Conservation efforts for large raptors require robust estimates of fecundity, age at maturity and survivorship, and population trajectories are often particularly sensitive to change in adult survival rates. Our study estimated apparent survival rates in territorial range-holding Golden Eagles Aquila chrysaetos in Scotland, based on DNA extracted from moulted feathers to profile individuals genetically: the first study for this species using the method. Feathers were collected at or close to nest sites within 93 home ranges involving 136 territorial individuals, across four years (2006-2009), with repeat-sampling in 21 % of home ranges. Genetic profiles identifying individuals’ presence/absence were analysed to estimate annual apparent survival rates using Cormack-Jolly-Seber models. Our models included sex, as male survival was expected to be lower, and two regions, the Outer Hebrides and the Inner Hebrides/Highlands, that host largely separate sub-populations. Estimates of male annual apparent survival rates (0.774-0.808) were markedly lower than females in both regions (0.878-0.882), but encounter rates of males (0.441-0.454) were also lower than females (0.639-0.754), probably because males spend less time near nest sites. We recorded a few instances of breeding dispersal, mostly involving females moving to neighbouring territories. Our estimates of apparent survival were probably close to true natural survival but possibly reduced by some illegal killing in the Inner Hebrides/Highlands. Annual rates for females were similar to previous estimates derived for the same age/status class which utilised other methods but did not separate the sexes. The different field methods used to estimate large raptor survival have advantages and disadvantages. Genetic profiling allows survival estimation of territorial occupants, but its sampling focus around the nest site creates limits in applicability. In our study system, where eagles may be killed illegally before providing opportunities for feather collection, genetic profiling is poor for detection of persecution mortality, and GPS-tagging is better.

Where human-wildlife conflicts lead to illegal persecution, wide ranging impacts for recovering predator populations can ensue. They may include reducing vital rates such as reproduction as well as survival. Illegal activities and their impacts are difficult to quantify. Nonetheless, often linked to gamebird shooting management, illegal persecution of raptors notoriously occurs in the UK, in detriment to several species’ distributions and abundance. How its impact varies with population density deserves more study. We examined the impact of persecution proxies on reproductive traits of northern goshawks Accipiter gentilis in northern UK. We found no evidence of an effect of the persecution proxies or of rainfall on goshawk reproduction. However, there was a strong negative density-dependence effect on productivity. Despite the impact of persecution on reproduction being certainly underestimated in our data, the overall growth of the goshawk population indicates that it at least partially compensated for prevailing persecution levels. The observation that goshawks produced more chicks in low density neighbourhoods must have contributed to this compensation. Our study extends previous work by elucidating the spatial scale of density-dependence. This suggested that density effects extended beyond typical nearest neighbour distances, implying that individuals may be interacting and interfering with a wider section of the population than previously thought. Should the population continue to increase in size, density-dependence will probably play an increasing role in population regulation.

Birds of prey frequently feature in reintroductions and the hacking technique is typically used. Hacking involves removing large nestlings from donor populations, transferring them to captivity, feeding them ad libitum. Potentially, via the hacking method, stress of captivity and disruption of parental feeding may be detrimental. Alternatively, provision of ad libitum food may be advantageous. Although hacking has underpinned reintroduction project successes there has been no research on how the method may affect the health and nutritional status of translocated birds during captivity. We compared blood chemistry data from 55 young White-tailed Eagles, translocated from Norway as part of the species’ reintroduction to Scotland, from sampling soon after arriving in captivity and again (≈ 42 d later) before their release. Numerous significant differences between first and second samples were found, but no significant interactions showed that sexes responded similarly to captivity. According to hematological and biochemical metrics, individuals showed several changes during captivity, including in red blood cell parameters, plasma proteins and white cellular parameters related to the immune system, that indicated improved health status. Captivity with ad libitum food was associated with decreased urea and uric acid values: high values can indicate nutritional stress. Urea values became more normally distributed before release, indicating that ad libitum food had reduced nutritional differences between early nestlings in the season and later ones. Despite plentiful food, both sexes lost body mass before release, suggesting an inherent physiological mechanism to improve flight performance in fledglings. We conclude that hacking improved the health and nutritional status of released eagles which is likely to enable birds to cope with greater costs of exploratory behavior which they may require in reintroduction projects. In this context, we note the absence of survival differences between hacked and wild raptors in previous research.