Ludwik Tomiałojć

The Breeding Bird Community of a Primaeval Temperate Forest (Białowieża National Park, Poland) at the End of the 20th Century

Abstract. The 1995–1999 results of the mapping technique censuses carried out in permanent plots situated in three types of old-growth primeval BNP stands (ash-alder riverine, oak-hornbeam, mixed coniferous) are presented and contrasted with the data gathered in the same plots in the late 1970s. Most community parameters, such as composition of breeding avifauna, species richness, make-up and cumulative proportion of dominants, remained basically unchanged. Only the overall bird density has increased considerably, by 13–38% in different plots. This has been due to parallel increases in numbers of several species, widely differing in their nesting sites, food requirements and migratory habits. As numbers increased simultaneously in all the plots, the density differences across habitats remained the same, from highest densities in riverine stands at the forest edge (up to 124 p/10 ha), through oak-hornbeam stands, to lowest in the coniferous stands (48–50 p/10 ha). Despite this differentiation the breeding avifauna in individual plots was quite similar (density similarity index exceeding 50% ), indicating that their breeding assemblages constituted samples from a single bird community. In most cases the numerical increases could not be attributed to changes in local environmental factors, such as food resources, weather conditions or changes in habitat structure. Only in the coniferous stands, could habitat changes leading to diversification of their structure (gap formation, increasing number of deciduous trees) have been responsible for increasing species richness and abundance there. The apparent lack of a relationship between changes in bird numbers and the local situation suggests that the factors acting on a larger scale (outside the study area) could have been involved. Despite the directional changes in bird abundance observed in the Białowieża Forest, its breeding bird assemblage, when compared with amplitude of changes recorded over the same period in other areas and habitats, stands out as an example of remarkable stability.

The Influence of Predators on Breeding Woodpigeons in London Parks

This London study emphasises the importance of predator pressure in controlling Woodpigeon numbers. In Britain Wood pigeons achieve higher densities in rural areas than in urban parks, though the reverse can apply in central Europe; and in both situations their numbers tend to be inversely related to the numbers of Carrion/Hooded Crows. which species emerges as one of the more serious predators.

Accuracy of the Mapping Technique for a Dense Breeding Population of the Hawfinch Coccothraustes coccothraustes in a Deciduous Forest

Abstract. The accuracy of the territory-mapping technique for estimating the abundance of densely breeding Hawfinches was tested in an old and unfragmented lime-oak-hornbeam forest in the Białowieża National Park, E Poland. Hawfinch numbers estimated from counts of the whole bird community carried out with the application of the standards of the improved mapping technique were compared with seven-year data on the birds true numbers, which are known from parallel intensive nest searches and persistent tracking of the movements of pairs. In a forest with a dense population of Hawfinches the mapping technique underestimated their numbers by 20% in years of moderate density and by 35% during high-density years. Even though the underestimation was negatively correlated with the true density of Hawfinches, the figures obtained by both methods reflected year-to-year changes in a similar way. An improvement in mapping data is achievable either by closer attention being paid to the species during standard visits (the best ones for surveying it), or post factum by the introduction of a correction factor into the mapping-technique figures.

Reproduction and Population Dynamics of Hawfinches Coccothraustes coccothraustes in the Primeval Forest of Białowieża National Park (NE Poland)

Abstract. The breeding performance of Hawfinches was studied during seven years (1991–98, except 1995) under conditions of an extensive close-to-pristine oak-lime-hornbeam forest in the Białowieża National Park, eastern Poland. Two 30–31.5 ha plots were regularly checked each year to find most nests present, usually observed since the period of their construction. Mean clutch size (5.27 ± 0.66, for best year — 5.5) finally produced small family size, owing to a partial loss, fledging and post-fledging mortality. Average breeding losses calculated traditional way were 72.8% (n = 202), mostly due to egg robbing, then predation on nestlings (three times less frequent), and, sporadically, adverse weather conditions at the moment of fledging. Nesting success (5.9–35.7%, 27.2% on average), strongly varying between years, is lower than in most Hawfinch populations from other (anthropogenic) habitats, being one of the lowest among temperate Passerines. In spite of low production of young the species remains numerous across deciduous stands of the Białowieża Forest, with its numbers even increasing since the 1980s. This large and dense population living in an apparently optimal habitat may, sporadically, be supported by influxes from other (anthropogenic?) sites.

Distribution, Breeding Density and Nest Sites of Hawfinches Coccothraustes coccothraustes in the Primeval Forest of Białowieża National Park

Abstract. Long-term observations (1991–2002) have shown that Hawfinches breed throughout the extensive Białowieża Forest; they are only slightly less numerous in the forest interior than at its edge. Population size, habitat and nest sites were studied in two plots in the species-optimal habitat (continuous oak-lime-hornbeam old-growth). The true breeding density there was 4.0–8.4, reaching as much as 15.2 p/10 ha in some years, while, according to the combined territory-mapping method for the same period, it was, on average, 5.8 pairs/10 ha in oak-lime-hornbeam, 3.3 pairs/10 ha in riparian ash-alder, but less than 0.5 pairs/10 ha in mixed coniferous-deciduous or young deciduous stands (marginal habitats for this species). Being among the most numerous species in the Białowieża Forest bird community, Hawfinches hold small nesting territories that are sometimes loosely grouped. Nests are built at an average height of 18.1 (7–34) m in the tree canopy. Hornbeams are the preferred tree species for nesting in the oak-lime-hornbeam stands (also clumps of mistletoe in the continental maple), while black alders in the riparian woodland. Originally, the Hawfinch must have been a species of old, high forests. Its recent nesting elsewhere — low in bushes or, preferably, along woodland edges — is likely to be a secondarily acquired trait; it could also be due to a bias — Hawfinch nests are more easily discovered in such localities.

Human Initiation of Synurbic Populations of Waterfowl, Raptors, Pigeons and Cage Birds

A common generalization is that wild birds somehow manage to colonize urban areas without human support, which is often true. This paper focuses on a different and probable, though not rare, course of events, when some urban bird populations emerge with immediate human support, by intentional introductions or escape from captivity. This alternate mechanism may be responsible for settling the very first colonizers directly into a strongly urbanized habitat. Such “pioneers” might later be followed by “surplus individuals” moving into cities from the neighbouring natural populations. Eventually, birds of local origin may constitute a prevailing part of the locally developed synurbic population, thus, overshadowing the early genetic contribution of the very first pioneers. Yet the latter individuals might be important as initiators of the colonization and geographical expansion of this process.

Song Thrush Turdus philomelos and Hawfinch Coccothraustes coccothraustes Exhibit Non-Random Nest Orientation in Dense Temperate Forest

Abstract. Patterns of bird nest orientation in dense forest interiors are relatively unknown. Using data collected in primeval temperate forests at the Białowieża National Park in Poland, we found that two arboreal nesting species, the Song Thrush Turdus philomelos and the Hawfinch Coccothraustes coccothraustes, located significantly more of their nests in the southern half of tree crowns than in the northern half. Nest orientation also depended on nest height: the higher Song Thrush and Hawfinch nests were in the crowns of trees, the stronger preference both species had for locating their nests toward the south. For the Song Thrush, tree species interacted with the date of clutch initiation to influence patterns of nest orientation: Song Thrushes located more of their nests on the ‘south-facing’ sides of live Norway Spruces Picea abies as the nesting season progressed. Spring temperature during the nest construction period affected Hawfinch nest orientation, with significantly more ‘south-facing’ nests during colder springs. The directional orientation patterns we observed may be viewed as a response of nesting birds to weather conditions during nest site selection and nest construction periods, when exposure to solar radiation could help regulate nest temperatures during cold mornings or days.