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Measuring corticosterone concentrations in feathers (FCC) has been increasingly used as an integrated index of bird's response to stressors, offering valuable insights into subsequent carry-over effects. However, it is still unclear to what extent corticosterone levels deposited in feathers during the moulting period relate to individual physiology in high-energetic demanding situations. In addition, the stability and repeatability of FCC over the same feather generation and across successive generations are still unresolved questions. In this study, we assessed FCC in 24 captive Northern Bald Ibis, Geronticus eremita. We sampled body feathers on three occasions during two consecutive years (2015–2016) to explore within-individual stability of FCC in feathers grown during the same generation and test whether FCC was repeatable or varied between two consecutive generations. Then, we explored whether FCC (a) was associated with individual health status, (b) correlated with previous reproductive success and (c) was related to future reproductive success. Results showed high stability of FCC among feathers of the same generation, while FCC differed between successive generations. We also observed that FCC, age and health status were negatively associated with subsequent reproductive success the following season, while no association was found with previous reproductive success. Overall, our study supports the use of feathers as a stable measure of corticosterone over the same feather replacement generation and emphasizes the usefulness of FCC as a biomarker of subsequent reproductive success. [ABSTRACT FROM AUTHOR]

Abstract 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. Graphical abstract Unlabelled Image Highlights • Assessment of POPs and OPEs in down feathers of nestling cinereous vultures • Exploration of the relationship between POPs and OPEs and the HPA axis response • The most persistent POPs, but not OPEs, are positively related to corticosterone levels. • High POP and corticosterone levels do not impact nestling growth. • Late egg-laying relates to high corticosterone levels and reduced nestling period. [ABSTRACT FROM AUTHOR]

The occurrence of organohalogenated compounds (OHCs) in wildlife has received considerable attention over the last decades. Among the matrices used for OHCs biomonitoring, feathers are particularly useful as they can be collected in a minimally or non-invasive manner. In this study, concentrations of various legacy OHCs –polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)–, as well as emerging OHCs –per- and polyfluoroalkyl substances (PFAS) and organophosphate ester flame retardants (OPEs)– were determined in feathers of 72 Eurasian eagle-owls (Bubo bubo) from Norway, with the goal of studying spatiotemporal variation using a non-invasive approach. Molted feathers were collected at nest sites from northern, central and southern Norway across four summers (2013–2016). Additionally, two museum-archived feathers from 1979 to 1989 were included. Stable carbon (δ13C) and nitrogen isotopes (δ15N) were used as dietary proxies. In total, 11 PFAS (sum range 8.25–215.90 ng g−1), 15 PCBs (4.19–430.01 ng g−1), 6 OCPs (1.48–220.94 ng g−1), 5 PBDEs (0.21–5.32 ng g−1) and 3 OPEs (4.49–222.21 ng g−1) were quantified. While we observed large variation in the values of both stable isotopes, suggesting a diverse diet of the eagle-owls, only δ13C seemed to explain variation in PFAS concentrations. Geographic area and year were influential factors for δ15N and δ13C. Considerable spatial variation was observed in PFAS levels, with the southern area showing higher levels compared to northern and central Norway. For the rest of OHCs, we observed between-year variations; sum concentrations of PCBs, OCPs, PBDEs and OPEs reached a maximum in 2015 and 2016. Concentrations from 1979 to 1989 were within the ranges observed between 2013 and 2016. Overall, our data indicate high levels of legacy and emerging OHCs in a top predator in Norway, further highlighting the risk posed by OHCs to wildlife. • Assessment of legacy and emerging OHCs in feathers of Norwegian eagle-owls. • Exploration of spatiotemporal variations and association with dietary proxies. • High concentrations of both legacy and emerging OHCs are found. • Spatial variation is observed for PFAS, while POPs and OPEs show between-year variation. [ABSTRACT FROM AUTHOR]

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. Unlabelled Image • We reviewed 114 studies on lead contamination in European raptors. • We found a lack of homogenization in the monitoring schemes around Europe. • Lead concentrations varied across feeding traits and between sampling seasons. • Evidence for high occurrence of lead contamination was found, especially in scavengers. • We urge studies relating lead exposure to quantitative impacts on European raptors. [ABSTRACT FROM AUTHOR]

The analysis of corticosterone (CORT), the main glucocorticoid in reptiles, via blood or faeces provides an index of hormone concentrations over a relatively short time period. Unlike these conventional matrices, snake shed skin is supposed to incorporate circulating CORT over the period of skin growth, thus reflecting long-term retrospective levels of the hormone. The present study aimed to assess the feasibility to extract CORT from shed skin of Komodo dragon and biochemically validate the quantification of the hormone by enzyme immunoassay (EIA). Additionally, possible sources of variation in shed skin CORT that could reflect biological variation were examined (sex, age, body region and season of ecdysis). Results of the biochemical validation showed that CORT can be reliably measured in shed skin of Komodo dragon by EIA through the presented methodology. Males presented statistically higher levels of CORT than females, and when accounting for males' seasonal differences, concentrations decreased significantly from spring to summer. Juveniles showed higher CORT values than adults, however, results should be interpreted with caution since the model revealed that date of ecdysis was significantly influencing CORT levels. Besides that, concentrations of CORT were not influenced by body region. Overall, the present study demonstrates a potential biological source of variation in shed skin CORT concentrations due to sex, age and season of skin ecdysis. Combined with other indicators, detection of CORT concentrations in shed skin could allow a systematic control of Komodo dragon's physiology, offering a useful tool for zoo management and providing key data for the species conservation. [ABSTRACT FROM AUTHOR]

The article offers information on the ubiquity of plastics pollution and its effects on ecosystems throughout the plastics life cycle. Topics include the environmental impact of plastic manufacturing; the entanglement and choking of wildlife; and the concentration of pollutants in plastic industry.

Abstract: Life history theory states that individual fitness in one stage of life is conditioned by what occurred in previous stages. In migratory species, reproductive effort during breeding has often been found to influence body condition, molt schedule, self‐provisioning and migration of individuals in subsequent seasons (i.e., carryover effects of breeding). However, there is a current uncertainty in understanding how long‐distance migrants trade off among such energy‐demanding activities (i.e., breeding, molting and migrating). To provide evidence to the field, we experimentally reduced the parental effort of a long‐lived Procellariform, the Cory's shearwater (Calonectris borealis), by inducing failure at the incubation stage. Treatment and control birds were tracked during their subsequent migration by means of light‐level and immersion loggers and sampled for six specific feathers (molted at different periods along the migratory cycle) upon the recovery of the loggers 1 yr later. Feathers were used to perform stable isotope analysis (SIA) and determine corticosterone levels (CORT). By these means, we evaluated the effect of breeding effort on migratory strategy, at‐sea activity patterns, molt patterns, and levels of stress experienced by birds along the non‐breeding period. We did not detect any difference between birds in the induced failure group and successful breeders in terms of spatio‐temporal distribution: all birds shared common foraging areas throughout the study period and the timing of major phenological events did not differ. Failed birds significantly advanced their molt, as revealed by SIA and flying activity patterns. The stress levels of failed birds, inferred through CORT concentrations in feathers, were found to be consistently lower than in successful breeders, through the end of the breeding to the non‐breeding period. Thus, we provide robust evidence that the costs of reproduction can be physiologically mediated from the breeding to the non‐breeding period through molting schedules and CORT levels. However, we failed to detect clear effects on migratory behavior or subsequent breeding success, suggesting that costs of breeding in long‐lived species may be rapidly buffered during the post‐breeding period, as would be expected from life history theory. [ABSTRACT FROM AUTHOR]

Concentrations of different steroid hormones have been used in cows as a measure of adrenal or gonadal activity and, thus, as indicators of stress or reproductive state. Detecting cortisol and progesterone in cow hair provides a long-term integrative value of retrospective adrenal or gonadal/placental activity, respectively. Current techniques for steroid detection require a hormone-extraction procedure that involves time, several types of equipment, management of reagents, and some assay procedures (which can also be time-consuming and can destroy the samples). In contrast, near-infrared reflectance spectroscopy (NIRS) is a multi-component predictor technique, characterized as rapid, nondestructive for the sample, and reagent-free. However, as a predictor technique, NIRS needs to be calibrated and validated for each matrix, hormone, and species. The main objective of this study was to evaluate the predictive value of the NIRS technique for hair cortisol and progesterone quantification in cows by using specific enzyme immunoassay as a reference method. Hair samples from 52 adult Friesian lactating cows from a commercial dairy farm were used. Reflectance spectra of hair samples were determined with a NIR reflectance spectrophotometer before and after trimming them. Although similar results were obtained, a slightly better relationship between the reference data and NIRS predicted values was found using trimmed samples. Near infrared reflectance spectroscopy demonstrated its ability to predict cortisol and progesterone concentrations with certain accuracy (R²=0.90 for cortisol and R²=0.87 for progesterone). Although NIRS is far from being a complete alternative to current methodologies, the proposed equations can offer screening capability. Considering the advantages of both fields, our results open the possibility for future work on the combination of hair steroid measurement and NIRS methodology. [ABSTRACT FROM AUTHOR]