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Habitat conditions surrounding individual birds are key components determining their fitness, notably by influencing effective foraging, escape from predators, and adaptation to changing environmental conditions. Birds living in dynamic habitats are particularly likely to have a high need to explore; however, spatial and temporal patterns of exploratory movements are poorly understood. We investigated the exploratory movements of adult common shelducks (hereafter Shelducks, Tadorna tadorna) in the Wadden Sea, which provides a dynamic habitat for birds. We captured nine shelducks in adjacent breeding areas and attached GPS satellite telemetry devices for 5–18 months, mostly covering the post-breeding period. We analyzed bird-movement patterns based on mean daily locations and behavioral change point analysis. All individuals explored on a median of 22% of tracking days (range = 6–39%). Individuals usually explored new areas for a short time before switching to stay in these areas for longer periods. Exploratory movements were particularly frequent before the start of the flightless period during molting. During this time, shelducks explored the traditional molting area in the Elbe estuary intensively. However, birds did not explore places within the area subsequently used for molting for longer or more often than other places. The molting area was used for a median of 59 days, i.e., about twice as long as required for the flightless period, suggesting that this area was explored not only to select a suitable molting place, but also for other purposes. Only two shelducks performed longer-distance exploration movements, i.e., > 45 km from their sedentary areas. We therefore concluded that exploratory movements by adult shelducks may enable the birds to adapt to small-scale changes in habitat conditions. [ABSTRACT FROM AUTHOR]

The migratory behaviour of Ospreys (Pandion haliaetus) has been well studied using satellite telemetry, but studies on their behaviour in the breeding area are scarce. We caught and fitted 17 adult Ospreys with solar-powered GPS-enhanced satellite transmitters in northeast Germany and tracked them for up to 7 years. There was a high variation in home range size depending on sex, nesting site and breeding success. The home ranges of successfully breeding males (median 33.4 km2, 95% kernel density estimations) were significantly larger than those of females (median 4.6 km2) and varied in extent and shape between individuals. Some females made long excursions and sometimes spent the night at great distances to their nests after the juveniles had fledged but they also returned to the nesting area before they left for migration. The males' home range areas were consistent during the breeding period. The proportion of water surfaces on the home range areas of males ranged between 9.6 and 29%. The overnight roosts were found in distances up to 7.83 km (median 980 m) for successfully breeding males and up to 105 km (median 568 m) for successfully breeding females. The correlation between overnight roost-nest distance and the corresponding home range area was significant for females but not for males. The overlap in the home ranges of individual males that occupied the same nests in different years varied between 37.3 and 54.7% of the mutual home ranges. Males partly included the same waterbodies in their home ranges, but they also visited different lakes. In the incubation and nestling phases, females are closely bound to the nest, whereas their mates can range over vast areas. [ABSTRACT FROM AUTHOR]

The breeding behaviour of raptors is determined by many characteristics, such as courtship and mating patterns, nest building, foraging, territorial defence activities, clutch incubation, and caring for the young. Here, we study the breeding behaviour of the Red Kite (Milvus milvus), a European native bird of prey. From a period between 2018 and 2022, we analysed data for 33 adult Red Kites (14 males and 19 females) during 70 successful breeding episodes in Austria, the Czech Republic, and Slovakia. Using satellite telemetry and in situ observations, we found differences between males and females in the size of the home range, number of nights on the nest, and maximum distances from the nest. We analysed the influence of different factors on movement activity, breeding productivity, and home range size. Females spent significantly more nights on the nest than did males, flew shorter distances from the eyrie, and occupied smaller areas. Red Kites with two or more breeding experiences arrived significantly earlier than did unexperienced Kites in their first breeding attempts. Juveniles departed from the nest sooner than did their parents. Birds with more fledged juveniles occupied smaller home ranges. Our study reveals new knowledge of substantially different breeding behaviours in male and female Central European Red Kites. [ABSTRACT FROM AUTHOR]

We undertook field surveys of the critically endangered Bengal Florican throughout its range in India and Nepal and used the results to develop models of distribution to identify new populations. We also tagged 11 birds with satellite transmitters to assess their distribution and habitat use during the non-breeding season, about which nothing is known. The models suggest that the distribution is now extremely fragmented in the west, although potentially sizeable populations may await discovery in eastern parts of the species’ range, particularly along the Brahmaputra River. After breeding, tagged birds left their breeding sites inside protected areas (PAs) and moved up to 80 km into landscapes characterised by relatively low-intensity agriculture along rivers with lower than average human population densities. Many birds spent more than six months away from their breeding grounds outside PAs. Models of non-breeding distribution suggest that some breeding areas become unsuitable at that time of the year, and therefore that birds may be forced to leave PAs at that time. Tagged birds had high annual adult survival rates (0.92, 95% confidence interval 0.858-0.953). Home ranges during the non-breeding season were significantly larger than breeding season home ranges. The results suggest that the conservation of this species needs to account for the species’ use outside the breeding season of less intensively cultivated floodplain-agricultural landscapes, as well as protecting breeding grassland sites. [ABSTRACT FROM AUTHOR]

Fast-moving technological advances, such as satellite tracking technologies, are providing in-depth information of aspects of avian ecology hitherto unknown. In fact, detailed information about movement ecology and ranging behaviour of birds is important not only from the perspective of the basic ecology, but also from the conservation point of view. This is particularly important in European countries where agricultural intensification, land abandonment and the withdrawal of traditional management agro-forestry practices pose a threat to biodiversity. The Booted Eagle, likewise other forest raptors, is an adequate bioindicator of human-dominated agro-forestry Mediterranean landscapes in which low-intensity traditional agricultural practices still persist. Here, using a combination of an unbiased technology (i.e., GPS telemetry), a wide geographic extension of marked birds (all over Spain), and much larger sample size than in previous works, we provide the first quantitative assessment of the home range size and space use of the Booted Eagle by means of GPS satellite telemetry during the breeding season. Interestingly, our results revealed different levels of space use over the breeding season and showed that eagles perform long distance foraging movements (i.e., >20 km) from the nest throughout the breeding season. This resulted in larger home ranges than reported thus far, and, more interestingly, in an extremely eccentric topology of territories. Hence, management measures for conservation of forest raptors based on setting restrictions around nesting sites using buffer areas of arbitrary radii clearly results in large areas of eagles' home ranges laying outside 'restriction' areas. Therefore, conservation measures should take into account the full range of agro-forestry habitats encompassed within the home range. Finally, our results support the claim that a large-scale management approach beyond the establishment of a closed network of protected areas such as the Natura 2000 network is necessary for the conservation of Mediterranean raptors. [ABSTRACT FROM AUTHOR]

Knowledge of species' habitat requirements can be gained from studying individual variation in home range size, under the assumption that larger home ranges reflect increased resource needs or decreased habitat quality. We used satellite telemetry to delineate home ranges of South Scandinavian Common Cuckoos ( Cuculus canorus) throughout their annual cycle. Annual stage (breeding or non-breeding period) and percentage of forest cover were good predictors of home range size. Average breeding season home ranges were ten times as large as those of non-breeding home ranges, suggesting strong temporal variation in the birds' resource needs, and perhaps lower habitat quality in the breeding range compared to the African part of their annual range. Furthermore, although the Cuckoos rarely chose a home range with complete forest cover, we found a significant negative relationship between forest cover and home range area. This suggests that heterogeneous landscapes which include some dense forest cover constitute important habitat for Cuckoos, and that the continuing trend of forest loss in tropical Africa could reduce habitat quality for the Cuckoo in the non-breeding season. [ABSTRACT FROM AUTHOR]

We compared migration movements and chronology between Northern Pintails ( Anas acuta) marked with dorsally mounted satellite transmitters and pintails marked only with tarsus rings. During weekly intervals of spring and autumn migration between their wintering area in Japan and nesting areas in Russia, the mean distance that ringed pintails had migrated was up to 1000 km farther than the mean distance radiomarked pintails migrated. Radiomarked pintails were detected at spring migration sites on average 9.9 days (90 % CI 8.0, 11.8) later than ringed pintails that were recovered within 50 km. Although ringed and radiomarked pintails departed from Japan on similar dates, the disparity in detection of radiomarked versus ringed pintails at shared sites increased 7.7 days (90 % CI 5.2, 10.2) for each 1000 km increase in distance from Japan. Thus, pintails marked with satellite transmitters arrived at nesting areas that were 2500 km from Japan on average 19 days later than ringed birds. Radiomarked pintails were detected at autumn migration stopovers on average 13.1 days (90 % CI 9.8, 16.4) later than ringed birds that were recovered within 50 km. We hypothesize that dorsal attachment of 12-20 g satellite transmitters to Northern Pintails increased the energetic cost of flight, which resulted in more rapid depletion of energetic reserves and shortened the distance pintails could fly without refueling. Radiomarked pintails may have used more stopovers or spent longer periods at stopovers. causing their migration schedule to diverge from ringed pintails. We urge further evaluation of the effects of dorsally mounted transmitters on migration chronology of waterfowl. [ABSTRACT FROM AUTHOR]

Satellite telemetry has become a common technique to investigate avian life-histories, but whether such tagging will affect fitness is a critical unknown. In this study, we evaluate multi-year effects of implanted transmitters on migratory timing and reproductive performance in shorebirds. Shorebirds increasingly are recognized as good models in ecology and evolution. That many of them are of conservation concern adds to the research responsibilities. In May 2009, we captured 56 female Black-tailed Godwits Limosa limosa limosa during late incubation in The Netherlands. Of these, 15 birds were equipped with 26-g satellite transmitters with a percutaneous antenna (7.8 % ± 0.2 SD of body mass), surgically implanted in the coelom. We compared immediate nest survival, timing of migration, subsequent nest site fidelity and reproductive behaviour including egg laying with those of the remaining birds, a comparison group of 41 females. We found no effects on immediate nest survival. Fledging success and subsequent southward and northward migration patterns of the implanted birds conformed to the expectations, and arrival time on the breeding grounds in 2010-2012 did not differ from the comparison group. Compared with the comparison group, in the year after implantation, implanted birds were equally faithful to the nest site and showed equal territorial behaviour, but a paucity of behaviours indicating nests or clutches. In the 3 years after implantation, the yearly apparent survival of implanted birds was 16 % points lower. Despite intense searching, we found only three eggs of two implanted birds; all were deformed. A similarly deformed egg was reported in a similarly implanted Whimbrel Numenius phaeopus returning to breed in central Alaska. The presence in the body cavity of an object slightly smaller than a normal egg may thus lead to egg malformation and, likely, reduced egg viability. That the use of implanted satellite transmitters in these large shorebirds reduced nesting propensity and might also lead to fertility losses argues against the use of implanted transmitters for studies on breeding biology, and for a careful evaluation of the methodology in studies of migration. [ABSTRACT FROM AUTHOR]

Location data of four White-tailed Sea Eagles ( Haliaeetus albicilla) (WTSE) from four pairs equipped with GPS data loggers or automated GPS-GSM units and visual behaviour observations were used to record their home range size and territoriality. Between 18 and 571 positions were received from the satellite devices. Extensive excursions were identified by defining the distance to the activity centre and have been removed before home ranges were computed. Home range size varied considerably among the individuals tracked. Minimum convex polygons, with outliers removed, ranged between 2.25 and 19.16 km and 95 % kernel contours (calculated in Ranges 8) varied from 2.37 to 12.04 km in the Mecklenburg Lake District. Occurrence of territorial behaviour as identified by visual observations changed significantly throughout the year with a maximum in May and a minimum in December. An optimal habitat quality characterized by shallow and fish-rich freshwater lakes with undisturbed nesting areas in surrounding forests is a prerequisite for small home ranges and for the high abundance of breeding birds found within the Mecklenburg Lake district. The year-round territoriality is attributed to a sufficient food supply throughout the seasons, either by mild winters allowing access to fish and/or waterfowl on open waters or, in hard winters, to the availability of carcasses and remains of larger animals from hunting activities when frozen lakes restricte access to prey. [ABSTRACT FROM AUTHOR]

Eleonora's Falcon ( Falco eleonorae) is an endemic breeder of the Mediterranean Sea and the Canary Islands that overwinters in Madagascar and surrounding areas. Recent telemetry studies have revealed the migratory journey of falcons from the western and central Mediterranean breeding colonies. Our study complements the puzzle of the species' migration providing data from an eastern Mediterranean breeding colony. In this paper, we describe for the first time the migratory routes of four falcons originating from the Aegean Sea, the core of the species' breeding range. We tracked two adults and two immature siblings to their wintering grounds in Madagascar. According to our results, the timing of migration was consistent with previous studies. Our findings also suggest that the falcons adjust their flight speed according to the environmental conditions encountered en route, by accelerating during open-sea and desert crossings and by slowing down in potential foraging areas. Moreover, the selection of common staging areas, both among the two siblings and among the two adults, highlights the role of these areas in the migratory cycle of the species. Finally, according to the home-range analysis on the wintering grounds, space use was rather variable across the four tracked falcons. Still, the falcons were more frequently observed within the submontane forest, one of the last patches of primary rainforest in Madagascar. Thus, future studies aiming at unveiling the ecological requirements of the species in its wintering quarters are considered as top priority. [ABSTRACT FROM AUTHOR]

The Kyrgyz population of the bar-headed goose Anser indicus has declined dramatically during the past decades. Human persecution during migration and habitat loss at stopover and wintering sites are commonly regarded as most serious threats. However, little is known about seasonal movements, migration routes, and wintering sites of the bar-headed geese from Kyrgyzstan, which represent the westernmost geographical population of the species. As part of a conservation project, which also included reinforcement of the wild population by the release of hand-reared juveniles, in late summer of 1998, five bar-headed geese, three wild adults and two hand-reared goslings, were fitted with sun-powered satellite transmitters in order to track their movements from Lake Son Kul and Lake Chatyr Kul in Kyrgyzstan. The five individuals contributed very unevenly to the more than 5,000 signals in total that were received from the French ARGOS system: one failed after 8 weeks, while another one was tracked for more than 2 years. The four geese contributing to this study followed three completely different migration routes leading to their wintering areas in Pakistan, India and Uzbekistan, while stopover areas were situated in southern Tajikistan and in western Tibet. Both in autumn and spring the adult birds migrated distances of 1,280–1,550 km in two steps, with stopover periods of 32–46 days (autumn) and 16–23 days (spring). Flight speeds of up to 680 km per actual migration day were recorded regularly, even during crossings of very high summits. A hand-reared juvenile flew non-stop for 790 km to southern Uzbekistan and even visited southernmost Turkmenistan, where the species is very rarely seen. The timing of migration varied considerably between individuals but also for the same individual between years. We compare our tracking results with previous findings (field observations, ring recoveries, and satellite tracking results) and discuss them with respect to migration over high-mountain habitats and a general migration strategy of the species. [ABSTRACT FROM AUTHOR]

New technologies enable tracking of the route, duration, and destination of previously unassessed long-distance movements. Fledgling Australasian Gannets Morus serrator from breeding populations in New Zealand had been reported to fly across the Tasman Sea to Australia, with this historic knowledge derived from the recovery of banded carcasses and from observations of initial flight direction. We deployed Argos satellite devices on ten M. serrator fledglings at Cape Kidnappers Gannetry, North Island, New Zealand, across 2 years. Birds that were tracked leaving the colony initially appeared to have landed on the sea. A male bird and two female birds were tracked moving along the east coast to the south tip of New Zealand. The two females then crossed the Tasman Sea to eastern Australian coastal waters in 4 and 5 days, respectively. We suggest that, contrary to historic reports, the route via Stewart Island constitutes a realized migration path for fledglings from Cape Kidnappers, which might minimize the distance traveled across the open sea to southeastern Australia or Tasmania. Our results further imply that initial direction of flight needs not be indicative of the subsequent migration route taken by M. serrator. This highlights the importance of direct tracking technology for adequate assessment of dispersal and migration in seabirds and other highly mobile species. [ABSTRACT FROM AUTHOR]

Although juvenile dispersal is an important life history component, it remains one of the less understood ecological processes regulating the dynamics of animal populations. Lack of information about patterns of dispersal hampers the estimation of the actual status and demographic trajectory of populations, and can preclude the development of sound conservation strategies. The Eagle Owl Bubo bubo is an endangered bird species in the European Alps. Many breeding sites have been abandoned in the twentieth century, although some recovery has been reported lately. Moreover, the occupancy of traditional breeding sites across years in well-monitored Alpine populations varies a lot, this despite a relatively high breeding success at the population level. This raises concern about the long-term persistence of Alpine populations. Using conventional and satellite radiotracking, we investigated the spatio-temporal dispersal of 41 juvenile Eagle Owls originating from a population in the southwestern Swiss Alps. Our main goal was to determine dispersal distances, places and times of post-dispersal settlement. Juveniles left their parents between mid-August and mid-November. They covered, on average, 12.7 km per night (linear distance between two consecutive day roosts), often crossing high mountain ranges (up to 3,000 m altitude). The mean total distance covered by an individual during dispersal was 102 km (sum of night movements), with a maximum of 230 km. Settlement places were, on average, 46 km distant from the birth place. Our study establishes long-distance dispersal in juvenile Eagle Owls, even in a complex topography, suggesting the existence of a wide-scale metapopulation system across the northwestern Alps. This metapopulation dimension should be accounted for in conservation plans. [ABSTRACT FROM AUTHOR]

We tracked the daily movements of three juvenile golden eagles (Aquila chrysaetos) using satellite telemetry. Straight distances covered in an hour and throughout a day were calculated. Daily movements of golden eagles are mostly characterized by short-distance excursions, with 64% of the distances covered in an hour shorter than 1 km and 95% shorter than 9 km. Both the longest movements and the largest proportion of long-distance movements, were concentrated between 1100 and 1800 hours, the peak of daily activities. Average hourly distances during that peak oscillated between 2 and 6 km, with records of more than 20 km. Distances covered in a day ranged between 0.1 and 53.2 km with an average of 14.0 km (SD=13.4). Differences in the distances covered at different times of the day probably reflect a balance between the temporal pattern of preferred prey’s activity and the eagles’ progressive satiation along the day on one hand, and the higher likelihood of thermal and updraughts (which facilitate long-distance movements) occurring at noon and the early afternoon, on the other. [ABSTRACT FROM AUTHOR]

By means of satellite telemetry, the migrations of three young Egyptian vultures ( Neophron percnopterus) from France and Bulgaria were studied and data obtained (over 4,300 Argos locations) to describe movement patterns, timing of migration, routes followed, speed of flight and ranging behaviour in Africa. Two French vultures migrated at almost the same time and, after travelling ca. 3,570 km, remained in the Sahelian zone, in southern Mauritania. The Bulgarian bird, after travelling 5,340 km, ended in south-east Chad, in the Sudano-Sahelian zone. It was possible to determine two remarkably long daily flight distances of this bird of over 500 km on two successive days (1,017 km in total) when crossing the Sahara. In January and February, the Bulgarian bird wandered extensively over 2,600 km, even as far as north-east Nigeria. Both French vultures remained in their home ranges in Mauritania once they had adopted them, which extended to 69,000 km2 and 50,000 km2, respectively. One continuously-tracked vulture from France first left its African home range when 3 years old (probably in its fourth plumage type). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]