D. Philip Whitfield

The association of grouse moor in Scotland with the illegal use of poisons to control predators

In the UK uplands, there is a conflict between the maintenance of high densities of red grouse (Lagopus lagopus scoticus) for sporting shoots and the conservation of birds of prey on grouse moors where shoots take place. Several authors have indicated that as a result of this conflict, illegal use of poisoned baits to control predators is more likely to occur on grouse moors, but this association has not been examined formally. Mapping a form of land management unique to grouse moors (‘strip muirburn’), we use a GIS analysis to show that records of illegal poison use from 1981 to 2000 were disproportionately associated with grouse moors in Scotland. The association between poisoning incidents in the uplands and grouse moors was stronger in later years of the study period. It is suggested that this was at least partly due to a decline in the illegal use of poisons away from grouse moors. There was no evidence of any temporal decline in poisoning incidents on grouse moors over the study period. This research indicates that illegal methods for controlling predators (including protected birds of prey) are associated with traditional field sports and points to the need for management action.

Factors constraining the distribution of Golden Eagles Aquila chrysaetos in Scotland: capsule Between 1992 and 2003 persecution appeared to be the main influential factor.

Capsule Between 1992 and 2003 persecution appeared to be the main influential factor. Aims To utilize temporal changes in the distribution and occupation of Golden Eagle territories in Scotland between the 1992 and 2003 national censuses to assess potential causes of regional and national population trends, by examining spatial associations with a number of potential constraints on the population. Methods The distribution of occupied and vacant territories in the 1992 and 2003 censuses were entered as layers in a Geographical Information System (GIS), along with boundaries of biogeographical regions (Natural Heritage Zones) for regional analyses. Additional GIS layers were created for potential factors that may constrain the eagle population: the distribution and abundance of persecution incidents, new commercial conifer forests, popular mountains for hillwalkers (as surrogates for recreational activity), and the density of sheep and Red Deer (as surrogates for carrion abundance), drawn from comparable time periods to the national eagle censuses. Analyses then looked for spatial associations between eagle territory status and those constraint factors that may have influenced change in territory status. Results We found little evidence to suggest that recreational disturbance was influential on the occupation of Golden Eagle territories, although some local effects may have occurred and further analyses are warranted. We could find evidence of only a limited number of territories having being abandoned recently due to the planting of commercial conifer forests. We also rejected the hypothesis that changes in territory occupation between national Golden Eagle censuses were influenced by change in carrion abundance. By contrast, results were consistent with the hypothesis that persecution was influential in the observed change in territory occupation between censuses, so that occupied eagle territories tended to decline where persecution was probably still influential and tended to increase where persecution had probably declined. Conclusion In accordance with earlier predictions based on models of the demographic influence of persecution, in the central and eastern Highlands where grouse moor management predominates, the eagle population continued to decline to levels where increasingly large areas of suitable habitat are unoccupied by breeding pairs.

Ranging distance of resident Golden Eagles Aquila chrysaetos in western Scotland according to season and breeding status

Capsule Home-range of resident pairs of Golden Eagle was usually smaller during a successful breeding season than during winter and during an unsuccessful breeding season. Aims To examine how Golden Eagles use space around their nests with respect to season and breeding status, and to compare home-range-use between a high and a low density region. Methods Nine adults in six mainland Argyll ranges were radiotracked between 1991 and 1996. On the island of Mull visual observations of range-use were obtained for five ranges between 1994 and 1998. Results Overall, Mull ranges were smaller than the Argyll ranges, reflecting the much higher range density on Mull. In both regions there were significant differences between ranging distances with season and breeding status. In general, ranging distances were smallest during breeding seasons when young were fledged. Conclusions Studies of range-use in Golden Eagles must be conducted across a 12-month period, as a minimum.

Extrapair paternity in the common sandpiper, Actitis hypoleucos, revealed by DNA fingerprinting

The prevalence of extrapair paternity in many socially monogamous passerines has not been mirrored in most monogamous nonpasserines studied to date. Here, we investigated the reproductive behaviour of a socially monogamous shorebird, the common sandpiper, using multilocus DNA fingerprinting. Given the high level of paternal care in the species, and the likely high costs in allocating care between kin and nonkin in species with precocial young, we predicted low levels of extrapair paternity similar to other monogamous shorebirds. We found the social mating system to be predominantly monogamous although one polyandrous pairing was identified. Of 83 offspring from 27 broods, 13 (15.7%) young from five (18.5%) broods were identified as being extrapair. There was no evidence of intraspecific nest parasitism or quasiparasitism. In this population, territorial intrusions were carried out largely by males but did not appear to be related to seeking extrapair copulations (EPCs). Seventy copulation attempts were observed and most were within-pair (84%). Six of eight EPC attempts occurred outside the territory of the females social mate. Copulation rates were significantly higher just before and during egg laying than at other times during the study. At least two females that reared extrapair young had associated with males other than their eventual mates on arrival, suggesting that some females use rapid mate switching as a mating tactic, facilitated perhaps by the asynchronous arrival among both sexes in this population. Why some female sandpipers mate promiscuously remains unresolved.

Natal and breeding dispersal in a reintroduced population of White‐tailed Eagles Haliaeetus albicilla

Capsule Natal dispersal distance was significantly shorter in males than in females. Aim To examine the correlates of variation in dispersal in a reintroduced population of White‐tailed Eagles Haliaeetus albicilla in western Scotland. Methods Observations of natal (or release) sites and subsequent breeding sites of individually marked birds were used to calculate natal dispersal distance (NDD; the distance between natal (or release) site and first breeding site) and breeding dispersal distance, which is the distance moved by adults between sites of reproduction. Results NDD was significantly shorter in males than in females. Male NDD did not change over the 25+‐year study as the population expanded. Female NDD appeared to increase over time. Brood size at fledging and fledging date were not associated with NDD in either sex. There was no evidence of an association between parent and offspring NDD. Breeding dispersal was uncommon and involved moves to neighbouring territories when it did occur. Conclusions In White‐tailed Eagles, like the vast majority of animals, most movements affecting gene flow and demography result from natal dispersal. Our finding that NDD was lower in males than in females was consistent with the hypothesis that males compete for resources in order to attract females, and hence there is a greater selective advantage for males to stay closer to their natal sites, whereas females choose between the available resources of different males and so can disperse further. The apparent increase in female NDD over time was probably because, when first reintroduced, all birds shared the same ‘natal’ (release) site and female NDD was initially constrained to follow male NDD (since males settle at breeding sites earlier than females). Later, however, greater female NDD could be expressed in an expanded population with greater range of natal and breeding sites. There was little evidence that NDD of White‐tailed Eagles in western Scotland is being affected by increasing population density, suggesting that carrying capacity is far from being realized.

Using spatial analyses of bearded vulture movements in southern Africa to inform wind turbine placement

Summary Concerns over CO2 emissions during energy generation and its effect on climate change have led to increases in the use of renewables, such as wind energy. However, there are also serious environmental concerns over this type of energy production due to its impacts on bats and birds. In southern Africa, bearded vultures have declined by >30% during recent decades. They are now regionally critically endangered with only around 100 active pairs remaining. This species is considered vulnerable to collision with wind turbines which are planned within their southern African range. In this study, we develop habitat use models using data obtained from 21 bearded vultures of different ages fitted with GPS tags from 2009 to 2013. We further refined these models by incorporating flying heights at risk of collision to predict important areas of use that may conflict with wind turbines. Adult and non-adult bearded vultures mostly used areas with high elevations and steep and rugged topography in the core area; adults tended to use areas in relatively close proximity to their nest sites, whereas non-adult birds used areas dispersed over the entire species range and were more likely to fly at risk-height in areas that were less used by adults. Altitudes of fixes of adults and non-adults showed that they spent 55% and 66% of their time, respectively, at heights that placed them at risk of collision. Examining the locations of two proposed wind farms in relation to our model of predicted ‘at risk’ usage suggested poor positioning. Indeed, one of these wind farms was located within the 1% of ‘worst’ (most heavily used) sites for non-adult bearded vultures suggesting that its current location should be reconsidered to reduce the impact on this vulnerable species. Synthesis and applications. We demonstrate the value of habitat use models for identifying intensively used areas, in order to greatly reduce conflicts with developments such as wind turbines. This tool is operable at the scale of regional and national development plans informed by the habitat use of potentially vulnerable species. Such models should provide important supplementary assessments of site-specific development proposals.

Juvenile Dispersal of White-Tailed Eagles in Western Scotland

Abstract In long-lived raptors with delayed maturity, the period between fledging and settlement on a breeding site may take several years and is poorly understood. In our study of a reintroduced population of White-tailed Eagles (Haliaeetus albicilla), we investigated movements during this transient (juvenile dispersal) phase of natal dispersal using records of wing-tagged birds. Maximum juvenile dispersal distance (JDD), as measured from natal (or release) sites to locations recorded prior to birds settling on a breeding site ranged from 18 to 200 km in different individuals. Observation records suggested that (1) the most extensive movements occurred in the first two years after fledging, (2) males initially dispersed further than females, but, in their second year, females tended to be further from their natal site than males, and (3) as breeding age approached, males were closer to their natal sites than were females. Maximum JDD did not differ between wild-bred and released (reintroduced) birds and there was no indication that it was correlated with subsequent recruitment to the breeding population. We also found no evidence that a birds fledging date, body size, or the brood size in which it was fledged affected maximum JDD. There was no suggestion that Scottish White-tailed Eagles showed seasonally dependent returns to their natal areas. Maximum JDD during the first two years after fledging and natal dispersal distance (i.e., straight-line distance between natal and first breeding sites) were positively correlated in both females and males. The implication of these results was that, well before reaching maturity, White-tailed Eagles used dispersal movements, at least in part, to assess potential breeding sites, and thus dispersal behaviors were not simply directed toward survival alone.

Status of Golden EagleAquila chrysaetosin Britain in 2003

Capsule The third complete survey of Golden Eagles in Britain found 442 pairs. Aim To investigate the population size, distribution and breeding success of Golden Eagles in Britain, for comparison with similar surveys in 1982–83 and 1992. Methods All known home-ranges were surveyed between January and August 2003, to record Golden Eagle presence, breeding attempts and productivity using a three-visit methodology. The first visits were made in January–March to look for the presence of eagles, the second in April–June to detect whether a breeding attempt was taking place and the third in July–August to establish breeding success. Results In total, 442 pairs were located, a slight increase on the numbers in 1982–83 and 1992. There was considerable variation in population trends at a regional level, with decreases since 1992 in the eastern and south-central Highlands but an increase in the Hebrides. The mean productivity in 2003 was 0.36 fledged birds/pair. There was significant variation in breeding success between regions with, as in previous surveys, productivity being highest in the eastern Highlands. Conclusion The British Golden Eagle population remains stable. There remain concerns regarding the future of this population, particularly due to the threat posed by illegal persecution, and these results provide some supporting evidence for concerns raised by previous analyses. Persecution related to grouse moor management could be depressing the population in the eastern Highlands, preventing expansion into suitable habitat still unoccupied, and may be reducing the pool of non-breeding adult ‘floaters’ which act as a buffer against adverse population impacts. However, the survey did detect increases in the Hebridean islands since 1992, which may be because of a reduction in persecution.

Status of Golden Eagle Aquila chrysaetos in Britain in 2003

ABSTRACT Capsule: A complete survey of Golden Eagles Aquila chrysaetos in Britain in 2015 found that the population had increased by 15% since 2003 to 508 territorial pairs. Aims: The survey aimed to investigate the population size, distribution and breeding success of Golden Eagles in Britain, and to compare results with similar surveys since the early 1980s. Methods: Every home range was visited on a minimum of three occasions between January and August 2015. First, to look for eagles or signs of their presence (January–March), then to look for evidence of breeding or further checks for occupation (April–June) and finally to record productivity of nesting pairs (July–August). Results: The figure of 508 territorial pairs represents a 15% increase in the population from 442 pairs in 2003. The proportion of home ranges occupied was 70%. The largest increases in the proportion of occupied home ranges were in south-central Highlands (71%), northern moors and flows (38%) and northwest Highlands (29%), with modest increases of up to 10% in the other regions. Productivity was lower in 2015 than in 2003, and there was significant variation in breeding success between regions. Conclusion: The British Golden Eagle population has increased since 2003, although the species is absent from England and Wales. The population now meets the abundance target identified to define favourable conservation status in Scotland, and while home range occupancy has increased there is regional variation, with some regions falling below the target levels. A combination of increased annual monitoring and tagging of eagles, as well as the introduction of new legislation, may serve as effective deterrents against persecution of eagles thus facilitating this population increase. However, concerns remain over low levels of home range occupancy particularly in the east Highlands, but also the proportion of sub-adult pairs holding territory in that region and in the south-central Highlands. Persecution associated with grouse moor management has been highlighted as a particular population constraint in both of these areas.

Comparative nest habitat characteristics of sympatric White‐tailed Haliaeetus albicilla and Golden Eagles Aquila chrysaetos in western Scotland

Capsule Golden and White‐tailed Eagles selected different habitats for nesting. Aim To investigate differences in nesting habitat used by sympatrically breeding eagles in western Scotland, following reintroduction of White‐tailed Eagles from 1975 onwards. Methods Nest‐site locations from national surveys in 2003–05 were entered into a geographical information system (GIS) in order to measure a set of geographic parameters for each nest site. Binary logistic regression with backwards deletion of non‐significant terms was used to derive minimum adequate models at two spatial scales of the likelihood of an eagle nest belonging to one species or the other. We compared changes in occupancy between 1992 and 2003 of Golden Eagle territories inside and outside a GIS model of potential White‐tailed Eagle habitat and according to proximity to White‐tailed Eagle nests. Results White‐tailed Eagles nested at lower altitudes than Golden Eagles, in more wooded habitats with more open water close by, tending to nest in trees where these were present. There were 3359 km2 of potential White‐tailed Eagle nesting habitat within 25 km of existing White‐tailed Eagle nests, containing 54 Golden Eagle territory centres, but we found no difference in change of occupancy for Golden Eagle territories close to White‐tailed Eagles compared with those further away. Conclusion White‐tailed and Golden Eagles appear to partition nesting habitat in the west of Scotland by altitude. This corresponds with behaviour in western Norway and with the situation described in historical accounts of nest‐sites in western Scotland prior to extinction of White‐tailed Eagles. It is also consistent with recent studies showing little overlap in breeding season diet of Golden and White‐tailed Eagles in western Scotland, and likely partitioning of foraging habitat by altitude. We conclude that the likelihood of competitive exclusion is less than previously suggested.