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Guilherme Mourão - One of the best experts on this subject based on the ideXlab platform.
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Giant Otter diet differs between habitats and from fisheries offtake in a large Neotropical floodplain
Journal of Mammalogy, 2020Co-Authors: Caroline Leuchtenberger, William E Magnusson, Marcelo Lopes Rheingantz, Carlos André Zucco, A. C. Catella, Guilherme MourãoAbstract:Giant Otters Pteronura brasiliensis are semiaquatic mammals that mainly eat fish, the abundance of which is affected by seasonal flooding and habitat structure. The piscivorous habits of Giant Otters lead to negative human perception and conflicts with fisheries. We compared Giant Otter feeding habits between seasons and habitats in the Southern Pantanal, Brazil, by analyzing feces collected between September 2008 and June 2011.We investigated whether habitat and season affected P. brasiliensis diet composition and prey size. We calculated the frequency of occurrence, relative frequency, and overlap of fish species eaten by Giant Otters and caught by fishermen. The Giant Otters had a more diverse assemblage of fish prey than the offtake in the fisheries. We did not find strong seasonality in Otter diets, but diet composition and prey size differed between rivers and lakes. The Giant Otter diet had higher overlap with the offtake of sport than with professional fishermen. Although the Otters' piscivorous diet often leads to negative perceptions by humans, the low overlap between Otter diet and species taken in local fisheries suggests that Otters have little effect on the commercial fishery. These results indicate that educational programs could be used to reduce perceived conflict between Giant Otters and fishermen.
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Total mercury concentration in the fur of free-ranging Giant Otters in a large Neotropical floodplain
Environmental research, 2020Co-Authors: Grazielle Cristina Garcia Soresini, Caroline Leuchtenberger, Fabiano Aguiar Da Silva, Guilherme MourãoAbstract:Abstract The Giant Otter, Pteronura brasiliensis, (Zimmermann, 1780), is a semiaquatic carnivore that feeds mainly on fish. Mercury has high toxicity and high potential for bioaccumulation in tissues and biomagnification in organisms through food chains. Thus, as a top predator in the trophic chain, the Giant Otter has the potential to accumulate mercury by biomagnification. The objective of the present study was to measure the total mercury concentration in Giant Otter fur samples from an area in the southern Brazilian Pantanal. Fur samples from 19 Otters from different social groups were collected from captured animals or were sampled with biopsy darts. Total mercury determination was performed by cold steam spectrophotometry. Mercury concentrations found in the Giant Otter fur were 7.15 ± 3.41 μg g−1 (2.01–12.06 μg g−1) dry weight. The values are above to the upper limit found in fur samples of Otter species not exposed to contamination sources, which typically range from 1 to 5 μg g−1. The concentrations found in the study area indicate that even in the southern Pantanal, which is approximately 475 km from gold mining activity, mercury can be considered a threat for Giant Otters, as well as for riverside populations. It is also important to consider that other anthropogenic sources of mercury, such as pesticides used in agriculture, could affect this population.
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RESEARCH ARTICLE Territoriality of Giant Otter Groups in an Area with Seasonal Flooding
2016Co-Authors: Caroline Leuchtenberger, William E Magnusson, Guilherme MourãoAbstract:Territoriality carries costs and benefits, which are commonly affected by the spatial and tempo-ral abundance and predictability of food, and by intruder pressure. Giant Otters (Pteronura bra-siliensis) live in groups that defend territories along river channels during the dry season using chemical signals, loud vocalizations and agonistic encounters. However, little is known about the territoriality of Giant Otters during the rainy season, when groups leave their dry season ter-ritories and follow fish dispersing into flooded areas. The objective of this study was to analyze long-term territoriality of Giant Otter groups in a seasonal environment. The linear extensions of the territories of 10 Giant Otter groups were determined based on locations of active dens, la-trines and scent marks in each season. Some groups overlapped the limits of neighboring ter-ritories. The total territory extent of Giant Otters was correlated with group size in both seasons. The extent of exclusive territories of Giant Otter groups was negatively related to the number of adults present in adjacent groups. Territory fidelity ranged from 0 to 100 % between seasons. Some groupsmaintained their territory for long periods, which demanded constant effort in marking and re-establishing their territories during the wet season. These results indicate that the defense capacity of groups had an important role in the maintenance of Giant Otter territo-ries across seasons, which may also affect the reproductive success of alpha pairs
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Giant Otter alarm calls as potential mechanisms for individual discrimination and sexual selection
Bioacoustics, 2016Co-Authors: Caroline Leuchtenberger, William E Magnusson, Carolina Ribas, Renata S. Sousa-lima, Guilherme MourãoAbstract:AbstractAcoustic variation can convey identity information, facilitate social interactions among individuals and may be useful in identifying sex and group affiliation of senders. Giant Otters live in highly cohesive groups with exclusive territories along water bodies defended by the entire group by means of acoustic and chemical signals. Snorts are harsh alarm calls, emitted in threat contexts, which commonly elicit the cohesion and the alert behaviour of the members of the group. The aim of this study was to determine whether Giant Otter snorts have potential to be used for individual discrimination. We tested this hypothesis by verifying if the acoustic characteristics of snorts vary between two study areas, among social groups and individuals, and between males and females. Snort acoustic variables did not differ significantly among study areas, but varied significantly among groups, individuals and between sexes, with higher discrimination between sexes. The frequency of formants (F1–F5) and formant...
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Distribution and status of Giant Otter (Pteronura brasiliensis) in the Pantanal wetland, Brazil
Latin American Journal of Aquatic Mammals, 2015Co-Authors: Walfrido Moraes Tomas, Carolina Ribas, Caroline Leuchtenberger, Guilherme Mourão, André Restel Camilo, Paulo André Lima Borges, L. A. PellegrinAbstract:The Giant Otter (Pteronura brasiliensis) is listed as vulnerable in Brazil, is included in Appendix I of CITES and is classified as endangered by the IUCN. In Brazil, few viable populations persist outside the Amazon basin and the Pantanal wetland. Furthermore, there is limited information on the distribution and abundance of the existing populations. The aim of this study was to estimate the abundance of Giant Otters in the Pantanal wetland and to discuss the conservation status of this population. From July 2000 to November 2011 we conducted surveys throughout the Pantanal to detect the occurrence of Giant Otters by the observations of active dens and latrines and the direct visualization of the Otters. We also monitored Giant Otter population in five rivers, which allowed us to obtain information on number of individuals, group size and linear density. The species was found to occur in almost every river stretch within the Pantanal wetland, as well as in several aquatic habitat types, indicating a remarkable recovery since the over-hunting during the 1960s. 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. These results indicate that the Pantanal is an important area to preserve the Giant Otter and its habitat, despite the many threats that the species still faces in the region, such as increased vessel traffic, pollution and siltation, as well as disruption of the hydrological characteristics due to the construction of dams and river-bed sedimentation.
Caroline Leuchtenberger - One of the best experts on this subject based on the ideXlab platform.
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Giant Otter diet differs between habitats and from fisheries offtake in a large Neotropical floodplain
Journal of Mammalogy, 2020Co-Authors: Caroline Leuchtenberger, William E Magnusson, Marcelo Lopes Rheingantz, Carlos André Zucco, A. C. Catella, Guilherme MourãoAbstract:Giant Otters Pteronura brasiliensis are semiaquatic mammals that mainly eat fish, the abundance of which is affected by seasonal flooding and habitat structure. The piscivorous habits of Giant Otters lead to negative human perception and conflicts with fisheries. We compared Giant Otter feeding habits between seasons and habitats in the Southern Pantanal, Brazil, by analyzing feces collected between September 2008 and June 2011.We investigated whether habitat and season affected P. brasiliensis diet composition and prey size. We calculated the frequency of occurrence, relative frequency, and overlap of fish species eaten by Giant Otters and caught by fishermen. The Giant Otters had a more diverse assemblage of fish prey than the offtake in the fisheries. We did not find strong seasonality in Otter diets, but diet composition and prey size differed between rivers and lakes. The Giant Otter diet had higher overlap with the offtake of sport than with professional fishermen. Although the Otters' piscivorous diet often leads to negative perceptions by humans, the low overlap between Otter diet and species taken in local fisheries suggests that Otters have little effect on the commercial fishery. These results indicate that educational programs could be used to reduce perceived conflict between Giant Otters and fishermen.
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Total mercury concentration in the fur of free-ranging Giant Otters in a large Neotropical floodplain
Environmental research, 2020Co-Authors: Grazielle Cristina Garcia Soresini, Caroline Leuchtenberger, Fabiano Aguiar Da Silva, Guilherme MourãoAbstract:Abstract The Giant Otter, Pteronura brasiliensis, (Zimmermann, 1780), is a semiaquatic carnivore that feeds mainly on fish. Mercury has high toxicity and high potential for bioaccumulation in tissues and biomagnification in organisms through food chains. Thus, as a top predator in the trophic chain, the Giant Otter has the potential to accumulate mercury by biomagnification. The objective of the present study was to measure the total mercury concentration in Giant Otter fur samples from an area in the southern Brazilian Pantanal. Fur samples from 19 Otters from different social groups were collected from captured animals or were sampled with biopsy darts. Total mercury determination was performed by cold steam spectrophotometry. Mercury concentrations found in the Giant Otter fur were 7.15 ± 3.41 μg g−1 (2.01–12.06 μg g−1) dry weight. The values are above to the upper limit found in fur samples of Otter species not exposed to contamination sources, which typically range from 1 to 5 μg g−1. The concentrations found in the study area indicate that even in the southern Pantanal, which is approximately 475 km from gold mining activity, mercury can be considered a threat for Giant Otters, as well as for riverside populations. It is also important to consider that other anthropogenic sources of mercury, such as pesticides used in agriculture, could affect this population.
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RESEARCH ARTICLE Territoriality of Giant Otter Groups in an Area with Seasonal Flooding
2016Co-Authors: Caroline Leuchtenberger, William E Magnusson, Guilherme MourãoAbstract:Territoriality carries costs and benefits, which are commonly affected by the spatial and tempo-ral abundance and predictability of food, and by intruder pressure. Giant Otters (Pteronura bra-siliensis) live in groups that defend territories along river channels during the dry season using chemical signals, loud vocalizations and agonistic encounters. However, little is known about the territoriality of Giant Otters during the rainy season, when groups leave their dry season ter-ritories and follow fish dispersing into flooded areas. The objective of this study was to analyze long-term territoriality of Giant Otter groups in a seasonal environment. The linear extensions of the territories of 10 Giant Otter groups were determined based on locations of active dens, la-trines and scent marks in each season. Some groups overlapped the limits of neighboring ter-ritories. The total territory extent of Giant Otters was correlated with group size in both seasons. The extent of exclusive territories of Giant Otter groups was negatively related to the number of adults present in adjacent groups. Territory fidelity ranged from 0 to 100 % between seasons. Some groupsmaintained their territory for long periods, which demanded constant effort in marking and re-establishing their territories during the wet season. These results indicate that the defense capacity of groups had an important role in the maintenance of Giant Otter territo-ries across seasons, which may also affect the reproductive success of alpha pairs
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Jaguar mobbing by Giant Otter groups
acta ethologica, 2016Co-Authors: Caroline Leuchtenberger, Samara Bezerra Almeida, Artur Andriolo, Peter G. CrawshawAbstract:Group-living in carnivores is mostly associated with cooperative hunting and anti-predator defense. Giant Otters ( Pteronura brasiliensis ) live in monogamous and cooperative breeding groups, where mechanisms other than cooperative foraging may be driving group maintenance in the species. We herein describe three interactions between Giant Otters and jaguars ( Panthera onca ) observed in the wild, two of which involved groups of Otters and one, a lone individual. In the two group instances, the Otters mobbed the jaguar until it left the area. The mobbing behavior displayed in these instances likely reinforces the advantages of living in groups, reducing predation risk and promoting group cohesion, with resulting territorial and fitness benefits.
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Giant Otter alarm calls as potential mechanisms for individual discrimination and sexual selection
Bioacoustics, 2016Co-Authors: Caroline Leuchtenberger, William E Magnusson, Carolina Ribas, Renata S. Sousa-lima, Guilherme MourãoAbstract:AbstractAcoustic variation can convey identity information, facilitate social interactions among individuals and may be useful in identifying sex and group affiliation of senders. Giant Otters live in highly cohesive groups with exclusive territories along water bodies defended by the entire group by means of acoustic and chemical signals. Snorts are harsh alarm calls, emitted in threat contexts, which commonly elicit the cohesion and the alert behaviour of the members of the group. The aim of this study was to determine whether Giant Otter snorts have potential to be used for individual discrimination. We tested this hypothesis by verifying if the acoustic characteristics of snorts vary between two study areas, among social groups and individuals, and between males and females. Snort acoustic variables did not differ significantly among study areas, but varied significantly among groups, individuals and between sexes, with higher discrimination between sexes. The frequency of formants (F1–F5) and formant...
Jessica Groenendijk - One of the best experts on this subject based on the ideXlab platform.
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Oxford Scholarship Online - Giant Otters: using knowledge of life history for conservation
Oxford Scholarship Online, 2018Co-Authors: Jessica Groenendijk, Frank Hajek, Paul J. Johnson, David W. MacdonaldAbstract:The Giant Otter is an endangered South American carnivore with a facultatively cooperative social system that may be affected by local ecology. This chapter synthesises demographic data arising from a 16 year study of a population inhabiting patchily distributed and resource-rich oxbow lakes in the floodplain of Manu National Park, in the Department of Madre de Dios, Peru. It explores how Giant Otter group size and composition relates to territory size, and how reproductive success is affected by territory quality. The chapter concludes with a discussion on the implications of these findings for Giant Otter conservation in southeastern Peru, in the face of increased human/Giant Otter conflict; tourism; and mining, logging and agricultural pressures, and highlights the need for a Giant Otter habitat conservation corridor along the Madre de Dios River.
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation
2016Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50 % mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Riverine forests are the most endangered ecosystem i
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effects of territory size on the reproductive success and social system of the Giant Otter south eastern peru
Journal of Zoology, 2015Co-Authors: Frank Hajek, Christof Schenck, Jessica Groenendijk, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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Effects of territory size on the reproductive success and social system of the Giant Otter, south‐eastern Peru
Journal of Zoology, 2015Co-Authors: Jessica Groenendijk, Frank Hajek, Christof Schenck, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, south-eastern Peru: implications for conservation.
PloS one, 2014Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. 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.
David W. Macdonald - One of the best experts on this subject based on the ideXlab platform.
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Oxford Scholarship Online - Giant Otters: using knowledge of life history for conservation
Oxford Scholarship Online, 2018Co-Authors: Jessica Groenendijk, Frank Hajek, Paul J. Johnson, David W. MacdonaldAbstract:The Giant Otter is an endangered South American carnivore with a facultatively cooperative social system that may be affected by local ecology. This chapter synthesises demographic data arising from a 16 year study of a population inhabiting patchily distributed and resource-rich oxbow lakes in the floodplain of Manu National Park, in the Department of Madre de Dios, Peru. It explores how Giant Otter group size and composition relates to territory size, and how reproductive success is affected by territory quality. The chapter concludes with a discussion on the implications of these findings for Giant Otter conservation in southeastern Peru, in the face of increased human/Giant Otter conflict; tourism; and mining, logging and agricultural pressures, and highlights the need for a Giant Otter habitat conservation corridor along the Madre de Dios River.
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation
2016Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50 % mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Riverine forests are the most endangered ecosystem i
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effects of territory size on the reproductive success and social system of the Giant Otter south eastern peru
Journal of Zoology, 2015Co-Authors: Frank Hajek, Christof Schenck, Jessica Groenendijk, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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Effects of territory size on the reproductive success and social system of the Giant Otter, south‐eastern Peru
Journal of Zoology, 2015Co-Authors: Jessica Groenendijk, Frank Hajek, Christof Schenck, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, south-eastern Peru: implications for conservation.
PloS one, 2014Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. 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.
Christof Schenck - One of the best experts on this subject based on the ideXlab platform.
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, South-Eastern Peru: Implications for Conservation
2016Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50 % mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Riverine forests are the most endangered ecosystem i
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effects of territory size on the reproductive success and social system of the Giant Otter south eastern peru
Journal of Zoology, 2015Co-Authors: Frank Hajek, Christof Schenck, Jessica Groenendijk, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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Effects of territory size on the reproductive success and social system of the Giant Otter, south‐eastern Peru
Journal of Zoology, 2015Co-Authors: Jessica Groenendijk, Frank Hajek, Christof Schenck, Elke Staib, Paul J. Johnson, David W. MacdonaldAbstract:The link between resource abundance, dispersion and cooperative breeding in mammals has been a topic of much debate among ecologists. The Giant Otter social system is facultatively cooperative. Extended families inhabit home ranges where only a dominant pair breeds, and other family members assist with cub defence and food provision. But this system can be affected by local ecology. In the floodplain of the Manu River, in Manu National Park, Peru, oxbow lakes are patchily distributed and form the resource-rich cores, or territories, of Giant Otter family home ranges. We present data from a long-term study at this site, linking territory size variability to the composition of resident Giant Otter groups and their reproductive success. Territory size predicts group structure; both the size of groups and the number of post-emergence cubs are positively correlated to the total lake area within the group territory. Territories with small lake areas (likely to be poor territories) often support only a pair, and the pair may not breed successfully every year. Cubs are more likely to survive in years when more non-breeding adults are present at the time of emergence. However, there may be a negative effect on survival where more non-breeding adults are present in the subsequent year. Finally, cubs produced in larger territories are more likely to disperse and breed successfully away from the natal territory. We conclude that Giant Otter societies are likely shaped by the spatial dispersion of lakes, and food abundance and dispersion within these rich patches.
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TOTAL MERCURY AND METHYLMERCURY LEVELS IN FISH FROM
2015Co-Authors: Arno C. Gutleb, Christof Schenck, E. StaibAbstract:Abstract: Very little is known about environmental contamination in most Otter species. In the range of the Giant Otter, Pteronura brasiliensis, gold miners discharge a great deal of methylmercury into the environment, and this is known to biomagnify in the food chain. Assays for methylmercury were carried out on fish collected in the Madre de Dios department of Peru, from near gold mining areas, and also from more than 100km away; additional fish were obtained from fish markets. Results show that significant contamination occurs in fish bigger than the normal prey size of the Otters, but at present, there are low levels in prey species- this should be monitored closely in future. Despite growing concern and research interest in the contamination of Otters and their food in Europe and North America (Lutra lutra and Lutra canadensis), very little is known about levels of hazardous substances in Otters from other areas. In particular it could be of interest whether regions far away from industry and civilisation are contaminated too
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Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park, south-eastern Peru: implications for conservation.
PloS one, 2014Co-Authors: Jessica Groenendijk, Frank Hajek, Elke Staib, Paul J. Johnson, David W. Macdonald, Jorge Calvimontes, Christof SchenckAbstract:The Giant Otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. 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. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (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 (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male Giant Otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu Giant Otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. 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.