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Capsule: Different methods of comparing bill morphology between woodpecker species show different, but not contradictory results.Aims: Differences among similar, closely related species which co-oc...

Urbanization poses threats and opportunities for the biodiversity of wild bees. At the same time, cities can harbor diverse wild bee assemblages, partly due to the unique plant assemblages that provide resources. While bee dietary preferences have been investigated in various studies, bee dietary studies have been conducted mostly in nonurban ecosystems and data based on plant visitation observations or palynological techniques. This data set describes the larval food preferences of four wild bee species (i.e., $Chelostoma florisomne, Hylaeus communis, Osmia bicornis$ and $O. cornuta$)common in urban areas in five different European cities (i.e., Antwerp, Belgium; Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). In addition, the data set describes the larval food preferences of individuals from three wild bee genera (i.e., $Chelostoma $sp., $Hylaeus$ sp., and $Osmia $ sp.) that could not be identified to the species level. These data were obtained from a Europe-level study aimed at understanding the effects of urbanization on biodiversity across different cities and cityscapes and a Swiss project aimed at understanding the effects of urban ecosystems in wild bee feeding behavior. Wild bees were sampled using standardized trap nests at 80 sites (32 in Zurich and 12 in each of the remaining cities), selected following a double gradient of available habitat at local and landscape scales. Larval pollen was obtained from the bee nests and identified using DNA metabarcoding. The data provide the plant composition at the species or genus level preferred by each bee. These unique data can be used for a wide array of research questions, including urban ecology (e.g., diversity of food sources along urban gradients), bee ecology (characterization of bee feeding preferences), or comparative studies on the urban evolution of behavioral traits between urban and nonurban sites. In addition, the data can be used to inform urban planning and conservation strategies, particularly concerning flower resources (e.g., importance of exotic species and, thus, management activities). This data set can be freely used for noncommercial purposes, and this data paper should be cited if the data is used; we request that collaboration with the data set contact person to be considered if this data set represents an important part of the data analyzed in a study., Ecology, 103 (9), ISSN:0012-9658, ISSN:1939-9170

Specialized conifers-seed-eating animals, such as crossbills (Loxia spp.), woodpeckers (Picidae), squirrels (Sciuridae), nutcrackers (Nucifraga spp.) and many of insects (e.g., Pyralidae and Tortricidae) exert phenotypic selection on different features of the coniferous cones. In response to such selection, many conifers invest resources in various physical and chemical seed defenses. The study was conducted in mixed mountain forests in West Sudetes (50°55’N 15°46′E), southwest Poland. We selected 10 anvils for great spotted woodpecker and 12 foraging places for the red squirrel. We collected 350 foraged larch cones from each anvil and feeding place for both species and also 50–100 unforaged larch cones within a 15 m radius at each site. In this study, we documented different selection pressures on European larch (Larix decidua) cones exerted by great spotted woodpecker (Dendrocopos major) and red squirrels (Sciurus vulgaris). The great spotted woodpecker preferred foraging on cones with thinner peduncles resulting in selection for thicker peduncles. However, red squirrels preferred feeding on small and medium larch cones, favoring trees producing large cones. Different foraging behaviors influence the form of selection exerted by these two seed-eating species.

Background Intentional winter bird feeding in gardens is one of the most common interactions between birds and humans. Because feeding may have both desired effects (provisioning of nutritious food for under-nourished birds) and undesired effects (favouritism of competitively superior species, transmission of disease), management of supplementary sites should be optimized from an ecological and conservation perspective. Therefore, the main aim of this study was to experimentally test winter food preferences of birds, with underlying potential influence of habitat (rural vs. urban) on realised food preferences pattern. Methods We conducted an experimental analysis of food preferences of wintering birds by provided bird-feeders in urban and rural environments across Poland. Data were collected twice during winter 2013–2014 across Poland, in total with 80 experimental trials. Results Sunflower seeds were the most preferred food supplement both in urban and rural habitats, significantly more exploited than any other food simultaneously available in feeders (animal fat, millet seed and dry fruits of rowanberry). However, no significant differences were recorded between urban and rural habitats in use of food. Conclusions The degree of use of a particular type of food at bird-feeders depended on the overall use of food in a bird-feeder—consumption of each of the four types of food was significantly positively correlated with that of the others, and it was positively correlated with the number of birds observed at the feeders.

In their first phase of expanding into new areas, invasive plants often take advantage of the inability of existing herbivores and pathogenic species to exploit them. However, in the longer term local enemies may adapt to using these invasive species as a food source. This study assesses the use of mature acorns of two oak species in Europe (the native Pedunculate Oak Quercus robur and the invasive Northern Red Oak Quercus rubra) by moths Cydia fagiglandana and Cydia splendana and beetles Curculio spp. We show that acorns of invasive oak species can be equally attractive to C. splendana but only partially so to C. fagiglandana where infestation rates where significantly lower (approximately half) compared to the native oak. The infestation by Curculio beetles of Northern Red Oak was marginal, less than 1% of the rate in the native oak species. The larval final weights did not differ significantly between host species, but emergence of C. splendana and Curculio spp. took significantly longer in acorns of Northern Red Oak. It is likely that C. fagiglandana and C. splendana have increased their niche breadths by exploiting invasive oak species and avoiding competition with the Curculio weevils. Furthermore, the occurrence of Northern Red Oak could stabilize food resources during years when native oak species have poor acorn crops.

The red squirrel (Sciurus vulgaris) is an arboreal species, relatively common in mixed, deciduous and coniferous forests and in urban parks. From autumn to early spring the main diet of red squirrels is seeds in closed conifer cones. In this study, we investigated characteristics of a habitat in western Poland where red squirrels were feeding on Scots pine (Pinus sylvestris). Understory cover, number of tree species, distance to an open area, distance to the nearest great spotted woodpecker (Dendrocopos major) anvil, and size of ten randomly selected Scots pine trees were measured on 70 transects. We used binary logistic regression to test which forest habitat parameters affected the presence of feeding signs of red squirrels. Feeding signs of red squirrels were found from sites close to forest edges with less understory cover, higher tree-species richness and larger size of trees. Red squirrels did not avoid sites close to great spotted woodpecker anvils. We conclude that forest stand structure is import...

Relatively few animal species extract seeds from closed conifer cones because of the forces required to spread apart or penetrate the woody scales. Those species that forage on seeds in closed cones tend to forage selectively, and therefore act as selective agents on cone structure. However, little is known about the foraging preferences and thus phenotypic selection that is exerted on conifers by many species that forage extensively on seeds in closed cones, including especially woodpeckers (Picidae). Great spotted woodpeckers Dendrocopos major are one of the main predators of seeds in closed cones of Scots pine Pinus sylvestris in central and eastern Europe. To estimate the cone preferences of these woodpeckers foraging on Scots pine, we contrasted traits of cones that were and were not foraged on by woodpeckers. Woodpeckers preferred to forage on shorter cones when scales were thin (smaller apophyses) but preferred cones of intermediate length when scales were thicker, providing evidence for correlational selection. The preference for intermediate-sized cones indicates that woodpeckers exert disruptive selection on cone length when cones have thicker scales, but the overall selection on cone length across all scale types indicates directional favoring the evolution of longer cones. Woodpeckers avoided cones with thicker scales, which would lead to directional selection favoring the evolution of thicker scales. Preferences for intermediate-sized cones have been found in tree squirrels and directional selection favoring the evolution of cones with thicker scales may be a common outcome of the foraging behavior of birds.

Natural hybridisation between the taxa from Pinus mugo complex and P. sylvestris was postulated in several sympatric populations of the species in Europe. However, due to the absence of precise methods for identification of hybrid seeds and hybrid trees, the frequency of hybridisation and its influence on the genetic structure of relict P. mugo populations has not been clarified so far. In the present study, the species-specific chloroplast DNA (cpDNA) marker and isozymes were applied to test the hybridisation hypothesis in a postulated hybrid swarm population of the species from “Bor na Czerwonem” reserve at the northern foothills of Tatra Mts., Poland. The cpDNA marker was used to identify hybrids within two groups of polycormic (multi-stemmed) and monocormic (single-stemmed) pines from this population. Allelic frequencies at isozyme loci from both groups were compared to frequencies found in allopatric populations of the species. Additionally, cpDNA haplotypes of seedlings derived from open pollinated seeds were studied to detect the possibility of successful cross-pollination. The mixture of seedlings with P. sylvestris and P. mugo cpDNA haplotypes was derived from one parental tree that indicates hybridisation. However, all the mature polycormic pines had cpDNA haplotypes species specific to P. mugo and the isozyme frequencies were similar to frequencies found in three allopatric populations of P. mugo from Tatra Mts. (mean genetic distance, Dn=.027). The differences were much larger in comparisons with monocormic pines from this area (Dn=.085) and two P. sylvestris samples from distant allopatric populations (Dn=.077). Nearly all monocormic pines had cpDNA species specific to P. sylvestris and isozyme frequencies similar to other populations of this species (mean Dn=.004). Only one P. sylvestris-like monocormic tree had cpDNA of P. mugo and can be considered as a hybrid. The results do not provide evidence supporting the hybrid swarm hypothesis. Rather, the results suggest that mature hybrids have a low frequency within this population and (rare) hybridisation is not reciprocal but unidirectional with P. mugo as pollen donor.

Seeds are under strong pressure from seed predators. Therefore any physical seed trait increasing the chances of the seed's survival should undergo positive selection. Seed color polymorphism, varying from pale to dark seeds, occurs in Scots pine (Pinus sylvestris), a keystone species of coniferous forests in Eurasia. This phenomenon can be explained by the production of large quantities of empty, always pale colored, seeds, with the opportunity for mimicry of these worthless seeds to avoid predation. Here, we investigated how the color of empty seeds may influence the foraging choices of the most common visual seed predator in temperate forests, the Chaffinch (Fringilla coelebs). We show, from field experiments, that different colored seed had different probabilities of predation by the chaffinch, and that predation was highest for dark seeds and lowest for pale empty seeds. Thus, the occurrence of empty seeds might benefit full seeds which mimic their coloration, even for those which are highly visible on the ground. In conclusion, the study demonstrated that mimicry by seeds of the color of the ground did not improve their survival but the production of pale full seeds resembling empty seeds did. This contradicts previous results and indicates that color polymorphism may reduce the predation rate by birds.

The knowledge and conservation of diminishing valuable habitats in agricultural landscapes are of key importance in saving declining farmland biodiversity. One of these habitats is the traditional orchard whose role in supporting birds is still poorly known, especially in winter. We counted birds in 106 orchards differing in management intensity (abandoned, traditional, and intensive) during December 2009 and January 2010 in Wielkopolska, western Poland and measured site characteristics and composition of surrounding landscapes for every orchard. Old abandoned and traditionally managed orchards had significantly higher bird species richness than intensive ones. Irrespective of orchard type, bird species richness as well as density were positively influenced by the cover of unmown herb layer in orchards and tree diversity. Tree and fruit densities positively affected bird species richness and density mainly in abandoned orchards while in other orchard types the effect of these variables was less pronounced. Land cover diversity in a landscape had a positive effect on species richness and density mostly in abandoned orchards and we believe that this effect reflects the elevated utilization of such orchards by birds from the surrounding landscape. Thus, abandoned, as well as traditionally managed orchards seems to be especially important habitats that offer food source and refuge for wintering birds and should be protected. We propose to diversify fruit production by planting various tree species, leaving part of the herb layer unmown and several trees unharvested in intensive orchards in order to improve suitability of modern orchards for birds.