Automatic aeroelastic devices in the wings of a steppe eagle Aquila nipalensis. (17/44)

Here we analyse aeroelastic devices in the wings of a steppe eagle Aquila nipalensis during manoeuvres. Chaotic deflections of the upperwing coverts observed using video cameras carried by the bird (50 frames s(-1)) indicate trailing-edge separation but attached flow near the leading edge during flapping and gust response, and completely stalled flows upon landing. The underwing coverts deflect automatically along the leading edge at high angle of attack. We use high-speed digital video (500 frames s(-1)) to analyse these deflections in greater detail during perching sequences indoors and outdoors. Outdoor perching sequences usually follow a stereotyped three-phase sequence comprising a glide, pitch-up manoeuvre and deep stall. During deep stall, the spread-eagled bird has aerodynamics reminiscent of a cross-parachute. Deployment of the underwing coverts is closely phased with wing sweeping during the pitch-up manoeuvre, and is accompanied by alula protraction. Surprisingly, active alula protraction is preceded by passive peeling from its tip. Indoor flights follow a stereotyped flapping perching sequence, with deployment of the underwing coverts closely phased with alula protraction and the end of the downstroke. We propose that the underwing coverts operate as an automatic high-lift device, analogous to a Kruger flap. We suggest that the alula operates as a strake, promoting formation of a leading-edge vortex on the swept hand-wing when the arm-wing is completely stalled, and hypothesise that its active protraction is stimulated by its initial passive deflection. These aeroelastic devices appear to be used for flow control to enhance unsteady manoeuvres, and may also provide sensory feedback.  (+info)

The traditional knowledge on stingless bees (Apidae: Meliponina) used by the Enawene-Nawe tribe in western Brazil. (18/44)

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Predation increases acoustic complexity in primate alarm calls. (19/44)

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Does the order of invasive species removal matter? The case of the eagle and the pig. (20/44)

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The feasibility of using high resolution genome sequencing of influenza A viruses to detect mixed infections and quasispecies. (21/44)

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It's not too late for the harpy eagle (Harpia harpyja): high levels of genetic diversity and differentiation can fuel conservation programs. (22/44)

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Characterization of H5N1 highly pathogenic avian influenza virus isolated from a mountain hawk eagle in Japan. (23/44)

On January 4, 2007, an emaciated mountain hawk-eagle was found in Kumamoto Prefecture, Japan. Highly pathogenic avian influenza (HPAI) virus subtype H5N1 was isolated from both tracheal and cloacal swabs of the dead bird. On January 13, an outbreak of HPAI, caused by H5N1 strain, occurred in a chicken farm in Miyazaki Prefecture. Within three weeks, three additional outbreaks had occurred (two in Miyazaki Prefecture and one in Okayama Prefecture). To investigate the relationship between the hawk-eagle isolate and chicken isolates, we studied the virus growth, pathogenicity, and phylogenetic information of this hawk-eagle isolate. The highest virus titer was found in the brain (10(7.25 )EID(50)/g), followed by trachea and muscle (10(2.65) and 10(2.50) EID(50)/g, respectively). Sequence analysis at the hemagglutinin (HA) cleavage site of this isolate revealed a typical virulent-type sequence, R-R-R-K-K-R. Phylogenetic analysis demonstrated that the hawk-eagle isolate belongs to Qinghai Lake type virus group. A homology search of the HA gene also showed major similarity (more than 99%) to the Miyazaki and Okayama isolates in 2007 and also Korean isolates in 2006. These results suggest that Qinghai Lake type H5N1 HPAI virus was newly introduced from Asian Continent into Japan, and had already present in natural environment of Kyusyu district in the beginning of January 2007.  (+info)

Natural fatal Sarcocystis falcatula infections in free-ranging eagles in North America. (24/44)

Three bald eagles (Haliaeetus leucocephalus) and 1 golden eagle (Aquila chrysaetos) were admitted to rehabilitation facilities with emaciation, lethargy, and an inability to fly. Intravascular schizonts and merozoites were present in 2 bald eagles, mainly in the lung tissue, whereas the third bald eagle and the golden eagle had lymphohistiocytic encephalitis with intralesional schizonts and merozoites. In all eagles, protozoal tissue cysts were present in skeletal musculature or heart. The protozoal organisms were morphologically compatible with a Sarcocystis sp. By immunohistochemistry, the protozoal merozoites were positive for Sarcocystis falcatula antigen in all cases when using polyclonal antisera. Furthermore, the protozoa were confirmed to be most similar to S. falcatula by polymerase chain reaction in 3 of the 4 cases. To the authors' knowledge, this report presents the first cases of natural infection in eagles with S. falcatula as a cause of mortality.  (+info)