Honey Buzzard Pernis Apivorus Research Articles

Sex differences in the timing of spring migration of adult European Honey Buzzards Pernis apivorus in the Central Mediterranean

Sex differences in the timing of spring migration of adult European Honey Buzzards Pernis apivorus in the Central Mediterranean

Assessment of the consumption of the exotic Asian Hornet Vespa velutina by the European Honey Buzzard Pernis apivorus in southwestern Europe

ABSTRACT Capsule The Asian Hornet Vespa velutina was the second most important species in the diet of the European Honey Buzzard Pernis apivorus in southwestern Europe, just four years after the appearance of the exotic wasp in the study area. Aims To assess the consumption of the invasive Asian Hornet by the European Honey Buzzard in southwestern Europe, following the Asian Hornet’s appearance there in 2014. Methods In northwestern Spain, we installed trail cameras in, and collected wasp comb remains from, nine nests of European Honey Buzzards (five in 2018 and four in 2019). We estimated the representation of the Asian Hornet in the birds’ diet, as well as the number of colonies attacked. We also compared the nesting frequency and density of breeding pairs before (2004–13) and after (2014–20) the Asian Hornet’s appearance. Results We detected consumption of the Asian Hornet at all the nests we examined. The Asian Hornet was the second most abundant wasp species in the diet and it was the most abundant in 2018 based on biomass. During the breeding season, each pair of European Honey Buzzards attacked 34–61 colonies in 2018 and 15–28 in 2019. Nesting frequency rose from 60% before the Hornet’s appearance to 100% afterward, while the density of breeding pairs increased by 300%. Conclusion Our results suggest that the Asian Hornet is becoming an important part of the diet of the European Honey Buzzard. This finding opens a research avenue to assess the potential role of the raptor in the management of the invasive social wasp.

Rattling Call of Crested Honey Buzzard Pernis ptilorhynchus

We describe, for the first time, the rattling call of the Crested Honey Buzzard Pernis ptilorhynchus. This was previously considered to be a unique vocalization of European Honey Buzzard Pernis apivorus; however, we detected this series of rapidly repeated notes given by an adult female, a second-year, a juvenile and a nestling Crested Honey Buzzard. The rattling calls appeared to be given at times of great excitement, such as to an approaching intruder, mate or parent at the nest, or to a familiar person who usually gave food in the case of captive individuals. The rattling call of an adult female Crested Honey Buzzard at the nest was at a frequency of 2.12 (s.d.±0.07) kHz, and lasted 141 (s.d.±18) ms, which was higher and longer than in European Honey Buzzard.

Brood Sex Ratio in European Honey Buzzards Pernis apivorus is Related to Spring Phenology

In sexually size-dimorphic bird species, rearing costs of sons and daughters usually differ and may be important in the evolution of offspring sex ratio adjustment. Raptors have reversed sexual size dimorphism and the smaller males are sometimes found to be overrepresented in food-poor territories or years. As a raptor with small reversed sexual dimorphism (6% in body mass), the European Honey Buzzard Pernis apivorus is expected to show little or no brood sex ratio bias in relation to environmental conditions. We molecularly sexed 311 chicks of 195 broods in and around The Netherlands, during 1996–2014. We examined which environmental factors explained brood sex ratio variation best. Overall, sex ratio was not biased (all nests pooled: 50.8% females) but more females were produced in years when on average Honey Buzzards bred earlier (32% sex ratio change over a ten-day range in annual mean laying date). Within-year laying date variation, hatching order, abundance of wasp (Vespinae) nests (main food source) and summer weather did not explain sex ratio variation. In the Veluwe and Drenthe (1974–2014), Honey Buzzards laid eggs earlier when the spring was warmer, which resulted in a c. 9-day advance in laying date over 40 years. As warm spring weather was also a predictor of a higher density of wasp colonies, we expected female chicks to benefit more from growing up in wasp-rich years than males, if the sex ratio biases were adaptive. However, this differential growth benefit was not noticeable in chick body mass; chick body mass was best explained by negative effects of relative laying date (within a year) and hatching order. The potential benefit for female nestlings (compared to males) of growing up in years with warm springs, when egg laying occurs early and wasp colonies are more abundant, remains unknown.

Differential timing of autumn migration between sex groups in adult European honey buzzards Pernis apivorus

The European honey buzzard Pernis apivorus is a summer visitor in Europe, wintering mostly in West-central Africa. Previous studies concerning timing of autumn migration in relation to sex groups provided contrasting results. In particular, a field survey made in southern Sweden did not report differences in timing, while a satellite study via GPS tracking on six adults, three males, and three females, revealed that the latter departed earlier. The aim of this 4-year study is to further investigate the timing of autumn migration in this species carrying out observations at the Strait of Messina, a bottleneck located along the Central Mediterranean flyway, between August 10th and September 30th 2016–2019. Adult European honey buzzards concentrated the passage between late August early September, with females passing on average 5 days earlier than males. It is suggested that a different role of sexes concerning exhibition of territorial displays during the late breeding season, would explain differences between sex groups in timing of both moult and autumn migration.

Local and Regional Wind Patterns Affect Spring Migration Magnitude, Flyways and Flocking Of European Honey-Buzzards Pernis apivorus at the Strait of Messina

During spring migration, a few tens of thousands of European Honey-buzzards wintering in sub-Saharan Africa cross the central Mediterranean to reach their breeding grounds in central-eastern Europe. In so doing they concentrate passage through the Sicilian Channel but choose different flyways in response to different wind conditions. This study investigated the influence of local and regional wind conditions on the movement patterns of this species along the Strait of Messina, a migration bottleneck located between eastern Sicily and southern continental Italy where some raptors fall victim to illegal shooting by poachers each spring. Simultaneous observations occurred at four watchpoints, three on the Sicilian side and one on the continental boundary (Calabrian side). Although northwesterly winds prevailed at the Strait during peak migration days, slightly different local patterns of both horizontal and vertical winds at each observation site affected flocking and shaped the passage of raptors through this bottleneck, broadening the migration front. The results confirm that the magnitude of Honey-buzzard spring migration at the Strait is strongly affected by wind patterns in the Sicilian Channel. In particular, migrants concentrate at this bottleneck after crossing the Channel in northwesterly winds the previous day. In conclusion, by interpreting migratory behaviour both at local and regional scales, this work can help to plan more efficient monitoring of Honey-buzzards through the Strait and improving the siting of conservationist efforts. —Agostini, N., Chiatante, G., Gustin, M., Cento, M., von Hardenberg, J., Dell'Omo, G. & Panuccio, M. (2021). Local and regional wind patterns affect spring migration magnitude, flyways and flocking of European Honey-buzzards Pernis apivorus at the Strait of Messina. Ardeola, 68: 373-390.

Forest Availability and Fragmentation Drive Movement Behaviour of Wintering European Honey-Buzzard Pernis apivorus in Africa

Decreases in suitable habitat due to loss and fragmentation on the African non-breeding grounds are believed to be a driver of the declines in Palaearctic migrants. However, the effects of habitat loss and fragmentation on individual migrants have rarely been investigated. The European Honey-buzzard Pernis apivorus, a migratory forest specialist, displays the characteristics of a species that would be sensitive to declines in suitable habitat. We assessed site fidelity, habitat selection and home range characteristics of 32 tracked European Honey-buzzards in Africa to understand how habitat transformation on the non-breeding grounds affects the movement behaviour (particularly habitat use and home range characteristics) of the species. Adults had greater site fidelity than juveniles, indicating that young birds were exploring to locate suitable habitat for future non-breeding territories. Besides site fidelity, there were few significant differences between the movements of adult and juvenile Honey-buzzards. Birds of all age classes strongly selected treed habitat, as expected. Treed largest patch index and edge density had a negative effect on home range size, demonstrating that Honey-buzzards rely on large tracts of continuous forest, but can tolerate some level of fragmentation. Individuals with larger home ranges due to greater levels of forest fragmentation moved greater daily distances. In addition, Honey-buzzards spent more time in home ranges with larger treed largest patch indices and lower edge density. This reveals that birds that do not have access to a large patch of unfragmented forest are both flying greater distances on a daily basis and moving to new home ranges more often. This likely results in greater energy expenditure over their non-breeding period, which may have adverse effects on their long-term survival. Furthermore, our analyses support the hypothesis that continuing forest loss in Africa will have a negative effect on the European Honey-buzzard population.

Tree cover density attracts rare bird of prey specialist to nest in urban forest

Urban forests are important hotspots of biodiversity in the environment of cities and their surroundings but may also stand out from neighbouring forests by greater tree species diversity, higher tree age and greater share of deciduous species. However, they are usually not connected with nesting of rare birds of prey, especially dietary specialists. Unexpectedly, I have found Honey Buzzard Pernis apivorus nesting in such a forest in a 300,000-inhabitant city in North-Eastern Poland. The male of this pair was caught and fitted with a global positioning system logger. Using a tree cover density raster, I show that both for nesting and foraging, Honey Buzzards preferred dense canopies. Even with anthropogenic disturbance, the urban forest still offered the best conditions (greatest tree cover) for this specialist species in a 10 km radius. This finding shows that the advantages of some features of urban forests (deciduous character, dense canopy) can overcome disadvantages of the urban environment even for rare, large raptors. Also tree cover density seems a promising indicator of biodiversity in urban forests and should be tested in larger studies.

Highly skewed sex and age ratios of European Honey Buzzard in southern Africa

Sex and age segregation on the non-breeding grounds is common in raptor species. We studied the European Honey Buzzard (Pernis apivorus) on its southern African non-breeding grounds to examine changes in sex and age ratios over a period of recent population expansion (2002–2017). Photographs from multiple open sources were analysed. The adult population was found to be overwhelmingly female (93.3%) with no significant variation over months, years, or latitudes. This supports the arrival-time hypothesis, which states that the sex responsible for establishing the breeding territory (the male in honey buzzard) will spend the non-breeding period closest to the breeding grounds, allowing them to reduce intrasexual competition for breeding territories. Juvenile and second year birds (41.6% of the population) were more common at lower elevations, as well as further south in the sub-region. This is likely due to a funnelling effect of inexperienced juvenile birds further south and to coastal zones. In addition, juvenile birds do not return to the breeding grounds for at least 2 years, so may be more likely to migrate further south. Finally, second year birds increase later in the austral summer. This may be a result of both juvenile birds moulting into more adult plumage, and a southward intra-continental movement of young honey buzzards in Africa.

Exploitation of the invasive Asian Hornet Vespa velutina by the European Honey Buzzard Pernis apivorus

ABSTRACTThis paper reports the first case of predation on the nests of Asian Hornet Vespa velutina by the European Honey Buzzard Pernis apivorus, as well as the use of this resource by a breeding pair to provision their nestlings. The Asian Hornet is listed among the 100 most invasive alien species and is expanding in Western Europe. Our finding opens the door to a number of questions, including the effects of this additional allochthonous resource on the European Honey Buzzard populations, as well as the potential of this raptor as a biocontrol agent.

Diurnal birds of prey of national nature park ‘Dvorichanskyi’ and adjacent territories

The studies of species composition and abundance of diurnal birds of prey may be quite indicative of the state of natural ecosystems and of the level of impact of human-induced factors on their functions. Such studies are particularly important within the protected areas taking into account unfavourable conservation status of many species of the group. The status, abundance, aspects of habitat distribution and breeding habitat preferences of diurnal birds of prey were studied within national nature park ‘Dvorichanskyi’ and adjacent territories (750 sq. km, Dvorichanskyi district, Kharkiv Region, Ukraine) in 2010–2018. 22 species were registered. The breeding of six species was confirmed e.g. Black Kite (Milvus migrans), Marsh Harrier (Circus aeruginosus), Goshawk (Accipiter gentilis), Sparrowhawk (Accipiter nisus), Common Buzzard (Buteo buteo), Booted Eagle (Hieraaetus pennatus). The breeding of four more species is considered probable namely Honey Buzzard (Pernis apivorus), Montagu’s Harrier (Circus pygargus), White-tailed Eagle (Haliaeetus albicilla) and Hobby (Falco subbuteo). There are indications of possible breeding of Short-toed Eagle (Circaetus gallicus) and Kestrel (Falco tinnunculus). The rest of the species are migrating and/or wintering. The most numerous breeding species is Common Buzzard. The abundance of Booted Eagle is comparatively high that discerns the study area from other parts of Kharkiv Region. 40 nests of birds of prey were carefully inspected. The majority were found in ravine steppe forests (83%). Oak, alder and willow flood-plain forests are very important breeding habitats for Black Kite and Booted Eagle while ravine steppe forests are those for Goshawk, Sparrowhawk, Common Buzzard and Booted Eagle. Pedunculate oak (Quercus robur) is the most favourable tree species for building the nests (47.5% of all inspected nests) followed by European ash (Fraxinus excelsior) (15%) and European pear (Pyrus communis) (10%).

Flight Altitude of Migrating European Honey Buzzards Facing the Open Sea

Abstract Migrating birds adjust their behaviour in order to reach their final destination safely and in a timely manner. In doing so, they fly at different altitudes, but unlike passerines, raptors do not explore all air levels searching for the best tailwind assistance. Soaring species migrate over the mainland using updrafts to optimize soaring-gliding flight and reaching higher altitudes during midday. However, there is little information on which variables affect their flight altitude when facing the open sea, where thermals are very weak and they are forced to use powered flapping flight for a long time. To fill this gap, we recorded the flight altitude of migrating European Honey Buzzards Pernis apivorus as they crossed the Tyrrhenian Sea (Central Mediterranean) and passed over a small island. During four migratory seasons, we recorded the altitudes of birds when they reached the NE coast of Ustica, a volcanic island between Sicily and central Italy, and analysed data in relation to several variables. The results showed that the tendency to continue migrating, flock size, and wind speed are the most important features in explaining height variation in migrating European Honey Buzzards facing the open sea.

The Honey-Buzzards of the Sensebezirk: First Findings on Density, Diet, Reproduction and Food Competition in a Swiss Population of Honey-Buzzard Pernis Apivorus

In 2018 a nest of Honey-buzzard Pernis apivorus was found during a research project on Red kites Milvus milvus in Switzerland in an area where the cantons of Bern and Fribourg border. The diet was analysed by using a camera trap at the nest. In 2019 I started a private project to get an insight in Honey-buzzard density and reproduction in the area. 1)Territory density and reproduction: In 2018 one nest was found occasionally where two chicks fledged. In 2019, 8 territories were mapped in 54.3 hours of observing at high viewpoints, covering ca. 100 km2. At 7 territories the reproduction could be determined with a moderate certainty, resulting in only one successful territory where one young was raised. 2)Diet: By following nests with camera traps, diet was determined by number of prey items brought to the nest per adult. Two successful nests were followed, one in 2018 and one in 2019 during the chick rearing phase. Common wasp Vespula vulgaris and grey coloured combs, presumably dominated by European wasp Vespula germanica formed the most frequently delivered prey to both nests, but the share of the overall prey was bigger on the nest of 2018 than on the nest of 2019, resp. 68,9% and 60,1%. Also, the mean size of the combs per aforementioned wasp species was bigger in 2018 than in 2019. In 2019 more alternative prey were brought to the nest, like Hornet Vespa crabro, Bumblebee Apinae and one Vole Arvicolinae. 3)Wasp predation: Predation on social wasps was followed with camera traps at occasionally found wasp nests, three in 2018 and one in 2019. Honey-buzzards appeared in front of the camera at two of the three nests found in 2018, 5 individuals, but none started digging nor harvested from the nests. Badger Meles meles, Polecat Mustela putorius, Red fox Vulpus vulpus, and Pine marten Martes martes were recorded showing interest without predating on the nests. The single nest found in 2019 was predated completely by a Pine marten Martes martes.

Non-foraging tool use in European Honey-buzzards: An experimental test.

Examples of tool-use behaviors by birds outside foraging contexts are scarce and limited to a handful of species. We report a field experiment aimed to test whether an observed suite of odd behaviors by European Honey-buzzards (Pernis apivorus) represents use of green twigs cut from trees and woody shrubs as a tool to attract ants for anting. Specifically, we tested whether buzzards are selective in their choice of twigs, under the assumption that birds would prefer easy-to-collect twigs from plants that effectively attract ants. Experimental results lend support to our hypothesis that European Honey-buzzards cut green twigs of Montpellier maple trees (Acer monspessulanum) and, to a lesser extent, of Pyrenean oaks (Quercus pyrenaica) for their immediate use as ant attractors. Fresh twigs of both tree species attracted large numbers of ants, suggesting that their preferential use in the reported behavior of Honey-buzzards is not a random selection of the available plant material. Maple twigs, however, were the easiest to break and oak twigs the hardest compared to other plants in the community. This suggests that the relative ease of cracking of maple twigs may account for the preference Honey-buzzards have for this plant species as compared with Pyrenean oak, whose twigs demand considerable more effort from the birds to break. Our results lend support to the inclusion of the reported behavioral sequence by this raptor species as a potential example of tool use in birds outside the usual foraging context.

Autumn Passage of Soaring Birds over Dobrogea (Romania): A Migration Corridor in Southeast Europe

The Dobrogea region in southeastern Romania, which is part of the Eurasian-East African Flyway, is listed as one of the important migration corridors for soaring birds on the western coast of the Black Sea. However, our knowledge regarding migration intensity, phenology and geographical patterns of soaring birds over the area is poor. To determine the migration intensity and phenology of soaring birds, we recorded the autumn migration in the Măcin Mountains (northern Dobrogea) from mid-August to the end of October between 2002–2007. To describe the geographical patterns of migration at a regional scale, we recorded migration intensity in the second half of September in 2010 and 2011, simultaneously from 15 and 13 counting points, respectively, covering the entire region of Dobrogea. In the Măcin Mountains we recorded a mean number (±SD) of 11,297 ± 2333.5 (CV = 20.7%) migrating raptors per year, and of 21,367 ± 10,949.3 (51.2%) and 455.6 ± 43.6 (9.6%) migrating White Storks Ciconia ciconia and Black Storks Ciconia nigra, respectively. Migration phenology parameters varied across raptor and non-raptor species. Migration occurred over a broad front, covering all of Dobrogea. However, migration intensity was more pronounced in the western, central and eastern parts of the region, and was less intensive in the northern central areas. Overall, we recorded 30 migrating raptor species and three non-raptor species. The most abundant raptors were Common Buzzard Buteo buteo, European Honey Buzzard Pernis apivorus, Lesser Spotted Eagle Clanga pomarina, Eurasian Sparrowhawk Accipiter nisus and Western Marsh Harrier Circus aeruginosus. The three non-raptor species were White Stork, Black Stork and Great White Pelican Pelecanus onocrotalus. Our study provides the first general overview of the autumn passage of soaring birds over Dobrogea, highlighting the importance of this area as part of a global migration network.

Soaring across continents: decision‐making of a soaring migrant under changing atmospheric conditions along an entire flyway

Thermal soaring birds reduce flight‐energy costs by alternatingly gaining altitude in thermals and gliding across the earth's surface. To find out how soaring migrants adjust their flight behaviour to dynamic atmospheric conditions across entire migration routes, we combined optimal soaring migration theory with high‐resolution GPS tracking data of migrating honey buzzards Pernis apivorus and wind data from a global numerical atmospheric model.We compared measurements of gliding air speeds to predictions based on two distinct behavioural benchmarks for thermal soaring flight. The first being a time‐optimal strategy whereby birds alter their gliding air speeds as a function of climb rates to maximize cross‐country air speed over a full climb– glide cycle (Vopt). The second a risk‐averse energy‐efficient strategy at which birds alter their gliding air speed in response to tailwinds/headwinds to maximize the distance travelled in the intended direction during each glide phase (Vbgw).Honey buzzards were gliding on average 2.05 ms– 1 slower than Vopt and 3.42 ms– 1 faster than Vbgw while they increased air speeds with climb rates and reduced air speeds in tailwinds. They adopted flexible flight strategies gliding mostly near Vbgw under poor soaring conditions and closer to Vopt in good soaring conditions.Honey buzzards most adopted a time‐optimal strategy when crossing the Sahara, and at the onset of spring migration, where and when they met with the best soaring conditions. The buzzards nevertheless glided slower than Vopt during most of their journeys, probably taking time to navigate, orientate and locate suitable thermals, especially in areas with poor thermal convection.Linking novel tracking techniques with optimal migration models clarifies the way birds balance different tradeoffs during migration.

Seasonal detours by soaring migrants shaped by wind regimes along the East Atlantic Flyway.

Avian migrants often make substantial detours between their seasonal destinations. It is likely some species do this to make the most of predictable wind regimes along their respective flyways. We test this hypothesis by studying orientation behaviour of a long-distance soaring migrant in relation to prevailing winds along the East Atlantic Flyway. We tracked 62 migratory journeys of 12 adult European Honey Buzzards Pernis apivorus with GPS loggers. Hourly fixes were annotated with local wind vectors from a global atmospheric model to determine orientation behaviours with respect to the buzzards' seasonal goal destinations. This enabled us to determine hot spots where buzzards overdrifted and overcompensated for side winds. We then determined whether winds along the buzzards' detours differed from winds prevailing elsewhere in the flyway. Honey Buzzards cross western Africa using different routes in autumn and spring. In autumn, they overcompensated for westward winds to circumvent the Atlas Mountains on the eastern side and then overdrifted with south-westward winds while crossing the Sahara. In spring, however, they frequently overcompensated for eastward winds to initiate a westward detour at the start of their journey. They later overdrifted with side winds north-westward over the Sahel and north-eastward over the Sahara, avoiding adverse winds over the central Sahara. We conclude that Honey Buzzards make seasonal detours to utilize more supportive winds further en route and thereby expend less energy while crossing the desert. Lifelong tracking studies will be helpful to elucidate how honey buzzards and other migrants learn complex routes to exploit atmospheric circulation patterns from local to synoptic scales.

Wind Patterns affect Migration Flyways and Flock Size of a Soaring Bird over Sea

Water surfaces are natural barriers for raptors mostly using soaring–gliding flight over land during migration. Among these, the European Honey Buzzard ( Pernis apivorus) is a total migrant, breeding in Europe and wintering in central western Africa. Each spring thousands of buzzards undertake long sea crossings between Tunisia and southern Italy, concentrating over small islands en route to central eastern Europe. The aim of this research is to investigate the influence of wind patterns on the flyways used by these raptors during this critical phase of migration through field observations at four small Mediterranean islands (Pantelleria, Marettimo, Ustica and Panarea) and at the Straits of Messina between 20 April and 20 May 2006–2013. In our analyses, peak days were considered for each site. This eight year multisite study allowed the collection of a large data set. While crossing the Channel of Sicily, migrants concentrated over Pantelleria (southern side of the Channel) during moderate NW winds, and over Marettimo (northern side) during weaker southerly winds. Over the island of Ustica (north-western Sicily, Tyrrhenian Sea) raptors were observed mostly with weak southerly winds. Over the island of Panarea (northeastern Sicily) and at the Straits of Messina, European Honey Buzzards passed with weak winds from W and NW, respectively. The average flock size during the peak days was significantly higher over the island of Pantelleria, where birds migrated during the stronger winds. The results of this study show that wind patterns affect both migration pathways and flocking behaviour of this species while crossing large water surfaces.

Rare species of birds nesting in the area of the Rogów Forest District in the years 1949–2015

Abstract The aim of the study was to combine and summarize data on rare species of breeding forest birds found in the area of the Experimental Forest District near the Rogów village (Łódź Province). Our study area comprised 230 km2 of field and forest mosaic, where forests accounted for almost 17% of the area (13 forest complexes of 35-1000 ha). The results are based on the authors’ own field observations from the years 2000- 2015 as well as historical data since 1949 including original research papers, diploma theses, unpublished manuscripts, oral information and analyses of museum collections. The following criteria were used to categorise bird species as rare: (1) species that ceased breeding in the area, (2) taxa that were under strict protection and their abundance was no higher than 6 breeding pairs. In overall, 10 species were classified as rare, of which three do not breed in the area any more: grey heron Ardea cinerea, osprey Pandion haliaetus, European roller Coracias garrulus. However, non-breeding individuals of grey heron and osprey are still recorded in the area (the last cases of breeding pairs were recorded in the 1970s and 1961, respectively), while the European roller went extinct. In recent years, the abundance of another three species was probably stable: European honey buzzard Pernis apivorus, Eurasian hobby Falco subbuteo and nightjar Caprimulgus europaeus. Four species started breeding in the last 30 years: black stork Ciconia nigra, white-tailed eagle Haliaaetus albicilla, common crane Grus grus, stock dove Columba oenas. The trends in the abundance of the investigated species are similar to those observed in the country in overall.

Variable Shifts in the Autumn Migration Phenology of Soaring Birds in Southern Spain

While alteration of the migratory habits of birds is widely regarded as one of the most evident ecological effects of climate change, studies reporting shifts in migration phenology for long-lived, long-distance migrants have been few. Using time series of count data collected in southern Spain during autumn migration, we examined the magnitude and direction of phenological shifts for six common species of soaring birds. Many current methods for investigating phenological change rely on continuous data sets; however, these data may be unavailable for a variety of reasons. We used a cross-correlation analysis, which allowed us to compare recent data on the timing of migration from 1999–2011 to a historic data set collected during 1976–1977. The direction of phenological shifts for autumn migration was species-specific. White Storks Ciconia ciconia and Black Kites Milvus migrans appeared to have delayed passage, Black Storks Ciconia nigra and European Honey Buzzards Pernis apivorus have advanced their migra...