Piotr Tryjanowski

Attributing physical and biological impacts to anthropogenic climate change

Significant changes in physical and biological systems are occurring on all continents and in most oceans, with a concentration of available data in Europe and North America. Most of these changes are in the direction expected with warming temperature. Here we show that these changes in natural systems since at least 1970 are occurring in regions of observed temperature increases, and that these temperature increases at continental scales cannot be explained by natural climate variations alone. Given the conclusions from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report that most of the observed increase in global average temperatures since the mid-twentieth century is very likely to be due to the observed increase in anthropogenic greenhouse gas concentrations, and furthermore that it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica, we conclude that anthropogenic climate change is having a significant impact on physical and biological systems globally and in some continents.

The design of artificial nestboxes for the study of secondary hole-nesting birds: a review of methodological inconsistencies and potential biases

Abstract. The widespread use of artificial nestboxes has led to significant advances in our knowledge of the ecology, behaviour and physiology of cavity nesting birds, especially small passerines. Nestboxes have made it easier to perform routine monitoring and experimental manipulation of eggs or nestlings, and also repeatedly to capture, identify and manipulate the parents. However, when comparing results across study sites the use of nestboxes may also introduce a potentially significant confounding variable in the form of differences in nestbox design amongst studies, such as their physical dimensions, placement height, and the way in which they are constructed and maintained. However, the use of nestboxes may also introduce an unconsidered and potentially significant confounding variable due to differences in nestbox design amongst studies, such as their physical dimensions, placement height, and the way in which they are constructed and maintained. Here we review to what extent the characteristics of artificial nestboxes (e.g. size, shape, construction material, colour) are documented in the ‘methods’ sections of publications involving hole-nesting passerine birds using natural or excavated cavities or artificial nestboxes for reproduction and roosting. Despite explicit previous recommendations that authors describe in detail the characteristics of the nestboxes used, we found that the description of nestbox characteristics in most recent publications remains poor and insufficient. We therefore list the types of descriptive data that should be included in the methods sections of relevant manuscripts and justify this by discussing how variation in nestbox characteristics can affect or confound conclusions from nestbox studies. We also propose several recommendations to improve the reliability and usefulness of research based on long-term studies of any secondary hole-nesting species using artificial nestboxes for breeding or roosting.

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.

Generation time and temporal scaling of bird population dynamics.

Theoretical studies have shown that variation in density regulation strongly influences population dynamics, yet our understanding of factors influencing the strength of density dependence in natural populations still is limited. Consequently, few general hypotheses have been advanced to explain the large differences between species in the magnitude of population fluctuations. One reason for this is that the detection of density regulation in population time series is complicated by time lags induced by the life history of species that make it difficult to separate the relative contributions of intrinsic and extrinsic factors to the population dynamics. Here we use population time series for 23 bird species to estimate parameters of a stochastic density-dependent age-structured model. We show that both the strength of total density dependence in the life history and the magnitude of environmental stochasticity, including transient fluctuations in age structure, increase with generation time. These results indicate that the relationships between demographic and life-history traits in birds translate into distinct population dynamical patterns that are apparent only on a scale of generations.

What affects the magnitude of change in first arrival dates of migrant birds

We analysed which among four factors (mean first arrival date, migration distance, changes in population size, detectability of species) influenced the magnitude of change (regression coefficient) in the first arrival dates of 30 migrant bird species in western Poland during 1983–2003. An examination suggested that several of these factors could be important: the regression coefficient was positively related to mean first arrival date (early species advancing their arrival date more) and negatively with change in population size (species in decline changing less). Moreover, significant differences in regression coefficient were detected between short and long distance migrants and between low detectable and highly detectable species. Undertaking a principal components analysis on the four factors produced an axis explaining 59% of the variance and whose positive values were associated with late arriving, long distance and low detectable species which were more likely to be in decline. However, the multi-collinearity of these factors is a problem that cannot be resolved here and we recommend that further work from different areas is needed to tease apart these effects.

Do White Storks Ciconia ciconia always profit from an early return to their breeding grounds

Capsule Arrival date strongly influenced date of breeding and breeding success. Aim To check our hypothesis that in years with low April temperatures, i.e. when storks started to breed, the relationship between timing of breeding and success would be absent, meaning that migrants would have no advantage by returning early to their breeding area. Methods We collected data in Poznań province, western Poland during the period 1983–2002. Based on local climatological data we selected eight cold spring years and compared them with the 12 ‘normal’ years. We analysed how weather affected the timing and arrival pattern of White Stork. Results The two groups of years did not differ significantly in population size, but in normal years the arrival date of both parents was earlier. Arrival date strongly influenced (was positively correlated with) date of breeding and (negatively correlated with) breeding success. Conclusion The slopes describing the above relationships did not differ significantly between the two groups of years. Therefore, we speculate that natural selection strongly favours birds that return early from the wintering grounds.

The geography of fear: a latitudinal gradient in anti-predator escape distances of birds across Europe

All animals flee from potential predators, and the distance at which this happens is optimized so the benefits from staying are balanced against the costs of flight. Because predator diversity and abundance decreases with increasing latitude, and differs between rural and urban areas, we should expect escape distance when a predator approached the individual to decrease with latitude and depend on urbanization. We measured the distance at which individual birds fled (flight initiation distance, FID, which represents a reliable and previously validated surrogate measure of response to predation risk) following a standardized protocol in nine pairs of rural and urban sites along a ca. 3000 km gradient from Southern Spain to Northern Finland during the breeding seasons 2009–2010. Raptor abundance was estimated by means of standard point counts at the same sites where FID information was recorded. Data on body mass and phylogenetic relationships among bird species sampled were extracted from the literature. An analysis of 12,495 flight distances of 714 populations of 159 species showed that mean FID decreased with increasing latitude after accounting for body size and phylogenetic effects. This decrease was paralleled by a similar cline in an index of the abundance of raptors. Urban populations had consistently shorter FIDs, supporting previous findings. The difference between rural and urban habitats decreased with increasing latitude, also paralleling raptor abundance trends. Overall, the latitudinal gradient in bird fear was explained by raptor abundance gradients, with additional small effects of latitude and intermediate effects of habitat. This study provides the first empirical documentation of a latitudinal trend in anti-predator behavior, which correlated positively with a similar trend in the abundance of predators.

Selectivity of harvesting differs between local and foreign roe deer hunters : trophy stalkers have the first shot at the right place

Harvesting represents a major source of mortality in many deer populations. The extent to which harvesting is selective for specific traits is important in order to understand contemporary evolutionary processes. In addition, since such data are frequently used in life-history studies, it is important to know the pattern of selectivity as a source of bias. Recently, it was demonstrated that different hunting methods were selected for different weights in red deer (Cervus elaphus), but little insight was offered into why this occurs. In this study, we show that foreign trophy stalkers select for larger antlers when hunting roe deer (Capreolus capreolus) than local hunters, but that close to half of the difference in selectivity was due to foreigners hunting earlier in the season and in locations with larger males. The relationship between antler size and age was nevertheless fairly similar based on whether deer was shot by foreign or local hunters.

Effect of Water Level and Livestock on the Productivity and Numbers of Breeding White Storks

Abstract We studied numbers and productivity of the European White Stork (Ciconia ciconia) during 1968-2002 at Kłopot village colony (in the Odra River valley, Poland) and their response to water level and livestock farming. The number of nesting pairs (range 19-33) fluctuated independently of the April and June water level, but correlated with the presence of a local livestock farm. The average number of chicks fledged per pair was negatively correlated with the water level in April, when White Storks choose the breeding area. The White Stork appears to use farming activity rather than water level in making a decision as to where to a settle. This result suggests that changes in management practices, which are relatively easily made, may improve demographic parameters of local breeding White Storks.

Sex differences in nest defence by the red-backed shrike Lanius collurio: effects of offspring age, brood size, and stage of breeding season

The red-backed shrike Lanius collurio is an open-cup nesting passerine bird, which protects its nest aggressively attacking predators near the nest. The response of parents to a human observer was investigated during the nesting period 1999–2001 in Poland. The intensity of nest defence increased as the breeding cycle progressed in accordance to the offspring value hypothesis. However, we did not find an increase in the level of aggression according to the number of offspring and the time of season. Contrary to previous predictions, we did not find gender differences in nest defence. More aggressive parents, both females and males, have significantly better breeding success than quieter individuals.