Archiv rubriky: Publikace

Birds at the winter feeder do not recognize an artificially coloured predator

Publikováno | Autor:

2016

Petr Veselý, Markéta Buršíková, Roman Fuchs

DOI: 10.1111/eth.12565

Pro ptáky a vůbec pro všechny, kdo hrají roli kořisti, je doslova životně důležité včas rozpoznat přítomnost predátora. Komu se to nepovede, tak už obvykle nedostane příležitost k opravnému pokusu. Pokud jde o ptáky, odborníci se domnívají, že rozeznávají predátory i pomocí jejich zbarvení. Skutečná role zbarvení v rozeznávání predátorů, ale stále zůstává tajemstvím. Čtěte více na webu PřF JU.

Abstrakt:

It is supposed that coloration may affect the recognition of predators by prey species; nevertheless, the significance of the coloration and its particular components in the recognition process remains unknown. We presented dummies of the European sparrowhawk (Accipiter nisus) with changed body coloration, but with all other typical features preserved (body size and shape, beak, eyes, legs), to great tits (Parus major) and blue tits (Cyanistes caeruleus) visiting a winter feeder. A pigeon (Columba livia f. domestica) dummy was used as a harmless control. Neither tit species showed passive avoidance in the presence of a dummy with an artificial, violet-white chequered coloration. They obviously did not consider such an object to be a predator despite the presence of the raptor beak, eyes and talons. Sparrowhawk dummies with the coloration completely changed (altered with those of a harmless European robin) or with the typical colour feature removed (barred pattern on the underparts) were considered to be as dangerous as the unmodified sparrowhawk. We discuss the possibility that the effect of salient raptor-like features such as beak shape, eye coloration, and leg and talons shape overwhelmed the effect of body coloration in these cases. Birds visiting the feeder probably were able to generalize the vigilance towards the sparrowhawk to other realistically coloured dummies, but not to the non-natural dummy.

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Disentangling the influences of habitat availability, heterogeneity and spatial position on the species richness and rarity of urban bird communities in a central European city

Publikováno | Autor:

2016

Michal Ferenc, Ondřej Sedláček, Jindra Mourková, Alice Exnerová, Jaroslav Škopek, Jiří Formánek, Roman Fuchs

DOI: 10.1007/s11252-016-0558-9

Abstrakt:

The prominent role of the absolute amount of (semi)natural habitats on urban avifauna richness is well documented; however the relative role of habitat availability, heterogeneity and spatial position at the scale of a whole city has not been investigated so far. The main objective of this study was to evaluate the relative influence of these variables on the species richness and rarity value of bird communities in the city of Prague, Czech Republic. We used three modes to describe the urban environment, resulting in different habitat category resolutions. Coarse habitat descriptors were good enough for predicting species richness, but a more detailed resolution was better in explaining the distribution of communities comprising rarer species. The availability of wooded habitats was consistently the most important variable explaining both richness and rarity of bird communities. Habitat heterogeneity enhanced species richness, especially in highly urbanized areas where wooded habitats were scarce. However, rarer species responded to habitat heterogeneity only weakly. The influence of grid cell spatial position on bird community richness was overridden by the impacts of habitat availability and heterogeneity. However, communities comprising rarer species tended to breed at peripheral sites encompassing open habitats and large woodlands. The preservation of sufficient wooded habitats including small patches remains the key tool for bird conservation in cities, and habitat heterogeneity should be supported in areas with less than ca. 3 % of wooded habitats. Rarer species benefit from the maintenance of more extensive patches of greenery in peripheral urban areas.

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Responses of urban crows to con- and hetero-specific alarm calls in predator and non-predator zoo enclosures

Publikováno | Autor:

2017

Kateřina Bílá, Jana Beránková, Petr Veselý, Thomas Bugnyar, Christine Schwab

DOI: 10.1007/s10071-016-1047-5

Abstrakt:

Urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. Predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. It can also occur when species do not form flocks but co-occur together. In this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, Corvus monedula) differently in a predator and a non-predator context with partly novel and unfamiliar zoo animal species. Birds were tested at the Tiergarten Schönbrunn in the city of Vienna by playing back con- and hetero-specific alarm calls and control stimuli (great tit song and no stimuli) at predator (wolf, polar bear) and non-predator (eland antelope and cranes, peccaries) enclosures. We recorded responses of crows as the percentage of birds flying away after hearing the playback (out of those present before the playback) and as the number of vocalizations given by the present birds. A significantly higher percentage of crows flew away after hearing either con- or hetero-specific alarm calls, but it did not significantly differ between the predator and the non-predator context. Crows treated jackdaw calls just as crow calls, indicating that they make proper use of hetero-specific alarm calls. Responding similarly in both contexts may suggest that the crows were uncertain about the threat a particular zoo animal represents and were generally cautious. In the predator context, however, a high percentage of crows also flew away upon hearing the great tit control song which suggests that they may still evaluate those species which occasionally killed crows as more dangerous and respond to any conspicuous sound.

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Visual warning signals of the ladybird Harmonia axyridis: the avian predators’ point of view

Publikováno | Autor:

2014

Alexandra Průchová, Oldřich Nedvěd, Petr Veselý, Bára Ernestová, Roman Fuchs

DOI: 10.1111/eea.12176

Abstrakt: Previous studies have suggested that spotted patterns are important in the protection of ladybirds against attack by avian predators. Nevertheless, these studies were based on the comparison of several ladybird species differing in colouration, but also in other traits (e.g., chemical protection). We presented natural as well as artificial colour modifications (using brown, red, and black paint) of the ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) – an invasive alien species for Europe – to an avian predator, the great tit, Parus major L. (Passeriformes: Paridae). All forms were considered to be equal in size, but differed in colouration and in the presence of spots. The chemical protection was equal except for one form. The birds displayed strong avoidance of all forms with red and black colouration; beetles with artificially removed red colouration (painted brown) were attacked more often. The beetles painted brown with black spots were slightly better protected than the painted beetles without spots. We can sum up that spots are of some importance in the protection of ladybirds; nevertheless, red and black colouration is the main part of the visual signal.

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Importance of conspicuous colours in warning signals: the great tit’s (Parus major) point of view

Publikováno | Autor:

2014

Alena Cibulková, Petr Veselý, Roman Fuchs

DOI: 10.1007/s10682-014-9690-2

Abstrakt: Few studies have dealt with the importance of colours per se in warning signalling, with the use of a broader array of different colours. We tested the reactions of great tits (Parus major) to colour modifications (red, orange, yellow, white, blue, violet, and green) of the warning signal of the red firebug (Pyrrhocoris apterus), preserving its typical black pattern. We used the edible Guyana spotted roach (Blaptica dubia) as the prey, each of which carried a paper sticker shield of a particular colour on its back. With such prey, the effects of the other traits of the red firebug (e.g. shape of the legs and antennae or chemical signals) on the birds’ reactions were removed. All of the conspicuous forms of the prey, possessing a black pattern, were protected against great tits better than the non-patterned brown control form. The level of protection decreased from those forms with colours similar to the model and commonly occurring in warning signals in nature (red, orange, yellow), through other conspicuous colours rarely occurring in warning signals in nature (white, violet, blue), to the colour which usually occurs as cryptic in nature (green). In the green form, repeated encounters were necessary to reach avoidance. Avoidance learning came to pass despite the fact that the presented prey was neither inedible nor distasteful.

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