Not All Birds of the Same Feather: A Systematic Review of Ecosystem Services and Disservices in Horticulture

Wild birds can provide essential benefits and cause significant harm in food production systems, commonly framed as ecosystem services and disservices, respectively. We conducted a systematic review of the literature on avian ecosystem services and disservices in horticultural systems, analysing 251 studies published between 1912 and 2023. Species richness and abundance were the most commonly used metrics. A total of 128 studies investigated ecosystem services, 109 addressed disservices, and only 22 considered both. Pest control (137 occurrences) and crop damage (120) were the dominant subjects within ecosystem services and disservices, respectively. However, crop damage was frequently reported without assessment, suggesting a confirmation bias towards birds as pests. The methods used to assess services and disservices were diverse, including species identification, damage and yield surveys, landscape analysis, experiments, published data, social surveys, laboratory techniques, and economic or ecological modelling. Despite this methodological diversity, most studies used only one or two approaches. Studies incorporating human-wildlife conflict were rare, despite their relevance for both conservation and horticultural management. This review reveals a bias towards studying avian contributions that are more easily measurable, such as pest control and crop damage, while more complex or less visible effects, such as pollination, disease control, or herbivore release, remain underexplored. As a result, birds' roles in horticultural systems are often understood in fragmented terms, potentially leading to ineffective or unjustified management decisions. A more holistic, species-focused, and integrative approach is needed to fully understand the trade-offs between ecosystem services and disservices. Such understanding is critical not only for enhancing the sustainability and productivity of food systems, but also for conserving wild birds in increasingly intensified agricultural landscapes.