Dogs can detect scat samples more efficiently than humans: an experiment in a continuous Atlantic Forest remnant

Scat-detection dogs have been used to locate feces of rare and elusive species across tropical biomes. However their detection efficiency in relation to human observers has rarely been evaluated. In this study, we evaluated the ability of a scat detection dog to locate feces in comparison with human researchers. Human researchers and a scat detection dog surveyed for deer (Mazama spp.) feces in dense ombrofilous Atlantic forest in the Paranapiacaba continuum, SP, Brazil. A controlled experiment was used to assess the maximum effective perpendicular distance from a transect search line that the dog could detect a Mazama spp fecal sample. Results from a linear regression model revealed that the maximum effective perpendicular distance from a transect search line that the dog could detect a scat was 7.2 m. The detection success from our surveys in the Atlantic forest was zero for humans and 0.15 samples/ha or 0.20 samples/km walked for the dog team. Our results demonstrated the importance of scat-detection dogs for non invasive sampling and provide data relevant for the design of future studies.

Dogs can detect scat samples more efficiently than humans: an experiment in a continuous Atlantic Forest remnant

Scat-detection dogs have been used to locate feces of rare and elusive species across tropical biomes. However their detection efficiency in relation to human observers has rarely been evaluated. In this study, we evaluated the ability of a scat detection dog to locate feces in comparison with human researchers. Human researchers and a scat detection dog surveyed for deer (Mazama spp.) feces in dense ombrofilous Atlantic forest in the Paranapiacaba continuum, SP, Brazil. A controlled experiment was used to assess the maximum effective perpendicular distance from a transect search line that the dog could detect a Mazama spp fecal sample. Results from a linear regression model revealed that the maximum effective perpendicular distance from a transect search line that the dog could detect a scat was 7.2 m. The detection success from our surveys in the Atlantic forest was zero for humans and 0.15 samples/ha or 0.20 samples/km walked for the dog team. Our results demonstrated the importance of scat-detection dogs for non invasive sampling and provide data relevant for the design of future studies.

Dogs can detect scat samples more efficiently than humans: an experiment in a continuous Atlantic Forest remnant

Scat-detection dogs have been used to locate feces of rare and elusive species across tropical biomes. However their detection efficiency in relation to human observers has rarely been evaluated. In this study, we evaluated the ability of a scat detection dog to locate feces in comparison with human researchers. Human researchers and a scat detection dog surveyed for deer (Mazama spp.) feces in dense ombrofilous Atlantic forest in the Paranapiacaba continuum, SP, Brazil. A controlled experiment was used to assess the maximum effective perpendicular distance from a transect search line that the dog could detect a Mazama spp fecal sample. Results from a linear regression model revealed that the maximum effective perpendicular distance from a transect search line that the dog could detect a scat was 7.2 m. The detection success from our surveys in the Atlantic forest was zero for humans and 0.15 samples/ha or 0.20 samples/km walked for the dog team. Our results demonstrated the importance of scat-detection dogs for non invasive sampling and provide data relevant for the design of future studies.

The role of seed mass on the caching decision by agoutis, Dasyprocta leporina (Rodentia: Agoutidae)

It has been shown that the local extinction of large-bodied frugivores may cause cascading consequences for plant recruitment and overall plant diversity. However, to what extent the resilient mammals can compensate the role of seed dispersal in defaunated sites is poorly understood. Caviomorph rodents, especially Dasyprocta spp., are usually resilient frugivores in hunted forests and their seed caching behavior may be important for many plant species which lack primary dispersers. We compared the effect of the variation in seed mass of six vertebrate-dispersed plant species on the caching decision by the red-rumped agoutis Dasyprocta leporina Linnaeus, 1758 in a land-bridge island of the Atlantic forest, Brazil. We found a strong positive effect of seed mass on seed fate and dispersal distance, but there was a great variation between species. Agoutis never cached seeds smaller than 0.9 g and larger seeds were dispersed for longer distances. Therefore, agoutis can be important seed dispersers of large-seeded species in defaunated forests.

The role of seed mass on the caching decision by agoutis, Dasyprocta leporina (Rodentia: Agoutidae)

It has been shown that the local extinction of large-bodied frugivores may cause cascading consequences for plant recruitment and overall plant diversity. However, to what extent the resilient mammals can compensate the role of seed dispersal in defaunated sites is poorly understood. Caviomorph rodents, especially Dasyprocta spp., are usually resilient frugivores in hunted forests and their seed caching behavior may be important for many plant species which lack primary dispersers. We compared the effect of the variation in seed mass of six vertebrate-dispersed plant species on the caching decision by the red-rumped agoutis Dasyprocta leporina Linnaeus, 1758 in a land-bridge island of the Atlantic forest, Brazil. We found a strong positive effect of seed mass on seed fate and dispersal distance, but there was a great variation between species. Agoutis never cached seeds smaller than 0.9 g and larger seeds were dispersed for longer distances. Therefore, agoutis can be important seed dispersers of large-seeded species in defaunated forests.

The role of seed mass on the caching decision by agoutis, Dasyprocta leporina (Rodentia: Agoutidae)

It has been shown that the local extinction of large-bodied frugivores may cause cascading consequences for plant recruitment and overall plant diversity. However, to what extent the resilient mammals can compensate the role of seed dispersal in defaunated sites is poorly understood. Caviomorph rodents, especially Dasyprocta spp., are usually resilient frugivores in hunted forests and their seed caching behavior may be important for many plant species which lack primary dispersers. We compared the effect of the variation in seed mass of six vertebrate-dispersed plant species on the caching decision by the red-rumped agoutis Dasyprocta leporina Linnaeus, 1758 in a land-bridge island of the Atlantic forest, Brazil. We found a strong positive effect of seed mass on seed fate and dispersal distance, but there was a great variation between species. Agoutis never cached seeds smaller than 0.9 g and larger seeds were dispersed for longer distances. Therefore, agoutis can be important seed dispersers of large-seeded species in defaunated forests.

Hyper abundant mesopredators and bird extinction in an Atlantic forest island

Islands can serve as model systems for understanding how biological invasions affect native species. Here we examine the negative effects of mesopredator mammals on bird richness at Anchieta Island, an 826 ha offshore island in the coast of Brazil. Anchieta Island has the highest density of mammals of the entire Atlantic forest, especially nest predators such as marmosets and coatis, introduced more than 20 years ago. This indiscriminate introduction of mammals may have affected directly the bird community, nowadays represented by 100 species comprised mainly by water-crossing birds, being 73 forest-dwelling species. A small component of these remnant bird species nests in tree holes and on the forest floor, null model analysis suggest that birds within these two nest types are under-represented on Anchieta Island. All guilds were affected negatively, but "opportunist insectivorous/omnivorous". Experiments using artificial nests showed a predation of 73% of nests on the floor while only 26% on the mainland. Camera traps recorded predation by coatis, agoutis, and opossums. The restoration of the bird community on this island is highly constrained by the high density of hyper abundant nest predators.

Hyper abundant mesopredators and bird extinction in an Atlantic forest island

Islands can serve as model systems for understanding how biological invasions affect native species. Here we examine the negative effects of mesopredator mammals on bird richness at Anchieta Island, an 826 ha offshore island in the coast of Brazil. Anchieta Island has the highest density of mammals of the entire Atlantic forest, especially nest predators such as marmosets and coatis, introduced more than 20 years ago. This indiscriminate introduction of mammals may have affected directly the bird community, nowadays represented by 100 species comprised mainly by water-crossing birds, being 73 forest-dwelling species. A small component of these remnant bird species nests in tree holes and on the forest floor, null model analysis suggest that birds within these two nest types are under-represented on Anchieta Island. All guilds were affected negatively, but "opportunist insectivorous/omnivorous". Experiments using artificial nests showed a predation of 73% of nests on the floor while only 26% on the mainland. Camera traps recorded predation by coatis, agoutis, and opossums. The restoration of the bird community on this island is highly constrained by the high density of hyper abundant nest predators.

Hyper abundant mesopredators and bird extinction in an Atlantic forest island

Islands can serve as model systems for understanding how biological invasions affect native species. Here we examine the negative effects of mesopredator mammals on bird richness at Anchieta Island, an 826 ha offshore island in the coast of Brazil. Anchieta Island has the highest density of mammals of the entire Atlantic forest, especially nest predators such as marmosets and coatis, introduced more than 20 years ago. This indiscriminate introduction of mammals may have affected directly the bird community, nowadays represented by 100 species comprised mainly by water-crossing birds, being 73 forest-dwelling species. A small component of these remnant bird species nests in tree holes and on the forest floor, null model analysis suggest that birds within these two nest types are under-represented on Anchieta Island. All guilds were affected negatively, but "opportunist insectivorous/omnivorous". Experiments using artificial nests showed a predation of 73% of nests on the floor while only 26% on the mainland. Camera traps recorded predation by coatis, agoutis, and opossums. The restoration of the bird community on this island is highly constrained by the high density of hyper abundant nest predators.

Frugivoria e dispersão de sementes pelo lagarto teiú Tupinambis merianae (Reptilia: Teiidae)

Tegu lizards have a generalist diet and may play an important role as seed dispersers in semideciduous forests in south-east Brazil. We studied the frugivory and seed dispersal of tegu lizards using captive animals and offering wild fruits from a semideciduous forest. Thirty fruit species were eaten by the lizards in captivity, ranging from 0.81 to 10.0 cm (fruit diameter). Even large fruit adapted to dispersal by large mammals were swallowed (ex. Syagrus oleracea). There were no statistical differences in seed germination between seeds that passed through the lizard gut and the control in Eugenia uniflora (chi2 = 0.69, P>0.50), Genipa americana (chi2 = 6.4, P>0.975), Cereus peruvianus (chi2 = 0.018, P>0.10), and Solanum viarum (chi2 = 6.23, P>0.975). Seed retention time in the tegu gut ranged from 2224 h (Solanum lycocarpum) to 4344 h (for Syagrus romanzoffiana). Our results indicate that tegu lizards have a potential to be an important seed dispersers in the Neotropics.

Os lagartos teiús possuem uma dieta generalista, podendo agir como importantes dispersores de sementes em florestas semidecíduas do sudeste do Brasil. Foram estudadas a frugivoria e a dispersão de sementes de lagartos teiús usando animais em cativeiro, através da oferta de frutos de uma floresta semidecídua. Frutos de trinta espécies vegetais foram oferecidos aos lagartos em cativeiro, com diâmetro variando de 0,81 a 10,0 cm. Não foram encontradas diferenças estatísticas na germinação entre as sementes que passaram pelo trato digestivo do lagarto e as controle de Eugenia uniflora (chi²= 0.69, P>0.50), Genipa americana (chi²= 6.4, P>0.975), Cereus peruvianus (chi²= 0.018, P>0.10), e Solanum viarum (chi²= 6.23, P>0.975). O tempo de retenção da semente no tubo digestivo do teiú variou de 22 a 23 h para Solanum lycocarpum e 43 a 44 h para Syagrus romanzoffiana. Nossos resultados indicam que o lagarto teiú tem potencial para agir como um importante dispersor de sementes nos trópicos.

Frugivoria e dispersão de sementes pelo lagarto teiú Tupinambis merianae (Reptilia: Teiidae)

Tegu lizards have a generalist diet and may play an important role as seed dispersers in semideciduous forests in south-east Brazil. We studied the frugivory and seed dispersal of tegu lizards using captive animals and offering wild fruits from a semideciduous forest. Thirty fruit species were eaten by the lizards in captivity, ranging from 0.81 to 10.0 cm (fruit diameter). Even large fruit adapted to dispersal by large mammals were swallowed (ex. Syagrus oleracea). There were no statistical differences in seed germination between seeds that passed through the lizard gut and the control in Eugenia uniflora (chi2 = 0.69, P>0.50), Genipa americana (chi2 = 6.4, P>0.975), Cereus peruvianus (chi2 = 0.018, P>0.10), and Solanum viarum (chi2 = 6.23, P>0.975). Seed retention time in the tegu gut ranged from 2224 h (Solanum lycocarpum) to 4344 h (for Syagrus romanzoffiana). Our results indicate that tegu lizards have a potential to be an important seed dispersers in the Neotropics.

Os lagartos teiús possuem uma dieta generalista, podendo agir como importantes dispersores de sementes em florestas semidecíduas do sudeste do Brasil. Foram estudadas a frugivoria e a dispersão de sementes de lagartos teiús usando animais em cativeiro, através da oferta de frutos de uma floresta semidecídua. Frutos de trinta espécies vegetais foram oferecidos aos lagartos em cativeiro, com diâmetro variando de 0,81 a 10,0 cm. Não foram encontradas diferenças estatísticas na germinação entre as sementes que passaram pelo trato digestivo do lagarto e as controle de Eugenia uniflora (chi²= 0.69, P>0.50), Genipa americana (chi²= 6.4, P>0.975), Cereus peruvianus (chi²= 0.018, P>0.10), e Solanum viarum (chi²= 6.23, P>0.975). O tempo de retenção da semente no tubo digestivo do teiú variou de 22 a 23 h para Solanum lycocarpum e 43 a 44 h para Syagrus romanzoffiana. Nossos resultados indicam que o lagarto teiú tem potencial para agir como um importante dispersor de sementes nos trópicos.