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As their numbers increase, concerns exist about the possible negative impact of Pied Crows on other species and crows have been labelled a 'native invader'. However, little is known about the impact of crows on other species and few data exist describing the abundance of crows in the landscape, or how this abundance might change. Here we present some of the first estimates of Pied Crows in two protected areas in South Africa.

Successful reintroduction programmes are usually defined by an increase in size and extent of the new population after a given period of time. Among studies of birds, these population estimates are often focused on the monitoring of nesting attempts and productivity. For many raptors, however, this approach can overlook a large number of non-breeding adults and immature birds leading to underestimation of population size and reproductive potential. A more thorough approach is to generate assessments of total population size. In this study we used a line transect survey methodology and multiple covariate distance sampling to assess the change in population size of a reintroduced raptor species, Red Kite Milvus milvus, across a 2600 km2 area of central southern England. Surveys were performed in spring and autumn between 2011 and 2016 in an area 45 km to the south of the initial English reintroduction project which started 25 years previously. Survey routes avoided using roads where possible to counter the potential attraction that such landscape features may have (e.g. increased food availability, perches etc.). The use of roads was unavoidable in some instances; however, we found no evidence of Red Kite attraction to these landscape features when comparing distances of observations from stretches along roads with 5000 randomly-generated ocations. Distance of detection was influenced by bird activity (greatest when the bird was on the ground or interacting with other birds) and extent of woodland but not by time of day, seasonality or when comparing between years. During the five years, estimated population size doubled from approximately 490 to 1100 individuals; a density of one Red Kite per 2.5–3.5 km2. This suggests an increase in the breeding population in the study area from c. 95 to 174 pairs. During the study, rate of population growth was not uniform; rapid growth was recorded in years two and three followed by a slowing over the last two years of the study. While an overall increase in population and availability of suitable nesting habitat across south-eastern England indicates that there is still potential for expansion of the Red Kite breeding population, other factors are potentially limiting this growth.

We understand little about the energetic costs of flight in free-ranging birds; in part since current techniques for estimating flight energetics in the wild are limited. Accelerometry is known to estimate energy expenditure through body movement in terrestrial animals, once calibrated using a treadmill with chamber respirometry. The flight equivalent, a wind tunnel with mask respirometry, is particularly difficult to instigate, and has not been applied to calibrate accelerometry. We take the first steps in exploring a novel method for calibrating accelerometers with flight energy expenditure. We collected accelerometry data for Harris’s Hawks Parabuteo unicinctus flying to varying heights up to 4.1 m over a small horizontal distance; the mechanical\ud energy expended to gain height can be estimated from physical first principles. The relationship between accelerometry and mechanical energy expenditure was strong, and while a simple wing flapping model confirmed that accelerometry is sensitive to both changes in wing beat amplitude and frequency, the relationship was explained predominately by changes in wing beat frequency, and less so by changes in amplitude. Our study provides initial, positive evidence that accelerometry can be calibrated with body power using climbing flights, potentially providing a basis for estimating flapping flight metabolic rate at least in situations of altitude gain.

Capsule: Distance sampling identified an increase in estimated population size of Common Buzzards Buteo buteo in central southern England between 2011 and 2016 of more than 50%. The rate of population growth slowed in later years.\ud Aims: To assess the utility of a targeted distance sampling protocol to derive seasonal and annual\ud population estimates for Common Buzzards across an area of southern England.\ud Methods: We used a line transect survey methodology and multiple covariate distance sampling to assess population density and abundance of Common Buzzards in spring and autumn between 2011 and 2016 across a 2600 km2 area of central southern England.\ud Results: Estimated population size increased by more than 50%, from approximately 2900 to 4500 individuals, across the period in a trend similar to that shown by Breeding Bird Survey data.\ud Discussion: A slowing of the growth in population size of Common Buzzards in central southern England suggests that the species may be approaching carrying capacity in this area. These results also suggest that currently employed broad scale survey methodologies adequately reflect the general population trends for this species. Our data provide the first published estimates of the Common Buzzard population in central southern England derived from direct empirical assessment.

African White-backed vultures Gyps africanus are Critically Endangered, mainly due to mortality from poisoning, but the species also exhibits variable breeding productivity that may partially be explained by nest failure due to predation. Pied crows Corvus albus have been implicated as nest predators, but because there is no evidence linking Pied crows to low breeding productivity of White-backed vultures, we used a combination of dummy eggs (n = 14) and camera traps on active nests (n = 10), to investigate what species visit White-backed vulture nests (both active and abandoned) and predate on their eggs. We recorded 47 egg predation events, of which 37 (79%) were attributable to Pied crows, while other predators (unidentified large raptors, White-backed vultures and Vervet monkeys) were recorded interacting with eggs five times in total; mobbing by Pied crows of incubating vultures increased the probability vultures would abandon their nest but crows did not eat abandoned eggs as soon as they were available. Further studies are needed across a wider range of vulture breeding areas to contextualise these findings both in terms of breeding productivity and the significant risks of mortality faced by vultures from poisoning and other threats.

Book Title: Wildlife forensic investigation: principles and practiceBook Author: Cooper, J.E. & Cooper, M.E.742 pages, numerous colour and B&W photographs, tables, 11 appendices, full bibliography, index. Oxford, Taylor & Francis Group. 2013. Hardback, £82 ISBN 978-1-4398-1374-4.

Hooded Vultures Necrosyrtes monachus are critically endangered but little is known of their year-round use of nests or whether other species usurp Hooded Vulture nest sites. We investigated visitation rates by Hooded Vultures and other species (including potential nest predators and usurpers) to examine their effect on Hooded Vulture breeding success. We present observations of 33 species recorded by camera traps at 12 Hooded Vulture nests over a total of 93 nest-months (2 095 nest-days). Several pairs of Hooded Vultures visited their nests regularly during the non-breeding season, some adding nesting material, highlighting that pairs visited their nest(s) year round. Egyptian Geese Alopochen aegyptiaca, potential usurpers of raptor nests, were present at occupied and unoccupied Hooded Vulture nests, but we recorded no usurpation of nests by Egyptian Geese and they had no impact on vulture breeding success. Hooded Vulture breeding failure was linked to two species only: camera-trap imagery recorded one case of predation of a vulture egg by a Chacma Baboon Papio ursinus, and one case of a Martial Eagle Polemaetus bellicosus predating a vulture nestling. We recommend expanding the Hooded Vulture nest monitoring programme to include more pairs.Keywords: Alopochen aegyptiaca, Chacma Baboon, Egyptian Goose, Hooded Vulture, Kruger-to-Canyons Biosphere Region, Martial Eagle, Necrosyrtes monachus, nest visitors, Papio ursinus, Polemaetus bellicosus

The visual fields of Aegypiinae vultures have been shown to be adapted primarily to meet two key perceptual challenges of their obligate carrion-feeding behaviour: scanning the ground and preventing the sun’s image falling upon the retina. However, field observations have shown that foraging White-headed Vultures (Trigonoceps occipitalis) are not exclusively carrion-feeders; they are also facultative predators of live prey. Such feeding is likely to present perceptual challenges that are additional to those posed by carrion-feeding. Binocularity is the key component of all visual fields and in birds it is thought to function primarily in the accurate placement and time of contact of the talons and bill, especially in the location and seizure of food items. We determined visual fields in White-headed Vultures and two species of carrion-eating Gyps vultures, and show that the visual field of White-headed Vultures have more similarities with those of predatory raptors (e.g. Accipitrid hawks), compared with the taxonomically more closely related Gyps vultures. We found that maximum binocular field width in White-headed vultures (30°) is significantly wider than Gyps vultures (20°). The broader binocular fields in White-headed Vultures probably facilitate accurate placement and timing of the talons when capturing evasive live prey.

Species occurring at low density can be difficult to detect and if not properly accounted for, imperfect detection will lead to inaccurate estimates of occupancy. Understanding sources of variation in detection probability and how they can be managed is a key part of monitoring. We used sightings data of a low-density and elusive raptor (white-headed vulture Trigonoceps occipitalis) in areas of known occupancy (breeding territories) in a likelihood-based modelling approach\ud to calculate detection probability and the factors affecting it. Because occupancy was known a priori to be 100%, we fixed the model occupancy parameter to 1.0 and focused on identifying sources of variation in detection probability. Using detection histories from 359 territory visits, we assessed nine covariates in 29 candidate models. The model with the highest support indicated that observer speed during a survey, combined with temporal covariates such as time of year and length of time within a territory, had the highest influence on the detection probability. Averaged detection probability was 0.207 (s.e. 0.033) and based on this the mean number of visits required to determine within 95% confidence that white-headed vultures are absent from a breeding area is 13 (95% CI: 9–20). Topographical and habitat covariates contributed little to the best models and had little effect on detection probability. We highlight that low detection probabilities of some species means that emphasizing habitat covariates could lead to spurious results in occupancy models that do not also incorporate temporal components. While variation in detection probability is complex and influenced by effects at both temporal and spatial scales, temporal covariates can and should be controlled as part of robust survey methods

Vultures provide critical ecosystem services, yet populations of many species have collapsed worldwide. We present the first estimates of a 30-year Pan- African vulture decline, confirming that declines have occurred on a scale broadly comparable with those seen in Asia, where the ecological, economic, and human costs are already documented. Populations of eight species we assessed had declined by an average of 62%; seven had declined at a rate of 80% or more over three generations. Of these, at least six appear to qualify for uplisting to Critically Endangered. Africa’s vultures are facing a range of specific threats, the most significant of which are poisoning and trade in traditional medicines, which together accounted for 90% of reported deaths. We recommend that national governments urgently enact and enforce legislation to strictly regulate the sale and use of pesticides and poisons, to eliminate the illegal trade in vulture body parts, as food or medicine, and to minimize mortality caused by power lines and wind turbines. Publisher PDF

The White-headed Vulture Trigonoceps occipitalis (WhV) is uncommon and largely restricted to protected areas across its range in sub-Saharan Africa. We used the World Database on Protected Areas to identify protected areas (PAs) likely to contain White-headed Vultures. Vulture occurrence on road transects in Southern, East, and West Africa was adjusted to nests per km2 using data from areas with known numbers of nests and corresponding road transect data. Nest density was used to calculate the number of WhV nests within identified PAs and from there extrapolated to estimate the global population. Across a\ud fragmented range, 400 PAs are estimated to contain 1893 WhV nests. Eastern Africa is estimated to contain 721 nests, Central Africa 548 nests, Southern Africa 468 nests, and West Africa 156 nests. Including immature and nonbreeding birds, and accounting for data deficient PAs, the estimated global population is 5475 - 5493 birds. The identified distribution highlights are alarming: over 78% (n = 313) of identified PAs contain fewer than five nests. A further 17% (n = 68) of PAs contain 5 - 20 nests and 4% (n = 14) of identified PAs are estimated to contain >20 nests. Just 1% (n = 5) of PAs are estimated to contain >40 nests; none is located in West Africa. Whilst ranging behavior of WhVs is currently unknown, 35% of PAs large enough to hold >20 nests are isolated by more than 100 km from other PAs. Spatially discrete and unpredictable mortality events such as poisoning pose major threats to small localized vulture populations and will accelerate ongoing local extinctions. Apart from\ud reducing the threat of poisoning events, conservation actions promoting linkages between protected areas should be pursued. Identifying potential areas for assisted re-establishment via translocation offers the potential to expand the range of this species and alleviate risk.