Alternative migratory strategies can coexist within animal populations and species. Anthropogenic... more Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade‐offs associated with four different movement strategies (long‐ and short‐distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long‐distance migration towards year‐round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with triaxial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity‐related energy expenditure. Additionally, we monitored nesting colonies to assess individ...
Background Migration phenology is shifting for many long-distance migrants due to global climate ... more Background Migration phenology is shifting for many long-distance migrants due to global climate change, however the timing and duration of migration may influence the environmental conditions individuals encounter, with potential fitness consequences. Species with asynchronous migrations, i.e., with variability in migration timing, provide an excellent opportunity to investigate how of the conditions individuals experience during migration can vary and affect the migratory performance, route, and destination of migrants. Methods Here, we use GPS tracking and accelerometer data to examine if timing of autumn migration influences the migratory performance (duration, distance, route straightness, energy expenditure) and migration destinations of a long-distance, asynchronous, migrant, the white stork (Ciconia ciconia). We also compare the weather conditions (wind speed, wind direction, and boundary layer height) encountered on migration and examine the influence of wind direction on s...
Anthropogenic structures are increasingly encroaching wildlife habitats, creating conflicts betwe... more Anthropogenic structures are increasingly encroaching wildlife habitats, creating conflicts between humans and animals. Scaling up renewable energy requires new infrastructures such as power lines, that cause high mortality among birds since they act as obstacles to flight and are used for perching and nesting, which can result in collisions or electrocutions. These interactions often endanger wildlife populations and may also result in high financial costs for companies. Flight behaviour plays a crucial role in collision risk, and the study of flight altitudes enables us to understand what drives birds to fly at collision risk altitudes. This allows the identification of high-risk areas, conditions and bird behaviours, and the implementation of mitigation measures by power line companies. In this study, we use boosted random tree modelling to identify drivers of white stork (Ciconia ciconia) flight altitudes and to investigate the factors that lead them to fly at collision risk alt...
Food waste disposal represents a major global source of predictable anthropogenic food subsidies ... more Food waste disposal represents a major global source of predictable anthropogenic food subsidies and is exploited by many organisms. However, the energetic cost-benefits of foraging on these food subsidies have remained largely unexplored. Here we investigate the year-round foraging decisions of resident white storks, Ciconia ciconia, in Iberia, and assess the energetic and time cost-benefits of foraging on both landfill waste and natural food sources. To do so, we use GPS and acceleration data from 55 individuals tagged in southern Portugal between 2016 and 2019. We find that the probability of attending landfill sites was 60% during the non-breeding season and 44% during the breeding season. Moreover, foraging on landfill waste is a time- and energy-saving strategy; although birds had to travel 20% further to exploit this resource during the breeding period, they spent overall 10% less energy than when foraging on natural prey. We show that this relationship could be mediated by a...
Animal movement is mainly determined by spatial and temporal changes in resource availability. Fo... more Animal movement is mainly determined by spatial and temporal changes in resource availability. For wetland specialists, the seasonal availability of surface water may be a major determinant of their movement patterns. This study is the first to examine the movements of Shoebills (Balaeniceps rex), an iconic and vulnerable bird species. Using GPS transmitters deployed on six immature and one adult Shoebills over a 5-year period, during which four immatures matured into adults, we analyse their home ranges and distances moved in the Bangweulu Wetlands, Zambia. We relate their movements at the start of the rainy season (October to December) to changes in Normalized Difference Water Index (NDWI), a proxy for surface water. We show that Shoebills stay in the Bangweulu Wetlands all year round, moving less than 3 km per day on 81% of days. However, average annual home ranges were large, with high individual variability, but were similar between age classes. Immature and adult Shoebills res...
Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet... more Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet, behavioural responses to these aspects of anthropogenically-modified forests remain poorly investigated. Here, we analyse the effects of small human-made clearings and secondary forests on tropical bats by examining the guild- and species-level activity patterns of phyllostomids sampled in the Central Amazon, Brazil. Specifically, we contrast the temporal activity patterns and degree of temporal overlap of six frugivorous and four gleaning animalivorous species in old-growth forest and second-growth forest and of four frugivores in old-growth forest and forest clearings. The activity patterns of frugivores and gleaning animalivores did not change between old-growth forest and second-growth, nor did the activity patterns of frugivores between old-growth forest and clearings. However, at the species level we detected significant differences for Artibeus obscurus (old-growth forest vs. se...
Alternative migratory strategies can coexist within animal populations and species. Anthropogenic... more Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade‐offs associated with four different movement strategies (long‐ and short‐distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long‐distance migration towards year‐round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with triaxial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity‐related energy expenditure. Additionally, we monitored nesting colonies to assess individ...
Background Migration phenology is shifting for many long-distance migrants due to global climate ... more Background Migration phenology is shifting for many long-distance migrants due to global climate change, however the timing and duration of migration may influence the environmental conditions individuals encounter, with potential fitness consequences. Species with asynchronous migrations, i.e., with variability in migration timing, provide an excellent opportunity to investigate how of the conditions individuals experience during migration can vary and affect the migratory performance, route, and destination of migrants. Methods Here, we use GPS tracking and accelerometer data to examine if timing of autumn migration influences the migratory performance (duration, distance, route straightness, energy expenditure) and migration destinations of a long-distance, asynchronous, migrant, the white stork (Ciconia ciconia). We also compare the weather conditions (wind speed, wind direction, and boundary layer height) encountered on migration and examine the influence of wind direction on s...
Anthropogenic structures are increasingly encroaching wildlife habitats, creating conflicts betwe... more Anthropogenic structures are increasingly encroaching wildlife habitats, creating conflicts between humans and animals. Scaling up renewable energy requires new infrastructures such as power lines, that cause high mortality among birds since they act as obstacles to flight and are used for perching and nesting, which can result in collisions or electrocutions. These interactions often endanger wildlife populations and may also result in high financial costs for companies. Flight behaviour plays a crucial role in collision risk, and the study of flight altitudes enables us to understand what drives birds to fly at collision risk altitudes. This allows the identification of high-risk areas, conditions and bird behaviours, and the implementation of mitigation measures by power line companies. In this study, we use boosted random tree modelling to identify drivers of white stork (Ciconia ciconia) flight altitudes and to investigate the factors that lead them to fly at collision risk alt...
Food waste disposal represents a major global source of predictable anthropogenic food subsidies ... more Food waste disposal represents a major global source of predictable anthropogenic food subsidies and is exploited by many organisms. However, the energetic cost-benefits of foraging on these food subsidies have remained largely unexplored. Here we investigate the year-round foraging decisions of resident white storks, Ciconia ciconia, in Iberia, and assess the energetic and time cost-benefits of foraging on both landfill waste and natural food sources. To do so, we use GPS and acceleration data from 55 individuals tagged in southern Portugal between 2016 and 2019. We find that the probability of attending landfill sites was 60% during the non-breeding season and 44% during the breeding season. Moreover, foraging on landfill waste is a time- and energy-saving strategy; although birds had to travel 20% further to exploit this resource during the breeding period, they spent overall 10% less energy than when foraging on natural prey. We show that this relationship could be mediated by a...
Animal movement is mainly determined by spatial and temporal changes in resource availability. Fo... more Animal movement is mainly determined by spatial and temporal changes in resource availability. For wetland specialists, the seasonal availability of surface water may be a major determinant of their movement patterns. This study is the first to examine the movements of Shoebills (Balaeniceps rex), an iconic and vulnerable bird species. Using GPS transmitters deployed on six immature and one adult Shoebills over a 5-year period, during which four immatures matured into adults, we analyse their home ranges and distances moved in the Bangweulu Wetlands, Zambia. We relate their movements at the start of the rainy season (October to December) to changes in Normalized Difference Water Index (NDWI), a proxy for surface water. We show that Shoebills stay in the Bangweulu Wetlands all year round, moving less than 3 km per day on 81% of days. However, average annual home ranges were large, with high individual variability, but were similar between age classes. Immature and adult Shoebills res...
Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet... more Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet, behavioural responses to these aspects of anthropogenically-modified forests remain poorly investigated. Here, we analyse the effects of small human-made clearings and secondary forests on tropical bats by examining the guild- and species-level activity patterns of phyllostomids sampled in the Central Amazon, Brazil. Specifically, we contrast the temporal activity patterns and degree of temporal overlap of six frugivorous and four gleaning animalivorous species in old-growth forest and second-growth forest and of four frugivores in old-growth forest and forest clearings. The activity patterns of frugivores and gleaning animalivores did not change between old-growth forest and second-growth, nor did the activity patterns of frugivores between old-growth forest and clearings. However, at the species level we detected significant differences for Artibeus obscurus (old-growth forest vs. se...
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