Temporal activity patterns of Common Bulbuls Pycnonotus barbatus in South African litchi orchards: implications for crop damage

Abstract

Frugivorous birds can cause substantial fruit losses in orchards, yet their role in South African litchi agroecosystems remains poorly understood. We investigated the seasonal, monthly and diel activity patterns of the Common Bulbul Pycnonotus barbatus across two commercial litchi farms in the Levubu region, Limpopo province. Daily detections were significantly higher during the ripening/harvest stage than during fruit set and flesh development, consistent with increased fruit availability. Activity also varied across phenological periods and months, peaking in December and remaining lower during pre-ripe stages, indicating distinct effects of crop phenology and fine-scale monthly variation in addition to broader seasonal influences. Within the diel cycle, detections were significantly higher in the late afternoon/evening, with no evidence of increased morning activity. Bulbul activity increased ∼70–80% during the harvest stage relative to earlier fruit production stages (e.g. fruit set, flesh development). These patterns highlight the species’ capacity to exploit peak fruit availability, with potential implications for orchard yield losses. This study provides the first quantitative assessment of Common Bulbul activity in South African litchi orchards and alludes to the importance of incorporating avian frugivory into crop protection and management strategies, although direct measures of crop damage were not assessed.