Giant otters … Despite a recent recovery in some areas following banning of the fur trade, the species now faces several emerging threats that remain poorly understood. 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. Reproductive behavior has largely been documented by observations of captive animals. When members of a breeding pair of a similar, young age occupy a high quality territory, they have the potential for high reproductive success: the five most productive breeding pairs (defined as producing 10 or more cubs during their shared breeding tenure) produced at least 10, 11, 19, 21 and 25 cubs within their respective territories. Manu National Park (16,921 km2) lies in the Department of Madre de Dios, south-eastern Peru, at the foothills of the tropical Andes. Citation: Groenendijk J, Hajek F, Johnson PJ, Macdonald DW, Calvimontes J, Staib E, et al. It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. The primary cause for this population decline was poaching for otter pelt. Giant otter population sizes were estimated to illustrate population trends for two different contexts of observed den density representing the pre- and post-filling phases of the reservoir. Overall, the population was comprised of younger individuals in the 2002 and 2004 censuses, compared to 1994 and 1996 censuses, which is consistent with the observed population growth. Since paternity is thought to be known and only the dominant pair in the group breeds, we divided cub production equally between the sexes and calculated ‘mx’ as half the total number of offspring for each parent. The family members clear an area beside a stream for their living quarters, of up to 50 sq meters, usually near feeding sites. Created in 1973, it is a World Heritage Site [30] and is located on the border of the Tropical Andes biodiversity hotspot [31]. For a large top-chain predator that does not live at high population densities, this was an unsupportable harvest rate. have allowed us to estimate the total giant otter population in Manu National Park (including the headwaters) to be between 100 and 130 animals, that is, fewer than 22 groups or breeding pairs (given an average group size of six animals). We present findings on the demography of a population inhabiting the floodplain of Manu National Park, south-eastern Peru, arising from 14 annual dry season censuses over a 16 year period. In parallel with the recovery of some giant otter populations, however, protected areas such as Manu and other giant otter habitats of the Madre de Dios watershed have come under increasing pressure. 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). Entire litters could have been missed from the census if all their members died earlier. Group and territory defence is cooperative [7], [21], though intra-specific agonistic encounters are rarely observed [4], [16], [21] with scent marking at latrines thought to be important for territorial demarcation [4], [16], [18]. 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. Reproductive animals usually remained in their home range until death or disappearance (in 38 of 40 cases). The average age at which philopatric females were first recorded with a litter was 3.89 (n = 9), compared to an average age of 5.25 yrs for non-philopatric females (n = 4). PLoS ONE 9(8): Known throughout much of their range as 'river wolf', they are amongst South America's top carnivores. Additional specific otter observations, film footage and photographic evidence collected between 1987 and 1991 were contributed by Andre Baertschi, and between 2006 and 2009 by Lisa Davenport and the Frankfurt Zoological Society; these 73 extra annual data points allowed us to complete a number of individual giant otter life histories. Habitat fragmentation and loss, as well as pollution are the current major threats to the Giant otter, as the areas where they live are degraded and destroyed by logging, mining and damming. Male giant otters can attain a length of 1.5-1.7m (4.9-5.6ft). They take a nap at mid-day during really warm weather. Each census covered 230 river kilometres and a core group of 20 oxbow lakes (ranging in total surface area from 10.5 to 101.9 hectares, with an average of 36.6 hectares), together with 11 additional lakes which were surveyed less intensively; the census area (number of oxbow lakes and river kilometres) was constant between the three consecutive census teams. The variance in reproductive success thus tended to be higher in males compared to females. The species is also found in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname and Venezuela. We adjusted apparent survival to allow for undetected emigration of transients and groups on the assumption that this was equal to the observed rate of immigration by unknown transients and groups [13] (i.e. One to five latrines for communal use are placed along the perimeter of the site. Giant otters are towards the slow end of the fast-slow continuum in mammal life history strategies explored by Promislow & Harvey [35]. 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. Giant Otter on The IUCN Red List site -, https://en.wikipedia.org/wiki/Giant_otter, http://www.iucnredlist.org/details/18711/0. Pseudo-pregnancies have not been conclusively documented in the wild. The breeding male could be identified by its behaviour, specifically that of intensive marking, and by its year-on-year permanence in the group (non-breeding males do not stay). 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. In two cases, however, dominant females were displaced by another female in the group (a sister and a daughter). A giant otter population is typically described as consisting of family groups and of lone dispersers of both sexes. From the life table (Table 3) we calculated the net reproductive rate Ro (∑lxmx), generation time T (∑xlxmx/Ro) and the intrinsic rate of increase r (ln (Ro)/T) for the Manu population, following Krebs [46] and Creel and Creel [13]. ), and have higher fish capture rates [16]. Giant otter abundance in Manu is characterized by relatively high local densities (5–10 individuals per square kilometre of lake) and low absolute densities (less than 1 individual per 100 square kilometres of rainforest), due to the limited total surface area of suitable aquatic habitats (particularly lakes) and their patchy distribution over the landscape. As one of the few remaining colonization frontiers of the Amazon, the Department of Madre de Dios has seen considerable mining, logging and agricultural expansion over the last two decades. A reproductive individual’s tenure typically ended in disappearance. The giant otter can grow to more than 6 feet (2 meters) long and 70 pounds (32 kg), nearly twice as large as its American counterparts. Year-round, peak in late spring-early summer, 2. Lobo de Rio (the River wolf), Los Lobos del Rio (Wolves of the River), Ariranha. Breeding pair duration and reproductive success. first recorded as cubs in the study area) and estimated-age otters (first recorded as transients or as group members). Unlike many other otter species, sexual dimorphism in giant otters is not pronounced: adult male total body length ranges between 1.5 to 1.8 m, while females are marginally smaller at 1.5 to 1.7 m. Adult males weigh between 23 and 32 kg and females between 20 and 29 kg [4], [7], [19]. Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. Alloparenting includes the feeding of cubs and teaching of hunting skills by sub-adults and adults, and may also occur in the form of ‘babysitting’ in the den [16], [19]. Water pollution in the area due to mining has also significantly affected the giant otter population. ), and average cub productivity (female 6.9, male 6.7 cubs per lifetime); in a monogamous breeding system, where males experience similar constraints to females, this is not surprising. Frankfurt Zoological Society, Frankfurt, Germany, Affiliations In its lower stretches, the Manu is a lowland, white-water river, varying in width between 150 m and 200 m, with sandy beaches and frequent meanders. https://doi.org/10.1371/journal.pone.0106202.g004. Mortality is highest for cubs and for dispersing age classes. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Affiliations These have focused on reducing human pressure on key habitats of the species, with the objective of maintaining habitat quality and maximizing giant otter reproductive success. All field research was conducted in accordance with the requisite permits awarded by the Instituto Nacional de Recursos Naturales (INRENA), later Servicio Nacional de Areas Naturales Protegidas por el Estado (SERNANP). Yes Yes The Giant Otter (Pteronura brasiliensis) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo. Giant Otters are social creatures who learn from each other and live in tight-knit extended families. 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. 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. The giant otter (Pteronura brasiliensis, Zimmermann 1780) is a semi-aquatic carnivore of South America, occurring east of the Andes in the Orinoco, Amazonas, and Parana basins, and in the Guianas [4], [5]. Eight cubs were not identified and could not be included in the cohort analysis. Yes 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. Copyright: © 2014 Groenendijk et al. Male philopatry was not observed. One or two oxbow lakes form the core area or territory within each home range, maintained through defense and/or scent marking activities, and which hold resources critical to ensure successful reproduction. Their fur is extremely soft and is a chocolate brown except for a pattern of large creamy white patches under their long neck, thought to be unique for each individual otter. Cubs of the original pair were invariably adopted by the immigrant males and groups remained stable throughout the transitions, usually producing new litters the following year. As no single protected area in the Madre de Dios region is close to harbouring a demographically viable population (Ne ≥50), interchange of individual otters between the sub-populations is necessary if we are to lower the probability of immediate risk of local extinction in the face of future threats. The giant otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. The social system of giant otters is therefore unusual [15]; a typical giant otter population consists of highly cohesive multi-male/female families with defended territories, plus transients that have left their natal groups on attaining sexual maturity [4], [16], [17]. PLOS ONE promises fair, rigorous peer review, Overall, currently Giant otters are classified as Endangered (EN) and theirs numbers today are decreasing. 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. spend significantly less time obtaining food than do smaller groups (5 inds. This was preceded by national legislation banning commercial hunting in Peru in 1973, coupled with a worldwide decline in the demand for wild pelts. Censuses were coordinated by Staib and Schenck between 1991 and 1996, by Groenendijk and Hajek between 1999 and 2005, and by Calvimontes in 2006. Sub adults and adults in the different resident groups were determined as such with subsequent censuses, as older animals dispersed and cubs identified in previous censuses matured. An adult giant otter may eat 3–4 kg of food per day [7], [16]. Jessica Groenendijk, Frank Hajek, Christof Schenck, Elke Staib, and Jorge Calvimontes would like to thank Peru’s National Service for Protected Areas (SERNANP) for the opportunity to work in Manu National Park. Although widely distributed on a continental scale, overall they may occupy less than 5%, often less than 1% of a given watershed. The new survey indicate again that tourism could have a negative effect on the giant otters. When they visit latrines, otters often defecate and urinate simultaneously [4] (fecaluria). Since the environmental capacity has not increased (the area has been protected since 1973 when the Park was established, almost 20 years before this study was initiated), this suggests a return to carrying capacity after the hunting decades. These individuals probably died, since they were never seen again in the study area. The giant otter, an endangered apex predator in Amazon river ecosystems, was nearly driven to extinction because of demand for its fur. Hence, extrinsic factors such as territory quality and distribution may also limit r and explain why protected giant otter populations in Manu and elsewhere have taken decades to recover from the crash induced by over-hunting. In none of these cases was the male partner related to the philopatric female. They will seek a peaceful place (or "picnic spot") to eat their prey. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. In total, northern La Paz Departmentis estimated to hold around 150 and 200 individuals, representing –together with giant otter populations in neighboring southwestern Pando Department and southeastern Peru- a population stronghold of regional importance for the conservation of this endangered species. The population survivorship curve (Figure 6) includes data from all cohorts censused (N otters = 177, Table S3). At Lake Salvador, where tourism is most intense, we did not observe any offspring this year either - which is an exception among Manu´s otter population. There were about 474 stranded otters in 2016. Post-independence survivorship differed between the sexes (SAS PROC LIFESTEST log-rank χ2 = 5.9, P = 0.015) (Figure 7); this is associated with a marked pulse in male dispersal at age 3.0, resulting in lower male survivorship at this time. The California sea otters grew at an average rate of less than 2 percent per year during the last 10 years. [41] found that total mercury levels in 68% of fish muscles exceeded the tolerable level for the European otter (Lutra lutra) and 17.6% exceeded 0.5 mg kg−1 fresh weight, the common standard for human consumption. The average rate of human population growth between 2002 and 2012 was 3%, the highest in the country [38]. 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, The Manu River was navigated with a 15 m motorised canoe, while oxbow lakes were surveyed with an inflatable boat, following a population census protocol developed by the IUCN/SSC Otter Specialist Group [44]. broad scope, and wide readership – a perfect fit for your research every time. https://doi.org/10.1371/journal.pone.0106202.g007, https://doi.org/10.1371/journal.pone.0106202.g008, https://doi.org/10.1371/journal.pone.0106202.g009. The population of giant otter in the Pantanal may reach 3969 (SD = 1103) individuals, based on our estimated number of individual per kilometer of rivers and creeks (0.54 ± 0.15), over a total of about 7350km of rivers and secondary channels occurring in the Pantanal. A giant otter population is typically described as consisting of family groups and of lone dispersers of both sexes. Giant otters produce 9 different vocalizations and are very loud. 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). Animals were censused towards the end of each age class, i.e., cubs were first censused close to 0.5 years old, after emergence from the den. Some pups in the wild are taken for pets, and usually die because of the inexperience of caretakers. No, Is the Subject Area "Peru" applicable to this article? They stay with the family for 2-3 … However, there are several emerging threats to this sensitive species. The current total population is estimated to be somewhere between 1000-5000 individuals. Inferred animals or groups are those which are assumed to have been in the population and study area in a given year when they were identified in both the previous and subsequent census, and were included in the analyses; in the case of groups for which there was a gap in data continuity, the number of individuals was estimated to be the average of group sizes in the years before and after that gap (provided key group members could be identified). If typical, this suggests a pre census cub mortality of at least 30%. Both their study in Selous and this study in Manu relied on determining age- and sex-specific annual rates of survival rather than mortality: no dead giant otters were encountered during the study hence natural causes of mortality are uncertain. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, In order to determine gender differences in demographic variables, otters were sexed. They do everything together and help each other to hunt food. Gestation is between 64 to 77 days [20], [26], [27], [28]. The IUCN Red List classifies the giant river otter as endangered, with its population still decreasing. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. At the time of censuses, cubs were aged approx. Observed group size ranged from 2 to 13, with a mean of 6.0 (n = 117). begging), sub adults and adults are more difficult to distinguish from each other. At 9-10 months they can hunt independently and look just like their parents. In all cases (n = 11) when vacancies arose for a reproductively dominant female, it was a subordinate female otter from the oldest cohort that inherited the position, though she was not necessarily the only female in that cohort. The Department of Madre de Dios generates 70% of Peru’s artisanal gold production and Peru’s mercury imports have increased exponentially (∼175 t in 2009), 95% of which is used in artisanal gold mining, resulting in the release of large quantities into the atmosphere, sediments and watersheds [40]. We recommend that an aquatic habitat conservation corridor be consolidated along the Madre de Dios River, ensuring the restoration of otter habitats impacted by mining and deforestation therein. km. Giant otters feed almost exclusively on fish [4], [6], [7], [16], [23]. They are seen within the Amazon, Orinoco and La Plata River systems and are found in slow-moving streams and rivers, lakes, swamps, and marshes, as well as flooded forest during the rainy season. In a Manu study analyzing mercury and methyl mercury levels in fish muscles, Gutleb et al. At least 23,162 pelts were officially exported from the Peruvian Amazon during this period [8], with the annual number declining steadily after 1960; the marked reduction in export was likely due to greatly depleted giant otter populations in areas accessible to hunters [9]. White-water lakes are nutrient rich and highly productive; they have considerably higher fish biomass per unit area than their associated river channels - one study reports a fish biomass density of 13.4 g m−2 in these lakes compared with 3.4 in their associated water channels [34]. Breeding males produced a mean of 6.7 cubs per lifetime (SE 1.08). In order to identify individuals and classify them into age categories, we combined field observation of behaviour to establish status (whether cub, juvenile, sub adult, adult, or member of breeding pair), with subsequent review of video footage to establish ID and gender. Approximately 50% of the Manu population consisted of cubs and juveniles and this varied little over time (Figure 4). Gold mining in the area has also been shown to affect giant otters as mercury was found in many of their bloodstreams (mercury is a byproduct of gold mining). Average age of first parturition was 4.4 (n = 14, SE 0.43, range 3.0–9.0). The annual giant otter censuses (recording a maximum of 88 inds.) For more information about PLOS Subject Areas, click 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]. As a norm, the dominant female of a giant otter group produced one litter per year. Discuss the implications of our findings for giant otter conservation in Manu National Park and south-eastern Peru. Territories do not appear to change in size with the seasons, although different microhabitats are used in accordance with fluctuations in water levels. However finding them can sometimes be very challenging. In oxbow lakes, water level fluctuations tend to be less marked (1–3 m), though the strength of the annual floods is highly variable [32]. Rarely, an animal lacked a throat marking (n = 3 out of 294 inds.). Discover a faster, simpler path to publishing in a high-quality journal. 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. All relevant data are within the paper and its Supporting Information files. Of the total of 185 cubs (Table 2), 177 were uniquely identified using their throat markings. Observed litter size at time of census ranged from 1 to 5 with a mode of 2 (post-emergence mean = 2.2, SE = 0.04, n = 78). This species is monogamous, and pairs stay together for life. Other studies [18], [33] suggest that the Madre de Dios River itself, twice as wide as the Manu River, provides the highest quality habitat for the species; its large oxbow lakes and wetlands could support large giant otter groups with high reproductive output and, potentially, the largest sub-population of the watershed. A family has a home range of 12 sq. PJ received support from the Whitley Wildlife Conservation Trust (http://www.wwct.org.uk/) and the John Ellerman Foundation (http://ellerman.org.uk/). Grooming, resting and communicating the 1960s, 20,000 pelts were exported from Brazil were and. From known-age individuals were entirely out of the Manu river flood plain a litter usually... 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