Assessing Contamination Profiles in Livers from Road-Killed Owls

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Wildlife Health

Background:

• Raptors, particularly owls, serve as crucial sentinel species for environmental contaminant monitoring due to their high trophic levels and broad foraging ranges.
• Understanding contaminant exposure patterns in owls is vital for assessing ecosystem health and identifying potential risks to wildlife and humans.

Purpose of the Study:

• To investigate and compare the levels and patterns of various organic contaminants in five species of road-killed owls from Alentejo, Portugal.
• To evaluate how species, age, and sex influence the bioaccumulation of contaminants like organochlorine pesticides (OCPs), per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs).

Main Methods:

• Carcasses of five owl species (eagle owl, long-eared owl, little owl, tawny owl, barn owl) were collected after being found road-killed.
• Livers were analyzed for 81 organic contaminants, including OCPs, PFAS, PCBs, PAHs, pharmaceuticals, in-use pesticides, and organophosphate esters (OPEs).
• Principal component analysis was used to identify differences in contaminant patterns among species, age groups, and sexes.

Main Results:

• Twenty-one out of 81 contaminants were detected; organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were prevalent, followed by perfluorooctane sulfonic acid (PFOS).
• Eagle owls and long-eared owls exhibited higher concentrations of OCPs, PCBs, and PFOS, correlating with their higher trophic positions.
• Tawny owls, barn owls, and little owls showed higher levels of polycyclic aromatic hydrocarbons (PAHs), linked to their use of urban and roadside habitats.

Conclusions:

• Contaminant exposure patterns varied significantly among owl species, reflecting differences in diet and habitat preferences, even among species with similar diets.
• Adult owls had higher concentrations of OCPs and PCBs than juveniles, indicating accumulation over time.
• The study highlights the utility of owls as bioindicators, revealing distinct contamination profiles influenced by ecological niche and life history traits.