Impacts of trichomonosis epidemics on Greenfinch Chloris chloris and Chaffinch Fringilla coelebs populations in Finland

Diversity and Distributions

Foppen

Lindström

et al. 2016

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Aim Changes in climate and land use practices have been found to affect animal populations in different parts of the world. These studies have typically been conducted during the breeding season, whereas the non‐breeding season (hereafter ‘winter’) has received much less attention. Changes in regional winter abundances could be caused by changes in overall population sizes and/or redistribution of populations. We tested these mechanisms for terrestrial winter bird population changes in Northern Europe and explored the role of climate change and species habitat preference. Location The Netherlands, Denmark, Sweden, Finland. Methods We used winter bird counts from four countries conducted annually between 15 December and 20 January in 1980/1981–2013/2014. We report national population trends for 50 species for which a trend could be calculated in at least three of the countries. We analysed country‐specific population growth rates in relation to species’ climatic summer and winter niches, habitat preference and migratory behaviour. Results Species breeding in colder (typically northern) areas showed more negative winter population trends than species breeding in warmer areas. Regional winter population trends were negatively correlated with characteristics of their winter climatic niche: populations in the colder part of their winter distribution increased in abundance, whereas populations in the warmer part of their winter distribution decreased. Woodland species tended to do better than farmland species. Migratory behaviour did not explain variation in population trends. Main conclusions The generally decreasing winter population trends of cold‐dwelling breeding species probably reflect the general decline in population sizes of these species. In contrast, increasing winter population trends for populations in the colder parts of the winter distribution indicate a redistribution of wintering individuals towards the north‐east. Both these patterns are likely caused by climate change.

Section: Discussionmentioning

confidence: 99%

Large‐scale climatic drivers of regional winter bird population trends

Diversity and Distributions

Foppen

Lindström

et al. 2016

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“…Due to different detection probabilities of the species, the resulting survey data are not suitable for estimating absolute abundances. They are however appropriate to reliably describe and compare changes in relative abundance (which will be used in this study) and distribution of birds across space and time (Lehikoinen et al ., ; Fraixedas et al ., ). For the breeding counts, the observations are transformed into pairs (e.g.…”

Section: Methodsmentioning

confidence: 98%

“…For this study, we use a unique dataset consisting on bird observations collected using the line transect method from across Finland starting from the early 1970s (Virkkala & Lehikoinen, 2014). The line transect method consists of a one-visit survey whereby all birds are counted along a transect band on average 10 km long for the winter counts (n = 2661 transects) and typically 3-6 km long for the breeding season counts (n = 3555 transects) on a pre-determined location (more details in Lehikoinen et al, 2013;Lehikoinen & Virkkala, 2016).…”

Section: Line Transect Datamentioning

confidence: 99%

Are winter and breeding bird communities able to track rapid climate change? Lessons from the high North

Santangeli

Diversity and Distributions

2017

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Aim Climate change is a major threat to biodiversity and a major factor underlying observed shifts in species distribution, abundance and phenology. Research effort on climate change impacts on species has often been based on single‐species studies focused on a single season, typically the breeding season, of species life cycles. We test how well winter and breeding bird communities are able to track climate change. Location Finland. Methods We use a dataset consisting of bird counts from the winter and the breeding period spanning over four decades and a 1000 km latitudinal gradient across Finland, Northern Europe. We use the bird count data in combination with a species‐specific average temperature index to derive a functional index, the Community Temperature Index (CTI), which provides a measure of the relative temperature average of a community. Results We show that the CTI of the winter bird community (CTIw) in Finland has increased significantly over the past four decades, but not as fast as the average winter temperature. Across Finland, CTIw decreased towards the north and the east of the country and increased with increasing temperature. Further, we show that change in CTI through time (from 1970s–1980s to 2000–2014) was similar between the winter and the breeding communities. Main conclusions Overall, our results suggest that while the winter and breeding bird communities are, to a certain level, tracking increasing temperatures, the magnitude of temperature change is multiple times greater than the magnitude of community shifts. This is particularly true for the winter birds that are facing the most rapid temperature shifts. Our findings shed light on the importance of assessing and eventually addressing the effects of rapid climate warming beyond the breeding season of species life cycles.

“…Although the counting method described above does not reveal the absolute unbiased abundances of species, because of species‐specific differences in detectability, the selected data reliably describe variation in the general distribution of birds around the country and in different environments (Koskimies and Väisänen , Lehikoinen et al ). Habitat data (habitats of the counted birds as well as the amount of habitat along the routes) were first gathered in 1986 including information for eight land‐cover categories: a) dumping ground or fur farm; b) urban settlement; c) rural settlement; d) arable land; e) forest; f) clear‐cut area or stand of saplings; g) reed‐bed or shore scrub; and h) other.…”

Section: Methodsmentioning

confidence: 99%

Impacts of climate and land‐use change on wintering bird populations in Finland

Fraixedas

Journal of Avian Biology

Lindén

2014

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Few studies have covered both the eff ects of climate and land-use change on animal populations under a single framework. Besides, the scarce multi-species studies conducted have focused on breeding data, and there is little information published on changes in wintering populations. Here, we relate the pattern of long-term temporal trends of wintering bird populations in Finland, north Europe, to covariates associated with climate and land-use change. Finnish wintering populations have been monitored using ca 10 km winter bird census routes ( Ͼ 420 routes counted annually) during 1959 -2012. Population trends of 63 species were related to migratory strategy, urbanity, and thermal niche measured as species-specifi c centre of gravity of the wintering distribution. Waterbird trends have shown a marked increase compared to landbirds. Among landbirds, forest species have suff ered severe declines, whereas urban species have considerably increased in their wintering numbers. To follow up these results, we produced three multi-species indices (for waterbirds, forest and urban species, respectively), which can improve our ability to detect and monitor the specifi c consequences of climate change and changes in land-use, but at the same time act as a feedback to track the conservation status of the species. Our results suggest that waterbirds are responding to climate change, given their dependence on open water and the correlation with early-winter temperature over the last decades. On the other hand, we believe trends of landbirds have been mainly driven by human-induced land-use changes. While urban species have likely benefi ted from the increase of supplementary feeding, forest species have probably suff ered from the loss of native habitats.