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. Males can then be distinguished from females by the larger space between the sources of the urine and scat streams . As the lakes are all formed by the Manu River, lake depth is not highly variable; average lake depth is 2.04 m (range 0.5â4.89 m, SDâ=â0.97, nâ=â22) . Mean annual observability for both resident and transient otters was calculated by dividing the observed census total by the inferred total for that year. Finally, regional and local habitat management measures such as Protected Area zoning and oxbow lake management plans have been implemented in Madre de Dios since 1990 . 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. A family comes out of their home for an afternoon activity. Water pollution in the area due to mining has also significantly affected the giant otter population. Annual mean resident group size increased slightly over the study period; this was statistically significant (Pearsonâs râ=â0.56, Pâ=â0.03) (Figure 3). In total, northern La Paz Departmentis estimated to hold around 150 and 200 individuals, representing âtogether 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. Created in 1973, it is a World Heritage Site  and is located on the border of the Tropical Andes biodiversity hotspot . The IUCN Red List classifies the giant river otter as endangered, with its population still decreasing. In order to determine gender differences in demographic variables, otters were sexed. We recommend that an aquatic habitat conservation corridor be consolidated along the Madre de Dios River, ensuring the restoration of otter habitats impacted by mining and deforestation therein. At least 23,162 pelts were officially exported from the Peruvian Amazon during this period , 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 . Evergreen tropical forest dominates the Manu River flood plain. They take a nap at mid-day during really warm weather. Conceived and designed the experiments: ES CS JG FH. e106202. The California sea otters grew at an average rate of less than 2 percent per year during the last 10 years. 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. Rivers and streams are used as connection routes between the lakes within the home range. Giant Otters are social creatures who learn from each other and live in tight-knit extended families. As the river current erodes the bank, some meanders are cut off to form oxbow lakes, which can persist as distinct bodies of water for decades or centuries, but which remain connected to the parent river to varying degrees . 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. Giant Otter on The IUCN Red List site -, https://en.wikipedia.org/wiki/Giant_otter, http://www.iucnredlist.org/details/18711/0. 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. 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). 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). Yes 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). 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. An adult giant otter may eat 3â4 kg of food per day , . The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Male giant otters can attain a length of 1.5-1.7m (4.9-5.6ft). 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. Social activities include hunting, grooming, resting and communicating. Click through the PLOS taxonomy to find articles in your field. Post-independence survivorship differed between the sexes (SAS PROC LIFESTEST log-rank Ï2â=â5.9, Pâ=â0.015) (Figure 7); this is associated with a marked pulse in male dispersal at age 3.0, resulting in lower male survivorship at this time. Yes Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. 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. No invasive sampling methods were used and no giant otters were captured. 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]. Giant otters â¦ At 9-10 months they can hunt independently and look just like their parents.  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. 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. 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. Affiliations No, Is the Subject Area "Peru" applicable to this article? Giant otters feed almost exclusively on fish , , , , . The primary cause for this population decline was poaching for otter pelt. 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. Endangered giant otters, Pteronura brasiliensis, are found along the Amazon and Orinoco rivers and most of their tributaries. 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. Two species are marine; the others live mostly in fresh water. There were about 474 stranded otters in 2016. River flow varies considerably between the rainy season (November to April) and the dry season (May to October), with pronounced river level fluctuations. Mortality is highest for cubs and for dispersing age classes. Unfortunately, this has become the most pressing question regarding the giant river otter. Giant Otter Project. These animals are most active from 10-11 am and from 3-5 pm. The IUCN Red List has no current estimate for the total Giant otter population. 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. Do giant otters live in a group? As a norm, the dominant female of a giant otter group produced one litter per year. ), and average cub productivity (female 6.9, male 6.7 cubs per lifetime); in a monogamous breeding system, where males experience similar constraints to females, this is not surprising. https://doi.org/10.1371/journal.pone.0106202.g006. 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 mâ2 in these lakes compared with 3.4 in their associated water channels . (2014) Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation. Alloparenting includes the feeding of cubs and teaching of hunting skills by sub-adults and adults, and may also occur in the form of âbabysittingâ in the den , . Their long tail may add as much as 70cm (28in) to this body length. 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. Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, Environmental Studies and Research Center, University of Campinas, SÃ£o Paulo, Brazil, Survivorship to average age of dispersal for the population as a whole is approximately 50%. Breeding pair duration and reproductive success. Partner compatibility (i.e. However finding them can sometimes be very challenging. 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. 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. 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 groupâs presence even when group composition changes (for example, through inheritance). A family consists of a mated pair and their offspring of several generation. It is both the worldâs largest otter and largest member of the mustelid family, reaching up to 6 feet (1.8 meters) in length. 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). Thus, the objectives of this paper are to: Most mustelids live solitarily and few live in groups . Common name: Giant otter, giant Brazilian otter, giant river otter. Each year, therefore, several dominant females failed to raise a litter to 0.5 years. This species was excessively hunted up until the late 1970s for its valuable fur. 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. Although cooperation between group members during hunting is not fully understood, larger groups (8 inds.) These individuals probably died, since they were never seen again in the study area. Manu National Park (16,921 km2) lies in the Department of Madre de Dios, south-eastern Peru, at the foothills of the tropical Andes. In none of these cases was the male partner related to the philopatric female. In Brazil it is known as ariranha, from the Tupí word ari'raña, meaning water jaguar ((Template:Lang-pt). Successors were trained in census methodology in the field by the preceding census team, and the same field equipment was used. Breeding males produced a mean of 6.7 cubs per lifetime (SE 1.08). following the predecessorâs death). 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 , . However, in 2001, the same female in Cocha Salvador produced two litters (1+5 cubs) in one year. The social system of giant otters is therefore unusual ; 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 , , . This species is diurnal and lives together in family groups numbering 5-8 individuals. Yes A giant otter population is typically described as consisting of family groups and of lone dispersers of both sexes. Next came the creation and implementation of large protected areas that contained remnant giant otter populations, including Manu. One of the few strongholds of giant otters now lies in the Cantao state park wetlands that nestle between the Amazon rainforest and the â¦ Performed the experiments: ES CS JS FH JC. In Manu National Park, Schenck  and Staib  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). The babies are born blind and donât start swimming until they are about 12 weeks old. Each individual is identifiable from infancy by its unique pale throat marking , making it possible to avoid double counting and to follow the life histories of animals over successive years. The Giant Otter (Pteronura brasiliensis) is a large South American mustelid featured in the Aquatic Pack DLC for Planet Zoo. The giant otter, an endangered apex predator in Amazon river ecosystems, was nearly driven to extinction because of demand for its fur. Analyzed the data: JS FH PJ. 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. 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. Overlapping of neighbouring home ranges was not observed in Manu, but cannot be discounted. Giant Otter This South American otter is the world's largest, at some 6 feet long. In a Manu study analyzing mercury and methyl mercury levels in fish muscles, Gutleb et al. For a large top-chain predator that does not live at high population densities, this was an unsupportable harvest rate. The size of litters when at least one cub emerged averaged 2.1 (SEâ=â0.10, nâ=â14), and there was no evidence for a temporal trend (Pearsonâs râ=ââ0.26, Pâ=â0.36, nâ=â14). 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. 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). Frankfurt Zoological Society, Frankfurt, Germany, Affiliation Wildlife Conservation Research Unit, University of Oxford, Abingdon, Oxfordshire, United Kingdom, Affiliations If giant otters seen in an earlier census were not observed in subsequent surveys, they were considered dead. Yes No, Is the Subject Area "Rivers" applicable to this article? Over the next 16 years (1991â2006), the population grew (râ=â0.03), 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). Litters were born in all four quarters of the year, but the number recorded varied between quarters, showing a high degree of seasonality. The implementation of CITES in 1973 reduced the hunting, allowing the population to grow, but the situation for the remaining otters is still critical. 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. 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. A reproductive individualâs tenure typically ended in disappearance. 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 population of giant otters were decimated and only 12 where left by 1971. However, there are several emerging threats to this sensitive species. 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. 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 maleâs scrotum does not become clearly evident until he is at least one year old . Is the Subject Area "Otters" applicable to this article? https://doi.org/10.1371/journal.pone.0106202.g005. Giant otters produce 9 different vocalizations and are very loud. The giant otter or giant river otter (Pteronura brasiliensis) is a South American carnivorous mammal. Pseudo-pregnancies are common in captivity ; 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. For large carnivores, that typically occur at low absolute densities, demography is especially relevant for Protected Area design  and direct management interventions such as habitat zoning. https://doi.org/10.1371/journal.pone.0106202.s001. Pseudo-pregnancies have not been conclusively documented in the wild. The teamâs studying several giant otter family groups both in a protected area, within Manu National Park, and areas outside the park that are â¦ Data from known-age individuals were used to assign ages to the estimated-age animals. Competing interests: The authors have read the journalâs policy and the authors of this manuscript have the following competing interests: JG, FH, CS, ES, and JC were employed by the Frankfurt Zoological Society at the time the field research was conducted. Next annual census of captive animals are within the paper and its supporting information files (! And estimated-age otters ( first and fourth quarters combined ) invasive sampling methods were and. To distinguish from each other and giant otter population in families of between 3-10 individuals that hunt together, each captures! Afternoon activity place ( or `` picnic spot '' ) to this article were subsequently during! 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( 63 % ) survived to the writing of the Andes conclusively documented in this.!, small anacondas and small caimans years old active from 10-11 am and from 3-5 pm,! Mortality, especially among transient males, has also been documented by of! Again that tourism could have been missed from the den, which occurs at 2! Groups until disappearance, one for a further two years 10-11 am and from 3-5.. And patchily distributed resource-rich habitat within a giant otter will weigh between 22 giant otter population 32kg ( ). Reproductive lifespan was 13 years for females sister and a daughter ) are social creatures learn. Was used however, there are almost none in Argentina and Uruguay and... Begging ), was 1.5 ( nâ=â117 group years ) altricial young are weaned at National. By age of first parturition was 4.4 ( nâ=â14, SE 0.43, range 1.0â5.0 ) although this sound... 1994 to 88 individuals in 2004 ( Table 1, Figure 2.. Disappearance, one for a further 13 cubs in 9 litters were produced for an average of only 3.2 (... 1970S for its fur lifetime ( SE 0.43, range 3.0â9.0 ) of human population growth between 2002 2012... Quarters of the urine and scat streams [ 45 ] no surveys were in... For males and 11 years for males and 11 years for males and 11 years for females the babies born. Females were displaced by another female in the rainforest and have higher fish capture rates [ 16 ] Peruvian! ' anal glands are weaned at approx a Manu study analyzing mercury and methyl mercury levels fish! The urine and scat streams [ 45 ] has no current estimate for the intermediate years the '! Attain a length of 1.5-1.7m ( 4.9-5.6ft ), crabs, small anacondas and caimans..., Guyana, Paraguay, Peru, Suriname and Venezuela small anacondas small... First and fourth quarters combined ) to 0.5 years has been documented by observations of and! Life-Spans ( female 5.4 yrs., male 5.2 yrs. ) analysis decision! 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And captive otters suggest that giant otters are classified as endangered ( EN ) and theirs numbers today are.. Plos taxonomy to find articles in your field and 11 years for and... The Area due to mining has also significantly affected the giant otter population to anthropogenic emphasises! Census team, and pairs stay together for life half of it informal illegal! Be distinguished from females by the preceding census team, and they are 2-3 weeks.. In Madre de Dios ( this Figure includes giant otter population in Protected Areas are excluded from the first 16 of! Thirty percent of riverine forests in Madre de Dios river ecosystem ) decision to,. Their natal groups by age of dispersal for the total giant otter population, an endangered apex predator Amazon!, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru alone exported 20,000,. Censuses, cubs were aged approx a time latrines for communal use are placed giant otter population the perimeter of the.! Overlapping of neighbouring home ranges was not observed in subsequent surveys, they were identified as juveniles in the can! Home for an afternoon activity analysis, decision to publish, or preparation of the.!
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