The Pan-European Common Bird Monitoring Scheme has brought together data from national monitoring... more The Pan-European Common Bird Monitoring Scheme has brought together data from national monitoring schemes from 18 European countries. This data has been used to provide European indices for 48 common bird species (24 woodland species, 24 farmland species). The indices were calculated for each country using the program TRIM, which estimates missing counts using Poisson regression. National indices were combined
L’any 2003 es va obtenir un primer i ampli conjunt d’índexs poblacionals d’espècies d’ocells comu... more L’any 2003 es va obtenir un primer i ampli conjunt d’índexs poblacionals d’espècies d’ocells comuns per al Programa de Seguiment Pan-Europeu d’Ocells Comuns, a partir dels resultats d’espècies reproductores en 18 països europeus. Per a l’anàlisi es van seleccionar espècies característiques de zones forestals, parcs i jardins, o d’hàbitats agrícoles d’Europa, 48 en total (24 de forestals, 24 de zones
The prevalences of heteroxenous parasites are influenced by the interplay of three main actors: h... more The prevalences of heteroxenous parasites are influenced by the interplay of three main actors: hosts, vectors, and the parasites themselves. We studied blood protists in the nesting populations of raptors in two different areas of the Czech Republic. Altogether, 788 nestlings and 258 adult Eurasian sparrowhawks (Accipiter nisus) and 321 nestlings and 86 adult common buzzards (Buteo buteo) were screened for parasites by the microscopic examination of blood smears and by cultivation. We examined the role of shared vectors and parasite phylogenetic relationships on the occurrence of parasites. In different years and hosts, trypanosome prevalence ranged between 1.9 and 87.2 %, that of Leucocytozoon between 1.9 and 100 %, and Haemoproteus between 0 and 72.7 %. Coinfections with Leucocytozoon and Trypanosoma, phylogenetically distant parasites but both transmitted by blackflies (Simuliidae), were more frequent than coinfections with Leucocytozoon and Haemoproteus, phylogenetically closely related parasites transmitted by different vectors (blackflies and biting midges (Ceratopogonidae), respectively). For example, 16.6 % buzzard nestlings were coinfected with Trypanosoma and Leucocytozoon, while only 4.8 % with Leucocytozoon and Haemoproteus and 0.3 % with Trypanosoma and Haemoproteus. Nestlings in the same nest tended to have the same infection status. Furthermore, prevalence increased with the age of nestlings and with Julian date, while brood size had only a weak negative/positive effect on prevalence at the individual/brood level. Prevalences in a particular avian host species also varied between study sites and years. All these factors should thus be considered while comparing prevalences from different studies, the impact of vectors being the most important. We conclude that phylogenetically unrelated parasites that share the same vectors tend to have similar distributions within the host populations of two different raptor species.
Rapid climatic change poses a threat to global biodiversity. There is extensive evidence that rec... more Rapid climatic change poses a threat to global biodiversity. There is extensive evidence that recent climatic change has affected animal and plant populations, but no indicators exist that summarise impacts over many species and large areas. We use data on long-term population trends of European birds to develop such an indicator. We find a significant relationship between interspecific variation in population trend and the change in potential range extent between the late 20 th and late 21 st centuries, forecasted by climatic envelope models. Our indicator measures divergence in population trend between bird species predicted by climatic envelope models to be favourably affected by climatic change and those adversely affected. The indicator shows a rapid increase in the past twenty years, coinciding with a period of rapid warming.
Concern that European forest biodiversity is depleted and declining has provoked widespread effor... more Concern that European forest biodiversity is depleted and declining has provoked widespread efforts to improve management practices. To gauge the success of these actions, appropriate monitoring of forest ecosystems is paramount. Multi-species indicators are frequently used to assess the state of biodiversity and its response to implemented management, but generally applicable and objective methodologies for species' selection are lacking. Here we use a nichebased approach, underpinned by coarse quantification of species' resource use, to objectively select species for inclusion in a pan-European forest bird indicator. We identify both the minimum number of species required to deliver full resource coverage and the most sensitive species' combination, and explore the trade-off between two key characteristics, sensitivity and redundancy, associated with indicators comprising different numbers of species. We compare our indicator to an existing forest bird indicator selected on the basis of expert opinion and show it is more representative of the wider community. We also present alternative indicators for regional and forest type specific monitoring and show that species' choice can have a significant impact on the indicator and consequent projections about the state of the biodiversity it represents. Furthermore, by comparing indicator sets drawn from currently monitored species and the full forest bird community, we identify gaps in the coverage of the current monitoring scheme. We believe that adopting this niche-based framework for species' selection supports the objective development of multi-species indicators and that it has good potential to be extended to a range of habitats and taxa.
The relationship between agricultural intensification and a decline in farmland bird populations ... more The relationship between agricultural intensification and a decline in farmland bird populations is well documented in Europe, but the results are mostly based on data from the western part of the continent. In the former socialist eastern and central European countries, political changes around 1990 resulted in a steep decline in the intensity of agriculture. Therefore, one would expect populations of farmland birds to have recovered under these conditions of lower agricultural intensity. We explored population trends of 19 farmland bird species in the Czech Republic between 1982 and 2003 using data from a large-scale monitoring scheme, and, additionally, we looked for relationships between such population changes and a number of variables describing the temporal development of Czech agriculture. Most farmland species declined during the focal period, and this decline was steepest in farmland specialists (Northern Lapwing Vanellus vanellus , Skylark Alauda arvensis , Linnet Carduelis cannabina and Yellowhammer Emberiza citrinella ). Although the intensity of agriculture was lower after than before 1990, the overall decline continued in most farmland bird species, albeit at a slower rate. The correlations between agricultural intensity and farmland bird decline showed opposite patterns to that found in other European studies, because bird populations were highest in years with the most intensive agriculture. We speculate that this pattern could have resulted from the impact of different driving forces causing farmland bird decline in different periods. The high intensity of agriculture could have caused the decline of the originally abundant populations before 1990. After 1990, the decreasing area of arable land could be the most important factor resulting in the continued decline of farmland bird populations. Our results demonstrate that the drivers of farmland bird population changes could differ across Europe, and thus investigations into the effect of farmland management in different parts of the continent are urgently required.
A species' susceptibility to environmental change might be predicted by its ecological and life-h... more A species' susceptibility to environmental change might be predicted by its ecological and life-history traits. However, the effects of such traits on long-term bird population trends have not yet been assessed using a comprehensive set of explanatory variables. Moreover, the extent to which phylogeny affects patterns in the interspecific variability of population changes is unclear. Our study focuses on the interspecific variability in long-term population trends and annual population fluctuations of 68 passerine species in the Czech Republic, assessing the effects of eight life-history and five ecological traits. Ordination of life-history traits of 68 species revealed a life-history gradient, from 'r-selected' (e.g. small body mass, short lifespan, high fecundity, large clutch size) to 'K-selected' species. r-selected species had more negative population trends than K-selected species, and seed-eaters declined compared with insectivores. We suggest that the r-selected species probably suffer from widespread environmental changes, and the seed-eaters from current changes in agriculture and land use. Populations of residents fluctuated more than populations of short-distance migrants, probably due to the effect of winter climatic variability. Variance partitioning at three taxonomic levels showed that whereas population trends, population fluctuations and habitat specialization expressed the highest variability at the species level, most life-history traits were more variable at higher taxonomic levels. These results explain the loss of statistical power in the relationship between life histories and population trends after controlling for phylogeny. However, we argue that a lack of significance after controlling for phylogeny should not reduce the value of such results for conservation purposes.
Recent studies show diVerences in population trends between groups of species occupying diVerent ... more Recent studies show diVerences in population trends between groups of species occupying diVerent habitats. In Czech birds, as well as in many other European countries, populations of forest species have increased, whereas populations of farmland species have declined. The aim of our study was to test whether population trends of particular species were related to Wner bird-habitat associations within farmland and forest birds. We assessed bird-habitat associations using canonical correspondence analysis based on data from a 400 km long transect across the Czech Republic. We calculated population trends of 62 bird species using log-linear models based on data from a large-scale annual monitoring scheme, which covers the time series from 1982 to 2005. Within forest birds, species with a closer association with lowland broad-leaved forest have had more positive population trends, whereas species with a closer association with montane and coniferous forest revealed more negative population trends. We attribute these opposite trends to the gradual replacement of coniferous forests by deciduous ones, which took place in the Czech Republic during recent decades. Our analyses revealed a hump-shaped relationship within farmland birds, species most closely associated with farmland habitat revealing the most negative trends, whereas species with intermediate association to farmland habitat showed the most positive population trends. Such a pattern can be explained by the abandonment of Biodivers Conserv (2008) 17:3307-3319 1 C previously cultivated areas followed by the spread of unmanaged meadows and scrubland. Changes in quantity or quality of preferred habitats may thus represent major drivers of observed bird population changes.
Numerous studies have shown that climate changes associated with increasing global temperature af... more Numerous studies have shown that climate changes associated with increasing global temperature affect bird species. For instance, long-distance migrants are not able to respond adequately to rapid advances in spring phenology, and thus their populations decline due to lower breeding performance. Moreover, many species in the Northern Hemisphere have shifted their northern breeding range boundaries further north. However, studies focusing on bird populations at the scale of individual countries, which are responsible for creating environmental policies, are rather scarce. We hypothesized that bird species with different European latitudinal breeding distributions would have different long-term population trends in the Czech Republic, a small central European country, as a result of range dynamics caused by increasing spring temperature. In accordance with this prediction, the results of an analysis based on large-scale monitoring data (from 1982 to 2006) showed that species with more northern latitudinal distributions had more negative population trends in the Czech Republic. However, the strength of the relationship depended on the approach used for characterization of the species latitudinal distributions. When a phylogenetic regression was applied, the only significant explanatory variable was the latitudinal distribution expressed in categories defined by species range areas in different latitudinal bands. A more detailed analysis showed that southern and northern species groups have opposite population trajectories: the former increased and the latter declined throughout the study period. The effect of climate change remained significant when habitat association and the migratory strategy of each species were taken into account. However, it is difficult to determine whether climate change or habitat change is the more important driver of long-term trends in bird populations as the effects of both factors are dependent on interspecific variability in levels of species specialization.
We explore population trends of widespread and common woodland birds using data from an extensive... more We explore population trends of widespread and common woodland birds using data from an extensive European network of ornithologists for the period 1980-2003. We show considerable differences exist in the European trends of species according to the broad habitat they occupy and the degree to which they specialize in habitat use. On average, common forest birds are in shallow decline at a European scale; common forest birds declined by 13%, and common forest specialists by 18%, from 1980 to 2003. In comparison, populations of common specialists of farmland have declined moderately, falling on average by 28% from 1980 to 2003. These patterns contrast with that shown by generalist species whose populations have been roughly stable over the same period, their overall index increasing by 3%. There was some evidence of regional variation in the population trends of these common forest species. The most obvious pattern was the greater stability of population trends in Eastern Europe compared with other regions considered. Among common forest birds, long-distance migrants and residents have on average declined most strongly, whereas shortdistance migrants have been largely stable, or have increased. There was some evidence to suggest that ground-or low-nesting species have declined more strongly on average, as have forest birds with invertebrate diets. Formal analysis of the species trends confirmed the influence of habitat use, habitat specialization and nest-site; the effects of region and migration strategy were less clear-cut. There was also evidence to show that year-to-year variation in individual species trends at a European scale was influenced by cold winter weather in a small number of species. We recommend that the species trend information provided by the new pan-European scheme should be used alongside existing mechanisms to review the conservation status of European birds. The analysis also allows us to reappraise the role of common forest bird populations as a potential barometer of wider forest health. The new indicator appears to be a useful indicator of the state of widespread European forest birds and might prove to be a useful surrogate for trends in forest biodiversity and forest health, but more work is likely to be needed to understand the interaction between bird populations and their drivers in forest.
Biodiversity is undergoing unprecedented global decline. Efforts to slow this rate have focused f... more Biodiversity is undergoing unprecedented global decline. Efforts to slow this rate have focused foremost on rarer species, which are at most risk of extinction. Less interest has been paid to more common species, despite their greater importance in terms of ecosystem function and service provision. How rates of decline are partitioned between common and less abundant species remains unclear. Using a 30-year data set of 144 bird species, we examined Europe-wide trends in avian abundance and biomass. Overall, avian abundance and biomass are both declining with most of this decline being attributed to more common species, while less abundant species showed an overall increase in both abundance and biomass. If overall avian declines are mainly due to reductions in a small number of common species, conservation efforts targeted at rarer species must be better matched with efforts to increase overall bird numbers, if ecological impacts of birds are to be maintained.
Global and regional targets to reduce the rate of biodiversity loss bring with them the need to m... more Global and regional targets to reduce the rate of biodiversity loss bring with them the need to measure the state of nature and how it is changing. A number of different biodiversity indicators have been developed in response and here we consider bird population indicators in Europe. Birds are often used as surrogates for other elements of biodiversity because they are so well known and well studied, and not for their unique intrinsic value as environmental indicators. Yet, in certain situations and at particular scales, trends in bird populations correlate with those of other taxa making them a valuable biodiversity indicator with appropriate caveats. In this paper, we look at two case studies, in the UK and Europe as a whole, where headline bird indicators, that is, summary statistics based on bird population trends, have been developed and used to inform and assist policy makers.
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Papers by Petr Voříšek