insects Article Avian Predation in a Declining Outbreak Population of the Spruce Budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae) Jacques Régnière 1,* , Lisa Venier 2 and Dan Welsh 3,† 1 Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 rue du PEPS, Quebec City, QC G1V 4C7, Canada 2 Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. E., Sault Ste. Marie, ON P6A 2E5, Canada;
[email protected] 3 Environment and Climate Change Canada, Canadian Wildlife Service, Ottawa, ON K1A 0H3, Canada * Correspondence:
[email protected] † Deceased. Simple Summary: Cages preventing access to birds were used to measure the rate of predation by birds in a spruce budworm population during the decline of an outbreak. Three species of budworm-feeding warblers were involved in this predation on larvae and pupae. It was found that bird predation is a very important source of mortality in declining spruce budworm populations, and that bird foraging behavior changes as budworm prey become rare at the end of the outbreak. Abstract: The impact of avian predation on a declining population of the spruce budworm, Cho- ristoneura fumifereana (Clem.), was measured using single-tree exclosure cages in a mature stand of balsam fir, Abies balsamea (L.), and white spruce, Picea glauca (Moench.) Voss. Bird population Citation: Régnière, J.; Venier, L.; censuses and observations of foraging and nest-feeding activity were also made to determine the Welsh, D. Avian Predation in a response of budworm-linked warblers to decreasing food availability. Seasonal patterns of foraging. Declining Outbreak Population of the as well as foraging success in the declining prey population was compared to similar information Spruce Budworm, Choristoneura from birds observed in another stand where the spruce budworm population was rising.