The wildlife pet trade as a driver of introduction and establishment in alien birds in Taiwan

Abstract

The global trade in alien cage birds is flourishing and is considered to be one of the major routes by which species are entrained into the humanmediated invasion pathway. Here, we explore the likely influence of the wild bird trade on alien bird invasions in Taiwan. Specifically, we analyse the characteristics of alien bird species that have been successfully introduced and established at large in the wild. We use phylogenetic regression models to compare the traits of alien species recorded in the cage bird trade in Taiwan that have (or have not) subsequently been recorded at large in the wild, and the traits of species recorded in the wild that have (or have not) established (species identified in the Breeding Bird Survey in Taiwan). Alien species were more likely to be recorded as successfully introduced if they were commonly for sale in the Taiwanese pet bird trade, and possessed songs considered to be more attractive to people. Species that have been sold in the pet market for a longer period were also more likely to have been recorded in the wild. Establishment success was more likely for large-bodied bird species, but not strongly related to other predicted determinants of success, including proxies for propagule pressure and climate matching. We conclude that the pet trade influences bird invasions in Taiwan by determining which species are exposed to novel environments there, but which of those introduced species goes on to establish may depend more on their intrinsic life histories.

Geographical range expansion of alien birds and environmental matching

“…The three most likely models (M1-M3 with bracketed DAICc) included two predictor variables. Nevertheless, we found no effect of the number of birds for sale on alien range size in Taiwan (Su et al 2015a), unlike previous studies of alien birds and other species (Gammon & Maurer 2002, Liu et al 2014. Importance is the sum of the Akaike weights across all models including that variable.…”

“…Here, a variety of bird-related cultural activities, such as religious prayer animal release (animals are released for religious reasons, such as to accrue karma), bird contests (including singing competitions) and the keeping of cage-birds (including bird-walking, a social activity in which owners take their caged birds outdoors for fresh air), shape societal demands for bird species. Thus, the bird trade is an important source of introduced species, and at least 70% of introduced species, and 90% of established species, have been recorded in the bird markets in Taiwan (Su et al 2015a). Email: t.blackburn@ucl.ac.uk bird market in Taiwan (Su et al 2014) and to determine the characteristics of species that have the opportunity to establish alien populations there.…”

“…These demands interact with the availability of bird species in trade to shape the species composition of the pet *Corresponding author. as prayer animals) or escape if they are more frequently for sale in the Taiwanese pet bird trade and have been sold in the pet market for a longer period (Lee & Shieh 2005, Su et al 2015a. Thus, the bird trade is an important source of introduced species, and at least 70% of introduced species, and 90% of established species, have been recorded in the bird markets in Taiwan (Su et al 2015a).…”

“…Email: t.blackburn@ucl.ac.uk bird market in Taiwan (Su et al 2014) and to determine the characteristics of species that have the opportunity to establish alien populations there. Establishment success is more likely for large-bodied bird species but is not strongly related to other predicted determinants of success in Taiwan (Su et al 2015a). Bird species are more likely to be released (e.g.…”

Pet problems: Biological and economic factors that influence the release of alien reptiles and amphibians by pet owners

“…Despite the importance releases play in the invasion process for the pet trade pathway, most of the research to date has focused on the factors influencing the establishment of exotic pet populations and not on the factors related to their initial introduction (or release; Bomford, Kraus, Barry, & Lawrence, ; Fujisaki et al., ; Mahoney et al., ; Van Wilgen & Richardson, ). The few published studies on pet species release are lacking in both taxonomic and analytical breadth (e.g., Duggan, Rixon, & MacIsaac, ; García‐Díaz & Cassey, ; Su et al., ; Tingley et al., ). Consequently, the release stage is frequently ignored in risk assessment (Leung et al., ), even though there is considerable evidence that if alien species are not released, or are released in small enough numbers, they are far less likely to become established (Cassey, Delean, Lockwood, Sadowski, & Blackburn, ; Lockwood, Cassey, & Blackburn, ).…”