The internal temperature of nests largely depends on the materials used in their construction because the characteristics of each material affect the isolation of nest walls. In urban environments, the availability of natural materials for nest building decreases, while the availability of artificial materials increases. Therefore, many urban bird species use more artificial materials for nest building inside cities, which may affect the thermal properties of the nest. We conducted an experiment to measure the effect of artificial materials included as part of the nest structure, on nest thermoregulation. We used as a model, nests of the clay-colored thrush (Turdus grayi), an urban bird species that have been reported using artificial nest materials. In our experiment, we measured how variation in artificial materials mass affects the nest cooling rate in a climate-controlled room. We found that artificial materials increased the cooling rate of clay-colored thrush nests, compared with nests with only natural materials. This result is especially relevant because showed a negative direct effect of the use of artificial material for nest building in birds. Considering that the availability of artificial material is increasing in urban areas, while natural material is decreasing, it is expected that the negative effect of using artificital material for nest construction would increase in the clay-colored thrush and other city bird species.

Piscivorous avian species may be affected by mercury (Hg) which tends to accumulate in aquatic environments and biomagnifies across the food webs. One of such species is the black stork, whose population increase recently slowed down due to unknown reasons. At the same time Hg contamination and its effects were almost unaudited for this species, so it may have exerted deleterious effects on the population and an evaluation is necessary. This is the first study of this species concerning Hg contamination. Thus, Hg concentrations were investigated in the down of black stork chicks (N = 90) from breeding locations in central and southern Poland (Europe) between 2015 and 2017. As well as Hg levels, morphometric parameters and age were evaluated. Mean Hg concentrations reached 0.7 μg/g d.w. and differed significantly between years, from the lowest value noted in 2017 (mean 0.5 μg/g), through 2016 (0.7 μg/g), to the highest one in 2015 (0.9 μg/g), and between nest locations where higher Hg levels were generally found in northern parts of the study area. Hg concentrations were also unrelated to morphometric parameters. Contrarily, morphometric parameters revealed high correlations between themselves, which was confirmed by the cluster analysis (revealing only two clusters) and principal component analysis (the first PC explained 96.8% of the variance). Hg levels in the down of black storks were rather low with the fluctuation between years and nest locations probably caused by parental exposure during wintering, migration, pre-breeding season and recent exposure through food provided by parents. Such low Hg concentrations seemed not to affect the population from the region studied.

Evidence is accumulating about the impacts of plastics on marine life. The prevalence of plastics in seabird nests has been used as an indicator of levels of this pollutant in the ocean. However, the lack of a framework for defining sample sizes and errors associated with estimating the prevalence of plastic in nests prevents researchers from optimising time and reducing impacts of fieldwork. We present a method to determine the confidence intervals for the prevalence of debris in seabird nests and provide, for the first time, information on the prevalence of these items in nests of the Hartlaub’s gull Larus hartlaubii, the African penguin Spheniscus demersus, the great white pelican Pelecanus onocrotalus, and the white-breasted cormorant Phalacrocorax lucidus in South Africa. The method, based on observations and resampling simulations and tested here for nests of 12 seabird species from 15 locations worldwide, allows for straightforward hypothesis testing. Appropriate sample sizes can be defined by combining this method with a Bayesian approach. We show that precise estimates of prevalence of debris in nests can be obtained by sampling around 250 nests. Smaller sample sizes can be useful for obtaining rough estimates. For the Hartlaub’s gull, the African penguin, the great white pelican, and the white-breasted cormorant, debris were present in 0.75%, 3.00%, 6.41%, and 25.62% of the respective nests. Our approach will help researchers to determine errors associated with the prevalence of debris recorded in seabird nests and to optimise time and costs spent collecting data. It can also be applied to estimate confidence intervals and define sample sizes for assessing prevalence of plastic ingestion by any organism.

We monitor pollutant accumulation and investigate associated changes at the physiological level within the population of an obligate avian scavenger, the Egyptian Vulture (Neophron percnopterus), from Catalonia (NE Spain). This population is expanding its range, presumably because of the use of human waste disposal sites as food resource. We hypothesized that habitat urbanization, presumably associated with feeding from human wastes, could influence the accumulation of persistent organic pollutants and metals. The aim of this study was to explore the relationship between accumulated pollutants and biochemical parameters in nestling blood. We used the proportion of urban surface within an 8 km radius of each nest as a proxy to study the relationship between anthropic influence and pollutant accumulation. Observed blood levels of metals, organochlorine pesticides, polychlorinated biphenyls (PCBs), per- and polyfluoroalkylated substances (PFAS) and polybrominated diphenyl ethers (PBDEs) were relatively low, as expected for nestling individuals due to short-term exposures. CB-180 and PBDEs were associated with variations in blood biochemistry parameters; hexa-BDEs appeared positively associated with activities of the enzymes aspartate aminotransferase and lactate dehydrogenase, whereas CB-180 accumulation was associated with an increased activity of creatine phosphokinase and elevated glutathione levels. Increased CB-180 levels were also related to decreased blood concentrations of calcium, cholesterol, α-tocopherol and lutein. A proportion of urban surfaces as low as 6.56% within a radius of 8 km around the nest appears related to the accumulation of CB-180, the majority of analysed PFAS and of PBDE congeners 99 and 209, and increased urbanization was also associated with decreased plasma levels of α-tocopherol and carotenoids. These associations suggest that changes in blood profiles of vitamins, carotenoids or other analytes, despite related to increased plasma levels of CB-180, would be consequence of exploitation of artificial food sources rather than of a direct effect of the pollutants.

Mercury pollution is currently a major public health concern, given the adverse effects of mercury on wildlife and humans. Soil plays an essential role in speciation of mercury and its global cycling, while being a habitat for a wide range of terrestrial fauna. Soil fauna, primarily soil-feeding taxa that are in intimate contact with soil pollutants are key contributors in the cycling of soil mercury and might provide relevant indications about soil pollution. We studied the enrichment of various mercury species in the nests and bodies of soil-feeding termites Silvestritermes spp. in French Guiana. Soil-feeding termites are the only social insects using soil as both shelter and food and are major decomposers of organic matter in neotropical forests. Nests of S. minutus were depleted in total and mobile mercury compared to nearby soil. In contrast, they were enriched 17 times in methylmercury. The highest concentrations of methylmercury were found in body of both studied termite species, with mean bioconcentration factors of 58 for S. minutus and 179 for S. holmgreni relative to the soil. The assessment of the body distribution of methylmercury in S. minutus showed concentrations of 221 ng g⁻¹ for the guts and even higher for the gut-free carcasses (683 ng g⁻¹), suggesting that methylmercury is not confined to the gut where it was likely produced, but rather stored in various tissues. This enrichment in the most toxic form of Hg in termites may be of concern on termite predators and the higher levels in the food chain that may be endangered through prey-to-predator transfers and bioaccumulation. Soil-feeding termites appear to be promising candidates as bio-indicators of mercury pollution in soils of neotropical rainforest ecosystems.

Ants accumulate heavy metals and respond to pollution with modification in species composition, community structure, altered behaviour and immunity. However, the levels of heavy metals in ants’ nests and explicit individual-level responses towards heavy metals have not been revealed. We found that red wood ants Formica lugubris accumulate high and correlated values of such heavy metals as Al, Cd, Co, Cu, Fe, Ni, Pb and Zn both in ants and nest material near cobalt smelter in Finland. Relative differences in metal concentrations were higher in nests than in ants. The highest values were obtained for elements such as Co (36.6), Zn (14.9), Cd (9.7), Pb (8.5), Cu (7.4), Ni (6.4), As (4.7), Cr (2.9) and Fe (2.4) in nest material, and Co (32.7), Cd (6.3), Pb (6), Fe (2.8), Ni (2.9) and Zn (2.1) in ants. In industrial and reference areas, ants have no differences in size, but differed in dry and residual body mass. In polluted areas, F. lugubris had less melanised heads, but not thoraxes. The sensitivity of cuticular colouration in red wood ants subjected to heavy metal pollution might be related to metal-binding properties of melanins. The overall results are useful for the improvement of biomonitoring techniques using ants as indicators of industrial contamination and for further discovery of novel ecotoxicological biomarkers.

We studied indices of reproductive outcome in three aquatic species in relation to organochlorine concentrations during four decades. In female otters, the frequency of signs of reproduction increased after 1990. In grey seals, pregnancy rate increased 1990–2010 and uterine obstructions ceased after 1993. The frequency of uterine tumours was highest 1980–2000. The number of sea eagle nestlings per checked nest increased 1985–2000, while the frequency of desiccated eggs decreased. Organochlorine concentrations decreased at annual rates between 3.5 and 10.2%. The estimated mean concentration (mg/kg lw) for total-PCB decreased from 70 to 8 (otters), from 110 to 15 (seals) and from 955 to 275 (eagles). The corresponding concentrations for ΣDDT decreased from 3.4 to 0.2 (otters), from 192 to 2.8 (seals) and from 865 to 65 (eagles). This study adds evidence to support the hypothesis that PCBs and DDTs have had strong negative effects on the reproduction and population levels of these species.

Human pressure exerts a significant influence on animals and the environment. One of its consequences, plastic pollution is considered one of the major threats to fauna as well as a significant conservation issue. In this research, we examined the global pattern of one example of avian behavior in response to pollution—namely, the incorporation of anthropogenic materials into nests—as well as the existing knowledge on this subject. Based on 25 articles, we studied 51 populations, involving 24 bird species, and checked 10,790 nests; as a result, we found that incorporation of debris is correlated with increasing human influence on the environment, measured as the Human Footprint Index. Moreover, the probability of debris incorporation is higher in terrestrial than in marine species. We also identified knowledge bias in favor of marine as opposed to terrestrial species: namely, marine species attract more scientific attention than terrestrial. Furthermore, research approaches to these two ecosystems differ. Undeniably, the factors which influence debris incorporation by birds, the scale of this behavior, and particular forms of use of debris in bird nests are aspects which require long-term standardized research. This is the first global review paper on debris incorporation by birds to demonstrate a close link to human pressure as a driver.

Venlafaxine is an antidepressant and anti-anxiety drug that has been detected in municipal wastewater at low μg/L concentrations. In this study, the nest-defense behavior of adult male fathead minnows (Pimephales promelas) was observed in fish exposed for a full lifecycle to venlafaxine nominal concentrations of 0.88, 8.8, and 88 μg/L (i.e. 1, 9.3, 75 μg/L mean measured concentrations). Nest-defense behaviors quantified were the time taken to contact a dummy intruder fish (on a flexible stick, held near each nest) and the number of contacts made during a 1 min period. In male fathead minnows exposed to venlafaxine over a full lifecycle at environmentally relevant nominal concentrations (i.e. 0.88 and 8.8 μg/L) no significant effects were observed in behavior. However, in males exposed over a full lifecycle to the highest concentration of venlafaxine (i.e. 88 μg/L), nest-defense behaviors were increased in males with empty nests, as shown by the significantly elevated percentage of empty-nest males that made contact with the dummy intruder fish (89%) relative to the lower percentage of contacts (65%) among the Control males (p = 0.046). Lifecycle exposure to high venlafaxine (88 μg/L) caused males to over-protect their empty nests. Environmental venlafaxine concentrations are approximately 70 x lower than this, so it is unlikely that behavioral changes from venlafaxine exposure would occur in the environment. Normal nest defense behaviours in control males varied, depending on whether they were protecting empty nests or nests with eggs. Compared to Control males with empty nests, more Control males with eggs in their nests made contact with the dummy intruder fish (p = 0.014), contact was faster (i.e. <10 s, p = 0.011), and they hit the dummy intruder fish more times in 1 min (p = 0.031) This study is the first to assess reproductive behaviors in fish exposed to an antidepressant over a full lifecycle.

The selenium contamination event that occurred at Kesterson Reservoir (Merced Co., CA) during the 1970–80s is a frequently cited example for the negative effects of contamination on wildlife. Despite the importance of arthropods for ecosystem services and functioning, relatively little information is available as to the impacts of pollution on arthropod community dynamics. We conducted surveys of the arthropod community present at Kesterson Reservoir to assess the impacts of selenium contamination on arthropod diversity, with a focus on ant species richness, composition and density. Trophic groups were compared to determine which arthropods were potentially receiving the greatest selenium exposure. Plant samples were analyzed to determine the selenium content by site and by location within plant. Soil concentrations varied across the study sites, but not across habitat types. Topsoil contained higher levels of selenium compared to core samples. Plants contained similar concentrations of selenium in their leaves, stems and flowers, but flowers contained the greatest range of concentrations. Individuals within the detritivores/decomposers and predators accumulated the greatest concentrations of selenium, whereas nectarivores contained the lowest concentrations. Species composition differed across the sites: Dorymyrmex bicolor was located only at the site containing the greatest soil selenium concentration, but Solenopsis xyloni was found at most sites and was predominant at six of the sites. Selenium concentrations in ants varied by species and collection sites. Nest density was also found to differ across sites, but was not related to soil selenium or any of the habitat variables measured in our study. Selenium was not found to impact species richness, but was a significant variable for the occurrence of two out of the eight native species identified.