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Wind tunnels allow researchers to investigate animals' flight under controlled conditions, and provide easy access to the animals during flight. These increasingly popular devices can benefit integrative migration biology by allowing us to explore the links between aerodynamic theory and migration as well as the links between flight behavior and physiology. Currently, wind tunnels are being used to investigate many different migratory phenomena, including the relationship between metabolic power and flight speed and carry-over effects between different seasons. Although biotelemetry is also becoming increasingly common, it is unlikely that it will be able to completely supplant wind tunnels because of the difficulty of measuring or varying parameters such as flight speed or temperature in the wild. Wind tunnels and swim tunnels will therefore continue to be important tools we can use for studying integrative migration biology. doi: 10.1093/icb/icq063

Billions of animals migrate each year. To successfully reach their destination, migrants must have evolved an appropriate genetic program and suitable developmental, morphological, physiological, biomechanical, behavioral, and life-history traits. Moreover, they must interact successfully with biotic and abiotic factors in their environment. Migration therefore provides an excellent model system in which to address several of the 'grand challenges' in organismal biology. Previous research on migration, however, has often focused on a single aspect of the phenomenon, largely due to methodological, geographical, or financial constraints. Integrative migration biology asks 'big questions' such as how, when, where, and why animals migrate, which can be answered by examining the process from multiple ecological and evolutionary perspectives, incorporating multifaceted knowledge from various other scientific disciplines, and using new technologies and modeling approaches, all within the context of an annual cycle. Adopting an integrative research strategy will provide a better understanding of the interactions between biological levels of organization, of what role migrants play in disease transmission, and of how to conserve migrants and the habitats upon which they depend. doi: 10.1093/icb/icq013

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.05.023 Byline: HA[yen]kan Karlsson (a), Per Henningsson (b), Johan Backman (a), Anders Hedenstrom (b), Thomas Alerstam (a) Abstract: We investigated the orientation in relation to wind of common swifts, Apus apus, during nocturnal spring and autumn migration. Swifts are highly adapted to a life in the air, showing wind-dependent orientation during nocturnal roosting flights, and may be expected to be more efficient in their wind drift/compensation behaviour than nocturnal passerine migrants, which are usually subjected to full or partial wind drift. A tracking radar at Lund in southern Sweden was used to record the orientation of common swifts (identified by their characteristic radar echo signature) on nocturnal migration flights and to measure wind conditions at the altitudes at which the birds were flying. Comparing track and heading directions under easterly and westerly winds revealed that the swifts shifted their heading distinctly into the wind, with the result that track directions were similar under the different wind conditions. As this pattern of complete compensation for drift from cross-winds occurred during both spring and autumn migration, there were no indications of differences between age classes. In addition, we found an effect of side-winds on equivalent airspeeds, with swifts increasing their airspeed with increasing wind speed. Such a response has been theoretically predicted as part of an optimal behaviour for counteracting wind drift but has hereto not been empirically demonstrated. There was also a positive correlation between overall wind speed and equivalent airspeed, making it difficult to interpret whether the swifts respond to the total wind speed rather than specifically to the side-wind effect. Our results suggest that important differences may exist between species in their capacities to orient in relation to the wind and that the swift may be particularly efficient in adjusting heading direction and airspeed to obtain complete compensation for wind drift during high-altitude nocturnal migratory flights. Author Affiliation: (a) Department of Animal Ecology, Lund University, Sweden (b) Department of Theoretical Ecology, Lund University, Sweden Article History: Received 7 December 2009; Revised 4 March 2010; Accepted 17 May 2010 Article Note: (miscellaneous) MS. number: 09-00769R

This paper introduces some theoretical concepts based on optimality theory that may be applied to bat migration. Most predictions are based on flight mechanics and potential flight range. Optimal behavior will depend on the relevant immediate currency, such as safety, time, or energy. Predictions concern optimal flight speeds, stopover duration, fuel load at departure, and the adaptive use of winds. I also consider a criterion for fuel management when bats are migrating between summer and hibernation sites. The overall migration speed is predicted to be 46 km/day for a small (10-g) bat, and banding recoveries in Nathusius's bat (Pipistrellus nathusii) showed a mean speed of 47 km/day. The timing of migration in bats that minimizes the time spent in migration is considered a result of the trade-off between seasonally increased length of the night (decreased in spring) and reduction of aerial insect abundance. Most predictions remains to be tested; the theoretical framework herein offers a point of departure when designing new field or laboratory studies of bat migration. Key words: flight mechanics, flight speed, fuel load, hibernation, migration speed, migration theory

Many bird species migrate long distances without any food intake and must optimize storage of energy with respect to minimization of aerodynamic drag. To contribute to the understanding of this issue, we investigated, by magnetic resonance imaging (MRI), spatial distributions of body fat during the accumulation process before migration. We collected data from 12 Lesser Whitethroats (Sylvia curruca), 9 European Robins (Erithacus rubecula), 8 Blackcaps (Sylvia atricapilla), and 5 Willow Warblers (Phylloscopus trochilus). On average, each bird was examined 3.2 times. Adipose tissue was visualized using T1-weighted spin-echo MRI at 1.5 T. Fat-containing pixels were identified by an image-segmentation procedure. Data were analyzed with respect to (1) fat distribution within the body, (2) relationship between frontal surface area and fat mass increase, (3) fat mass increase in comparison with increase in total body mass, and (4) fat mass in relation to standardized visual classification of fat deposits. Fat increase was reflected by a larger frontal area, though adipose tissue was not deposited equally along the length of the bird. Slices with largest frontal area showed relatively low fractions of fat. Frontal area increased less than expected from conventional geometrical models, which indicates that the body shape is altered. The increase in total body mass was generally higher than the total fat mass increase, which indicates that other tissue, most likely flight muscle, can metabolize rapidly in correlation with fat accumulation. In Blackcap, total fat mass was not linearly related to standardized fat-deposit classes. Key words: adipose tissue, fat storage, fuel load, magnetic resonance imaging, migration, migratory birds. Plusieurs especes d'oiseaux migrent sur de longues distances sans s'alimenter et doivent optimiser l'accumulation d'energie tout en minimisant la trainee aerodynamique. Afin d'ameliorer notre comprehension sur cette question, nous avons etudie, a l'aide de l'imagerie par resonance magnetique (IRM), la repartition spatiale des graisses corporelles au cours du processus d'accumulation precedant la migration. Nous avons recolte des donnees de 12 Sylvia curruca, 9 Erithacus rubecula, 8 Sylvia atricapilla et 5 Phylloscopus trochilus. En moyenne, chaque oiseau etait examine 3,2 fois. Le tissu adipeux etait observe de l'aide d'IRM en sequence spin echo ponderee en T1 a 1,5 T. Les pixels correspondant aux graisses etaient identifies par une procedure de segmentation des images. Les donnees etaient analysees relativement h (1) la distribution des graisses dans le corps, (2) la relation entre la superficie frontale et l'augmentation de la masse adipeuse, (3) l'augmentation de la masse adipeuse comparativement a l'augmentation de la masse corporelle totale et (4) la masse adipeuse en fonction de la classification visuelle standardisee des depots adipeux. L'augmentation des graisses se refletait par une plus grosse superficie frontale, bien que le tissu adipeux ne se soit pas depose egalement tout le long de l'oiseau. Les tranches avec de plus grosses superficies frontales presentaient des proportions de graisses relativement faibles. La superficie frontale a moins augmente que prevu selon les modales geometriques conventionnels, lesquels indiquent que la forme du corps est alteree. L'augmentation de la masse corporelle totale etait generalement plus importante que l'augmentation de la masse adipeuse totale, ce qui indique que d'autres tissus, probablement des muscles de vol, peuvent metaboliser rapidement en correlation avec l'accumulation de graisses. Chez S. atricapilla, la masse adipeuse totale n'etait pas reliee lineairement aux classes standardisees de depot adipeux.

Birds can save distance and time on their migratory journeys by following great circles rather than rhumblines, but great-circle routes require more complex orientation with changing courses. Flight directions at different places along the route and in relation to the destination can be used to test whether birds migrate along great circles or rhumblines. Such data have indicated great-circle migration among shorebirds at high latitudes, but no critical tests have been made for passerines. Using tracking radar on board the icebreaker Oden in August 2005, we recorded westerly flight directions of passerine migrants over the Chukchi Sea. The main sector of migratory directions was 237-311[degrees] centered on a mean heading direction of 274[degrees]. The most likely species to participate in this westward trans-Beringia migration, mainly departing from Alaska, were Eastern Yellow Wagtail (Motacilla tschutschensis), Arctic Warbler (Phylloscopus borealis kennicotti), Northern Wheatear (Oenanthe oenanthe), and Bluethroat (Luscinia svecica); all except the Bluethroat were recorded from the ship. Observed flight directions agreed with predicted great-circle courses but not with rhumbline courses for three of these four species with winter quarters in Southeast Asia; no definite conclusion could be drawn for the Northern Wheatear (wintering in East Africa). These results support great-circle migration among passerines traveling between Alaska and Old World winter quarters, though the long-distance precision and orientation mechanisms are still unknown. The relative importance of different evolutionary causes--such as circumvention of geographic barriers, retracing of ancient colonization ways, or distance reduction by great-circle migration--to complex bird migration routes with changing courses remains to be understood. Key words: Arctic birds, bird migration, great-circle orientation, trans-Beringia migration. Les oiseaux peuvent reduire la distance et la duree de leurs periples migratoires en suivant une orthodromie plutot qu'une loxodromie. Cependant, les orthodromies requierent une orientation plus complexe lors des changements de cap. Les directions de vol en differents points du trajet migratoire peuvent etre utilisees pour evaluer si les oiseaux migrent le long d'orthodromies ou de loxodromies. De telles donnees ont devoile des migrations par orthodromie chez les oiseaux de rivage a de hautes latitudes mais aucun test decisif n'a ete mene pour les passereaux. A. l'aide d'un radar du brise-glace Oden, nous avons enregistre les directions de vol vers l'ouest des passereaux migrant au-dessus de la roer de Chukchi en aout 2005. Le principal secteur de directions migratoires etait 237-311[grados], centre sur un azimut moyen de 274[grados]. Les especes les plus susceptibles de realiser cette migration trans-Beringie vers l'ouest, principalement a partir de l'Alaska, etaient Motacilla tschutschensis, Phylloscopus borealis kennicotti, Oenanthe oenanthe et Luscinia svecica. Toutes ces especes, a l'exception de L. svecica, ont ete observees a partir du bateau. Les directions de vol observees correspondaient aux trajectoires orthodromiques predites et non aux trajectoires loxodromiques pour trois de ces quatre especes ayant leurs quartiers d'hiver dans le sud-est de l'Asie; aucune conclusion nette n'a pu etre tiree pour O. oenanthe (qui hiverne en Afrique de l'Est). Ces resultats supportent l'hypothese de migration par orthodromie chez les passereaux qui voyagent entre l'Alaska et les quartiers d'hiver de l'Ancien Monde, bien que la precision sur de longues distances et les mecanismes d'orientation demeurent inconnus. L'importance de differentes causes d'evolution--tel que le contournement des barrieres geographiques, la reconstitution d'anciennes voies de colonisation ou la reduction de la distance migratoire en suivant une orthodromie--relativement aux roles migratoires complexes comportant des trajectoires changeantes reste a etre comprise.

Migratory animals show a suite of adaptations to cope with their journeys. These include not only morphological features for efficient locomotion and storage of energy but also behavioral adjustments to [...]

Eleonora's Falcon (Falco eleonorae) breeds in the Mediterranean region and is highly adapted for catching small birds on passage migration between Eurasia and their African winter quarters, which they feed their young. We studied gliding flight behavior of Eleonora's Falcon at a breeding colony located on a small island southwest of Sardinia, Italy. Gliding and soaring flight performance was measured using an optical range finder and evaluated against flight mechanical theory. The male falcon does the majority of hunting and usually sets off from the colony to hunting areas located at high altitude over the open sea to catch prey. To lower the cost of transport and maximize the energy gain from hunting, we show that the birds use vertical winds for soaring when available. The occurrence of rising air changes with wind direction. At north-north-westerly winds (on-shore), slope lift is available outside the nesting cliffs, and at south-southeasterly winds thermals that form over the island drift out over the sea. Our observations demonstrated the flexibility of flight behavior in relation to the wind situation, and birds thereby make full use of available soaring conditions.

ABSTRACT. Bird migration was recorded by tracking radar and visual observation at 23 sites in the region of the Northwest Passage, between Baffin Island and Herschel Island in the Beaufort [...]

(Received 8 August 1997; accepted in revised form 19 January 1998) 1 Department of Animal Ecology, Lund University, Ecology Building, S-223 62 Lund, Sweden; anders.hedenstrom@zooekol.lu.se ABSTRACT. I report here for [...]

Predictions of optimal climb rate up to the cruising altitude for knots, Calidris canutus, and turnstones, Arenaria interpres, agree with the observational data of these species. Disturbed air, resulting from orographic wind effects, causes the birds' failure to exhibit a negative relationship between airspeed and climb rate. Shorebirds exhibit the ability to identify and exploit lift while climbing.

A state-dependent optimal annual routine model that incorporates explicit density dependence in the food supply is developed to study the optimal moult strategies. The results suggest that the sequence of moult might be an adaptive response to the problem of optimal timing of moult of differing feathers within the same feather tract.

A study of the effect of density dependence and winter climate on the observed fluctuations of population dynamics using annual variation in the North Atlantic Oscillation as an index of winter climate on 17 bird species. The study suggests that the winter climate affects the population rate of change in migratory birds, however climate variation may affect species differently, between as well as within geographical areas.

Flight directions of birds migrating at high geographic and magnetic latitudes can be used to test bird orientation by celestial or geomagnetic compass systems under polar conditions. Migration patterns of arctic shorebirds, revealed by tracking radar studies during an icebreaker expedition along the Northwest Passage in 1999, support predicted sun compass trajectories but cannot be reconciled with orientation along either geographic or magnetic [oxodromes (rhumb lines). Sun compass routes are similar to orthodromes (great circle routes) at high latitudes, showing changing geographic courses as the birds traverse longitudes and their internal clock gets out of phase with local time. These routes bring the shorebirds from high arctic Canada to the east coast of North America, from which they make transoceanic flights to South America. The observations are also consistent with a migration link between Siberia and the Beaufort Sea region by way of sun compass routes across the Arctic Ocean., How birds use different compass systems based on the sun, stars, and geomagnetic field to orient along their migration routes is not fully understood (1-4). The region at the Northwest [...]

Studies field estimates of body drag coefficient on the basis of dives in passerine birds. Measurement of the maximum dive speeds of passerine birds during spring migration; Estimation of the potential migratory flight range and characteristic flight speeds of birds; Wind tunnel measurements on dead, frozen bird bodies.

Examines the gliding flight performance of a jackdaw, Corvus monedula in a wind tunnel. Measurement of glide super-polar; Theory of gliding flight; Calculation of wingspan and wing area with respect to forward speed in gliding birds.

Discusses a study which observed a swallow flying in the Lund wind tunnel from the side and from behind using synchronised high-speed video cameras. Account of related studies; Materials and methods; Results and discussion.

Focuses on a study which analyzed the flight performance of Eleonora's falcon, a species breeding in the Mediterranean region during hunting excursions. Background information on the speed of flight performance of falcons; Materials and methods; Results; Discussion.

Presents a study on the effects of moult gap size or area reduction in birds' wings on their aerodynamic performance. Methodology used; Results and discussion; Conclusion.

Comments on a study about the effects of wind direction on the ground speed of birds. Flight costs; Importance of wind in shaping migration decisions; Conclusions.

Sleep is a universal and complex state and it is widely agreed that this state is present in every animal species. However, the evolutionary origins of sleep remain ignored or misunderstood, which has led researchers to study, in various species, this common behaviour of all living organisms. Sleep is commonly studied at various levels under laboratory conditions, using tethered devices which record electroencephalographic or electromyographic readings. These artificial settings tend to induce stress, reduce animal freedom and prevent the use of sleeping shelters. In this paper, we present a novel, implantable instrumentation for a complete characterization of sleep under natural conditions suitable for a wide range of animal species, even for animals as small as pigeons or mice. Several configurations of this system are possible to enable the measurement of up to 16 electrophysiology channels, 3 temperature channels as well as 3-axes accelerometry. With an embedded flash memory card for the storage of data collected, the system can be used as a datalogger for the recording of signals in the field.