Predator recognition is essential for prey survival, allowing for appropriate antipredator strategies. Some bird species, such as the red-backed shrike (Lanius collurio), distinguish not only between predators and non-threatening species but also between different predator species. Earlier studies have identified general predator "key features", especially beak shape and talons, as critical for predator recognition. The question, though, still remains of whether exchanging predator key features with those of nonpredatory species or, alternatively, completely removing them, have different or equal impact on recognition. Here we tested to ascertain whether the presence of the "incorrect key features" of a harmless pigeon (Columba livia) placed on a common kestrel (Falco tinnunculus) body impairs predator recognition more efficiently than the absence of any key features. We presented an unmodified kestrel dummy and two modified kestrel dummies (one with pigeon key features, the other lacking key features) to wild red-backed shrikes defending their nest. The shrikes attacked the unmodified dummy kestrel more intensively than both kestrel modifications when defending the nest. However, shrikes did not show different responses to the kestrel with pigeon key features and the featureless kestrel. Our findings show that the absence and exchange of key features have the same effect in this case. These results are discussed in the context of recognition of a specific predator species and predators as a category in general.

• Klíčová slova
• Lanius collurio, Antipredator behaviour, Categorization, Mobbing, Predator–prey interactions, Recognition,
• MeSH
• Columbidae * fyziologie   MeSH
• Falconiformes * fyziologie   MeSH
• predátorské chování * MeSH
• rozpoznávání (psychologie) * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The red-backed shrike (Lanius collurio) used to be one of the most common hosts of the common cuckoo (Cuculus canorus). Nevertheless, during the last 30 years, there is increasing evidence from Central Europe that the occurrence of cuckoo chicks in shrike nests has become scarcer, and that in some locations they have disappeared completely. Multiple hypotheses have been suggested to explain this abandonment. Here, we test the hypothesis that shrikes vigorously attack adult cuckoos, potentially resulting in ineffective parasitism. Adult common cuckoos resemble in appearance the Eurasian sparrowhawk (Accipiter nisus), a common predator of small passerines. One hypothesis presumes that the cuckoo has evolved this mimicry to avoid attack by small passerines when searching for their nests. Our results show that shrikes defending their nests attacked cuckoos very vigorously, more often, and more intensively than they did sparrowhawks. In the presence of a sparrowhawk dummy, parent shrikes only produced alarm calls and flew over the dummy. This suggests that cuckoo-hawk mimicry is ineffective in the case of shrikes and that they attack them much more often than they do any other presented intruder. Therefore, this activity could possibly result in the abandonment of shrikes as potential hosts for cuckoos.

• Klíčová slova
• brood parasitism, cuckoo–hawk mimicry, nest defense, red‐backed shrike,
• Publikační typ
• časopisecké články MeSH

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.

• Klíčová slova
• Birds, Body size, Colouration, Predator recognition,
• MeSH
• divoká zvířata MeSH
• Passeriformes * MeSH
• rozpoznávání (psychologie) MeSH
• velikost těla MeSH
• zpěvní ptáci * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH