RESUMO

The American barn owl is a nocturnal bird of prey in which hind limb movements are a key factor in obtaining food; however, the architectural properties of its hind limb muscles have not been studied. This study sought to identify functional trends in the Tyto furcata hindlimb muscles by studying muscular architecture. The architectural parameters of the selected hip, knee, ankle, and digit muscles were studied in three specimens of the Tyto furcata and joint muscular proportions with an additional dataset were calculated. Previously published information on Asio otus was used for comparison. The flexor muscles of the digits had the highest muscle mass. Regarding architectural parameters, the main flexor of the digits (flexor digitorum longus) and the muscles that extend the knee and ankle joints (femorotibialis and gastrocnemius) showed a high physiological cross-sectional area (PCSA) and short fibers, allowing powerful digit flexion and knee and ankle extension. These mentioned features are in accordance with hunting behavior, in which prey capture is not only closely linked to the flexion of the digits but also to the movements of the ankle. During hunting, the distal hind limb is flexed and then fully extended at the moment of contact with the prey, whereas the digits are close to grasping the prey. The hip muscles showed a predominance of extensors over flexors, which were more massive, with parallel fibers and without tendons or short fibers. These features lead to a higher capacity to generate velocity to the detriment of forces, as indicated by the high values of the architectural index, their relatively low PCSA, and short or intermediate fiber length, which enhance the control of the joint positions and muscle length. Compared to Asio otus, Tyto furcata showed longer fibers; however, the relationship between fiber length and PCSA was similar for both species.

Assuntos

RESUMO

After reviewing the systematics and distribution of the living and fossil small West Indian taxa of Tytonidae (Tyto), we reached the following conclusions: (1) Strix tuidara J. E. Gray, 1827, type locality of Brazil, is the earliest available and correct name to be used in a binomen for New World mainland barn owls; (2) the North American mainland subspecies Tyto tuidara pratincola (Bonaparte, 1838), new combination, is resident in the Bahamas ("Tyto perlatus lucayanus" Riley, 1913, is a synonym), where it probably did not colonize until after the European introduction of Rattus Fischer, in Hispaniola (Dominican Republic and Haiti) where it became established in the 20th century, and subsequently in Puerto Rico; (3) Tyto furcata (Temminck, 1827) of Cuba, Jamaica and the Cayman Islands is a different species restricted to its insular distribution, with "T. alba niveicauda" Parkes Phillips, 1978, of the Isle of Pines (now Isla de la Juventud) as a synonym; (4) the distinct species Tyto glaucops (Kaup, 1852), now endemic to Hispaniola, once occurred in Puerto Rico, as the fossil species "T. cavatica" Wetmore, 1920, is here shown to be a synonym; (5) the smallest taxon Tyto insularis (Pelzeln, 1872) of the southern Lesser Antilles is treated as a separate species, in which the nominate subspecies T. i. insularis (St. Vincent, Grenada, and the Grenadines) differs slightly but consistently in coloration from T. i. nigrescens (Lawrence, 1878) of Dominica; (6) another barn owl, Tyto maniola, new species, of this group of small tytonids from the West Indies inhabited Cuba during part of the Quaternary, and is here named and described.

Assuntos

RESUMO

Barn Owls (Tytonidae) are nocturnal raptors with the largest geographical distribution among Strigiformes. Several osteological, morphometrical, and biomechanical studies of this species were performed by previous authors. Nevertheless, the myology of forelimb and tail of the Barn Owls is virtually unknown. This study is the first detailed myological study performed on the wing and tail of the American Barn Owl (Tyto furcata). A total of 11 specimens were dissected and their morphology and muscle masses were described. Although T. furcata has the wing and tail myological pattern present in other species of Strigiformes, some peculiarities were observed including a difference in the attachment of m. pectoralis propatagialis due to the lack of the os prominence, and the presence of an osseous arch in the radius that seems to widen the anchorage area of the mm. pronator profundus, extensor longus alulae, and extensor longus digiti majoris. Furthermore, the m. biceps brachii has an unusual extra belly that flexes the forearm. The interosseous muscles have a small size and lacks ossified tendons. This feature may be indicative of a lower specialization in the elevation and flexion of the digiti majoris. Forelimb and tail muscle mass account for 10.66 and 0.24% of the total body mass, respectively. Forelimb muscle mass value is similar to the nocturnal (Strigiformes) and diurnal (Falconidae and Accipitridae) raptors, while the tail value is lower than in the diurnal raptors (Falconidae and Accipitridae). The myological differences with other birds of prey are here interpreted in association with their "parachuting" hunting style. This work complements our knowledge of the axial musculature of the American Barn owls, and provides important information for future studies related to functional morphology and ecomorphology.

Assuntos

RESUMO

Com o objetivo de estudar descritiva e topograficamente os tratos e aptérios, torácicos e abdominais, em Suindara (Tyto alba, Scopoli 1769), foram utilizadas 15 aves adultas (06 machos e 09 fêmeas), pesando em média 430 g, doadas por óbito pela Superintendência do Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais – IBAMA em Pernambuco. As aves foram fixadas mediante a aplicação subcutânea, intramuscular e intracavitária de solução aquosa de formaldeído a 10% e imersas na mesma solução por 48 horas. Em seguida, com auxílio de instrumentos cirúrgicos, as penas constantes nas regiões ventral, laterais e dorsal do tronco foram seccionadas próximo ao folículo, deixando de 0,2 a 0,3 cm do raque para melhor visualização e registro dos tratos e aptérios. Utilizou-se como padrão morfológico comparativo, a espécie Gallus gallus domesticus. O estudo mostrou que os tratos e aptérios possuem limites adversos, podendo ser menores ou maiores que as regiões os quais estão localizados. Além dos descritos para o padrão comparativo, foram identificados um trato e quatro aptérios (trato umeral ventral, aptério umeral cranial, aptério interescapular, aptério abdominal ventral e aptério abdominal lateral) os quais foram denominados e descritos de acordo com as relações anatômicas. Os tratos peitoral e esternal são unidos cranialmente e caudalmente, conferindo ao aptério peitoral uma conformação semilunar. O aptério lateral do corpo é dividido pelo trato lateral do corpo em duas partes, cranial e caudal. O aptério esternal, cranialmente não se comunica com outros aptérios e, caudalmente, continua-se como aptério abdominal ventral. Os tratos abdominais lateral e medial são delicados e apresentaram diferenças morfológicas na quantidade de fileiras de penas em relação ao sexo, sendo o lateral mais desenvolvido nos machos e o medial mais desenvolvido nas fêmeas. Mesmo pertencendo a ordem diferente, a Tyto alba apresenta tratos e aptérios com semelhanças morfológicas (forma, dimensão e relações de sintopia) aos da Gallus gallus domesticus, como também aspectos anatômicos particulares que caracterizam seu padrão morfológico além de auxiliar na identificação sexual da espécie.

In order to study the topographical and descriptive thoracic and abdominal tracts and apteria in barn owls (Tyto alba, Scopoli 1769), 15 adult birds (06 males and 09 females), weighing 430g on average, donated after death by the Superintendent of the Brazilian Institute of Environmental and Natural Resources - IBAMA located in Pernambuco, were used. The birds were fixed by subcutaneous, intramuscular and intracavitary infusion of a 10% formaldehyde solution and immersed in the same solution for 48 hours. Afterwards, with the aid of surgical instruments, the feathers from the ventral, lateral and dorsal trunk regions were sectioned near the follicle, leaving 0.2 to 0.3 cm from the rack for easier visualization and recording of tracts and apteria. The Gallus gallus domesticus species was used for comparative morphology. The study showed that tracts and apteria presented undefined limits which may be smaller or larger than the regions where they are located. In addition to the tracts and apteria described in the comparative standard study, others were found (ventral humeral tract, cranial humeral apterium, interscapular apterium, ventral abdominal apterium, lateral and abdominal apteria and dorsopelvic apterium) which were analyzed, named and described according to their anatomical relations. It was observed that the pectoral and sternal tracts are attached cranially and caudally, giving the pectoral apterium a crescent-shaped conformation. The lateral body apterium is divided by the body´s lateral tract into two side parts, cranial and caudal. The sternal apterium does not communicate with other apteria cranially, but caudally, it extends as the ventral abdominal apterium. The lateral and medial abdominal tracts are delicate and showed morphological differences in the number of rows of feathers related to sex, being the lateral more developed in males and the medial more developed in females. Even though they belong to a different order, the Tyto alba species presents morphologically similar apteria (shape, size and syntopy relations) to the Gallus gallus domesticus species, as well as anatomical features that characterize their particular morphology and help in identifying sexual species.

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