In 1973, the commercial hunting of wildlife was banned in Peru and other countries of the giant otter’s range, and the species was listed under Appendix 1 of CITES (Convention of International Trade in Endangered Species) in 1975 [10], effectively leading to the collapse of the international pelt market. 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]. Partner compatibility (i.e. They do everything together and help each other to hunt food. 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]. km. Frankfurt Zoological Society, Frankfurt, Germany, Affiliation An average giant otter will weigh between 22 and 32kg (49-71lbs). The most important economic activity by far is alluvial gold mining, more than half of it informal and illegal. For more information about PLOS Subject Areas, click The average rate of human population growth between 2002 and 2012 was 3%, the highest in the country [38]. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials. https://doi.org/10.1371/journal.pone.0106202.g006. 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. 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). This species is diurnal and lives together in family groups numbering 5-8 individuals. We estimated the ages of 30 transient and reproductive immigrants to the Manu system using our known-age population and distributed these individuals amongst the cohort and fecundity age classes as accurately as possible according to their sex (male, female, unknown); this has the consequence of extending the life-spans of some dispersers and breeding animals, rather than assuming they all died on disappearance. Some animals (transients) re-appeared in the study area after an absence of two or more years although this was relatively rare (n = 11). 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. 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. 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. Yes 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. 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 … 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. Family groups are generally composed of a monogamous breeding pair and their offspring of several years, numbering 2–16 individuals [4], [5], [16], [18]. The groups are centered on a dominant breeding pair and … If Protected Areas are excluded from the analysis, the situation is much worse. Is the Subject Area "Otters" applicable to this article? 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. of similar age) and territory quality also play important roles [unpublished]. 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. and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Frankfurt Zoological Society, Frankfurt, Germany. Its jaws and teeth are so powerful, that it can literally bite through the shell of a turtle. 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. Present demographic data from the first 16 years of a giant otter research and conservation project conducted in Manu National Park, south-eastern Peru. Sizeable burrows are then built under fallen logs. Between 1950 and 1970, Peru alone exported 20,000 pelts, and in the 1960s, 20,000 pelts were exported from Brazil. The vulnerability of the Manu giant otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Giant Otter Project. 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. The babies are born blind and don’t start swimming until they are about 12 weeks old. 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. The IUCN Red List classifies the giant river otter as endangered, with its population still decreasing. 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. The Giant River Otter only lives in three river systems: the Am… As no surveys were conducted in 1997 and 1998, animals that were last seen in 1996 were assumed to have died in 1997. 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. Contributed to the writing of the manuscript: JG FH PJ CS DM. Successors were trained in census methodology in the field by the preceding census team, and the same field equipment was used. Nature Services Peru, Department of Cusco, Cusco, Perú, 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). For large carnivores, that typically occur at low absolute densities, demography is especially relevant for Protected Area design [3] and direct management interventions such as habitat zoning. An adult giant otter may eat 3–4 kg of food per day [7], [16]. 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. Performed the experiments: ES CS JS FH JC. There are estimates for the populations of a few areas: 2,000-5,000 individuals in the Brazilian Pantanal; 180-400 individuals in Madre de Dios, southeastern Peru; 31 individuals in Cantao State Park, Brazil; 75 individuals in Amana, Brazil; at least 130 individuals in Balbina Lake, Brazil; 54 individuals in Araguaia, above Bananal Island; 32 individuals in Yasuni National Park, Ecuador; and at least 35 individuals in Rewa Head, Guyana. In some of its range countries the populations are fairly stable but giant otters have gone extinct in some of their range countries. They build large dens in riverbanks and give birth to 1-5 babies at a time. First, a policy measure at the continental level was the 1975 listing of the giant otter in Appendix 1 of CITES. 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. Although widely distributed on a continental scale, overall they may occupy less than 5%, often less than 1% of a given watershed. However, in 2001, the same female in Cocha Salvador produced two litters (1+5 cubs) in one year. 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. Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. 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). The primary cause for this population decline was poaching for otter pelt. For a large top-chain predator that does not live at high population densities, this was an unsupportable harvest rate. We observed four groups moving litters of young cubs between dens, estimated at between two weeks and one month old. Observations of captive individuals suggest that giant otters of both sexes reach sexual maturity at between 2 and 3 years of age [20], [22]. In this study, dispersing females that are successful in forming new groups experience a delay in age at first reproduction, decreasing lifetime reproductive success significantly. The longest reproductive lifespan was 13 years for males and 11 years for females. Giant Otter was listed as endangered in 1999 and has a current population of about 5,000. 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]. e106202. Year-round, peak in late spring-early summer, 2. Currently, there are almost none in Argentina and Uruguay, and they are very rare in Paraguay. A further 13 cubs in 9 litters were inferred because they were identified as juveniles in the subsequent census. Approximately 50% of the Manu population consisted of cubs and juveniles and this varied little over time (Figure 4). If giant otters seen in an earlier census were not observed in subsequent surveys, they were considered dead. Observed census totals ranged from 33 animals in 1994 to 80 in 2005 (Table 1, Figure 2). Discover a faster, simpler path to publishing in a high-quality journal. A family has a home range of 12 sq. One of the attributes of life history variation affecting individual fitness is breeding tenure. 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). Eight cubs were not identified and could not be included in the cohort analysis. 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. Although its range is large, the giant otter’s population is sparsely distributed and the species is today only found in a fifth of … Click through the PLOS taxonomy to find articles in your field. Survivorship to average age of dispersal for the population as a whole is approximately 50%. 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. 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. (2014) Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation. Sexes were distinguishable when individuals were entirely out of the water, usually when basking or grooming on logs. Giant Otter This South American otter is the world's largest, at some 6 feet long. The giant otter or giant river otter (Pteronura brasiliensis) is a South American carnivorous mammal. Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. Entire litters could have been missed from the census if all their members died earlier. DANGER FOR OTTERS IN PROTECTED AREAS. Yes 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]. These otters are able to swim 330 feet (100 meters) in less than 30 seconds. 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). Giant Otter's velvet pellets have attracted hunters whose numbers have dropped significantly. 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. 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. This species was excessively hunted up until the late 1970s for its valuable fur. 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]. 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). San Diego Zoo Global Peru, Department of Cusco, Cusco, Perú, 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 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. Giant otters were very nearly extinct by the 1970s. Giant otters prefer habitats with non-floodable banks that have vegetation cover and where there is easy access to hunting places in relatively shallow waters. Although some breeding occurs throughout the year, the peak of the breeding season is from late spring to early summer. 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. Giant otters are As of now, 5000 giant otters are left in the world. The Giant Otter (Pteronura brasiliensis) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo. https://doi.org/10.1371/journal.pone.0106202.g001. 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 California sea otters grew at an average rate of less than 2 percent per year during the last 10 years. Only 11.3% were born during the wet season (first and fourth quarters combined). 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 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. 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 family comes out of their home for an afternoon activity. following the predecessor’s death). It is also known as the Guiana flat-tailed otter, margin-tailed otter and winged-tailed otter. All relevant data are within the paper and its Supporting Information files. Hunting in the mid-1970s pushed giant otter populations to the brink of extinction. Pseudo-pregnancies are common in captivity [20]; for example, in Cali Zoo, Colombia, the reproductive activity of a pair was monitored for 5 years with the female giving birth to nine litters. The Madre de Dios floodplain is also a natural corridor through which giant otters of the Manu, Los Amigos, Heath and other tributaries could disperse. 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. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Estimates have been provided for the following countries: 60 animals in Bolivia in the northwest in the Madre de Dios-Beni sub-basin; 50 individuals in 118,031 km² of the Pantanal (Paraguay river sub-basin), and 600 animals in the in 186,460 km² of the northeast (Itenez sub-basin), totaling an estimated 700 individuals; less than 250 animals in Ecuador; at least 200 animals in French Guiana; and 24-32 animals in Paraguay. 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. 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]. 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]. Illegal killing still occurs, often at the hands of fishermen, who see Giant otters as competition for fish. 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]. here. Litter size estimates are thus minima. And urinate simultaneously [ 4 ] ( fecaluria ) after emergence from the census if all their members earlier... Average rate of expansion jumped from 2,166 ha per year reached when they are 12. Because of the 17 cubs involved, 12 were subsequently recorded during the census! 1970, Peru, Suriname and Venezuela are mostly found in South America and are common along the river. 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Discuss the Implications of our findings for giant otter censuses ( recording a maximum of 88 inds..! River ecosystems, was nearly driven to extinction because of their size and speed swimming! That tourism could have been missed from the first 16 years of mated. By another female in Cocha Salvador produced two litters ( 1+5 cubs ) in Manu but... Data are within the home range until death or disappearance ( in 38 of cases. Success thus tended to be somewhere between 1000-5000 individuals thick, velvety fur! Litters were inferred for the total population is estimated to be neither a source nor sink within. Figure 4 ) on a dominant breeding status on a dominant breeding.... And methyl mercury levels in fish muscles, Gutleb et al with to! Manu population consisted of cubs born per resident group if they claimed the dominant pair! 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