North American river otters (Lontra canadensis) discriminate between 2D objects varying in shape and color

Abstract

We investigated the ability of North American river otters (Lontra canadensis) to visually discriminate between 2D objects. The otters learned to discriminate between stimuli using multiple visual features and then were tested with stimuli in which one of the features was eliminated (color or shape). Two adult otters were trained in a two-alternative forced choice task to discriminate between a red circle and a blue triangle. Test sessions included probe trials containing novel shapes, colors, or shape-color combinations. Both otters successfully learned to discriminate between stimuli varying in multiple features. One of the otters was able to successfully discriminate between novel test stimuli when either color or shape were eliminated as salient features. This study was the first to explore the ability of L. canadensis to use different visual features to recognize objects and provides some preliminary evidence for color vision in this species. This research adds to the sparse literature on perceptual and cognitive capabilities in otters and can be used to support future conservation efforts for this species.

ゼニガタアザラシ(<i>Phoca vitulina</i>)の視覚的物体認知に関する研究：形状と明度のどちらを優位に使用して物体を弁別しているのか

“…In this study, we found that harbor seals discriminate between objects using the visual features of shape rather than brightness, at least for the objects we used in the experiment. This result differs from those of previous studies involving other terrestrial species (Elmore et al 2009, Gosset and Roeder 2000, Lucon-Xiccato et al 2019, Minini and Jeffery 2006, DeLong et al 2019. For terrestrial species, color or brightness difference is a significantly important parameter for foraging and avoiding predators (Bacon and Bugrhardt 1976).…”

Investigating Object Recognition Memory Using Sensory Enrichment with a North American River Otter (Lontra canadensis)

“…The otters were often motivated to participate in this cognitive task even when it could be quite challenging for the otters to learn a conceptual rule. For example, although one otter's performance was not significantly different than chance during the first test of the second experiment [20], the otter would still readily participate on every trial (performance on later tests was approximately 70% correct, with the other otter achieving approximately 80% correct in the first experiment). In addition to these cognitive tasks being enriching for the animal subject, it also allows researchers to learn more about the cognitive and perceptual abilities of many understudied species that are kept in zoos.…”

“…The animal must use their cognitive skills to engage in the task they are participating in, which could be classified as cognitive enrichment [3]. Two studies used a two-alternative forced-choice task to study the perceptual and cognitive abilities of North American river otters [20,21]. In this task, the otter is trained to choose between two different visual stimuli on each trial.…”

“…In addition to these cognitive tasks being enriching for the animal subject, it also allows researchers to learn more about the cognitive and perceptual abilities of many understudied species that are kept in zoos. For example, DeLong et al [20] found preliminary evidence of categorization (the ability to group objects together based on defining features) in North American river otters. These scientific findings can in turn be applied to aid in creating better enrichment initiatives for the species studied across many zoos.…”

“…Svoke et al [32] suggests that Asian small-clawed otters likely have dichromatic vision as well. Additionally, DeLong et al [21] found preliminary evidence of dichromatic vision in North American river otters, though further research is necessary.…”