It is not clear why or how these displacements occurred. Long-term population studies yield the vital rates and demographic data necessary to understand the factors responsible for changes in populations and hence allow the evaluation of the effectiveness of conservation management decisions [1], [2]. 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. We compared changes in habitat area and estimated giant otter population size between the reservoir pre- and post-filling stages. Its thick, velvety brown fur has characteristic white markings around the neck. It is estimated that 40% of this population consists of recent immigrants attracted by land availability and job opportunities [38]. here. 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. Both displaced females stayed on in their groups until disappearance, one for a further two years. 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). We present data on 30 adult females (15 known-age, 15 estimated-age) and 31 adult males (10 known-age and 21 estimated-age) which reproduced successfully, i.e., producing at least one litter to age 0.5 years. It is the longest member of the weasel family, Mustelidae, a globally successful group of predators, reaching up to 1.7 metres (5.6 ft). Environmental Studies and Research Center, University of Campinas, São Paulo, Brazil, In Manu National Park, Schenck [33] and Staib [16] found that home ranges of giant otters typically include one or more oxbow lakes, the associated stretch of river, and adjacent swamp areas and streams (which are inaccessible for observers and therefore make it impossible to define the exact extent of home ranges). No, Is the Subject Area "Lakes" applicable to this article? The groups are centered on a dominant breeding pair and … 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]. 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. 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]. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, The most important economic activity by far is alluvial gold mining, more than half of it informal and illegal. Giant otters hunt opportunistically in non-ideal conditions, (for example, during the high-water period), or more selectively in optimal conditions [16], [24], [25]. Illegal killing still occurs, often at the hands of fishermen, who see Giant otters as competition for fish. Discover a faster, simpler path to publishing in a high-quality journal. Brazil comprises roughly 3 quarters of the giant otter’s entire range. Known throughout much of their range as 'river wolf', they are amongst South America's top carnivores. In areas of low human disturbance, such as Manu National Park, the characteristic behaviour of giant otter groups to investigate intruders ensures that the surveyor is usually not avoided, even by non-habituated groups (although transients are shy and more elusive). The number of litters produced annually in the study area increased significantly over the study period (Pearson’s r = 0.63, P = 0.01) (Figure 5). However, litters were produced for an average of only 3.2 years (SE 0.43, range 1.0–5.0). The giant otter has a handful of other names. 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. They will seek a peaceful place (or "picnic spot") to eat their prey. 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. 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. Furthermore, in Manu National Park, lakes comprise a crucial and patchily distributed resource-rich habitat within a giant otter territory. There are 1-5 pups in a litter (usually 2-3) and they stay in the family den until they are 2-3 weeks old. They do everything together and help each other to hunt food. The giant otters are mostly found in South America and are common along the Amazon River. Yes The total population of giant river otters in the wild could now be as low as 5,000. The dominant pair in each family produces a litter once a year and other adults do not breed [16], [18]. Gestation is between 64 to 77 days [20], [26], [27], [28]. 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. Litter size estimates are thus minima. broad scope, and wide readership – a perfect fit for your research every time. The Giant Otter (Pteronura brasiliensis) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo. 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. The average reproductive lifespan for adult females was 5.4 years (n = 30, SE 0.5, range 1.0–11.0), starting at age 3.0 which was the earliest recorded age of reproduction. The observability of resident and transient otters varied across censuses. Entire litters could have been missed from the census if all their members died earlier. Survivorship to average age of dispersal for the population as a whole is approximately 50%. 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. Immigrants were only recruited into a resident group if they claimed the dominant breeding status. 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]. This species is monogamous, and pairs stay together for life. (2014) Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation. 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. 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. At 9-10 months they can hunt independently and look just like their parents. Animals that were seen in 1996 and again in 1999 were inferred for the intermediate years. 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. 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. No, Is the Subject Area "Rivers" applicable to this article? The giant otter or giant river otter (Pteronura brasiliensis) is a South American carnivorous mammal. Yes The majority of the data analysed here were collected during 14 annual dry season censuses in Manu National Park between 1991 and 2006 (excepting 1997 and 1998). 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. The babies are born blind and don’t start swimming until they are about 12 weeks old. In none of these cases was the male partner related to the philopatric female. Observations of captive individuals suggest that giant otters of both sexes reach sexual maturity at between 2 and 3 years of age [20], [22]. 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. Females are smaller at 1-1.5m (3.3-4.9ft). By age of dispersal, approximately 50% of offspring have died. The species is also found in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname and Venezuela. 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. The population of giant otters were decimated and only 12 where left by 1971. All relevant data are within the paper and its Supporting Information files. Mortality is highest for cubs and for dispersing age classes. However, there are several emerging threats to this sensitive species. As no surveys were conducted in 1997 and 1998, animals that were last seen in 1996 were assumed to have died in 1997. The established territory is then marked by scent from the animals' anal glands. Affiliations No, Is the Subject Area "Conservation science" applicable to this article? Partner compatibility (i.e. Over the next 16 years (1991–2006), the population grew (r = 0.03), with this being due to an increase in (1) the number of breeding groups (from 7 in 1991 to 12 in 2000), and therefore the number of litters per year, (2) the size of groups (from a mean of 4.8 in 1992 to 6.5 in 2004), and (3) the number of transients in the system (from 2 in 1993 to 19 in 2005). 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. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Giant Otter This South American otter is the world's largest, at some 6 feet long. 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. 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. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. Despite this, almost two decades later, in 1993, the species was upgraded from ‘Vulnerable’ to its current ‘Endangered’ IUCN Red List status [11]. No, Is the Subject Area "Reproductive success" applicable to this article? Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. They build large dens in riverbanks and give birth to 1-5 babies at a time. Data from known-age individuals were used to assign ages to the estimated-age animals. Common name: Giant otter, giant Brazilian otter, giant river otter. Frankfurt Zoological Society, Frankfurt, Germany. 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. Of the 17 cubs involved, 12 were subsequently recorded during the annual census. Rarely, an animal lacked a throat marking (n = 3 out of 294 inds.). Although cooperation between group members during hunting is not fully understood, larger groups (8 inds.) Sexing was carried out by observing teats in adult, parous females (four permanently elongated teats due to lactation), or testicles in males: under field conditions, the male’s scrotum does not become clearly evident until he is at least one year old [16]. Lone and group transients made up 13% (range 4% to 22%) of the censused population, with the total number increasing over the study period (Pearson’s r = 0.87, P<0.001). Huge thanks also go to our Peruvian field assistants who shared our lives in the rainforest. It is not clear whether these changes of one member of the breeding pair involved active displacement by the newcomer or whether the newcomer simply occupied an already vacant position (i.e. The Giant River Otter(Pteronura brasiliensis), often referred to as the river wolf, is a species in the Mustelid (weasel) family that is endemic to South America. They can open their eyes after 1 month and start to regularly follow their parents out of the den. One of the few strongholds of giant otters now lies in the Cantao state park wetlands that nestle between the Amazon rainforest and the … 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. In order to determine gender differences in demographic variables, otters were sexed. Observations of wild and captive otters suggest that giant otters are weaned at approx. A giant otter population is typically described as consisting of family groups and of lone dispersers of both sexes. Overall, currently Giant otters are classified as Endangered (EN) and theirs numbers today are decreasing. Hunting in the mid-1970s pushed giant otter populations to the brink of extinction. 6 months old [17], [20] and rely to a great extent on other group members for prey provision until 1.5 years old [16]. Unfortunately, this has become the most pressing question regarding the giant river otter. The Giant Otter is a noisy otter species and has been documented with distinct sounds indicating aggression, alarm and reassurance. Female and male giant otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) Giant otter populations are in decline, the population is estimated to be between 1,000-4,000 individuals left in the wild. Reproductive behavior has largely been documented by observations of captive animals. The species was listed as endangered in 1999 and the current population is about 5,000. The rate of expansion jumped from 2,166 ha per year before 2008 to 6,145 ha per year thereafter. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. 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]. In addition, cubs produced in these territories are more likely to disperse successfully (become breeders at least once away from the natal territory) [unpublished]. Giant otters in the wild can eat caiman, piranhas, and anacondas. In each case, it was not possible to determine whether the former male died due to natural causes, or was evicted from the group by the immigrant male. 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. 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. The new survey indicate again that tourism could have a negative effect on the giant otters. We assumed a linear relationship between habitat area and population size given the observed relationship between den density and population … The IUCN Red List has no current estimate for the total Giant otter population. Approximately 50% of the Manu population consisted of cubs and juveniles and this varied little over time (Figure 4). Each individual otter was noted as either resident (if already present in the study area in 1991 or 1999, or if born in the study area between 1991 and 2006) or immigrant, and labelled for each data point as positively identified, ID uncertain, or inferred. If giant otters seen in an earlier census were not observed in subsequent surveys, they were considered dead. Male philopatry was not observed. Nature Services Peru, Department of Cusco, Cusco, Perú, 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]. 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. Analyzed the data: JS FH PJ. Unfortunately, due to habitat destruction from logging, farming, and mining, the Giant Otter is near extinction, with a wild population … 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]. In Spanish, river wolf (Spanish: [lobo de río] error: {{lang}}: text has italic markup (help)) and water dog (Spanish: [perro de agua] error: {{lang}}: text has italic markup (help)) are used occasionally, though the latter has many other meanings) and may have been more … 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]. In 11 instances the breeding male disappeared and was replaced by an immigrant adult male. Although cubs and juveniles are easily recognized by their size and behaviour (e.g. 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. Two species are marine; the others live mostly in fresh water. It is also known as the Guiana flat-tailed otter, margin-tailed otter and winged-tailed otter. It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. 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. 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. This species is diurnal and lives together in family groups numbering 5-8 individuals. 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. The population survivorship curve (Figure 6) includes data from all cohorts censused (N otters = 177, Table S3). km. 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). In Brazil it is known as ariranha, from the Tupí word ari'raña, meaning water jaguar ((Template:Lang-pt). https://doi.org/10.1371/journal.pone.0106202.t004. 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