Monitoring organochlorine compounds in feathers and livers of Barn Owls Tyto alba from South Portugal: variations with sex and age.

Abstract

Organochlorine compounds (OC) include the most prevalent synthetic pesticides that have been broadly used in agriculture in the second half of the 20th century. Given its preference for farmland hunting grounds the Barn Owl Tyto alba is a good candidate to biomonitor the potential health risks of OC to humans and wildlife. We evaluated the efficacy of Barn Owl feathers and livers for monitoring OC and sex and age class differences. Primary feathers and livers from 15 owls collected along roads (2009 to 2013) were analyzed for 14 OC (α-HCH, ß- HCH, δ-HCH, lindan, heptaclor, heptaclor epoxide, endosulfan I and II, aldrin, dieldrin, endrin, DDD, DDE and DDT). Wilcoxon matched pairs tests were used t o compare between feathers and livers from each individual and Mann-Whitney tests were used to compare differences between sexes (8 females and 5 males) and age classes (6 first year and 9 older birds). The most abundant compounds in our study were β-HCH (4587±4528 ng g-1) and heptachlor (2530±2501 ng g-1) measured in feathers, representing respectively 55 % and 31 % of the sum of OC in our sample. All OC were detected in feathers, while in livers δ -HCH, DDT and DDD were not detected. DDE (45.39±50.37 ng g-1) was the compound with higher mean concentration in livers. We detected no differences between sexes (feathers and livers) and age classes (feathers) but in livers first year barn owls had higher levels of heptachlor epoxide (1.22±1.16 ng g-1; w=44.5;p=0.02) and endrin (31.9±54.7 ng g-1; w=49.5; p>0.01) than older birds (heptachlor epoxide: 0.209±0.440 ng g-1; endrin: nd). Feathers allowed for detecting mean concentrations 45.6 times superior than in livers (from 0.1 for DDE up to 300 times superior for β-HCH); using livers alone would have missed 21% of the OC present in owls.