Felipe Zilio - Academia.edu (original) (raw)
Papers by Felipe Zilio
Background Raptor distributions and abundances are poorly known in southern Brazil. Given that... more Background
Raptor distributions and abundances are poorly known in southern Brazil. Given that raptors have low population densities, methods typically applied to census birds are usually inappropriate for surveying raptors. Roadside surveys allow large areas to be searched at a relatively low cost and are often applied to count raptors. We conducted eight paired roadside surveys (roadside point transects and roadside strip transects of 54.5 ~ 58.6 km long) to assess the species richness and abundance of raptors in two grassland landscapes of southern Brazil and to compare results of the two methods.
Results
In total, 1,890 observations of 18 raptor species (118.13 individuals (ind.)/transect) were recorded. Raptor abundances were higher in the altitudinal grasslands (299.25 ± 48.91 ind./transect) than in the coastal plain (86.63 ± 44.04 ind./transect). Abundances were higher when raptors were surveyed with point transects (9.38 ind. · [10 km2]−1 · h−1) than with strip transects (3.55 ind. · [10 km2] −1 · h−1). No significant differences were found in relation to species richness, although five species were exclusively recorded with point transects versus one with strip transects.
Conclusions
Roadside point transects may reduce bias due to differences in species detection caused by habitat features and in abundance estimates resulting from survey habitat being disproportional to their availability. Point counts may enhance the quality of the search for raptors in a surveyed area, increasing the detection probability. The choice of survey method depends on the objectives of the study, but our results favor the use of point transects rather than strip transects to survey raptors in open landscapes.
Keywords:
Diurnal raptors; Open landscapes; Point transect; Roadside survey; Strip transect"
ABSTRACT.— We provide the first record of breeding of the Ornate Hawk-Eagle (Spizaetus ornatus) f... more ABSTRACT.— We provide the first record of breeding of the Ornate Hawk-Eagle (Spizaetus ornatus) for southern Brazil. In September 2005 a nest was found inside the reservoir of the Barra Grande Hydroelectric Power Station, northern Rio Grande do Sul. On the nest there was a nestling around two months old. Based in prey remains collected on the nest, birds were the main item in diet. This is an endangered species in the Atlantic Rain Forest biome in Brazil and the presence of the nest and nestling offer evidence of reproduction in Southern Brazil.
Resumo. -O gavião-de-sobre-branco (Buteo leucorrhous) no sul do Brasil: status, conservação e a p... more Resumo. -O gavião-de-sobre-branco (Buteo leucorrhous) no sul do Brasil: status, conservação e a primeira descrição do ninho da espécie. -O gavião-de-sobre-branco é uma espécie florestal rara ao leste de sua distribuição, no bioma Mata Atlântica, com poucos registros recentes para Brasil. A biologia reprodutiva da espécie é pouco conhecida, oriunda de poucos relatos, sem descrição detalhada do ninho ou período reprodutivo. Nós apresentamos novos registros para a espécie no sul do Brasil coletados durante um período de sete anos de amostragens de aves de rapina na bacia do rio Pelotas e na bacia do rio Guaporé, no sul do Brasil. Também apresentamos o primeiro registro de nidificação da espécie na Mata Atlântica, com descrição detalhada de um ninho e ovos. Foram observados 95 gaviões, sendo apenas um registro ocorrido na bacia do rio Guaporé e um total de 35 indivíduos estimados para a bacia do rio Pelotas. Em sua maioria foram observados indivíduos solitários, mas em sete ocasiões foram observados casais realizando displays aéreos. Um ninho foi encontrado em outubro de 2009, em Campo Belo do Sul, Santa Catarina. O ninho foi construído em um talhão de Pinus elliottii com 27 anos de idade, apresentando sub-bosque relativamente denso e cercado por remanescentes de floresta secundária e campo. O ninho (54 x 38 cm de diâmetro e 18 cm de altura) encontrava-se a 22 m de altura e continha dois ovos de coloração clara, manchados de marrom. Nossos resultados sugerem que a espécie possa estar subestimada no sul do Brasil. Embora os poucos registros recentes tenham ocorrido apenas em grande remanescentes florestais, é possível que a altitude seja o fator mais limitante à distribuição da espécie.
Diet of Falco sparverius Linnaeus 1758 (Aves: Falconidae) and Athene cunicularia (Molina, 1782) (... more Diet of Falco sparverius Linnaeus 1758 (Aves: Falconidae) and Athene cunicularia (Molina, 1782) (Aves: Strigidae) in a dune region on north coast of Rio Grande do Sul, Brazil. Falco sparverius (American Kestrel) and Athene cunicularia (Burrowing Owl) are two, usually sympatric, raptors found in Rio Grande do Sul. Both inhabit open habitats from Alaska and Canada to Tierra del Fuego. Both have similar diets, being generalists that feed on a wide range of prey that includes more invertebrates than vertebrates. The goal of this study is to compare the trophic characteristics of kestrels and owls in the north coast of Rio Grande do Sul, Brazil. The study area includes grasslands, sand dunes and urban areas. From March/2000 to January/2002, 329 kestrel and 577 owl pellets were collected. Prey remains and capture attempts were also recorded. Diet composition of both species was similar. Invertebrates account for 98.5% of the diet for F. sparverius and 95.1% for A. cunicularia. Orthoptera (50.6%), Araneae (17.1%) and Coleoptera (10.5%) were the main prey eaten by F. sparverius, while Orthoptera (49.8%), Coleoptera (22.4%) and Hymenoptera (11.5%) were the main ones for A. cunicularia,. Among vertebrates, A. cunicularia took mainly Anura (3%) and Reptillia (0.9%), while F. sparverius fed on Aves (0.9%) and Anura (0.8%). Invertebrates were found in 100% of pellets of both raptors, while vertebrates were found only in 31.9% of the kestrel and 76% of the owl pellets. The spring diet of kestrels was distinct from other seasons, while summer and winter owl diets were the most distinct. The seasonality suggested by correspondence analysis is supported by the frequencies of the main prey taken along the year. Both raptors took Coleoptera in warm seasons (summer and spring) rather than cold seasons, whereas the opposite is true for Orthoptera. Hymenoptera and Araneae are common in owl pellets during the winter and spring, while kestrels took more spiders during the summer, and Hymenoptera in spring. Trophic niche overlap was high (67%), varying among seasons.
New records of the Ornate Hawk-Eagle Spizaetus ornatus (Accipitridae) in southern Brazil. We pres... more New records of the Ornate Hawk-Eagle Spizaetus ornatus (Accipitridae) in southern Brazil. We present new records of the Ornate Hawk-Eagle for the states of Rio Grande do Sul and Santa Catarina, southern Brazil. Records were made in the townships of Bom Jesus and Esmeralda (Rio Grande do Sul), Capão Alto and Campo Belo do Sul (Santa Catarina), in the period between September 2002 and February 2006. The observation of a young bird suggests the existence of an area of reproduction in the state of Rio Grande do Sul.
Rufous-thighed kite is barely known, specially its reproduction, food and habitat requirements. W... more Rufous-thighed kite is barely known, specially its reproduction, food and habitat requirements. We made opportunistic observations at several sites in the State of Santa Catarina between 1996 and 2006. These observations allowed us to gather data about the feeding behavior, food items, reproduction, seasonality and habitat use of the species. The kite is associated to woodlots. The species is primarily insectivorous, but it may prey upon vertebrates occasionally. We identified two distinct voices, which are described with a spectrographic analysis. The data reported here may contribute to the conservation of the species in Santa Catarina.
Background Raptor distributions and abundances are poorly known in southern Brazil. Given that... more Background
Raptor distributions and abundances are poorly known in southern Brazil. Given that raptors have low population densities, methods typically applied to census birds are usually inappropriate for surveying raptors. Roadside surveys allow large areas to be searched at a relatively low cost and are often applied to count raptors. We conducted eight paired roadside surveys (roadside point transects and roadside strip transects of 54.5 ~ 58.6 km long) to assess the species richness and abundance of raptors in two grassland landscapes of southern Brazil and to compare results of the two methods.
Results
In total, 1,890 observations of 18 raptor species (118.13 individuals (ind.)/transect) were recorded. Raptor abundances were higher in the altitudinal grasslands (299.25 ± 48.91 ind./transect) than in the coastal plain (86.63 ± 44.04 ind./transect). Abundances were higher when raptors were surveyed with point transects (9.38 ind. · [10 km2]−1 · h−1) than with strip transects (3.55 ind. · [10 km2] −1 · h−1). No significant differences were found in relation to species richness, although five species were exclusively recorded with point transects versus one with strip transects.
Conclusions
Roadside point transects may reduce bias due to differences in species detection caused by habitat features and in abundance estimates resulting from survey habitat being disproportional to their availability. Point counts may enhance the quality of the search for raptors in a surveyed area, increasing the detection probability. The choice of survey method depends on the objectives of the study, but our results favor the use of point transects rather than strip transects to survey raptors in open landscapes.
Keywords:
Diurnal raptors; Open landscapes; Point transect; Roadside survey; Strip transect"
ABSTRACT.— We provide the first record of breeding of the Ornate Hawk-Eagle (Spizaetus ornatus) f... more ABSTRACT.— We provide the first record of breeding of the Ornate Hawk-Eagle (Spizaetus ornatus) for southern Brazil. In September 2005 a nest was found inside the reservoir of the Barra Grande Hydroelectric Power Station, northern Rio Grande do Sul. On the nest there was a nestling around two months old. Based in prey remains collected on the nest, birds were the main item in diet. This is an endangered species in the Atlantic Rain Forest biome in Brazil and the presence of the nest and nestling offer evidence of reproduction in Southern Brazil.
Resumo. -O gavião-de-sobre-branco (Buteo leucorrhous) no sul do Brasil: status, conservação e a p... more Resumo. -O gavião-de-sobre-branco (Buteo leucorrhous) no sul do Brasil: status, conservação e a primeira descrição do ninho da espécie. -O gavião-de-sobre-branco é uma espécie florestal rara ao leste de sua distribuição, no bioma Mata Atlântica, com poucos registros recentes para Brasil. A biologia reprodutiva da espécie é pouco conhecida, oriunda de poucos relatos, sem descrição detalhada do ninho ou período reprodutivo. Nós apresentamos novos registros para a espécie no sul do Brasil coletados durante um período de sete anos de amostragens de aves de rapina na bacia do rio Pelotas e na bacia do rio Guaporé, no sul do Brasil. Também apresentamos o primeiro registro de nidificação da espécie na Mata Atlântica, com descrição detalhada de um ninho e ovos. Foram observados 95 gaviões, sendo apenas um registro ocorrido na bacia do rio Guaporé e um total de 35 indivíduos estimados para a bacia do rio Pelotas. Em sua maioria foram observados indivíduos solitários, mas em sete ocasiões foram observados casais realizando displays aéreos. Um ninho foi encontrado em outubro de 2009, em Campo Belo do Sul, Santa Catarina. O ninho foi construído em um talhão de Pinus elliottii com 27 anos de idade, apresentando sub-bosque relativamente denso e cercado por remanescentes de floresta secundária e campo. O ninho (54 x 38 cm de diâmetro e 18 cm de altura) encontrava-se a 22 m de altura e continha dois ovos de coloração clara, manchados de marrom. Nossos resultados sugerem que a espécie possa estar subestimada no sul do Brasil. Embora os poucos registros recentes tenham ocorrido apenas em grande remanescentes florestais, é possível que a altitude seja o fator mais limitante à distribuição da espécie.
Diet of Falco sparverius Linnaeus 1758 (Aves: Falconidae) and Athene cunicularia (Molina, 1782) (... more Diet of Falco sparverius Linnaeus 1758 (Aves: Falconidae) and Athene cunicularia (Molina, 1782) (Aves: Strigidae) in a dune region on north coast of Rio Grande do Sul, Brazil. Falco sparverius (American Kestrel) and Athene cunicularia (Burrowing Owl) are two, usually sympatric, raptors found in Rio Grande do Sul. Both inhabit open habitats from Alaska and Canada to Tierra del Fuego. Both have similar diets, being generalists that feed on a wide range of prey that includes more invertebrates than vertebrates. The goal of this study is to compare the trophic characteristics of kestrels and owls in the north coast of Rio Grande do Sul, Brazil. The study area includes grasslands, sand dunes and urban areas. From March/2000 to January/2002, 329 kestrel and 577 owl pellets were collected. Prey remains and capture attempts were also recorded. Diet composition of both species was similar. Invertebrates account for 98.5% of the diet for F. sparverius and 95.1% for A. cunicularia. Orthoptera (50.6%), Araneae (17.1%) and Coleoptera (10.5%) were the main prey eaten by F. sparverius, while Orthoptera (49.8%), Coleoptera (22.4%) and Hymenoptera (11.5%) were the main ones for A. cunicularia,. Among vertebrates, A. cunicularia took mainly Anura (3%) and Reptillia (0.9%), while F. sparverius fed on Aves (0.9%) and Anura (0.8%). Invertebrates were found in 100% of pellets of both raptors, while vertebrates were found only in 31.9% of the kestrel and 76% of the owl pellets. The spring diet of kestrels was distinct from other seasons, while summer and winter owl diets were the most distinct. The seasonality suggested by correspondence analysis is supported by the frequencies of the main prey taken along the year. Both raptors took Coleoptera in warm seasons (summer and spring) rather than cold seasons, whereas the opposite is true for Orthoptera. Hymenoptera and Araneae are common in owl pellets during the winter and spring, while kestrels took more spiders during the summer, and Hymenoptera in spring. Trophic niche overlap was high (67%), varying among seasons.
New records of the Ornate Hawk-Eagle Spizaetus ornatus (Accipitridae) in southern Brazil. We pres... more New records of the Ornate Hawk-Eagle Spizaetus ornatus (Accipitridae) in southern Brazil. We present new records of the Ornate Hawk-Eagle for the states of Rio Grande do Sul and Santa Catarina, southern Brazil. Records were made in the townships of Bom Jesus and Esmeralda (Rio Grande do Sul), Capão Alto and Campo Belo do Sul (Santa Catarina), in the period between September 2002 and February 2006. The observation of a young bird suggests the existence of an area of reproduction in the state of Rio Grande do Sul.
Rufous-thighed kite is barely known, specially its reproduction, food and habitat requirements. W... more Rufous-thighed kite is barely known, specially its reproduction, food and habitat requirements. We made opportunistic observations at several sites in the State of Santa Catarina between 1996 and 2006. These observations allowed us to gather data about the feeding behavior, food items, reproduction, seasonality and habitat use of the species. The kite is associated to woodlots. The species is primarily insectivorous, but it may prey upon vertebrates occasionally. We identified two distinct voices, which are described with a spectrographic analysis. The data reported here may contribute to the conservation of the species in Santa Catarina.