T5 AM Terrestrial Ecotoxicology
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 321-323

(MOR-1117-823994) Woodpecker exposure to monosodium methanarsonate (MSMA) as used for bark beetle control in British Columbia pine forests.

Morrissey, C¹, Dods, P¹, Wilson, L¹, Cullen, W², Williams, T³, Elliott, J¹, ¹ Canadian Wildlife Service, Environment Canda, Delta, BC, Canada² University of British Columbia, Vancouver, BC, Canada³ Simon Fraser University, Burnaby, BC, Canada

ABSTRACT- Outbreaks of the mountain pine beetle (Dendroctonus ponderosae Hopkins) have caused significant damage to pine forests in British Columbia, Canada. Several management strategies have been applied to reduce timber losses including the use of an arsenic based pesticide monosodium methanearsonate (MSMA). Since insectivorous birds, particularly woodpeckers, are attracted to beetle outbreaks due to increased food availability, we assessed woodpecker exposure to MSMA treated trees. In total, 401 beetle infested trees (reference) and 449 MSMA treated trees were scored for the amount of debarking at the time of infestation/treatment and again one year later. Debarking indices indicated woodpecker foraging of MSMA treated trees was significantly lower than non treated trees. However, approximately 30% of MSMA trees had some evidence of woodpecker foraging (5%-100% debarked). Focal observations of radio tagged Hairy and Three-toed woodpeckers and point count surveys in MSMA treatment areas confirmed woodpeckers regularly occupied MSMA stands during the breeding season. Analysis of blood from woodpeckers breeding near MSMA stands further confirmed elevated blood arsenic concentrations. Total arsenic in mountain pine beetles from treated trees ranged from 13.94- 354.1 g/g dw with the organic metabolite monomethyl arsine (MMAA) contributing over 90% to the total arsenic extracted while beetles from reference trees averaged 0.11 g/g dw total arsenic. A significant negative relationship existed between total As concentrations in beetles and the amount of debarking, indicating woodpeckers were feeding more from trees with lower arsenic levels and possibly targeting those trees with greater live beetle broods. Given the extent of mountain pine beetle infestation and the uncertainty surrounding the future use of MSMA in British Columbia, this study addresses important data gaps on woodpecker exposure and potential toxicity to MSMA.

Key words: woodpeckers, arsenic, bark beetles, forestry