Birds of prey pellet analysis: morphometry and consumption interval of captive Accipitridae species / Análise de pelotas de aves de rapina: morfometria e intervalo de consumoem espécies da família Accipitridae em cativeiro

Pellet production is a typical characteristic of the digestive physiology of birds of prey. Alimentary pellets consist of non-digested parts of prey, such as fur, feathers, bones, and parts of insects, that are regurgitated. Obtained dietary samples, such as regurgitated pellets, can noninvasively contribute to the knowledge of the anatomical alimentary channel and the digestive efficiency of birds of prey. The aim of this study was to evaluate the pellet morphometry and meal-to-pellet interval (MPI) of the Accipitridae family subjected to two experimental diets. Heterospizias meridionalis, Rupornis magnirostris, and Geranoaetus albicaudatus were subjected to (1) mice and (2) quail pre-treating diets. Both diets were individually weighed and provided by removing excess feathers, skin, and some viscera. After consumption, the MPI was noted and, immediately after collection, the pellets were carefully weighed on a precision balance and morphometric measurements were taken using a caliper. Pellet weight, length, width, height, and volume were higher when raptors consumed mice. Differences in morphometric characteristics were found between species. Heterospizias meridionalis presented the highest values for the morphometric parameters evaluated. Consumption of mice increased the frequency of regurgitation and the number and weight of pellets egested, indicating that by providing this type of food, we can underestimate the consumption by birds if we do not consider nutritional losses by the pellets when calculating diets. Pellet assessment and MPI are important tools for monitoring the health and nutritional aspects of birds of prey.

A produção de pelotas é uma característica típica da fisiologia digestiva de aves de rapina. As pelotas alimentares consistem em partes não digestíveis de presas como peles, penas, ossos e partes de insetos que são expelidos. A obtenção de amostras como as pelotas podem colaborar de forma não invasiva com o conhecimento da anatomia do canal alimentar e eficiência digestiva de rapinantes. O objetivo desse estudo foi avaliar a morfometria e o intervalo entre consumo e egestão de pelotas (ICP) em indivíduos da família Accipitridae. Heterospizias meridionalis, Rupornis magnirostris e Geranoaetus albicaudatus foram submetidos a dietas pré processadas com(1) camundongos e (2) codornas. Ambas as dietas foram individualmente pesadas e fornecidas após a remoção do excesso de penas, pele e algumas vísceras. Após o consumo, o ICP foi calculado e imediatamente após a coleta as pelotas foram pesadas e avaliadas quanto a medidas morfométricas com a ajuda de um paquímetro. O peso, comprimento, largura, altura e volume das pelotas foram maiores quando as aves consumiram ratos. Diferenças morfométricas foram encontradas entre as espécies. Heterospizias meridionalis apresentaram os valores mais altos para os parâmetros morfométricos avaliados. O consumo de camundongos aumentou a frequência de egestão, o número e o peso das pelotas, indicando que, ao fornecer este tipo de alimento, podemos subestimar o consumo pelas aves se não considerarmos as perdas nutricionais pelas pelotas ao calcular as dietas. A avaliação de pelotas e ICP são ferramentas importantes para monitorar os aspectos sanitários e nutricionais em rapinantes.

Birds of prey pellet analysis: morphometry and consumption interval of captive Accipitridae species / Análise de pelotas de aves de rapina: morfometria e intervalo de consumoem espécies da família Accipitridae em cativeiro

Pellet production is a typical characteristic of the digestive physiology of birds of prey. Alimentary pellets consist of non-digested parts of prey, such as fur, feathers, bones, and parts of insects, that are regurgitated. Obtained dietary samples, such as regurgitated pellets, can noninvasively contribute to the knowledge of the anatomical alimentary channel and the digestive efficiency of birds of prey. The aim of this study was to evaluate the pellet morphometry and meal-to-pellet interval (MPI) of the Accipitridae family subjected to two experimental diets. Heterospizias meridionalis, Rupornis magnirostris, and Geranoaetus albicaudatus were subjected to (1) mice and (2) quail pre-treating diets. Both diets were individually weighed and provided by removing excess feathers, skin, and some viscera. After consumption, the MPI was noted and, immediately after collection, the pellets were carefully weighed on a precision balance and morphometric measurements were taken using a caliper. Pellet weight, length, width, height, and volume were higher when raptors consumed mice. Differences in morphometric characteristics were found between species. Heterospizias meridionalis presented the highest values for the morphometric parameters evaluated. Consumption of mice increased the frequency of regurgitation and the number and weight of pellets egested, indicating that by providing this type of food, we can underestimate the consumption by birds if we do not consider nutritional losses by the pellets when calculating diets. Pellet assessment and MPI are important tools for monitoring the health and nutritional aspects of birds of prey.(AU)

A produção de pelotas é uma característica típica da fisiologia digestiva de aves de rapina. As pelotas alimentares consistem em partes não digestíveis de presas como peles, penas, ossos e partes de insetos que são expelidos. A obtenção de amostras como as pelotas podem colaborar de forma não invasiva com o conhecimento da anatomia do canal alimentar e eficiência digestiva de rapinantes. O objetivo desse estudo foi avaliar a morfometria e o intervalo entre consumo e egestão de pelotas (ICP) em indivíduos da família Accipitridae. Heterospizias meridionalis, Rupornis magnirostris e Geranoaetus albicaudatus foram submetidos a dietas pré processadas com(1) camundongos e (2) codornas. Ambas as dietas foram individualmente pesadas e fornecidas após a remoção do excesso de penas, pele e algumas vísceras. Após o consumo, o ICP foi calculado e imediatamente após a coleta as pelotas foram pesadas e avaliadas quanto a medidas morfométricas com a ajuda de um paquímetro. O peso, comprimento, largura, altura e volume das pelotas foram maiores quando as aves consumiram ratos. Diferenças morfométricas foram encontradas entre as espécies. Heterospizias meridionalis apresentaram os valores mais altos para os parâmetros morfométricos avaliados. O consumo de camundongos aumentou a frequência de egestão, o número e o peso das pelotas, indicando que, ao fornecer este tipo de alimento, podemos subestimar o consumo pelas aves se não considerarmos as perdas nutricionais pelas pelotas ao calcular as dietas. A avaliação de pelotas e ICP são ferramentas importantes para monitorar os aspectos sanitários e nutricionais em rapinantes.(AU)

Insights into the development of a juvenile harpy eagle's hunting skills / Considerações sobre o desenvolvimento da habilidade de caça de um gavião-real juvenil

The post-fledging period is of paramount importance for raptors, since this is when a juvenile develops its hunting skills and gains the abilities required in adulthood and independence through dispersal. Little is known however, about this stage in the lives of raptors such as harpy eagles, Harpia harpyja. Between March 2016 and July 2017, we recorded three predation attempts on groups of primates by a wild juvenile harpy eagle in southwestern Brazilian Amazonia, including the first predation of an adult squirrel monkey, Saimiri ustus. These sequential records give insights into the gradual development of hunting skills during the post-fledging period, similar to what has been reported for other birds of prey. We hypothesize that a link between developing flight skills, decreasing parental food provisioning and increasingly successful captures triggers adulthood and independence in harpy eagles. (AU)

O período pós-emplumagem é de suma importância para os rapinantes, pois é quando um jovem desenvolve a habilidade de caça necessária na idade adulta e a independência por meio da dispersão. Entretanto, pouco se sabe sobre esse estágio na vida de rapinantes como o gavião-real, Harpia harpyja. Entre março 2016 e julho 2017, três tentativas de predação sobre grupos de primatas por um gavião-real juvenil foram registradas no sudoeste da Amazônia brasileira, incluindo a primeira predação de um macaco-de-cheiro adulto, Saimiri ustus. Estes registros sequenciais indicam um desenvolvimento gradual da habilidade de caça ao longo do período de pós-emplumagem, de forma similar ao relatado para outros rapinantes. Hipotetizamos que a associação entre o desenvolvimento da habilidade de voo, diminuição do provisionamento pelos pais e aumento da taxa de capturas bem-sucedidas promove a maturidade e independência no gavião-real.(AU)

Schirmer’s Test I and determination of intraocular pressure in healthy common buzzards (Buteo buteo)

Background: The structure of the eye in wild birds is 45% larger than that in humans, which provides excellent visualcapacity but also makes them vulnerable to eye trauma. Trauma, neoplasia, infectious diseases of the ocular surface, uveitis,glaucoma, and corneal diseases in wild birds, but mainly trauma, can cause a reduction in their tear production; therefore,determining the amount of tear production in the wild birds is very important. Studies have shown that the results of theSchirmer’s tear test (STT) and intraocular pressure (IOP) values differ among wild bird species, and that both anesthesiaand sedation affects these parameters. The main objective of the present study was to determined IOP and STT I values inhealthy common buzzards (Buteo buteo).Materials, Methods & Results: Thirty healthy common buzzards were selected for the study following clinical and ophthalmic examinations. Following physical and clinical examinations of all subjects, routine ophthalmologic examinationswere conducted, including reflex examinations (pupillary, palpebral, menace, dazzle) and direct ophthalmoscopy for theeyelids, conjunctiva, cornea, iris, lens, and fundus. All examinations were conducted without anesthesia or sedation whilethe birds were in the dorsal recumbent position, and the results of STT I and IOP were recorded. Both tests were repeatedfor the right and left eyes. The mean ± SE STT I values for the right and left eyes were 12.63 ± 0.51 and 12.43 ± 0.54mm/min, respectively. A comparison between STT I values of the right and left eyes revealed no statistically significantdifferences (P > 0.620). The means and ranges of the TonoVet® IOP results for the right and left eyes were 32.06 ± 1.58and 32.60 ± 1.51 mmHg, respectively. There was no statistically significant...

Schirmers Test I and determination of intraocular pressure in healthy common buzzards (Buteo buteo)

Background: The structure of the eye in wild birds is 45% larger than that in humans, which provides excellent visualcapacity but also makes them vulnerable to eye trauma. Trauma, neoplasia, infectious diseases of the ocular surface, uveitis,glaucoma, and corneal diseases in wild birds, but mainly trauma, can cause a reduction in their tear production; therefore,determining the amount of tear production in the wild birds is very important. Studies have shown that the results of theSchirmers tear test (STT) and intraocular pressure (IOP) values differ among wild bird species, and that both anesthesiaand sedation affects these parameters. The main objective of the present study was to determined IOP and STT I values inhealthy common buzzards (Buteo buteo).Materials, Methods & Results: Thirty healthy common buzzards were selected for the study following clinical and ophthalmic examinations. Following physical and clinical examinations of all subjects, routine ophthalmologic examinationswere conducted, including reflex examinations (pupillary, palpebral, menace, dazzle) and direct ophthalmoscopy for theeyelids, conjunctiva, cornea, iris, lens, and fundus. All examinations were conducted without anesthesia or sedation whilethe birds were in the dorsal recumbent position, and the results of STT I and IOP were recorded. Both tests were repeatedfor the right and left eyes. The mean ± SE STT I values for the right and left eyes were 12.63 ± 0.51 and 12.43 ± 0.54mm/min, respectively. A comparison between STT I values of the right and left eyes revealed no statistically significantdifferences (P > 0.620). The means and ranges of the TonoVet® IOP results for the right and left eyes were 32.06 ± 1.58and 32.60 ± 1.51 mmHg, respectively. There was no statistically significant...(AU)

Foraging activity of the snail kite, Rostrhamus sociabilis (Aves: Accipitridae) in wetlands of southern Brazil / Atividade de forrageio de gavião-caramujeiro, Rostrhamus sociabilis (Aves: Accipitridae) em áreas úmidas do sul do Brasil

The snail kite (Rostrhamus sociabilis) is widely distributed in the American continent. Its specialised diet consists mostly of the gastropod mollusk Pomacea sp and its foraging strategy probably varies depending on the season, prey availability, and climate factors, which can be reflected in its semi-nomad behaviour. This study was aimed at examining the hunting strategy of the snail kite, and its association with climate factors and habitat heterogeneity. Direct observations of birds between January 2010 and March 2011 in southernmost Brazil revealed that hunting was still the predominant foraging strategy (79% of records) to capture mollusks. Despite morphological specialisations to extract mollusks from the shells, the handling time (average = 92.4 s) was twice as much the time between prey search and capture (average = 55 s). The increase in the number of mollusks ingested apparently occurs when the resting time on perches or any other substrates near the hunting sites decreases between successive unsuccessful attempts. The correlation between the number of consumed preys and the climatic variables examined was low. Regarding habitat heterogeneity, our findings suggest that birds forage preferentially in marshes with low vegetation, which may increase the access to mollusks. The hunting efficiency of the snail kite was high (76 % successful attempts) compared to those of other birds of prey.(AU)

O gavião-caramujeiro (Rostrhamus sociabilis) possui ampla distribuição no continente americano e apresenta dieta especializada no molusco gastrópode Pomacea sp. Possivelmente, a estratégia de forrageio da espécie responde às variações sazonais na disponibilidade de presas, bem como aos fatores climáticos, o que pode refletir em seu comportamento seminômade. O objetivo desse estudo foi avaliar a estratégia de caça do gavião-caramujeiro, buscando suas associações quanto aos aspectos climáticos e à heterogeneidade do habitat. Observações diretas das aves, feitas entre janeiro de 2010 e março de 2011 no extremo sul brasileiro, revelaram que, para a captura dos moluscos, as aves usaram predominantemente a estratégia de caça do tipo still hunting (79% dos registros). Apesar de apresentar especializações morfológicas para a extração dos moluscos da concha, a avaliação do tempo empregado na manipulação (média = 92,4 s) foi quase o dobro do desprendido entre a procura e a captura (média = 55 s) das presas. Aparentemente, o aumento no número de moluscos ingeridos ocorre por meio de redução no tempo de repouso entre sucessivas investidas de captura mal sucedidas, tal como pelo uso de poleiros ou quaisquer outros substratos próximos aos locais de captura. O número de presas consumidas apresenta baixa relação com as variáveis climáticas testadas. Quanto à heterogeneidade do habitat, os dados sugerem que as aves forrageiam preferencialmente em banhados com cobertura vegetal rasteira, o que poderia aumentar a acessibilidade aos moluscos. O gavião-caramujeiro apresentou alta taxa de eficiência de caça (76% das investidas tiveram êxito), revelando a eficiência da estratégia de caça desta ave quando comparada a outras aves de rapina.(AU)