Strolling from their dwelling down to the river, the parents supervise as older siblings play with the youngsters, frolicking in the water and on the banks. 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. 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]. Analyzed the data: JS FH PJ. 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]. This species is monogamous, and pairs stay together for life. We compared changes in habitat area and estimated giant otter population size between the reservoir pre- and post-filling stages. Yes As of now, 5000 giant otters are left in the world. 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). In total, 172 cubs were observed in 78 litters between 1991 and 2006. As all suitable territories in Manu have now been occupied by resident groups and there are more non-breeding transients in the system, intraspecific competition is likely to increase in the future, with a consequent decrease in r. Male and female giant otters show very similar traits with respect to average ages at first litter (female 4.4 yrs, male 4.6 yrs. PLOS ONE promises fair, rigorous peer review, 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. Yes 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. Furthermore, in the period 2002–2011, the average annual growth of the economy in Madre de Dios was 7.3%, higher than the national average growth of 6.4% [39]. Sexes were distinguishable when individuals were entirely out of the water, usually when basking or grooming on logs. Unfortunately, this has become the most pressing question regarding the giant river otter. There are many similarities between the social organizations and behaviour of the giant otter and the African wild dog (Lycaon pictus): both live in permanent packs or groups, only the dominant female is assured of breeding, reproduction is monopolized by the dominant male, and subordinates of both sexes help to raise young [47]. For more information about PLOS Subject Areas, click https://doi.org/10.1371/journal.pone.0106202.s001. Pseudo-pregnancies have not been conclusively documented in the wild. Breeding pair duration and reproductive success. the Manu floodplain is assumed to be neither a source nor sink population within the wider Upper Madre de Dios river ecosystem). Separate survivorship curves for males and females upon reaching sexual maturity (2.5 yrs) were constructed where the sex was known (males n = 31; females n = 17, from 177 individuals). They will seek a peaceful place (or "picnic spot") to eat their prey. For more information about PLOS Subject Areas, click Observations of wild and captive otters suggest that giant otters are weaned at approx. 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. https://doi.org/10.1371/journal.pone.0106202.g004. This value of r implies a doubling time (derived from the equation for exponential growth Nt = No.ert by setting Nt/No = 2, and solving for t) of approximately 23 years, which is consistent with the overall trend observed in Figure 1. https://doi.org/10.1371/journal.pone.0106202.t003. The primary objective of the censuses was to count, identify, and record the status of all giant otters within the floodplain of the Manu River in order to determine population size and collect demographic data. Giant Otter Project. 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. We are grateful to Chris Newman and two anonymous reviewers for offering insightful comments on the manuscript. 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. Yes Despite maintaining separate territories, Giant otters are highly social mammals. Furthermore, of the giant otter reproductive pairs that produced litters, almost all did so only once per year, producing relatively small litters in those years when any cubs emerged (mean size = 2.1). Giant otters in the wild can eat caiman, piranhas, and anacondas. Reproductive success is greater in territories with large areas of lake, where more young are produced, and are guarded and provisioned by non-breeding adults. 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. PLoS ONE 9(8): Although cooperation between group members during hunting is not fully understood, larger groups (8 inds.) Males were never observed to become dominant breeders in their natal groups and either form a new group or immigrate into an existing group to occupy the reproductive male position. Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. 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. Reproductive behavior has largely been documented by observations of captive animals. ), average reproductive life-spans (female 5.4 yrs., male 5.2 yrs. Giant Otter's velvet pellets have attracted hunters whose numbers have dropped significantly. They build large dens in riverbanks and give birth to 1-5 babies at a time. DANGER FOR OTTERS IN PROTECTED AREAS. https://doi.org/10.1371/journal.pone.0106202, Editor: Alexander J. Travis, Cornell University College of Veterinary Medicine, United States of America, Received: April 16, 2014; Accepted: July 28, 2014; Published: August 27, 2014. Giant ottters are very sociable animals and often … Otter, any of 13–14 species of semiaquatic mammals that belong to the weasel family and are noted for their playfulness. 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. We assumed a linear relationship between habitat area and population size given the observed relationship between den density and population … Sizeable burrows are then built under fallen logs. Family groups are generally composed of a monogamous breeding pair and their offspring of several years, numbering 2–16 individuals [4], [5], [16], [18]. Present demographic data from the first 16 years of a giant otter research and conservation project conducted in Manu National Park, south-eastern Peru. The Giant Otter (Pteronura brasiliensis) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo. In 11 instances the breeding male disappeared and was replaced by an immigrant adult male. Illegal killing still occurs, often at the hands of fishermen, who see Giant otters as competition for fish. Giant Otters are social creatures who learn from each other and live in tight-knit extended families. 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]. Manu National Park (16,921 km2) lies in the Department of Madre de Dios, south-eastern Peru, at the foothills of the tropical Andes. https://doi.org/10.1371/journal.pone.0106202.s002, https://doi.org/10.1371/journal.pone.0106202.s003. km. During the dry season (April through September), water levels are at their lowest, fish densities at their highest (resource concentration) and habitat conditions at their most stable. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0106202. The data analysis for this paper was generated using [SAS/STAT] software, Version 9.12 of the SAS System for Windows 7, copyright 2002–2008. The family members clear an area beside a stream for their living quarters, of up to 50 sq meters, usually near feeding sites. 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. Most otter groups reacted to the survey canoe by approaching and repeatedly craning head and neck straight out of the water, a behaviour known as ‘periscoping’. here. Giant otters live in small family groups of 3-10 animals. The primary cause for this population decline was poaching for otter pelt. This means that changes in this specific habitat, or impacts there-in, will have severe effects even if only a fraction of the overall area is affected. broad scope, and wide readership – a perfect fit for your research every time. 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. Routes to breeding are as follows: females can either inherit the dominant position in their natal group or they can form a new breeding group elsewhere. Overall, currently Giant otters are classified as Endangered (EN) and theirs numbers today are decreasing. Gestation is between 64 to 77 days [20], [26], [27], [28]. Effective Protected Area design and broader wetland landscape management initiatives are therefore critical for the long term conservation of the species in Madre de Dios. Giant otters hunt opportunistically in non-ideal conditions, (for example, during the high-water period), or more selectively in optimal conditions [16], [24], [25]. This species was excessively hunted up until the late 1970s for its valuable fur. 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]. 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]. Incest was never recorded. Giant otters produce 9 different vocalizations and are very loud. The current total population is estimated to be somewhere between 1000-5000 individuals. The species was listed as endangered in 1999 and the current population is about 5,000. e106202. Each individual is identifiable from infancy by its unique pale throat marking [4], making it possible to avoid double counting and to follow the life histories of animals over successive years. The high degree of reproductive skew found in giant otters, comparable to that in other highly cooperative breeders such as the dwarf mongoose (Helogale purvula) [36], the African wild dog (Lycaon pictus) [13], and the meerkat (Suricatta suricata) [37], means that, over all censuses, only 30% of the population consisted of breeding animals. https://doi.org/10.1371/journal.pone.0106202.t002. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Discover a faster, simpler path to publishing in a high-quality journal. However, this study confirmed the existence of transient groups, fluid single- or mixed-sex associations of multiple non-breeding otters (up to 5 observed) that have not yet secured a territory and do not exhibit strong site fidelity. One to five latrines for communal use are placed along the perimeter of the site. The longest reproductive lifespan was 13 years for males and 11 years for females. 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 species is also found in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname and Venezuela. As a norm, the dominant female of a giant otter group produced one litter per year. However, litters were produced for an average of only 3.2 years (SE 0.43, range 1.0–5.0). The giant otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. Male philopatry was not observed. If typical, this suggests a pre census cub mortality of at least 30%. The implementation of CITES in 1973 reduced the hunting, allowing the population to grow, but the situation for the remaining otters is still critical. It is estimated that 40% of this population consists of recent immigrants attracted by land availability and job opportunities [38]. 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. A giant otter population is typically described as consisting of family groups and of lone dispersers of both sexes. Males can then be distinguished from females by the larger space between the sources of the urine and scat streams [45]. There were about 474 stranded otters in 2016. On average, breeding females produced 6.9 cubs per lifetime (se 1.17). 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). Do giant otters live in a group? We studied population structure and genetic diversity of giant otters from Colombia’s Orinoco basin using analyses of … Only by facilitating the return of giant otters in the Madre de Dios floodplain will the population of the entire watershed reach Ne ≥500 individuals, our minimum conservation goal for a genetically viable population [43]. Although group members hunt together, each individual captures and consumes its own prey. Nature Services Peru, Department of Cusco, Cusco, Perú, Common name: Giant otter, giant Brazilian otter, giant river otter. At the time of censuses, cubs were aged approx. Until 2002, all sexing was based on such opportunistic sightings, so animals that were longer in the population were more likely to be sexed. 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. 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). Conceived and designed the experiments: ES CS JG FH. here. Giant river otters are very sociable and live in families of between 3-10 individuals that hunt together. Frankfurt Zoological Society, Frankfurt, Germany. Yes Social activities include hunting, grooming, resting and communicating. However, this study confirmed the existence of transient groups, fluid single- or mixed-sex associations of multiple non-breeding otters (up to 5 observed) that have not yet secured a territory and … Giant Otter This South American otter is the world's largest, at some 6 feet long. and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Observed group size ranged from 2 to 13, with a mean of 6.0 (n = 117). Yes A further 13 cubs in 9 litters were inferred because they were identified as juveniles in the subsequent census. In none of these cases was the male partner related to the philopatric female. No, Is the Subject Area "Rivers" applicable to this article? No, Is the Subject Area "Reproductive success" applicable to this article? Ages were categorised as: ‘cubs’ up to 0.5 yr, ‘juveniles’ between 0.5 and 1.5 yr of age, ‘sub adults’ between 1.5 and 2.5 yr old, and ‘adults’ at and over 2.5 yr of age. Endangered giant otters, Pteronura brasiliensis, are found along the Amazon and Orinoco rivers and most of their tributaries. The park’s Giant Otter Reserve was opened by Olympic gold swimming medallist Rebecca Adlington on March 2016 and Alex and Mora are favourites with visitors. Average age of first parturition was 4.4 (n = 14, SE 0.43, range 3.0–9.0). 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. Two species are marine; the others live mostly in fresh water. One of the few strongholds of giant otters now lies in the Cantao state park wetlands that nestle between the Amazon rainforest and the … Today, things have changed. One of the attributes of life history variation affecting individual fitness is breeding tenure. Some pups in the wild are taken for pets, and usually die because of the inexperience of caretakers. 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. 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 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]. Over all years, 67.9% of litters were born in the second quarter (beginning of the dry season) and 20.8% in the third quarter (end of the dry season). 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. The area of lake encompassed by a territory predicts group structure: both the size of the groups and the fecundity of the breeding female are proportional to the total lake area within the group territory [unpublished]. Immigrants were only recruited into a resident group if they claimed the dominant breeding status. 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). The vulnerability of the Manu giant otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. 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]. Thirty percent of riverine forests in Madre de Dios (this figure includes those in Protected Areas) have already been destroyed. The giant otter is the longest of the otter species but shares a similar weight with the sea otter. The size of litters when at least one cub emerged averaged 2.1 (SE = 0.10, n = 14), and there was no evidence for a temporal trend (Pearson’s r = −0.26, P = 0.36, n = 14). Giant otters were very nearly extinct by the 1970s. Over the study period, the number of resident giant otter groups increased from a low of 7 in 1991 to a high of 12 in 2005. Once otters become reproductively dominant, individual differences in breeding success depend principally on the duration of dominance tenure (Table S2), although breeding route may also play a role. 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. Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. The new survey indicate again that tourism could have a negative effect on the giant otters. Giant otter populations are in decline, the population is estimated to be between 1,000-4,000 individuals left in the wild. Data from known-age individuals were used to assign ages to the estimated-age animals. High dispersal mortality, especially among transient males, has also been documented in this study. They do everything together and help each other to hunt food. The life table (Table 3, Table S1) generated values of 1.28 for the net reproductive rate (Ro), 8.21 yrs for the generation time (T), and 0.03 for the intrinsic rate of increase (r) of the population.