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Monday, April 9 • 2:15pm - 2:30pm
INSECT & DISEASE OUTBREAKS: Insectivorous Birds as Indicators of Future Defoliation by the Spruce Budworm

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AUTHORS: Marion Germain*, University of Quebec in Montreal; Marc-André Villard, University of Quebec in Rimouski; Louis de Grandpré, Service Canadien des Forêts; Patrick James, University of Montreal; Dan Kneeshaw, University of Quebec in Montreal; Udaya Vepakomma, FPInnovations; Jean-François Poulin, WSP

ABSTRACT: Spruce budworm outbreaks are the most significant disturbance in North American boreal forests. Large-scale, spatially synchronous outbreaks occur periodically, causing significant mortality or growth reduction in spruce and fir over large areas. The current outbreak was first detected in 2006 on the North Shore of the St. Lawrence River and has affected >7 million ha so far. Efficient forest protection against defoliation requires early intervention, but early detection of outbreaks remains challenging. Ground-based surveys cannot be applied over large areas and aerial surveys of current defoliation cannot be used to guide early intervention. In this context, we investigated whether bird population densities can be used as indicators of future defoliation to guide early intervention. Specifically, we modelled the relationships between the occurrence of Tennessee Warbler, Cape May Warbler, and Bay-breasted Warbler and cumulative spruce budworm defoliation at different temporal lags. Using data from a large-scale (>174 000 km²) bird survey conducted between 2006 and 2016 (>1500 point counts) and annual defoliation data in Québec’s North Shore region, we explored the numerical response of each focal bird species to defoliation from 3 years before the count to 6 years after while accounting for spatial variation. Preliminary results confirm the numerical increase of each “budworm warbler” species with increasing defoliation. We also expect species-specific patterns in numerical response, with Cape May Warbler increasing earlier than Bay-breasted and Tennessee Warblers due to the different ways that each of these species use different levels of the tree crown. We expect that our landscape-level models of how warblers respond to defoliation will serve as an effective tool for forest protection by helping to identify outbreaks and to guide early intervention strategies.

Monday April 9, 2018 2:15pm - 2:30pm CDT
LaSalle 2 (7th Floor)