Ecological specialization provides information about adaptations of species to their environment. However, identification of traits representing the relevant dimensions of ecological space remains challenging. Here we endeavoured to explain how complex habitat specializations relate to various ecological traits of European birds. We employed phylogenetic generalized least squares and information theoretic approach statistically controlling for differences in geographic range size among species. Habitat specialists had narrower diet niche, wider climatic niche, higher wing length/tail length ratio and migrated on shorter distances than habitat generalists. Our results support an expected positive link between habitat and diet niche breadth estimates, however a negative relationship between habitat and climate niche breadths is surprising. It implies that habitat specialists occur mostly in spatially restricted environments with high climatic variability such as mountain areas. This, however, complicates our understanding of predicted impacts of climatic changes on avian geographical distributions. Our results further corroborate that habitat specialization reflects occupation of morphological space, when specialists depend more on manoeuvrability of the flight and are thus more closely associated to open habitats than habitat generalists. Finally, our results indicate that long distance movements might hamper narrow habitat preferences. In conclusion, we have shown that species’ distributions across habitats are informative about their positions along other axes of ecological space and can explain states of particular functional traits, however, our results also reveal that the links between different niche estimates cannot be always straightforwardly predicted.

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The influence of arthropod availability on the formation of male little bustard breeding territories in central Spain was studied in two consecutive years. Arthropods (68,217 individuals) were sampled using pitfall trapping and male territories estimated by means of kernel functions. Hymenopterans (ants), beetles, mites and spiders were the main taxa found in the samples, while the highest contributions in terms of biomass came from hymenopterans, beetles and orthopterans. The only group that exhibited significant biomass differences between territory and non-territory locations was that of the beetles; this pattern was consistent between years. Carabidae was the main beetle family in terms of biomass, followed by other large beetles such as Tenebrionidae, Cleridae, Scarabeidae and Elateridae. The biomass of Carabidae that were larger than 15 mm was significantly higher within territories than outside them. The biomass of Cleridae was greater in fallows, while Elateridae were more abundant in arable fields. The total biomass of beetles that were larger than 15 mm was higher in arable fields than in fallows. Family richness differed between years, while diversity showed differences between agricultural fields (it was highest in fallows), although these variables did not differ between territory and non-territory locations. Results indicate that large beetles (particularly carabids) seem to be a valuable food resource that is defended by little bustard males during the highly energy-demanding breeding season, which is discussed here in relation to habitat selection, the mating system and its implications for the conservation of the species.

The analysis of a local community of forest passerines (13 species) using phylogenetic contrasts shows a correlation between body size of bird species and mean prey size, minimum prey size, maximum prey size and the size range of dietary items. This suggests that larger birds drop small prey taxa from their prey list, because of the difficulty of capturing very small prey, for energetic reasons or because of microhabitat usage. We find some support for the third hypothesis. Dietary niche breadth calculated across prey taxa is not related to body size. Dietary niche breadth, however, is correlated with size-corrected measurements of the bill and locomotor apparatus. Long and slender bills increase the dietary niche breadth. Thus subtle differences constrain foraging and the techniques of extracting certain prey taxa form crevices. Dietary niche breadth and foraging diversity are positively correlated with population density: at least locally dietary generalists occur at higher breeding densities than specialists.

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We studied year-round food preferences of the three-toed woodpecker (Picoides tridactylus) from 1994 to 2000 in Berchtesgaden National Park, Germany. We color-banded 52 birds for individual recognition, and we radiomarked 25 adults from this sample. We analyzed 142 feces of 30 adults and 588 feces of 40 nestlings from 15 nests. Additionally, we took samples from 20 trees recently used for foraging in 10 woodpecker territories to estimate local prey availability. Based on relative abundance and relative frequency of food items (i.e., importance value), overall diet composition of adult three-toed woodpeckers was dominated by spiders (Araneidea), larvae of longhorn beetles (Coleoptera, Cerambycidae), and bark beetles (Coleoptera, Scolytidae). Adults ate longhorn beetle larvae primarily during nesting, while imagines (fully developed adults) and larvae of various bark beetles appeared to be the main food resource outside the nesting season. Nestling diet was dominated by spiders and longhorn beetle larvae that were gathered 247 ± 122 m (x -± SD) from the nest. Our results demonstrated that consumption of bark beetles by three-toed woodpeckers varies throughout the year, being lowest during the nesting season, while longhorn beetle larvae are preferred throughout the year. Securing habitat requirements of both bark and wood-boring beetle communities is a critical step to maintaining viable three-toed woodpecker populations. JOURNAL OF WILDLIFE MANAGEMENT 68(3):683-693

For the assessment of the habitat use of bats with consideration of a complexity of environmental features a largescale multivariate canonical correspondence analysis (CCA) was performed. Data were collected in April-September (1999 using mist-netting and bat-detectors (n ¼ 209 samplings) in Slovakia (n ¼ 160 sites). For the habitat description, 17 environmental variables that characterised the sampling site, tree-species composition and general character of surrounding forest were selected. In study sites, altogether 93% of Slovak chiropterofauna species were recorded but only 16 species (2466 individuals) were recorded in more than 5% of samplings. The most common and frequent species were Myotis mystacinus (frequency of occurrence ¼ 57%, species dominance ¼ 12%) and Myotis myotis (44%, 10%), followed by Barbastella barbastellus (32%, 6%), Plecotus auritus (32%, 6%), Nyctalus noctula (31%, 9%) and Myotis brandtii (31%, 7%). Of the tested environmental variables used in CCA analysis, 13 had significant influence on the species' presence. On the base of gradients in ordination analysis, there were two main groups of species. In the first ''true'' forest bats group the tree-dwelling and gleaning species Myotis bechsteinii, Myotis nattereri and P. auritus dominated. Their occurrence was connected mainly with old forests of natural tree-species composition. The second group comprised species, which foraged in more open space or along the forest edge (with the farmland) and avoided closed interior (particularly Eptesicus serotinus, N. noctula, Nyctalus leisleri, Pipistrellus pipistrellus). The presence of mountain species Eptesicus nilssonii and Vespertilio murinus was associated mainly with dominance of spruce. Suggested predictive modelling of species composition in forest bat assemblages in conditions of natural forests can help in nature conservation.

In May -August, bats were mist-netted along an altitudinal gradient of 350-1350 m a.s.l. in the Poľana Mts area, to verify the correlation of species number decrease and the increase in elevation, to find which species could be predictors of certain altitude levels and to compare the sexual occurrence of species in various altitudes. Seventeen bat species were recorded. The most abundant mist-netted species were Myotis daubentonii (16%), M. myotis (13%) and M. mystacinus (12%). Otherwise, the most frequently caught species were M. mystacinus (40%), Eptesicus serotinus, M. myotis (26%) and Nyctalus leisleri (23%). In this study at a local scale, from oak to spruce vegetation stages, decreasing number of species with increasing altitude was found. Species dominance of the individual altitudinal levels was significantly different (15 species up to 600 m a.s.l., six species over 1100 m a.s.l.). The results indicated that the occurrence of some bat species, due to their ecological adaptations, is more or less characteristic for higher or lower altitudes of the Western Carpathians. The "lowland" species were considered to be mainly E. serotinus, Pipistrellus pipistrellus, N. noctula, N. leisleri and M. daubentonii. In higher elevations (more than 850 m), the presence of reproductive females was not found, of all but one, N. noctula, of the "lowland" species which are breeding in the area. The "mountain" species were considered to be E. nilssonii and Plecotus auritus. The general occurrence and reproduction of M. mystacinus and Barbastella barbastellus, was not limited by elevation.