Is the Pied Flycatcher Ficedula hypoleuca overcompeted by the Collared Flycatcher Ficedula albicollis in the natural forest of Bialowieza?

摘要

We studied the fluctuation in 1975-1997 numbers of two species: the Pied Flycatcher Ficedula hypoleuca and the Collared Flycatcher F. albkollis breeding in natural cavities in the primeval deciduous stands of the Bialowieza National Park (ME Poland). Both studied birds are commonly regarded as competitors if sympatric. Densities of two flycatchers are positively correlated within 7 plots (pooled data) investigated by a territory mapping method over 22 years (r = 0.71, p < 0.05) and 36 ha plot studied very intensively through 9 years (r = 0.35, p < 0.05). We found no evidence that the Pied Flycatcher density is negatively affected by the dominant Collared Flycatcher when that stronger species has a higher density. Clearly, both species fluctuated in a parallel way which contradicts an earlier generalization. The Pied Flycatcher breeds in Biatowieza deciduous stands in much lower densities than the Collared Flycatcher does.