Two Barbados bird species have been shown to pass the popular animal cognition test of string-pulling.
String pulling was first described nearly two millennia ago by Pliny the Elder, who observed captive goldfinches pulling up small buckets of water. This skill is considered to be one of the most complex problem-solving tasks for animals, although it has been achieved by several birds, including some corvids and parrots.
Jean-Nicolas Audet and colleagues tested the string-pulling ability of wild-caught Carib grackles and Barbados bullfinches in a PLOS ONE study. As shown in this video, they suspended food by a string from a perch, placing it out of the birds’ reach inside a cylindrical container. The grackle in the video demonstrates the series of coordinated actions required to pull the string and retrieve the food.
Just two of the 31 grackles successfully retrieved the food, while 18 of the 42 bullfinches succeeded. When the authors tested the bullfinches on six other cognitive tasks, including general problem-solving ability, they found string-pulling performance to be unrelated to performance on any other test. They suggest that a number of skills, possibly including trial-and-error learning, may be involved in a bird’s string-pulling success.
Research Article: Audet J-N, Ducatez S, Lefebvre L (2016) Bajan Birds Pull Strings: Two Wild Antillean Species Enter the Select Club of String-Pullers. PLoS ONE 11(8): e0156112. doi:10.1371/journal.pone.0156112
Image and Video Credit: Audet et al. (2016)