Article

From sport hunting to breeding success: Patterns of lead ammunition ingestion and its effects on an endangered raptor

Authors:
  • Harmusch, Asociación de Estudio y Conservación de Fauna
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Abstract

Lead is highly toxic for wildlife, with pernicious consequences especially in long-lived predators. The causes of lead ammunition ingestion in Bonelli's eagle (Aquila fasciata) and its effects on breeding success were studied in one of the most important populations of this endangered species in Europe. Regurgitated pellets belonging to different pairs from 2004 to 2014 were analyzed, both in the breeding (1363 pellets from 12 territories) and non-breeding (172 pellets from 9 territories) seasons. From these territories, 57 molted feathers to study lead contamination were analyzed, and breeding success was monitored for 41 breeding attempts. The occurrence of lead shots in pellets was detected using X-ray photographs. Pellets were also used to describe eagle diet. Lead shots in pellets were present in 83.3% of the territories. The frequency of occurrence of lead shots in pellets (2.81% in spring and 1.31% in autumn) was primarily related to the consumption of red-legged partridge in the breeding season (when partridges are hunted from blinds using calling lures), and secondarily to rabbit consumption in the non-breeding season (coinciding with the main hunting season). Thus, our results indicate that injured small-game were the main source of lead contamination in the Bonelli's eagle. For the first time for a raptor species, a positive relationship between the frequency of occurrence of lead shots in pellets and lead concentration in eagles' feathers has been documented. Lead concentration in feathers (mean±SD: 816±426μgkg(-1), with no sex-related differences) was high for a species that rarely eats carrion or aquatic birds (the main prey-related lead source for raptors). This had negative effects on breeding success, which could jeopardize Bonelli's eagles in other European populations that are sustained by juvenile dispersal from the study population. Our work shows that some game modalities pose a potential threat to endangered raptors.

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... Poisoning by lead (Pb) is an increasing concern for the conservation of raptors due to negative effects on breeding success (Gil-Sánchez et al. 2018), or direct mortality effects (Mateo et al. 2001, Pain et al. 2019. The most relevant source of lead poisoning in raptors comes from hunting ammunition (García-Fernández 2014). ...
... Thus, raptors with scavenging habits that winter in wetlands may be highly likely to ingest lead shot present in unrecovered carcasses (Nadjafzadeh et al. 2013). Lead ingestion and poisoning have been documented in several raptor species in Spain (Mateo et al. 1997, 1999, García-Fernández et al. 2005, Gangoso et al. 2009, Pain et al. 2019, Gil-Sánchez et al. 2018. Regurgitated pellets from Spanish Imperial Eagles Aquila adalberti, Red Kites Milvus milvus and Western Marsh Harriers Circus aeruginosus, which frequently feed on bird carcasses in wetlands during winter, contained a higher presence of lead shot in pellets during the hunting season than outside it (Mateo et al. 1999(Mateo et al. , 2001(Mateo et al. , 2007. ...
... The presence of lead from ammunition was determined following the process described in Gil-Sánchez et al. (2018) for all pellets (n = 26) and a subsample of prey remains (n = 10). We used X-ray photographs obtained by a mobile veterinary radiology unit 'ISOMEDIC (model PX300 HF)' registered with the code 03/IRX/ 1205. ...
Article
Capsule: Diet analysis revealed high lead exposure for Greater Spotted Eagles Clanga clanga wintering in southeast Spain. Aims: To describe the diet composition of the endangered Greater Spotted Eagle in a wintering area located in southeast Spain, and determine lead ammunition exposure through analysis of regurgitated pellets and prey remains. Methods: Between 2008 and 2018, a total of 26 pellets, 29 prey remains and 10 direct predation observations were collected in El Hondo Natural Park, Spain. All the pellets and 10 prey remains were analysed with X-ray in order to detect metal from ammunition. Results: Greater Spotted Eagles fed mainly on birds, with 18 different species accounting for 73.1% of prey items and 66.1% of biomass consumed. The most frequent species identified were Common Moorhen Gallinula chloropus (23.1%), rats Rattus spp. (15.4%) and Common Teal Anas crecca (8.9%). Ammunition was detected in 42.3% of regurgitated pellets and in 40.0% of prey remains analysed. Of those containing ammunition, lead shot was found in 63.9% of pellets and 25.0% of prey remains. Conclusion: High lead shot presence in pellets and prey remains of wintering Greater Spotted Eagles in southeast Spain warns of a high risk of lead poisoning. Factors such as feeding behaviour, the large space-time overlap between the raptor presence and the waterbird hunting season and non-compliance with the ban on the use of lead ammunition are likely contributing to high lead exposure.
... Lead binds to calcium, settling in the bones of eagles over time (Grainger, 2012). Lead accumulated within the bones remains stable for long periods of time, but during egg formation may remobilize into the bloodstream, accumulating in eggshells, and in newborn eaglets (Burger, 1994;Gangoso et al., 2009;Vallverdú-Coll et al., 2015;Bruggeman et al., 2018;Gil-Sànchez et al., 2018). Therefore, we assume that eagles transfer their lead toxicity to their offspring. ...
... They show no clinical symptoms (Golden et al., 2016), but suffer physiological damage and have their appetite reduced by a factor w. Their scavenging rate is wδ 1 ; where 0 < w < 1, and their fertility in the model is reduced (Redig et al., 2007b;Grainger, 2012) to vr; where 0 < v < 1. Their offspring are born into the class of subclinical lead toxicity due to maternal transmission of lead (Burger, 1994;Vallverdú-Coll et al., 2015;Bruggeman et al., 2018;Gil-Sànchez et al., 2018). Inflow to the class of subclinical lead toxicity comes both from lead-free eagles, at rate ω 1 , and from eagles leaving treatment, at rate ρ. ...
... Chronic lead toxicity damages reproductive organs (Redig et al., 2007a;Fallon et al., 2017), but the reduction in fertility has not been quantified. Gil-Sànchez et al. (2018) estimated the fertility reduction factor among Bonelli eagles with subclinical lead toxicity at v ¼ 0:7. The treatment rate η of eagles with clinical lead toxicity depends on human intervention. ...
Article
Ingestion of lead-based ammunition is one of the leading causes of the mortality of bald eagles. Their primary source is unretrieved carrion contaminated with lead from hunters’ ammunition. Lead toxicity can have serious clinical consequences, including reduced fertility and consumption. A model with ordinary differential equations describes the dynamics of available contaminated carrion and the progression of eagles through stages of lead poisoning. Nonnegative solutions exist and equilibrium points are stable for certain parameter ranges. Sensitivity analysis shows that the bald eagle population in the Great Lakes region is primarily dependent on the rate of entry of contaminated carrion in the environment, more so than on retrieval or on the rate of treatment of eagles. Estimates of financial costs of each of these three measures show that the most effective measure is to find a substitute for lead cartridges.
... The examination of regurgitated pellets is a noninvasive method that allows the determination of a population's exposure to lead (Pain et al. 2009). Obligate scavengers (e.g., vultures) and opportunistic scavengers (e.g., eagles [Haliaeetus sp.]) are especially vulnerable to lead exposure (Gil-Sanchéz et al. 2018). In this study, contamination of collected pellets was twice as high during the hunting season compared with the rest of the year, indicating a higher risk of lead exposure for White-tailed Sea-Eagles during the hunting season. ...
... Similarly, in Sweden, 9% of White-tailed Sea-Eagle pellets were contaminated in the winter and 0.7% in the summer (Helander 1983). An analysis of the pellets from the Bonelli's Eagle (Aquila fasciata) in Spain showed a lead shot contamination of 2.8% in spring vs. 1.3% in autumn (Gil-Sanchéz et al. 2018). The contamination rate during the non-hunting season in this study was relatively high compared to the published studies, a phenomenon that might result from the fact that the most frequently identified prey species, wild boar, is hunted year round in Germany. ...
... Pellets often contained more than one species of bird or mammal remains, therefore percentages add up to more than 100%. the presence of lead shot in the regurgitated pellets of the Bonelli's Eagle was documented in Spain (Gil-Sanchéz et al. 2018). Another study conducted in Spain demonstrated that the identified waterfowl in the contaminated pellets from the Greater Spotted Eagle were the source of the detected lead shot because the raptors feed mainly on waterfowl while residing in their wintering area in southeastern Spain, which correlates in time with the main waterfowl hunting season (Pérez-Garía et al. 2020). ...
Article
Full-text available
Anthropogenic lead intoxication is the most frequent cause of death of White-tailed Sea-Eagles (Haliaeetus albicilla) in Germany. Most lead fragments are ingested by eagles feeding on carcasses and viscera of game animals shot with lead-based ammunition left in the wild by hunters. We investigated how many regurgitated pellets contained metal fragments and hypothesized a correlation between the presence of metal fragments and (1) the hunting season, (2) the ban of lead in rifle ammunition, and (3) the frequency of specific prey animals in the pellets. We collected 273 regurgitated pellets, radiographed them for metal fragments, and analyzed the prey composition. The metal elements were identified using micro x-ray fluorescence. Metal particles were found in 9.2% of pellets; 24 fragments consisted of lead and one fragment was mostly copper. A higher proportion (14.3%) of contaminated pellets was detected during the hunting season from September through February. During the non-hunting season from March through August, 7.6% of the regurgitated pellets were contaminated. Furthermore, there was a significant positive correlation between the presence of mammalian remains in the pellets and metal contamination (general linear model, z = 2.16, P = 0.03). Our results indicate a correlation between the increased activity of hunters in winter and the occurrence of metal in regurgitated pellets of White-tailed Sea-Eagles.
... Indirect mortality is when reports attribute the death to another proximate cause but lead poisoning was the ultimate cause because it sublethally weakened the bird, increasing its susceptibility to death from the direct, proximate cause of death [16]. Some field studies suggest such sublethal effects are present [17][18][19][20][21], while others support that birds with sublethal lead levels are not predisposed to other causes of mortality [22]. Nonetheless, one or both types of mortality can be incorporated into the first step of our approach. ...
... Developing a method to assess effects on raptor reproduction was more challenging because reproductive effects from lead ingestion are not always observed in the laboratory [47], and percentages of populations consuming lead shot and bullets in Europe at sublethal levels is unknown. We found one estimate in the literature of the possible reduction in reproduction of a raptor at sublethal levels, which was a 75% reduction in chicks fledged in the field (from an average of 2 to 0.5) from the Gil-Sánchez et al. [21] Bonelli eagle field study. That reduction percentage is uncertain, because (1) it was a correlative rather than controlled study, and (2) soil may have been a source of lead [36]. ...
Article
Full-text available
Current estimates of terrestrial bird losses across Europe from ingestion of lead ammunition are based on uncertain or generic assumptions. A method is needed to develop defensible European-specific estimates compatible with available data that does not require long-term field studies. We propose a 2-step method using carcass data and population models. The method estimates percentage of deaths diagnosed as directly caused by lead poisoning as a lower bound and, as an upper bound, the percentage of possible deaths from sublethal lead poisoning that weakens birds, making them susceptible to death by other causes. We use these estimates to modify known population-level annual mortality. Our method also allows for potential reductions in reproduction from lead shot ingestion because reductions in survival and reproduction are entered into population models of species with life histories representative of the most groups of susceptible species. The models estimate the sustainability and potential population decreases from lead poisoning in Europe. Using the best available data, we demonstrate the method on two taxonomic groups of birds: gallinaceous birds and diurnal raptors. The direction of the population trends affects the estimate, and we incorporated such trends into the method. Our midpoint estimates of the reduction in population size of the European gallinaceous bird (< 2%) group and raptor group (2.9–7.7%) depend on the species life history, maximum growth rate, population trend, and if reproduction is assumed to be reduced. Our estimates can be refined as more information becomes available in countries with data gaps. We advocate use of this method to improve upon or supplement approaches currently being used. As we demonstrate, the method also can be applied to individual species of concern if enough data across countries are available.
... Vultures dissolve and absorb lead soon after ingestion due to their low stomach pH, often resulting in acute death (García-Fernández et al. 2005, Fisher et al. 2006. Sublethal or chronic exposure (prolonged exposure at lower concentrations) is also of concern because it can make birds less fit and predispose them to other causes of death (Mateo et al. 2003, Pain et al. 2007, Berny et al. 2015 or may affect reproductive success (Buerger et al. 1986, Gil-Sánchez et al. 2018, behavior (Scheuhammer 1987), or physiology (Burger 1995, Fair and Ricklefs 2002, Naidoo et al. 2012. ...
... For example, the accumulation of lead in bones from lead ammunition affects the degree of bone mineralization in Egyptian Vultures, which could mean an increase in bone fragility . The accumulation of lead over time is an additional threat to the species because it can affect the fitness of a population, including reproduction (Gil-Sánchez et al. 2018), thus affecting the long-term survival of long-lived species. The effects of the cumulative exposure to lead on this population are difficult to assess with the low sample sizes in this study. ...
Article
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Lead poisoning is an important threat to some raptor species, and the primary source of lead is through the ingestion of carcasses that have been shot with lead, which makes scavengers such as vultures particularly vulnerable. We examined the concentrations of lead in blood and bone tissue samples collected throughout the range of the Bearded Vulture (Gypaetus barbatus) in southern Africa. This population is regionally critically endangered and it is not known to what extent lead poisoning may be a threat. Blood lead levels (0.62 ± 0.81 μg dL⁻¹) from six live birds tested in 2017 indicated background levels of exposure to lead. Similarly, five live birds tested in 2009 using a less sensitive method all had blood lead levels <3 μg dL⁻¹. Bone lead levels (11.79 ± 8.34 μg g⁻¹) from eight birds that had died indicated lead exposure and accumulation over time, suggesting that lead may have contributed to their deaths. These levels of lead may be detrimental to the survival and fecundity of this small and declining population. Recommendations to address this threat include banning hunting and culling with lead ammunition, which is the most likely source of this pollutant. Such actions may reduce the population's susceptibility to other threats, which may be compounded by high lead levels, and help ensure the success of planned reintroduction programs.
... The overall concentrations of As (0.09 ± 0.12 μg g −1 ) and Pb (0.17 ± 0.18 μg g −1 ) were relatively low, compared for instance with a study reporting contamination in passerines close to mining areas in Mexico (As: 2.12 μg g −1 ; Pb: 36.28 μg g −1 , Monzalvo-Santos et al., 2016). Concentrations of Pb were also much lower than those reported in Bonelli's eagles in Spain (0.82 ± 0.44 μg g-1), where the ingestions of lead particles from injured small game prey seem to be pervasive (Gil-Sánchez et al., 2018). This suggests that a similar problem does not occur in southern Portugal, probably due to the higher consumption of domestic pigeons and other non-game species by Bonelli's eagles in Portugal compared with those in Spain (Gil-Sánchez et al., 2018;Palma et al., 2006). ...
... Concentrations of Pb were also much lower than those reported in Bonelli's eagles in Spain (0.82 ± 0.44 μg g-1), where the ingestions of lead particles from injured small game prey seem to be pervasive (Gil-Sánchez et al., 2018). This suggests that a similar problem does not occur in southern Portugal, probably due to the higher consumption of domestic pigeons and other non-game species by Bonelli's eagles in Portugal compared with those in Spain (Gil-Sánchez et al., 2018;Palma et al., 2006). Little is known about the toxicity threshold of As concentrations in feathers, whereas for Pb a threshold value of 4.0 μg g −1 in feathers has been suggested (Burger, 1993). ...
Article
Understanding the levels and drivers of contamination in top predators is important for their conservation and eventual use as sentinels in environmental monitoring. Therefore, metals and trace elements were analyzed in feathers of Bonelli’s eagles (Aquila fasciata) from southern Portugal in 2007-2013, where they are believed to be exposed to a wide range of contamination sources such as agricultural land uses, urban areas, active and abandoned mines and a coal-fired power plant. We focused on concentrations of aluminum (Al), arsenic (As), copper (Cu), chromium (Cr), mercury (Hg), lead (Pb), selenium (Se) and zinc (Zn), as these contaminants are potentially associated with those sources and are known to pose a risk for terrestrial vertebrates. Stable isotope values of nitrogen (δ15N: 15N/14N), carbon (δ13C: 13C/12C) and sulphur (δ 34S: 34S/32S) were used as dietary proxies to control for potential effects of prey composition on the contamination pattern. The spatial distribution of potential contamination sources was quantified using geographic information systems. Concentrations of Hg in the southern part of the study area were above a reported toxicity threshold for raptors, particularly in territories closer to a coal-fired power plant at Sines, showing that contamination persisted after a previous assessment conducted in the 1990s. Hg and Se levels were positively correlated with δ15N, which indicates biomagnification. Concentrations of As, Cr, Cu, Pb and Zn were generally low and unrelated to mining- or industrial activities, indicating low environmental background concentrations. Al was found at higher concentrations in the southernmost areas of Portugal, but this pattern might be related to external soil contamination on feathers. Overall, this study indicates that, among all elements studied, Hg seems to be the most important contaminant for Bonelli’s eagles in southern Portugal, likely due to the power plant emissions and biomagnification of Hg in terrestrial food webs.
... Because vultures are long-lived, they are predisposed to bioaccumulation of heavy metals such as Pb (Behmke et al., 2015). Although vultures appear quite tolerant of Pb Naidoo et al., 2017), sub-lethal effects can reduce overall fitness and reduce reproductive output of raptors (Gil-Sánchez et al., 2018;Vallverdú-Coll et al., 2016). If this is occurring in our populations then this non-lethal Pb exposure could hinder vulture populations from recovering from mass poisonings as well as threatening overall population sustainability through reduced productivity. ...
Article
Lead (Pb) toxicity caused by the ingestion of Pb ammunition fragments in carcasses and offal is a threat to scavenging birds across the globe. African vultures are in critical decline, but research on whether Pb exposure is contributing to declines is lacking. In Africa, recreational hunting represents an important economic activity; however, Pb in leftover hunted carcasses and gut piles represents a dangerous food source for vultures. It is therefore important to establish whether recreational hunting is associated with Pb exposure in African vultures. We explored this issue for the critically endangered white-backed vulture (Gyps africanus) in Botswana by examining their blood Pb levels inside and outside of the hunting season, and inside and outside of private hunting areas. From 566 birds captured and tested, 30.2% birds showed elevated Pb levels (10 to <45 μg/dl) and 2.3% showed subclinical exposure (≥45 μg/dl). Higher blood Pb levels were associated with samples taken inside of the hunting season and from within hunting areas. Additionally, there was a significant interaction between hunting season and areas, with Pb levels declining more steeply between hunting and non-hunting seasons within hunting areas than outside them. Thus, all our results were consistent with the suggestion that elevated Pb levels in this critically endangered African vulture are associated with recreational hunting. Pb is known to be highly toxic to scavenging birds and we recommend that Pb ammunition in Botswana is phased out as soon as possible to help protect this rapidly declining group of birds.
... The recent revelation of substantial lead exposure in Botswanan African white-backed vultures shows that hunting with lead ammunition could have severe repercussions for vulture populations . Vultures that ingest lead ammunition fragments leftover in carcasses can either die or exhibit severe sub-lethal affects which can hinder reproduction and reduce overall fitness, consequently decreasing chances of survival (Gil-Sánchez et al., 2018;Vallverdú-Coll et al., 2016). This is yet another threat that could result in unsustainable population losses if not addressed. ...
Article
Across Africa, many raptor species, especially vultures, are in steep decline. Botswana is regionally important for numerous raptor species including vultures, but recent population trends of raptors within this country are totally unknown. In 2015-2016 we repeated road transects for raptors across northern Botswana that were first conducted in 1991-1995. In total, we re-surveyed 20,712 km of transects. From these data we explored changes in abundance of 29 species. Fourteen species (48%) showed significant declines. Of these, 11 species declined by > 50% and three species declined by 37-50%. Non-significant declines of > 70% were shown for four species , of 30-65% for six species and of < 10% for a further two species. In contrast only three species, all large eagles-tawny eagle (Aquila rapax), brown snake eagle (Circaetus cinereus) and black-chested snake eagle (Circaetus pectoralis), showed significant but small increases of between 6 and 15%. For most species, population trends were similar both inside and outside of protected areas, with only two species showing significantly different trends. Declines of bateleur eagle (Terathopius ecaudatus) were lower inside protected areas. In contrast, brown snake eagles showed stable populations inside protected areas but large increases outside of protected areas. These re-surveys suggest extremely worrying trends for multiple raptor species in Botswana, and highlights the benefit of repeating historical surveys to understand population trends in countries that lack systematic monitoring of wildlife populations.
... This is demonstrated in the endangerment of White-backed Vultures (Gyps africanus) in Botswana (Garbett et al. 2018), California Condors, and other scavenging birds in the continental USA (Golden et al. 2016). Different species of eagles have been shown to be seriously impacted by lead ammunition ingestion across the holarctic (Nadjafzadeh et al. 2013;Ecke et al. 2017;Ishii et al. 2017;Gil-Sánchez et al. 2018;Isomursu et al. 2018). Population-level declines in waterfowl wintering in the UK have been identified (Green and Pain 2016). ...
Article
Full-text available
This review presents evidence of lead exposure and toxicity to wildlife and humans from spent shotgun and rifle ammunition and fishing weights, and the barriers and bridges to completing the transition to non-lead products. Despite the international availability of effective non-lead substitutes, and that more jurisdictions are adopting suitable policies and regulations, a broader transition to non-lead alternatives is prevented because resolution remains divided among disparate human user constituencies. Progress has occurred only where evidence is most compelling or where a responsible public authority with statutory powers has managed to change mindsets in the wider public interest. Arguments opposing lead bans are shown to lack validity. Differing national regulations impede progress, requiring analysis to achieve better regulation. Evidence that lead bans have reduced wildlife exposure should be used more to promote sustainable hunting and fishing. Evidence of the lead contribution from hunted game to human exposure should shape policy and regulation to end lead ammunition use. The Special Issue presents evidence that a transition to non-lead products is both warranted and feasible.
... However, these data around kea are anecdotal and the degree of exposure from any specific source is unknown. Worldwide, elevated lead levels in carrion-eating birds are tied to these animals eating lead-shot carrion (Gil-Sánchez et al., 2018;Hampton et al., 2018;Krone, 2018). We suggest that kea scavenging carrion shot with lead bullets is a more likely source of these elevated lead levels in kea than exploring lead-based roofing materials. ...
... Such animals would fare a greater risk to be predated. A study on the Bonnelli's eagle (Aquila fasciata) in Spain showed a high occurrence of lead shot in the eagle castings and indicated that injured small game was the main source of lead contamination in this non-scavenging raptor (Gil-Sánchez et al. 2018). Incidences of Pb poisoning in eagle owl have been reported from Spain and Korea (Kim and Oh 2012). ...
Article
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Patterns of lead and other trace metals were examined in 122 Eurasian eagle owls Bubo bubo found dead in Sweden in the period 1978–2013. Environmental lead (Pb) has decreased over recent decades from reduced anthropogenic emissions but mortality by Pb poisoning is still frequently reported for avian raptors and scavengers exposed to Pb ammunition. One objective here was to determine if Pb concentrations in a nocturnal non-scavenging raptor follow the general decline observed in other biota. Pb concentration in owl liver was significantly correlated with body weight, sex, latitude, longitude and season. Pb showed a significant decreasing trend towards north and west. Starved birds had significantly higher concentrations. Total Pb concentrations in liver averaged 0.179 μg g⁻¹ dry weight (median 0.103) and decreased by 5.6% per year 1978–2013, or 5.3% after adjustment for confounding factors, similar to trends in other species. Among 14 other trace elements only antimony and arsenic showed decreasing trends. Lead isotope ratios ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb increased from 1.138 and 2.408 in 1978–1985 to 1.170 and 2.435 in 2010–2013, respectively, demonstrating that the decreasing Pb concentration in eagle owl is related to the phase-out of leaded gasoline in Europe, where Pb additives had much lower isotope ratios than natural lead in Swedish soils. Only one incidence of suspected Pb poisoning (40.7 μg g⁻¹ in liver) was observed indicating that poisoning from ingestion of metallic lead is rare (< 1%) in eagle owl in Sweden, in contrast to what has been reported for eagles.
... Globally, Pb is a major threat to scavenging raptors that feed on hunter-killed offal, and unretrieved game and managed pest carcasses that have been shot with Pb-based ammunition (Haig et al. 2014, Ecke 2017, Garbett et al. 2018, Gil-S anchez et al. 2018. As one of the largest predatory and scavenging species of raptors, Golden Eagles (Aquila chrysaetos) are at risk of substantial Pb exposure from scavenging throughout their global range (Austria, Kenntner et al. 2007; Canada, Wayland and Bollinger 1999;Germany, Kenntner et al. 2007; Italy, Squadrone et al. 2018;Japan, Ishii et al. 2017;Sweden, Ecke 2017;Switzerland, Jenni et al. 2015;USA, Langner et al. 2015). ...
Article
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Supplementary food resources (e.g., subsidies) associated with agriculture can benefit wildlife species, increasing predictability and availability of food. Avian scavengers including raptors often utilize subsidies associated with both recreational hunting and pest shooting on agricultural lands. However, these subsidies can contain lead (Pb) fragments if they are culled with Pb‐based ammunition, potentially leading to Pb poisoning and physiological impairment in wildlife. Nesting Golden Eagles (Aquila chrysaetos) commonly forage in agricultural lands during the breeding season, and therefore, both adults and their nestlings are susceptible to Pb exposure from scavenging shot wildlife. We assessed drivers of Pb exposure in 258 nestling Golden Eagles (401 total blood samples), along with physiological and growth responses, in agricultural lands across four western states in the United States. We also evaluated the birds’ Pb stable isotope signatures to inform exposure sources. Twenty‐six percent of Golden Eagle nestlings contained Pb concentrations associated with subclinical poisoning for sensitive species (0.03–0.2 μg/g ww), 4% had Pb concentrations that exceeded subclinical poisoning benchmarks (0.2–0.5 μg/g ww), and <1% exceeded either concentrations associated with clinical poisoning (0.5–1.0 μg/g ww) and or those deemed to cause severe clinical poisoning (>1.0 μg/g ww). Lead concentrations were highest in nestlings with close proximity to fields that potentially provided subsidies and declined exponentially as distance to subsidies increased. However, close proximity to agriculture, and presumably subsidies, positively influenced nestling growth rates. Across the range of Pb exposure, nestlings experienced a 67% reduction in delta‐aminolevulinic acid dehydratase (δ‐ALAD) activity, suggesting nestlings may have been anemic or experiencing cellular damage. Isotopic ratios of 206Pb/207Pb increased non‐linearly with increasing blood Pb in Golden Eagle nestlings, and 45% of the birds were consistent with those of ammunition. However, above 0.10 μg/g ww, the proportion associated with ammunition increased to 89% of the nestlings. An improved understanding of how these positive (growth) and negative (physiology) effects associated with proximity to subsidies interact would be beneficial to managers when considering management scenarios and potentially evaluating any measures taken to reduce Pb exposure across the landscape.
... They suggested that the most likely source of this poisoning was from spent lead ammunition from hunting. Elevated lead levels can negatively affect breeding performance in raptors (Gil-Sánchez et al. 2018), including effects of adult sub-lethal exposure causing chick death (Pikula et al. 2013). Thus, high levels of lead in the local Whitebacked Vulture population could partially explain the reduced breeding success observed in this population. ...
Article
African White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years.
... For example, Pb intoxication has been identified as an important mortality factor for vultures and facultative scavengers across Europe (Berny et al., 2015;Helander et al., 2009;Krone et al., 2009). However, foraging on gunshot-injured but still living mammals and waterfowl can also result in significant exposure risk for non-scavengers (Gil-Sánchez et al., 2018;Mateo et al., 1999). ...
Article
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Biomonitoring in raptors can be used to study long-term and large-scale changes in environmental pollution. In Europe, such monitoring is needed to assess environmental risk and outcomes of chemicals regulation, which is harmonised across the European Union. To be effective, the most appropriate sentinels need to be monitored. Our aim was to identify which European raptor species are the likely most appropriate biomonitors when pollutant quantification is based on analysing tissues. Our current study was restricted to terrestrial exposure pathways and considered four priority pollutant groups: toxic metals (lead and mercury), anticoagulant rodenticides, pesticides and medicinal products. We evaluated information on the distribution and key ecological traits (food web, foraging trait, diet, preferred habitat, and migratory behaviour) of European raptors to identify the most appropriate sentinel species. Common buzzard (Buteo buteo) and/or tawny owl (Strix aluco) proved the most suitable candidates for many of the pollutants considered. Moreover, they are abundant in Europe, enhancing the likelihood that samples can be collected. However, other species may be better sentinels for certain pollutants, such as the golden eagle (Aquila chrysaetos) for lead, the northern goshawk (Accipiter gentilis) for mercury across areas including Northern Europe, and vultures (where they occur in Europe) are likely best suited for monitoring non-steroidal anti-inflammatory drugs (NSAIDs). Overall, however, we argue the selection of candidate species for widescale monitoring of a range of pollutants can be reduced to very few raptor species. We recommend that the common buzzard and tawny owl should be the initial focus of any pan-European raptor monitoring. The lack of previous widespread monitoring using these species suggests that their utility as sentinels for environmnetal pollution has not been widely recognised. Finally, although the current study focussed on Europe, our trait-based approach for identifying raptor biomonitors can be applied to other continents and contaminants.
... Therefore, in animals living in natural ecosystems, the level of some heavy metals is often higher than in farmed animals (22,30,32,37). In game animals, secondary lead contamination may also occur through bullets and the accidental consumption of lead shot in the environment (9,13,29). The accumulation of heavy metals, including toxic ones, and the deficiency of some bioelements may have a significant impact on animal health including game animals and the quality of the obtained carcasses. ...
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Introduction Differing conditions in captive breeding and in the wild have impact on the mineral profile of the pheasant carcass and its heavy metal contents. This may be an indicator of environmental contamination. The study evaluated the nutritional composition and selected macro- and trace element contents (heavy metals in particular) in usable sections of pheasant breast and thigh muscles originating from captive breeding and wild birds. Material and Methods The tests were performed on the breast and thigh muscles of 20 wild and 20 farm bred birds from around Lublin, Poland, with equal sex representation. The nutrient and lead, cadmium, chromium, and nickel contents were determined using inductively-coupled plasma atomic emission spectroscopy. Results The farmed pheasants had a higher proportion of breast muscle. The thigh muscles of all birds had a higher fat content than the breast muscles (5.1 g vs . 3.4 g per kg of natural weight). The macroelement level depended on the muscle type and bird origin. The trace element content also did and gender dependence was also evident. The wild birds contained more cadmium in the breast muscles and lead in both muscles than the farm-raised ones. Conclusion The high quality and usefulness of wild and farmed pheasant meat is confirmed. It has advantageous macro- and trace element contents and permissible heavy metal contents except for lead in wild birds. The heavy metal level can be a bioindicator of their environmental occurrence. In wild birds, the lead level may also reflect birdshot remnants.
... Less is known about the potential reprotoxic effects of lead in raptors (Table 2). Although Gil-Sánchez et al. (2018) did observe an apparent direct negative relationship between high lead concentrations and the number of fledglings per breeding attempt in Bonnelli's eagle (Aquila fasciata), they could not suggest a likely mechanism of action. Pain et al. (1999) showed that lead did not affect shell thicknesses and suggested that any pathway by which lead might affect reproductive success would be through direct effects on the parents that resulted in impaired incubation or nestling care. ...
Article
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Lead contamination is a widely recognised conservation problem for raptors worldwide. There are a number of studies in individual raptor species but those data have not been systematically evaluated to understand raptor-wide lead exposure and effects at a pan-European scale. To critically assess the extent of this problem, we performed a systematic review compiling all published data on lead in raptors (1983–2019) and, through a meta-analysis, determined if there was evidence for differences in exposure across feeding traits, geographical regions, between hunting and non-hunting periods, and changes over time. We also reviewed the impact of lead on raptors and the likely main source of exposure. We examined 114 studies that were unevenly distributed in terms of time of publication and the countries in which studies were performed. Peer-reviewed articles reported data for 39 raptor species but very few species were widely monitored across Europe. Obligate (vultures) and facultative scavengers (golden eagle, common buzzard and white-tailed sea eagle) accumulated the highest lead concentrations in tissues and generally were the species most at risk of lead poisoning. We found no evidence of a spatial or decadal trend in lead residues, but we demonstrated that high lead blood levels relate to hunting season. Exposure at levels associated with both subclinical and lethal effects is common and lead from rifle bullets and shot is often the likely source of exposure. Overall, our review illustrates the high incidence and ubiquity of lead contamination in raptors in Europe. However, we did not find studies that related exposure to quantitative impacts on European raptor populations nor detailed studies on the impact of mitigation measures. Such information is urgently needed and requires a more harmonised approach to quantifying lead contamination and effects in raptors across Europe.
... Elliott et al., 1992;Kramer and Redig, 1997;Clark and Scheuhammer, 2003;Church et al., 2006;Craighead and Bedrosian, 2009;Johnson et al., 2013;Franson and Russel, 2014;Katzner et al., 2018;Behmke et al., 2015;Slabe, 2019;Simon et al., 2020), and from Europe (e.g. Krone et al., 2002Krone et al., , 2006Krone et al., , 2009aKrone et al., , 2009bKenntner et al., 2004Kenntner et al., , 2007Helander et al., 2009;Berny et al., 2015;Jenni et al., 2015;Madry et al., 2015;Ecke et al., 2017;Kitowski et al., 2017;Gil-Sánchez et al., 2018;Isomursu et al., 2018;Bassi et al., 2021;Fuchs et al., 2021) as well as from other continents (e.g. Ueta and McGrady, 2000;Krone et al., 2004;Saito, 2009;Garbett et al., 2017;Ishii et al., 2017;Lohr et al., 2020;Pay, 2020). ...
Article
Exposure to lead (Pb) from ammunition in scavenging and raptorial birds has achieved worldwide recognition based on incidences of lethal poisoning, but exposure implies also sublethal levels with potential harmful effects. Background and elevated Pb levels in liver from 116 golden eagles (GE, Aquila chrysaetos) and 200 white-tailed sea eagles (WTSE, Haliaeetus albicilla) from Sweden 2003–2011 are here examined, with supporting data from a previous WTSE report and eagle owl (EO, Bubu bubo) report. GE and WTSE display seasonal patterns, with no Pb level exceeding a generally accepted threshold for subclinical effects during summer but strongly elevated levels from October. Fledged juveniles show significantly lower levels than all other age classes, but reach levels found in older birds in autumn after the start of hunting seasons. Pb levels in EO (non-scavenger) show no seasonal changes and indicate no influence from ammunition, and are close to levels observed in juvenile eagles before October. In all, 15% WTSE and 7% GE were lethally poisoned. In areas with high-exposure to hunting ammunition, 24% of WTSE showed lethal Pb levels, compared to 7% in both eagle species from low-exposure areas. Lethal poisoning of WTSE remained as frequent after (15%) as before (13%) a partial ban on use of Pb-based shotgun ammunition over shallow waters (2002). Pb levels increased significantly in WTSE 1981–2011, in contrast to other biota from the same period. A significant decrease of Pb in WTSE liver occurred below a threshold at 0.25 μg/g (dry weight), exceeded by 81% of the birds. Trend patterns in Pb isotope ratios lend further support to this estimated cut-off level for environmental background concentrations. Pb from spent ammunition affects a range of scavenging and predatory species. A shift to Pb-free ammunition to save wildlife from unnecessary harm is an important environmental and ethical issue.
... This should reduce levels of lead, mercury, and other typical contaminants in the environmenttoxic agents known to negatively affect raptors (Franson and Russell, 2014;Redig and Arent, 2008). Significant lockdown reductions in groundwater pollutants, such as reported from India for selenium (42%) and lead (50%) (Selvam et al., 2020), may also be beneficial to raptors (Gil-Sánchez et al., 2018;Wiemeyer and Hoffman, 1996). On the other hand, large quantities of disinfectants were sprayed in some urban public areas in an attempt to contain the spread COVID-19 in China, South Korea, and Italy (Palmer et al., 2020;Service, 2020). ...
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Research is underway around the world to examine how a wide range of animal species have responded to reduced levels of human activity during the COVID-19 pandemic. In this perspective article, we argue that raptors are particularly well-suited for investigating potential ‘anthropause’ effects, and that the resulting insights will provide much-needed impetus for global conservation efforts. Lockdowns likely alter many of the extrinsic factors that normally limit raptor populations. These environmental changes are in turn expected to influence – mediated by behavioral and physiological responses – the intrinsic (demographic) factors that ultimately determine raptor population levels and distributions. Using this framework, we identify a range of research opportunities and conservation challenges that have arisen during the pandemic. The COVID-19 anthropause allows raptor researchers to address fundamental and applied research objectives in a large-scale, quasi-experimental, well-replicated manner. Importantly, it will be possible to separate the effects of human disturbance and anthropogenic landscape modifications. We explain how high-quality datasets, accumulated for a diverse range of raptor species before, during, and after COVID-19 lockdowns, can be leveraged for powerful comparative analyses that attempt to identify drivers of particular response types. To facilitate and coordinate global collaboration, we are hereby launching the ‘Global Anthropause Raptor Research Network’ (GARRN). We invite the international raptor research community to join this inclusive and diverse group, to tackle ambitious analyses across geographic regions, ecosystems, species, and gradients of lockdown perturbation. Under the most tragic of circumstances, the COVID-19 anthropause has afforded an invaluable opportunity to significantly boost global raptor conservation.
... Birds are often used as bioindicators of pollution within an ecosystem (e.g., [83,84]), particularly heavy metal pollution [83]. Much of the research to date on the physiological consequences of heavy metal pollution in birds have been studied in nonsongbirds, including waterfowl, raptors, and seabirds (e.g., [85][86][87][88][89]), which are especially likely to consume food containing bioaccumulated heavy metals. Nonetheless, once studies showed changes in birdsong between non-polluted and heavy metal-polluted sites (e.g., [90][91][92]), researchers began examining whether the underlying neural architecture in songbirds was also affected. ...
Chapter
Songbirds are one of a few examples of animals (including humans) that require hearing a model of species-typical vocalizations in order to accurately learn to sing themselves. To support this developmental process, songbirds have dedicated neural regions and pathways, and associated neurotransmitters, for learning song, in addition to those for production and perception. However, changing and disappearing habitats may introduce elements that interfere with the ability of offspring to learn song from adults and compromise the underlying neural architecture that supports song learning. This chapter will review the ontogeny of song learning and the related neural structures and describe results from both laboratory and field experiments examining effects of anthropogenic changes such as increased noise, stress from noise and food restriction, and environmental contaminants. We also consider how songbirds may be able to adapt to some changes but not others. We suggest these constraints can inform habitat conservation in ways that allow songbirds to develop behaviours related to vocal communication that are critical for mate selection and, ultimately, species survival.
... Passive monitoring of contaminants can be done using samples from dead raptors (e.g., internal tissues, gastric contents, feathers, and preen oil/gland), while active monitoring can be done with samples from trapped live birds and nests (e.g., blood, plasma/serum, deserted or addled eggs, regurgitated pellets or prey remains, preen oil, and feathers, Espín et al., 2021). Studies have highlighted the usefulness of raptors as biomonitors of heavy metals (which impair the immune systems of Black Kites (Milvus migrans; Blanco et al., 2004), organochlorines including dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyl (PCB), [which affect reproduction in White-tailed Eagles (Haliaeetus albicilla; Korsman et al., 2012)], and lead intoxication associated with hunting [which reduces the breeding success of Bonelli's Eagles (Aquila fasciata; Gil-Sánchez et al., 2018)]. There are currently plans underway for pan-European biomonitoring using raptors (Dulsat-Masvidal et al., 2021). ...
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African vulture populations are rapidly declining, yet funding and other resources available for their conservation are limited. Improving our understanding of which African vulture species could best serve as an umbrella species for the entire suite of African vultures could help conservationists save time, money, and resources by focusing their efforts on a single vulture species. Furthermore, improving our understanding of the suitability of African vultures as biomonitors for detecting environmental toxins could help conservation authorities to detect changes in ecosystem health. We used a systematic approach based on criteria selected a priori to objectively evaluate the potential of each of the 10 resident African vulture species as (i) an umbrella species for all of the African vulture species, and (ii) an avian biomonitor. For each criterion, we scored the respective African vulture species and summed the scores to determine which species was best suited as an umbrella species and as an avian biomonitor. Our results showed that, overall, certain aspects of vulture ecology (large population sizes, large body sizes, long lifespans, and their ability to be monitored over numerous seasons) support their suitability as biomonitors, while other ecological traits, including their diets and the public’s perceptions of vultures, could diminish their suitability. The White-backed Vulture (Gyps africanus) was the best fit of the 10 vulture species in our assessment as both an avian biomonitor and an umbrella species for all African vulture species. Meanwhile, significant knowledge gaps for other species inhibit their utility as biomonitors. Due to their large home-range sizes, African vultures may only be useful as biomonitors at a regional scale. However, there could be value in using the White-backed Vulture as an umbrella species, as an aid to conserve the entire suite of African vulture species.
... Game species encountered in the golden eagle diet collection and behavioral datasets include the wild boar (Sus scrofa, whose offal is usually discarded in situ), hares, Turdus thrushes, ducks and woodpigeons, that are legally hunted in Greece during the winter months. Especially in winter and by immature individuals, the consumption of such items might be a possible pathway of lead ingestion as has been found elsewhere for this and other eagle species [107][108][109][110]. Lead levels have only been investigated incidentally in Greek raptors [111] and relevant studies incorporating tissues of dead birds, feathers and whole blood of handled specimens are required (preliminary findings in four of our territorial eagles have found small but detectable levels, Azmanis and Sidiropoulos, unpublished data). ...
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Golden Eagles are resident in Greece and known to feed mainly on tortoises when breeding. However, information on alternative prey is scarce, especially during the tortoise brumation, that roughly coincides with the eagles’ non-breeding season. We analyzed 827 prey items collected from 12 territories over five territory years and 84 records of eagles hunting or feeding behavior. Tortoises dominated the breeding season diet (71% of prey categories on average) and over half of all hunting/feeding observations. While no spatial structure was evident, habitat variables such as forest canopy cover were important associates in golden eagle diet seasonally. A significant seasonal pattern emerged in diet diversity, using a subset of six territories with at least 10 samples per season. Eagles shifted from a narrow, reptile- based breeding season diet dominated by tortoises to a broader non-breeding season diet, that included more carrion, mammals and birds. Breeding season specialization on ectothermic prey is a trait usually associated with migratory raptors in the Western Palearctic. The observed dietary diversity expansion accompanied by residency in the absence of ectothermic prey, highlights the adaptability of the golden eagle, a generalist predator. Tortoise populations in Greece are of conservation concern and land use changes as well as climate change, such as development and land abandonment may increase the prevalence of catastrophic megafires, exacerbating the threats to the golden eagle’s main prey when breeding. We discuss this and other diet related conservation implications for the species in northern Greece.
... For instance, food chain linkage has been found in North America between the earthworm-eating North American Woodcock Scolopax minor and lead gunshot, and it is possible that Woodcock S. rusticolor in Europe are similarly exposed to lead in their diet (Scheuhammer et al. 1998(Scheuhammer et al. , 2003Hiller and Barclay 2011;Lead Ammunition Group 2015). Avian scavengers, notably eagles, buzzards, kites and vultures are poisoned having consumed meat from animals with elevated tissue lead levels, or containing either lead gunshot or fragments of lead rifle bullets (Scheuhammer and Norris 1995;Pain et al. 1997;Krone et al. 2009;Gangoso et al. 2009;Hunt 2012;Berny et al. 2015;Ecke et al. 2017;Gil-Sánchez et al. 2017). ...
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Much evidence demonstrates the adverse effects of lead ammunition on wildlife, their habitats and human health, and confirms that the use of such ammunition has no place within sustainable hunting. We identify the provisions that define sustainable hunting according to European law and international treaties, together with their guidance documents. We accept the substantial evidence for lead’s actual and potential effects on wildlife, habitats and health as persuasive and assess how these effects relate to stated provisions for sustainability and hunting. We evaluate how continued use of lead ammunition negatively affects international efforts to halt loss of biodiversity, sustain wildlife populations and conserve their habitats. We highlight the indiscriminate and avoidable health and welfare impacts for large numbers of exposed wild animals as ethically unsustainable. In societal terms, continued use of lead ammunition undermines public perceptions of hunting. Given the existence of acceptable, non-toxic alternatives for lead ammunition, we conclude that hunting with lead ammunition cannot be justified under established principles of public/international policy and is not sustainable. Changing from lead ammunition to non-toxic alternatives will bring significant nature conservation and human health gains, and from the hunter’s perspective will enhance societal acceptance of hunting. Change will create opportunities for improved constructive dialogue between hunting stakeholders and others engaged with enhancing biodiversity and nature conservation objectives.
Article
Lead (Pb) is an environmental pollutant and has toxic effect on birds. Selenium (Se) has alleviative effect on Pb poisoning. This study investigated mitigative effect of Se on autophagy in Pb-treated chicken testes. Seven-day-old male chickens were randomly divided into four groups with 45 birds in each group. The birds of the control group were offered drinking water (DW) and commercial diet (CD) (0.49 mg/kg Se). The birds of the Se group were offered DW and CD containing sodium selenite (SeCD) (1.00 mg/kg Se). The birds of the Pb group were offered DW containing lead acetate (PbDW) (350.00 mg/L Pb) and CD. The birds of the Pb/Se group were offered PbDW and SeCD. On the 30th, 60th, and 90th days, respectively; histology, antioxidant indexes (hydrogen peroxide (H2O2), catalase (CAT), total antioxidant capacity (TAOC), reduced glutathione (GSH), and superoxide dismutase (SOD)), mRNA and protein levels of autophagy-related genes (autophagy-related proteins 5, Beclin 1, Dynein, light chain 3 (LC3)-I, LC3-II, and mammalian target of rapamycin (mTOR)) were performed in chicken testes. The results of this study showed that Pb caused histological changes; increased H2O2 content; decreased CAT, TAOC, and SOD activities and GSH content; and increased mRNA and protein levels of the above autophagy-related genes except that mTOR decreased in chicken testes. Se alleviated the above changes. Se alleviated histological damage, oxidative stress, and autophagy in the Pb-treated chicken testes.
Article
Lead poisoning from spent ammunition is known to affect many avian species. Birds of prey ingest lead when feeding on game shot with lead gunshot or bullets. Raptors with scavenging habits are particularly vulnerable to ingesting lead in areas with intensive hunting and are good indicators of the risk of poisoning from lead ammunition. To assess how much facultative and obligate avian scavengers suffer lead contamination in south-central Europe, between 2005 and 2019 we collected and analysed 595 tissue samples from 252 carcasses of 4 species (golden eagle, bearded vulture, griffon vulture, cinereous vulture). Lead concentrations in organs showed a similar pattern across species with long and small bones revealing the highest median values (5.56 and 6.8 mg/kg w.w., respectively), the brain the lowest (0.12), and the liver and kidney the intermediate (0.47 and 0.284). Overall, 111 individuals (44.0%) had lead concentrations above background thresholds in at least one tissue (i.e. >2 mg/kg w.w. in soft tissues, >8.33 in bone) and 66 (26.2%) had values indicating clinical poisoning (>6 mg/kg w.w. in liver, >4 in kidney, >16.6 in bone). Tissue lead concentrations and incidence of clinical and sub-clinical poisoning were higher in golden eagles and griffon vultures than in bearded and cinereous vultures, likely due to different feeding habits. In all species we found a rapid increase in lead values with age, but differences between age classes were significant only in the golden eagle. Birds with lead fragments in their digestive tract, as detected by X-rays, had higher median lead concentrations, suggesting that hunting ammunition is the main source of lead poisoning. Our results imply that lead impacts the demography of these long-lived species with delayed sexual maturity and low reproduction rate. A rapid transition towards lead-free bullets and gunshot is therefore required across Europe.
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The Atacama Desert represents the highest levels of mining exploitation in Chile, which inexorably results in high levels of pollution. Raptors, and particularly scavengers, have shown their usefulness to evaluate exposure to environmental contaminants in polluted scenarios. In this study, we used primary feathers from a local avian scavenger, turkey vulture Cathartes aura, to evaluate the exposure to cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) in two locations from the southern Atacama Desert (coastal and inland) and a third location from the bordering semiarid region, in northern Chile. All metals were detected in all analyzed samples (n = 54). Mean concentrations in Coastal Atacama were 0.68 ± 0.84 ppm for Cd; 1.97 ± 2.01 ppm for Pb; 59.11 ± 80.69 ppm for Cu; and 107.96 ± 51.00 ppm for Zn, while mean concentrations in Inland Atacama were 0.55 ± 0.42 ppm for Cd; 3.37 ± 2.61 ppm for Pb; 91.66 ± 77.74 ppm for Cu; and 214.03 ± 99.08 ppm for Zn. Mean concentrations in Coastal Coquimbo were 0.63 ± 0.69 ppm for Cd; 1.57 ± 0.92 ppm for Pb; 18.09 ± 6.12 ppm for Cu; and 149.37 ± 105.56 ppm for Zn. These differences could be explained by differences on abundance of mining settlements among areas. According to the literature, these values are very high for all metals, exceeding in some cases those values referred as responsible of health disorders in birds. We strongly recommend further research looking at potential adverse effects caused by heavy metal pollution on the health of human and wildlife populations in the southern Atacama Desert.
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Accurate estimations of adult mortality are essential for understanding population dynamics and achieving efficient management actions that are directed toward long-lived species. Several noninvasive methods may be used to monitor endangered long-lived birds like raptors, but their performance in real-world scenarios remains poorly studied. We used eight Bonelli's Eagle (Aquila fasciata) breeding pairs (1) to compare the efficiency of direct observations with binoculars and telescopes (2004–2016), camera trapping (2012–2016), and feather genetic analysis (2004–2015) for detecting and identifying individuals over time, (2) to conduct a cost-benefit analysis of methods, and (3) to evaluate the accuracy of the direct observation method for estimating survival by comparing it with camera trapping and feather analysis. Both the feather genetic analysis and camera trapping approaches allowed us to successfully identify individuals and to detect replacements that we did not notice during direct observations. The classic direct observation method overestimated adult survival, which could hamper an accurate understanding of the demographic dynamics of this population. Feather analysis gave a low detection rate of individuals (47%), probably due to difficulties in finding feathers in the rugged habitat of this species. However, identification success at the individual level with this method was 96%. Remote camera surveys had both a high detection rate (100%) and identification success (93%). Given that costs associated with camera surveys were lower than the costs of genetic procedures, we concluded that camera trapping is the most efficient indirect method to assess adult survival in this and other raptors with external features that make individual identification possible. However, because no method showed complete efficiency, genotyping of feathers collected at the end of the breeding season could be a useful additional method, especially when camera trapping is not possible or when it fails.
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Poisoning of wild birds following ingestion of lead from ammunition has long been recognised and considerable recent research has focused on terrestrial birds, including raptors and scavengers. This paper builds upon previous reviews and finds that both the number of taxa affected and geographical spread of cases has increased. Some lead may also be absorbed from embedded ammunition fragments in injured birds which risk sub-lethal and welfare effects. Some papers suggest inter-specific differences in sensitivity to lead, although it is difficult to disentangle these from other factors that influence effect severity. Sub-lethal effects have been found at lower blood lead concentrations than previously reported, suggesting that previous effect-level ‘thresholds’ should be abandoned or revised. Lead poisoning is estimated to kill a million wildfowl a year in Europe and cause sub-lethal poisoning in another ≥ 3 million. Modelling and correlative studies have supported the potential for population-level effects of lead poisoning in wildfowl, terrestrial birds, raptors and scavengers.
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Lead (Pb) is a toxic element banned from fuel, paint and many other products in most developed countries. Nonetheless, it is still widely used in ammunition, including rifle bullets, and Pb-based bullets are almost universally used in Australia. For decades, poisoning from Pb shot (shotguns) has been recognised as a cause of disease in waterfowl and Pb shot has been subsequently banned for waterfowl hunting in many jurisdictions. However, the risks posed by Pb-based bullets (rifles) have not been similarly recognised in Australia. Pb-based rifle bullets frequently fragment, contaminating the tissue of shot animals. Consuming this Pb-contaminated tissue risks harmful Pb exposure and, thus, the health of wildlife scavengers (carrion eaters) and humans and their companion animals who consume harvested meat (game eaters). In Europe, North America and elsewhere, the environmental and human health risks of Pb-based bullets are widely recognised, and non-toxic alternatives (e.g. copper-based bullets) are increasingly being used. However, Australia has no comparable research despite widespread use of shooting, common scavenging by potentially susceptible wildlife species, and people regularly consuming shot meat. We conclude that Australia has its collective ‘head in the sand’ on this pressing worldwide One Health issue. We present the need for urgent research into this field in Australia.
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Scavenging and predatory wildlife can ingest lead (Pb) from lead-based ammunition and become poisoned when feeding on shot game animals. Humans can similarly be exposed to ammunition-derived lead when consuming wild-shot game animals. Studies have assessed the degree of lead contamination in the carcasses of game animals but this scrutiny has not so far extended to Australia. Stubble quail (Coturnix pectoralis) are one of the only native non-waterfowl bird species that can be legally hunted in Australia, where it is commonly hunted with lead shot. The aim of this study was to characterize lead contamination in quail harvested with lead-based ammunition. The frequency, dimensions, and number of lead fragments embedded in carcasses were assessed through use of radiography (X-ray). From these data, the average quantity of lead available to scavenging wildlife was estimated along with potential risks to human consumers. We radiographed 37 stubble quail harvested by hunters using 12-gauge (2.75") shotguns to fire shells containing 28 g (1 oz) of #9 (2 mm or 0.08" diameter) lead shot in western Victoria, Australia, in Autumn 2021. Radio-graphs revealed that 81% of carcasses contained embedded pellets and/or fragments with an average of 1.62 embedded pellets detected per bird. By excising and weighing a sample of 30 shotgun pellets (all had a mass of 0.75 grain or 48.6 mg), we calculated an average lead load of 78 mg/100 g of body mass. This was a conservative estimate, because fragments were not considered. This level of lead contamination was comparable to hunted bird species examined using similar methods in Europe. The quantity and characteristics of lead ammunition residues found suggest that predatory and scavenging wildlife and some groups of human consumers will be at risk of negative health impacts.
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Birds of prey have been, in comparison to other avian groups, an uncommon study model, mainly due to the limitations imposed by their conservative life strategy (low population density and turnover). Nonetheless, they have attracted a strong interest from the point of view of conservation biology because many populations have been close to extinction and because of their recognised role in ecosystems as top predators and scavengers and as flagship species. Today, after more than a century of persecution, and with the exception of some vultures still very much affected by illegal poisoning, many populations of birds of prey have experienced significant recoveries in many regions of Spain and the European Mediterranean. These changes pose new challenges when addressing the conservation of raptors in the coming decades. On this basis, and from a preferentially Mediterranean perspective, we have focused our attention on the need of describing and quantifying the role of these birds as providers of both regulating (rodent pest control and removal of livestock carcasses) and cultural ecosystem services. Moreover, we revisited persisting conflicts with human interests (predation of game species) and call attention to the emergence of new conflicts with a strong social and media component such as the predation on live cattle by vultures. Also, the rampant humanization of the environment determines the need for new solutions to the growing, yet scarcely explored, problem of accidents in new infrastructures such as mortality in wind farms. Finally, we explored in depth the ecological response of birds of prey to large-scale habitat changes such as urbanisation and abandonment of marginal lands that are also expected to increase in the near future. We urgently need more scientific knowledge to provide adequate responses to the challenge of keeping healthy populations of avian predators and scavengers in a rapidly changing world.
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The doctor-patient relationship is the gateway to the completion of the medical history and to know the suffering of his patient. In establishing this relationship, there should be a real linking / connection between the interacting ones, where they influence each other by being able to communicate feelings and thoughts, not only resulting from the organic affection but also the discomfort or indisposition for emotional, situational conflicts , labor and sociocultural. Once the patient is recognized as the center of attention, the effect of the contextual variables, the theoretical perspective, the care model of the health institutions and the orientation of the medical service providers, in addition to the culture of the patients, Four approaches are considered to establish the model of human communication to be followed in the doctor - patient relationship; The medical interview, psychological interview, psychiatric interview and anthropological interview. Each one expresses the historical evolution of medicine, from a biomedical approach with the contribution of scientific / technological advances to the incorporation of elements of transpersonal psychology, sociology, linguistics, education, computer science and communication sciences. La relación médico-paciente es la puerta de entrada para la realización de la historia clínica y conocer el padecer de su paciente. En el establecimiento de esta relación conviene que exista una vinculación/conexión real entre los interactuantes, donde se influyan mutuamente al estar en posibilidad de comunicar sentimientos y pensamientos, no solo derivados de la afección orgánica sino también el malestar o indisposición por conflictos emocionales, situacionales, laborales y socioculturales. Una vez reconocido el paciente como centro de atención, el efecto de las variables contextuales, la perspectiva teórica, el modelo de atención de las instituciones de salud y la orientación de los médicos prestadores de servicios, - amén de la cultura de los pacientes - , se consideran cuatro abordajes para establecer el modelo de comunicación humana que se ha de seguir en la relación médico - paciente; la entrevista médica, entrevista psicológica, entrevista psiquiátrica y entrevista antropológica. Cada una expresa la evolución histórica que ha tenido la medicina, desde un enfoque biomédico con aporte de los adelantos científicos/ tecnológicos hasta la incorporación de elementos de psicología transpersonal, sociología, lingüística, educación, informática y ciencias de la comunicación.
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Description Fit linear and generalized linear mixed-effects models. The models and their components are represented using S4 classes and methods. The core computational algorithms are implemented using the 'Eigen' C++ library for numerical linear algebra and 'RcppEigen' ``glue''.
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Avian ecotoxicology studies the movement of environmental contaminants through ecosystems and their harmful effects on birds. Birds are recognized as valuable indicators and biomonitors of environmental quality, and recently also as sentinels of potential risks for human health. Special attention has been paid to studying chemical compounds able to interfere with endocrine systems altering reproduction and behavior in birds, and, consequently, as potential causes of population decline. Organochlorine compounds, metals, industrial chemicals, veterinary drugs, and pesticides are the chemicals most frequently described as hazardous to bird populations. Finally, data from experimental tests to determine the safety of pesticides and industrial chemicals are required.
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Lead (Pb) is a metabolic poison that can negatively influence biological processes, leading to illness and mortality across a large spectrum of North American avifauna (>120 species) and other organisms. Pb poisoning can result from numerous sources, including ingestion of bullet fragments and shot pellets left in animal carcasses, spent ammunition left in the field, lost fishing tackle, Pb-based paints, large-scale mining, and Pb smelting activities. Although Pb shot has been banned for waterfowl hunting in the United States (since 1991) and Canada (since 1999), Pb exposure remains a problem for many avian species. Despite a large body of scientific literature on exposure to Pb and its toxicological effects on birds, controversy still exists regarding its impacts at a population level. We explore these issues and highlight areas in need of investigation: (1) variation in sensitivity to Pb exposure among bird species; (2) spatial extent and sources of Pb contamination in habitats in relation to bird exposure in those same locations; and (3) interactions between avian Pb exposure and other landscape-level stressors that synergistically affect bird demography. We explore multiple paths taken to reduce Pb exposure in birds that (1) recognize common ground among a range of affected interests; (2) have been applied at local to national scales; and (3) engage governmental agencies, interest groups, and professional societies to communicate the impacts of Pb ammunition and fishing tackle, and to describe approaches for reducing their availability to birds. As they have in previous times, users of fish and wildlife will play a key role in resolving the Pb poisoning issue.
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http://www.peregrinefund.org/subsites/conference-lead/2008PbConf_Proceedings.htm
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Published results concerning metal levels in feathers of birds of prey were listed and evaluated. Mercury concentrations have been studied most and the background values normally vary between 0.1 and 5 mg/kg dry weight the highest concentrations being in birds from aquatic food chains. Pollution causes elevated levels of mercury in feathers. The concentrations of cadmium, copper, lead and zinc show reasonable variation between species, areas and time periods. Feathers of birds of prey have proved to be good indicators of the status of environmental heavy metal pollution. Special attention should be paid to clean sampling and preparation of samples. Interpretation of the results requires knowledge on food habit, molting and migration patterns of the species. Several species representing different food chains should be included in comprehensive monitoring surveys. Chick feathers reflect most reliably local conditions.
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Lead poisoning in birds was described in Europe at the end of the 19 th century, but the first epidemiological studies were not done until the second half of the 20 th century. So far, most work has fo- cused on waterfowl and birds of prey, with very few reports evaluating the impact on upland game birds. The density of lead shot in sediments of wetlands has been studied in several countries, with maximal den- sities observed in southern Europe where up to 399 shot/m 2 in the upper 30 cm of sediment has been re- ported. Similarly, the highest prevalence of lead shot ingestion has been found in waterfowl wintering in the dry Mediterranean region, where birds concentrate in a limited number of wetlands which have also been intensively hunted for decades. If we consider the Mallard (Anas platyrhynchos) as a bioindicator spe- cies, the prevalence of lead shot ingestion varies from 2-10% in the wetlands of northern Europe, up to 25- 45% in the Mediterranean deltas in southern Europe. The species with the highest prevalence of lead shot ingestion are the Northern Pintail (Anas acuta) and the Common Pochard (Aythya ferina) with values around 60-70%. Lead poisoning has been identified as an important cause of death for the endangered White-headed Duck (Oxyura leucocephala) and for swans (Cygnus sp.). The accumulation of lead shot in upland ecosystems was recently studied in intensively hunted areas and estates used for driven shooting of Red-legged Partridge (Alectoris rufa) where densities of 7.4 shot/m 2 in soil prevailed. Prevalence of lead shot ingestion in Red-legged Partridge varies between 1.4% in Britain and 3.9% in Spain. Cases of lead poisoning have also been described in Grey Partridge (Perdix perdix, 1.4% of birds found dead), Common Pheasant (Phasianus colchicus), and Wood Pigeon (Columba palumbus). Lead poisoning has been described in 17 species of birds of prey in Europe, some of which have been near- threatened (NT) such as the White-tailed Eagle (Haliaeetus albicilla), or endangered (EN), specifically, the Spanish Imperial Eagle (Aquila adalberti). Some studies have been conducted to evaluate the exposure in populations of raptors based on tissue analysis or the presence of lead shot in regurgitated pellets. Signifi- cant rates of lead shot ingestion have been observed in the Spanish Imperial Eagle (11% of pellets with lead shot). Further, 26-40% of Marsh Harriers (Circus aeruginosus) had blood lead >30 µg/dL, 91% of Griffon Vultures (Gyps fulvus) had blood lead >20 µg/dL, and 28% of White-tailed Eagles found dead or moribund had liver lead >5 µg/g (wet weight). The ban on lead shot for hunting in wetlands, and/or for the hunting of waterbirds, was adopted by Den- mark in 1985, and some years later by Norway, the Netherlands, Finland and Sweden. Other European countries agreed to implement bans on the use of lead for shooting over wetlands by the year 2000 following the African Eurasian Migratory Waterbird Agreement (AEWA). However, only Denmark, Norway, and the Netherlands have extended the ban to all hunted species. Received 22 May 2008, accepted 6 September 2008.
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The main purpose of this study was to monitor exposure to lead and cadmium in wild birds in Murcia, a southeastern region of Spain on the Mediterranean coast. This region lies on one of the African-European flyways. Samples of liver, kidney, brain, bone, and whole blood from several species of wild birds were obtained during 1993. We found a clear relationship between cadmium and lead concentrations in birds and their feedings habits. Vultures (Gyps fulvus) had the highest concentrations of lead (mean 40 μg/dl in blood), and seagulls (Larus argentatus and Larus ridibundus) the highest concentrations of cadmium (mean 4.43 μg/g in kidney). Insectivores had high concentrations of both metals, and diurnal and nocturnal raptors showed the lowest tissue concentrations. The finding that tissue and blood concentrations were generally not elevated suggests environmental (rather than acute) exposure. Birds from more industrialized areas of the region studied here had higher concentrations of both lead and cadmium.
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Endangered species recovery programs seek to restore populations to self-sustaining levels. Nonetheless, many recovering species require continuing management to compensate for persistent threats in their environment. Judging true recovery in the face of this management is often difficult, impeding thorough analysis of the success of conservation programs. We illustrate these challenges with a multidisciplinary study of one of the world's rarest birds-the California condor (Gymnogyps californianus). California condors were brought to the brink of extinction, in part, because of lead poisoning, and lead poisoning remains a significant threat today. We evaluated individual lead-related health effects, the efficacy of current efforts to prevent lead-caused deaths, and the consequences of any reduction in currently intensive management actions. Our results show that condors in California remain chronically exposed to harmful levels of lead; 30% of the annual blood samples collected from condors indicate lead exposure (blood lead ≥ 200 ng/mL) that causes significant subclinical health effects, measured as >60% inhibition of the heme biosynthetic enzyme δ-aminolevulinic acid dehydratase. Furthermore, each year, ∼20% of free-flying birds have blood lead levels (≥450 ng/mL) that indicate the need for clinical intervention to avert morbidity and mortality. Lead isotopic analysis shows that lead-based ammunition is the principle source of lead poisoning in condors. Finally, population models based on condor demographic data show that the condor's apparent recovery is solely because of intensive ongoing management, with the only hope of achieving true recovery dependent on the elimination or substantial reduction of lead poisoning rates.
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Aim To explore the influence of an emerging infectious disease (EID) affecting a prey species on the spatial patterns and temporal shifts in the diet of a predator over a large geographical scale. We reviewed studies on the diet of Bonelli’s eagles (Hieraaetus fasciatus) in order to determine the repercussions of the reduction in the density of its main prey, the rabbit (Oryctolagus cuniculus), caused by outbreaks of rabbit haemorrhagic disease (RHD) since 1988. Location Western continental Europe. Methods We compiled published and unpublished information on the diet of breeding Bonelli’s eagles from Portugal, Spain and France for a 39-year study period (1968–2006). Nonparametric tests were used in order to analyse temporal shifts in diet composition and trophic diversity (H′) between the periods of ‘high’ (before outbreak of RHD) and ‘low’ rabbit density (after outbreak of RHD). A combination of hierarchical agglomerative clustering and non-metric multidimensional scaling (NMDS) analyses were used to test for the existence of geographical patterns in the diet of Bonelli’s eagles in each period. Results The diet of the Bonelli’s eagle consisted of rabbit (28.5%), pigeons (24.0%), partridges (15.3%), ‘other birds’ (11.6%), ‘other mammals’ (7.1%), corvids (7.0%), and herptiles (6.4%). However, RHD had large consequences for its feeding ecology: the consumption of rabbits decreased by one-third after the outbreak of RHD. Conversely, trophic diversity (H′) increased after outbreak of RHD. At the same time, the analyses showed clear geographical patterns in the diet of the Bonelli’s eagle before, but not after, RHD outbreak. Main conclusions Geographical patterns in the diet of the Bonelli’s eagle in western Europe seem to be driven mainly by spatio-temporal variation in the abundance of rabbits and, to a lesser extent, by the local (territorial) environmental features conditioning the presence and density of alternative prey species. We show that an EID can disrupt predator–prey relationships at large spatial and temporal scales through a severe decline in the population of the main prey species. Hence we argue that strict guidelines should be drawn up to prevent human-aided dissemination of ‘pathogen pollution’, which can threaten wildlife not only at the population and species level but also at the community and ecosystem scale.
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Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron percnopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10–1780 μg L−1n = 137; Iberian Peninsula range: 5.60–217.30 μg L−1n = 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.
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How predators impact on prey population dynamics is still an unsolved issue for most wild predator-prey communities. When considering vertebrates, important concerns constrain a comprehensive understanding of the functioning of predator-prey relationships worldwide; e.g. studies simultaneously quantifying 'functional' and 'numerical responses' (i.e., the 'total response') are rare. The functional, the numerical, and the resulting total response (i.e., how the predator per capita intake, the population of predators and the total of prey eaten by the total predators vary with prey densities) are fundamental as they reveal the predator's ability to regulate prey population dynamics. Here, we used a multi-spatio-temporal scale approach to simultaneously explore the functional and numerical responses of a territorial predator (Bonelli's eagle Hieraaetus fasciatus) to its two main prey species (the rabbit Oryctolagus cuniculus and the red-legged partridge Alectoris rufa) during the breeding period in a Mediterranean system of south Spain. Bonelli's eagle responded functionally, but not numerically, to rabbit/partridge density changes. Type II, non-regulatory, functional responses (typical of specialist predators) offered the best fitting models for both prey. In the absence of a numerical response, Bonelli's eagle role as a regulating factor of rabbit and partridge populations seems to be weak in our study area. Simple (prey density-dependent) functional response models may well describe the short-term variation in a territorial predator's consumption rate in complex ecosystems.
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Predation may potentially lead to negative effects on both prey (directly via predators) and predators (indirectly via human persecution). Predation pressure studies are, therefore, of major interest in the fields of theoretical knowledge and conservation of prey or predator species, with wide ramifications and profound implications in human-wildlife conflicts. However, detailed works on this issue in highly valuable--in conservation terms--Mediterranean ecosystems are virtually absent. This paper explores the predator-hunting conflict by examining a paradigmatic, Mediterranean-wide (endangered) predator-two prey (small game) system. We estimated the predation impact ('kill rate' and 'predation rate', i.e., number of prey and proportion of the prey population eaten, respectively) of Bonelli's eagle Aquila fasciata on rabbit Oryctolagus cuniculus and red-legged partridge Alectoris rufa populations in two seasons (the eagle's breeding and non-breeding periods, 100 days each) in SE Spain. The mean estimated kill rate by the seven eagle reproductive units in the study area was c. 304 rabbits and c. 262 partridges in the breeding season, and c. 237 rabbits and c. 121 partridges in the non-breeding period. This resulted in very low predation rates (range: 0.3-2.5%) for both prey and seasons. The potential role of Bonelli's eagles as a limiting factor for rabbits and partridges at the population scale was very poor. The conflict between game profitability and conservation interest of either prey or predators is apparently very localised, and eagles, quarry species and game interests seem compatible in most of the study area. Currently, both the persecution and negative perception of Bonelli's eagle (the 'partridge-eating eagle' in Spanish) have a null theoretical basis in most of this area.
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Hyperpredation refers to an enhanced predation pressure on a secondary prey due to either an increase in the abundance of a predator population or a sudden drop in the abundance of the main prey. This scarcely documented mechanism has been previously studied in scenarios in which the introduction of a feral prey caused overexploitation of native prey. Here we provide evidence of a previously unreported link between Emergent Infectious Diseases (EIDs) and hyperpredation on a predator-prey community. We show how a viral outbreak caused the population collapse of a host prey at a large spatial scale, which subsequently promoted higher-than-normal predation intensity on a second prey from shared predators. Thus, the disease left a population dynamic fingerprint both in the primary host prey, through direct mortality from the disease, and indirectly in the secondary prey, through hyperpredation. This resulted in synchronized prey population dynamics at a large spatio-temporal scale. We therefore provide evidence for a novel mechanism by which EIDs can disrupt a predator-prey interaction from the individual behavior to the population dynamics. This mechanism can pose a further threat to biodiversity through the human-aided disruption of ecological interactions at large spatial and temporal scales.
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Initial studies on the pressure from environmental contaminants on raptor populations in Spain date back to the 1980s, and they have been carried out from a range of viewpoints using a range of sentinel raptor species. However, there is no national monitoring scheme, and therefore the research carried out has been sporadic both spatially and temporally. The exposure to metals has not varied over time, except in the case of lead, whose concentration in eggs and tissues has diminished. In general, the concentrations of metals detected in raptor samples from Spain are generally low and not sufficient to produce toxic effects. Excepting DDT and DDE, most organochlorine-based pesticides in raptors from Spain have diminished over the last 2 decades. The concentrations of DDE found in the eggs of various species could in part explain problems in the reproductive success of raptors in Spain.
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We compared 3 methods of studying diets of Bonelli's eagle (Hieraaetus fasciatus): (1) recent prey present in the nest; (2) remains collected in the nest after breeding; and (3) pellet contents, with the delivered prey by the eagles in 2 nests. Remains collected after breeding was the only method that differed (P = 0.001) from delivered prey by underestimating small prey, especially red squirrel (Sciurus vulgaris) and ocellated lizard (Lacerta lepida), and overestimated pigeons (Columba spp). Study of prey consumption patterns showed that small prey frequently were fully consumed but remains were often left from medium and large prey. Rabbits (Oryctolagus cuniculus), the largest prey, appeared in similar proportions to those in which they were delivered, probably due to the fact that the eagles removed the largest bones from the nest. Although the recent-prey-present method did not show significant differences (P = 0.730) from delivered prey, the method could hide some biases linked to the greater probability of detecting large prey such as rabbits. Considering the accuracy and the effort involved in obtaining information, we conclude that pellet analysis is the most efficient method of monitoring the diet of Bonelli's eagle.
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The use of both linear and generalized linear mixed-effects models (LMMs and GLMMs) has become popular not only in social and medical sciences, but also in biological sciences, especially in the field of ecology and evolution. Information criteria, such as Akaike Information Criterion (AIC), are usually presented as model comparison tools for mixed-effects models. The presentation of variance explained' (R2) as a relevant summarizing statistic of mixed-effects models, however, is rare, even though R2 is routinely reported for linear models (LMs) and also generalized linear models (GLMs). R2 has the extremely useful property of providing an absolute value for the goodness-of-fit of a model, which cannot be given by the information criteria. As a summary statistic that describes the amount of variance explained, R2 can also be a quantity of biological interest. One reason for the under-appreciation of R2 for mixed-effects models lies in the fact that R2 can be defined in a number of ways. Furthermore, most definitions of R2 for mixed-effects have theoretical problems (e.g. decreased or negative R2 values in larger models) and/or their use is hindered by practical difficulties (e.g. implementation). Here, we make a case for the importance of reporting R2 for mixed-effects models. We first provide the common definitions of R2 for LMs and GLMs and discuss the key problems associated with calculating R2 for mixed-effects models. We then recommend a general and simple method for calculating two types of R2 (marginal and conditional R2) for both LMMs and GLMMs, which are less susceptible to common problems. This method is illustrated by examples and can be widely employed by researchers in any fields of research, regardless of software packages used for fitting mixed-effects models. The proposed method has the potential to facilitate the presentation of R2 for a wide range of circumstances.
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We derive a model that has one predator and one prey species and includes antipredator behavior. The prey are allowed to increase their investment in antipredator behavior, thereby decreasing their chance of being captured by the predator. However, they must pay for this protection by a cost exacted through decreased fecundity or increased mortality caused by factors other than predation. The population-dynamic consequences of antipredator behaviors are explored by comparing systems in which the efficiencies of the antipredator behavior differ; as the antipredator behavior becomes more efficient, the prey need to invest less in order to achieve the same level of protection from the predator. We assume that for any degree of efficiency, the prey choose their level of investment in antipredator behavior in order to optimize their expected reproductive fitness. By assuming only that the predators and prey coexist and that there is a stable equilibrium, we show that increased efficiency of antipredator behavi...
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Population viability analysis (PVA) has become a basic tool of current conservation practice. However, if not accounted for properly, the uncertainties inherent to PVA predictions can decrease the reliability of this type of analysis. In the present study, we performed a PVA of the whole western European population (France, Portugal and Spain) of the endangered Bonelli's eagle (Aquila fasciata), in which we explored thoroughly the consequences of uncertainty in population processes and parameters on PVA predictions. First, we estimated key vital rates (survival, fertility, recruitment and dispersal rates) using monitoring, ringing and bibliographic data from the period 1990-2009 from 12 populations found throughout the studied geographic range. Second, we evaluated the uncertainty about model structure (i.e. the assumed processes that govern individual fates and population dynamics) by comparing the observed growth rates of the studied populations with model predictions for the same period. Third, using the model structures suggested in the previous step, we assessed the viability of both the local populations and the overall population. Finally, we analyzed the effects of model and parameter uncertainty on PVA predictions. Our results strongly support the idea that all local populations in western Europe belong to a single, spatially structured population operating as a source-sink system, whereby the populations in the south of the Iberian Peninsula act as sources and, thanks to dispersal, sustain all other local populations, which would otherwise decline. Predictions regarding population dynamics varied considerably and models assuming more constrained dispersal predicted more pessimistic population trends than models assuming greater dispersal. Model predictions accounting for parameter uncertainty revealed a marked increase in the risk of population declines over the next 50 years. Sensitivity analyses indicated that both adult and pre-adult survival are the chief vital rates regulating these populations and thus the conservation efforts aimed at improving these survival rates should be strengthened in order to guarantee the long-term viability of the European populations of this endangered species. Overall, the study provides a framework for the implementation of multi-site PVAs and highlights the importance of dispersal processes in shaping the population dynamics of long-lived birds distributed across heterogeneous landscapes.
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During many centuries the Peregrine has epitomised the beauty and grandeur of our birds ofprey. Today, in parts of the world, its very existence is threatened by environmental pollution. In this Report to the B.T.O the author presents the results of the 1971 national census, drawing, comparisons with the catastrophic situation revealed by the first full census a decade ago, and with what is believed to have been the ‘normal’ status of this species in the 1930s. He discusses in detail the massive threat to this and all wildlife posed by the continuing deterioration in the quality of our environment, new aspects of which have been brought to light by the Enquiry. Once the joy of Kings and Princes, this noble falcon has now assumed a new mantle, ‘an ecological barometer’ of importance to Everyman.
Article
Lead poisoning of waterfowl, through the ingestion of spent gunshot, has been recognized as a mortality factor for over a century. However, in Europe relatively little attention has been paid to raptors that may ingest shot embedded in the flesh of prey. The present study examines the incidence of lead poisoning in wild Marsh Harriers Circus aeruginosus trapped at two sites in France, the Camargue and Charente-Maritime. Eight captive Marsh Harriers (controls) had blood lead (PbB) concentrations of 5.3–10.8 μg per dl. Of 94 wild birds trapped during the winters of 1990/1991 and 1991/1992 either in baited clap traps or in mist nets at night roosts, 29 (31%) had elevated (>30 μg/dl) PbB concentrations and 13 (14%) had concentrations indicative of clinical poisoning (> 60 μg/dl). Similar percentages of birds caught using the two trapping methods had elevated (>30 μg/dl) PbB concentrations. However, clap netting appeared to select for more heavily contaminated birds and for juvenile birds, although the two are not necessarily correlated. In the Camargue, significantly more females than males trapped in clap nets had elevated PbB concentrations. The incidence of shot in regurgitated Marsh Harrier pellets increased significantly between October and December, indicating increased exposure to lead as the hunting season progressed. There appeared to be a parallel increase in PbB concentrations throughout the hunting season, although this could not be clearly demonstrated as sex ratios were different during different sampling periods. Elevated PbB concentrations of harriers in the Camargue are likely to result primarily from the ingestion of shot in the flesh of crippled or unretrieved waterfowl and in Charente-Maritime, from eating crippled or dead mammals. Other raptors at risk from lead poisoning and solutions to this problem are discussed.
Article
Bonelli's Eagle Aquila fasciata is one of the rarest birds of prey in Europe, where it has suffered a significant decline in recent decades. We present information on the home-ranges and spatial parameters of 18 Bonelli's Eagles radiotracked in 2002-2006 in Catalonia (northeast Spain) and describe the home-range probability kernel, distances moved, breeding area eccentricity, territorial overlap, nearest neighbour distance and breeding site fidelity, and assess the influence of sex, breeding status, season and geographical area on these parameters. Median home-range according to the minimum convex polygon (MCP) and 95% kernel were 50.3 and 36.1 km 2, respectively. The median breeding area eccentricity was 1477 m. There was considerable overlap in the home-range of both sexes within pairs (MCP: 71.4% and 95% kernel: 98.5%), indicating close pair bonding and similar foraging patterns. Overlap in home-ranges of up to 15% between neighbouring individuals also occurred and was positively related to breeding pair density. There was no difference in spatial parameters between sexes or with breeding status, but during the non-breeding season Eagles had larger home-ranges and stayed further from nests. The high consistency across birds suggests a pattern of spatial use that is characteristic of this species. The high level of use of breeding areas and their surroundings (50% kernel) throughout the year makes it important that these areas be protected from human disturbance. Additionally, it is necessary that heavily used areas away from nesting sites, which are used for foraging and roosting, are identified, protected and managed in a sustainable fashion.
Article
This paper reports on lead contamination in marsh harriers Circus aeruginosus throughout the year. Blood samples were taken from pulli, fledged (first year) birds and adults. The results show very low blood lead (PbB) concentrations in pulli (median 0·8 μg/dl PbB). A marked seasonal difference in the distribution of PbB concentrations in first year/adult birds was found. Significantly more birds had an elevated ( > 30 μg/dl or > 60 μg/dl) PbB concentrations within than outside the hunting season, reflecting different levels of exposure to lead shot during these periods. In addition, a high proportion of regurgitated marsh harrier pellets contained lead shot during the hunting season (autumn/winters 1994 and 1995—25% and 15·6%, respectively), whilst only 1·4% of pellets contained shot during spring 1994, after the hunting season. These results provide compelling evidence that spent lead shot carried in the carcasses of prey is the source of lead contamination in marsh harriers in Charente-Maritime.
Article
Red-tailed hawks were exposed to sublethal levels of lead acetate for periods of 3 or 11 weeks. Alterations in the heme biosynthetic pathway were demonstrated after the first week of exposure to 0.82 mg lead per kilogram body weight per day. Activity of erythrocyte porphobilinogen synthase (aminolevulinic acid dehydratase) was depressed significantly and did not return to normal levels until 5 weeks after the termination of lead treatments. A rapid and relatively brief increase in erythrocyte free protoporphyrin and a slower but more prolonged increase in its zinc complex were also demonstrated with exposure to this dose of lead for 3 weeks. Less substantial decreases in hematocrit and hemoglobin levels occurred but only in the longer experiment with exposure to higher lead levels. Short term, low level lead exposure did not effect immune function significantly in the hawks, as measured by antibody titers to foreign red blood cells or by the mitogenic stimulation of T-lymphocytes. Increased lead exposure produced a significant decrease in the mitogenic response but had no effect on antibody titers.