Milvus Milvus Research Articles

Corticosterone mediates telomere length in raptor chicks exposed to chemical mixture

Stressors experience early in life by animals may have carry over impacts on life-traits over the life cycle. Accelerated telomere attrition induced by stress during development and growth could play a role in such delayed effects. Among stressors, exposure to chemicals may modify telomere dynamic but, to date, the trends evidenced between exposure and telomere shortening remains inconsistent. Moreover, the role of corticosterone as a possible mediator of chemical impact on telomere is not yet clearly established. Here, we investigated in wild populations of Red kite whether nestling exposure to metals and pesticides was related to corticosterone concentrations in feathers and telomere length measured in 47 individuals. Lead and mercury concentrations in blood ranged from 2.3 to 59.0 µg L−1 and to 1.4 to 115.7 µg L−1, respectively, and were below the toxicity thresholds proposed for wildlife. Rodenticides were detected in 30% of the chicks. Corticosterone increased with mercury and lead in interaction, showing a synergistic effect of these 2 non-essential metals on this stress hormone. Telomere length was not linked to metals and/or rodenticide exposure while it was related negatively to corticosterone. The relationship between telomere and corticosterone was modulated by nestling’s age, which suggests that the rate of telomere shortening is higher when corticosterone increases. Our findings propose an effect of low exposure of Red Kite nestlings to mercury and lead mixture to raise baseline corticosterone in feathers. The relationships established suggest the hypothesis that telomere attrition could be an indirect consequence of metal exposure mediated by corticosterone.

Nesting of Eurasian Tree Sparrow Passer montanus in a nest of Red Kite Milvus milvus

In June 2019 we found a nest of Eurasian Tree Sparrow Passer montanus in a nest of Red Kite Milvus milvus. It contained five chicks and was located on the side of the kite nest. The nests were located 17 m above ground in a pine tree in a small pine woodland within farmland in western Poland. We believe that this is the first record of Eurasian Tree Sparrow breeding in a Red Kite nest. Our observation supports the notion of great adaptability and flexibility in selection of nest site reported by other authors, who have found Eurasian Tree Sparrow nest in large twig nests of several species.

Autumn Migration of Immature Red Kites Milvus milvus from a Central European Population

Post-fledging behaviour and mortality between the place of birth and wintering sites can be crucial to populations of raptors. We studied this phenomenon during the autumn migration of immature Red Kite Milvus milvus using telemetry data on the population breeding in western Poland. In total 34 immatures from 17 nests were ringed and GPS–GSM transmitters were attached, but only half of them survived the post-fledging period and started their first migration to wintering sites. The main mortality factors after fledging were collisions with power lines (6 individuals — 26.1%) and poisoning in wintering grounds (3 individuals — 8.8%). The mean (± SD) duration of migration and the mean distance between the breeding and wintering sites were 91.5 ± 45.2 day (range: 27–236) and 1328.0 ± 442.4 km (range: 690–2070), respectively. The daily mean speed of migration was 17.8 ± 9.4 km/day. On migration kites stopped on average 4.3 ± 3.1 times (range 1–12) for longer than 3 days, and spent a total of 37.5 ± 10.7 days (range 20–51) at stopovers. The migration duration was negatively correlated with the day of beginning of the migration, i.e. birds that started to migrate late in the season reached the wintering grounds faster. However, when the number of days at stopovers was excluded from the migration duration, this relationship was not significant, which means that the total number of days that kites spent at stopover sites significantly influenced the total duration of autumn migration. The wintering sites of birds from western Poland were located in the Iberian Peninsula and southern France and less important was Greece where single bird followed. Regular stopping over of immature Red Kites during their autumn migration indicates the need to focus more on protecting the staging areas.

Characterization of the complete mitochondrial genome of Centrorhynchus milvus (Acanthocephala: Polymorphida) and its phylogenetic implications

The phylum Acanthocephala is a small group of obligate parasites of animals. However, the current classifications of Acanthocephala are still under debate. Moreover, our present knowledge of the complete mitochondrial genome of this parasite group remains limited. To fill this knowledge gap, the complete mitochondrial (mt) genome of Centrorhynchus milvusWard, 1956 (Palaeacanthocephala: Polymorphida) was firstly sequenced and determined based on specimens collected from the red kite (Milvus milvus) in Pakistan. The mitochondrial genome of C. milvus is 14,314 bp in length and contains 36 genes, including 12 protein-coding (PCGs) genes, 22 transfer RNA (tRNA) genes and ribosomal RNA (rRNA) genes (rrnL and rrnS). To elucidate the phylogenetic relationships of the four classes of Acanthocephala and the systematic position of C. milvus, phylogenetic analysis based on concatenated amino acid sequences of 12 PCGs was performed using Bayesian inference (BI). The results supported the monophyly of Archiacanthocephala and Palaeacanthocephala with strong support (BPP = 1) and also indicated that Archiacanthocephala is the sister clade to the remaining classes of Acanthocephala (Palaeacanthocephala, Eoacanthocephala and Polyacanthocephala). However, Polyacanthocephala with only one representative species (P. caballeroi) is nested within Eoacanthocephala. Our phylogenetic analysis also confirmed C. milvus as the member of the family Centrorhynchidae with a sister relationship to C. aluconis. Our present mt genomic data are very useful for studying the molecular epidemiology, population genetics and systematics of acanthocephalans.

Quantification of anthropogenic food subsidies to an avian facultative scavenger in urban and rural habitats

The provision of anthropogenic food to wildlife is a global phenomenon, and intentional wild bird feeding has become increasingly popular in the last decades. Though there is anecdotal evidence of feeding of avian facultative scavengers in rural areas, most studies of wild bird feeding in Europe and the United States focused on passerines and urban contexts. We aim at quantifying the extent of feeding by private residents to an avian facultative scavenger, the red kite (Milvus milvus), in Swiss urban and rural areas by conducting a face-to-face systematic survey (N = 199 randomly selected houses) in a 275 km2 study area. 4.6% of urban and 12.7% of rural households regularly fed red kites. While building density negatively affected the probability of households providing food, daily anthropogenic food mass was larger in urban than in rural areas, mainly due to the higher number of households. Daily availability was also larger in winter than in the rest of the year. In total, 47–86 metric tons of anthropogenic food was provided yearly, which represents a maximum daily average of nearly 0.9 kg of food per km2. We conclude that intentional (20%) and unintentional (80%) provision of anthropogenic food to facultative scavengers are widespread and well-established human behaviors in Switzerland. These behaviors provide high food availability over the year in both rural and urban areas. The results represent an important basis for understanding the ecological consequences of anthropogenic food provisioning, human-scavenger interactions, and scavenger population dynamics in anthropogenic landscapes.

Breeding of Red Kite (Milvus milvus) confirmed in the western Po Valley

[First verified breeding of the Red Kite Milvus milvus in Piedmont, N-W Italy. The Red Kite breeds in the central and southern regions of Italy. In the North it is observed during migration and winter. In this document we verified a breeding case successfully ended with the fledging of two young birds between June 28th and July 1st 2018, in North-West Italy, in Piedmont in the province of Turin.]
 
 [Article in Italian]

A mixed pair of black and red kites in Ukraine, including DNA analysis of hybrid offspring

Red kite (Milvus milvus) is a European raptor. Kites of the nominal subspecies Milvus migrans migrans (hereafter called black kites) breed in the Western Palearctic and in Central Asia. Due to the extremely short period since their divergence, black and red kites can successfully hybridize. A mixed pair of black kite female and red kite male was observed during breeding seasons 2017 and 2018 in Poltva, Ukraine (i.e., in the easternmost part of red kites’ breeding territory). This pair produced three and three young in 2017 and 2018, respectively. DNA of the three young from 2018 was analyzed regarding their mitochondrial CytB haplotype and nuclear Myc gene alleles. All three young had a common black kite CytB haplotype. Myc alleles combinations suggest that the male parent could be not a pure red kite and could have a black kite among its ancestors. All three young from 2018 were presumed predated on or close to the nest by goshawk (Accipiter gentilis).

Protected areas under pressure: decline, redistribution, local eradication and projected extinction of a threatened predator, the red kite, in Doñana National Park, Spain

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 38:189-204 (2019) - DOI: https://doi.org/10.3354/esr00946 Protected areas under pressure: decline, redistribution, local eradication and projected extinction of a threatened predator, the red kite, in Doñana National Park, Spain Fabrizio Sergio1,*, Alessandro Tanferna1, Javier Chicano1, Julio Blas1, Giacomo Tavecchia2, Fernando Hiraldo1 1Department of Conservation Biology, Estación Biológica de Doñana - CSIC, C/Americo Vespucio 26, 41092 Seville, Spain 2Animal Demography and Ecology Unit, Institute for Mediterranean Studies (IMEDEA), CSIC-UIB, 07190 Esporles, Spain *Corresponding author: fsergio@ebd.csic.es ABSTRACT: After a period of overfocus on the establishment of reserves, attention is increasingly being devoted to the capability of protected areas to maintain viable populations of endangered species. Here, we examined the trends and reproduction of the red kite Milvus milvus, a highly endangered raptor near-endemic to Europe, to illustrate the dual benefits and challenges faced by a national park to protect this iconic species. Over the past 4 decades, the kite population of southern Spain has declined steeply and has become progressively confined to Doñana National Park and its buffering Natural Park areas. Population deterioration was also evident within the protected area through (1) spikes of rapid eradication of whole sub-populations from buffer areas, likely propelled by illegal poisoning, and (2) more gradual but steady deterioration of numbers and reproduction, especially in peripheral buffer areas, probably caused by the interplay of several shocks related to food availability, habitat degradation, competition, predation, and chemical contamination. The result was a 46-55% decline with progressive confinement to the core National Park and an alarming effective population size of <10 pairs. Demographic modelling suggested low adult survival and predicted further declines, with possible extinction over the next 2 decades. We outline tentative goals for management, but these will need urgent information on ranging and mortality to provide more efficient targets. These results illustrate how establishment of a large park can prevent regional extinction, but not necessarily guarantee species-safety, leading to protracted forms of extinction debt. We suspect that similar dynamics will become more widespread as anthropogenic pressures increase around protected areas and their performance monitoring becomes more prevalent. KEY WORDS: Matrix models · European estimates · Farmland intensification · Protected area performance · Reserves · Review · Population growth rate Full text in pdf format Supplementary material PreviousCite this article as: Sergio F, Tanferna A, Chicano J, Blas J, Tavecchia G, Hiraldo F (2019) Protected areas under pressure: decline, redistribution, local eradication and projected extinction of a threatened predator, the red kite, in Doñana National Park, Spain. Endang Species Res 38:189-204. https://doi.org/10.3354/esr00946 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 38. Online publication date: April 25, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Detection of MRSA of Lineages CC130-mecC and CC398-mecA and Staphylococcus delphini-lnu(A) in Magpies and Cinereous Vultures in Spain.

The aim of this study was to determine the carriage rate of coagulase-positive staphylococci (CoPS) in wild birds and to characterize recovered isolates. Tracheal samples from 324 wild birds, obtained in different Spanish regions during 2015-2016, were screened for CoPS carriage. The antimicrobial resistance profile and the virulence gene content were investigated. Molecular typing was performed by spa, agr, MLST, SCCmec, and S. delphini group classification. CoPS were recovered from 26 samples of wild birds (8.3%), and 27 isolates were further characterized. Two CoPS species were detected: S. aureus (n = 15; eight cinereous vultures and seven magpies) and S. delphini (n = 12; 11 cinereous vultures and one red kite). Thirteen S. aureus were methicillin-resistant (MRSA) and the remaining two strains were methicillin-susceptible (MSSA). Twelve MRSA were mecC-positive, typed as t843-ST1583/ST1945/ST1581/ST1571 (n = 11) and t1535-ST1945 (n = 1) (all of clonal-complex CC130); they were susceptible to the non-β-lactams tested. The remaining MRSA strain carried the mecA gene, was typed as t011-ST398-CC398-agrI-SCCmec-V, and showed a multiresistance phenotype. MSSA isolates were ascribed to lineages ST97-CC97 and ST425-CC425. All S. aureus lacked the studied virulence genes (lukS/F-PV, tst, eta, etb, and etd), and the IEC type E (with scn and sak genes) was detected in four mecC-positive and one MSSA isolates. S. delphini strains were methicillin-susceptible but showed resistance to at least one of the antimicrobials tested, with high penicillin (75%, with blaZ gene) and tetracycline [58%, with tet(K)± tet(L)] resistance rates. All S. delphini isolates presented the virulence genes lukS-I, siet, and se-int, and four carried the clindamycin-resistance lnu(A) gene.

Long-term decline of juvenile survival in German Red Kites

The Red Kite (Milvus milvus) is a raptor species of conservation concern in Europe and especially in Germany, where about 50% of all breeding pairs are found. Agricultural intensification and deteriorating food availability, but also anthropogenic mortality due to poisoning and collisions, are major threats for the species throughout its strongly restricted distributional range. Despite the great influence of mortality on the population size of the long-lived Red Kite, information on current age-specific survival probabilities and their change over time is lacking. We analyse a long-term dataset of > 29,000 Red Kites marked with metal rings and about 1500 recoveries of dead birds from 1970 to 2015 with a multinomial ring-recovery model. We model age-dependent recovery probability, based on separate datasets of birds marked as nestlings and as adults/immatures, and thereby estimate juvenile, subadult and adult survival probability over nearly 50 years for a major part of the German Red Kite population. The results show a substantial long-term decline in juvenile survival of more than 40% from the 1970s until today. Furthermore, from 1974 to 2014, adult survival probability shows a consistently decreasing trend (− 0.26% year−1). We estimate the recovery probability for dead Red Kites in the first year (as juveniles) to be two times lower than that for birds that reach subadult/adult age. Also, the recovery probabilities of all age classes show a decreasing trend over time except for the last years. The spatial and temporal distributions of juvenile Red Kite recoveries suggest an increase in mortality at the breeding grounds, but in > 60% of cases the cause of death is unknown. The age-structured differences in recovery probability potentially highlight differences in the most important causes of mortality; however, further investigation of the cause of death in all ages classes is required to gain a more accurate picture. Our study provides valuable data for a better understanding of Red Kite demography and ongoing changes in population size.

Sympatric wintering of Red Kites and Black Kites in south-east Europe

We characterized the spatiotemporal activities in winter grounds of Red Kites originated from central Europe and wintering in south-eastern Europe. We found not only Red Kites at these places but often also Black Kites Milvus migrans. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161 ± 43 SD, n = 14 cases). We usually found a number of Red Kites wintering together at winter grounds, although some Red Kites wintered alone. We found Black Kites wintering together with Red Kites at the same winter grounds in 6 out of 14 cases. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the numbers of Black Kites were lower than the numbers of Red Kites or Black Kites were wholly absent. If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for birds staying at one place through the entire winter was from 10 to 108 km2 (median 72, mean 60 ± 36 SD, n = 12 cases) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km2 (median 434, mean 466 ± 115 SD, n = 3 cases) which is substantially larger than the size of home ranges published to date for Red Kites wintering in central and south-western Europe.

Entrevista com Mark Fellowes: "We must learn to reduce our demands on the ecosphere, but I'm not sure that we're smart enough to do that" 26-29

Dr. Mark Fellowes studied Zoology at Imperial College London (1995) and moved to Imperial’s Silwood Park campus to complete a Ph.D. in Evolutionary Biology (1998), followed by a brief post-doctoral position at the NERC Centre for Population Biology. He joined the University of Reading as a lecturer in Zoology (2000). Dr. Fellowes’ group work on human-wildlife interactions (People and Wildlife Research Group), asking how the choices people make have unforeseen consequences for species. Current projects include work on red kites, urban greening, cats and conservation, leopard ecology and urban butterfly population dynamics, and how the presence of mutualists affects plant-herbivore-enemy interactions in an urban context. The work of Dr. Fellowes’ research group has featured widely in national and international print and broadcast media, won a silver medal at the Chelsea Flower Show, and he has published two science books aimed at the general public

The Honey-Buzzards of the Sensebezirk: First Findings on Density, Diet, Reproduction and Food Competition in a Swiss Population of Honey-Buzzard Pernis Apivorus

In 2018 a nest of Honey-buzzard Pernis apivorus was found during a research project on Red kites Milvus milvus in Switzerland in an area where the cantons of Bern and Fribourg border. The diet was analysed by using a camera trap at the nest. In 2019 I started a private project to get an insight in Honey-buzzard density and reproduction in the area. 1)Territory density and reproduction: In 2018 one nest was found occasionally where two chicks fledged. In 2019, 8 territories were mapped in 54.3 hours of observing at high viewpoints, covering ca. 100 km2. At 7 territories the reproduction could be determined with a moderate certainty, resulting in only one successful territory where one young was raised. 2)Diet: By following nests with camera traps, diet was determined by number of prey items brought to the nest per adult. Two successful nests were followed, one in 2018 and one in 2019 during the chick rearing phase. Common wasp Vespula vulgaris and grey coloured combs, presumably dominated by European wasp Vespula germanica formed the most frequently delivered prey to both nests, but the share of the overall prey was bigger on the nest of 2018 than on the nest of 2019, resp. 68,9% and 60,1%. Also, the mean size of the combs per aforementioned wasp species was bigger in 2018 than in 2019. In 2019 more alternative prey were brought to the nest, like Hornet Vespa crabro, Bumblebee Apinae and one Vole Arvicolinae. 3)Wasp predation: Predation on social wasps was followed with camera traps at occasionally found wasp nests, three in 2018 and one in 2019. Honey-buzzards appeared in front of the camera at two of the three nests found in 2018, 5 individuals, but none started digging nor harvested from the nests. Badger Meles meles, Polecat Mustela putorius, Red fox Vulpus vulpus, and Pine marten Martes martes were recorded showing interest without predating on the nests. The single nest found in 2019 was predated completely by a Pine marten Martes martes.

Status of the Red Kite Milvus milvus in Croatia, based on telemetry research: spatiotemporal distribution and new breeding record

Status of the Red Kite Milvus milvus in Croatia, based on telemetry research: spatiotemporal distribution and new breeding record

Occurrence of Red Kites Milvus milvus in Serbia based on birds tracked by telemetry devices

Abstract A total of 13 Red Kites Milvus milvus fitted with GPS/GSM telemetry loggers in central Europe were tracked in Serbia from 10 July 2014 until 31 March 2018. These birds remained in Serbia for 138 days (counted as number of one bird/one day stays). Red Kites occurred mostly in the Vojvodina Province (NW Serbia). They were registered most often in April and October, which corresponded to their spring and autumn migrations. It is possible that Red Kites occur in Serbia more often than formerly, and this could in future result in this threatened European raptor’s more frequently wintering and breeding within the country.

Urbanization and cattle density are determinants in the exposure to anticoagulant rodenticides of non-target wildlife

The persistence and toxicity of second generation anticoagulant rodenticides (SGARs) in animal tissues make these compounds dangerous by biomagnification in predatory species. Here we studied the levels of SGARs in non-target species of wildlife and the environmental factors that influence such exposure. Liver samples of terrestrial vertebrates (n = 244) found dead between 2007 and 2016 in the region of Aragón (NE Spain) were analysed. The presence of SGARs was statistically analysed with binary or ordinal logistic models to study the effect of habitat characteristics including human population density, percentage of urban surface, livestock densities and surface of different types of crops. SGARs residues were detected in 83 (34%) of the animals and levels >200 ng/g were found in common raven (67%), red fox (50%), red kite (38%), Eurasian eagle-owl (25%), stone marten (23%), Eurasian buzzard (17%), northern marsh harrier (17%), and Eurasian badger (14%). The spatial analysis revealed that the presence of SGARs residues in wildlife was more associated with the use of these products as biocides in urban areas and cattle farms rather than as plant protection products in agricultural fields. This information permits to identify potential habitats where SGARs may pose a risk for predatory birds and mammals.

Acute and Chronic Lead Exposure in Four Avian Scavenger Species in Switzerland.

Despite irrefutable evidence of its negative impact on animal behaviour and physiology, lethal and sublethal lead poisoning of wildlife is still persistent and widespread. For scavenging birds, ingestion of ammunition, or fragments thereof, is the major exposure route. In this study, we examined the occurrence of lead in four avian scavengers of Switzerland and how it differs between species, regions, and age of the bird. We measured lead concentration in liver and bone of the two main alpine avian scavengers (golden eagle Aquila chrysaetos and bearded vulture Gypaetus barbatus) over the entire area of the Swiss Alps and two of the main avian scavengers occurring in the lowlands of Switzerland (red kite Milvus milvus and common raven Corvus corax). Of those four species, only the bearded vulture is an obligate scavenger. We found that lead burdens in the two alpine avian scavengers were higher than those found for the same species elsewhere in Europe or North America and reached levels compatible with acute poisoning, whereas lead burdens of the two lowland avian scavengers seemed to be lower. Several golden eagles, but only one red kite with abnormally high bone lead concentrations were found. In all four species, a substantial proportion of birds had elevated levels which presumably represent recent (liver lead levels) or past (bone lead levels) uptake of sublethal doses of lead.

Prevalence and genotyping of Trichomonas infections in wild birds in central Germany.

Avian trichomonosis is a widespread disease in columbids and other birds, caused by ingestion of the unicellular flagellate Trichomonas gallinae which proliferate primarily in the upper respiratory tracts. Studies using genetic analyses have determined some highly pathogenic lineages in birds, but the prevalence and distribution of potentially pathogenic and non-pathogenic T. gallinae lineages in wild birds is still not well known. We examined 440 oral swab samples of 35 bird species collected between 2015 and 2017 in Hesse, central Germany, for Trichomonas spp. infection and for determining the genetic lineages. Of these birds, 152 individuals were caught in the wild and 288 individuals were admitted from the wild to a veterinary clinic. The overall Trichomonas spp. prevalence was 35.6%. We observed significant differences between bird orders, with the highest prevalence in owls (58%) and columbids (50%), while other orders had slightly lower prevalences, with 36% in Accipitriformes, 28% in Falconiformes and 28% in Passeriformes. Among 71 successfully sequenced samples, we found 13 different haplotypes, including two previously described common lineages A/B (20 samples) and C/V/N (36 samples). The lineage A/B has been described as pathogenic, causing lesions and mortality in columbids, raptors and finches. This lineage was found in 11 of the 35 species, including columbids (feral pigeon, woodpigeon, stock dove), passerines (greenfinch, chaffinch, blackbird) and raptors (common kestrel, sparrowhawk, red kite, peregrine falcon and common buzzard). One new lineage (R) was found in a sample of a chaffinch. In conclusion, we found that the prevalence of Trichomonas spp. infection in wild birds was high overall, and the potentially pathogenic lineage A/B was widespread. Our findings are worrying, as epidemic outbreaks of trichomonosis have already been observed in Germany in several years and can have severe negative effects on bird populations. This disease may add to the multiple pressures that birds face in areas under high land-use intensity.

Anesthetic Action and "Quantum Consciousness": A Match Made in Olive Oil.

Anesthetic Action and "Quantum Consciousness": A Match Made in Olive Oil.

Influence of persistent organic pollutants on the endocrine stress response in free-living and captive red kites (Milvus milvus)

Persistent organic pollutants (POPs) have the potential to impair the endocrine regulation of organisms and alter their ability to respond to environmental changes. We studied whether polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) affected the endocrine regulation of free-living and captive red kites (Milvus milvus) through studying the dynamics of corticosterone (CORT) and dehydroepiandrosterone (DHEA). We sampled migratory free-living kites coming from northern Europe and captive kites born in a rehabilitation center in Spain. We used body feathers from the interscapular region as a minimally-invasive and integrative matrix. The most abundant compound detected in free-living kites was 4,4′-dichlorodiphenyldichloroethylene (4,4′-DDE; 6.10 ± 1.56 ng g−1 dw feather) followed by CB-153 (3.10 ± 0.63 ng g−1 dw feather) and CB-180 (2.43 ± 1.08 ng g−1 dw feather). In captive kites, the most abundant compounds were 4,4′-dichlorodyphenyltrichloroethane (4,4′-DDT; 2.38 ± 1.30 ng g−1 dw feather), CB-153 (2.15 ± 0.47 ng g−1 dw feather) and hexachlorobenzene (HCB; 2.03 ± 0.45 ng g−1 dw feather) at similar concentrations. Free-living kites showed higher levels of 4,4′-DDE and CB-180 in comparison to captive kites. Age influenced HCB and CB-101 levels, whereas body mass was inversely related to CB-180 and 4,4′-DDT. Interestingly, captive kites showed a ratio DDT/DDE higher than 1 suggesting a relatively recent exposure of DDT, in contrast to free-living kites. Regarding hormonal levels, free-living kites showed higher levels of CORT (3.30 ± 0.22 pg mm−1 feather) than captive (2.40 ± 0.16 pg mm−1 feather), reflecting higher allostatic load. In addition, a positive association between PCBs and DDTs and adrenal hormones was found in free-living kites, suggesting an increase of CORT as a response of the endocrine system to cope with stressors and a subsequent elevation of DHEA to ameliorate the potential negative effects that high CORT levels could cause to the organism.