Avian regulation of crop and forest pests, a meta-analysis.

BACKGROUND: Birds have been demonstrated to reduce pest effects on various ecosystem types. This study aimed to synthesize the effect of birds on pest abundance, damage on product and yields in agricultural and forest systems in different environments. Our hypothesis is that birds are effective pest regulators that contribute to reduction of pest abundance, enhancement of yield quality and quantity, and economic profit, and that pest regulation may depend on moderators such as the type of ecosystem, climate, pest, and indicator (i.e., ecological or economic indicators).

RESULTS: We performed a systematic literature review of experimental and observational studies related to biological control in presence and absence of regulatory birds. We retained 449 observations from 104 primary studies that were evaluated through qualitative and quantitative analyses. For those 79 studies with known effects of birds on pest regulation, nearly half of the 334 observations showed positive (49%), 46% showed neutral, and very few (5%) showed negative effects. Overall effect sizes were positive (mean Hedges'd = 0.38 ± 0.06). A multiple model selection retained only ecosystem and indicator types as significant moderators.

CONCLUSION: Our results support our hypothesis that there is a positive effect of avian control of pests for each analyzed moderator and this effect was significant for both ecological and economic indicators. Avian regulation of pests is a potential effective approach for environmental-friendly pest management that can reduce pesticide use regardless of the context of implementation. This article is protected by copyright. All rights reserved.