RP8 Ecotoxicology of Agrochemicals and Pharmaceuticals
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(MAR-1117-228361) Reproduction and health of American kestrels breeding in agroecosystems in southwestern Ontario.

Martin, P.¹, Barrett, G.¹, Marvin, C.², Sverko, E.², ¹ Canadian Wildlife Service, Environment Canada, Burlington, Ontario, Canada² National Water Research Institute, Environment Canada, Burlington, Ontario, Canada

ABSTRACT- American kestrels are common though declining throughout the agricultural landscape of southern Ontario. They readily nest in nestboxes in agricultural land, forage on rodents, passerines and insects in farm fields and edges, typically within 1 km from their nest site, and hence provide a good upper trophic level avian model to monitor the health of terrestrial wildlife in agroecosystems. In southern Ontario, DDT was used throughout the mid-1900s and persists in soil to varying levels depending on the degree of agricultural usage; in addition, the types and intensity of use of current use pesticides vary among agroecosystems. We measured legacy organochlorine pesticides (OCs), as well as the currently used OC, endosulfan, in kestrel eggs, and atrazine in the plasma of kestrel chicks and monitored the reproductive success, growth and various biomarkers of the health of kestrel chicks produced from nestboxes on 5 trails in orchard, tobacco, corn-soy and low intensity mixed agricultural areas in 2002 to 2004. DDE levels in eggs of kestrels were highest in the Niagara orchard area relative to all others, and intermediate in a second orchard area. Clutch size, hatching and fledging success did not differ among crop type or area, although all variables were lower in 2003 than 2002. In all years however, significantly more male kestrels were raised in tobacco than orchard areas (2.15 versus 1.26 males per box). Nest success did not vary between areas; however the incidence of brood reduction was greater in orchard regions. However, pre-fledge nestlings were significantly larger in orchard than other areas. Circulating levels of thyroid hormones and retinol in nestlings did not differ among regions and did not correlate with DDE levels in sibling eggs. However, we found an decreased cutaneous T-lymphocyte-mediated response to the mitogen phytohemagglutinin in nestlings from orchard areas.

Key words: organochlorines, current-use pesticides, kestrels, agroecosystems