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Date of Award
Master of Science (MS)
Bodensteiner, Leo R.,1957-
Matthews, Robin A., 1952-
Steensma, Karen M. M.
Bird damage to fruit crops causes major economic loss to growers. The Pacific Northwest leads sweet cherry production in North America, but few studies highlight the impacts of bird damage to cherries in this region. Growers currently employ a diverse range of bird-deterrent strategies, but there is little information regarding efficacy. A low-impact management practice common to the region is the use of kestrel nest boxes in orchards. The American kestrel (Falco sparverius), is a small falcon that may mitigate damage because it is territorial and preys on birds. My research objectives were to quantify bird damage and identify pest-bird species in Pacific Northwest sweet cherries, to determine whether kestrels were associated with reductions in bird damage and pest-bird density, and to determine which of the following factors were associated with high damage: distance from individual trees to the orchard edge, orchard size, bird-management practices and bird density. In 2013 I quantified and compared bird damage within paired plots for 8 plots with occupied kestrel boxes and 8 plots without kestrels. In 2014 I quantified bird damage, conducted variable-width transect surveys of birds, and monitored kestrel boxes in 19 orchard blocks. I used distance sampling methods to calculate bird density at each site and in relation to kestrel boxes. I compared amounts of damage and bird density at varying distances from occupied kestrel boxes. I classified orchards by size and bird density and compared damage among classes. In both years I looked for a linear relationship between percent bird damage on a branch and distance from the tree to the orchard edge and I quantified bird-management practices encountered, assigned a management rank to each site and compared damage among ranks. I observed low damage rates overall, with mean losses of 2.08% in 2013 and 1.17% in 2014. Median losses were 2.09% and 0.83%, respectively. Damage was significantly lower in two kestrel plots compared to paired plots without kestrels in 2013, but results were potentially confounded by edge effects. Kestrels did not appear to influence amounts of damage or bird density in 2014. In 2014 damage was higher near orchard edges and in small orchards with high bird density. Trends related to bird management were ambiguous. Cherry-eating birds accounted for 84% of detections for 22 species observed in orchards. American robins (Turdus migratorius), American goldfinches (Spinus tristis) and house finches (Haemorhous mexicanus) were the most abundant, representing 35%, 16% and 12% of detections.
Bird pests--Control--Northwest, Pacific, Cherry--Diseases and pests--Control--Northwest, Pacific, American Kestrel--Behavior--Northwest, Pacific
Western Washington University
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Leigh, Deanna K., "The Effect of American Kestrels on Deterrence of Bird Damage to Pacific Northwest Sweet Cherries" (2015). WWU Graduate School Collection. 457.