Weather conditions promote route flexibility during open ocean crossing in a long-distance migratory raptor

Weather conditions are paramount in shaping birds’ migratory routes, promoting the evolution of behavioural plasticity and allowing for adaptive decisions on when to depart or stop during migration. Here, we describe and analyze the influence of weather conditions in shaping the sea-crossing stage of the pre-breeding journey made by a long-distance migratory bird, the Eleonora’s falcon (Falco eleonorae), tracked by satellite telemetry from the wintering grounds in the Southern Hemisphere to the breeding sites in the Northern Hemisphere. As far as we know, the data presented here are the first report of repeated oceanic journeys of the same individuals in consecutive years. Our results show inter-annual variability in the routes followed by Eleonora’s falcons when crossing the Strait of Mozambique, between Madagascar and eastern continental Africa. Interestingly, our observations illustrate that individuals show high behavioural plasticity and are able to change their migration route from one year to another in response to weather conditions, thus minimising the risk of long ocean crossing by selecting winds blowing towards Africa for departure and changing the routes to avoid low pressure areas en route. Our results suggest that weather conditions can really act as obstacles during migration, and thus, besides ecological barriers, the migratory behaviour of birds could also be shaped by “meteorological barriers”. We briefly discuss orientation mechanisms used for navigation. Since environmental conditions during migration could cause carry-over effects, we consider that forecasting how global changes of weather patterns will shape the behaviour of migratory birds is of the utmost importance.     

Prevalence of neutralizing antibodies to West Nile virus in Eleonora's Falcons in the Canary Islands

Birds are the major amplifying host for West Nile virus (WNV), a flavivirus that may affect humans and transmitted by bloodsucking vectors. Eleonora's Falcons (Falco eleonorae) migrate to the Canary Islands annually from WNV-endemic regions. To investigate the possible role of Eleonora's Falcons in the circulation of WNV, we measured WNV-specific antibodies in 81 falcons captured in 2006. None of the nestlings but 14.8% of the adults had WNV-neutralizing antibodies. RT-PCR did not detect flaviviruses in nonculicine ectoparasites (n=231) of the falcons. These findings suggest that WNV infection did not occur locally, but rather on the wintering grounds or during migration.     

Satelliten-Telemetrie der Jahreswanderungen eines Wei?storchsCiconia ciconia und Diskussion der Orientierungsmechanismen des Heimzugs

In a female White Stork the complete migration cycle could be tracked by satellite from the nesting site to the wintering grounds in the Sudan and Tanzania and back to the nest. The migration route extended over 16 000 km, autumn migration lasted 100 days, homeward migration 70 days, wintering 58 and 41 days in northeastern and southeastern Africa, respectively. The maximum daily route was about 350 km. Up to Turkey the bird migrated together with its male. Homeward migration was performed within a relatively narrow corridor in which autumn migration took place, but in detail the routes of the two migratory seasons showed substantial differences. These data together with those from some raptors in which complete annual migration cycles could be tracked indicate that homeward migration is based on navigation (vector navigation and/or true navigation) rather than on route reversal.     

Predator versus prey: on aerial hunting and escape strategies in birds

Predator and prey attack-escape performance is likely to bethe outcome of an evolutionary arms race. Predatory birds aretypically larger than their prey, suggesting different flightperformances. We analyze three idealized attack-escape situationsbetween predatory and prey birds: climbing flight escape, horizontalspeeding, and turning and escape by diving. Generally a smallerbird will outclimb a larger predator and hence outclimbing shouldbe a common escape strategy. However, some predators such asthe Eleonora's falcon (Falco elenorae) has a very high rateof climb for its size. Prey species with an equal or highercapacity to climb fast, such as the swift Apus apus, usuallyadopt climbing escape when attacked by Eleonora's falcons.To analyze the outcome of the turning gambit between predatorand prey we use a Howland diagram, where the relative lineartop speeds and minimum turning radii of prey and predator definethe escape and danger zones. Applied to the Eleonora's falconand some potential prey species, this analysis indicates thatthe falcon usually wins against the example prey species; thatis, the prey will be captured. Level maneuvering hunting isthe most common strategy seen in Eleonora's falcons. To avoidcapture via use of this strategy by a predator, the prey shouldbe able to initiate tight turns at high linear speed, whichis facilitated by a low wing loading (weight per unit of wingarea). High diving speed is favored by large size. If close enough to safe cover, a prey might still opt for a verticaldive to escape in spite of lower terminal diving speed thanthat of the predator. On the basis of aerodynamic considerationswe discuss escape flight strategies in birds in relation tomorphological adaptations.     

Age-dependent migration strategy in honey buzzards Pernis apivorus tracked by satellite

Six adult and three juvenile honey buzzards Pernis apivorus were radio-tracked by satellite during autumn migration from southwestern Sweden. All adults crossed the Mediterranean Sea at the Strait of Gibraltar and continued across the Sahara desert to winter in West Africa, from Sierra Leone to Cameroon. Analysing three main steps of the migration, (1) from the breeding site to the southern Mediterranean region, (2) across the Sahara and (3) from the southern Sahara to the wintering sites, the adults changed direction significantly between these steps, and migrated along a distinct large-scale detour. In contrast, the juveniles travelled in more southerly directions, crossed the Mediterranean Sea at various places, but still ended up in the same wintering areas as the adults. Average speeds maintained on travelling days were similar for the two age groups, about 170 km/day in Europe, 270 km/day across Sahara and 125 km/day in Africa south of Sahara. However, as the adults used fewer stopover days en route, they maintained higher mean overall speeds and completed migration in a shorter time (42 days) than the juveniles (64 days). Although the juveniles set out on more direct courses towards the wintering grounds, they did not cover significantly shorter distances than the adults, as they tended to show a larger directional scatter between shorter flight segments. The results corroborate previous suggestions that adult and juvenile honey buzzards follow different routes during autumn migration, and that the birds change migration strategy during their lifetime. While juveniles may use individual vector orientation, social influences and learning may be of great importance for the detour migration of adults. The remarkable and distinct age-dependent shift in migratory route and orientation of the honey buzzard provides a challenging evolutionary problem.     

The trans‐equatorial loop migration system of Eleonora’s falcon: differences in migration patterns between age classes,regions and seasons

Internal factors such as experience (e.g. age) and motivation for breeding, and external ones such as environmental conditions (e.g. meteorology and landscape characteristics) can promote differences in migratory behaviour and routes among seasons, regions and populations. Using satellite telemetry we investigated whether such differences occur and which factors promote them among migrating Eleonora’s falcons breeding in the Mediterranean area (Spain and Croatia) and wintering in Madagascar. We found that during autumn migration no age differences occur when crossing the Sahara desert, but in the remaining African regions, juveniles were more prone than adults to fly at a slower and more tortuous rate, as well as exhibiting longer stop‐overs, particularly in the Sahel region. Such differences might be promoted by a lower foraging and pre‐migratory fattening efficiency in juveniles. During spring, routes were significantly more eastern than during autumn, resulting in a loop migration occurring in all studied populations. This could be accounted by seasonal variation in the distribution of trophic resources. Our results show that Eleonora’s falcons integrate spatially seasonal changing resources on a continental scale throughout their annual cycle, changing their movement patterns in response to internal (age) and external (habitat) factors. This loop migration pattern may prove to be widespread among other Palearctic trans‐continental migratory bird species.     

High juvenile mortality during migration in a declining population of a long‐distance migratory raptor

Many populations of long‐distance migrants are declining and there is increasing evidence that declines may be caused by factors operating outside the breeding season. Among the four vulture species breeding in the western Palaearctic, the species showing the steepest population decline, the Egyptian Vulture Neophron percnopterus, is a long‐distance migrant wintering in Africa. However, the flyways and wintering areas of the species are only known for some populations, and without knowledge of where mortality occurs, effective conservation management is not possible. We tracked 19 juvenile Egyptian Vultures from the declining breeding population on the Balkan Peninsula between 2010 and 2014 to estimate survival and identify important migratory routes and wintering areas for this species. Mortality during the first autumn migration was high (monthly survival probability 0.75) but mortality during migration was exclusively associated with suboptimal navigation. All birds from western breeding areas and three birds from central and eastern breeding areas attempted to fly south over the Mediterranean Sea, but only one in 10 birds survived this route, probably due to stronger tailwind. All eight birds using the migratory route via Turkey and the Middle East successfully completed their first autumn migration. Of 14 individual and environmental variables examined to explain why juvenile birds did or did not successfully complete their first migration, the natal origin of the bird was the most influential. We speculate that in a declining population with fewer experienced adults, an increasing proportion of juvenile birds are forced to migrate without conspecific guidance, leading to high mortality as a consequence of following sub‐optimal migratory routes. Juvenile Egyptian Vultures wintered across a vast range of the Sahel and eastern Africa, and had large movement ranges with core use areas at intermediate elevations in savannah, cropland or desert. Two birds were shot in Africa, where several significant threats exist for vultures at continental scales. Given the broad distribution of the birds and threats, effective conservation in Africa will be challenging and will require long‐term investment. We recommend that in the short term, more efficient conservation could target narrow migration corridors in southern Turkey and the Middle East, and known congregation sites in African wintering areas.     

Satellite tracking of Swedish Ospreys Pandion haliaetus: autumn migration routes and orientation

Autumn migration routes and orientation of Swedish Ospreys Pandion haliaetus were studied by satellite tracking of 18 birds. Of these, 13 could be followed during the entire migration (6 females, 5 males and 2 juveniles). Most birds migrated across western and central Europe to winter in tropical West Africa. However, one juvenile flew to Cameroon and one female used a very easterly route and reached Mozambique. On average, the birds travelled a total distance of about 6700 km, with little variation except for the female wintering in Mozambique, who travelled more than 10 000 km. Of 21 stopovers (of >1 day), only five were made south of 45°N; three of these in Africa. Females departed before males and juveniles and flew to a stopover site they probably were familiar with. After 3–4 weeks there, they continued to their wintering grounds. Also males and juveniles usually made one or more stopovers. Adults seemed to travel to a known wintering site, where they remained stationary, whereas juveniles were more mobile after reaching tropical regions, probably looking for good wintering sites. Males generally left the breeding area in directions similar to the mean migratory direction, whereas a few females departed in diverging initial directions. Apart from these diversions, adult Ospreys followed very straight migratory routes, with overall mean directions of 185–209° and with mean angular deviations of 6–33°. Some juveniles also departed in diverging directions. Moreover, young birds tended to show a larger variability in orientation. Thus, the Ospreys kept a fairly straight direction and did not avoid geographical obstacles such as mountain ranges and desert areas. However, they seemed reluctant to cross large water bodies. There was no correlation between angular deviation and length of the migrational segment, indicating that the principles of orientation by vector summation may not be valid for Osprey migration. Moreover, the geographic direction of migration did not vary in accordance with variations in the magnetic declination, suggesting that the Ospreys did not orient along magnetic loxodromes.     

Around the Mediterranean: an extreme example of loop migration in a long‐distance migratory passerine

An important issue in migration research is how small‐bodied passerines pass over vast geographical barriers; in European–African avian migration, these are represented by the Mediterranean Sea and the Sahara Desert. Eastern (passing eastern Mediterranean), central (passing Apennine Peninsula) and western (via western Mediterranean) major migration flyways are distinguished for European migratory birds. The autumn and spring migration routes may differ (loop migration) and there could be a certain level of individual flexibility in how individuals navigate themselves during a single migration cycle. We used light‐level loggers to map migration routes of barn swallows Hirundo rustica breeding in the centre of a wide putative contact zone between the northeastern and southernwestern European populations that differ in migration flyways utilised and wintering grounds. Our data documented high variation in migration patterns and wintering sites of tracked birds (n = 19 individuals) from a single breeding colony, with evidence for loop migration in all but one of the tracked swallows. In general, two migratory strategies were distinguished. In the first, birds wintering in a belt stretching from southcentral to southern Africa that used an eastern route for both the spring and autumn migration, then shifted their spring migration eastwards (anti‐clockwise loops, n = 12). In the second, birds used an eastern or central route to their wintering grounds in central Africa, shifting the spring migration route westward (clockwise loops, n = 7). In addition, we observed an extremely wide clockwise loop migration encompassing the entire Mediterranean, with one individual utilising both the eastern (autumn) and western (spring) migratory flyway during a single annual migration cycle. Further investigation is needed to ascertain whether clockwise migratory loops encircling the entire Mediterranean also occur other small long‐distance passerine species.     

Migration routes and strategies in a highly aerial migrant, the common swift Apus apus, revealed by light-level geolocators

The tracking of small avian migrants has only recently become possible by the use of small light-level geolocators, allowing the reconstruction of whole migration routes, as well as timing and speed of migration and identification of wintering areas. Such information is crucial for evaluating theories about migration strategies and pinpointing critical areas for migrants of potential conservation value. Here we report data about migration in the common swift, a highly aerial and long-distance migrating species for which only limited information based on ringing recoveries about migration routes and wintering areas is available. Six individuals were successfully tracked throughout a complete migration cycle from Sweden to Africa and back. The autumn migration followed a similar route in all individuals, with an initial southward movement through Europe followed by a more southwest-bound course through Western Sahara to Sub-Saharan stopovers, before a south-eastward approach to the final wintering areas in the Congo basin. After approximately six months at wintering sites, which shifted in three of the individuals, spring migration commenced in late April towards a restricted stopover area in West Africa in all but one individual that migrated directly towards north from the wintering area. The first part of spring migration involved a crossing of the Gulf of Guinea in those individuals that visited West Africa. Spring migration was generally wind assisted within Africa, while through Europe variable or head winds were encountered. The average detour at about 50% could be explained by the existence of key feeding sites and wind patterns. The common swift adopts a mixed fly-and-forage strategy, facilitated by its favourable aerodynamic design allowing for efficient use of fuel. This strategy allowed swifts to reach average migration speeds well above 300 km/day in spring, which is higher than possible for similar sized passerines. This study demonstrates that new technology may drastically change our views about migration routes and strategies in small birds, as well as showing the unexpected use of very limited geographical areas during migration that may have important consequences for conservation strategies for migrants.     

Comparative migration strategies of wild and captive‐bred Asian Houbara Chlamydotis macqueenii

For migratory species, the success of population reintroduction or reinforcement through captive‐bred released individuals depends on survivors undertaking appropriate migrations. We assess whether captive‐bred Asian Houbara Chlamydotis macqueenii from a breeding programme established with locally sourced individuals and released into suitable habitat during spring or summer undertake similar migrations to those of wild birds. Using satellite telemetry, we compare the migrations of 29 captive‐bred juveniles, 10 wild juveniles and 39 wild adults (including three birds first tracked as juveniles), examining migratory propensity (proportion migrating), timing, direction, stopover duration and frequency, efficiency (route deviation), and wintering and breeding season locations. Captive‐bred birds initiated autumn migration an average of 20.6 (±4.6 se) days later and wintered 470.8 km (±76.4) closer to the breeding grounds, mainly in Turkmenistan, northern Iran and Afghanistan, than wild birds, which migrated 1217.8 km (±76.4), predominantly wintering in southern Iran and Pakistan (juveniles and adults were similar). Wintering locations of four surviving captive‐bred birds were similar in subsequent years (median distance to first wintering site = 70.8 km, range 6.56–221.6 km), suggesting that individual captive‐bred birds (but not necessarily their progeny) remain faithful to their first wintering latitude. The migratory performance of captive‐bred birds was otherwise similar to that of wild juveniles. Although the long‐term fitness consequences for captive‐bred birds establishing wintering sites at the northern edge of those occupied by wild birds remain to be quantified, it is clear that the pattern of wild migrations established by long‐term selection is not replicated. If the shorter migration distance of young captive‐bred birds has a physiological rather than a genetic basis, then their progeny may still exhibit wild‐type migration. However, as there is a considerable genetic component to migration, captive breeding management must respect migratory population structure as well as natal and release‐site fidelity.     

African Odyssey project – satellite tracking of black storks Ciconia nigra breeding at a migratory divide

The African Odyssey project focuses on studying the migration of the black stork Ciconia nigra breeding at a migratory divide. In 1995–2001, a total of 18 black storks breeding in the Czech Republic were equipped with satellite (PTT) and VHF transmitters. Of them, 11 birds were tracked during at least one migration season and three birds were tracked repeatedly. The birds migrated either across western or eastern Europe to spend the winter in tropical west or east Africa, respectively. One of the juveniles made an intermediate route through Italy where it was shot during the first autumn migration. The mean distance of autumn migration was 6,227 km. The eastern route was significantly longer than the western one (7,000 km and 5,667 km respectively). Important stopover sites were discovered in Africa and Israel. Wintering areas were found from Mauritania and Sierra Leone in the west to Ethiopia and Central African Republic in the east and south. One of the storks migrating by the eastern migration route surprisingly reached western Africa. Birds that arrived early in the wintering areas stayed longer than those arriving later. On the average, birds migrating via the western route spent 37 d on migration compared to 80 d for birds migrating via the eastern route. The mean migration speed in the autumn was 126 km/d and the fastest stork flew 488 km/d when crossing the Sahara. The repeatedly tracked storks showed high winter site fidelity.     

OFFICIAL ANNOUNCEMENTS

The Lesser Crested Tern Thalasseus bengalensis emigratus breeding population in the Mediterranean is found exclusively in Libya, on the two coastal islands of Gara and Elba and one wetland on the mainland coast at Benghazi. In order to improve knowledge of the species migration to wintering quarters in West Africa, a ringing programme was conducted from 2006–2008 and 2009–2012. From a total of 1 354 nestlings ringed using metal and/or colour rings, 64 were recovered along their flyway and in their wintering range, representing 6.9% of birds ringed with both colour and metal rings. This provided the opportunity to collect information on post-natal movements (staging and wintering ranges), breeding philopatry and recruitment, in addition to a preliminary estimate of their migration journey duration. This paper indicates sighting and recovery distributions in space and time, highlighting the important areas for the species during its journey between breeding and wintering sites. The findings indicate that several areas where ringed terns stop-over during pre- and post-breeding migration journeys are not protected, causing an additional threat to their survival, as some wintering areas are also not protected. Conservation of this highly localised and threatened population needs not only to address protection at breeding sites but also at migratory stop-overs and wintering strongholds.     

Differential mortality of wintering shorebirds on the Banc d'Arguin, Mauritania, due to predation by large falcons

Predators may influence many aspects of the daily life and seasonal movements of their prey. Here we quantify direct, and evaluate indirect effects of predation by three falcon species (Lanner Falcon Falco biarmicus , Barbary Falcon Falco pelegrinoides and Peregrine Falcon Falco peregrinus ) on coastal shorebirds wintering on the Banc d'Arguin, Mauritania, an area hosting approximately 30% of the East Atlantic Flyway population of shorebirds. On the basis of 754 h of observation over five winters, 97 witnessed attacks and 585 collected prey remains, we show that shorebirds were safer in larger flocks, which tended to be attacked less often. Furthermore, species that forage relatively close to shore and in small flocks were depredated more often than expected from their relative abundance. In three species, Red Knot Calidris canutus canutus , Bar-tailed Godwit Limosa lapponica taymyrensis and Dunlin Calidris alpina , the juveniles were more vulnerable than adults. We estimated that on average 1% of the juvenile and 0.1% of the adult Red Knots present were killed by large falcons each winter. For Red Knots we simultaneously quantified annual survival on the basis of an individual colour-marking programme: mortality due to predation by falcons accounted for an estimated 6.2% (juveniles) and 0.8% (adults) of annual mortality. We suggest that juvenile Red Knots are 10 times as likely to be killed by falcons because they use riskier habitats, i.e. early and late tide foraging areas closer to shores where surprise attacks are both more common and more successful. These results indicate that the strength of indirect effects of predation operating in a shorebird population largely outweigh the effects of mortality per se .     

Climatic conditions during outward migration affect apparent survival of an arctic top predator,the peregrine falcon Falco peregrinus

In long‐lived species, population growth rate is highly sensitive to changes in adult survival. Despite the growing concerns regarding recent climate changes, few studies have investigated the effect of climatic conditions on survival in long‐lived wildlife that are either resident or breed in the Arctic. In this study, we evaluated the effect of climate across the annual life cycle (breeding, outward migration, wintering, and inward migration) on apparent annual survival of arctic‐breeding peregrine falcons. From 1982 to 2008, peregrine falcons breeding near Rankin Inlet, Nunavut, Canada were monitored, in part, to assess apparent annual survival (the product of true survival and site fidelity) using re‐observations of marked individuals. Our study indicated that apparent annual survival of adult peregrine falcons was correlated with indices of climatic conditions during outward migration (i.e., flight from the Arctic breeding grounds). These climatic indices (fall NAO of the current year and fall NAO with a lag of one year) explained 35% of the temporal variation in apparent annual survival of peregrine falcons. Our results suggest that this top‐predator is vulnerable to weather‐related environmental conditions encountered during fall migration.     

Investigating connectivity and seasonal differences in wind assistance in the migration of Common Sandpipers

Many migratory bird species have undergone recent population declines, but there is considerable variation in trends between species and between populations employing different migratory routes. Understanding species-specific migratory behaviours is therefore of critical importance for their conservation. The Common Sandpiper Actitis hypoleucos is an Afro-Palaearctic migratory bird species whose European populations are in decline. We fitted geolocators to individuals breeding in England or wintering in Senegal to determine their migration routes and breeding or non-breeding locations. We used these geolocator data in combination with previously published data from Scottish breeding birds to determine the distributions and migratory connectivity of breeding (English and Scottish) and wintering (Senegalese) populations of the Common Sandpiper, and used simulated random migrations to investigate wind assistance during autumn and spring migration. We revealed that the Common Sandpipers tagged in England spent the winter in West Africa, and that at least some birds wintering in Senegal bred in Scandinavia; this provides insights into the links between European breeding populations and their wintering grounds. Furthermore, birds tagged in England, Scotland and Senegal overlapped considerably in their migration routes and wintering locations, meaning that local breeding populations could be buffered against habitat change, but susceptible to large-scale environmental changes. These findings also suggest that contrasting population trends in England and Scotland are unlikely to be the result of population-specific migration routes and wintering regions. Finally, we found that birds used wind to facilitate their migration in autumn, but less so in spring, when the wind costs associated with their migrations were higher than expected at random. This was despite the wind costs of simulated migrations being significantly lower in spring than in autumn. Indeed, theory suggests that individuals are under greater time pressures in spring than in autumn because of the time constraints associated with reproduction.     

Broad wintering range and intercontinental migratory divide within a core population of the near‐threatened pallid harrier

Aim To identify the migration routes and wintering grounds of the core populations of the near‐threatened pallid harrier, Circus macrourus, and highlight conservation needs associated with these phases of the annual cycle. Location Breeding area: north‐central Kazakhstan; Wintering areas: Sahel belt (Burkina Faso to Ethiopia) and north‐west India. Methods We used ring recovery data from Kazakhstan and satellite tracking data from 2007 to 2008 on six adults breeding in north‐central Kazakhstan to determine migration routes and locate wintering areas. In addition, one first‐year male was tagged in winter 2007–2008 in India. Results Data evidenced an intercontinental migratory divide within the core pallid harrier population, with birds wintering in either Africa or India. The six individuals tagged in north‐central Kazakhstan followed a similar route (west of the Caspian Sea and Middle East) towards east Africa, before spreading along the Sahel belt to winter either in Sudan, Ethiopia, Niger or Burkina Faso. Spring migration followed a shorter, more direct route, with marked interindividual variation. The bird tagged in India spent the summer in central Kazakhstan. Half of the signal losses (either because of failure or bird mortality) occurred on the wintering areas and during migration. Main conclusions Our study shows that birds from one breeding area may winter over a strikingly broad range within and across continents. The intercontinental migratory divide of pallid harriers suggests the coexistence of distinct migratory strategies within the core breeding population, a characteristic most likely shared by a number of threatened species in central Asia. Conservation strategies for species like the pallid harrier, therefore, require considering very large spatial scales with possibly area‐specific conservation issues. We highlight urgent research priorities to effectively inform the conservation of these species.     

THE BEHAVIOUR OF THE HOTTENTOT TEAL

Following recovery and successful rehabilitation, a young Steppe Eagle Aquila nipalensis was tagged with a 45 g GPS satellite transmitter to track its migration and identify potential wintering and summering areas of the species passing through the United Arab Emirates (UAE). The study is part of a larger study on understanding migration of important birds of prey species from the UAE. The satellite-tagged Steppe Eagle was released near the town of Al Ain, UAE on 5 January 2009 and was tracked until 6 November 2010. Two complete spring and autumn migrations were tracked in addition to its onward autumn migration from the UAE. The tagged eagle continued its autumn migration from its release site and reached Yemen after stopovers in Saudi Arabia. Unlike other Steppe Eagles, the bird did not cross the strait of Bab-al-Mandeb and wintered in the area before undertaking its first spring migration. In the second spring migration in 2010, the bird migrated along the Suez–Eilat route and demonstrated a loop migration. The bird spent the summer on the steppes in Kazakhstan, with marked differences in the home ranges between 2009 and 2010, whereas wintering areas used in 2009 and 2010 in Tanzania were overlapping.     

Migration, wintering and breeding of a lesser spotted eagle ( Aquila pomarina) from Slovakia tracked by satellite

In northern Slovakia an adult male Lesser Spotted Eagle (Aquila pomarina) occupied the same nest site for 11 years running (1992–2002), where it was ringed and fitted with two satellite transmitters. In six of these years it successfully reared a young. In 1994 and 2000–2002 its behaviour during migration could be followed in detail by means of satellite telemetry. The eagle took the known route for this species to South Africa. In 2001, it spent 43% of the year at its breeding site, 33% in its winter quarters, the remaining 24% being spent on migration. In three cases the autumn migration took 40, 48 and 61 days respectively. In two cases the spring migration took 49 days. All five recorded autumn and spring migrations averaged a daily flight distance of 178 km. In spring the daily flight distance was in general slightly greater than in autumn. The longest was recorded from 30 March to 2 April 2001, between Uganda and the Red Sea, during which the bird covered a total of 1,650 km, averaging 412 km per day. In 2001, the spring migration from the wintering grounds was 2 weeks later than in 2002. The wintering grounds, where in 2 years the bird spent around 3.5 months, covering at least 1,666 and 2,269 km, respectively, comprised a large part of Zimbabwe together with the Kruger National Park in South Africa and neighbouring parts of Mozambique. The annual journeys flown, including movements around the wintering grounds, amounted in 2000-2001 to at least 20,396 km and in 2001-2002 to 19,041 km. Except during its crossing of the Sahara, the eagle must have taken food on nearly all its days of migration.