Orchard management factors affecting rates of bud damage to kiwifruit orchards

Abstract

Although bird damage to fruit crops is well documented, bird damage to flower and leaf buds is relatively understudied. In Aotearoa/New Zealand, bird damage to kiwifruit (Actinidia deliciosa and Actinidia chinensis) buds has been reported to be widespread. However, the responsible bird species and rates of damage have not been investigated, nor is it known if orchard management such as the presence of shelterbelts, and management of swards (grass) between vines or characteristics of the surrounding landscape affect patterns of bud damage. We aimed to identify the bird species responsible for damage to kiwifruit buds, the extent of damage across orchards, and factors correlated with bud damage. A combination of bird surveys, trail cameras, and bud damage surveys were employed across 18 kiwifruit orchards in the Bay of Plenty, Aotearoa/New Zealand. House sparrows (Passer domesticus), chaffinches (Fringilla coelebs), and silvereyes (Zosterops lateralis) were identified as the most frequent species damaging buds. On average, 10% of buds were damaged, but rates of damage varied widely across orchards. Increasing availability of sward seeds was associated with increasing bird abundance but decreasing bud damage levels, potentially because seeds from sward vegetation offer an alternative food source. Shelterbelt volume, block management type (conventional vs organic), and the proportion of vegetation in the surrounding landscape also influenced bird abundance and damage. Understanding which management and environmental factors influence bird abundance and damage may benefit bird management in orchards, such as leaving swards unmown to increase sward seed availability and to reduce bird damage levels to kiwifruit buds.