Marcin Tobolka

Conservation of farmland birds faces different challenges in Western and Central-Eastern Europe

Abstract. Birds are commonly used as an example of the strongly declining farmland biodiversity in Europe. The populations of many species have been shown to suffer from intensification of management, reduction of landscape heterogeneity, and habitat loss and fragmentation. These conditions particularly dominate farmland in the economically well developed countries of Western Europe. Currently, the farmland environment in Central-Eastern Europe is generally more extensive than in Western Europe and a larger proportion of people still live in rural areas; thus generating different conditions for birds living in agricultural areas. Furthermore, the quasi-subsistence farming in much of Central-Eastern Europe has resulted in agricultural landscapes that are generally more complex than those in Western Europe. To protect declining bird populations living in farmland, detailed knowledge on both species and communities is necessary. However, due to scientific tradition and availability of funding, the majority of studies have been carried out in Western Europe. In consequence this provokes a question: are findings obtained in western conditions useful to identify the fate of farmland bird biodiversity in Central-Eastern Europe? Therefore, the major goal of this paper is to highlight some local and regional differences in biodiversity patterns within EU farmland by comparing intensive agricultural landscapes with more extensive ones. More specifically, we aim to outline differences in agricultural landscapes and land use history in the two regions, use farmland birds to provide examples of the differences in species dynamics and species-habitat interactions between the two regions, and discuss possible social and ecological drivers of the differences in the context of biodiversity conservation. Factors governing spatio-temporal dynamics of farmland bird populations may differ in intensive and extensive landscapes as illustrated here using the Grey Partridge Perdix perdix and the Red-backed Shrike Lanius collurio as examples. The unevenness of farmland bird studies distribution across Europe was also presented. We call for more emphasis on pluralism in furthering both pan-European research on farmland bird ecology and conservation strategies. We also highlight some features specific to Central-Eastern Europe that merit consideration for the more efficient conservation of farmland birds and farmland biodiversity across Europe.

Effects of management intensity and orchard features on bird communities in winter

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.

Landscape structure, human disturbance and crop management affect foraging ground selection by migrating geese

AbstractIt is well known that agricultural intensification has caused severe population declines among bird species which use farmland for breeding and overwintering, while migrating bird species may benefit from intensive farming, but in turn damage crops. Knowledge of the habitat selection of migrating birds is important from both a conservation and agro-economic point of view. We investigated the habitat preferences of three common migrating goose species: White-fronted Goose Anser albifrons, Bean Goose A. fabalis and Greylag Goose A. anser during the autumn of 2009 in western Poland. A total of 24 flocks of these species were identified. Geese preferred large, elevated fields that were remote from forests and human settlements but in close proximity to a lake. Geese selected maize stubbles and avoided winter cereals. They selected sites in landscapes with a lower diversity of crops. Flock size was negatively correlated with the proportion of pastures in the landscape, but it increased with field size, distance to forest and distance to town. Our results are in contrast with the paradigm that less intensive farmland positively influences habitat use by birds during foraging. We advise the delayed ploughing of stubbles with the aim of creating appropriate foraging habitats for geese and minimizing damage to cereal crops.ZusammenfassungLandschaftsstruktur, menschliche Störung und Anbaumethoden beeinflussen die Nahrungsflächenwahl wandernder Gänse Die Intensivierung der Agrarwirtschaft hat starke Populationsrückgänge sowohl brütender als auch überwinternder Vogelarten in landwirtschaftlich genutzten Flächen verursacht. Dennoch können ziehende Vogelarten von der intensiven Landwirtschaft profitieren, aber auch Kulturpflanzen schädigen. Sowohl aus Sicht des Naturschutzes, als auch aus agrarökonomischer Sicht ist es wichtig, Kenntnisse über die Habitatwahl der Gänse zu erlangen. Vor diesem Hintergrund untersuchten wir im Herbst 2009 in Westpolen die Habitatpräferenzen dreier häufiger und ziehender Gänsearten: Blässgans Anser albifrons, Saatgans Anser fabalis und Graugans Anser anser. Insgesamt fanden wir 24 Trupps dieser Arten. Die Gänse bevorzugten große, erhöhte Felder, die in der Umgebung eines Sees und abseits von Wäldern und menschlichen Siedlungen lagen. Die Gänse wählten Maisstoppeln und mieden Wintergetreide. Sie selektierten Gebiete in Landschaften mit einer geringen Diversität an Anbaupflanzen. Die Truppgröße war negativ korreliert mit dem Grünlandanteil der Landschaft. Truppgrößen erhöhten sich mit der Feldgröße und mit den Distanzen zu Wäldern und Siedlungen. Unsere Ergebnisse stehen im Gegensatz zum Paradigma, dass weniger intensive Landnutzung die Habitatnutzung der Vögel während der Nahrungssuche positiv beeinflusst. Wir empfehlen ein verspätetes Pflügen der Stoppeln, um geeignete Nahrungshabitate für Gänse zu schaffen und damit die Schädigung von Getreidepflanzen zu minimieren.

The effect of extreme weather events on breeding parameters of the White Stork Ciconia ciconia

Capsule Although the White Stork avoids adverse weather conditions by modifying its arrival and breeding, it cannot avoid extreme weather events during the breeding season. Aims To show how extreme weather conditions can influence breeding attempts of a large, long-lived species, the White Stork. Methods We analysed data on arrivals of White Storks in Western Poland from 2005 to 2013 and detailed breeding biology parameters from 2009 to 2013 in relation to weather conditions. We analysed breeding success and breeding failure rate from 1974 to 2013. Results In years with a cold March White Storks arrived later than when March was warmer. Frost during incubation negatively influenced the hatching success. Extreme weather events caused high late mortality even for nestlings older than 30 days. Data from 27 breeding seasons showed a significant increase in mean breeding success but also a significant increase in the proportion of pairs which lost broods in the nestling stage. Conclusion The White Stork can modify its arrival in response to current weather conditions on the breeding grounds but it cannot respond to extreme weather events. Due to increasing frequency of extreme weather events caused by climate change, White Stork breeding success may decrease in the future.

New is not always better: low breeding success and different occupancy patterns in newly built nests of a long-lived species, the white stork Ciconia ciconia

Capsule An increase in new nest building in a white stork population revealed that they were built further from human settlement and on non-typical structures; such nests had lower breeding success resulting from later breeding. Aim To determine why some birds build new nests rather than occupy older ones, and how new nests affect breeding performance compared to old nests, in a long-lived bird, the white stork. Methods We compared new nest construction in 2010 with a long-term data set on white stork in Western Poland from 1974 to 2009. For data from 2010, we analysed nest location and breeding biology in detail. Results Since 1974, the proportion of new build nests was ca. 1.6%; in 2010 this was 13.2%. Pairs in new nests bred later than pairs in old, and had smaller clutches and lower breeding success. New nests were located further from settlements and tended to be built on different structures. A significantly lower proportion of new nests were re-occupied in subsequent years. Conclusions Pairs may build new nests to gain experience in nest building, cooperation and foraging for subsequent seasons or because of competitive pressure when the environment is close to carrying capacity. Breeding success can be initially very low.

Cranial lesions caused by helminth parasites and morphological traits in the European polecat Mustela putorius

SummaryWe investigated the occurrence of cranial lesions caused by helminth parasites in the European polecat Mustela putorius in a museum collection in Slovakia. Selected traits of polecat body morphology and condition were studied with respect to the prevalence of the parasites, and number and extent of helminth-caused lesions in crania of 183 adult polecats. The trematode Troglotrema acutum was identified as the parasitic agent (prevalence 62.6 %), with a strong relationship between number of lesions and extent of cranial damage (surface of cranium). Prevalence of infection did not differ significantly between sexes (68.9 % in females, 51.1 % in males). Females with lesions by Troglotrema acutum have significantly greater braincase breadth than uninfected ones. Among males, infected individuals were generally significantly heavier and larger than uninfected individuals. Therefore, contrary to assumptions, it seems that parasites did not influence significantly body measurements of the animals, and differences are probably rather a result of an intra-sample age variation among infected polecats (older individuals are bigger, more probably infected and damage is more pronounced).

Constant and seasonal drivers of bird communities in a wind farm: implications for conservation

Background. One of the most difficult challenges for conservation biology is to reconcile growing human demands for resources with the rising need for protecting nature. Wind farms producing renewable energy have been recognised to be a threat for birds, but clear directives for environmental planning are still missing. Methods. Point counts were performed to study the relationship between eight environmental variables and bird populations in different parts of a year on the largest Polish wind farm between March 2011 and February 2013. Variables potentially related to species richness (Chao 1 estimator) and the abundance of the entire bird community as well as five selected farmland species were analysed with the use of generalized linear mixed models. Results. Some associations between the studied variables and bird populations were season/year specific, while others had a constant direction (positive or negative) across seasons and/or years. The latter were distance to the nearest turbine, field size, number of wind turbines, proximity of settlements and water bodies. Spatial autocorrelation and counting time were significantly correlated with bird population estimates but the directions of these relationships varied among seasons and years. Associations between abundance of individual species and environmental variables were species-specific. Conclusions. The results demonstrated a constant negative relationship between wind turbine proximity and bird numbers. Other environmental variables, such as field size, proximity of settlements and water bodies that also had constant associations with bird populations across seasons may be taken into account when minimizing adverse effects of wind farm development on birds or choosing optimal locations of new turbines.

Seasonal changes in avian communities living in an extensively used farmland of Western Poland

Abstract To study the seasonal changes in avian communities, we collected data in an extensively used farmland in Western Poland during 2006-2013. Generalized additive mixed models were used in order to study the effects of seasonality and protected areas on the overall bird species richness. A similarity percentage analysis was also conducted in order to identify the species that contribute most strongly to dissimilarity among each bird according to the phenological season. Furthermore, the differences in bird communities were investigated applying the decomposition of the species richness in season, trend, and remainder components. Each season showed significant differences in bird species richness (seasonality effect). The effect of the protected areas was slightly positive on the overall species richness for all seasons. However, an overall negative trend was detected for the entire period of eight years. The bird community composition was different among seasons, showing differences in terms of dominant species. Greater differences were found between breeding and wintering seasons, in particular, the spatial pattern of sites with higher bird richness (hotspots) were different between breeding and wintering seasons. Our findings showed a negative trend in bird species richness verified in the Polish farmlands from 2006. This result mirrors the same negative trend already highlighted for Western Europe. The role of protected areas, even if slightly positive, was not enough to mitigate this decline process. Therefore, to effectively protect farmland birds, it is necessary to also consider inter-seasons variation, and for this, we suggest the use of medium-term temporal studies on bird communities’ trends.

Habitat selection taking nest-box age into account: a field experiment in secondary hole-nesting birds

Abstract. The widespread use of nest-boxes significantly improved our understanding of the ecology and behaviour of secondary cavity-nesting birds. Although former investigations showed that nest-box characteristics (e.g. physical dimensions, material) may determine where birds will roost or breed, biological consequences of the age of nest-boxes have been rarely investigated with field experiments. To test if age of cavities may influence roosting or breeding behaviour in cavity-nesting birds, we created a set-up of three experimental groups of wooden boxes with the same physical dimensions: old boxes that were occupied at least once for nesting during years prior to this study, old boxes that were never accepted for breeding during years prior to this study, and new boxes. Half of the old boxes were relocated within the study plot and replaced by new ones. Box age did not have an impact on occupation rates during the winter period, and therefore did not seem to influence where the birds roosted. However, breeders occupied the old previously unoccupied boxes less frequently than the other boxes. Moreover, birds bred much earlier in new boxes than in the old boxes that were previously never exploited. We discuss when and how cavity age can influence roosting or breeding in nest-box exploiters. Our results strongly suggest that maintenance procedures of plots where old boxes are replaced by new ones can influence how and where birds will breed.

Factors determining presence of passerines breeding within White Stork Ciconia ciconia nests

Nests of White Stork Ciconia ciconia are commonly used by various passerines as nesting sites. In this study, we investigated factors determining presence and number of pairs of species breeding within White Stork nests in an extensive farmland in NE Poland. In 133 (57%) out of 233 White Stork nests, we found at least one breeding pair of passerine bird. These were from three species: House Sparrows Passer domesticus (68% of 133 nests with co-breeding), Tree Sparrows Passer montanus (65%), and Starlings Sturnus vulgaris (30%). The probability of breeding passerines within White Stork nests increased with increasing nest thickness, and was significantly higher in currently occupied nests. Sparrows were more likely to breed in White Stork nests located on electricity poles, situated closer to settlements and surrounded mainly by arable fields where meadows were not prevalent. In this paper, we show that White Stork nests are favorable nesting sites for passerines, as they are well insulated and provide an anti-predatory shield.