During migratory endurance flights, which are energetically very demanding, migrants have to deal... more During migratory endurance flights, which are energetically very demanding, migrants have to deal with prolonged elevated generation of reactive oxygen species (ROS). To limit the damaging actions that ROS have on lipids and proteins, migrating birds are known to upregulate their antioxidant defence system. However, there may be additional ways to limit oxidative damage incurred from flying. Migratory endurance flights are fuelled mainly with fatty acids (FAs), and the risk of their peroxidation (resulting in oxidative lipid damage) increases with the number of double bonds in a FA, with polyunsaturated FAs (2 or more double bonds, PUFAs) being most peroxidation-prone. By fuelling their flights with relatively few PUFAs, migratory birds could thus limit oxidative lipid damage. Within migratory birds, there is considerable variation in the length of their flights, with nocturnal migrants making lengthier flight bouts, thus more likely to experience lengthier periods of elevated ROS production, than diurnal migrants. However, whether migrants making lengthier flights incur more oxidative lipid damage is unknown. Neither is it known whether flight length and FA composition are associated. Therefore, we determined plasmatic malondialdehyde level, a marker of oxidative lipid damage, and FA composition of three nocturnal and two diurnal migrant species caught at an autumn stopover site. We found little inter-specific variation in malondialdehyde level, indicating that the amount of oxidative lipid damage was comparable across the species. In contrast, the species strongly differed in their plasmatic FA composition. The nocturnal migrants had significantly lower relative PUFA levels than both diurnal migrants, an effect mainly attributable to linoleic acid, an essential (strictly dietary) FA. Consequently, the susceptibility of plasmatic FAs to lipid peroxidation was significantly lower in the nocturnal than diurnal migrants. Because in birds, energy expenditure during flight decreases with the degree of FA unsaturation, we interpret our observation of lower PUFA levels in nocturnal migrants as support for the idea that utilizing PUFA-poor fuel can help migrating birds to curb oxidative lipid damage.
The ongoing wide‐scale introduction of nonnative plants across the world may negatively influence... more The ongoing wide‐scale introduction of nonnative plants across the world may negatively influence native invertebrate fauna, due to a lack of coevolved traits related to the novel plants, e.g., unique phytochemicals or shifted phenology. Nonnative plants, specifically trees, are common in urban environments, areas that already pose novel habitats to plants and wildlife through a wide array of anthropogenic factors. For example, impervious surfaces contribute to increased ambient temperatures, the so‐called urban heat island effect (UHI), which can affect local plant phenology. Yet, few studies have simultaneously studied the effects of urbanization and tree species origin on urban invertebrate communities. We measured the city‐level UHI and phenology of nine native and seven nonnative tree species in five city‐center parks in southern Sweden, as well as four common native species in a rural control forest. We quantified the abundance of invertebrates on a subset of native and nonnative tree species through shake sampling, sticky traps, and frass collection. In the urban environment, nonnative trees hosted significantly fewer invertebrates compared to native trees. Furthermore, the nonnative trees had a delayed phenology compared to native species, while the peak of caterpillars associated with the subset of trees surveyed for this measure was significantly earlier compared to that of the native species studied. The effect of tree species origin on urban invertebrate abundance was of a greater magnitude (effect size) than the effect of urbanization on invertebrate abundance in native tree hosts. Hence, the results indicate that the impact of nonnative vegetation may be a stronger driver of invertebrate declines in urban areas than other factors. As the effect of species origin on tree phenology was at a level comparable to the urban effect, increasing prevalence of nonnative vegetation can potentially obscure effects of urbanization on phenology in large‐scale studies, as well as induce mismatches to invertebrate populations. Since parks harbor a large proportion of urban biodiversity, native trees play a crucial role in such habitats and should not be considered replaceable by nonnative species in terms of conservation value.
Additional file 5. Results of linear mixed-effects models used to test for relationships between ... more Additional file 5. Results of linear mixed-effects models used to test for relationships between nestling tarsus length on days 6 and 12 and survival in the nest.
Additional file 4. Results of linear mixed-effects models to test for relationships between yolk ... more Additional file 4. Results of linear mixed-effects models to test for relationships between yolk composition and phenotypic traits on day 12.
Urban environments are expanding rapidly, and with urbanization come both challenges and opportun... more Urban environments are expanding rapidly, and with urbanization come both challenges and opportunities for wildlife. Challenges include combating the anthropogenic disturbances such as light, noise and air pollution and lower availability of natural food sources. The benefits are many, including the availability of anthropogenic food sources, breeding boxes and warmer temperatures. Thus, depending on the context, urbanization can have both positive and negative effects on fitness related traits. It is well known that early-life conditions can have lifelong implications on fitness; little is however known about development in urban environments. We reciprocally cross-fostered urban and rural nestling great tits (Parus major L.) to study how growing up in an urban versus rural habitat affected telomere length (TL)—a suggested biomarker of longevity. We show, for the first time, that growing up in an urban environment significantly shortens TL, independently of natal origin (i.e. urban or rural). This implies that the urban environment imposes a challenge to developing birds, with potentially irreversible effects on lifespan
Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. ... more Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. Although differences have been reported in several phenotypic traits (e.g. morphology, physiology and behaviour) between urban and rural populations, it is poorly understood whether this affects individual fitness. Telomere dynamics are posited as one possible mechanism underlying senescence and mortality. It was recently shown that telomere shortening is accelerated when growing up in an urban, compared with a rural, environment. However, the implications of accelerated telomere attrition for fitness are still unclear. Here, we examine the relationship between telomere length (TL) and survival in a bird common to urban and rural environments, and during both early and later life. The results reveal that TL is a strong predictor of post-fledging survival and recruitment in both habitats but, crucially, selective disappearance of individuals with short telomeres early in life is more pronounced in the urban environment, resulting in a longer average TL among the adult population. However, following recruitment, we found no difference in the relationship between TL and survival between the urban and rural environments. This indicates that the urban environment has negative effects in early life, while during later life the benefits could potentially outweigh the costs
The integration and synthesis of the data in different areas of science is drastically slowed and... more The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Further, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-terms studies of birds, we have created the SPI-Birds Network and Database (www.spibirds.org) – a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within a year of the establishment, SPI-Birds counts 120 members working on more than 80 populations, w...
The large-scale impact of urbanization on wildlife is rather well documented; however, the mechan... more The large-scale impact of urbanization on wildlife is rather well documented; however, the mechanisms underlying the effects of urban environments on animal physiology and behaviour are still poorly understood. Here, we focused on one major urban pollutant – artificial light at night (ALAN) – and its effects on the capacity to mount an innate immune response in wild great tit (Parus major) nestlings. Exposure to ALAN alters circadian rhythms of physiological processes, by disrupting the nocturnal production of the hormone melatonin. Nestlings were exposed to a light source emitting 3 lx for seven consecutive nights. Subsequently, nestlings were immune challenged with a lipopolysaccharide injection, and we measured haptoglobin and nitric oxide levels pre- and post-injection. Both haptoglobin and nitric oxide are important markers for innate immune function. We found that ALAN exposure altered the innate immune response, with nestlings exposed to ALAN having lower haptoglobin and high...
Urbanization is next to global warming the largest threat to biodiversity. Indeed, it is becoming... more Urbanization is next to global warming the largest threat to biodiversity. Indeed, it is becoming increasingly evident that many bird species get locally extinct as a result of urban development. However, many bird species benefit from urbanization, especially through the abundance of human-provided resources, and increase in abundance and densities. These birds are intriguing to study in relation to its resilience and adaption to urban environments, but also in relation to its susceptibility and the potential costs of urban life. This Research Topic consisting of 30 articles (one review, two meta-analyzes and 27 original data papers) provides insights into species and population responses to urbanization through diverse lenses, including biogeography, community ecology, behaviour, life history evolution, and physiology
Most avian migrants alternate flight bouts, characterized by high metabolic rates, with stopovers... more Most avian migrants alternate flight bouts, characterized by high metabolic rates, with stopovers, periods of fuel replenishment through hyperphagia. High-energy metabolism and excessive calorie intake shift the balance between damaging prooxidants and antioxidants toward the former. Hence, migration likely affects the oxidative balance of birds. Migratory flight indeed appears to cause oxidative damage; however, whether migration affects the oxidative state of birds at stopover is unclear. Therefore, we compared total nonenzymatic antioxidant capacity (AOX) and malondialdehyde concentration (MDA; a measure of lipid peroxidation) in the plasma of migrant and resident common blackbirds. We also determined plasmatic uric acid (UA) and fatty acid (FA) concentrations and calculated a FA peroxidation index. Birds were sampled during autumn migration at a stopover site that also supports a sedentary blackbird population. Migrants had higher AOX than residents, also after correcting for UA concentration. Migrants tended to have higher FA peroxidation indexes than residents, indicating that the energy source of migrants contains higher concentrations of peroxidizable FAs. However, the two groups did not differ in MDA concentration, also not after correcting for peroxidation index. Peroxidation-corrected MDA concentration was negatively correlated with UA-corrected AOX. In other words, individuals with low nonenzymatic AOX suffered more from lipid peroxidation than individuals with high nonenzymatic AOX. These results together indicate that migrant blackbirds invest in antioxidant defenses to reduce oxidative damage to lipids, likely representing an adaptation to diminish the physiological costs of migration.
During migratory endurance flights, which are energetically very demanding, migrants have to deal... more During migratory endurance flights, which are energetically very demanding, migrants have to deal with prolonged elevated generation of reactive oxygen species (ROS). To limit the damaging actions that ROS have on lipids and proteins, migrating birds are known to upregulate their antioxidant defence system. However, there may be additional ways to limit oxidative damage incurred from flying. Migratory endurance flights are fuelled mainly with fatty acids (FAs), and the risk of their peroxidation (resulting in oxidative lipid damage) increases with the number of double bonds in a FA, with polyunsaturated FAs (2 or more double bonds, PUFAs) being most peroxidation-prone. By fuelling their flights with relatively few PUFAs, migratory birds could thus limit oxidative lipid damage. Within migratory birds, there is considerable variation in the length of their flights, with nocturnal migrants making lengthier flight bouts, thus more likely to experience lengthier periods of elevated ROS production, than diurnal migrants. However, whether migrants making lengthier flights incur more oxidative lipid damage is unknown. Neither is it known whether flight length and FA composition are associated. Therefore, we determined plasmatic malondialdehyde level, a marker of oxidative lipid damage, and FA composition of three nocturnal and two diurnal migrant species caught at an autumn stopover site. We found little inter-specific variation in malondialdehyde level, indicating that the amount of oxidative lipid damage was comparable across the species. In contrast, the species strongly differed in their plasmatic FA composition. The nocturnal migrants had significantly lower relative PUFA levels than both diurnal migrants, an effect mainly attributable to linoleic acid, an essential (strictly dietary) FA. Consequently, the susceptibility of plasmatic FAs to lipid peroxidation was significantly lower in the nocturnal than diurnal migrants. Because in birds, energy expenditure during flight decreases with the degree of FA unsaturation, we interpret our observation of lower PUFA levels in nocturnal migrants as support for the idea that utilizing PUFA-poor fuel can help migrating birds to curb oxidative lipid damage.
The ongoing wide‐scale introduction of nonnative plants across the world may negatively influence... more The ongoing wide‐scale introduction of nonnative plants across the world may negatively influence native invertebrate fauna, due to a lack of coevolved traits related to the novel plants, e.g., unique phytochemicals or shifted phenology. Nonnative plants, specifically trees, are common in urban environments, areas that already pose novel habitats to plants and wildlife through a wide array of anthropogenic factors. For example, impervious surfaces contribute to increased ambient temperatures, the so‐called urban heat island effect (UHI), which can affect local plant phenology. Yet, few studies have simultaneously studied the effects of urbanization and tree species origin on urban invertebrate communities. We measured the city‐level UHI and phenology of nine native and seven nonnative tree species in five city‐center parks in southern Sweden, as well as four common native species in a rural control forest. We quantified the abundance of invertebrates on a subset of native and nonnative tree species through shake sampling, sticky traps, and frass collection. In the urban environment, nonnative trees hosted significantly fewer invertebrates compared to native trees. Furthermore, the nonnative trees had a delayed phenology compared to native species, while the peak of caterpillars associated with the subset of trees surveyed for this measure was significantly earlier compared to that of the native species studied. The effect of tree species origin on urban invertebrate abundance was of a greater magnitude (effect size) than the effect of urbanization on invertebrate abundance in native tree hosts. Hence, the results indicate that the impact of nonnative vegetation may be a stronger driver of invertebrate declines in urban areas than other factors. As the effect of species origin on tree phenology was at a level comparable to the urban effect, increasing prevalence of nonnative vegetation can potentially obscure effects of urbanization on phenology in large‐scale studies, as well as induce mismatches to invertebrate populations. Since parks harbor a large proportion of urban biodiversity, native trees play a crucial role in such habitats and should not be considered replaceable by nonnative species in terms of conservation value.
Additional file 5. Results of linear mixed-effects models used to test for relationships between ... more Additional file 5. Results of linear mixed-effects models used to test for relationships between nestling tarsus length on days 6 and 12 and survival in the nest.
Additional file 4. Results of linear mixed-effects models to test for relationships between yolk ... more Additional file 4. Results of linear mixed-effects models to test for relationships between yolk composition and phenotypic traits on day 12.
Urban environments are expanding rapidly, and with urbanization come both challenges and opportun... more Urban environments are expanding rapidly, and with urbanization come both challenges and opportunities for wildlife. Challenges include combating the anthropogenic disturbances such as light, noise and air pollution and lower availability of natural food sources. The benefits are many, including the availability of anthropogenic food sources, breeding boxes and warmer temperatures. Thus, depending on the context, urbanization can have both positive and negative effects on fitness related traits. It is well known that early-life conditions can have lifelong implications on fitness; little is however known about development in urban environments. We reciprocally cross-fostered urban and rural nestling great tits (Parus major L.) to study how growing up in an urban versus rural habitat affected telomere length (TL)—a suggested biomarker of longevity. We show, for the first time, that growing up in an urban environment significantly shortens TL, independently of natal origin (i.e. urban or rural). This implies that the urban environment imposes a challenge to developing birds, with potentially irreversible effects on lifespan
Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. ... more Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. Although differences have been reported in several phenotypic traits (e.g. morphology, physiology and behaviour) between urban and rural populations, it is poorly understood whether this affects individual fitness. Telomere dynamics are posited as one possible mechanism underlying senescence and mortality. It was recently shown that telomere shortening is accelerated when growing up in an urban, compared with a rural, environment. However, the implications of accelerated telomere attrition for fitness are still unclear. Here, we examine the relationship between telomere length (TL) and survival in a bird common to urban and rural environments, and during both early and later life. The results reveal that TL is a strong predictor of post-fledging survival and recruitment in both habitats but, crucially, selective disappearance of individuals with short telomeres early in life is more pronounced in the urban environment, resulting in a longer average TL among the adult population. However, following recruitment, we found no difference in the relationship between TL and survival between the urban and rural environments. This indicates that the urban environment has negative effects in early life, while during later life the benefits could potentially outweigh the costs
The integration and synthesis of the data in different areas of science is drastically slowed and... more The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Further, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-terms studies of birds, we have created the SPI-Birds Network and Database (www.spibirds.org) – a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within a year of the establishment, SPI-Birds counts 120 members working on more than 80 populations, w...
The large-scale impact of urbanization on wildlife is rather well documented; however, the mechan... more The large-scale impact of urbanization on wildlife is rather well documented; however, the mechanisms underlying the effects of urban environments on animal physiology and behaviour are still poorly understood. Here, we focused on one major urban pollutant – artificial light at night (ALAN) – and its effects on the capacity to mount an innate immune response in wild great tit (Parus major) nestlings. Exposure to ALAN alters circadian rhythms of physiological processes, by disrupting the nocturnal production of the hormone melatonin. Nestlings were exposed to a light source emitting 3 lx for seven consecutive nights. Subsequently, nestlings were immune challenged with a lipopolysaccharide injection, and we measured haptoglobin and nitric oxide levels pre- and post-injection. Both haptoglobin and nitric oxide are important markers for innate immune function. We found that ALAN exposure altered the innate immune response, with nestlings exposed to ALAN having lower haptoglobin and high...
Urbanization is next to global warming the largest threat to biodiversity. Indeed, it is becoming... more Urbanization is next to global warming the largest threat to biodiversity. Indeed, it is becoming increasingly evident that many bird species get locally extinct as a result of urban development. However, many bird species benefit from urbanization, especially through the abundance of human-provided resources, and increase in abundance and densities. These birds are intriguing to study in relation to its resilience and adaption to urban environments, but also in relation to its susceptibility and the potential costs of urban life. This Research Topic consisting of 30 articles (one review, two meta-analyzes and 27 original data papers) provides insights into species and population responses to urbanization through diverse lenses, including biogeography, community ecology, behaviour, life history evolution, and physiology
Most avian migrants alternate flight bouts, characterized by high metabolic rates, with stopovers... more Most avian migrants alternate flight bouts, characterized by high metabolic rates, with stopovers, periods of fuel replenishment through hyperphagia. High-energy metabolism and excessive calorie intake shift the balance between damaging prooxidants and antioxidants toward the former. Hence, migration likely affects the oxidative balance of birds. Migratory flight indeed appears to cause oxidative damage; however, whether migration affects the oxidative state of birds at stopover is unclear. Therefore, we compared total nonenzymatic antioxidant capacity (AOX) and malondialdehyde concentration (MDA; a measure of lipid peroxidation) in the plasma of migrant and resident common blackbirds. We also determined plasmatic uric acid (UA) and fatty acid (FA) concentrations and calculated a FA peroxidation index. Birds were sampled during autumn migration at a stopover site that also supports a sedentary blackbird population. Migrants had higher AOX than residents, also after correcting for UA concentration. Migrants tended to have higher FA peroxidation indexes than residents, indicating that the energy source of migrants contains higher concentrations of peroxidizable FAs. However, the two groups did not differ in MDA concentration, also not after correcting for peroxidation index. Peroxidation-corrected MDA concentration was negatively correlated with UA-corrected AOX. In other words, individuals with low nonenzymatic AOX suffered more from lipid peroxidation than individuals with high nonenzymatic AOX. These results together indicate that migrant blackbirds invest in antioxidant defenses to reduce oxidative damage to lipids, likely representing an adaptation to diminish the physiological costs of migration.
Uploads