The reproductive success and quality of blue tits (Parus caeruleus) in a heavy metal pollution gradient

Stochastic processes shape the functional and phylogenetic structure of bird assemblages at the mine area in southwest China

Understanding the mechanisms of community assembly is a key question in ecology. Metal pollution may result in significant changes in bird community structure and diversity, with implications for ecosystem processes and function. However, the relative importance of these processes in shaping the bird community at the polluted area is still not clear. Here, we explored bird species richness, functional, and phylogenetic diversity, and the assembly processes of community at the mine region of southwest China. Our results showed that the 3 dimensions of diversity at the mine area were lower than that at the reference sites. In the community assembly, the result was 0 < NRI/ NFRI < 1.96, which indicated deterministic processes (environmental filtering) might drive community clustering. The results of the neutral community model, and normalized stochasticity ratio, showed the dominant role of stochastic processes in shaping the bird community assembly. We further quantified the community-level habitat niche breadth (Bcom), and we found that there was no difference in Bcom-value between the mine area and reference sites. This indicates that the bird communities at the mine area and 3 reference sites were not subjected to extreme environmental selection (same or different resource allocation) to form a highly specialized niche. These findings provide insights into the distribution patterns and dominant ecological processes of bird communities under metal exposure, and extend the knowledge in community assembly mechanisms of bird communities living in the mine area.

Untangling behaviours: independent expressions of female-female aggression and snake-like hissing in the blue tit (Cyanistes caeruleus)

Aggression plays a crucial role in deterring predators and securing resources to promote fitness. Nevertheless, studies focussing on female aggression remain scarce. In songbirds, aggression is prevalent during the breeding season, when same-sex individuals compete for limited resources. Additionally, females of some bird species exhibit snake-like hissing behaviour during incubation presumably to lower predation rates and improve fitness. Such behaviours may co-vary, forming a behavioural syndrome that could constrain trait expression. Here, we investigated a resident population of blue tits (Cyanistes caeruleus), to examine the repeatability and covariation of female-female aggression and hissing behaviour, aiming to determine if these constitute a behavioural syndrome. We quantified female-female aggression during simulated territorial intrusions and measured number of hissing calls in response to a simulated predator intrusion into the nest box. We found that both female-female aggression and hissing behaviour were repeatable traits, and that older females approached the intruder less. However, we found no evidence of covariation between female-female aggression and hissing behaviour. Thus, our findings suggest that female-female aggression and hissing behaviour, although both displayed in a nest defence context, are evolutionarily independent traits in the blue tit.

Females Are More Aggressive Than Males towards Same- and Opposite-Sex Intruders in the Blue Tit (Cyanistes caeruleus)

During the breeding season, aggression is expressed to gain access to resources such as territories and mates and protect offspring. Female aggressiveness has received much less attention than male aggressiveness, and few studies have examined female and male aggressiveness towards intruders of both sexes in the same species. We compared female and male aggressiveness towards same- and opposite-sex intruders during the egg-laying period in blue tits (Cyanistes caeruleus) using simulated territorial intrusions. For each sex, we examined the occurrence of different behavioural responses during agonistic encounters, and compared the intensity and individual consistency of intra- and inter-sexual aggression using same- and opposite-sex taxidermy mounts. Our results show that females are the more aggressive sex. Both sexes showed similar behaviours during simulated intrusions, although females were never observed singing and males never entered the nest box. In females, aggression was predominantly independent of the sex of the intruder, while males sang more from a distance during male-male encounters. The relative levels of aggression (pecking and perching on the mounts) during intra- and intersexual conflicts were consistent for females, but not for males. Females might be under stronger selection for aggressive phenotypes due to nest-hole competition and larger reproductive investments.

A multi-tissue biomonitoring investigation of toxic trace elements and their trophic transfer potential in a semi aquatic bird species, the Cattle Egret (Bubulcus ibis)

The constant exposure of toxic trace elements can elicit adverse health effects particularly in birds and species residing higher at the food web. The current study is designed to evaluate the tendency of toxic trace elements viz. Cd, Cr, Pb, Cu, As and Hg to bioaccumulate in liver, kidney, blood, pelvic and pectoral muscles of cattle egret (Bubulcus ibis) collected from premises of a metropolitan city, Lahore, Pakistan. Further, the Trophic Transfer Potential of these elements was also estimated using prey/food samples of cattle egret. All of the selected toxic trace elements except Hg and As were detected with varying concentrations in different tissues of cattle egret. In general, toxic trace elements followed the pattern as Cu > Pb > Cd > Cr in tissues of cattle egret. The maximum mean (Min-max) concentrations (μg/g) of Cu 0.58 (0.11-0.93) and Pb 0.46 (0.40-0.54) in blood and Cd at 0.46 (0.40-0.54) were observed in liver. Similarly, the highest mean (min-max) concentration (μg/g) of Cr 0.17 (0.09-0.25) was recorded in pectoral muscle. In general, blood and liver were found as the most contaminated tissues followed by kidney, pectoral and pelvic muscles. Differences of trace elements were found non-significant (all P > 0.05) among tissues of cattle egret reflecting their homogenous distribution in body. Principal Component Analysis (PCA) corroborated lack of strong association between any of the trace elements and tissues. All the toxic trace elements except Cr showed higher tendency of trophic transfer potential through food chain in all the tissues of Cattle Egret (TTF >1). Although the current study revealed decreasing trends of toxic trace elements, yet their still presence in the local environment and greater likelihood of trophic transfer can undoubtedly cause some severe health effects to the already declining bird populations.

Replicated, urban-driven exposure to metallic trace elements in two passerines

While there are increasing examples of phenotypic and genotypic differences between urban and non-urban populations of plants and animals, few studies identified the mechanisms explaining those dissimilarities. The characterization of the urban landscape, which can only be achieved by measuring variability in relevant environmental factors within and between cities, is a keystone prerequisite to understand the effects of urbanization on wildlife. Here, we measured variation in bird exposure to metal pollution within 8 replicated urbanization gradients and within 2 flagship bird species in urban evolutionary ecology: the blue tit (Cyanistes caeruleus) and the great tit (Parus major). We report on a highly significant, positive linear relationship between the magnitude of urbanization-inferred as either tree cover, impervious surface cover, or an urbanization score computed from several environmental variables, and copper, zinc and lead concentrations in bird feathers. The reverse relationship was measured in the case of mercury, while cadmium and arsenic did not vary in response to the urbanization level. This result, replicated across multiple cities and two passerine species, strongly suggests that copper, zinc, lead and mercury pollution is likely to trigger the emergence of parallel responses at the phenotypic and/or genotypic level between urban environments worldwide.

Assessment of Heavy Metal Contamination in Excreta of Baya Weaver Bird (Ploceus Philippinus) from Three Districts of Different Zones of Punjab

The objective of the study was to assess the heavy metal contamination in excreta of the Baya Weaver Bird (Ploceus philippinus). Samples were collected from nesting colony sites present in three districts viz. Ludhiana (location I), Ropar (location II) and Ferozepur (location III) falling in Central plain zone, Undulating plain zone and Western plain zone of Punjab respectively. In dry excreta samples fifteen elements were detected through ICAP-AES; As, Pb, Cd, Cr were toxic heavy metals and B, Fe, Cu, Ni, Zn, Mn, Mg, Ca, P, S, Na were essential elements. Toxic heavy metals viz. As (1.88-2.10 ppm), Pb (2.70- 5.25 ppm) and Cr (13.30-23.78 ppm) were found above normal range in excreta collected from studied locations. Statistical analysis showed significant difference among heavy metals and locations which signifies the bioaccumulation of different metals at different locations in excreta of Baya Weaver Bird due to different type of contaminations at studied locations.

Effects of environmental metal pollution on reproduction of a free-living resident songbird, the tree sparrow (Passer montanus)

Anthropogenic metal pollution is known to adversely affect bird reproduction; however, few systematic studies are available on the effects of metal pollution on breeding performance and parental investment in a common resident songbird, the tree sparrow (Passer montanus). We conducted this study in two sites, a long-term heavy metal polluted site (Baiyin [BY]) and a relatively unpolluted site at approximately 110 km distance (Liujiaxia [LJX]), to assess the potential effects of environmental metal contamination on breeding parameters (clutch size, hatching success, fledging success, and growth of nestlings) and parental investment. The results showed smaller clutch size, lower fledging success, and differences in incubation behaviors of tree sparrows in BY than in LJX. Although there was no difference in parental body condition (residual body mass) between the two study sites, the parents responded differently with respect to reproduction due to varying metal levels in their habitats and bodies. Higher Cd levels in the primary feathers of females in BY were associated with lower clutch sizes. Parental investment including incubation duration and feeding rates showed no significant difference between the two sites during the incubation and nestling periods, but the frequencies of incubation visits were higher in BY. Parental behavior during the incubation period was also negatively affected by the parental Pb and Cd levels. Although the nestling growth patterns were relatively similar between the two sites, the nestlings were smaller, had lower body weight, and fledged later and fledging rate was also lower in BY than in LJX. Metal concentrations were higher in nestling organs and feces in BY. Taken together, metal pollution might adversely affect nestling growth condition. Our results suggest a negative response in the reproduction of tree sparrows to long-term environmental metal pollution.

Assessment of heavy metals in different organs of cattle egrets (Bubulcus ibis) from a rural and urban environment in Pakistan

The study was conducted to evaluate the concentration of essential elements (Cu, Fe, Mn, Ni, Se, Zn, and B) and non-essential elements (Cd, Pb, Hg, Cr, As, and Ni) in muscle, liver, bone, and intestine of matured cattle egret (Bubulcus ibis). Sampling was carried out at two sites of Lahore, Pakistan-Havalian Karbath (site I) and Mehmood Booti (site II)-over a period of 1 month in the winter season. Metal analyses of samples were carried out using inductively coupled plasma mass spectroscopy (ICPMS). The trend of essential elements in liver and intestine of site I was noticed as Fe > Zn > Cu > B > Mn > Se > Ni and almost same for bone and muscle as Fe > Zn > B > Mn > Cu > Se > Ni. It was noticed that Cu was less deposited in bone and muscle tissues compared to liver and intestine from site I. The deposition of essential elements in liver and intestine from site II was noticed as Fe > Zn > Cu > Mn > B > Se > Ni. Similar trend was found for bone and muscle: Fe > Zn > B > Mn > Cu > Se > Ni with great deposition of B than Cu compared to liver and intestine. The findings of the present study revealed almost similar trend for essential elements deposition at both sites. However, a random trend was observed for deposition of non-essential elements (Ag, As, Ba, Cd, Cr, Hg, Pb) in organs from both sites. Moreover, data showed higher levels of non-essential elements accumulation (particularly As, Ba, and Pb) in the body tissues/organs of cattle egret in an urban area (site II) as compared to rural area (site I) of Lahore. Furthermore, non-essential elements were more in intestine, bone, and muscles from site II showing more exposure to some non-essential elements at urban site due to human and natural activities. However, higher concentration of non-essential elements in liver from site I as compared to other organs not only reflect the land exposure to plant growth promoting fertilizers and sewage water for irrigation purpose but also better detoxification abilities of the rural birds. The study gave a new insight to inform contamination levels in the rural and urban sites. Future implications of this study need remediation strategies to clean environment requisite for avian species.

Analysis of 11 trace elements in flight feathers of Italian Sparrows in southern Italy: A study of bioaccumulation through age classes, variability in three years of sampling, and relations with body condition

Trace elements have been acknowledged as one of the subtlest environmental hazards in all compartments of the total environment. Enhanced by activities in the anthroposphere, they accumulate in the atmosphere, lithosphere, and hydrosphere. Eventually, trace elements can bioaccumulate or biomagnifiy in the biosphere, with harmful effects on animals occupying higher trophic levels, including humans. Accordingly, there is great interest in assessing and monitoring trace element concentrations in the biosphere, and birds, especially passerines, have been commonly chosen as biomonitors. In this study, the concentration of 11 trace elements was measured (i.e. aluminum, chromium, manganese, iron, nickel, copper, zinc, arsenic, cadmium, barium, and lead) in flight feathers of Italian Sparrows, a common bird species hitherto not analysed in this respect. Samples were collected in an agricultural area in southern Italy, where a mosaic of natural environments, urbanized areas and industrial facilities can be found. Linear mixed modelling was applied to the analysis of flight feathers in juveniles, juvenile birds moulting to adulthood, and adults in three sampling years on 184 birds. Results are timely as they add new data to the scarce available information on Ba and As in bird feathers and showed clear bioaccumulation patterns from juveniles to adults for As, Cr, and Cd. Moreover, the modelling approach showed that the concentration of elements such as As, Cd and Cr can be variable across the years and that some elements, notably Cd and Ba, were inversely correlated with body mass and wing length, respectively, suggesting potential negative effects on bird health. Finally, when modelling bird body condition and trace elements, results showed that Cd and Ba negatively affect birds regardless of age or sampling year. Thus, the Italian Sparrow could be considered as a valuable biomonitor for trace elements in the total environment, especially for Cd and Ba.

Reproduction impairments in metal-polluted environments and parental hormones: No evidence for a causal association in an experimental study in breeding feral pigeons exposed to lead and zinc

Humans are responsible for land-cover changes resulting in the emission of hazardous chemical elements including metallic trace elements i.e. MTEs. As a consequence, urban wildlife is exposed to high concentrations of MTEs, which exposure is linked to reproductive impairments. MTE effects on reproduction outputs might result from MTE exposure disrupting the endocrine pathways involved in reproductive behaviours. In birds, there is strong evidence that prolactin, corticosterone and testosterone are all involved in the regulation of parental effort during incubation and chick rearing. Endocrine-disrupting chemicals might stimulate or inhibit the production of those hormones and consequently alter parental investment and reproductive success outcomes. We measured baseline corticosterone, prolactin and testosterone plasma levels, and the corticosterone stress response of breeding feral pigeons (Columba livia) experimentally exposed to ecologically relevant lead and/or zinc concentrations. Independently of lead and/or zinc exposure, male and female plasma levels of corticosterone and prolactin (but not testosterone) showed temporal variations along the reproduction stages (i.e. incubation, early rearing and late rearing). In addition, both hatching and fledging success were slightly correlated with corticosterone, prolactin and testosterone levels. However, our study did not find any influence of lead or zinc exposure on hormone levels, suggesting that MTE effects on reproductive outputs might not be explained by MTE-induced modifications of corticosterone, prolactin and testosterone-linked behaviours during incubation and rearing. Alternatively, MTE-induced reproductive impairments might result from MTE exposure having direct effects on offspring phenotypes or prenatal indirect effects on the embryo (e.g. maternal transfer of MTEs, hormones or immune compounds).

Relationship between Pb and Cd accumulations in house crow, their habitat, and food content from Klang area, Peninsular Malaysia

Heavy metal pollution has become a global concern due to accumulation in tissue and transferable effects to humans via the food chain. This study focused on monitoring the accumulation of cadmium (Cd) and lead (Pb) in surface soil and body content: bone, heart, brain, liver, lung, muscle, kidney, feathers, feces, and gizzard contents of house crow Corvus splendens in the Klang region, Malaysia. The results revealed the occurrence of Pb and Cd in all biological samples from house crows, food contents, and surface soil samples. Heart and kidney accrued high amounts of Cd, while high amounts of Pb were found to accumulate in bones and feathers. Major discrepancies were also discovered in the concentrations of metals between juvenile and adults, as well as female and male bird samples. Concentrations of Pb and Cd in house crow internal tissues correlated significantly with that of bird feathers, but none could be established with that of surface soil. In addition, a significant correlation was observed between Pb concentration in the internal tissues to that of the feces, but the same was not the case when compared with the surface soil concentration. Metal accrual in the house crows feathers and feces may be through a long-term transmission via the food chain, which are eliminated from feathers via molting. This may suggest the utility of molted breast feathers of house crow in the bio-monitoring of Cd and Pb contamination, whereas feces of house crow appear only to be suitable for the bio-monitoring of Pb contamination.

Spatial and interspecific variation of accumulated trace metals between remote and urbane dwelling birds of Pakistan

The current study was designed to evaluate the hypothesis that birds of urbanized and/or industrialized origin depict higher metal accumulation as compared to remote dwellers. We selected seven representative species from three families (Anatidae, Motacillidae and Sturnidae) at two different locations; Baroghil valley (remote location) and Soan valley (urbanized location) of Pakistan and analyzed the concentrations of 8 metals Pb, Cd, Cr, Ni, Cu, Mn, Fe and Zn in feathers of these species. Feathers from Soan valley which is under higher anthropogenic influence exhibited significantly (P<0.001) higher metal concentrations when compared with the feathers of the same species at Baroghil valley which has negligible anthropogenic input. Terrestrial birds of the Baroghil valley revealed greater metal loads than aquatic birds while at Soan valley it was vice versa. In general, elevated concentrations of metals were recorded in insectivorous species as compared to omnivorous species. Within each location, species belonging to Anatidae and Motacillidae revealed similar metal contamination patterns. Principal component Analysis (PCA) based on correlation matrices depicted a clear tendency of metals towards the species originating from areas with greater pollution load (Soan valley) than relatively undisturbed sites (Baroghil valley) and hence corroborated our hypothesis. The pattern of metal accumulation in feathers of both the locations suggested that there may be a flux of migration between the two regions and/or trans-boundary movement of pollutants/metals, which either singly or synergistically influence the overall metal profile in the studied bird species.

Avian feathers as a non-destructive bio-monitoring tool of trace metals signatures: a case study from severely contaminated areas

The concentrations of trace metals were assessed using feathers of cattle egrets (Bubulcus ibis), collected within two industrial areas of Pakistan, Lahore and Sialkot. We found, in order of descending concentration: Zinc (Zn), Iron (Fe), Nickel (Ni), Copper (Cu), Cadmium (Cd), and Manganese (Mn), Chromium (Cr), Arsenic (As), and Lithium (Li), without any significant difference (except Fe, Zn, and Ni) between the two areas. The concentrations of trace metals, we recorded were among the highest ever reported in the feathers of avian species worldwide. The concentrations of Cr, Pb, Cd were above the threshold that affects bird reproductive success. The high contamination by heavy metals in the two areas is due to anthropogenic activities as well to natural ones (for As and Fe). The bioaccumulation ratios in eggs and feathers of the cattle egret, their prey, and the sediments from their foraging habitats, confirmed that avian feathers are a convenient and non-destructive sampling tool for the metal contamination. The results of this study will contribute to the environmental management of the Lahore and Sialkot industrial areas.

Concentration of trace elements in feathers of waterfowl, Korea

Cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), and iron (Fe) were analyzed in the breast feather of white-fronted geese (Anser albifrons, n = 15), mallards (Anas platyrhynchos, n = 4), and spot-billed ducks (Anas poecilorhyncha, n = 13) found dead in Gimpo, Korea. All of the mallards and eight of the 13 spot-billed ducks had embedded shot. Concentrations of Pb, Cr, Cu, Mn, Zn, and Fe were significantly different among waterfowl species. Mallards with embedded shot had relatively higher Pb, Cr, Mn, and Fe concentrations than the other species. Cd and Cr in feathers of waterfowl species were within the range reported for other birds, and no specimen exceeded the tentative threshold effect levels of Cd (2 μg/g dry weight (dw)) and Cr (2.8 μg/g dw) for birds. However, Pb in feathers of all four mallards and two spot-billed ducks exceeded the threshold for deleterious effects (>4 μg/g dw). Essential elements such as Cu, Mn, Zn, and Fe in the feather of waterfowl species were not at toxic levels and within the background or normal range for the homeostatic mechanisms.

Spatial and temporal variation of lead, cadmium, and zinc in feathers of great tit and blue tit nestlings in Central Poland

In this study, we examined heavy-metal concentrations in feathers of nestling great tits Parus major and blue tits Cyanistes caeruleus at two different sites (urban parkland vs. deciduous forest) located in the Łódź agglomeration in relation to interyear variation. We found that tit species did not differ significantly in lead and cadmium concentrations. Zinc concentration was significantly higher in blue tits. We also found that lead and cadmium levels in blue tit nestlings and the level of lead in great tit nestlings were higher in the parkland site than in the woodland site. We explain habitat variation in heavy-metal concentrations in feathers of nestlings by different levels of contamination at study sites. For both tit species, significant variation in heavy-metal amounts accumulated by nestlings was found between years with the lowest value in a year with the lowest value of rainfall. We suggest that the interyear variation may be accounted for by differences in rainfall, thus influencing quantities of trace elements bioavailable in the environment.

Exposure to residual concentrations of elements from a remediated coal fly ash spill does not adversely influence stress and immune responses of nestling tree swallows

Anthropogenic activities often produce pollutants that can affect the physiology, growth and reproductive success of wildlife. Many metals and trace elements play important roles in physiological processes, and exposure to even moderately elevated concentrations of essential and non-essential elements could have subtle effects on physiology, particularly during development. We examined the effects of exposure to a number of elements from a coal fly ash spill that occurred in December 2008 and has since been remediated on the stress and immune responses of nestling tree swallows. We found that nestlings at the site of the spill had significantly greater blood concentrations of Cu, Hg, Se and Zn in 2011, but greater concentrations only of Se in 2012, in comparison to reference colonies. The concentrations of elements were below levels of significant toxicological concern in both years. In 2011, we found no relationship between exposure to elements associated with the spill and basal or stress-induced corticosterone concentrations in nestlings. In 2012, we found that Se exposure was not associated with cell-mediated immunity based on the response to phytohaemagglutinin injection. However, the bactericidal capacity of nestling plasma had a positive but weak association with blood Se concentrations, and this association was stronger at the spill site. Our results indicate that exposure to these low concentrations of elements had few effects on nestling endocrine and immune physiology. The long-term health consequences of low-level exposure to elements and of exposure to greater element concentrations in avian species require additional study.

Breeding performance of blue tits (Cyanistes cæruleus ultramarinus) in relation to lead pollution and nest failure rates in rural, intermediate, and urban sites in Algeria

The breeding parameters and the egg and nestling morphology of Cyanistes caeruleus populations from rural, intermediate, and urban sites in Algeria and the relationships of those variables with lead contamination were studied during three consecutive years. Breeding success was explained only by predation and vandalism rates. Predation was higher in the rural area, whereas vandalism was higher in the urban site. The other measured breeding parameters and egg characteristics were relatively insensitive to study site. The morphology of urban nestlings exhibited a trend toward smaller body size and mass compared to individuals from intermediate and rural sites. Although lead concentrations were higher in the tissues of urban birds than in intermediate and rural individuals, we did not detect a clear influence of this variable on nestling morphology. We conclude that urbanization influenced blue tit breeding parameters through predation and vandalism and nestling morphology through mechanisms other than lead pollution.

Plasma carotenoid levels are not directly related to heavy metal exposure or reproductive success in three insectivorous passerines

The authors measured plasma carotenoid levels in three insectivorous bird species, the pied flycatcher (Ficedula hypoleuca), the blue tit (Cyanistes caeruleus), and the great tit (Parus major) in metal-polluted and unpolluted sites around a copper smelter. Their aim was to determine whether there was interspecific, age-related, or yearly variation in carotenoid levels and their responses to the ambient pollution level. The three bird species showed qualitatively and quantitatively similar carotenoid profiles, with lutein being always the predominant plasma carotenoid. Ficedula hypoleuca nestlings showed higher plasma carotenoid levels in the unpolluted than in the polluted area, whereas no significant differences were found in F. hypoleuca females or in nestlings or females of the Parids. Yearly comparison of plasma concentrations (only for P. major nestlings) showed, however, that levels varied nonsynchronously between polluted and unpolluted sites among the breeding seasons, with the yearly variation being higher in the polluted area. The survival of nestlings did not depend on their plasma carotenoid concentrations. The two Parid species showed lower nestling survival at sites with high metal exposure levels. The authors conclude that plasma carotenoid levels showed a marked spatial, temporal, and age-related variation, but were not directly related to heavy metal exposure or the reproductive success of birds.

Breeding performance of passerines in a polluted oasis habitat in southern Tunisia

We investigated the breeding performance of passerines nesting in the oases close to Gabès city, one of the most industrialised areas in Tunisia, in relation to habitat pollution. Using data on nest survival, clutch size and chick productivity of four insectivorous passerine species, we assessed whether the proximity to Gabès-Ghannouche factory complex of phosphate treatment was associated with reduced breeding performance. Our results show evidence of decreased breeding performance near the factory complex, but this decrease was more perceptible when comparing one oasis situated at the vicinity of the factory complex (polluted oasis) with one control oasis situated tens of kilometres faraway, than when comparing sites situated hundreds of metres apart within the polluted oasis. Overall, these results would indicate that passerines offer suitable models for biomonitoring programmes in the Gabès region and underline once more the usefulness of passerines as reliable biomonitors of terrestrial ecosystems.

Are great tits (Parus major) inhabiting the vicinity of a pulp mill healthy? Impacts on physiology and breeding performance

The evaluation of pollution effects on wildlife provides biologically meaningful information concerning environmental quality and possible impacts on populations and can be used as an early warning of environmental change. We aimed to assess the potential effects of exposure to atmospheric pollution from pulp mill emissions on the morphology, physiology, and reproductive performance of the great tit (Parus major). Great tits from a population inhabiting the vicinity of a pulp mill had significantly higher feather mercury levels and were physiologically distinct from other birds not under the direct influence of the pollution source. This distinction, due to significantly higher levels of red blood cell-glutathione peroxidase antioxidant activity, in birds from the vicinity of the pulp mill, was observed both in autumn and winter and was repeatable between years. No detectable effects were observed on breeding performance or nestling morphology and physiology. The effects of pollution in this study seem to be related to increased levels of oxidative stress.

Metal accumulation and performance of nestlings of passerine bird species at an urban brownfield site

The use of passerine species as bioindicators of metal bioaccumulation is often underutilized when examining the wildlife habitat value of polluted sites. In this study we tested feathers of nestlings of two common bird species (house wren and American robin) for accumulation of Pb, Zn, As, Cr, Cu, Fe in comparison of a polluted, urban brownfield with a rural, unpolluted site. House wren nestlings at the study site accumulated significantly greater concentrations of all target metals except Zn. At the polluted site we found significant species differences of metal concentrations in feathers, with house wrens accumulating greater concentrations of Pb, Fe, and Zn but slightly lesser accumulations of Cr and Cu than American robins. Although house wren nestlings demonstrated significant accumulation of metals, these concentrations showed little effect on size metrics or fledge rates during the breeding season compared to nestlings from the control site.

Breeding performance of blue tits (Cyanistes caeruleus) and great tits (Parus major) in a heavy metal polluted area

We compared heavy metal levels, calcium levels, breeding parameters and condition of nestling and adult Cyanistes caeruleus and Parus major along a heavy metal pollution gradient. Both species started laying earlier and showed inferior nestling growth and smaller fledging probability in the polluted areas, which are phenologically advanced in spring due to sparse forests. The major inter-specific difference in the responses was that the clutch size and hatching success were decreased in the polluted area in P. major, but not in C. caeruleus. Heavy metal profiles in nestling feces were relatively similar in the two species, though Ni and Pb levels were higher in C. caeruleus than in P. major. However, the latter species showed markedly higher fecal calcium concentrations. Lower calcium levels and higher levels of some heavy metals in C. caeruleus suggest that in Ca-deficient environments this species might be more susceptible to negative pollution effects than P. major.

Assessment of environmental contamination using feathers of Bubulcus ibis L., as a biomonitor of heavy metal pollution, Pakistan

Concentrations of metals such as Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, Pb, and Zn were analyzed in the feathers of cattle egret (Bubulcus ibis) from three breeding colonies in the Punjab province, Pakistan. The mean concentrations of Ca, Cd, Fe, Pb and Mn were significantly different between the three study sites (River Chenab, River Ravi and Rawal Lake Reservoir). The mean concentrations of Ca, Cd, Fe and Mn were significantly greater at the River Chenab heronry and Cr, Co, Zn, and Pb concentrations at the River Ravi heronry. The feathers of cattle egrets collected from the Rawal Lake Reservoir heronry were least contaminated. Multivariate statistical methods viz., Factor Analysis based on Principal Component Analysis (FA/PCA); Hierarchical Cluster analyses (HACA), and Correlation Analyses identified relatively similar associations of metals and their sources of input. Metals such as Ca, Mg, and K were related with natural input from parent rock material whereas trace metals viz., Cu, Cd, Co, Pb, Ni, and Zn were associated mainly with anthropogenic processes. Metals such as Fe, Mn, and Li were either correlated with natural input or with anthropogenic activities. Concentration of heavy metals such as Cd, Pb, and Cr were well above the threshold level that can cause adverse effects in birds and pose menace to the cattle egrets population in Pakistan. The study suggested that the feathers of cattle egret could be used as a bio-monitor of the local heavy metals contamination.

Trace metal concentration in Great Tit (Parus major) and Greenfinch (Carduelis sinica) at the Western Mountains of Beijing, China

We examined the concentrations of 11 trace metals in tissues from 10 body parts of Great Tits and Greenfinches collected at Badachu Park in the Western Mountains of Beijing, China to assess the metal accumulation level, distribution among body parts, and species and gender related variations. The highest concentrations of Hg, Ni, Zn, and Mn were found in the feather; Pb and Co in the bone; Cd, Cr, and Se in the kidney, and Cu in the liver and heart. Metal concentrations had substantial interspecific variation with Great Tits showing higher levels of Hg, Cr, Ni, and Mn than Greenfinches in tissues of most body parts. Gender related variations were body part and species specific. Meta-analyses using data from this study and other studies suggested that metal concentrations of Great Tits at our study site were relatively low and below the toxic levels.

Lead concentrations in feathers and blood of common blackbirds (Turdus merula) and in earthworms inhabiting unpolluted and moderately polluted urban areas

Despite the dramatic decrease of atmospheric lead (Pb) concentrations in urban areas of most industrialised countries, we hypothesised that urban common blackbirds (Turdus merula) may still be contaminated by Pb concentrations of toxicological concern due to transfer from soil through the food chain. We sampled blackbirds and earthworms, one of their main preys, in Besançon, a middle-size city of Eastern France (where atmospheric Pb concentrations decreased from 0.5 microg/m(3) in 1987 to nearly 0 in 2002) and in a rural reference site. Lead concentrations were determined in the tissues of the different functional groups of earthworms (anecic, epigeous and endogeous) and in blood, washed and unwashed outermost tail feathers and breast feathers of blackbirds. Fresh masses and an index of individual body condition were measured in the two blackbird populations as biomarkers of possible toxic effects. Lead concentrations in earthworms did not differ among functional groups but were significantly higher in urban individuals than in rural ones. Concentrations in outermost tail feathers, breast feathers and blood were significantly higher in urban blackbirds (7.75+/-4.50, 3.15+/-1.77 and 0.15+/-0.09 microg/g, respectively) than in rural individuals. In urban blackbirds, concentrations in washed and unwashed outermost tail feathers allowed estimating the external contamination (probably due to deposition of dusts and/or to excretion of the uropygial gland) at 37% of the total Pb concentration of the unwashed feathers. Remaining 63% should be linked to food chain transfer of persistent Pb from urban soils. Among the 23 sampled blackbirds, 4 of them (3 in the urban site and 1 in the rural site) exhibited blood Pb concentrations higher than the benchmark value (0.20 microg/g) related to subclinical and physiological effects in birds. Variations in body condition index were not correlated to Pb concentrations in blackbird tissues. Present results suggest that Pb may still be of environmental concern for blackbirds in urban areas because of the persistence of Pb in soils and its transfer through the food chain.