The Rooftop Raven Project: An Exploratory, Qualitative Study of Puzzle Solving Ability in Wild and Captive Ravens

摘要

The family Corivdae, which includes crows and ravens, contains arguably some of the most intelligent species the animal kingdom has to offer. Separated from primates by at least 252 million years of evolution, birds bear striking physiological differences from mammals, while displaying similar intellectual abilities. This apparent convergent evolution of intelligence sheds light on what could possibly be a universal phenomenon. While many excellent studies show the abilities of corvids, the majority of them test only captive subjects. This study tested the capabilities of both captive and wild ravens, from three different species. The first portion of the study tested which of the four solutions offered wild ravens would choose when solving a Multi-Access Box. The second portion of the study tested the performance of wild and captive ravens when solving a Multi-Latch Box. The nine raven subjects were split into four different levels of enculturation based on their known histories. Two wild common ravens (Corvus corax) on the campus of the University of Arizona were level 1, four wild common ravens in the parking lot of a United States Forest Service parking lot were level 2, two captive and trained Chihuahuan ravens (Corvus cryptoleucus) from the Raptor Free Flight program at the Arizona-Sonora Desert Museum comprised level 3, and one captive and trained white-necked raven (Corvus albicollis) made level 4. It is possible to run trials with completely wild and free birds. It was found that ravens prefer direct methods of obtaining food, such as opening doors and pulling strings, instead of tool use. It was also found that while the relationship between enculturation level and success solving a puzzle was not linear, captive birds were the best solvers. The data given here suggest that captivity, training and enrichment history, and enculturation should all be considered when performing cognitive studies with animals.