2017

Josef Beneš, Petr Veselý

DOI: 10.1016/j.zool.2017.05.010

Abstract:

Birds are usually considered the main predators shaping the evolution of aposematic signals and mimicry. Nevertheless, some lizards also represent predominately visually oriented predators, so they may also play an important role in the evolution of aposematism. Despite this fact, experimental evidence regarding the responses of lizards to aposematic prey is very poor compared to such evidence in birds. Lizards possess very similar sensory and cognitive abilities to those of birds and their response to aposematic prey may thus be affected by very similar processes. We investigated the reactions of a lizard, the Gran Canaria skink (Chalcides sexlineatus), to an aposematic prey and its artificial Batesian mimic. Further, we attempted to ascertain whether the lizard’s food experience has any effect on its ability to recognise an artificial Batesian mimic, by using two groups of predators differing in their prior experience with the prey from which the mimic was fabricated. The red firebug (Pyrrhocoris apterus) was used as an aposematic model, and the Guyana spotted roach (Blaptica dubia) as the palatable prey from which the mimic was fabricated. The appearance of the roach was modified by a paper sticker placed on its back. The skinks showed a strong aversion towards the model firebug. They also avoided attacking the cockroaches with the firebug pattern sticker. This suggests that a visual rather than a chemical signal is responsible for this aversion. The protection provided by the firebug sticker was even effective when the skinks were familiar with unmodified cockroaches (previous food experience).

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2016

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

DOI: 10.1007/s11252-016-0558-9

Abstract:

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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2014

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

DOI: 10.1111/eea.12176

Abstract:

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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2014

Alena Cibulková, Petr Veselý, Roman Fuchs

DOI: 10.1007/s10682-014-9690-2

Abstract:

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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2016

Zuzana Karlíková, Petr Veselý, Jana Beránková, Roman Fuchs

DOI: 10.1111/eth.12454

Abstract:

Numerous studies have shown warning coloration to facilitate the discrimination of edible and inedible prey. However, inedible insect species may possess cryptic coloration as well. It has been shown that some other visual features (especially characteristic body shape) are sufficient for the recognition of some insect taxa (e.g. ladybirds, ants, wasps). We tested the ability of wild-caught great tits (Parus major) to discriminate between the identically coloured edible (roach – Blaptica dubia) and the inedible (firebug – Pyrrhocoris apterus) as prey according to subtle peripheral visual traits (shape of legs and antennae, body posture, and means of locomotion). Both prey species were offered either simultaneously or alternately. The ability of the birds to learn was tested by means of fourteen trial repetitions in two sessions. In general, great tits were not able to learn to discriminate between firebugs and roaches by subtle shape cues alone during the two sessions. However, multivariate analysis of individual bird behaviour showed that they adopted one of three different attitudes to the presented prey. Most of the birds never attacked any or always attacked both prey. In addition, a small proportion of the birds was able to discriminate between the two prey types and attacked only roaches. Nevertheless, firebugs survived most of the attacks, which suggests that in case of chemically protected prey, the evolution of conspicuous coloration is not always the best/only option.

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