Citation: Groenendijk J, Hajek F, Johnson PJ, Macdonald DW, Calvimontes J, Staib E, et al. However, otters have another important sensory organ at their disposal, called vibrissae. Reproductive animals usually remained in their home range until death or disappearance (in 38 of 40 cases). Otter groups tend to maintain these core territories throughout the year and from year to year; long-term spatial fidelity therefore permits retrospective inference of a group’s presence even when group composition changes (for example, through inheritance). 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 mean annual observability of resident groups was 85% (range 71–100%), while that of transients was 59% (range 0–100%). PLoS ONE 9(8): Subspecies are formed by the evolution of at least two populations in relative isolation that accumulate genetic differentiation (Zink, 2004). Observations of captive individuals suggest that giant otters of both sexes reach sexual maturity at between 2 and 3 years of age [20], [22]. 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. The average rate of human population growth between 2002 and 2012 was 3%, the highest in the country [38]. Of 177 cubs, 111 (63%) survived to the next annual census. 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). Each year, therefore, several dominant females failed to raise a litter to 0.5 years. Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. ... How the world’s largest rhino population dropped by 70 percent—in a decade. Giant otters are towards the slow end of the fast-slow continuum in mammal life history strategies explored by Promislow & Harvey [35]. Giant otters hunt opportunistically in non-ideal conditions, (for example, during the high-water period), or more selectively in optimal conditions [16], [24], [25]. Yes Incest was never recorded. https://doi.org/10.1371/journal.pone.0106202.g004. Censuses were coordinated by Staib and Schenck between 1991 and 1996, by Groenendijk and Hajek between 1999 and 2005, and by Calvimontes in 2006. Although group members hunt together, each individual captures and consumes its own prey. 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. The hunting decimated their populations. 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.g001. Life expectancy peaks between 4.5 and 5.5 years, with the longest-lived male and female last seen at 15.5 years and at least 13.5 years old respectively. Giant otter population size estimates did not scale to the newly available habitat area. Their webbed paws combined with their flexible, muscular bodies and long tails help them navigate the river with ease. here. following the predecessor’s death). https://doi.org/10.1371/journal.pone.0106202.g005. Common name: Giant otter, giant Brazilian otter, giant river otter. However, it is estimated that there is between 1000 and 5000 Giant Otters remaining left in the wild today, which makes these beautiful and charismatic animals vulnerable to extinction. 's' : ''}}. 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. In a Manu study analyzing mercury and methyl mercury levels in fish muscles, Gutleb et al. It turns out the thick, luscious fur that keeps them dry and warm has been a long coveted possession of humans. The Manu population was sub-divided into known-age (i.e. 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. 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. 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. Present demographic data from the first 16 years of a giant otter research and conservation project conducted in Manu National Park, south-eastern Peru. Giant otters are an endangered species living in the Amazon, Orinoco, and La Plata river systems in large, gregarious families. The giant river otter (Pteronura brasiliensis) is the largest member of the mustelid family, which includes otters, weasels, and ferrets, and are by far the loudest member of the group.Giant river otters are very sociable and live in families of between 3-10 individuals that hunt together. 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. 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]. We observed four groups moving litters of young cubs between dens, estimated at between two weeks and one month old. Females start dispersing as young as 1 year old but may stay on in their natal territories up to two years longer than males (6.5 years). The Giant Otter (Pteronura brasiliensis Otter) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo.. Zoopedia Description General. Both displaced females stayed on in their groups until disappearance, one for a further two years. Manu National Park (16,921 km2) lies in the Department of Madre de Dios, south-eastern Peru, at the foothills of the tropical Andes. The giant otter is a large semi-aquatic mammal that lives in the Amazon River … Copyright: © 2014 Groenendijk et al. PRELIMINARY SURVEY OF GIANT OTTERS ALONG THE RIO SAMIRIA The third important tropical reserve of Peru (besides Manu National Park and the reserve of Tambopata-Candamo) is located in the Department Loreto in the Northern part of the country: the national reserve of Pacaya-Samiria ( Fig. A further 13 cubs in 9 litters were inferred because they were identified as juveniles in the subsequent census. If Protected Areas are excluded from the analysis, the situation is much worse. Performed the experiments: ES CS JS FH JC. 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. 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). Litter size estimates are thus minima. Today we're going to learn more about where they live, how their populations are changing and some cool facts about the giant otter. Uncategorized 0 0 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. Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. No, Is the Subject Area "Peru" applicable to this article? These are the longest recorded ages for free ranging giant otters. Up until the 1970's the giant otter was hunted for pelts used to make human coats, scarves and other cold weather apparel. PLOS ONE promises fair, rigorous peer review, begging), sub adults and adults are more difficult to distinguish from each other. 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. Territories do not appear to change in size with the seasons, although different microhabitats are used in accordance with fluctuations in water levels. Although this might sound like a camping trip for a human family, this is actually the life of the giant otter. 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. Although cubs and juveniles are easily recognized by their size and behaviour (e.g. No, Is the Subject Area "Census" applicable to this article? Giant otter facts, pictures, video and in-depth information. 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. However, the most serious threat to giant otter populations today is habitat destruction. 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. Although there is somewhat limited data about the exact number of giant otters in the wild, scientists agree that they are an endangered species, in danger of going extinct. 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. 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). 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. To assess the impacts of mega-dams on this apex-predator, we surveyed the giant otter population across the 443,772-hectare Balbina Hydroelectric Reservoir of central Brazilian Amazonia between 14 and 25 years after this reservoir creation. 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. 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. Contributed to the writing of the manuscript: JG FH PJ CS DM. https://doi.org/10.1371/journal.pone.0106202.t002. Earn Transferable Credit & Get your Degree. Thick and water repellent, their fur keeps their skin dry despite a mostly aquatic lifestyle. San Diego Zoo Global Peru, Department of Cusco, Cusco, Perú, Trees surround them in the tropical forest, providing shade in the heat of the midday sun. They are so adept with their teamwork, they easily outcompete larger predators like jaguars and caiman for fish. 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]. Yes The constant need for food requires the family to work together. No, Is the Subject Area "Rivers" applicable to this article? 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. Reproductive suppression is likely to occur in giant otters, as only the dominant pair in each family breeds [4]. Perform a cohort life history analysis with these data in order to parameterise a life table and calculate the net reproductive rate, generation time and intrinsic rate of increase for the Manu population. We used both male and female offspring because many cubs could not be sexed. In Bolivia it is distributed in remote areas or in protected areas in the Pando, Beni, northern … However, sexing was more difficult in adult females that had not lactated, or in cubs, juveniles and sub adults of both sexes. River flow varies considerably between the rainy season (November to April) and the dry season (May to October), with pronounced river level fluctuations. Create your account, Already registered? The Giant River Otter only lives in three river systems: the Amazon, Orinoco and La Plata. Giant otter populations are in decline, the population is estimated to be between 1,000-4,000 individuals left in the wild. Analyzed the data: JS FH PJ. Giant Otter was listed as endangered in 1999 and has a current population of about 5,000. 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. 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. 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. 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. Their numbers are currently declining, with no population recovery in sight. After 1980s, the northern population off southern Alaska has not shown any reduction and it has now become stabilized. 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. 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). These individuals probably died, since they were never seen again in the study area. The endangered giant river otter is in trouble with a declining population throughout its range in South America. 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 2013 she became the species coordinator of the IUCN of the otter expert group. How Long is the School Day in Homeschool Programs? In none of these cases was the male partner related to the philopatric female. Giant otters are the largest of any otter in the world growing up to 1.8m. 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. Riverine forests are the most endangered ecosystem in the Department of Madre de Dios due to the concentration of gold mining, logging and agricultural activities in floodplains, highlighting the need for a giant otter habitat conservation corridor along the Madre de Dios River. The rate of expansion jumped from 2,166 ha per year before 2008 to 6,145 ha per year thereafter. 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. No, Is the Subject Area "Flooding" applicable to this article? These beautiful creatures, covered in muscles coated with a dark brown fur are endangered due to habitat destruction and hunting. 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.
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