Variation in the wing-clapping display of Clapper Larks

The pied plumage of the adult Black Sparrowhawk is rather exceptional in the genus Accipiter and it could be explained by functionality or by phylogenetic relationships. The moult pattern of museum specimens is presented, supplementing information from captive birds. The post-juvenile moulting sequence is similar to that of the Northern Goshawk. The moult of primaries starts at, or just after, the beginning of body moult; moult of the secondaries also starts early and progresses from three consecutive foci, and tail moult starts early but is less predictable. A few body feathers and tail feathers may remain in place until the second moult. The pied flank feathers appear at an early stage. Some adult specimens are in arrested annual moult. Two with definite serially-descendant moult were discovered; this is related to the fact that the species is known to be double-brooded. Serially descendant moult was not known in this species and is rarely mentioned in the genus. Possible functions of the pied plumage are discussed: crypsis, mimicry, hunting strategy, and sexual attraction. Its taxanomic status is obscure. Although the streaked juvenile plumage of the Black Sparrowhawk is similar to those of the Northern Goshawk A. gentilis, Meyer's Goshawk A. meyerianus and Henst's Goshawk A. hentsi, adult and juvenile plumages are variable within the genus, and thus are not a reliable indicator of taxanomic relationships.     

The decline of Common Kestrels Falco tinnunculus in a forested area of northern England: the role of predation by Northern Goshawks Accipiter gentilis

We have previously documented the decline of the Common Kestrel Falco tinnunculus over a 23‐year period in a large coniferous forest in northern England. Kestrels fed predominantly on Field Voles Microtus agrestis, which were most abundant in young plantations (1–11 years old). Over the 23 years, voles remained abundant in the study area, but their numbers fluctuated cyclically. Here we consider whether the decline of Kestrels was linked to predation by Northern Goshawk Accipiter gentilis. Goshawks first bred in the study area in 1973 and increased until 1989, after which numbers stabilized. We use a number of approaches to explore the role of Goshawk predation, all of which are correlative, but independent. First, there was a significant negative relationship between Kestrel and Goshawk numbers after controlling for a decline in vole habitat. Short‐eared Owls Asio flammeus, which also hunt by day, declined over the same period as Kestrels. Second, numbers of Tawny Owl Strix aluco and Long‐eared Owl Asio otus did not decline as Goshawk numbers increased. These two species are also vole‐dependent, but active by night, and less vulnerable to Goshawk attack. Third, six species of raptor comprised 4.5% of 5445 Goshawk prey items during the breeding season, but more Kestrels were killed than the combined total of all other raptors. Goshawks not only killed many adult Kestrels in early spring, prior to breeding, when it would have most impact on population levels, but there was also a temporal trend for predation on Kestrels to be inversely density‐dependent. Finally, we estimated that Goshawks removed more Kestrels than were recorded each spring in the study area. We interpreted this as indicating that immigrant Kestrels were being removed continually, mostly before they could breed. We conclude that the decline of Kestrels (and possibly Short‐eared Owls) was mainly due to predation by Goshawks. This study provides some of the strongest evidence yet of the role of predation in the hierarchical structuring of raptor communities.     

Prey preferences and recent changes in diet of a breeding population of the Northern Goshawk Accipiter gentilis in Southwestern Europe

Capsule: Northern Goshawk Accipiter gentilis diet has changed significantly since the 1980s, probably due to changes in populations of preferred prey species.

Aims and methods: To assess changes to the breeding season diet of the Northern Goshawk in southwest Europe over three decades. We examined prey remains at and around nests and assessed avian prey availability using point count and line transect surveys.

Results: During 2008–11, Goshawks mainly ate birds, with Feral Pigeons Columba livia f. domestica being the most important prey species. Goshawks preferred prey of 100?400?g and forest prey species to non-forest species. Goshawk diet has changed significantly over recent decades: 22% of current prey items belong to species that were not part of the diet in the 1980s. We suggest that these dietary changes reflect changes in the abundance of prey species of the preferred size caused by changes in land use leading to an increase in forest cover, new prey species colonization and changes in the abundance and management of domestic prey.

Conclusion: This study emphasizes that major transformations occurring in agroforestry systems are affecting the main preferred prey of important forest predators, which may have consequences for conservation of both the predators and their prey.     

Mitochondrial phylogenetics of the goshawk Accipiter [gentilis] superspecies

The Northern Goshawk Accipiter gentilis is a medium‐sized bird of prey inhabiting boreal and temperate forests. It has a Holarctic distribution with 10 recognized subspecies. Traditionally, it has been placed within the Accipiter [gentilis] superspecies, together with Henst's Goshawk A. henstii, the Black Sparrowhawk A. melanoleucus, and Meyer's Goshawk A. meyerianus. While those four taxa are geographically separated from each other, hence referred to as allospecies, their phylogenetic relationships are still unresolved. In the present study, we performed phylogenetic analyses on the Accipiter [gentilis] superspecies, including all recognized subspecies of all four allospecies, using partial sequences of two marker loci of the mitochondrial genome, the control region and the cytochrome b gene. We found a deep split within A. gentilis into two monophyletic groups, a Nearctic clade (three subspecies) and a Palearctic clade (seven subspecies). The Palearctic clade is closely related to A. meyerianus, and together these two were more closely related to the other Old World taxa A. henstii and A. melanoleucus, which in turn were reciprocally monophyletic sister species. As a consequence, A. gentilis as usually conceived (including all Holarctic subspecies) was non‐monophyletic. We found a strong genetic homogeneity within Palearctic A. gentilis despite the fact that it comprises seven subspecies distributed from the Atlantic coast in Western Europe to Eastern Siberia. Relationships between the four clades could not be resolved unambiguously. Our results, if confirmed by more integrative data, would imply a taxonomic revision of Nearctic A. gentilis into a separate allospecies, Accipiter [gentilis] atricapillus.     

Brutbiotop und Territorialit?t bei Habicht (Accipiter gentilis) und Rotmilan (Milvus milvus)

Zusammenfassung In einem Gebiet auf der Schwäbischen Alb von 432 km² mit weitgehend homogener Waldverteilung brüteten 13 Habicht- und 20 Rotmilanpaare. Die Horsthöhe über dem Boden lag bei beiden Arten oberhalb der Handbuchangaben. Eine Bevorzugung von Laubwaldhabitaten durch den Rotmilan war nicht erkennbar. Die regelmäßige intraspezifische Dispersion der Horstreviere beider Arten läßt auf das Vorhandensein intraspezifischer Territorialität schließen. Eine Regelmäßigkeit in der interspezifischen Dispersion war hingegen nicht erkennbar. Negative Einflüsse des Habichts auf den Reproduktionserfolg des Rotmilans waren ebenfalls nicht nachweisbar. Konkurrenz um Horstplätze zwischen Habicht und Rotmilan spielte im untersuchten Gebiet somit eine unbedeutende Rolle. Die Wirkung solcher Konkurrenz als ein für konstante Populationen allgemeingültiger Regulationsmechanismus nachKostrzewa et al. (1985) wird in Frage gestellt. Allein im Abstand des Horstes zum Waldrand bestand im Untersuchungsgebiet eine klare Trennung der Horstplatzansprüche beider Arten.

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Nesting habitat and territoriality in Goshawk (Accipiter gentilis) and Red Kite (Milvus milvus)

Summary Intraspecific and interspecific spacing of Goshawk and Red Kite nesting places were investigated in an area of 432 km² located in southern Germany. The area is characterized by a relatively homogeneous forest distribution. Nesting habitat data were collected over a period of four years. Thirteen breeding pairs of Goshawk und twenty breeding pairs of Red Kite were censused within the study area. The mean heights of nests above ground in both species were greater than those previously described (i. e.Cramp &Simmons 1980). The current view, that Red Kites prefer deciduous forest nesting habitats and deciduous nest trees, could not be confirmed.The regular intraspecific spacing of nesting places in both species indicates intraspecific territoriality. In contrast, no regularity in interspecific spacing could be detected. There was no noticeable influence of the Goshawk on the reproduction success of the Red Kite. Thus, competition for nesting places in the investigated area among Goshawk and Red Kite plays, if any, only a minor role. A factor seperating the two species with high significance is the distance from the nesting place to the nearest forest edge.In conclusion, the present study shows that competition for nesting places as a regulation mechanism, as proposed byKostrzewa et al. (1985), is unlikely.

     

GENERAL BIOLOGY OF SPECIES

Enderson , J. H. 1965. A breeding and migration survey of the Peregrine Falcon. Hudson , R. 1966. Adult survival estimates for two Antarctic petrels. Kobriger , G. D. 1965. Status, movements, habitats, and foods of Prairie Grouse on a sandhills refuge. Lindhe , U. 1966, (The choice of prey of Tengmalm's Owl (Aegolius funereus) in Lysksele Parker , S. A. 1963. A note on the habits of Mayrornis schistaceus Mayr (Muscicapide) of the Southwest Pacific. Parker , S. A. 1963. Nidification of the genus Melanocharis Sclater (Dicaeidae). Pitman , C. R. S. 1962. Notes on the African Finfoot Podica senegalensis (Vieillot) with particular reference to Uganda. Percy , (the late) Lord William 1963. Further notes on the African Finfoot, Podica senegalensis (Vieillot). Pitman , C. R. S. 1963. The breeding of the Great Spotted Cuckoo Clamator glandarius L. in Iraq and a note on the Iraq eggs of the Kashmir Magpie Pica pica bactriana Bp. Pitman , C. R. S. 1963. The nesting of the Black-bellied Seed-cracker, Pirenestes ostrinus in Uganda, and notes on its habitat and classification. Reid , B. 1965. The Adelie Penguin (Pygoscelis adeliae) egg. Skutch , A. F. 1966. Life history notes on three tropical American cuckoos. Stonehouse , B. 1966. Emperor Penguin colony at Beaufort Island, Ross Sea, Antarctica. Sulkava , P. 1964. (On the behaviour and food habits of the Sparrowhawk (Accipiter nisus) during the nesting season). Sulkava , S. 1964. (The Goshawk (Accipiter gentilis) and its feeding habits in south and central Finland.) Taylor , R. H. 1964. Adelie Penguin rookeries in the Ross Dependency. Walkinshaw , L. H. 1966. Summer biology of Traill's Flycatcher. Westerkov , K. 1965. Utilization of grit by Pheasants in New Zealand.     

SOME NOTES ON THE CAPE GANNET,Morus capensis

Tarboton, W. R. 1978. Breeding of the Little Banded Goshawk. Ostrich 49:132-143.

The behaviour and vocalizations of a pair of Little Banded Goshawks Accipiter badius during part of their breeding cycle is described. Both sexes built the nest. Two eggs were laid three days apart. The first egg was incubated for 52% of the day, but this increased to 90% when the clutch was complete, of which the female's share was 86% and the male's 4%. The second egg hatched after 29 days, 18 h. The female did not hunt during the incubation or early nestling period and was fed by the male who brought her, on average, 7,0 food objects per day. Lizards formed 73% of the 91 identified prey objects, and small birds, 24%. The female and chick, when 16 days old, were killed by a predator on the nest at night.     

Changes to Category C of the British List†

In its maintenance of the British List, the British Ornithologists’ Union Records Committee (BOURC) is responsible for assigning species to categories to indicate their status on the List. In 1995, the British Ornithologists’ Union (BOU) and the Joint Nature Conservation Committee (JNCC) held a conference on naturalized and introduced birds in Britain ( Holmes & Simons 1996 ). This led to a review of the process of establishment of such species and the terms that best describe their status ( Holmes & Stroud 1995 ) as well as a major review of the categorization of species on the British List ( Holmes et al. 1998 ). The BOURC continues to review the occurrence and establishment of birds of captive origin in Britain. This paper summarizes the status of naturalized and introduced birds in Britain and announces changes to the categorization of many on the British List or its associated appendices (Categories D and E): Mute Swan Cygnus olor Categories AC change to AC2 Black Swan Cygnus atratus Category E* – no change Greylag Goose Anser anser Categories ACE* change to AC2C4E* Snow Goose Anser caerulescens Categories AE* change to AC2E* Greater Canada Goose Branta canadensis Categories ACE* change to C2E* Barnacle Goose Branta leucopsis Categories AE* change to AC2E* Egyptian Goose Alopochen aegyptiacus Categories CE* change to C1E* Ruddy Shelduck Tadorna ferruginea Categories BDE* – no change Muscovy Duck Cairina moschata Category E* – alert JNCC Wood Duck Aix sponsa Category E* – no change Mandarin Duck Aix galericulata Categories CE* change to C1E* Gadwall Anas strepera Category A change to AC2 Mallard Anas platyrhynchos Categories AE* change to AC2C4E* Red‐crested Pochard Netta rufina Categories AE* change to AC2E* Ruddy Duck Oxyura jamaicensis Categories CE* change to C1E* Black Grouse Tetrao tetrix Categories AE – no change Western Capercaillie Tetrao urogallus Categories BC change BC3 Red‐legged Partridge Alectoris rufa Categories CE* change to C1E* Grey Partridge Perdix perdix Categories ACE change to AC2E Common Pheasant Phasianus colchicus Categories CE* change to C1E* Golden Pheasant Chrysolophus pictus Categories CE* change to C1E* Lady Amherst's Pheasant Chrysolophus amherstiae Categories CE* change to C6E* Black‐crowned Night Heron Nycticorax nycticorax Categories AE* – no change Sacred Ibis Threskiornis aethiopicus Category E – no change Red Kite Milvus milvus Categories AC change to AC3 White‐tailed Eagle Haliaeetus albicilla Categories ACE change to AC3E Northern Goshawk Accipiter gentilis Categories AE* change to AC3E* Rock/Feral Pigeon Columbia livia Categories AE* change to AC4E* Rose‐ringed Parakeet Psittacula krameri Categories CE* change to C1E* Barn Owl Tyto alba Categories AE* – no change Little Owl Athene noctua Category C change to C1     

Methyl Donor-Deficient Diet during Development Can Affect Fear and Anxiety in Adulthood in C57BL/6J Mice

DNA methylation is one of the essential factors in the control of gene expression. Folic acid, methionine and choline (methyl donors)–all nutrients related to one-carbon metabolism–are known as important mediators of DNA methylation. A previous study has shown that long-term administration of a diet lacking in methyl donors caused global DNA hypermethylation in the brain (Pogribny et al., 2008). However, no study has investigated the effects of a diet lacking in methyl donors during the developmental period on emotional behaviors such as fear and anxiety-like behavior in association with gene expressions in the brain. In addition, it has not been elucidated whether a diet supplemented with methyl donors later in life can reverse these changes. Therefore, we examined the effects of methyl donor deficiency during the developmental period on fear memory acquisition/extinction and anxiety-like behavior, and the relevant gene expressions in the hippocampus in juvenile (6-wk) and adult (12-wk) mice. We found that juvenile mice fed a methyl-donor-deficient diet had impaired fear memory acquisition along with decreases in the gene expressions of Dnmt3a and Dnmt3b. In addition, reduced anxiety-like behavior with decreased gene expressions of Grin2b and Gabar2 was observed in both the methyl-donor-deficient group and the body-weight-matched food-restriction group. After being fed a diet supplemented with methyl donors ad libitum, adult mice reversed the alteration of gene expression of Dnmt3a, Dnmt3b, Grin2b and Gabar2, but anxiety-like behavior became elevated. In addition, impaired fear-memory formation was observed in the adult mice fed the methyl-donor-deficient diet during the developmental period. Our study suggested that developmental alterations in the one-carbon metabolic pathway in the brain could have effects on emotional behavior and memory formation that last into adulthood.     

The mitochondrial cytochrome c oxidase I gene reveals phylogeographic structure in the African Goshawk Accipiter tachiro (Accipitridae)

We used a 298?bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) to examine sequence variation in (mostly) museum specimens of the African Goshawk Accipiter tachiro. Our results showed two clades with high bootstrap support in a phylogenetic analysis and two groups in a nonmetric multidimensional scaling (NMDS) analysis. Each of the two phylogenetic clades corresponded to one of the NMDS groups. One clade comprised haplotypes of the subspecies A. t. lopezi, A. t. macroscelides, A. t. toussenelli and A. t. canescens and corresponded to the morphospecies A. toussenelii. This taxon has a more north-western distribution. The second clade comprised haplotypes of the subspecies A. t. sparsimfasciatus, A. t. pembaensis and A. t. tachiro and corresponded to the morphospecies A. tachiro, which has a more south-eastern distribution. Furthermore, one branch corresponded to the morphospecies A. t. unduliventer, which is confined to the Ethiopian highlands. The genetic divergence observed among the three A. tachiro morphospecies appeared concordant with the ecological and morphological divergence and suggests the existence of three putative species. Within A. tachiro and A. toussenelii there is substantial morphological, but very little genetic, differentiation among subspecies.     

Female turnover rate differs between two Northern Goshawk Accipiter gentilis nesting areas,as revealed by DNA analysis of moulted feathers

The turnover rate of breeding Northern Goshawk Accipiter gentilis females in two study areas in southern Norway, which are assumed to experience different levels of illegal human persecution, was estimated using DNA extracted from moulted feathers, along with other characteristics. Female turnover rate over a 4‐year period for each nesting territory during 1990–2015 was significantly higher in Aust‐Agder County (31.9%; 23 territories), where hunters have long shown antipathy to Goshawks, than in Telemark County (17.3%; 25 territories). Turnover rate was not related to territory quality. The proportion of successful nesting attempts was lower in Aust‐Agder (70–75%) than in Telemark (82–84%), but for newly built nests, which are less likely to be known by hunters, the difference was not significant (77.4 vs 79.6%). The proportion of juvenile female Goshawks among recruits and in the total breeding population also did not differ between the two areas. Our findings support the notion that Goshawk persecution was higher in Aust‐Agder than in Telemark. We found that the use of phenotypic characteristics for individual recognition was successful in 96.2% of 130 comparisons of female Goshawks from two consecutive nesting attempts, when assessed using genetic markers.     

The effect of rainfall on the breeding behaviour of the Red Bishop,Euplectes orix

The behaviour and activities of 6 458 raptors (Accipitridae and Falconidae) and 1 947 Corvidae in the Karoo, South Africa, were recorded during the period January 1988 to June 2000 (n = 208 surveys) over a total distance of 90 012km. A significantly larger proportion of raptors and corvids were recorded foraging in road verges, or flying along roads than foraging or flying over rangelands. About 21% of all observations of crows feeding or foraging were associated with road-kills, whereas less than 2% of observations of feeding and foraging Accipitridae and Falconidae were associated with road-kills. The most frequent Accipitridae feeding on road-kills were Pale Chanting Goshawk (Melierax canorus), Yellow-billed Kite (Milvus migrans parasitus) and Jackal Buzzard (Buteo rufofuscus). There was no seasonal pattern in the number of crows feeding on roadkills, although there was a trend for more mammals to be killed on the roads, and thus more available food, in winter (June). It is likely that Accipitridae and Falconidae are attracted to roads by the availability of perches and the relatively productive road verges rather than the availability of road-killed animals, whereas crows may be attracted by road-kills as well.     

Habitat segregation and the insular syndrome in two congeneric raptors in New Caledonia, the White-bellied Goshawk Accipiter haplochrous and the Brown Goshawk A. fasciatus

The comparative distribution and abundance of the two congeneric goshawks of New Caledonia, the White-bellied Goshawk Accipiter haplochrous and the Brown Goshawk A. fasciatus vigilax , were studied on 100 1-km² sample quadrats spread randomly over the island. The White-bellied Goshawk is a well-differentiated endemic forest-dwelling species, presumably of older origin than the morphologically little-differentiated island subspecies of the Brown Goshawk, which is restricted to open habitats. The two species exhibit ecological characteristics attributed to the so-called insular syndrome; these characteristics were more pronounced in the White-bellied than in the Brown Goshawk. The densities of both species were much higher than any density of the same or similar species ever recorded on a continent. Their habitat and foraging niches were broad. The two species were clearly segregated by habitat, their distribution overlapping only in semi-forested lowland areas where the White-bellied tended to encroach more on the habitat of the Brown Goshawk than the reverse. Possible determinants of their abundance, niche breadth and interspecific segregation are discussed, as well as the consequences for their conservation. The occurrence in New Caledonia of two additional congeneric species recently extinct and the existence of three other pairs of congeneric bird species with similar relationships are also emphasized.     

Superpredation patterns in four large European raptors

Predatory interactions among top predators, like superpredation or intraguild predation (IGP), can influence community structure. Diurnal raptors occupy high trophic levels in terrestrial food webs, and thus can regulate the presence of mesopredators. We studied superpredation (the killing and eating of another predator) in four large European raptors. We gathered 121 dietary studies, totalling 161,456 prey for the Goshawk Accipiter gentilis L., Golden Eagle Aquila chrysaetos L., Bonelli’s Eagle Aquila fasciata Vieillot, and Eagle Owl Bubo bubo L. Results showed that superpredation: (1) is a widespread interaction in large raptors, but it can vary according to the top predator species; (2) is not an important energetic resource for large raptors, but rather seems mostly related to diet diversification when the main prey decreases; (3) is spatially clustered reflecting habitat heterogeneity, but shows no temporal or large-scale spatial trends; and (4) it is associated with lower breeding success of the top predator species. These findings support the food stress hypothesis as the main driving force behind increases in superpredation and IGP in raptors, with the decrease in breeding performance as a side effect. Superpredation by large raptors deserves future research to understand its effects on mesopredators, because on one hand it might contribute to promote biodiversity, while on the other hand, it can sometimes represent an additional risk for small populations of endangered mesopredators.     

Schwermetalle in Federn von Habichten (Accipiter gentilis) aus unterschiedlich belasteten Gebieten

Zusammenfassung Mit standardisierten Habicht-Mauserfedern läßt sich die Schwermetallbelastung von Landschaftsausschnitten repräsentativ erfassen, wie der Vergleich mit auf physikalisch-technischem Weg ermittelten Depositionsraten aus dem gleichen Untersuchungsgebiet bestätigt. Zwischen den Cadmium-, Blei- und Kupfergehalten in standardisierten Habicht-Mauserfedern und den gemessenen Depositionsraten dieser Elemente besteht eine signifikante Korrelation. Die einzelnen Handschwingen zeigten unterschiedlich hohe Cadmium-, Blei- und Kupfergehalte, abhängig von ihrer Stellung im Flügel. Auch Federfahnen wiesen eine charakteristische Cadmium- und Bleiverteilung auf. Die exogene Auflagerung von Schwermetallen aus der Atmosphäre auf/in die Federfahnen wird diskutiert.

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Heavy metals in Goshawk (Accipiter gentilis) feathers from differently polluted areas

Summary Standardized moulted feathers of Goshawks are used as biomonitors to indicate heavy metal pollution of areas. There is a strong correlation between the cadmium, lead and copper content of this feathers and the wet deposition rate, measured by wet deposition samplers. The distribution of lead, cadmium and copper in different primaries and in other feathers are shown. The exogenous deposition of this heavy metals from the atmosphere on/into the feather vanes are discussed.

     

The influence of human and goshawk Accipiter gentilis activity on wood-pigeons Columba palumbus at brassica feeding sites

Humans caused more than half the disturbance of wood-pigeons, Columba palumbus, from roadside brassica feeding sites. The birds always flew away from pedestrians, cyclists and horsemen, but often remained feeding when closed vehicles passed. The pigeons resettled immediately on the same feeding site after 23% of goshawk, Accipiter gentilis, attacks, and birds were feeding there later the same day after nearly half the attacks. They resettled immediately after a similar proportion (19%) of the times they were approached by humans on foot, and rarely fed in fields where people were working. The shorter the time pigeons had spent feeding before an interruption, the sooner they returned after it. This probably reflected the level of their crop food reserves. This behaviour should minimise the effect of short duration disturbance, as caused by goshawk attacks, on wood-pigeons feeding at brassica sites. Goshawk attacks did not cause a reduction in pigeon pecking-rate. Pigeons feeding in roadside fields tended to avoid the side nearest to the road, but not parts of fields adjoining walls and hedges which could have provided cover for predatory attacks. It is concluded that scaring techniques based on man himself are more promising than use of the goshawk in protecting crops against wood-pigeons.     

Honey Buzzard Pernis apivorus nest‐site selection in relation to habitat and the distribution of Goshawks Accipiter gentilis

The selection of a suitable nest‐site is critical for successful reproduction. Species' preferences for nest‐sites have presumably evolved in relation to local habitat resources and/or interactions with other species. The importance of these two components in the nest‐site selection of the Eurasian Honey Buzzard Pernis apivorus was assessed in two study areas in eastern Austria. There was almost no difference in macro‐ and micro‐habitat features between nest‐sites and random plots, suggesting that Honey Buzzards did not base their choice of nest‐site on habitat characteristics. However, nests were placed significantly further from nests of Northern Goshawk Accipiter gentilis than would be expected if nest‐sites had been chosen at random. Furthermore, in one study area Honey Buzzards appeared to favour areas close to human settlements, perhaps indicating a mechanism to avoid Goshawks, which tend to avoid the proximity of humans. No habitat variable was significantly associated with the loss of Honey Buzzard young, but predation was higher in territories closer to breeding pairs of Goshawks at both study sites. Although Honey Buzzards are restricted to nesting in forests, their choice of nest‐site therefore appears to be largely dictated by the distribution of predators. Studies of habitat association may yield misleading results if the effects of predation risk on distribution are not considered.     

Kleinfl?chen und Me?stellen zur Kalkulation gro?fl?chiger Brutvogelbest?nde:Buteo buteo undAccipiter gentilis in Schleswig-Holstein

Zusammenfassung Großflächige Bestandszahlen vieler Vogelarten sind nur über Teilerfassungen zu erhalten. Quantitative Gitterfeldkartierung mit Konfidenzintervallberechnung ermöglicht, Bestandsgrößen ohne Schätzanteile zu ermitteln und die Größen der Stichproben zu disponieren (Abb. 2). Die Kalkulation des Mäusebussard-Bestandes für Schleswig-Holstein mit 15 % an Probefläche beträgt 2891 Paare (Intervall 88–112 %), mit 6 % Probefläche nur geringfügig abweichend 3048 (oder gerundet 2400–3700) Paare innerhalb des 95%-Konfidenzintervalls (Abb. 2). Auf einer kleineren Bezugsfläche (1195 bzw. 750 km²) erbrachten Kalkulation mit 34 % Probefläche und Totalkontrolle nah beieinanderliegende Ergebnisse. Dabei lag das 95%-Konfidenzintervall im Rahmen der langfristigen Schwankungsbreite des Mäusebussards. An Meßstellen mit 37 % des Mäusebussard-Bestandes auf 360 km² ließ sich die Dynamik ermitteln (Abb. 3). Die Kalkulation des Habicht-Bestandes für Schleswig-Holstein mit 19 % Probefläche beträgt 366 Paare (Intervall 82–118 %=300–432 Paare, Abb. 2). Die Bestandsabnahme des Habichts (Abb. 3) nach 1980 scheint mit den Tötungen dieser Art zusammenzuhängen.

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Calculating breeding bird populations by sampling small areas:Buteo buteo andAccipiter gentilis in Schleswig-Holstein, FRG

Summary Population size estimates of various bird species in large areas can only be obtained by sampling small and representative plots. Quantitative grid mapping (1=3.75 km, A=14.06 km²) and the calculation of confidence intervals allow the size of the population to be determined. The size of the sample plots can be determined using the curve of the confidence limits (fig. 2). In Schleswig-Holstein, the breeding population of the Buzzard (13 600 km² excluding coastal meadows), is calculated at 2.891 pairs (confidence limits 88–112 %), based on sample plots (15 % of the total area, fig. 1). Based on only 6 % of the representative sample plots similar results can be found: 3,048 pairs. That is within the 95 % confidence limits of the estimation on the basis of 15 % (fig. 2). An investigation of 34 % of a smaller area (750 km²) revealed almost the same results as an investigation of the total area. The 95 % confidence limits lie within the long-term population dynamics of the Buzzard. The population dynamics can be determined by constant assessment sites (distributed over an area of 360 km²) containing 37 % of the Buzzard population (fig. 3). For the Goshawk population the same calculation, based on 19 % of the sample plots, shows 366 pairs for Schleswig-Holstein (95 % confidence limits 82–118 %=300–432 pairs). The decrease in the population of the Goshawk after 1980 seems to be associated with persecution.

     

Killing of raptors on grouse moors: evidence and effects

Owing to the intensity of game management in Britain, managers of grouse moors have illegally killed raptors to increase the numbers of Red Grouse Lagopus l. scotica available for shooting. This paper summarizes evidence for the recent scale of illegal raptor killing on grouse moors and its effects on populations. It provides insights into how raptors themselves respond demographically to different levels of killing. Over Britain as a whole, most raptors have increased and expanded considerably since the 1970s, in response to reduced killing and nest destruction, and the diminished impacts of organo‐chlorine pesticides; however, in recent decades the populations of some species have declined on and around grouse moors. This is widely evident in Hen Harrier Circus cyaneus, Peregrine Falcon Falco peregrinus and Golden Eagle Aquila chrysaetos populations and in more restricted areas also in Northern Goshawk Accipiter gentilis and Red Kite Milvus milvus populations, in all of which illegal killing has been sufficient to affect numbers over wider areas. The evidence consists mainly of: (1) greater disappearance of nesting pairs, lower breeding densities or reduced occupancy of apparently suitable traditional territories on grouse moors compared with other areas; (2) reduced nest success compared with other areas; (3) reduced adult survival compared with other areas; (4) reduced age of first breeding, reflecting the removal of adults from nesting territories and their replacement by birds in immature plumage; (5) greater levels of disappearance of satellite‐tracked birds on grouse moors than elsewhere; and (6) the finding of poisoned baits and traps, and shot or poisoned carcasses of raptors. Not all these types of evidence are available for every species, and other types of evidence are available for some. The Common Buzzard Buteo buteo is currently the most numerous raptor in Britain and also seems to be killed in the greatest numbers. Other raptor species, including Merlin Falco columbarius, Common Kestrel Falco tinnunculus and Eurasian Sparrowhawk Accipiter nisus which nest on or near grouse moors, have little or no significant impact on grouse and are killed less often or not at all. In the absence of illegal killing, some raptor species breed as well or better on grouse moors than in other habitats. Merlins, in particular, seem to thrive on grouse moors, benefiting from the management involved (including predator control). Other aspects of illegal raptor killing are discussed, including suggestions for ways in which it might be reduced.     

Evaluation of Trail-Cameras for Analyzing the Diet of Nesting Raptors Using the Northern Goshawk as a Model

Diet studies present numerous methodological challenges. We evaluated the usefulness of commercially available trail-cameras for analyzing the diet of Northern Goshawks (Accipiter gentilis) as a model for nesting raptors during the period 2007–2011. We compared diet estimates obtained by direct camera monitoring of 80 nests with four indirect analyses of prey remains collected from the nests and surroundings (pellets, bones, feather-and-hair remains, and feather-hair-and-bone remains combined). In addition, we evaluated the performance of the trail-cameras and whether camera monitoring affected Goshawk behavior. The sensitivity of each diet-analysis method depended on prey size and taxonomic group, with no method providing unbiased estimates for all prey sizes and types. The cameras registered the greatest number of prey items and were probably the least biased method for estimating diet composition. Nevertheless this direct method yielded the largest proportion of prey unidentified to species level, and it underestimated small prey. Our trail-camera system was able to operate without maintenance for longer periods than what has been reported in previous studies with other types of cameras. Initially Goshawks showed distrust toward the cameras but they usually became habituated to its presence within 1–2 days. The habituation period was shorter for breeding pairs that had previous experience with cameras. Using trail-cameras to monitor prey provisioning to nests is an effective tool for studying the diet of nesting raptors. However, the technique is limited by technical failures and difficulties in identifying certain prey types. Our study also shows that cameras can alter adult Goshawk behavior, an aspect that must be controlled to minimize potential negative impacts.