Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked eff... more Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked effect on the timing of spring migration of birds. It has however been suggested that long‐distance migrants wintering in Africa could respond less to NAO than short‐distance migrants wintering in Europe, making them more vulnerable to climatic changes. We studied whether migratory boreal and arctic bird species returning from different wintering areas show differences in responses to the NAO in the timing of their spring migration. We used data on 75 species from two bird observatories in northern Europe (60°N). By extending the examination to the whole distribution of spring migration and to a taxonomically diverse set of birds, we aimed at finding general patterns of the effects of climate fluctuation on the timing of avian migration. Most species arrived earlier after winters with high NAO index. The degree of NAO‐response diminished with the phase of migration: the early part of a spec...
We studied the relationship between temperature and the coexistence of great tit Parus major and ... more We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring tempera...
We studied the consequences of human disturbance and gull predation on brood survival of velvet s... more We studied the consequences of human disturbance and gull predation on brood survival of velvet scoter Melanitta fusca in the Archipelago of South-West Finland in 1990 and 1991. Each brood was exposed to disturbance by boats on average 8·5 times a day in 1990 and 3·5 ...
Population consequences of parasites in wild birds are rarely documented. One exception is the de... more Population consequences of parasites in wild birds are rarely documented. One exception is the decline of British finch populations due to an epidemic caused by the protozoan parasite Trichomonas gallinae. Finch trichomonosis has recently spread from the UK to northern Europe, but its consequences for local finch populations have not been studied. We assessed the extent to which the trichomonosis epidemic affected the Finnish population sizes of European Greenfinch Chloris chloris, Common Chaffinch Fringilla coelebs and a control species, Great Tit Parus major, and the body condition of Greenfinches. The disease was first documented in Finland in 2008 and epidemics were observed mainly in southwestern Finland. Greenfinches showed a significant decline of 47% in breeding numbers and 65% in wintering numbers in southern Finland during 2006– 2010. Breeding Chaffinch numbers showed a slight decline (4%) during the same study period that was significant only in central Finland. Great Tit did not show a significant change in breeding numbers. During the initial disease epidemic the body condition of all demographic groups of Greenfinches decreased equally, which suggests that the disease was not selective in respect of age or sex. There were no encounters of Finnishringed Greenfinches or Chaffinches in the UK, which could indicate that the parasite has not necessarily been transferred directly from the UK, but perhaps by migrants from Sweden and Germany.
Current climate change is affecting the timing of life-history events of birds, such as the timin... more Current climate change is affecting the timing of life-history events of birds, such as the timing of spring arrival at the breeding grounds. Interspecific differences in the advancement of spring migration have hitherto been attributed to differences in exposure to climatic variables in winter or on migration, without a more detailed consideration of sex-specific differences in the timing and extent of migration. Since males and females migrate during different times of the season or may segregate into different wintering grounds, we expect climate change to differentially affect the arrival timing of males and females. Furthermore, sexual selection theory predicts that the degree of protandry (i.e. the time difference between male and female arrival) should increase when the forces of natural selection opposing early arrival relax and the earliest males benefit from improved mating opportunities. Here, we explore whether the degree of protandry has changed during a period of climatic warming using long-term phenological data collected at 5 North European bird observatories. We show for 4 sexually dichromatic songbird species that spring migration has generally advanced, but that the degree of protandry has not changed. Moreover, we provide evidence that variation in large-scale weather conditions, as reflected in the North Atlantic Oscillation (NAO) index, have not affected the degree of protandry. We hypothesize that a parallel shift in the timing of male and female migration may be due to similar phenotypic plastic responses of males and females to climatic changes or reflect a correlated selection response in males and females. In addition, we discuss the possibility that the observed variation in protandry could result from seasonal shifts in local environmental conditions under which birds of both sexes 'fall out' and are sampled.
How environmental factors influence population dynamics in long-distance migrants is complicated ... more How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal.
We studied the occurrence of laying gaps in free-living populations of the pied Xycatcher, Ficedu... more We studied the occurrence of laying gaps in free-living populations of the pied Xycatcher, Ficedula hypoleuca, and the great tit, Parus major, in a pollution gradient of a copper smelter in southwest Finland. Laying gaps were 2.8 times more common in F. hypoleuca than in P. major. The probability of laying gaps was highest in the heavily polluted zone and lowest in the unpolluted zone for both bird species. Cold weather at the time of laying increased the number of laying gaps in both species, but in P. major this eVect was most pronounced in the heavily polluted environment. In the most heavily polluted environment the laying gaps were more likely to occur near the beginning of the laying sequence in both species. The laying gap probability increased with increasing laying date in P. major but not in F. hypoleuca. We suggest that the increased number of laying gaps in the polluted environment results from limited Ca availability and the interference of heavy metals with Ca metabolism in laying females.
We modelled breeding dispersal of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca)... more We modelled breeding dispersal of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca) around a point source of heavy metals (a copper smelter). We tested for the effects of sex, age, breeding success and environmental pollution on breeding dispersal distances of F. hypoleuca females and males. Unlike many earlier studies on breeding dispersal, we took into account distance-dependent sampling bias by including in our model the recapture probabilities at different distances from the site of origin. Our results show that F. hypoleuca females disperse much farther (on average 7.9 km) from their breeding sites than what was previously thought. In contrast, males only disperse short distances (on average 190 m). Breeding success affected female breeding dispersal distances depending on female age: young females moved on average 8 km from their previous breeding place irrespective of their breeding success, while old females only seemed to move this far when their fledgling production was good. Females successful in their breeding dispersed as far as less successful females, or, among old birds, even farther. Females which dispersed long distances produced more fledglings after the movement than those staying near their previous breeding site. Degree of environmental pollution had no effect on female or male breeding dispersal distances. A polluted and unproductive environment does not seem to stimulate F. hypoleuca parents to move to more profitable territories.
Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their di... more Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. They function in pigmentation and as antioxidants. We studied the carotenoid profiles in a model food chain (plant-insect-bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. Birch leaves showed higher beta-carotene and, one of the birch species (Betula pendula), higher total carotenoids levels in the polluted area. There was no difference in the lutein concentration of caterpillars' food source, birch leaves, between the study areas. Autumnal moth larvae accumulated lutein more efficiently than beta-carotene while sawfly larvae accumulated beta-carotene over lutein. Because of different antioxidant profiles in different leaf chewing insects their sensitivity to pollution stress may differ. The lutein concentration of plasma and feathers of Great tit nestlings did not differ along the pollution gradient. The lack of difference in lutein concentration of autumnal moth larvae along pollution gradient may partly explain the lutein concentrations of Great tit nestlings, since the abundance of autumnal moth larvae peak during the nestling phase of Great tit. The lutein concentration of autumnal moth larvae was positively associated to circulating plasma lutein level of Great tit indicating the importance of carotenoid rich diet during the nestling phase. In addition, the higher the plasma lutein concentration the more lutein was deposited to feathers, irrespective of the other possible functions of lutein in nestlings. We found that carotenoid levels differed between the polluted and the unpolluted area especially at lower levels of food chain: in birches and in caterpillars.
Abstract Knowledge about the importance of physical habitat characteristics to the breeding site ... more Abstract Knowledge about the importance of physical habitat characteristics to the breeding site selection of birds is a prerequisite for understanding their breeding habitat ecology and distribution, as well as managing their habitats. Geographical information systems (GIS) and existing digital data archives provide new possibilities for the quantitative and cost-effective assessment of coastal breeding habitats of birds. We tested the applicability of GIS and digital data archives for the analysis of coastal bird habitats by conducting a multivariate analysis on the relationship between physical island characteristics and the breeding site selection of 15 species of ducks, waders, larids and alcids in 2001–2005 in the fragmented archipelago coast of south-western Finland. We used GIS and environmental databases containing shoreline, bathymetry and elevation data to calculate five physical parameters for 71 small islands and their vicinity. Island area was generally the most important factor determining the presence of the species, but also water depth, shore openness, and island elevation were important for some species. The differences and similarities in habitat preferences within and between species groups seem to reflect the breeding habitat ecology of the species. GIS and spatial data archives are becoming increasingly valuable for research and development, as well as administrative tasks. Our results indicate that physical island characteristics affect the breeding site selection and the distribution of our target species, and that GIS and digital data archives provide applicable information on the breeding habitats of coastal birds and thus function as a tool for conservation and management.
Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked eff... more Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked effect on the timing of spring migration of birds. It has however been suggested that long‐distance migrants wintering in Africa could respond less to NAO than short‐distance migrants wintering in Europe, making them more vulnerable to climatic changes. We studied whether migratory boreal and arctic bird species returning from different wintering areas show differences in responses to the NAO in the timing of their spring migration. We used data on 75 species from two bird observatories in northern Europe (60°N). By extending the examination to the whole distribution of spring migration and to a taxonomically diverse set of birds, we aimed at finding general patterns of the effects of climate fluctuation on the timing of avian migration. Most species arrived earlier after winters with high NAO index. The degree of NAO‐response diminished with the phase of migration: the early part of a spec...
We studied the relationship between temperature and the coexistence of great tit Parus major and ... more We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring tempera...
We studied the consequences of human disturbance and gull predation on brood survival of velvet s... more We studied the consequences of human disturbance and gull predation on brood survival of velvet scoter Melanitta fusca in the Archipelago of South-West Finland in 1990 and 1991. Each brood was exposed to disturbance by boats on average 8·5 times a day in 1990 and 3·5 ...
Population consequences of parasites in wild birds are rarely documented. One exception is the de... more Population consequences of parasites in wild birds are rarely documented. One exception is the decline of British finch populations due to an epidemic caused by the protozoan parasite Trichomonas gallinae. Finch trichomonosis has recently spread from the UK to northern Europe, but its consequences for local finch populations have not been studied. We assessed the extent to which the trichomonosis epidemic affected the Finnish population sizes of European Greenfinch Chloris chloris, Common Chaffinch Fringilla coelebs and a control species, Great Tit Parus major, and the body condition of Greenfinches. The disease was first documented in Finland in 2008 and epidemics were observed mainly in southwestern Finland. Greenfinches showed a significant decline of 47% in breeding numbers and 65% in wintering numbers in southern Finland during 2006– 2010. Breeding Chaffinch numbers showed a slight decline (4%) during the same study period that was significant only in central Finland. Great Tit did not show a significant change in breeding numbers. During the initial disease epidemic the body condition of all demographic groups of Greenfinches decreased equally, which suggests that the disease was not selective in respect of age or sex. There were no encounters of Finnishringed Greenfinches or Chaffinches in the UK, which could indicate that the parasite has not necessarily been transferred directly from the UK, but perhaps by migrants from Sweden and Germany.
Current climate change is affecting the timing of life-history events of birds, such as the timin... more Current climate change is affecting the timing of life-history events of birds, such as the timing of spring arrival at the breeding grounds. Interspecific differences in the advancement of spring migration have hitherto been attributed to differences in exposure to climatic variables in winter or on migration, without a more detailed consideration of sex-specific differences in the timing and extent of migration. Since males and females migrate during different times of the season or may segregate into different wintering grounds, we expect climate change to differentially affect the arrival timing of males and females. Furthermore, sexual selection theory predicts that the degree of protandry (i.e. the time difference between male and female arrival) should increase when the forces of natural selection opposing early arrival relax and the earliest males benefit from improved mating opportunities. Here, we explore whether the degree of protandry has changed during a period of climatic warming using long-term phenological data collected at 5 North European bird observatories. We show for 4 sexually dichromatic songbird species that spring migration has generally advanced, but that the degree of protandry has not changed. Moreover, we provide evidence that variation in large-scale weather conditions, as reflected in the North Atlantic Oscillation (NAO) index, have not affected the degree of protandry. We hypothesize that a parallel shift in the timing of male and female migration may be due to similar phenotypic plastic responses of males and females to climatic changes or reflect a correlated selection response in males and females. In addition, we discuss the possibility that the observed variation in protandry could result from seasonal shifts in local environmental conditions under which birds of both sexes 'fall out' and are sampled.
How environmental factors influence population dynamics in long-distance migrants is complicated ... more How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal.
We studied the occurrence of laying gaps in free-living populations of the pied Xycatcher, Ficedu... more We studied the occurrence of laying gaps in free-living populations of the pied Xycatcher, Ficedula hypoleuca, and the great tit, Parus major, in a pollution gradient of a copper smelter in southwest Finland. Laying gaps were 2.8 times more common in F. hypoleuca than in P. major. The probability of laying gaps was highest in the heavily polluted zone and lowest in the unpolluted zone for both bird species. Cold weather at the time of laying increased the number of laying gaps in both species, but in P. major this eVect was most pronounced in the heavily polluted environment. In the most heavily polluted environment the laying gaps were more likely to occur near the beginning of the laying sequence in both species. The laying gap probability increased with increasing laying date in P. major but not in F. hypoleuca. We suggest that the increased number of laying gaps in the polluted environment results from limited Ca availability and the interference of heavy metals with Ca metabolism in laying females.
We modelled breeding dispersal of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca)... more We modelled breeding dispersal of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca) around a point source of heavy metals (a copper smelter). We tested for the effects of sex, age, breeding success and environmental pollution on breeding dispersal distances of F. hypoleuca females and males. Unlike many earlier studies on breeding dispersal, we took into account distance-dependent sampling bias by including in our model the recapture probabilities at different distances from the site of origin. Our results show that F. hypoleuca females disperse much farther (on average 7.9 km) from their breeding sites than what was previously thought. In contrast, males only disperse short distances (on average 190 m). Breeding success affected female breeding dispersal distances depending on female age: young females moved on average 8 km from their previous breeding place irrespective of their breeding success, while old females only seemed to move this far when their fledgling production was good. Females successful in their breeding dispersed as far as less successful females, or, among old birds, even farther. Females which dispersed long distances produced more fledglings after the movement than those staying near their previous breeding site. Degree of environmental pollution had no effect on female or male breeding dispersal distances. A polluted and unproductive environment does not seem to stimulate F. hypoleuca parents to move to more profitable territories.
Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their di... more Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. They function in pigmentation and as antioxidants. We studied the carotenoid profiles in a model food chain (plant-insect-bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. Birch leaves showed higher beta-carotene and, one of the birch species (Betula pendula), higher total carotenoids levels in the polluted area. There was no difference in the lutein concentration of caterpillars' food source, birch leaves, between the study areas. Autumnal moth larvae accumulated lutein more efficiently than beta-carotene while sawfly larvae accumulated beta-carotene over lutein. Because of different antioxidant profiles in different leaf chewing insects their sensitivity to pollution stress may differ. The lutein concentration of plasma and feathers of Great tit nestlings did not differ along the pollution gradient. The lack of difference in lutein concentration of autumnal moth larvae along pollution gradient may partly explain the lutein concentrations of Great tit nestlings, since the abundance of autumnal moth larvae peak during the nestling phase of Great tit. The lutein concentration of autumnal moth larvae was positively associated to circulating plasma lutein level of Great tit indicating the importance of carotenoid rich diet during the nestling phase. In addition, the higher the plasma lutein concentration the more lutein was deposited to feathers, irrespective of the other possible functions of lutein in nestlings. We found that carotenoid levels differed between the polluted and the unpolluted area especially at lower levels of food chain: in birches and in caterpillars.
Abstract Knowledge about the importance of physical habitat characteristics to the breeding site ... more Abstract Knowledge about the importance of physical habitat characteristics to the breeding site selection of birds is a prerequisite for understanding their breeding habitat ecology and distribution, as well as managing their habitats. Geographical information systems (GIS) and existing digital data archives provide new possibilities for the quantitative and cost-effective assessment of coastal breeding habitats of birds. We tested the applicability of GIS and digital data archives for the analysis of coastal bird habitats by conducting a multivariate analysis on the relationship between physical island characteristics and the breeding site selection of 15 species of ducks, waders, larids and alcids in 2001–2005 in the fragmented archipelago coast of south-western Finland. We used GIS and environmental databases containing shoreline, bathymetry and elevation data to calculate five physical parameters for 71 small islands and their vicinity. Island area was generally the most important factor determining the presence of the species, but also water depth, shore openness, and island elevation were important for some species. The differences and similarities in habitat preferences within and between species groups seem to reflect the breeding habitat ecology of the species. GIS and spatial data archives are becoming increasingly valuable for research and development, as well as administrative tasks. Our results indicate that physical island characteristics affect the breeding site selection and the distribution of our target species, and that GIS and digital data archives provide applicable information on the breeding habitats of coastal birds and thus function as a tool for conservation and management.
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Papers by Esa Lehikoinen