Use of slope and feature cues in pigeon (Columba livia) goal-searching behavior
Journal of Comparative Psychology (2012) - Comment
pubmed: 22390622  doi: 10.1037/a0026900  issn: 1939-2087  issn: 0735-7036 

Daniele Nardi, Roseanne J. Mauch, Diana B. Klimas, Verner P. Bingman