Vladimír Bejček

Changes in bird community composition in the Czech Republic from 1982 to 2004: increasing biotic homogenization, impacts of warming climate, but no trend in species richness

AbstractRecent major environmental changes could lead to homogenization in the composition of plant and animal communities, with generalist species replacing more specialized species, as well as to the increased domination of species adapted to warmer climatic conditions. Using common bird monitoring data, we have tested whether these patterns can be observed in the long-term changes in the structure and species richness of bird communities in the Czech Republic. We focused on a comparison of two time periods (1982–1990 and 1991–2004) that differ in land use (high agricultural intensity in the former, and a drop in agricultural intensity accompanied by forest expansion in the latter). We found that bird communities became less specialized and that this decline in specialization did not change after 1990. In contrast, taxonomic homogenization increased during the first time period but declined at the beginning of the second one. Moreover, the community composition developed towards a dominance of species breeding in warmer climates, and this change coincided with an increase in spring temperatures. Therefore, it would appear that both functional and taxonomic homogenization took place in the 1980s but the latter did not continue in subsequent decades. Species richness of local bird communities did not show any trend over time. We suggest that climate warming might be an important driving force of changes in the bird community composition in the Czech Republic, but the role of land-use changes is less clear, although it is probable that habitat specialists probably did not benefit from lower intensity of agricultural activities and increased forest cover.ZusammenfassungÄnderungen in der Zusammensetzung von Vogelgemeinschaften in der Tschechischen Republik zwischen 1982 und 2004: zunehmende biotische Vereinheitlichung, Einfluss von Klimaerwärmung, aber kein Trend im Artenreichtum Aktuelle große Veränderungen in der Umwelt könnten zu einer Vereinheitlichung der Zusammensetzung von Tier- und Pflanzengemeinschaften führen, wobei Generalisten die spezialisierteren Arten ersetzen und Arten dominieren, die an wärmere Klimate angepasst sind. Anhand normaler Vogel-Monitoring Daten testen wir in dieser Studie, ob sich diese Muster in langfristigen Veränderungen in der Struktur und dem Artenreichtum der Vogelgemeinschaften in der Tschechischen Republik beobachten lassen. Wir konzentrieren uns auf einen Vergleich zwischen zwei Zeiträumen (1982–1990 und 1991–2004), die sich in der Landnutzung unterscheiden (intensive Landwirtschaft im früheren und ein Absinken der Intensität der Landnutzung begleitet von einer Ausbreitung von Waldgebieten im letzteren). Wir fanden, dass die Vogelgemeinschaften weniger spezialisiert wurden, und diese Abnahme der Spezialisierung änderte sich nicht nach 1990. Dagegen stieg die taxonomische Vereinheitlichung während des ersten Zeitraums an, nahm aber am Beginn des zweiten wieder ab. Darüber hinaus entwickelte sich die Zusammensetzung der Gemeinschaft hin zu einer Dominanz von Arten, die ihre Brutgebiete in wärmeren Klimaten haben, und diese Änderung fiel zusammen mit einem Ansteigen der Frühlingstemperaturen. Daher scheint es, als hätten sowohl die funktionale als auch die taxonomische Vereinheitlichung in den 1980er Jahren stattgefunden, aber die erstere schritt später nicht fort. Der Artenreichtum lokaler Vogelgemeinschaften zeigte keinerlei Trend über die Zeit. Wir stellen zur Diskussion, dass die Klimaerwärmung eine treibende Kraft sein könnte für Änderungen in der Zusammenstellung der Vogelgemeinschaft in der Tschechischen Republik, jedoch ist die Rolle der Landnutzung weniger klar. Arten, die auf ein bestimmtes Habitat spezialisiert sind, konnten wahrscheinlich nicht profitieren von der weniger intensiven Landnutzung und der Zunahme der Wälder.

Changes in bird distribution in a Central European country between 1985–1989 and 2001–2003

European birds have been significantly affected by dramatic environmental changes during the last decades. The effects of these changes on species richness and distribution in particular countries are still poorly understood because of a lack of high-quality, large-scale data standardized over time. This is especially true in Central and Eastern Europe. On a model group of birds in the Czech Republic (countrywide atlas mapping data), we examined whether long-term changes of species richness and distribution between 1985–1989 and 2001–2003 differed among groups of species defined by their habitat requirements, type of distribution in Europe, migratory strategy and the degree of national legal protection. Further, we investigated the effects of colonizers and local extinctions on these changes. Whereas the number of species in the whole country remained the same in both periods (208 species), species composition had changed. Increasing occupancy (i.e., number of occupied mapping squares) was observed in species of forest and wetland habitats, in short-distance migrants and in non-protected species. Southern species also positively changed their occupancy, but this pattern disappeared after the inclusion of six species dependent on extensively cultivated farmland that went extinct between mappings. The overall occupancy of all species together showed positive changes after excluding colonizers and extinct species. We suggest that the improvement of environmental conditions after 1990 caused the stability of or increased the distribution of common birds in the Czech Republic, and it was the disappearance of specific farmland practices that might have caused the loss of several species.

Population increase of forest birds in the Czech Republic between 1982 and 2003

Capsule Populations of most forest bird species increased between 1982 and 2003, probably due to increased forest cover and changes in forest age-class composition. Aims To determine population changes of forest birds in the Czech Republic and to determine their possible causes. Methods Population data were collected via the Breeding Bird Monitoring Programme, which is based on skilled volunteers counting birds at point transects using a standardized technique. Population trends and indices for the period 1982–2003 were calculated for 47 species using log-linear models. Published data on development of forest cover and forest age composition in the Czech Republic were used to indicate environmental change over the same period. Results Populations of most forest species increased between 1982 and 2003. There was also an increase in forest cover and an increase in the proportion of older forest age-classes. The increase in forest specialist birds was positively correlated with the average increase in forest coverage. Conclusions The populations of Czech forest birds have increased in the last two decades. This contrasts with widely reported declines of farmland bird populations throughout Europe. The correlation between populations of specialized forest species and extent of forest habitat suggests that changes in land-use are an important factor. However, increasing cover of mature forests could have a similar effect on the populations of specialist species.

Contrasting Effects of Climatic and Habitat Changes on Birds with Northern Range Limits in Central Europe as Revealed by an Analysis of Breeding Bird Distribution in the Czech Republic

Abstract. The results of spatial modelling based on various climatic change scenarios predict shifts in the geographical ranges of species. Theoretically, a species can spread into new areas if the local habitat composition meets its ecological requirements. Therefore, habitat change in an unfavourable direction should inhibit climatically induced range shifts in some species. We tested this prediction using data on breeding bird distribution in the Czech Republic, a small central European country. We selected 28 species whose northern range limits are in central Europe and compared their distribution in the Czech Republic between 1985–1989 and 2001–2003. From these species, we identified 10 affected by habitat changes, such as a loss in environmental heterogeneity or agricultural intensification, using a local literature survey. As a group, the 28 species did not show any significant changes in their breeding distribution. However, those species affected by habitat change significantly restricted their distribution, whereas the remaining species not affected by habitat change increased their distribution. We suggest that the increasing occupancy of species not affected by habitat change could be caused by climate change. However, climate cannot overshadow the negative impacts of land-use changes on the distribution of species affected by habitat change. Therefore, such species could be seriously threatened: they might not be able to track their climatic optima if future climate change proceeds in tandem with the destruction of their habitats.

Influence of parasitism on the use of small terrestrial rodents in environmental pollution monitoring.

Bioaccumulation of cadmium, chromium, copper, manganese, nickel, lead and zinc in small terrestrial rodents - voles and their cestode parasite Paranoplocephala dentata was studied. Contents of Pb, Mn, Ni and Zn in the parasite were found to be higher than in the kidney and liver of the parasitized animals. Lead level in the cestode was 37 fold higher than in the liver of the infected rodents. Bioaccumulation factors of zinc, nickel and manganese in the cestode are mostly in the range from 2 to 4.5. Considering the different contents of manganese and zinc in livers of non-parasitized and parasitized rodents, kidney tissue was found to be more reliable than liver as an indicator of environmental pollution by manganese and zinc; the kidneys of parasitized animals showed no significant change in the concentrations of those elements that are accumulated in the cestode.

Mitochondrial DNA sequence variation and evolution of Old World house mice (Mus musculus)

Abstract. We analyzed sequences of two variable segments of the mitochondrial control region (CR) and flanking regions in the house mouse (Mus musculus). Most of the material was sampled from the eastern Mediterranean and the Middle East, i.e., a source area for the colonization of Europe. These sequences were supplemented with other samples from the whole range of the species including the Yemeni island of Socotra. This island was shown to harbour mice bearing M. m. domesticus and M. m. castaneus CR haplotypes. In addition, we found 10 distinct sequences at the same locality that were markedly different from all known CR sequences. Sequencing of the whole mitochondrial genome suggested these sequences to represent nuclear fragments of the mitochondrial origin (numts). We assessed genetic variation and phylogeography within and among the house mouse subspecies and estimated the substitution rate, coalescence times, and times of population expansion. We show the data to be consistent with time dependency of substitution rates and recent expansion of mouse populations. The expansion of European populations of M. m. musculus and M. m. domesticus estimated from the CR sequences coincide with presumed time of colonization of the continent in the Holocene.

Relationships between winter temperature and breeding bird abundance on community level: importance of interspecific differences in diet

Abstract. Winter weather limits populations of resident bird species. Although many small-scale or speciesspecific studies illustrated this fact, our knowledge of interspecific differences in population responses to winter temperatures is incomplete due to lack of community-level studies. For this purpose, we have used long-term monitoring data on breeding bird populations of 37 common bird species wintering in the Czech Republic. We predicted that species will differ in their relationship between winter temperature and abundance with respect to their body mass and dietary niche. Smaller species having relatively higher energy expenditure should show closer relationship between breeding abundance and winter temperature than larger species. Concerning dietary niche, abundance of species feeding on animals should be more affected by temperature than abundance of species feeding on plants or omnivorous species. Our results confirmed the second prediction: populations of species preying on animals followed winter temperatures more closely than populations of species feeding on both animals and plants. Food-mediated mortality is probably more important than direct effects of low temperatures. In general, relationships between abundance and temperature were relatively weak in most species and we suggest that possible changes in winter temperatures may not seriously affect populations of common breeding birds in the Czech Republic.

Numbers of wintering waterbirds in the Czech Republic: long-term and spatial-scale approaches to assess population size

Capsule Two nationwide monitoring schemes, the International Waterbird Census (IWC) and Atlas of Wintering Birds (AWB), provide comparable estimates of national population sizes of wintering waterbirds. Differences between these estimates for several species can be explained by differences in their migratory strategy. Aims We tested whether species-specific variables, i.e. the total numbers, distribution and migration strategy affected the accuracy of wintering population estimates provided by two different monitoring schemes, the IWC and AWB. Methods Estimates of the numbers of 81 waterbird species are compared, using data from IWC (mid-January) and AWB (December, January and February) in the Czech Republic between 1982 and 1985. Log-linear Poisson regression analysis was used to estimate missing IWC data from long-term IWC data series (1966–2013) using Trends and Indices for Monitoring data software. A series of generalized linear models was estimated to analyse the effect of species-specific variables on the presence of overlap between IWC and AWB national population estimates. Results The range of numbers recorded by IWC data overlap the range of AWB numbers in 22 of the 53 investigated species recorded by both monitoring schemes. Numbers of most other species based on the IWC counts were lower when compared with those generated from AWB data and included several widespread species, e.g. White-tailed Eagle Haliaeetus albicilla and White-throated Dipper Cinclus cinclus. In contrast, population size estimates based on IWC counts were higher than those generated from AWB estimates for one species, the Ferruginous Duck Aythya nyroca. The differences between IWC and AWB estimates were significantly higher in late-departing and early-arriving migrants. There was no effect of species distribution and population size. Conclusions Based on a single-country data sample, we support the relevance of the IWC Census methodology to produce estimates of wintering waterbird numbers and to calculate 1% thresholds for waterbird species, which we use to indicate nationally important wetland sites for future conservation and protection in the Czech Republic.

Black grouse in Czech Republic and its parasites

SummaryAccording to the newest data (2010), the state of the black grouse is in decline in the Czech Republic. One of the reasons for this decline is the parasitic infection. The examination of 170 faecal specimens disclosed 6 species of parasites. Helminth eggs were found in 50 % of the examined faecal specimens. The following eggs were found: cestode Hymenolepis spp. (28 %), with the highest prevalence (84 %) and mean intensity (1076 EPG) in spring; nematodes Trichostrongylus tenuis (24 %), and Ascaridia compar (3 %) with a mean intensity of 11 and 12 EPG, respectively. Coccidia infections were present in 1 % of faecal specimens only in spring, with an intensity of 35 OPG. However, in the following year, Eimeria lyruri was the most abundant parasite in the faecal specimens. During the second year of our research, the prevalence of E. lyruri was 28 %; the highest prevalence (67 %) was in summer with an intensity of up to 9433 OPG.

Long-term changes of small mammal communities in heterogenous landscapes of Central Europe

Long-term dynamics of small mammal communities are perennial themes in population ecology. However, comprehensive studies on the effect of environmental factors on population dynamics are still rare. Here, we aimed to analyze long-term data on Central European communities of small mammals occurring in two habitats that greatly differed in their structure, successional stages, and forest management. We found a richer community structure in young spruce plantations compared to mature European beech forests. In young spruce plantations, Myodes glareolus and Apodemus flavicollis abundances increased and Sorex araneus abundances decreased during the study period as a result of forest growth and management. Community structure in mature beech forests did not change significantly during the study period. Apodemus flavicollis and Myodes glareolus showed 3- and 5-year population cycles, respectively, and their abundances were simultaneously positively correlated with relative abundance of masts. Weather also played a role, while the effect of snow cover was pronounced only in mountain areas where it negatively affected Microtus agrestis and Sorex araneus abundances, temperature positively and rainfall negatively influenced Myodes glareolus and Apodemus flavicollis abundances across both studied habitats. Our findings document that a complex of environmental factors significantly affects the structure and dynamics of small mammal communities in Central Europe, and both local biotic and abiotic factors should be considered in future studies.