JÁCOMO, A.T.A.; SILVEIRA, L.; DINIZ-FILHO, J.A.F. 2004. Niche separation between the maned wolf (Chrysocyon brachyurus), the crab-eating fox (Dusicyon thous) and the hoary fox (Dusicyon vetulus) in central Brazil. Journal of Zoology, London 262:99-106. DOI:10.1017/S0952836903004473
Abstract. Four species of canids occur in the Cerrado of central Brazil. Three of them, the maned wolf Chrysocyon brachyurus, the crab-eating fox Dusicyon thous and the hoary fox Dusicyon vetulus, were studied in Emas National Park between 1996 and 1999 to investigate niche separation. The diet of the three species was studied to understand niche breadth and degree of overlap. Habitat and activity patterns were used as second and third ecological parameters to define niche dimensions, and were estimated using camera-trap data. The maned wolf is the largest species, weighing c. 21 kg, and is about three times larger than the crab-eating fox and six times larger than the hoary fox. The major ecological differences between the three species were found in their food niche and habitat use, where crab-eating fox presented higher differences from the hoary fox (Pianka’s index of niche overlap (O) = 0.405). Despite differences in niche breadth, habitat use between the hoary fox and the maned wolf were more similar, explaining their larger overlap, in comparison with habitat use by the crab-eating fox. Activity patterns among the species showed less divergence. The three species presented two activity peaks, one in the dusk–night period and another in the morning period. These data permit a better understanding of the ecological separation of the three Cerrado canids that enables their coexistence.
Mostrando postagens com marcador activity patterns. Mostrar todas as postagens
Mostrando postagens com marcador activity patterns. Mostrar todas as postagens
sábado, 4 de abril de 2015
sábado, 20 de dezembro de 2014
Coexistence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezuelan llanos
SCOGNAMILLO, D.; MAXIT, I.E.; SUNQUIST, M.; POLISAR, J. 2003. Coexistence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezuelan llanos. Journal of Zoology, London 259:269-279.
Abstract. Jaguar Panthera onca and puma Puma concolor are sympatric throughout the jaguar’s distribution. Although several studies have focused on the interactions between these two predators, the ecological and behavioural factors that promote their coexistence remain unclear. The goal of this study was to identify those factors that facilitate the coexistence of these cats in a mosaic landscape in the Venezuelan llanos. The study was conducted from January 1996 until November 1998. Five jaguars and six pumas were captured and radio-collared. A high degree of spatial overlap was observed between jaguars and pumas, which may be related to the abundance and distribution of prey species. At a fine scale, there was little overlap of puma locations with jaguar locations. Both species were more active at night than during daytime, but seasonal differences were detected in the activity levels of these predators. Major segregation was found in food habits. Jaguars selected for large prey and pumas for medium-sized prey. Jaguars selected for capybara Hydrochaeris hydrochaeris and collared peccary Tayassu tajacu and consumed caiman Caiman crocodilus and white-tailed deer Odocoileus virginianus less than expected. Pumas selected just for collared peccary and also killed caiman less than expected. It is suggested that the abundance of medium-sized prey is an ecological factor that is facilitating the coexistence of jaguar and puma in the study area. Habitat heterogeneity may be another influential factor leading to the coexistence. Seasonal differences in activity levels probably reflect differences in the size and species of prey taken by these cats.
Abstract. Jaguar Panthera onca and puma Puma concolor are sympatric throughout the jaguar’s distribution. Although several studies have focused on the interactions between these two predators, the ecological and behavioural factors that promote their coexistence remain unclear. The goal of this study was to identify those factors that facilitate the coexistence of these cats in a mosaic landscape in the Venezuelan llanos. The study was conducted from January 1996 until November 1998. Five jaguars and six pumas were captured and radio-collared. A high degree of spatial overlap was observed between jaguars and pumas, which may be related to the abundance and distribution of prey species. At a fine scale, there was little overlap of puma locations with jaguar locations. Both species were more active at night than during daytime, but seasonal differences were detected in the activity levels of these predators. Major segregation was found in food habits. Jaguars selected for large prey and pumas for medium-sized prey. Jaguars selected for capybara Hydrochaeris hydrochaeris and collared peccary Tayassu tajacu and consumed caiman Caiman crocodilus and white-tailed deer Odocoileus virginianus less than expected. Pumas selected just for collared peccary and also killed caiman less than expected. It is suggested that the abundance of medium-sized prey is an ecological factor that is facilitating the coexistence of jaguar and puma in the study area. Habitat heterogeneity may be another influential factor leading to the coexistence. Seasonal differences in activity levels probably reflect differences in the size and species of prey taken by these cats.
sábado, 21 de dezembro de 2013
Response of leopards to re-introduced tigers in Sariska Tiger Reserve, Western India
MONDAL, K.; GUPTA, S.; BHATTACHARJEE, S.; QURESHI, Q; SANKAR, K. 2012. Response of leopards to re-introduced tigers in Sariska Tiger Reserve, Western India. International Journal of Biodiversity and Conservation 4(5):228-236. doi: 10.5897/IJBC12.014
Abstract. Tigers got exterminated from Sariska Tiger Reserve before 2005. After that, five tigers were re-introduced to Sariska during 2008 to 2010. The present study compared the abundance, site occupancy and temporal activity pattern of leopard before and after tiger re-introduction. The population of leopard was estimated by mark-recapture technique using camera traps during 2008 to 2010 in an effective trapping area of 223.3 km2. Before tiger re-introduction (2008), the leopard density was estimated to be 7.6±0.6 (SE) /100 km2 and after tiger reintroduction it was 6.2±0.8 /100 km2(2009) and 3.1±0.4 /100 km2 (2010). It was observed that the density of leopard declined significantly (Two sample T-Test; P = 0.0002) from 2008 to 2010. Rate of site occupancy was calculated through site-wise capture history of leopard obtained from camera traps. Before tiger re-introduction the probability of site utilization of leopard was 0.75, while after tiger re-introduction probabilities of site utilization of leopard and tiger were estimated at 0.54 and 0.52 respectively and the co-occurrence of both the species was 0.51. Temporal activity patterns of tiger and leopard were investigated from photo captures. Prior to the release of tigers, mean activity time of leopard was 20: 57 h (95% CI 20: 19 to 22: 53) but shifted to 22: 35 h (21: 02 to 01: 25 h) after tiger release (Watson’s U2 test: p<0.005). The present study showed that there was a decline in the leopard population after tiger re-introduction and considerable segregation between the two carnivores along the spatial and temporal axes.
Abstract. Tigers got exterminated from Sariska Tiger Reserve before 2005. After that, five tigers were re-introduced to Sariska during 2008 to 2010. The present study compared the abundance, site occupancy and temporal activity pattern of leopard before and after tiger re-introduction. The population of leopard was estimated by mark-recapture technique using camera traps during 2008 to 2010 in an effective trapping area of 223.3 km2. Before tiger re-introduction (2008), the leopard density was estimated to be 7.6±0.6 (SE) /100 km2 and after tiger reintroduction it was 6.2±0.8 /100 km2(2009) and 3.1±0.4 /100 km2 (2010). It was observed that the density of leopard declined significantly (Two sample T-Test; P = 0.0002) from 2008 to 2010. Rate of site occupancy was calculated through site-wise capture history of leopard obtained from camera traps. Before tiger re-introduction the probability of site utilization of leopard was 0.75, while after tiger re-introduction probabilities of site utilization of leopard and tiger were estimated at 0.54 and 0.52 respectively and the co-occurrence of both the species was 0.51. Temporal activity patterns of tiger and leopard were investigated from photo captures. Prior to the release of tigers, mean activity time of leopard was 20: 57 h (95% CI 20: 19 to 22: 53) but shifted to 22: 35 h (21: 02 to 01: 25 h) after tiger release (Watson’s U2 test: p<0.005). The present study showed that there was a decline in the leopard population after tiger re-introduction and considerable segregation between the two carnivores along the spatial and temporal axes.
sábado, 13 de julho de 2013
Activity, habitat use, density, and reproductive biology of the crab-eating fox (Cerdocyon thous) and comparison with the pampas fox (Lycalopex gymnocercus) in a Restinga area in the southern Brazilian Atlantic Forest
FARIA-CORRÊA, M.; BALBUENO, R.A.; VIEIRA, E.M.; FREITAS, T.R.O. 2009. Activity, habitat use, density, and reproductive biology of the crab-eating fox (Cerdocyon thous) and comparison with the pampas fox (Lycalopex gymnocercus) in a Restinga area in the southern Brazilian Atlantic Forest. Mammalian Biology 74:220-229.
Abstract. The ecology and reproductive biology of the crab-eating fox (Cerdocyon thous) and the pampas fox (Lycalopex gymnocercus) were studied in Itapuã State Park, an Atlantic Forest fragment. In this study we describe their activity patterns (diel, lunar, and seasonal), reproductive period, density, spatial distribution, and habitat overlap. The crab-eating fox was more abundant than the pampas fox, occurring in all types of habitats and overlapping with the pampas fox only in the southern portion of the study area, covered by open vegetation. Both canid species presented nocturnal habits and C. thous showed no significant differences in activity among lunar phases or else year season. The density of C. thous was estimated to be 0.78 ind/km². The crab-eating fox reproduced once a year, generating pups during spring (October to December). In comparison with C. thous populations from lower-latitude regions the relatively low density and one reproductive event per year that we observed are probably related to a colder climate, shorter photoperiod, and shortage of food resources in the winter, characteristic of southern Brazil.
Abstract. The ecology and reproductive biology of the crab-eating fox (Cerdocyon thous) and the pampas fox (Lycalopex gymnocercus) were studied in Itapuã State Park, an Atlantic Forest fragment. In this study we describe their activity patterns (diel, lunar, and seasonal), reproductive period, density, spatial distribution, and habitat overlap. The crab-eating fox was more abundant than the pampas fox, occurring in all types of habitats and overlapping with the pampas fox only in the southern portion of the study area, covered by open vegetation. Both canid species presented nocturnal habits and C. thous showed no significant differences in activity among lunar phases or else year season. The density of C. thous was estimated to be 0.78 ind/km². The crab-eating fox reproduced once a year, generating pups during spring (October to December). In comparison with C. thous populations from lower-latitude regions the relatively low density and one reproductive event per year that we observed are probably related to a colder climate, shorter photoperiod, and shortage of food resources in the winter, characteristic of southern Brazil.
sábado, 27 de abril de 2013
Seasonal activity patterns of rodents in a sagebrush community
O'FARRELL, M.J. 1974. Seasonal activity patterns of rodents in a sagebrush community. Journal of Mammalogy 55(4):809-823.
Abstract. Twelve species of nocturnal rodents were studied on a 2.7-hectare plot of sagebrush desert in west-central Nevada. Six species, Dipodomys merriami, D. ordii, D. panamintinus, D. microps, Onychomys torridus, and Peromyscus maniculatus, were active throughout the year. Four species, Perognathus longimembris, P. formosus, Microdipodops megacephalus, and Reithrodontomys megalotis, hibernated and were active only in spring, summer, and autumn. Onychomys leucogaster and Neotoma lepida were trapped intermittently throughout the year but were not permanente residents on the area. Differences in time of daily activity were found between potential competitors demonstrating a degree of temporal isolation. Time after sunset and amount of moonlight were the two most important factors correlated to rodent activity. Ambient temperature, wind, cloud cover, precipitation, and water vapor pressure had little effect on activity except when extreme conditions prevailed.
Abstract. Twelve species of nocturnal rodents were studied on a 2.7-hectare plot of sagebrush desert in west-central Nevada. Six species, Dipodomys merriami, D. ordii, D. panamintinus, D. microps, Onychomys torridus, and Peromyscus maniculatus, were active throughout the year. Four species, Perognathus longimembris, P. formosus, Microdipodops megacephalus, and Reithrodontomys megalotis, hibernated and were active only in spring, summer, and autumn. Onychomys leucogaster and Neotoma lepida were trapped intermittently throughout the year but were not permanente residents on the area. Differences in time of daily activity were found between potential competitors demonstrating a degree of temporal isolation. Time after sunset and amount of moonlight were the two most important factors correlated to rodent activity. Ambient temperature, wind, cloud cover, precipitation, and water vapor pressure had little effect on activity except when extreme conditions prevailed.
terça-feira, 11 de setembro de 2012
Daily activity patterns of the Atlantic bamboo rat (Kannabateomys amblyonyx) in southern Brazil.
SARTI, P.T; SILVA, R.B.; VIEIRA, E.M. 2012. Daily activity patterns of the Atlantic bamboo rat (Kannabateomys amblyonyx) in southern Brazil. Neotropical Biology and Conservation 7(2):108-113.
Abstract. Several biotic and abiotic factors influence on daily cycles and mammalian life-history patterns. In this paper, we investigated behavioral patterns and diurnal and nocturnal activity of the Atlantic bamboo rat Kannabateomys amblyonyx (Rodentia, Echimyidae) an endemic species of the Brazilian Atlantic Forest. We conducted the study in the southern portion of the species distribution, in patches of an introduced bamboo species (Bambusa tuldoides) that occurred inside native forest areas. We evaluated behavior and activity time of the individuals by conducting scans during nocturnal and diurnal periods (mean scan length – 24 min, range from 2 to 30 min). We considered the following behavioral categories: feeding, moving, self-cleaning and resting. We did not find significant difference between the diurnal and nocturnal activity (randomized MANOVA, SS = 0.07, d.f. = 45, P = 0.59). The Atlantic Bamboo Rat seemed to be active during the entire 24-h daily period, but with activity peaks by the beginning of the night (between 19:00 and 21:00). The low energy quality provided by food (buds, twigs and bamboo leaves) should compel the rodent to eat several times a day in order to supply their metabolic needs. Besides that, predator activity both during day and night, as well as other local environmental characteristics, probably represents relevant factors that influence the 24-h activity patterns of the studied rodent.
Abstract. Several biotic and abiotic factors influence on daily cycles and mammalian life-history patterns. In this paper, we investigated behavioral patterns and diurnal and nocturnal activity of the Atlantic bamboo rat Kannabateomys amblyonyx (Rodentia, Echimyidae) an endemic species of the Brazilian Atlantic Forest. We conducted the study in the southern portion of the species distribution, in patches of an introduced bamboo species (Bambusa tuldoides) that occurred inside native forest areas. We evaluated behavior and activity time of the individuals by conducting scans during nocturnal and diurnal periods (mean scan length – 24 min, range from 2 to 30 min). We considered the following behavioral categories: feeding, moving, self-cleaning and resting. We did not find significant difference between the diurnal and nocturnal activity (randomized MANOVA, SS = 0.07, d.f. = 45, P = 0.59). The Atlantic Bamboo Rat seemed to be active during the entire 24-h daily period, but with activity peaks by the beginning of the night (between 19:00 and 21:00). The low energy quality provided by food (buds, twigs and bamboo leaves) should compel the rodent to eat several times a day in order to supply their metabolic needs. Besides that, predator activity both during day and night, as well as other local environmental characteristics, probably represents relevant factors that influence the 24-h activity patterns of the studied rodent.
sábado, 17 de março de 2012
Ecology of the water opossum Chironectes minimus in Atlantic forest streams of southeastern Brazil
GALLIEZ, M.; LEITE, M.S.; QUEIROZ, T.L.; FERNANDEZ, F.A.S. 2009. Ecology of the water opossum Chironectes minimus in Atlantic forest streams of southeastern Brazil. Journal of Mammalogy 90(1):93-103.
Abstract. We studied the population structure, spatial patterns, and activity patterns of the water opossum (Chironectes minimus) via capture-mark-recapture and radiotelemetry from October 2004 to October 2006 in Atlantic Forest streams in southeastern Brazil. We tested the hypothesis of reproductive seasonality, the usual pattern in neotropical marsupials, by examining recruitment of juveniles. The hypothesis was rejected, supporting the alternative hypothesis that breeding by water opossums was better explained by its habitat characteristics and prey availability than by its phylogenetic ancestry. The observed sex ratio was significantly biased toward males. The home lengths of individual water opossums varied from 844 to 3,724 m. Males had larger home lengths than females, and there were male-male and male-female overlaps. The longer home lengths for males may explain the observed sex ratio bias, because males are more exposed to capture. All individuals used stream stretches with preserved riparian forest, fast-flowing water, and stony substrate. The hypothesis that activity was homogeneously distributed throughout the night was rejected; activity began right after sunset and ended before sunrise, but with higher levels of activity in the first 6 h of the night. Because of anthropogenic alterations of hydrographic basins, water opossums may be threatened by reduction of their main habitat, streams with fast-flowing water and stony substrate.
Abstract. We studied the population structure, spatial patterns, and activity patterns of the water opossum (Chironectes minimus) via capture-mark-recapture and radiotelemetry from October 2004 to October 2006 in Atlantic Forest streams in southeastern Brazil. We tested the hypothesis of reproductive seasonality, the usual pattern in neotropical marsupials, by examining recruitment of juveniles. The hypothesis was rejected, supporting the alternative hypothesis that breeding by water opossums was better explained by its habitat characteristics and prey availability than by its phylogenetic ancestry. The observed sex ratio was significantly biased toward males. The home lengths of individual water opossums varied from 844 to 3,724 m. Males had larger home lengths than females, and there were male-male and male-female overlaps. The longer home lengths for males may explain the observed sex ratio bias, because males are more exposed to capture. All individuals used stream stretches with preserved riparian forest, fast-flowing water, and stony substrate. The hypothesis that activity was homogeneously distributed throughout the night was rejected; activity began right after sunset and ended before sunrise, but with higher levels of activity in the first 6 h of the night. Because of anthropogenic alterations of hydrographic basins, water opossums may be threatened by reduction of their main habitat, streams with fast-flowing water and stony substrate.
sábado, 8 de outubro de 2011
Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco
MAFFEI, L.; TABER, A.B. 2003. Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco. Mastozoologia Neotropical 10(1):154-160.
Abstract. Home range, activity, and habitat use of the crab-eating fox (Cerdocyon thous) in a dry forest. The ranging behaviour of three crab-eating foxes in a dry forest in Santa Cruz, Bolivia was studied using radiotracking. Animals occupied an area between 110 and 280 ha estimated with Minimum Convex Polygon and has a small overlap (27 ha) between ranges. The foxes were principally active at night between 17:00 and 08:00 hours. They preferred riparian forest over chacoan and montane forest habitats, althought the former was less available than the others.
Abstract. Home range, activity, and habitat use of the crab-eating fox (Cerdocyon thous) in a dry forest. The ranging behaviour of three crab-eating foxes in a dry forest in Santa Cruz, Bolivia was studied using radiotracking. Animals occupied an area between 110 and 280 ha estimated with Minimum Convex Polygon and has a small overlap (27 ha) between ranges. The foxes were principally active at night between 17:00 and 08:00 hours. They preferred riparian forest over chacoan and montane forest habitats, althought the former was less available than the others.
sábado, 11 de junho de 2011
Padrão de atividade de Akodon montensis e Oryzomys russatus na Reserva Volta Velha, Santa Catarina, sul do Brasil
GRAIPEL, M.E.; MILLER, P.R.M.; GLOCK, L. 2003. Padrão de atividade de Akodon montensis e Oryzomys russatus na Reserva Volta Velha, Santa Catarina, sul do Brasil. Mastozoología Neotropical 10(2):255-260.
Resumo. São apresentadas informações preliminares sobre o padrão de atividade de duas espécies de roedores em uma área de Floresta Atlântica do sul do Brasil. Sistemas com relógios analógicos foram usados para determinar o horário de captura de pequenos mamíferos e um modelo exponencial foi usado para transformar o número de capturas no padrão de atividade de cada espécie. Foram capturadas três espécies de roedores e três de marsupiais em armadilhas com estes sistemas, porém, analisou-se apenas o padrão de atividade das duas espécies mais abundantes, A. montensis e O. russatus. Os padrões de atividade destas duas espécies foram significativamente diferentes (p < 0,05). A primeira espécie foi caracterizada como possuindo padrão de atividade bicrepuscular enquanto a segunda como nortuna. Os padrões de atividade registrados para estas espécies simpátricas podem ter um importante papel na partição de recursos.
Resumo. São apresentadas informações preliminares sobre o padrão de atividade de duas espécies de roedores em uma área de Floresta Atlântica do sul do Brasil. Sistemas com relógios analógicos foram usados para determinar o horário de captura de pequenos mamíferos e um modelo exponencial foi usado para transformar o número de capturas no padrão de atividade de cada espécie. Foram capturadas três espécies de roedores e três de marsupiais em armadilhas com estes sistemas, porém, analisou-se apenas o padrão de atividade das duas espécies mais abundantes, A. montensis e O. russatus. Os padrões de atividade destas duas espécies foram significativamente diferentes (p < 0,05). A primeira espécie foi caracterizada como possuindo padrão de atividade bicrepuscular enquanto a segunda como nortuna. Os padrões de atividade registrados para estas espécies simpátricas podem ter um importante papel na partição de recursos.
Assinar:
Postagens (Atom)