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1 March 2018 Predation risk-induced adjustments in provisioning behavior for Horned Lark (Eremophila alpestris) in British Columbia
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Parental provisioning rates influence nestling development with consequences for their survival and fitness as adults, but provisioning behavior can be disrupted by predation risk. For an alpine population of Horned Lark (Eremophila alpestris) on Hudson Bay Mountain, British Columbia, we tested the effects of perceived predation risk on parental provisioning behavior. Using a repeated measures experimental design, we presented nests with decoys representing 3 levels of predation risk: (1) a scent-oriented predator (red fox; Vulpes vulpes), (2) a visually oriented predator (Common Raven; Corvus corax), and (3) a noncompetitive sympatric species (Savannah Sparrow; Passerculus sandwichensis) as a control. We found that elevated perceived predation risk decreased parental nest visitation rate by 65.6% compared to the control rate (mean 0.64 [SE 0.04] visits per 10 min), with no difference in response to predators that use visual (raven: 0.17 [0.03]) or olfactory (fox: 0.27 [0.04]) cues after controlling for zero inflation. Although background levels of provisioning behavior differed between sexes, we found no evidence for sex-specific responses to perceived predation risk. Horned Larks did not compensate for reduced visitation rates by increasing prey bill-load size, and thus an overall decrease in biomass delivery occurred during predator presentations. Females increased nest visitation rates immediately (30 min period) following fox decoy presentations, however, such that the net biomass delivery rate was comparable to control rates. This immediate compensatory behavior was not observed for females following raven treatments or for males. We showed that Horned Lark parents can assess and respond to increased perceived predation risk and provide evidence for compensatory provisioning behavior, which may indicate the potential to cope with habitats experiencing elevated mesopredator densities.

Elizabeth L. Goullaud, Devin R. De Zwaan, and Kathy Martin "Predation risk-induced adjustments in provisioning behavior for Horned Lark (Eremophila alpestris) in British Columbia," The Wilson Journal of Ornithology 130(1), 180-190, (1 March 2018).
Received: 10 September 2016; Accepted: 21 April 2017; Published: 1 March 2018

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