If you were starving and in danger of being attacked, would you stop eating and be more cautious if you heard or saw the potential attacker? Researchers at the University of Alberta tried to respond to this question by observing Black-capped Chickadees (Poecile atricapillus). They measured how they would react to different sources of information about the presence of a predator in terms of changing their feeding behavior during winter.
These birds are a model species, meaning that they are abundant, easily accessible, and used as a basis for scientific understanding for other species. They can give important insight about information theory, which is the study of how animals use information to make decisions. The main goal for this study was to determine how different sources of information, such as visual or acoustic cues, could inform the birds about the risk of predators in the surrounding area and exactly how these types of information affect their feeding behavior. Would the effect be greater when the cues are presented together than when presented separately? How would harsh winter conditions affect the degree of response?
To understand the chickadees’ responses to cues alerting them of predation risk, the researchers attached a unique identification chip to the leg of each bird to record the exact time, date, and number of times they visited the feeders that were set up for this experiment. The researchers placed feeders across the Devonian Botanical Garden near Edmonton, Canada, and presented fake mounts of predators and alarm calls of other chickadees to record the response to different combinations of cues about increased risk of predation.
The researchers predicted that seeing the predator (visual cue) would be the most reliable source of information and would produce a greater response in their behaviour, so the birds would take longer to return to the feeders after they were presented with the fake predator. There was a notable variation in the response from the birds, but effectively this predication turned out to be accurate. Chickadees took on average 52.6 minutes to return to the feeders after seeing the predator and only 37 minutes after just hearing alarm calls. The researchers also found that when the visual and acoustic cues were presented together, the response was the same as when only the visual cue was presented, meaning that there was a redundant response and no additional information to affect the response when given acoustic cues. This response, however, was not always the same and changed depending on the temperature of the day. On harsher winter days, this redundant effect disappeared, and chickadees responded more to a visual cue alone than the combination of cues.
The results from this study supported the idea that decision-making behavior for feeding in response to perceived danger is an ever-changing process and the response will vary depending on the context. If the day is too cold, it is more important to feed than to be cautious about potential predators, but it will depend on what type of information the birds are receiving. These results show how truly complex decision-making is in animal behavior; the ultimate choices that animals make depend on how reliable they perceive the information around them to be.
For more information:
Arteaga-Torres, J. D.1, Wijmenga, J. J.1, & Mathot, K. J.1,2 (2020). Visual cues of predation risk outweigh acoustic cues: a field experiment in black-capped chickadees. Proc. R. Soc. B, 287: 20202002. http://dx.doi.org/10.1098/rspb.2020.2002
1Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2R3
2Canada Research Chair in Integrative Ecology, University of Alberta, Edmonton, Alberta, Canada T6G 2R3
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[All images provided by Josue Arteaga-Torres; Edited by Lindsey Broadus]