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Effects of individual experience and habitat on the intensity of interspecific aggression in great spotted and middle spotted woodpeckers
MÁCA, Matěj
Woodpeckers represent an ideal model for studying competition in birds, due to their adaptation to foraging on tree trunks and nesting in tree cavities. The Great Spotted Woodpecker (Dendrocpos major) occupies a wide range of forest stands, while the Middle Spotted Woodpecker (Dendrocoptes medius) specializes on old deciduous trees. However, the Middle Spotted Woodpecker has recently become more wide spread, occupying new habitats. In my research, I compared the territorial behaviour of the Great Spotted Woodpecker in relation to the Middle Spotted Woodpecker in the Pelhřimov region, where the Middle Spotted Woodpecker has only recently started to occur and is very rare, with behaviour of the Great Spotted Woodpecker in the České Budějovice region, where both species have coexisted for several decades. In the territories of the Great Spotted Woodpecker, I used playback experiments to observe their reactions to the Middle Spotted Woodpecker, the Grey-headed woodpecker (Picus canus) and the Wood Warbler (Phylloscopus sibilatrix), which served as a control and no reactions was expected. Principal component analysis (PCA) was used to evaluate the behaviour. I also compared the representation of deciduous trees in the territories of both species. The PCA analysis showed a very strong intraspecific response of the Great Spotted Woodpecker in the Pelhřimov region, with the Great Spotted Woodpecker exhibiting all observed behaviour types. On the other hand, the response to the Middle Spotted Woodpecker was very low and did not differ much from that to the Grey-headed Woodpecker and the Wood Warbler. However, after comparing the reactions of Great spotted Woodpeckers from the Budějovice region, the reactions to the Middle Spotted Woodpecker in the Pelhřimov region were stronger. This result may suggest that in the Budějovice region both species passed segregation of ecological niches. Furthermore, the results showed that the Great Spotted Woodpecker in the Pelhřimov region spent more time in close proximity to the Middle Spotted Woodpecker mount if there was a higher proportion of deciduous trees in their territory, i.e. a suitable habitat for the Middle Spotted Woodpecker. This suggests that the Great Spotted Woodpecker from the Pelhřimov region may perceive that the Middle Spotted Woodpecker could compete with it in these habitats, and so it attempts to defend its territory.
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