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Morphological resemblance of the common cuckoo Cuculus canorus to the Eurasian sparrowhawk Accipiter nisus has been regarded as an example of predator mimicry. Common hosts could distinguish parasites as the result of coevolution, while rare hosts or nonhosts may mistake cuckoos for hawks because rare hosts or non-hosts behave similarly when faced with these two species. Birds usually produce alarm calls in addition to showing behavioral responses when in danger. However, previous studies of identification by rare hosts or non-hosts of sparrowhawks usually lacked experimental evidence of alarm calls. Great tits Parus major, a rare cuckoo host, perform similar behaviors and usually produce alarm calls in response to sparrowhawks and common cuckoos. Here, we tested whether great tits could distinguish common cuckoo from sparrowhawk based on analysis of their alarm calls and the effects of playback of alarm calls on conspecific behavior. Previous studies showed that great tits have a complex communication system that conveys information about predators, and they could perform different kinds of response behavior to different alarm calls. If great tits have not made the ability to distinguish between common cuckoo and sparrowhawk, then their acoustic responses to these two species and their response behaviors in playback experiments should be similar. Specimens of a common cuckoo (parasite), a sparrowhawk (predator) and an Oriental turtle dove Streptopelia orientalis (harmless control) were used to elicit and subsequently record the response behavior and alarm calls of great tits. There was no significant difference in behavioral response among great tits when exposed to the dummy of cuckoo, sparrowhawk and dove. In contrast, they differed significantly in alarm calls. Great tits produced more notes per call that contained increasing D-type and decreasing I-type notes when responding to sparrowhawk as compared to cuckoo or dove. In playback experiments, we found that great tits responded more strongly to great tit hawk than to great tit cuckoo or great tit dove alarm calls. Our study suggests that great tits are able to distinguish sparrowhawks from common cuckoos and convey relevant information in alarm calls by adjusting the number and combinations of notes of a single call type. K E Y W O R D Salarm call, cuckoo-hawk mimicry, great tit, parasite, playback, predator This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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In common with human speech, song is culturally inherited in oscine passerine birds ('songbirds'). Intraspecific divergence in birdsong, such as development of local dialects, might be an important early step in the speciation process. It is therefore vital to understand how songs diverge, especially in founding populations. The northward expansion of the Light-vented Bulbul Pycnonotus sinensis (J. F. Gmelin, 1789) into north China in the last 30 years provides an excellent opportunity to study birdsong evolution. We compared~4400 songs from newly established northern populations with~2900 songs from southern populations to evaluate song divergence after recent expansion. The total pool of syllables and especially song types was considerably smaller in the north than in the south, indicating 'founder effects' in the new population. The ancestral pattern of mosaic song dialects changed into a pattern of wide geographical sharing of a few song types and syllables, likely the result of fewer geographical barriers to 'meme flow', and the recent spread across a large area in the north. Our results suggest that song evolution and vocal trait shifts can arise rapidly after range expansion, and that in the Light-vented Bulbul 'founder effects', geographical isolation, and recent rapid expansions played important roles in the evolution of song dialects.

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Birdsong can act as a premating barrier to gene flow through its role in mate attraction and territorial defence. The link between geographic variation in song structure and ecological factors is key to the process of acoustically guided population divergence and isolation. Migratory behaviour is an example of such an ecological factor. In this study, we asked whether latitude and climate can explain song variation among migratory and sedentary populations of the marsh grassbird (Locustella pryeri sinensis), a rare songbird endemic of wetlands of eastern and northeastern China. We investigated two structurally different song parts: a repeating trill part followed by a more variable warble part. We found significant variation in acoustic structure and distinct divergence patterns between the two song parts across a latitudinal gradient and strong acoustic correlations with several bioclimatic variables. The trill part showed an increase in maximum frequency with latitude and the warble part became longer with fewer element types towards three higher latitude, migratory populations. These patterns are in line with a dual function of both song parts, increased sexual selection pressure at higher latitude and a complex impact of climate on song through vegetation and weather conditions.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Background & Aim: Nesting behavior is important for birds because this stage is critical for breeding success. Since urbanization is expanding worldwide, birds living in cities face huge challenges but the urban environment can also provide living opportunities. This review summarizes bird nesting behaviors in cities, analyzing the influence of factors such as climate, food resources, nest site availability, predation pressure, pollution, and anthropogenic disturbance on bird nesting based on publications in Biblioshiny programme. Summary: This study demonstrates that urbanization influences bird nesting period, nest site and nest material selection significantly, and that spatio-temporal nesting ranges and nesting materials differ between urban and rural birds. We highlight the need to evaluate whether city birds are well adapted or negatively affected by urbanization, which would require specific analysis of target populations and habitat conditions. Perspectives: We should propose effective and specific suggestions to protect city birds during urbanization based on •综述•