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[en] A series of radio-controlled glider models was constructed by duplicating the aerodynamic shape of soaring birds (raven, turkey vulture, seagull and pelican). Controlled tests were conducted to determine the level of longitudinal and lateral-directional static stability, and to identify the characteristics that allowed flight without a vertical tail. The use of tail-tilt for controlling small bank-angle changes, as observed in soaring birds, was verified. Subsequent tests, using wing-tip ailerons, inferred that birds use a three-dimensional flow pattern around the wing tip (wing tip vortices) to control adverse yaw and to create a small amount of forward thrust in gliding flight.
[en] The common guillemot, Uria aalge, a member of the auk family of seabirds exhibits locomotive capabilities in both aerial and aquatic substrates. Simplistic forms of this ability have yet to be achieved by robotic vehicle designs and offer significant potential as inspiration for future concept designs. In this investigation, we initially investigate the power requirements of the guillemot associated with different modes of locomotion, empirically determining the saving associated with the retraction of the wing during aquatic operations. A numerical model of a morphing wing is then created to allow power requirements to be determined for different wing orientations, taking into account the complex kinematic and inertial dynamics associated with the motion. Validation of the numerical model is achieved by comparisons with the actual behaviour of the guillemot, which is done by considering specific mission tasks, where by the optimal solutions are found utilizing an evolutionary algorithm, which are found to be in close agreement with the biological case.
[en] The white stork, Ciconia ciconia, is a model species for studies of bird migration and behavior, but previously published genetic markers are not informative enough to perform individual–based genetic studies. Following discovery using next generation sequencing, 11 polymorphic markers were selected and tested in samples from two study sites. The number of alleles per locus ranged from 2–10 with an average of 5.3. The mean observed and expected heterozygosities were 0.519 and 0.565 respectively. PID was adequately sensitive for population– and individual–based genetics studies. There was no significant evidence of allelic drop–out, null alleles, or other errors; one sample site deviated from Hardy–Weinberg equilibrium for two loci, but no loci deviated in both samples, suggesting utility of these markers. These markers can be used to answer a range of ecological questions including those related to genetic diversity, degree of natal philopatry, and genetic mating strategies. (Author)
[en] Thermal soaring saves much energy, but flying large distances in this form represents a great challenge for birds, people and unmanned aerial vehicles (UAVs). The solution is to make use of the so-called thermals, which are localized, warmer regions in the atmosphere moving upward with a speed exceeding the descent rate of birds and planes. Saving energy by exploiting the environment more efficiently is an important possibility for autonomous UAVs as well. Successful control strategies have been developed recently for UAVs in simulations and in real applications. This paper first presents an overview of our knowledge of the soaring flight and strategy of birds, followed by a discussion of control strategies that have been developed for soaring UAVs both in simulations and applications on real platforms. To improve the accuracy of the simulation of thermal exploitation strategies we propose a method to take into account the effect of turbulence. Finally, we propose a new GPS-independent control strategy for exploiting thermal updrafts.
[en] The Yellow-vented Bulbul (Pycnonotus goiavier) is one of the most sighted birds in oil palm plantation. A study on their dietary habits was conducted at the Durafarm Oil Palm Plantation from February 2011 to May 2013 to determine the reason behind their abundance. In this study, 45 individuals of P. goiavier were dissected for stomach content analysis. Ivlev's electivity index (E) was used to measure the degree of food selection by P. goiavier. The results showed that this bird species mainly selected the Order Coleoptera (mostly pollinating weevil) (E= +0.97) and Homoptera (E= +0.87) as their main food sources in the oil palm plantation. This bird also selected Order Diptera (E= -0.30), Hemiptera (E= -0.43) and Hymenoptera (E= -0.92) as a prey based on their abundance. However, this species mainly avoided feeding on insects from Order Odonata, Orthoptera, Dictyoptera and Lepidoptera (E=-1.0 each) in oil palm plantation. There is a weak negative correlation found for the distribution of P. goiavier with the abundance of insects in oil palm plantation. Further investigation is needed on this bird species towards predating the oil palm pollinating weevil, since it could possibly affect the population density of the pollinating weevil and subsequently the oil palm fruit set. (author)
[en] Fledgling production has often been used as an estimator of avian reproductive success, and it is conditioned by factors affecting offspring development and/or survival during the nesting period. We aimed to determine which predictors influenced fledgling output among a set of basic breeding parameters and local temperature data collected over 25 years in a Mediterranean great tit, Parus major, population, using an information–theoretic approach for model selection. Of the studied variables, the number of hatchlings per nest was the single–most important predictor influencing fledgling production, with larger broods eventually yielding more fledglings, although mass prior to fledging may have been compromised. This result suggests an overall good adjustment between brood size and resource availability in the studied population. (Author)
[en] We studied the breeding success of two seabird species, the blue–footed booby, Sula nebouxii, and the brown booby, Sula leucogaster, in relation to touristic disturbance in order to focus conservation management strategies in the protected area of the Marietas Islands in Bahía de Banderas, Mexico. Data were collected throughout the breeding season of 2013 at Isla Larga. We considered three sites under different conditions of simulated disturbance within the colonies: ‘medium’, visits constrained to a single path; ‘high’, visits without spatial restrictions, and ‘low’, no visits. The total numbers of nests, eggs and chicks for each species were recorded weekly at the three sites. On the basis of these data, we determined the viability of eggs (hatching success) and chicks. A generalized linear mixed model (GLIMMIX) showed that breeding success (eggs–to–fledglings rate) had no relationship to the conditions of the area and but was significantly lower in the blue–footed booby. The presence of tourists, as measured in this study, was not the cause of nesting failure. Other, non–evaluated factors likely play a role in limiting the breeding success of the two species of booby studied here. (Author)
[en] The purpose of this study was to provide a reference for xeroradiographic and conventional radiographic anatomy of the bobwhite quail (Colinus virginianus) as a representative of the avian order Galliformes. The heads, bodies, wings, and pelvic limbs of four adult birds were radiographed using xeroradiographic and conventional radiographic techniques. Nine xeroradiographs and their corresponding conventional radiographs were selected, and the xeroradiographs labeled to illustrate the normal anatomy of these regions. A xeroradiograph of the tarsometatarsus of the domestic peacock (Pavo cristatus) was also included to demonstrate the metatarsal spur, which is not present in the quail
[en] Two styles of bird locomotion, hovering and intermittent flight, have great potential to inform future development of autonomous flying vehicles. Hummingbirds are the smallest flying vertebrates, and they are the only birds that can sustain hovering. Their ability to hover is due to their small size, high wingbeat frequency, relatively large margin of mass-specific power available for flight and a suite of anatomical features that include proportionally massive major flight muscles (pectoralis and supracoracoideus) and wing anatomy that enables them to leave their wings extended yet turned over (supinated) during upstroke so that they can generate lift to support their weight. Hummingbirds generate three times more lift during downstroke compared with upstroke, with the disparity due to wing twist during upstroke. Much like insects, hummingbirds exploit unsteady mechanisms during hovering including delayed stall during wing translation that is manifest as a leading-edge vortex (LEV) on the wing and rotational circulation at the end of each half stroke. Intermittent flight is common in small- and medium-sized birds and consists of pauses during which the wings are flexed (bound) or extended (glide). Flap-bounding appears to be an energy-saving style when flying relatively fast, with the production of lift by the body and tail critical to this saving. Flap-gliding is thought to be less costly than continuous flapping during flight at most speeds. Some species are known to shift from flap-gliding at slow speeds to flap-bounding at fast speeds, but there is an upper size limit for the ability to bound (∼0.3 kg) and small birds with rounded wings do not use intermittent glides.