Biological monitoring of heavy metal contaminations using owls

Concentration of metals and metalloids in livers of birds of various foraging guilds collected during the autumn migration period in Poland

During migration, birds explore various habitats at stopover sites that differ in food resources and contamination levels. In this study, hepatic concentrations of 21 elements (metals and metalloids) in 11 species of birds, representing various foraging habitats (such as aquatic, aquatic/terrestrial, and terrestrial) and migration modes (migratory and sedentary) representing various foraging guilds (omnivores, piscivores, and molluscivores), were analyzed. The samples (N = 84) were collected during the autumn migration period in Poland. The concentrations of elements determined in this study exhibited high inter-species variability, reflecting the diversity in contamination levels depending on food resources used by specific bird groups. Many of the investigated individuals from different species showed exceeded levels of subclinical toxicity and moderate clinical poisoning due to Cd and Hg. Higher concentrations of As, Hg, and Ba and lower V concentrations were found in migratory birds as compared to sedentary birds. Species foraging in terrestrial habitat had different concentrations of some elements compared to aquatic and aquatic/terrestrial species. Some specific inter-species differences in hepatic elemental concentrations were found. Differences in elemental concentrations among various groups can primarily be attributed to their foraging guilds, with certain elements, particularly As, V, and Hg, playing a significant role in the dissimilarity of elemental concentrations between foraging habitat groups and migratory mode groups. The data collected confirmed the limited ability of As to enter ecosystem pathways. The results of this study contribute to understanding the year-round exposure of migratory birds to environmental contamination, which can have carry-over effects on their performance in wintering and breeding grounds.

Analysis of Toxic Heavy Metals in the Pellets of Owls: A Novel Approach for the Evaluation of Environmental Pollutants

Massive quantities of unadvisable synthetic pesticides are used in modern agricultural industries in order to increase productivity to convene food demands. Wild birds are an excellent bio-indicator of environmental contaminations as pesticides and heavy metals are intentionally highly hazardous pollutants. Considerably, raptorial birds (owls) attract consumers in the food chain and food web because they have wider forager and foraging grounds. In the current investigation, owl pellets were used as a viable tool and novel approach to detecting environmental contaminants. In total, 30 pellets comprising five species were collected from selected farmlands, and 11 metals (Cr, Mn, Co, Mo, Se, V, Cu, Ni, Pb, Zn, and Fe) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Undeniably, the Brown Fish Owl showed more metal accumulation than the Barn Owl, Spotted Owl, Indian Eagle Owl, and Mottled Wood Owl. Among the species, the levels of metals such as Manganese (Mn), Molybdenum (Mo), Vanadium (V), Copper (Cu) and Zinc (Zn) varied significantly (p < 0.05). Nonetheless, the research revealed that the agroecosystem was contaminated with heavy metals. The present outcome highlights that the management of the environment, especially the agroecosystem, must be examined with a careful assessment of contaminants, and it is a vital resource for human and other related wildlife faunal communities.

Evidence of Low-Habitat Contamination Using Feathers of Three Heron Species as a Biomonitor of Inorganic Elemental Pollution

The concentration of 12 elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) has been investigated in the feathers of three species of Ardeidae, namely the Grey Heron Ardea cinerea, the Little Egret Egretta garzetta, and the Cattle Egret Bubulcus ibis, all breeding at a colony located in the southern Padana Plain (NW Italy). This study is a first step for an evaluation of possible direct effects of these elements on chicks' survival and growth rate. Fe, Zn, Cu, and Mn were in the range 7-69 mg Kg-1, while lower levels of Pb, Ni, As, and Se (0.27-1.45 mg Kg-1) were measured. Co, Cd, and Cr were close to the method detection limits (MDLs) in all the species. The measured concentrations of the most abundant trace elements, such as Zn and Cu, seem to reflect the geochemical pattern of the background (running water and soil), while Hg concentration is lower and it appears to be biomagnified, particularly in Grey Heron feathers. Its concentration is higher in adults than in chicks, and it differs among the three species, as it is closely related to the fish-based dietary pattern. The measured trace elements' concentrations are below the threshold levels in all the heron species, and consequently, harmful and acute effects on the local population are unlikely; the conservation status of herons populations in northern Italy is probably more affected by other factors, such as climate changes, altered aquatic environment, and, consequently, food quality.

Temporal Changes in Concentrations of Lead and Other Trace Metals in Free-Ranging Eurasian Eagle Owls Bubo bubo in Sweden

Patterns of lead and other trace metals were examined in 122 Eurasian eagle owls Bubo bubo found dead in Sweden in the period 1978-2013. Environmental lead (Pb) has decreased over recent decades from reduced anthropogenic emissions but mortality by Pb poisoning is still frequently reported for avian raptors and scavengers exposed to Pb ammunition. One objective here was to determine if Pb concentrations in a nocturnal non-scavenging raptor follow the general decline observed in other biota. Pb concentration in owl liver was significantly correlated with body weight, sex, latitude, longitude and season. Pb showed a significant decreasing trend towards north and west. Starved birds had significantly higher concentrations. Total Pb concentrations in liver averaged 0.179 μg g^-1 dry weight (median 0.103) and decreased by 5.6% per year 1978-2013, or 5.3% after adjustment for confounding factors, similar to trends in other species. Among 14 other trace elements only antimony and arsenic showed decreasing trends. Lead isotope ratios ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb increased from 1.138 and 2.408 in 1978-1985 to 1.170 and 2.435 in 2010-2013, respectively, demonstrating that the decreasing Pb concentration in eagle owl is related to the phase-out of leaded gasoline in Europe, where Pb additives had much lower isotope ratios than natural lead in Swedish soils. Only one incidence of suspected Pb poisoning (40.7 μg g^-1 in liver) was observed indicating that poisoning from ingestion of metallic lead is rare (< 1%) in eagle owl in Sweden, in contrast to what has been reported for eagles.

Metal Concentrations in Eurasian Eagle Owl Pellets as a Function of Reproductive Variables in Korea

Eight metals were analyzed in the pellet of Eurasian eagle owls (Bubo bubo) breeding in Korea: Paju, Ganghwa, Gimpo, and Sihwa, Gyeonggi-do (N = 15, respectively). Except for cadmium (Cd), concentrations of all metals differed among sites (ANOVA, p < 0.001); Sihwa had relatively higher metal concentrations compared with other sites. Clutch size did not differ among the four sites. However, Sihwa had the greatest nesting success and number of fledglings (per hatchlings and laid egg) and highest mean weight of diet. Lead concentrations in the pellets were generally lower than the excrements of various birds worldwide. We suggest that all metal concentrations in pellets do not negatively affect the reproduction of Eurasian eagle owls, and food supply at Sihwa seems likely more important to breeding success than metal contamination.

Trace element contamination in nestling black-tailed gulls (Larus crassirostris) in Korea

At Hongdo Island, Gyeongsangnam-do, Korea, a breeding site of black-tailed gull (Larus crassirostris), we collected nestlings from two locations: a "reference" site (n = 10) with no known source of lead contamination and "lighthouse" site (n = 10) with suspected lead contamination from leaded paint. Iron concentrations in the kidney and bone, manganese in the muscle, copper in the bone, lead in the muscle and bone, and cadmium in the liver, muscle, and bone at the reference site were significantly higher than at the lighthouse. Manganese concentrations in the liver and kidney, and lead in the kidney were significantly greater at the lighthouse than at the reference site. Iron, zinc, manganese, copper, lead and cadmium concentrations had tissue-specific accumulation at both sites. Lead concentrations in 10 % of livers and in 80 % of kidneys at the lighthouse, and in 20 % of livers from the reference were within a range considered toxic (>6.00 μg/g dw in the liver and kidney). Lead concentrations in 50 % of black-tailed gull nestlings at the reference and 80 % nestlings at the lighthouse were greater in livers than in bones, which is suggestive of acute lead exposure. For cadmium, all liver and kidney concentrations from two sites were at a level considered background in birds. Cadmium concentrations of every sample were higher in kidneys than in livers, suggestive of chronic cadmium exposure. Lead concentrations in gull nestlings in the present study were relatively higher than other gull species worldwide, but cadmium concentrations were relatively lower.

Tissue distribution of metals in white-fronted geese and spot-billed ducks from Korea

This study presents concentrations of Fe, Zn, Mn, Cu, Pb and Cd in livers, kidneys, muscles and bones of white-fronted geese Anser albifrons (geese) and spot-billed ducks Anas poecilorhyncha (ducks). Iron in livers, kidneys and muscles, Zn in muscles, Mn and Cd in every tissue, Cu in livers, muscles and bones and Pb in bones differed between species, and there were significant differences among tissues in both species. Essential elements such as Fe, Zn, Mn and Cu concentrations were within the background levels. Lead concentrations in livers of 7 of 14 geese and 7 of 19 ducks and in bones of 4 of 19 ducks exceeded background concentrations for waterfowl (5 μg/g dw for the liver, 10 μg/g dw for the bone). Almost all samples of both species had the background Cd concentrations in the liver (33 of 33 geese and ducks) and kidney (14 geese and 18 ducks). Tissue concentrations of Cd were greater in geese than ducks. In contrast, tissue concentrations of Pb in bones were greater in ducks than in geese. These different trends for Cd and Pb reflect a short and/or long term difference in exposure and degree of accumulation of these metals.