel, and aquaculture inspectors concerning observations of otters and mink inside or around aquaculture facilities and outcomes; and (2) a geographical assessment of distribution overlap between known otter territory and salmon farming-registered facilities. We recorded the first anecdotal evidence of interaction, described as co-occurrence, among native otters, American mink, and salmon aquaculture in Patagonia, which varied among seasons and seems to be increasing. We also recorded evidence of difficulty in recognition of the three mustelids among respondents. There is a geographically extended interaction between otters and salmon farms in Chile. The evidence of interaction among alien American mink, native endangered otters, and aquaculture is an early alarm for human–wildlife conflict, and further studies are recommended to ensure native otter conservation.

The otter Lontra Gray, 1843 (Mustelidae, Lutrinae) in the late Pleistocene – early Holocene of Uruguay

Within the order Carnivora, mustelids represent the most diverse family worldwide, with a great ecomorphological diversity in terms of diet, size and locomotory adaptations. Among them, the subfamily Lutrinae corresponds to semiaquatic forms, in which the genus Lontra is included. Widely distributed at present day, this genus is represented by three species across South America (Lontra longicaudis, Lontra felina and Lontra provocax), however their fossil record in the continent is very scarce. In the present contribution, new fossil material assigned to the Neotropical otter Lontra cf. L. longicaudis are described from late Pleistocene – early Holocene (Lujanian Stage/Age) deposits of Uruguay (Sopas and Dolores formations). Based on these findings, some aspects related to the knowledge of the group, paleoecology and paleoenvironmental conditions are discussed.

Variation of local zoological knowledge about Southern river otter and other semi-aquatic mammals in Nahuel Huapi National Park (Argentina)

BackgroundThe huillín (Lontra provocax, Thomas 1908) is an otter, endemic to southern Argentina and Chile. It is in danger of extinction. In the Nahuel Huapi National Park and surroundings is the only freshwater, known and stable population of huillín in Argentina. In this park, several urban and rural centers coexist with this species. The main objective of our work was to answer: How does the local zoological knowledge (LZK) vary about the huillín, particularly its identification and sighting, among people from different social groups, with different ages and gender, who live in the rural or urban environment and with different periods of permanence in the place?MethodsNinety-six written interviews were conducted using visual stimuli to ensure that interviewees refer to the huillín. In addition, we also inquire about the LZK of other species with which it can be confused. Additional open interviews were conducted with participants who observed the huillín to determine the georeferencing of the reported sites and include them on a final map.Results95% of people identified the huillín and this was confused with the coipo in 3% and with the american mink, in 5%. The results show that, in general, the LZK did not vary significantly with the sociocultural characteristics of the participants, showing a remarkable homogeneity. However, people in rural areas are more likely to observe the species than people in urban areas. Moreover, people between 20 and 40 years of age are more likely to observe the huillín. The LZK mapping has identified areas that are consistent with and/or adjacent to official source records. Other areas have also been identified that may provide new information.ConclusionWith this participatory work, we realize that the species is recognized by urban and rural inhabitants and very few confused it. The homogeneity in the LZK found constitutes a kick for the realization of other participatory studies that promote lines of research, action and management that improve the quality of the environments where the only freshwater, known and stable population of the huillín in Argentina lives.

New records of the Endangered southern river otter Lontra provocax, with notes on its diet, in threatened wetlands of southern Chile

AbstractThe wetlands inhabited by the southern river otter Lontra provocax in Chile are subject to anthropogenic disturbances. As a result of the modification and destruction of its habitat, caused by loss of riparian vegetation, and other threats, the species is categorized as Endangered on the IUCN Red List. We monitored the river otter and its diet during September 2020–January 2021 in a swamp forest fragment in southern Chile. We obtained evidence of river otter presence from the upper part of the wetland to the confluence with the Bueno River, suggesting inter-population connectivity of the species in an extensive hydrographic basin. Faeces and food remains showed a predominance of native macrocrustaceans, with introduced fish present at lower levels. The detection of the southern river otter in a fragment of threatened swamp forest suggests a low abundance in environmentally degraded freshwater environments. The identification of subpopulations such as the one reported here provides valuable data to support the conservation of the species in threatened wetlands.

Domestic dog and alien North American mink as reservoirs of infectious diseases in the endangered Southern river otter

Domestic dog and alien North American mink as reservoirs of infectious diseases in the endangered Southern river otter

Surviving despite reduce MHC variation: selection patterns and genetic variation of the endangered Huillín (Lontra provocax)

Surviving despite reduce MHC variation: selection patterns and genetic variation of the endangered Huillín (Lontra provocax)

The southern river otter (<i>Lontra provocax</i>): insights from the perspective of Andean Patagonian ethnozoology

Animals play a significant role in many cultures around the world. The southern river otter Lontra provocax (known locally as the “huillín”) is endemic to southern Argentina and Chile, and is currently in danger of extinction. Mapuche communities have always lived closely alongside their animal resources, generating unique bonds with them. The objective of this work is to obtain an overview of the importance given to this species in the literature of the region with regard to the nature-culture connection. A systematic bibliographical review was carried out using reference libraries and web browsers. From all the sources analysed, 110 were selected which held biocultural information. The main approach used was ecological; however, the ethnohistorical texts provided the richest information on the bond between this otter and humans. The Mapuche name “huillín” appears in all the publications analysed, showing its continuity over time. Of all the zootoponyms found, 87.5% were Chilean and 12.5% were Argentine. The Argentine case is found in Nahuel Huapi lake, and is worthy of note as its name could involve the huillín. The results of this work increase our knowledge of the biocultural heritage of our region, and enable us to reflect on the associated historical and political processes.

Chemical immobilisation of the wild Patagonian otter (Lontra provocax) and the North American mink (Neovison vison)

The Patagonian otter (Lontra provocax) is an endangered species endemic to southern Chile and Argentina. Most of its distribution range has recently been occupied by the American mink (Neovison vison). As part of a long-term study on the impact of mink in Patagonia, we assessed five reversible anaesthetic combination protocols in different doses on wild L. provocax and N. vison, and described the occurrence of any adverse effects. We assessed 16 anaesthetic procedures with a combination of ketamine-medetomidine (KET-MED; 6.0±2.8-0.05±0.01 mg/kg IM, respectively) or ketamine-dexmedetomidine (KET-DEX; 4.1±0.9-0.02±0.004 mg/kg IM) in L. provocax and 23 anaesthetic procedures with KET-MED (13.3±4-0.1±0.04 mg/kg IM), KET-DEX (4.8±0.3-0.024±0.001 mg/kg IM) in a low dose of ketamine (LDK) or KET-DEX (10.2±0.9-0.025±0.002 mg/kg IM) in a high dose of ketamine (HDK) in N. vison. Reversal was accomplished using atipamezole at 5 times the dose of MED or 10 times the dose of DEX. All anaesthetic combinations produced complete immobilisation and rapid anaesthetic induction, except for two otters anaesthetised with KET-MED which exhibited a longer time to initial effect. Hypothermia was commonly observed at the end of the anaesthetic procedures. Due to the hypoxemia presented in four otters at the beginning of anaesthesia, it is recommended to use additional oxygen when possible.

Urban wildlife in times of COVID-19: What can we infer from novel carnivore records in urban areas?

The onset of the COVID-19 pandemic brought an unusual decrease in human activity associated with partial and total lockdowns. Simultaneously, a series of wildlife sightings—mainly in urban areas—have been brought to public attention and often attributed to lockdown measures. Here we report on a series of wild carnivore records, including threatened species, obtained through camera traps set in urban forests, campuses, suburbs, and peri-urban areas of two cities in Chile, during partial lockdown measures. Our records are novel for Chile, a country where urban carnivore ecology is mostly unknown, and include the detection of four native carnivores, including the vulnerable güiña (Leopardus guigna) and the endangered southern river otter (Lontra provocax). These records also constitute a valuable baseline collected during partial lockdown measures in two cities of the Global South. We emphasize, however, that these findings cannot be used to argue for or against an effect of lockdown measures on wildlife. More generally, we call for caution in the interpretation of seemingly novel carnivore records during periods of lockdown and stress the value of international collaboration in evaluating the effects of the Anthropause on wildlife.

More than range exposure: Global otter vulnerability to climate change

Climate change impact on species is commonly assessed by predicting species' range change, a measure of a species' extrinsic exposure. However, this is only one dimension of species' vulnerability to climate change. Spatial arrangement of suitable habitats (e.g., fragmentation), their degree of protection or human disturbance, as well as species' intrinsic sensitivity, such as climatic tolerances, are often neglected. Here, we consider components of species' intrinsic sensitivity to climate change (climatic niche specialization and marginality) together with components of extrinsic exposure (changes in range extent, fragmentation, coverage of protected areas, and human footprint) to develop an integrated vulnerability index to climate change for world's freshwater otters. As top freshwater predators, otters are among the most vulnerable mammals, with most species being threatened by habitat loss and degradation. All dimensions of climate change exposure were based on present and future predictions of species distributions. Annual mean temperature, mean diurnal temperature range, mean temperature of the wettest quarter, precipitation during the wettest quarter, and precipitation seasonality prove the most important variables for otters. All species are vulnerable to climate change, with global vulnerability index ranging from −0.19 for Lontra longicaudis to −36,9 for Aonyx congicus. However, we found that, for a given species, climate change can have both positive and negative effects on different components of extrinsic exposure, and that measures of species' sensitivity are not necessarily congruent with measures of exposure. For instance, the range of all African species would be negatively affected by climate change, but their different sensitivity offers a more (Hydrictis maculicollis, Aonyx capensis) or less (Aonyx congicus) pessimistic perspective on their ability to cope with climate change. Also, highly sensitive species like the South-American Pteronura brasiliensis, Lontra provocax, and Lutra perspicillata might face no exposure to climate change. For the Asian Lutra sumatrana, climate change would instead lead to an increased, less fragmented, and more protected range extent, but the range extent would also be shifted into areas with higher human disturbances. Our study represents a balanced example of how to develop an index aimed at comparatively evaluating vulnerability to climate change of different species by combining different aspects of sensitivity and exposure, providing additional information on which to base more efficient conservation strategies.

Invasive American Mink: Linking Pathogen Risk Between Domestic and Endangered Carnivores

Infectious diseases, in particular canine distemper virus (CDV), are an important threat to the viability of wild carnivore populations. CDV is thought to be transmitted by direct contact between individuals; therefore, the study of species interactions plays a pivotal role in understanding CDV transmission dynamics. However, CDV often appears to move between populations that are ecologically isolated, possibly through bridge hosts that interact with both species. This study investigated how an introduced species could alter multihost interactions and act as a bridge host in a novel carnivore assemblage of domestic dogs (Canis familiaris), invasive American mink (Neovison vison), and threatened river otters (Lontra provocax) in southern Chile. We found that rural dogs interact with mink near farms whereas in riparian habitats, minks and river otters shared the same latrines with both species visiting sites frequently within time intervals well within CDV environmental persistence. No interactions were observed between dogs and otters at either location. Both dog and mink populations were serologically positive for CDV, making the pathogen transfer risk to otters a conservation concern. Altogether, introduced mink in this ecosystem have the potential to act as bridge hosts between domestic dogs and endangered carnivores.

Trophic Segregation of Small Carnivorans (Carnivora: Mustelidae and Mephitidae) from the Southern Cone of South America

Remarkable adaptations in the Carnivora have evolved as a way of dealing with feeding competition, accentuating hypocarnivorous or hypercarnivorous morphotypes. The Carnivora is a highly successful order with 47 living species in South America. Their history in South America is recent, and includes few lineages that arrived before the Panamanian bridge was completed (procyonids), and others that arrived later (felids, mephitids). Here, we evaluated the trophic segregation of small carnivorans (Conepatus chinga, Galictus cuja, Lontra provocax, Lyncodon patagonicus, and the introduced Neovison vison) from southern South America, using a geometric morphometric approach, i.e., Principal Component and Canonical Variate Analysis, to study shape variations and t-tests to study size variation. We also performed Canonical Phylogenetic Ordination to study the association between shape, size, diet, and phylogeny. We identified C. chinga as the most hypocarnivorous member of the guild, G. cuja, L. patagonicus, and N. vison as hypercarnivores, with L. provocax in an intermediate position. Semiaquatic habits segregate Lontra provocax, and partially N. vison, from other species. Significant differences in size were observed between all species pairs, except C. chinga and N. vison. Phylogeny accounts for a very important part of morphological variance, with cladogenetic events between mustelids and mephitids responsible for almost 55 % of it. The small carnivoran guild of southern South America is represented by species adapted to different feeding strategies, with C. chinga and L. provocax preying mainly on invertebrates, G. cuja and L. patagonicus specifically on small vertebrates, and the non-native N. vison with a highly diverse diet.

Trophic interactions of the endangered Southern river otter (Lontra provocax) in a Chilean Ramsar wetland inferred from prey sampling, fecal analysis, and stable isotopes

Non-invasive methodological approaches are highly recommended and commonly used to study the feeding ecology of elusive and threatened mammals. In this study, we use multiple lines of evidence to assess the feeding strategies of the endangered Southern river otter, by determining seasonal prey availability (electrofishing), analysis of undigested prey remains (spraints), and the use of stable isotopes (δ(15)N and δ(13)C) in otter spraints (n = 262) and prey in a wetland ecosystem of southern Chile (39°49'S, 73°15'W). Fecal and isotopic analyses suggest that the otter diet is restricted to a few prey items, particularly the less-mobile, bottom-living, and larger prey such as crayfish (Samastacus spinifrons, 86.11%) and crabs (Aegla spp., 32.45%), supplemented opportunistically by cyprinids (Cyprinus carpio, 9.55%) and catfish (Diplomystes camposensis, 5.66%). The results suggest that the river otter is highly specialized in bottom foraging. Isotopic signatures of food sources and feces revealed a mid-upper trophic position for the Southern river otter, with either higher or lower δ(15)N values than their potential prey items. δ(13)C values for river otters were less enriched than their potential food resources. We suggest that due to their narrow trophic niche and possible dependence on only a few food items, this species may be highly vulnerable to the reduction in its prey populations. Finally, maintaining the ecological interactions between Southern river otters and their prey is considered a central priority for the survival of this endangered carnivore mammal.

Coexistence between the southern river otter and the alien invasive North American mink in marine habitats of southern Chile

AbstractThe interaction between native and introduced predators can be an important determinant of the success of introduced species and of the magnitude of their effects. In Europe, it has been shown that the American mink Neovison vison can be affected by native competitors; however, such evidence has not been found in South America. We studied the southern river otter Lontra provocax and the American mink at five marine sites, where they coexisted, and at one freshwater site, where only mink were present, in southern Chile. We used the signs of both species to study their habitat use and diet, and radio tracking to study their activity patterns. The results indicated that otters and minks tended to use different habitats in marine environments, the otter favouring littoral areas that are rocky and steep while the mink favours areas of gravel with a gently sloping intertidal zone. These differences were also reflected in their diets. At one of the coastal sites where the diet of the two species was similar, the activity pattern of minks was mostly diurnal, which is unusual. While differential habitat use may be the way through which the American mink is able to coexist with the southern river otter in coastal habitats of southern Chile, it is possible that otters are having an effect on individual minks by affecting their activity patterns, although more observations are needed to confirm this hypothesis.

Understanding the inter-specific dynamics of two co-existing predators in the Tierra del Fuego Archipelago: the native southern river otter and the exotic American mink

Knowledge about interactions between endangered native southern river otters (Lontra provocax) and introduced American mink (Neovison vison) is essential for effective management of both species. We evaluated competition for spatial and trophic niches between otter and mink in overlapping and non-overlapping areas, comparing distribution, habitat preference, diet and mink marking behavior. We surveyed otter and mink signs along 250 km of Beagle Channel coastline. Habitat suitability models were constructed based on species presence/absence and habitat characteristics, using generalized linear models. Feces were collected for diet analyses. Otters used forested coasts with 12°–32° shoreline slope and without human influence, and our evidence suggests they were not affected by mink presence. Mink preferred forested and shrubland coasts with 10°–28° shoreline slope. Neither human influence nor otter presence affected mink habitat occupation, but in the presence of otters, mink left fewer signs. Otters consumed more aquatic prey than mink, and mink modified their diet in the presence of otters, consuming more exotic small terrestrial mammals and less fish as well as shifting to smaller and shallower fish species that are less consumed by otters. Mink showed more plastic, generalist behavior than otters, being more tolerant of human presence, using more habitat types and having greater diet breadth. At the same time, otters apparently affect mink adversely and could help limit their invasion in sympatric areas. Conservation and recovery of otters, therefore, may produce a secondary benefit of simultaneously reducing the effect of mink, thereby providing an additional way to control this exotic predator’s population.

A New Microphallid (Digenea) Species from Lontra provocax (Mammalia: Mustelidae) from Freshwater Environments of Northwestern Patagonia (Argentina)

A new microphallid species of Maritrema is described from the native southern river otter, Lontra provocax (Thomas). A naturally infected otter was found dead in the Nahuel Huapi National Park, Argentina. Ovigerous adult worms were recovered from the anterior portion of the intestine. Specimens of Maritrema huillini n. sp. have an unarmed genital pore and glabrous cirrus. They can be distinguished from all other species in the genus by having a long intestinal ceca extending up to three-quarters of the testes length to the level of the posterior border of the testes and a metraterm composed of a proximal sphincter, a non-muscular sac, and a distal muscular portion. This microphallid is the first species recovered from a South American eutherian host and the first digenean recorded for L. provocax.

Phylogeography of the Patagonian otter Lontra provocax: adaptive divergence to marine habitat or signature of southern glacial refugia?

BackgroundA number of studies have described the extension of ice cover in western Patagonia during the Last Glacial Maximum, providing evidence of a complete cover of terrestrial habitat from 41°S to 56°S and two main refugia, one in south-eastern Tierra del Fuego and the other north of the Chiloé Island. However, recent evidence of high genetic diversity in Patagonian river species suggests the existence of aquatic refugia in this region. Here, we further test this hypothesis based on phylogeographic inferences from a semi-aquatic species that is a top predator of river and marine fauna, the huillín or Southern river otter (Lontra provocax).ResultsWe examined mtDNA sequences of the control region, ND5 and Cytochrome-b (2151 bp in total) in 75 samples of L. provocax from 21 locations in river and marine habitats. Phylogenetic analysis illustrates two main divergent clades for L. provocax in continental freshwater habitat. A highly diverse clade was represented by haplotypes from the marine habitat of the Southern Fjords and Channels (SFC) region (43°38' to 53°08'S), whereas only one of these haplotypes was paraphyletic and associated with northern river haplotypes.ConclusionsOur data support the hypothesis of the persistence of L. provocax in western Patagonia, south of the ice sheet limit, during last glacial maximum (41°S latitude). This limit also corresponds to a strong environmental change, which might have spurred L. provocax differentiation between the two environments.

Defining conservation status using limited information: the case of Patagonian otters Lontra provocax in Argentina

The Southern river otter or huillin Lontra provocax has been classified as ‘endangered’, with the loss of riparian forest identified as the main threat to its survival. We used new information on distribution from Argentina to define their status. There are no data on the huillin’s population structure and dynamics, and no estimate of its abundance or population trends at a relevant scale. Our survey teams covered 435 locations in lakes, rivers and coastal sites using a standard and repeatable methodology of 600 m survey transects as adopted for otter surveys across Europe. We found that its present geographic range in Argentina is slightly larger than is characteristic of a species at risk of extinction at the national level, although its contemporary distribution is still radically contracted in comparison to its historical distribution.

Interactions of exotic and native carnivores in an ecotone, the coast of the Beagle Channel, Argentina

In coasts bordering highly productive seas, there can be a flux of resources to the terrestrial ecosystem, and terrestrial carnivores can use marine prey extensively. Two native, endangered species (otter Lontra provocax and culpeo fox Pseudalopex culpaeus lycoides) and two exotic species (mink Neovison vison and grey fox Pseudalopex griseus) inhabit the Beagle coast. The objectives of this paper are: (1) to describe the diet, habitat use and distribution of otters, mink and foxes on the coast of the Beagle channel and (2) to discuss the role of marine resources in the ecological interactions among these species. Diet was determined from the analysis of 245 faeces, and distribution was established from sign surveys. Marine prey occurred in the scats of 98.3, 70.4, 35.5 and 18.2% of otters, mink, culpeo and grey foxes, respectively. Other terrestrial species also use marine resources in Southern Patagonia. All this evidence suggests that the Fueguian coastal channels provide an illuminating example of allochthonous food subsidies from the sea. In the community of four sympatric predators, two native (and endangered) and two exotic, coexistence appears to be facilitated by a renewing marine food subsidy.

Landscape features and crustacean prey as predictors of the Southern river otter distribution in Chile.

AbstractUnderstanding the processes that affect freshwater ecosystems at the watershed level is fundamental for the conservation and management of river otters. During 2 consecutive years, we surveyed the occurrence of the Southern river otter Lontra provocax and its main prey (crustaceans) in a watershed of 9900 km2 in the Chilean temperate forest. We modeled predator and prey distributions with a variety of statistical techniques by relating a set of environmental predictors to species occurrence records. Otter and crustaceans were associated with areas of intermediate to low human disturbance with a mosaic of riparian vegetation densities, mainly at low altitudes. The singularity of the Andean Range, with a very marked elevation gradient and oligotrophic watercourses in the higher areas, created more vulnerable conditions for otter presence because prey abundances were limited in those areas. Human impacts affected otter populations at a landscape scale through the presence of main roads, as these were mostly located in lower parts of the watershed where otters have their primary habitat. These results point to the importance of land management and protection of low‐elevation areas where otters still occur to ensure the long‐term viability of its freshwater populations.