Differential range use between age classes of southern African Bearded Vultures Gypaetus barbatus

Bearded Vulture Gypaetus barbatus movements were investigated in southern Africa to determine whether an individual's age, sex or breeding status influenced its ranging behaviour and to provide the information required to guide conservation activities. Data from satellite transmitters fitted to 18 individuals of four age classes were used to determine range size and use. Because of the nature of the movements of marked individuals, these data could be used to determine the overall foraging range of the entire population, which was estimated to be 51 767 km 2 . Although juvenile, immature and sub-adult birds used different parts of the overall range, their combined foraging range was 65% (33 636 km 2 ) of the overall range. Average adult home ranges (286 km 2 ) were only around 1% the size of the average foraging ranges of non-adults (10 540 -25 985 km 2 ), with those of breeding adults being even smaller (95 km 2 ). Home ranges of breeding adults did not vary in size between seasons but adults utilized their home range more intensively whilst breeding, moving greater distances during the incubation and chick hatching period. Range size and use increased as non-adults aged. Immatures and sub-adults had larger range sizes during winter, but range use of non-adults did not vary seasonally. Range size and use did not differ between the sexes in any of the age classes. Information on home range size and use enables specific areas within the species' range to be targeted for management planning, education and conservation action

Female begging calls reflect nutritional need of nestlings in the hen harrier Circus cyaneus

BACKGROUND: Most birds exhibit bi-parental care with both sexes providing food for their young. Nestling signal food needs through begging. However, for some species, males rarely visit the nest, so have limited opportunity for gaining information directly from the chicks. Instead, females beg when males deliver food. We tested whether this calling signalled nutritional need and specifically the needs of the female (Breeder Need hypothesis) or that of their chicks (Offspring Need hypothesis). RESULTS: We observed begging and provisioning rates at 42 nests of hen harrier (Circus cyaneus) in Scotland, explored the factors associated with variation in begging rate and the relationship between begging and provisioning. We also tested the impact of food on begging and provisioning through a feeding experiment. Female begging rate increased up to a chick age of 3 weeks and then tailed off. In addition, begging increased when broods were large. CONCLUSIONS: Our data provided support for the Offspring Need hypothesis. At nests where adlib food was provided females reduced their begging rate. These patterns suggested that female begging was an honest signal of need. However, begging continued even with adlib food and was only weakly associated with greater provisioning by males, suggesting that these calls may also play an additional role, possibly reflecting sexual or parent-offspring conflict

Diversionary feeding as a means of reducing raptor predation at seabird breeding colonies

Predation can limit bird populations, especially in ground-nesting and colonial species. Solutions are usually available to reduce the impacts of predation if the predator is non-native or not legally protected (e.g. predator control or exclusion). However, when the predator is protected by law (e.g. raptors) potential solutions are limited. If predator and prey are both species of conservation concern this can bring the conservation of these species into conflict. Diversionary feeding (DF) is a potential solution, whereby predators are provided with food to reduce their motivation to hunt. The efficacy of DF has rarely been tested thus, in this paper, we test the efficacy of DF to reduce predation by kestrels, Falco tinninculus, a protected and declining raptor, on little tern chicks, Sternula albifrons, a protected seabird, within an internationally important colony in eastern England. We used a 17-year dataset of annual estimates of little tern productivity and counts of kestrel predation events to compare years with and without DF (DF = 6 years). During a four-year period of more intensive monitoring efforts, where we employed DF at focal kestrel nests in alternate years, we quantified the rates of kestrel predation at the colony and prey provisioning rates at kestrel nests. Predation rates were 47% lower and productivity of little terns doubled in years when kestrels were fed. Intensive monitoring showed that predation rates by kestrels at the colony were 88% lower in the two years when kestrels were fed. Provisioning rates of all wild prey and little tern prey, was 3.4 and 6.2 times lower in DF years and the likelihood of little tern chicks being provisioned at nests was lower when alternative wild prey were provisioned. DF is an effective tool to reduce predation and increase productivity of little tern colonies threatened by kestrel predation. The magnitude of these effects on little tern productivity was sufficient to promote population increases. Raptor conservation has resulted in increasing populations of many species and it is expected that predator-prey conflicts is likely to increase. DF could be an important tool to manage these conservation issues, but further tests of the efficacy in different predator-prey systems will be needed

Ranging Behaviour of Verreaux's Eagles during the Pre-Breeding Period Determined through the Use of High Temporal Resolution Tracking

Information on movement ecology is key in understanding the drivers and limitations of life history traits and has a potential role in indicating environmental change. Currently we have a limited understanding of the parameters of movement of territory-bound raptors, which are sensitive to environmental change. In this study we used GPS tracking technology to obtain spatially (within 3 m) and temporally ( c . 3 mins) high-resolution movement data on a small sample of Verreaux's eagle Aquila verreauxii during the pre-laying period ( n = 4) with one additional example during the chick rearing period. We present GPS-derived home range estimates for this species and we examine temporal (timing, duration, frequency and speed) and spatial (total path length and maximum distance from nest) patterns of trips away from the nest. For eagles tagged in the agriculturally developed Sandveld region ( n = 3), which is made up of a mosaic of land use types, we also undertook a habitat selection analysis. Home ranges were small and largely mutually exclusive. Trip activity was centred around midday, which is likely to be related to lift availability. Our habitat selection analysis found that eagles selected for near-natural and degraded habitat over natural or completely modified areas, suggesting that these eagles may have benefitted from some of the agricultural development in this region. Although our sample sizes are small, the resolution of our tracking data was essential in deriving this data over a relatively short time period and paves the way for future research

Ranging behaviour of hen harriers breeding in Special Protection Areas in Scotland

Capsule: Breeding female Hen Harriers hunted mostly within 1 km from the nest and males mostly within 2 km. Aims: To quantify temporal and spatial variation in home-range sizes and hunting distances of breeding male and female Hen Harriers. Methods: We radio-tracked ten breeding harriers (five males and five females) in three Special Protection Areas in Scotland between 2002 and 2004. Results: Male Hen Harriers travelled up to 9 km from nests but had a home-range size that averaged only 8 km2 (90% kernel); average home-range size for females was 4.5 km2. Hunting distances did not vary throughout the season. No significant differences were found among study areas, but there was large individual variability. Conclusion: Our results provide information on foraging harriers to support management: actions within 1 km of nesting sites will favour both sexes, and within 2 km will mostly favour males. Our data also suggest overlap between foraging areas of neighbouring birds. Thus, there is the potential for good foraging areas to be utilized by multiple breeding pairs

Differential Haemoparasite Intensity between Black Sparrowhawk (Accipiter melanoleucus) Morphs Suggests an Adaptive Function for Polymorphism

Recent research suggests that genes coding for melanin based colouration may have pleiotropic properties, in particular conveying raised immune function. Thus adaptive function of polymorphism may be associated with parasite resistance. The black sparrowhawk Accipiter melanoleucus is a polymorphic raptor with two morphs. Over most of its range the light morph is commonest, however within the recently colonised Western Cape of South Africa the dark morph predominates. The species breeds in winter throughout South Africa, however unlike in the rest of the species' South African range, the Western Cape experiences a winter rainfall regime, where arthropod vectors which transmit haematozoan parasites may be more abundant. We hypothesise that the higher frequency of dark morph birds in this region may be due to their improved parasite resistance, which enables them to cope with higher parasite pressure. If so, we predict that dark morph black sparrowhawks would have lower parasite burdens than light morph birds. Within our population the prevalence of the two most common haematozoan parasites was high, with 72% of adults infected with Haemoproteus nisi and 59% of adults infected with Leucocytozoon toddi. We found no difference in prevalence for either parasite between adult morphs, or between chicks of different parental morphs. However, within adults infected with H. nisi, infection intensity was significantly higher in light morphs than dark morphs. This suggests that dark morphs have lower parasite loads than light morphs due to resistance rather than morph-specific habitat exploitation. Greater resistance to Haemoproteus parasites may therefore be one of the mechanisms through which dark morph black sparrowhawks have a selective advantage in this region and may explain why they are most common in our study area. In other regions, the cost to benefit ratio may be in favour of the light morph, where parasites are less abundant or virulent

Does timing of breeding matter less where the grass is greener? Seasonal declines in breeding performance differ between regions in an endangered endemic raptor

The timing of breeding can strongly influence individual breeding performance and fitness. Seasonal declines in breeding parameters have been often documented in birds, particularly in the Northern Hemisphere. Fewer studies have investigated whether seasonal declines in productivity vary in space, which would have implications for a species' population dynamics across its distributional range. We report here on variation in the timing of breeding in the Black Harrier (Circus maurus), an endangered and endemic raptor to Southern Africa. We investigated how key breeding parameters (clutch size, nesting success and productivity) varied with the timing of breeding, weather conditions (rainfall and temperature) and between contrasted regions (coastal vs. interior-mountain). Black Harrier onset of breeding extended over an 8-month period, with a peak of laying between mid-August and end of September. We show a marked seasonal decline in all breeding parameters. Importantly, for clutch size and productivity these seasonal declines differed regionally, being more pronounced in interior-mountain than in coastal regions, where the breeding season was overall shorter. Timing of breeding, clutch size and productivity were also partly explained by weather conditions. In coastal regions, where environmental conditions, in particular rainfall, appear to be less variable, the timing of breeding matters less for breeding output than in interior-mountain regions, and breeding attempts thus occurred over a longer period. The former areas may act as population sources and be key in protecting the long-Term population viability of this threatened endemic raptor. This study provides unique evidence for a regionally variable seasonal decline in breeding performance with implications for population biology and conservation.This study was funded by the NRF (National Research Foundation, South Africa; Grant no. 90582 to R.E.Simmons), by the DST-NRF Center of Excellence at the Percy FitzPatrick Institute, University of Cape Town, by CSIC (Consejo Superior de Investigaciones Cientificas- PIE 201330E106) and by private landowners and organizations. Particular thanks for economic support are due to BirdLife South Africa, Inkwazi and Wits Bird Club, “Golden Fleece Merino”, URC (University Research Council), Jakkalsfontein Private Nature Reserve, TOSS (Two Oceans Slope Soarers), Natural Research UK, Hawk Mountain (USA), the Peregrine Fund, Sven Carlsson-Smith, Nial Perrins, Chris Cory, Gisela Ortner and James Smith. We are also grateful to Graham Cumming to help M-S Garcia-Heras with financial support in 2014.Peer Reviewe

Colonization and extinction dynamics of a declining migratory bird are influenced by climate and habitat degradation

Uncovering the mechanisms involved in the decline of long-distance migrants remains one of the most pressing issues in European conservation. Since the 1980s, the British breeding population of Garden Warbler Sylvia borin has declined by more than 25%. Here we use data from repeated bird surveys of woodland sites in the 1980s and in 2003-2004 to show that, although the overall population declined between the two periods, the probability of occupancy for this species increased at high latitudes and decreased at low latitudes. Range shifts such as this arise from a change in the ratio of colonizations to extinctions at the range margins, and we therefore related colonization and local extinction at the patch level to concurrent changes in temperature and habitat. The probability of patch colonization by this species was significantly lower where the percentage cover of vegetation in the understorey had declined, reducing habitat quality for this species. The probability of local extinction was significantly correlated with increasing mean May temperature, which may reflect a change in phenology, making breeding conditions less suitable. Changed regimes of grazing and woodland management could be used to increase habitat suitability and thereby increase colonization probability at the local scale, which may in turn increase the probability of patch occupancy despite future climatic unsuitability