Object categorization by wild ranging birds—Winter feeder experiments

Nováková, Nela; Veselý, Petr; Fuchs, Roman

doi:10.1016/j.beproc.2017.08.002

Cited by 7 publications

(2 citation statements)

References 43 publications

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“…Previous studies have shown that birds perceive models as live animals [ 36 , 37 ]. Specifically, starlings [ 37 ] perceive stuffed model of the same species as conspecifics and taxidermy mounts of raptors have been shown to elicit their antipredator behaviors [ 38 – 41 ]. Consequently, we believe we used a valid experimental manipulation.…”

Section: Methodsmentioning

confidence: 99%

European starlings use their acute vision to check on feline predators but not on conspecifics

Butler

Fernández‐Juricic

2018

PLoS ONE

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Head movements allow birds with laterally placed eyes to move their centers of acute vision around and align them with objects of interest. Consequently, head movements have been used as indicator of fixation behavior (where gaze is maintained). However, studies on head movement behavior have not elucidated the degree to which birds use high-acuity or low-acuity vision. We studied how European starlings (Sturnus vulgaris) used high-acuity vision in the early stages of visual exploration of a stuffed cat (common terrestrial predator), a taxidermy Cooper’s hawk (common aerial predator), and a stuffed study skin of a conspecific. We found that starlings tended to use their high acuity vision when looking at predators, particularly, the cat was above chance levels. However, when they viewed a conspecific, they used high acuity vision as expected by chance. We did not observe a preference for the left or right center of acute vision. Our findings suggest that starlings exposed to a predator (particularly cats) may employ selective attention by using high-acuity vision to obtain quickly detailed information useful for a potential escape, but exposed to a social context may use divided attention by allocating similar levels high- and low-quality vision to monitor both conspecifics and the rest of the environment.

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Section: Methodsmentioning

confidence: 99%

European starlings use their acute vision to check on feline predators but not on conspecifics

Butler

Fernández‐Juricic

2018

PLoS ONE

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“…In both experiments, the pigeon dummy led to a big drop in the number of birds visiting a feeder. Based on previous studies [ 12 , 13 , 15 , 40 , 41 ], we chose a pigeon as a harmless control of sparrowhawk size, but it was not perceived as such, that is, as harmless. Of course, pigeons are not predators, but they can act as potentially strong food competitors on the feeder.…”

Section: Discussionmentioning

confidence: 99%

Untrained birds’ ability to recognise predators with changed body size and colouration in a field experiment

2021

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Background During recognition process, multiple parameters of the encountered stimulus may play a role. Previous studies with wild birds identified the importance of several salient features (e.g., eyes, beak, prominent elements of colouration) which birds use to recognise other bird species, such as predators or nest parasites. In the present study, we observed the responses of passerines visiting winter feeders to stimuli in the form of dummies of Eurasian sparrowhawk which were modified in body size and/or colouration but always carried the salient features of raptors (hooked beak, talons) and one species-specific feature of the sparrowhawk (yellow eyes). In the vicinity of a feeder, we placed a dummy of an unmodified sparrowhawk, life-sized sparrowhawk with pigeon, great tit, or robin colouration, a small, great tit-sized sparrowhawk dummy with unmodified or pigeon colouration, or an unmodified pigeon dummy, which functioned as a harmless control. Then we measured how it affected the number of visits. Results We found that birds were less afraid of small dummies regardless of their colouration than they were of life-sized raptor dummies or even the pigeon dummy. This contrasts with the results of a previous laboratory experiment where great tits’ reaction to small dummies was comparably fearful to their response to life-size dummies. In our experiment, birds were also not afraid of life-sized dummies with modified colouration except for a robin-coloured dummy, which caused an equally significant fear reaction as an unmodified sparrowhawk dummy. It is likely that this dummy resembled the colouration of a male sparrowhawk closely enough to cause this effect. Conclusions Based on our observations, we conclude that birds use contextual features to evaluate the size of other birds. Distance and familiar reference points seem to play an important part in this process.

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