engleski

Factors affecting the goldcrest/firecrest abundance ratio in their area of sympatry

The goldcrest (Regulus regulus) and the firecrest (Regulus ignicapilla) are sympatric over a large part of Europe, but with different abundance ratios. We studied the effects of geographical location, vicinity of the species range boundaries, habitat and climate factors on the goldcrest/firecrest abundance ratio. At the continental scale, a weighted multiple linear regression model resulted in four significant covariates: temperature, precipitation, forest type and occurrence rate (representing the vicinity of the species’ range boundaries). The firecrest dominates in warmer and more humid areas and its dominance is more pronounced in mixed forests. The projection of the model showed that in any combination of temperature, precipitation and occurrence rate, the probability to encounter the goldcrest is higher in coniferous forests. Studies in Croatia and the Czech Republic showed regional differences in habitat preferences related to forest type. A significant effect of the seasonal dynamics of precipitation was confirmed in Croatia. Climate change and changes in forestry may influence the distribution and abundance of these two Regulus species in Europe.

Regulus; sympatry; climate

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