Comparison of the water-crossing behavior of Western Marsh Harriers(Circus aeruginosus) and European Honey Buzzards(Pernis apivorus) during autumn migration

We investigated the water-crossing behavior of Western Marsh Harriers(Circus aeruginosus),mostly adults,and European Honey Buzzards(Pernis apivorus),mostly juveniles,in relation to wind conditions,time of the day,flocking and age classes,at a watchsite in central Italy during the autumn migration en route to Africa.Although European Honey Buzzards are less suited than Western Marsh Harriers to undertake long sea crossings,they were more inclined to leave the coast when migrating in flocks.Few birds of both species chose to fly along the coast.Western Marsh Harriers,such as European Honey Buzzards migrating alone,undertook the water crossing rather than stopping migration(birds roosting at the site or flying back inland) during the absence of wind and vice versa during head winds.Conversely,European Honey Buzzards migrating in flocks were not affected in their decision(crossing or stopping migration) by wind direction.Both species undertook the water crossing rather than stopping migration during mornings and vice versa during afternoons.Finally,in both species,adults and juveniles showed the same behavior in front of a water barrier.This result was expected in the case of the Western Marsh Harrier but not from the European Honey Buzzard since,in this species,the water-crossing tendency is age dependent with adults avoiding sea crossings.Our study confirms that flocking significantly affects the water-crossing behavior of European Honey Buzzards during migration.Moreover,in this species,inexperience of juveniles and presumably younger adults,about the high energetic costs of long powered flight and about the existence of shorter routes over water,might explain the strong water-crossing tendency shown by migrants independently from their age.

Spring Has Sprung: the Buzzards Return

美国的鸟类中有双绝,一是加州燕子,二是俄亥俄州的秃鹰。它们都是春天的使者。前者会在每年的3月19日按时归来,后者则在3月15日归来。这已经有44年的历史了。3月15日这一天,数以百计的观众集结俄亥俄州的Cleveland,恭候秃鹰的归来,果然……读者朋友在欣赏完此短文后,勿忘品味一下本文的标题。】

Interspecific comparison of the flight performance between sparrowhawks and common buzzards migrating at the Falsterbo peninsula： A radar study

In order to compare the two species＇ flight performance over the exposed and windy Falsterbo Peninsula, where thermal conditions seldomly are very favorable, we used tracking radar to study flight parameters of sparrowhawks Accipiter ni- sus and common buzzards Buteo buteo during autumn migration. The results showed a clear difference between sparrowhawks and common buzzards in their flight altitudes and speeds, and in the wind conditions they encountered. Common buzzards had higher flight altitudes and were more selective of wind. Flight altitude was negatively related to the wind speed, which was most pronounced for common buzzards. Sparrowhawks had higher mean air- and cross-country speeds than common buzzards. Air- speed was negatively related, whereas ground and cross-country speeds were positively related to the tailwind component for both raptors. The differences between sparrowhawks and buzzards could to a large degree be explained by a larger dependence on thermal soaring among the common buzzards; a strategy associated with selectivity for favourable thermal and wind conditions during migratory flight. An additional important explanation for the interspecific differences was the habit of the sparrowhawks to combine migratory flight with hunting for prey, which makes it prone to fly at lower altitudes and use flapping flight to a much larger degree than common buzzards which do not forage during their migratory passage of the Falsterbo Peninsula [Current Zoo- logy 60（5）： 670-679, 2014].

Food Resource Partitioning in Alpine Weasel,Steppe Polecat and Upland Buzzard:Evidence from Stable Isotope Ratios

Based on mass balance theory and IsoSource program,stable carbon and nitrogen isotopic ratios revealed that small mammals (plateau pika,root vole and plateau zokor) contributed 26.8% and 27.0% and 29.2% to alpine weasel,steppe polecat and upland buzzard of carnivores as food respectively;adult passerine birds contributed 22.3%,47.7% and 69.1%,with hatchlings contributing 50.9%,25.6% and 1.70% to each respectively.δ 13 C values plotted against δ 15 N indicated significant partitioning in two-dimensional space among the three carnivores.It was reasonable to propose a food resource partitioning among alpine weasel,steppe polecat and upland buzzard,which partially revealed their co-existence mechanisms.

Use of DNA metabarcoding of bird pellets in understanding raptor diet on the Qinghai-Tibetan Plateau of China

Background:Diet analysis is essential to understanding the functional role of large bird species in food webs.Mor-phological analysis of regurgitated bird pellet contents is time intensive and may underestimate biodiversity.DNA metabarcoding has the ability to circumvent these issues,but has yet to be done.Methods:We present a pilot study using DNA metabarcoding of MT-RNR1 and MT-CO1 markers to determine the species of origin and prey of 45 pellets collected in Qinghai and Gansu Provinces,China.Results:We detected four raptor species[Eurasian Eagle Owl(Bubo bubo),Saker Falcon(Falco cherrug),Steppe Eagle(Aquila nipalensis),and Upland Buzzard(Buteo hemilasius)]and 11 unique prey species across 10 families and 4 classes.Mammals were the greatest detected prey class with Plateau Pika(Ochotona curzoniae)being the most frequent.Observed Shannon’s and Simpson’s diversity for Upland Buzzard were 1.089 and 0.479,respectively,while expected values were 1.312±0.266 and 0.485±0.086.For Eurasian Eagle Owl,observed values were 1.202 and 0.565,while expected values were 1.502±0.340 and 0.580±0.114.Interspecific dietary niche partitioning between the two spe-cies was not detected.Conclusions:Our results demonstrate successful use of DNA metabarcoding for understanding diet via a novel noninvasive sample type to identify common and uncommon species.More work is needed to understand how raptor diets vary locally,and the mechanisms that enable exploitation of similar dietary resources.This approach has wide ranging applicability to other birds of prey,and demonstrates the power of using DNA metabarcoding to study species noninvasively.

Habitat preferences of diurnal raptors in relation to human access to their breeding territories in the Balkan Mountain Range,Bulgaria

Background:In this study we examined the habitat preferences of three diurnal raptors in relation to human access.We aimed to identify the selection of breeding habitat by the Golden Eagle(Aquila chrysaetos),the Long-legged Buz-zard(Buteo rufinus),and the Peregrine Falcon(Falco peregrinus)in response to site accessibility by humans,and in turn,the response of these species to human presence.Methods:Data about the nest locations were collected.Analyses and maps were created using ArcGIS.The“least cost path”was defined using the Cost Path tool.Results:The lowest values of the Cost Path were established for Long-legged Buzzard and the highest values were estimated for Golden Eagle.Intermediate Cost Path values for Peregrine Falcon were found.Conclusions:The Long-legged Buzzard could be considered as the most tolerant to human presence in its breeding territories.The Golden Eagle have the lowest degree of tolerance and the Peregrine Falcon is ranked in an intermedi-ate position compared to the other two species,but closer to Golden Eagle.