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Acoustic discrimination of predators by black-capped chickadees (Poecile atricapillus)
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Smaller owls and hawks are high-threat predators to small songbirds, like chickadees, in comparison to larger avian predators
due to smaller raptors’ agility (Templeton et al. in Proc Natl Acad Sci 104:5479–5482, 2005). The current literature
focuses only on high- and low-threat predators. We propose that there may be a continuum in threat perception. In the current
study, we conducted an operant go/no-go experiment investigating black-capped chickadees’ acoustic discrimination of
predator threat. After obtaining eight hawk and eight owl species’ calls, we assigned each species as: (1) large, low-threat,
(2) mid-sized, unknown-threat and (3) small-, high-threat predators, according to wingspan and body size. Black-capped
chickadees were either trained to respond (‘go’) to high-threat predator calls or respond to low-threat predator calls. When
either low-threat predator calls were not reinforced or high-threat predator calls were not reinforced the birds were to withhold
responding (‘no-go’) to those stimuli. We then tested transfer of training with additional small and large predator calls,
as well as with the calls of several mid-sized predators. We confirmed that chickadees can discriminate between high- and
low-threat predator calls. We further investigated how chickadees categorize mid-sized species’ calls by assessing transfer
of training to previously non-differentially reinforced (i.e., pretraining) calls. Specifically, transfer test results suggest that
mid-sized broad-winged hawks were perceived to be of high threat whereas mid-sized short-eared owls were perceived to be
of low threat. However, mid-sized Cooper’s hawks and northern hawk owls were not significantly differentially responded
to, suggesting that they are of medium threat which supports the notion that perception of threat is along a continuum rather
than distinct categories of high or low threat. -
- Date created
- 2020-02-27
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- Subjects / Keywords
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- Type of Item
- Article (Published)