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As the lakes are all formed by the Manu River, lake depth is not highly variable; average lake depth is 2.04 m (range 0.5–4.89 m, SD = 0.97, n = 22) [33]. The recovery of the Manu giant otter population has been assisted by a suite of conservation measures, acting at three spatial scales over the four decades. A family consists of a mated pair and their offspring of several generation. By age of dispersal, approximately 50% of offspring have died. These are the longest recorded ages for free ranging giant otters. begging), sub adults and adults are more difficult to distinguish from each other. Inferred census totals ranged from 42 individuals in 1994 to 88 individuals in 2004 (Table 2). Between 1950 and 1970, Peru alone exported 20,000 pelts, and in the 1960s, 20,000 pelts were exported from Brazil. Of 41 reproductively mature females, 11 (27%) were not recorded to produce a single litter, 17 (41%) produced only one or two litters, and 13 (32%) produced three litters or more. Successors were trained in census methodology in the field by the preceding census team, and the same field equipment was used. Overlapping of neighbouring home ranges was not observed in Manu, but cannot be discounted. Funding: ES and CS received support from the Munich Wildlife Society as well as two doctorate grants from the Gottlieb Daimler and Karl Benz Foundation. Females are smaller at 1-1.5m (3.3-4.9ft). The IUCN Red List has no current estimate for the total Giant otter population. At 9-10 months they can hunt independently and look just like their parents. It is also known as the Guiana flat-tailed otter, margin-tailed otter and winged-tailed otter. For more information about PLOS Subject Areas, click The giant otter (Pteronura brasiliensis) is an Endangered apex carnivore inhabiting the Madre de Dios region in Peru’s Amazon basin. Observations of captive individuals suggest that giant otters of both sexes reach sexual maturity at between 2 and 3 years of age [20], [22]. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Of the total of 185 cubs (Table 2), 177 were uniquely identified using their throat markings. The average reproductive lifespan for adult males was 5.2 (n = 31, SE 0.49, range 1.0–13.0), with 3.0 also being the earliest age at which males fathered their first recorded litter. Persecution, degradation of the jaguar's habitat, and decrease in its prey are thought to have reduced the species population to less than 50,000 mature breeding individuals in the wild. the Manu floodplain is assumed to be neither a source nor sink population within the wider Upper Madre de Dios river ecosystem). The most important economic activity by far is alluvial gold mining, more than half of it informal and illegal. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, Affiliations As a consequence, many individuals, particularly transients, could not be sexed until 2002, when we discovered a simple and effective method of sexing giant otters, regardless of age. Unfortunately, due to habitat destruction from logging, farming, and mining, the Giant Otter is near extinction, with a wild population … Both displaced females stayed on in their groups until disappearance, one for a further two years. The IUCN Red List has no current estimate for the total Giant otter population. Females start dispersing as young as 1 year old but may stay on in their natal territories up to two years longer than males (6.5 years). In order to develop survivorship and fecundity schedules and a population life table, we carried out a cohort analysis [46] with 177 known-age individuals whose life histories were known from birth to disappearance. Observations of wild and captive otters suggest that giant otters are weaned at approx. Evergreen tropical forest dominates the Manu River flood plain. The threats they face are numerous, and include habitat destruction, hunting for pelts, and conflict with fisherman, who often see the otter a… Its jaws and teeth are so powerful, that it can literally bite through the shell of a turtle. The California sea otters grew at an average rate of less than 2 percent per year during the last 10 years. The Giant otter, living in South America, and the largest of the otters in its total length, is the cousin of the sea and river otters in North America, Europe and Africa. Partner compatibility (i.e. Gestation lasts 65-70 days and the altricial young are born in late August until early October. Of 50 reproductively mature males, 19 (38%) were not recorded to produce a single litter, 16 (32%) produced only one or two litters, and 15 (30%) produced three litters or more. Delayed implantation, suggested by Sykes-Gatz [20] for giant otters in captivity, was confirmed by Corredor and Muñoz [29] at Cali Zoo. Nature Services Peru, Department of Cusco, Cusco, Perú, 6 months old [17], [20] and rely to a great extent on other group members for prey provision until 1.5 years old [16]. The Giant otter was discovered by Gmelin in 1788. Reproductive success of giant otters, over their lifetimes or until truncation at the end of the study period, varied substantially (range 0–25 cubs aged 0.5 years). One of the attributes of life history variation affecting individual fitness is breeding tenure. The current total population is estimated to be somewhere between 1000-5000 individuals. This is explained by a combination of factors: (1) physiological traits such as late age at first reproduction and long generation time, (2) a high degree of reproductive skew, (3) small litters produced only once a year, and (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Finally, regional and local habitat management measures such as Protected Area zoning and oxbow lake management plans have been implemented in Madre de Dios since 1990 [18]. Thus, there has been a painfully gradual increase in the population of southern sea otters and according to a 2017 counting, these otters are numbered around 3,186. Data from known-age individuals were used to assign ages to the estimated-age animals. We observed four groups moving litters of young cubs between dens, estimated at between two weeks and one month old. Frankfurt Zoological Society, Frankfurt, Germany, Affiliation There were about 474 stranded otters in 2016. Animals that were seen in 1996 and again in 1999 were inferred for the intermediate years. https://doi.org/10.1371/journal.pone.0106202.g006. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Where more than one subordinate female was present in the oldest cohort, we could not determine the factor(s) that influenced which of the siblings became dominant. We used both male and female offspring because many cubs could not be sexed. The aquatic systems, their floodplains, and forests associated with these, are thus amongst the most threatened habitats in Madre de Dios, both due to their natural limited extent, as well as the concentration of human activities such as mining and agriculture in these areas [42]. The Giant River Otter only lives in three river systems: the Am… The Balbina dam created ∼3525 islands and increased the open-water surface and total reservoir perimeter available to otters by a factor of 62.7 and 8.9, respectively. Giant Otters (Pteronura brasiliensis) were on the brink of extinction with an estimate of just 300 individuals left in the wild in the 1980s, according to an IUCN report. Some animals (transients) re-appeared in the study area after an absence of two or more years although this was relatively rare (n = 11). It appears, retrospectively, that the population in the floodplain of Manu National Park was still in a process of recovery from the impact of the pelt trade - not all the available territories were occupied when this study was initiated in 1991. Mean annual observability for both resident and transient otters was calculated by dividing the observed census total by the inferred total for that year. Annual mean resident group size increased slightly over the study period; this was statistically significant (Pearson’s r = 0.56, P = 0.03) (Figure 3). Under field conditions, body size is not a reliable indicator of gender or age; some males were noticeably smaller than their partners and older animals were not always the largest [16]. Observed group size ranged from 2 to 13, with a mean of 6.0 (n = 117). Driven by increasing gold prices and new road access, the extent of gold mining in the Madre de Dios region increased from less than 10,000 hectares in 1999 to more than 50,000 hectares in 2012. following the predecessor’s death). As the river current erodes the bank, some meanders are cut off to form oxbow lakes, which can persist as distinct bodies of water for decades or centuries, but which remain connected to the parent river to varying degrees [32]. Sizeable burrows are then built under fallen logs. These animals are most active from 10-11 am and from 3-5 pm. We studied population structure and genetic diversity of giant otters from Colombia’s Orinoco basin using analyses of … Thus, the combination of (1) physiological traits such as late age at first reproduction and long generation time, (2) a high degree of reproductive skew, (3) small litters produced only once a year and a pre-census cub mortality of 30%, (4) a further 50% mortality up to age of dispersal as well as high mortality amongst dispersers (especially males), (5) plus the influence of breeding pair compatibility, all help to explain the low intrinsic rate of increase of the population, slowing its ability to recover from the pelt trade in the past or possible future disease outbreaks. Affiliations Citation: Groenendijk J, Hajek F, Johnson PJ, Macdonald DW, Calvimontes J, Staib E, et al. 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