By Ryan Almeida, Alex Mazza, and Julie Lockwood.
In virtually every region of the world, songbirds are traded and kept as pets. As with any product, the reasons people choose to buy and sell songbirds are complex, and vary from person to person. However, we know that one nearly universal driver of the songbird trade, especially compared to other types of wildlife trade, is consumers’ desire to own animals with striking aesthetic traits. Birds with unique coloration or distinctive beaks are often a hot commodity among bird owners, and in certain regions, songbirds are kept not just as pets, but for use in singing competitions, making songbirds that can produce an attractive song highly desirable. While many of these songbirds are captive bred, traders source a substantial portion from the wild. For some of these wild-caught songbirds, high enough demand for certain traits can pose a significant risk of population decline or extinction.
In these cases of unsustainable trade, it is important to identify which ecosystem processes, such as pollination or seed dispersal, are disrupted by losing these species. At face value, traits such as color or singing ability may seem unrelated to the role songbirds play in supporting well-functioning ecosystems. However, all biological traits, regardless of whether they are aesthetic or functional, are the result of natural selection. Species that share aesthetic characteristics, such as unique coloration, often also play similar roles in their ecosystems, since those species may be closely related or have faced similar ecological pressures throughout their evolutionary history. As a result, high demand for species with particular aesthetic traits could result in a significant disruption to seemingly unrelated ecosystem processes.
Using a global database on songbird traits and trade, we set out to determine whether there is any evidence of these “linkages” between aesthetic traits that people desire and functional traits. We found that several aesthetic traits were strongly associated with certain ecosystem processes, and that the trade disproportionately threatens certain ecosystem processes. Fruit-eating, in particular, was highly associated with desirable traits, and was also highly prevalent among overexploited songbirds.
These findings provide a roadmap for understanding how people’s preference for traits in individual animals can have cascading effects on entire ecosystems. Further, while we focused on songbirds, this approach may be broadly applicable to any exploited species for which there is significant demand for particular traits.
Relational Thinking 