An average giant otter will weigh between 22 and 32kg (49-71lbs). 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. They can open their eyes after 1 month and start to regularly follow their parents out of the den. Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. This species is monogamous, and pairs stay together for life. Illegal killing still occurs, often at the hands of fishermen, who see Giant otters as competition for fish. It is both the worldâs largest otter and largest member of the mustelid family, reaching up to 6 feet (1.8 meters) in length. here. When they visit latrines, otters often defecate and urinate simultaneously [4] (fecaluria). Only by facilitating the return of giant otters in the Madre de Dios floodplain will the population of the entire watershed reach Ne â¥500 individuals, our minimum conservation goal for a genetically viable population [43]. https://doi.org/10.1371/journal.pone.0106202.s001. Between the mid 1940s and 1973, when a high demand for giant otter skins led to professional, uncontrolled hunting for the pelt trade, the giant otter was extirpated from much of its southern and easterly range including Uruguay, Paraguay and Argentina, and east of the Tocantins and Parana basins in Brazil [5], [6], [7]. The new survey indicate again that tourism could have a negative effect on the giant otters. Furthermore, in Manu National Park, lakes comprise a crucial and patchily distributed resource-rich habitat within a giant otter territory. We observed four groups moving litters of young cubs between dens, estimated at between two weeks and one month old. Lone and group transients made up 13% (range 4% to 22%) of the censused population, with the total number increasing over the study period (Pearsonâs râ=â0.87, P<0.001). Giant otters produce 9 different vocalizations and are very loud. 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. Nature Services Peru, Department of Cusco, Cusco, Perú, 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. 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. 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. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, Affiliations These animals are most active from 10-11 am and from 3-5 pm. Year-round, peak in late spring-early summer, 2. The Department of Madre de Dios generates 70% of Peruâs artisanal gold production and Peruâs mercury imports have increased exponentially (â¼175 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]. Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. 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. Water pollution in the area due to mining has also significantly affected the giant otter population. Evergreen tropical forest dominates the Manu River flood plain. 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 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. Breeding males produced a mean of 6.7 cubs per lifetime (SE 1.08). No invasive sampling methods were used and no giant otters were captured. 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 âmxâ as half the total number of offspring for each parent. Currently, there are almost none in Argentina and Uruguay, and they are very rare in Paraguay. As no surveys were conducted in 1997 and 1998, animals that were last seen in 1996 were assumed to have died in 1997. Contributed to the writing of the manuscript: JG FH PJ CS DM. The primary cause for this population decline was poaching for otter pelt. ), and have higher fish capture rates [16]. https://doi.org/10.1371/journal.pone.0106202.s002, https://doi.org/10.1371/journal.pone.0106202.s003. The family members clear an area beside a stream for their living quarters, of up to 50 sq meters, usually near feeding sites. 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]. In 1973, the commercial hunting of wildlife was banned in Peru and other countries of the giant otterâs 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. Discover a faster, simpler path to publishing in a high-quality journal. A family consists of a mated pair and their offspring of several generation. No, PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US, https://doi.org/10.1371/journal.pone.0106202. No, Is the Subject Area "Flooding" applicable to this article? A family has a home range of 12 sq. including years when a group was resident but no cubs emerged), was 1.5 (nâ=â117 group years). 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. The established territory is then marked by scent from the animals' anal glands. 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. 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. Rivers and streams are used as connection routes between the lakes within the home range. Yes Social activities include hunting, grooming, resting and communicating. Next came the creation and implementation of large protected areas that contained remnant giant otter populations, including Manu. 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. 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. https://doi.org/10.1371/journal.pone.0106202.g002, https://doi.org/10.1371/journal.pone.0106202.g003, https://doi.org/10.1371/journal.pone.0106202.t001. On average, breeding females produced 6.9 cubs per lifetime (se 1.17). Although cubs and juveniles are easily recognized by their size and behaviour (e.g. The species was listed as endangered in 1999 and the current population is about 5,000. Giant otters are [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 kgâ1 fresh weight, the common standard for human consumption. 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]. 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. No, Is the Subject Area "Census" applicable to this article? 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. If typical, this suggests a pre census cub mortality of at least 30%. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, 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). Observed litter size at time of census ranged from 1 to 5 with a mode of 2 (post-emergence meanâ=â2.2, SEâ=â0.04, nâ=â78). The Giant otter was discovered by Gmelin in 1788. At 9-10 months they can hunt independently and look just like their parents. Of 177 cubs, 111 (63%) survived to the next annual census. 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. and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. As of now, 5000 giant otters are left in the world. Reproductive success of giant otters, over their lifetimes or until truncation at the end of the study period, varied substantially (range 0â25 cubs aged 0.5 years). 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. 0.5 yrs old, well after emergence from the den, which occurs at about 2 months. 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. first recorded as cubs in the study area) and estimated-age otters (first recorded as transients or as group members). 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. Family groups are generally composed of a monogamous breeding pair and their offspring of several years, numbering 2â16 individuals [4], [5], [16], [18]. 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 species is also found in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname and Venezuela. Females show lower mortality than males (Figures 8 and 9) until roughly 8 years old, at which point females start to show higher mortality, potentially due to the fitness costs of raising multiple litters. Yes The Giant Otter is a noisy otter species and has been documented with distinct sounds indicating aggression, alarm and reassurance. https://doi.org/10.1371/journal.pone.0106202.g001. Analyzed the data: JS FH PJ. However, in 2001, the same female in Cocha Salvador produced two litters (1+5 cubs) in one year. Ages were categorised as: âcubsâ up to 0.5 yr, âjuvenilesâ between 0.5 and 1.5 yr of age, âsub adultsâ between 1.5 and 2.5 yr old, and âadultsâ at and over 2.5 yr of age. 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]. Creatures who learn from each other to: most mustelids live solitarily and few live in small groups... Observed census totals ranged from 33 animals in 1994 to 88 individuals in 2004 ( Table 2 ) success tended. As transients or as group members hunt together, each individual captures and its... Thus, the dominant female of a turtle forests in Madre de Dios ( this Figure those. Ages to the next annual census otter populations are in decline, the otter! For an afternoon activity Implications of our findings for giant otter censuses ( giant otter population a maximum of 88 inds )! Peru: Implications for Conservation Subject Area `` Flooding '' applicable to this article and,... Mammals that belong to the weasel family and are very loud of fishermen who... 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