Organochlorine residues in blood of cinereous vultures and Eurasian griffon vultures in a northeastern Mediterranean area of nature conservation

Levels of persistent organic pollutants (POPs) and the role of anthropic subsidies in the diet of avian scavengers tracked by stable isotopes

Persistent Organic Pollutants (POPs) have been identified as a significant factor driving declines in wildlife populations. These contaminants exhibit a dual tendency to biomagnify up the food chains and persist within tissues, rendering long-lived vertebrates, such as raptors, highly vulnerable to their adverse effects. We assessed the concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in fledglings of two vulture species, the Egyptian vulture (Neophron percnopterus) and the griffon vulture (Gyps fulvus), coexisting in northern Spain. Vultures, currently facing a severe threat with a population decline exceeding 90%, represent one of the most critically endangered avian groups in the Old World. Despite this critical situation, there remains a scarcity of research examining the intricate relationship between contaminant levels and individual foraging behaviors. In parallel, we analyzed stable isotope levels (δ15N and δ13C) in fledgling's feathers and prey hair to determine the association between individual dietary and contaminant burdens. Our findings revealed higher levels of PCBs in Egyptian vultures, while pesticide concentrations remained very similar between focal species. Furthermore, higher individual values of δ13C, indicating a diet based on intensive farming carcasses and landfills, were associated with higher levels of PCBs. While the levels of POPs found do not raise immediate alarm, the presence of individuals with unusually high values reveals the existence of accessible contamination sources in the environment for avian scavengers. The increasing reliance of these birds on intensive livestock farming and landfills, due to the decline of extensive livestock farming, necessitates long-term monitoring of potential contaminant effects on their populations.

Analytical development for the assessment of pesticide contaminations in blood and plasma of wild birds: The case of grey partridges (Perdix perdix)

In this study, blood and plasma of grey partridges (Perdix perdix) were analyzed to assess their potential contamination by plant protection products (PPP) and especially pesticide compounds. The group of pesticides selected is composed of a huge variety of compounds. Therefore, in this study, two methods were optimized and validated to analyze 104 compounds including herbicides, insecticides, fungicides and photoprotectors or synergists. Various extraction methods found in the literature were compared and adapted for the extraction of pesticides from blood and plasma. After extraction, samples were concentrated then injected for quantification simultaneously in LC-MS/MS and ATD-GC-MS/MS with an automatic thermal desorption step (ATD). Both LC-MS/MS and ATD-GC-MS/MS analyses were performed using the MRM mode with 2 mass transitions for each compound.The two analytical methods achieved a good linearity for the calibration responses in plasma and blood. Methods allowed sensitive detection and quantification in complex biological matrices such as plasma and blood in both LC and GC. For plasma samples and considering all 104 compounds of the study, the average LOD was 0.005 ng mg^-1 in LC-MS/MS and 0.035 ng mg^-1 in ATD-GC-MS/MS and the average LOQ was 0.017 ng mg^-1 and 0.116 ng mg^-1 in LC-MS/MS and ATD-GC-MS/MS respectively. Accordingly, the average LOD for blood samples was 0.011 ng mg^-1 in LC and 0.028 ng mg^-1 in GC whereas the average LOQ was 0.038 ng mg^-1 and 0.094 ng mg^-1 in LC-MS/MS and ATD-GC-MS/MS respectively. Those analytical methods were then successfully applied to 70 blood samples and 35 plasma samples.

The perfect threat: Pesticides and vultures

Probably the most important threat currently affecting vultures worldwide is exposure to pesticides, both accidentally and through deliberate abuse. This is of special concern since around 70% of vulture species are threatened by human activities. However, information about this threat is sparse and geographically biased. We compiled existing knowledge about pesticide exposure in vulture species globally, providing unifying criteria to mitigate this problem with a joint global effort. Most information available about accidental exposure to pesticides in vultures is related to organochlorine pesticides. Non-lethal exposure to these compounds occurs on every continent that vultures inhabit. While concentrations of organochlorine pesticides reported in different samples appear to be too low to produce health impacts, some studies show vultures with levels compatible with health impacts. In addition, there are some reports of vultures contaminated accidentally by anticoagulant rodenticides and external antiparasitic drugs used in veterinary practices. Deliberate abuse of pesticides to poison wildlife also occurs on every continent where vultures live, affecting most (78%) vulture species. However, little information is available for some regions of America, Asia and Europe. The exact number of vultures killed due to deliberate poisoning with pesticides is not well known, but the available figures are alarming (e.g. up to 500 individuals in a single event). The most widely used pesticides affecting vulture populations, and associated with deliberate poisoning, are carbamates and organophosphorus compounds. Of particular concern is the fact that massive poisoning events with these compounds occur, in some cases, within protected areas. This suggests that if this situation is not reversed, some vulture populations could disappear. A combination of measures such as banning pesticides, controlling their distribution-acquisition and environmental education could produce better results that banning pesticides alone. If poisoning with pesticides is not stopped, this threatened avian group could inadvertently go extinct very soon.

Can variability in corticosterone levels be related to POPs and OPEs in feathers from nestling cinereous vultures (Aegypius monachus)?

Persistent organic pollutants (POPs) are still globally distributed and some have been shown to interact with the endocrine system of birds. However, the relationship between POPs and the stress response mediated by the hypothalamic-pituitary-adrenal (HPA) axis is still poorly understood. Raising concerns are now focused on the toxic properties of emergent organophosphate ester flame retardants (OPEs), but whether OPEs interact with the HPA axis response has not yet been investigated. We measured corticosterone concentrations in feathers (CORTf) as a long-term biomarker of the bird HPA axis response and we investigated their relationship with POP and OPE concentrations in down feathers of nestling cinereous vultures (Aegypius monachus). We also examined whether high contaminant burden and high CORTf concentrations impacted the duration of chick development. The most predominant compounds were the following: p,p'-DDE (3.28 ± 0.26 ng g^-1 dw) > γ-HCH (0.78 ± 0.09 ng g^-1 dw) > BDE-99 (0.73 ± 0.09 ng g^-1 dw) > CB-153 (0.67 ± 0.04 ng g^-1 dw). The most persistent POP compounds (CB-170, -177, -180, -183, -187, -194 and p,p'-DDE) were associated (P = 0.02) with high concentrations of CORTf (range: 0.55-6.09 pg mm^-1), while no relationship was found when OPEs were tested (P > 0.05). Later egg-laying was positively associated to high levels of CORTf (P = 0.02) and reduced duration of chick development (P < 0.001), suggesting a beneficial effect of the HPA axis response on the growth of the chicks. In addition, males with high concentrations of the most persistent POP compounds tended to show a reduced duration of the nestling period (P = 0.05) and an equal fledging success than chicks with lower levels. These findings suggest that POPs, but not OPEs, may interact with the HPA axis response of chicks, although levels were not high enough to cause detrimental consequences.

Animal mortality and illegal poison bait use in Greece

The present study describes the use of poison baits against so-called pest species in Greece and explores various aspects of this illegal practice. Data were collected from 2000 to 2016, and a total of 1015 poisoning incidents in rural areas causing the death of 3248 animals were examined. In 58.7% of investigated cases, the motives remained unknown; in the remaining cases, human-wildlife conflicts and retaliatory actions among stakeholders (e.g., hunters vs. livestock breeders) were found to be the main reasons for poison bait use. The target animals for these actions were mainly mammalian carnivores, and stray canids, all of which were blamed for livestock and game losses. Avian scavengers were the wildlife species most affected by secondary poisoning (30% of the wildlife fatalities), whereas shepherd dogs accounted for 66.4% of domestic animal losses. Toxicological analyses showed that a wide range of chemical substances were used, mostly legal or banned pesticides (e.g., carbamates, organophosphates, and organochlorines) and potassium cyanide. Furthermore, the widespread trafficking of black marketed insecticides was also recorded, with methomyl (in powder form) and carbofuran being most common. The majority of poisoning events (72%) took place outside protected areas, while in approximately 73.4% of them, no official reporting to the competent authorities was made. Overall, the study highlights the significant impact of illegal poison bait use on wildlife in Greece and addresses its extreme socioeconomic complexity. The need for an integrated national anti-poison strategy is discussed.

Blood concentrations of p,p'-DDE and PCBs in harriers breeding in Spain and Kazakhstan

Organochlorine compounds (OC) are of interest in current biomonitoring studies because of their well-known persistence, accumulation capacity and the adverse effects they caused in the past. P,p'-DDE has been shown to cause severe reproductive failures and population declines in birds of prey. However, there are knowledge gaps regarding OC exposure for some species (e.g. harriers), the historical record and the broader picture. The main goal was to evaluate exposure to p,p'-DDE and PCBs in two raptor species: Montagu's and pallid harriers (Circus pygargus and Circus macrourus), and to investigate if birds from different breeding areas and wintering grounds differ in pollutant levels. For this purpose, we collected blood of adult and nestling Montagu's and pallid harriers breeding in the natural steppes of Kazakhstan, and adult and nestling Montagu's harriers breeding in agricultural and natural habitats of Spain, in 2007-2008. We determined the blood concentrations of p,p'-DDE and PCBs. Adult harriers generally showed higher concentrations of p,p'-DDE and PCBs than nestlings, probably because they had more time for a progressive accumulation of these compounds due to a higher intake than excretion rate. The p,p'-DDE concentrations in adults were equivalent in all the studied areas. The ratio p,p'-DDE/PCB 153 was higher in adults than in nestlings, suggesting that a portion of the p,p'-DDE in adult harriers may have come from p,p'-DDT applied in the past in the wintering areas. Overall, the concentrations of p,p'-DDE and ∑PCBs reported were generally low and below any demonstrated threshold of harm.

Blood concentrations of PCBs and DDTs in an avian predator endemic to southern Africa: Associations with habitat, electrical transformers and diet

Persistent pollutants such as organochlorine compounds (OCs) have been highlighted as a cause of population decline in avian predators. Understanding patterns of OCs contamination can be crucial for the conservation of affected species, yet little is known on these threats to African raptors. Here we report on OC concentrations in an endangered predator endemic to southern Africa, the Black Harrier Circus maurus. Blood samples were collected in 2012-2014 from wild nestlings (n = 90) and adults (n = 23) in south-western South Africa, where agriculture and urbanization have developed rapidly since the 1950s. Polychlorinated biphenyl (ΣPCB) and dichlorodiphenyltrichloroethane (ΣDDT, for p,p'-DDT + p,p'-DDE) were detected in 79% and 84% of sampled individuals, respectively, with varying concentrations among demographic groups: nestlings had significantly higher ΣPCB and p,p'-DDT concentrations than adults, while adults had higher levels of p,p'-DDE than nestlings. Levels of ΣPCB significantly increased with an index of electric transformer density, a measure of the number and power of electric transformers around active nests. We propose this index as a useful tool for assessing ΣPCB exposure risk in other wildlife. Levels of p,p'-DDE significantly increased with the proportion of wetlands within the breeding territory, and also with the proportion of bird biomass in the diet. No association was found between OC levels and the protected area status of nesting sites. Physiological effects of contaminants were also manifest in increased white blood cell counts with higher p,p'-DDT levels. Heterophil to lymphocyte ratio increased with higher ΣPCB levels, suggesting increased physiological stress and reduced immunity in contaminated individuals. Our results suggest that OCs are still a current cause of concern for endangered Black Harriers, as well as other sympatric predators.

Pollutant accumulation patterns in nestlings of an avian top predator: biochemical and metabolic effects

The exposure to persistent pollutants such as organochlorine compounds (OCs) or metals has been associated with declines in top predator populations, which can accumulate high amounts of these pollutants from their prey. However, understanding how variation in OC and metal accumulation in wild species affects their biochemical and physiological responses is a big challenge, especially for endangered predators like the Bonelli's eagle (Aquila fasciata). This bird of prey is an interesting study model because the differences in diet composition among populations and territories can account for important pollutant uptake variations. We compared OC and metal accumulation in blood of Bonelli's eagle nestlings from three populations across Spain as a function of origin, age class (nestlings vs. adults), sex and number of siblings per nest, and related accumulation patterns to responses indicative of body condition, biochemistry and antioxidant status. Nestlings from Catalonia, the most industrialized area, showed the highest concentrations of PCBs and arsenic, and the lowest concentrations of zinc. The two former substances, together with DDTs, exerted an overall influence on nestling's physiology. PCBs and arsenic were associated with reduced retinol levels, pointing to oxidative damage in exposed individuals, which was also consistent with the low zinc levels in individuals from the polluted region. Increased plasma DDT levels were related to reduced body condition and lower levels of triglycerides. Mercury accumulation in Castile and Leon was higher in nestlings that were alone in the nest than in nestlings that shared it with a sibling; this suggests an increased mercury uptake from secondary prey in territories where preferred prey (i.e. rabbits) are scarce, which are also the territories where productivity is reduced. Overall, the results reveal a spatial variation in pollutant accumulation patterns and associated physiological effects, and suggest the major role that territory quality may have in such patterns.

Organochlorine and mercury residues in eggs of the lesser kestrel (Falco naumanni) from a long term study in the eastern Mediterranean

Organochlorine and mercury residues were analyzed in unhatched eggs of the lesser kestrel (Falco naumanni) (2002-2012) in central Greece. Concentrations graded as ∑DDTs > ∑PCBs > HCB > ∑HCHs > ∑Chlordanes. Temporal declines were found in the concentrations of ∑DDTs, ∑HCHs and ∑Chlordanes but not in Hg, HCB and ∑PCBs. TEQs of PCBs and their degree of metabolisation showed no time trend. The reproductive parameters showed neither a temporal trend nor a significant year effect. No relationships occurred between the reproductive parameters per year and nest type (natural, artificial) with any of the contaminants analyzed except HCB influenced by year and clutch size. Low pollutant concentrations suggest that either lesser kestrels ranged across the year in unpolluted areas or may be caused by their short food chain. The low concentrations seem improbable to have affected the reproduction of these birds, although critical levels are still to be defined.

Levels of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides in various tissues of white-backed vulture in India

This study provides information on the current status of contamination by polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in the tissues of endangered White-backed Vulture Gyps bengalensis in India. Chemical analyses revealed detectable amounts of PAHs, PCBs, and OCPs. Concentration ranges of ∑PAHs, ∑PCBs, and ∑OCPs in tissues were 60–2037 ng/g, 30–5790 ng/g, and 3.2–5836 ng/g wet weight, respectively. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′-DDE) concentrations ranged from below detectable level to 599 ng/g wet weight, representing more than 90% of the total dichlorodiphenyltrichloroethane (DDT). Among the various OCPs analyzed, p,p′-DDE was detected most frequently. All the contaminants recorded show higher accumulation in liver than other tissues. Levels of contaminants measured in the tissues of vulture are comparable with the levels documented in a number of avian species and are lower than those reported to have caused deleterious effects. Although no threat is expected from the current level of contamination, the presence of varying levels of contaminants and their additive or synergistic toxicity is a cause of concern to vultures. Values reported in this study can serve as guideline for future research.

Examination of Eurasian griffon vultures (Gyps fulvus fulvus) in Israel for exposure to environmental toxicants using dried blood spots

The griffon vulture (Gyps fulvus) is one of seven species of Old World Gyps vultures found over a wide range from the Iberian peninsula in the west through the Balkans, Turkey, and the Middle East to India in the east. The population of the griffon vultures in Israel has suffered a dramatic decrease, and in recent years productivity has been severely reduced. In this study, whole-blood samples taken from 25 apparently healthy griffon vultures at various stages of maturity were examined to investigate whether the vultures are being excessively exposed to environmental contaminants that might deleteriously affect their reproduction. Five groups of environmental contaminants, comprising toxic elements, organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and perfluorinated compounds, were monitored in dried blood spots. Results of the analyses showed low levels of exposure of griffon vultures to environmental contaminants compared with the sparse data available on griffon vultures and other diurnal raptors in other countries.