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Contributed Talk

Session: : Behavior 2

COS 95-1 - Lack of color constancy hinders egg recognition in a wild bird

Tuesday, August 8, 2023
1:30 PM – 1:45 PM PDT
Location: B112
Abstract: Accurately perceiving visual cues is crucial for decision-making in wild animals. Although variation in light can impact color perception, it is generally assumed that birds compensate for variable light conditions through color constancy. Unfortunately, few studies have tested color constancy in wild birds. Here, we used an egg rejection experiment to test whether or not natural light conditions influence color perception and rejection behavior of the gray catbird (Dumetella carolinensis). Specifically, we experimentally parasitized catbird nests with egg models and recorded whether the host accepted or rejected these eggs. We measured the reflectance of each host and model egg as well as the irradiance at each nest, which allowed us to calculate the perceived difference in color between the host and model eggs when viewed under the nest’s specific light conditions. We hypothesize that catbirds have color constancy and therefore expect that the color of ambient light will not affect how they perceive and respond to colors; rather, rejection will be predicted by the perceived color difference between the host and model egg. However, if catbirds actually lack color constancy, their response to the egg models would be affected by the color of ambient light. Contrary to our expectations, we found the catbirds rejected model eggs more often when viewed under greener light, rather than correcting for their nest’s light condition. These findings strongly suggest that catbirds lack color constancy, because their responses were directly related to the color of light. This discovery indicates that nest light conditions may play a vital, and as of yet underappreciated, role in coevolutionary dynamics between hosts and parasites.