Abstract Electrocution is one of the main causes of unnatural mortality among European raptors and poses a significant threat to vulnerable species such as the red kite ( Milvus milvus ). This study assessed the combined effects of mitigation measures on hazardous power line infrastructure and the red kite reintroduction programme aimed at restoring its breeding population in Jaén (Andalusia, southern Spain), where it had previously become extinct as a breeding species in the early 2000s. Between 2021 and 2025, 186 individuals were released following habitat suitability assessment, of whom 181 were fitted with GPS transmitters to monitor survival and spatial ecology. In parallel, a high-risk power line previously associated with elevated raptor mortality was retrofitted with anti-electrocution devices across 48 pylons located within the release area of the tagged red kites. A total of 80 mortality events of monitored red kites were recorded during the study, of which 72 were assigned a cause. Natural mortality accounted for 54.2%, with predation as the dominant factor (n = 34). Anthropogenic causes represented 45.8%, mainly poisoning (n = 9) and electrocution (n = 8). Notably, 21 reintroduced individuals used the mitigated power line area, generating 802 GPS fixes, with no recorded mortality associated with these structures, indicating effective reduction of electrocution risk. Population recovery was rapid, transitioning from complete absence to three breeding pairs in 2023, six in 2024, thirteen in 2025, and twenty-two in 2026. These findings demonstrate that integrating targeted infrastructure mitigation with reinforcement-based reintroduction can substantially improve survival rates and accelerate population recovery, highlighting an effective conservation strategy for raptors in human-modified environments.
Abstract Electrocution on power lines is one of the main anthropogenic causes of mortality in birds of prey worldwide and represents a major conservation concern for long-lived raptor species. Because mortality is spatially aggregated, a relatively small number of dangerous pylons can account for a disproportionate share of electrocution events, suggesting that targeted mitigation strategies may substantially improve conservation efficiency. We evaluated the effectiveness of a collaborative mitigation agreement between the Andalusian Government and the main electricity company in southern Spain (ENEL-ENDESA) by analysing temporal changes in the prevalence of electrocution blackspots. Using the official long-term electrocution database of Andalusia, we compared the proportion of 10×10 km UTM grid cells classified as mortality blackspots in 2014–2019 and during implementation of the agreement (2020–2025). Blackspots were defined as grid cells with more than 10 electrocuted raptors (orders Accipitriformes, Falconiformes and Strigiformes) recorded during both study periods. The proportion of blackspot grid cells decreased from 14.9% (44/295) before the agreement to 7.3% (28/381) during the mitigation period, despite increased sampling effort in the latter period. Differences between periods were significant, and the estimated odds ratio (OR = 0.45; 95% CI: 0.27–0.74) indicated a reduction of approximately 45% in the odds of a grid cell being classified as a blackspot. Importantly, this reduction was achieved after retrofitting only 13,166 hazardous pylons, representing approximately 5.2% of the estimated dangerous poles in Andalusia. Our results demonstrate that scientifically guided, spatially targeted mitigation programs developed through coordinated collaboration between conservation authorities and electricity companies can efficiently reduce the risk of electrocution at the landscape scale and help lower extinction risk for some endangered predator species.
Abstract The population restoration of regionally extinct raptors is often challenging, especially in the initial establishment of the population. The endangered saker falcon ( Falco cherrug ) became extinct as a breeding species in Bulgaria since 1997 but has recently been reintroduced. The first breeding occurred in 2017, and currently six breeding territories are occupied. We investigated the parental behaviour of a breeding pair that successfully raised five fledglings in 2025. We aimed to quantify parental provisioning by sex, describe prey handling and food-transfer behaviour, and estimate prey demand. A total of 56 prey deliveries were recorded during 90.7 h of observation. European ground squirrels ( Spermophilus citellus ) were the primary prey, accounting for 85% of provisioning by the male and 92% by the female parent. In 46 food-provisioning events with ascertained hunting individual, the male captured the prey in 72% of the cases (female in 28%). Male-to-female food transfers were recorded in 15 cases, of which 8 were in the air and 7 in the nest. All but one prey items were brought to the nest decapitated. The female fed the chicks in 85% of cases (male in 15%). The average feeding duration was 14 ± 3.84 min. Based on the observed provisioning rates, we estimated that the pair and their offspring may have preyed on approximately 600 sousliks during the entire breeding season. Future research needs to focus on whether territorial pairs in Bulgaria are resident throughout the winter, on studying hunting behaviour outside the breeding season, and on assessing the number of sousliks gained by, or lost to, kleptoparasitism.
Abstract We are currently aware of home-range sizes and mortality rates during the post-fledging dependency period (PFDP), as well as the migration routes and wintering sites of many raptors. In comparison, the period of natal dispersal is significantly understudied, including survival rates and information on the temporary settlement areas (TSA). Despite their importance, these data are unavailable for most raptor species, though they are crucial for more effective species protection and more efficient financing of nature conservation. Using satellite telemetry, we monitored twelve young saker falcons ( Falco cherrug ) from fledging through the start of dispersal, and continued monitoring until their deaths. None of them died during the PFDP, but only one survived the natal dispersal period, reached adulthood and joined the breeding population. Their PFDP lasted 47 days (median, hereinafter), and they occupied home ranges of 81 and 23 km², calculated using the 100% and 80% minimum convex polygon (MCP) methods, respectively. Monitored individuals exhibited two distinct dispersal movement/behaviour patterns: seven individuals dispersed over long (>500 km) distances, and five others over short (<100 km) distances from their natal areas. During these movements, ten individuals established 21 TSAs. These were occupied for 28 days and covered 981 and 278 km², according to the 100% and 80% MCP, respectively. The finding that only one individual survived to adulthood contrasts with the increasing population trend in Slovakia and may be a consequence of the survival impacts of tagging. However, at least half of all documented mortality was attributable to human-induced causes, including at least one-third of deaths being caused by overhead power lines. This highlights the need to eliminate or at least try to reduce all types of anthropogenic mortality, such as electrocution, hunting, and/or poisoning, as much as possible immediately, if we want to reverse negative population trends in many birds of prey and to preserve them in the long term.
Abstract We report the discovery of a nest of Montagu’s harrier ( Circus pygargus ) in northwestern Italy containing three chicks: one normally coloured with white down and two dark morph individuals with grey down. The nest was discovered during wheat harvesting and, because it was left unprotected, the chicks were collected and transferred to a wildlife rehabilitation centre. During captivity, the two grey chicks developed an almost entirely black juvenile plumage. Dark morph individuals are relatively common in Spain but are very rare in other European countries. To our knowledge, dark-morph downy chicks of Montagu’s harrier have been very rarely described and illustrated.
