Reese, L., Ladwig-Wiegard, M., von Fersen, L. et al. 2020. Deflighting zoo birds and its welfare considerations. Animal Welfare 29(1), 69-80.

For over a century, the practice of deflighting has taken place in zoological collections in order to ensure birds remain in open-topped enclosures. Over time, efforts have been made to improve or develop new (surgical) techniques, reduce risk of complications during deflighting and minimise stress and pain during the procedure. However, increased public interest in issues of animal welfare has coincided with a questioning of the practice of removing a bird's ability to fly. The ensuing debate, which continues to progress among a variety of differing stakeholders, has led to various legislative adjustments across a number of countries. Despite significant legislation, the dialogue has been both subjective and highly emotive. A plethora of opinions exist as to why deflighting should be outlawed, why it is necessary, or how it has the potential to improve a bird's living conditions. However, most are based on assumption or issues unrelated to welfare. To the authors' knowledge, to date, no scientific data have been published on the welfare implications of deflighting for the commonly deflighted bird species, such as waterfowl, flamingos (Phoenicopteridae), pelicans (Pelecanidae), storks (Ciconiidae), cranes (Gruidae) and herons (Ardeidae). The aim of this study is to present an overview of the relevance of deflighting to zoo husbandry, the species primarily affected, the techniques currently in use, the legality in differing countries and the extent of scientific knowledge as regards potential ethological and welfare concerns. An urgent need for evidence-based studies is highlighted, to further inform this practice at a species-specific level.