0000000000172398
AUTHOR
Clara García-ripollés
Interspecific comparison of the performance of soaring migrants in relation to morphology, meteorological conditions and migration strategies.
This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al.
Wind effects on the migration routes of trans-Saharan soaring raptors: geographical, seasonal, and interspecific variation
Wind is among the most important environmental factors shaping birds’ migration patterns. Birds must deal with the displacement caused by crosswinds and their behavior can vary according to different factors such as flight mode, migratory season, experience, and distance to goal areas. Here we analyze the relationship between wind and migratory movements of three raptor species which migrate by soaring–gliding flight: Egyptian vulture Neophron percnopterus, booted eagle Aquila pennata, and short-toed snake eagle Circaetus gallicus. We analyzed daily migratory segments (i.e., the path joining consecutive roosting locations) using data recorded by GPS satellite telemetry. Daily movements of E…
Large birds travel farther in homogeneous environments
Aim: Animal movement is an important determinant of individual survival, population dynamics and ecosystem structure and function. Nonetheless, it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside the migratory period, we examined how the distribution of resources affects the movement patterns of both large terrestrial birds (e.g., raptors, bustards and hornbills) and waterbirds (e.g., cranes, storks, ducks, geese and flamingos). Location: Global. Time period: 2003–2015. Major taxa studied: Birds. Methods: We compiled GPS tracking data for 386 individuals across 3…
Diurnal timing of nonmigratory movement by birds: the importance of foraging spatial scales
Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of timing of movement activity among species using six temporal variables: start of activity relative to sunrise, end of activity relative to sunset, relative speed at midday, number of movement bouts, bout duration and proportion of active daytime hours. We test for the influence of flight mode and foraging habitat on the timing of movement activit…
Spatial and Temporal Variability in Migration of a Soaring Raptor Across Three Continents
Disentangling individual- and population-level variation in migratory movements is necessary for understanding migration at the species level. However, very few studies have analyzed these patterns across large portions of species' distributions. We compiled a large telemetry dataset on the globally endangered egyptian vulture neophron percnopterus (94 individuals, 188 completed migratory journeys), tracked across similar to 70% of the species' global range, to analyze spatial and temporal variability of migratory movements within and among individuals and populations. We found high migratory connectivity at large spatial scales (i.e., different subpopulations showed little overlap in winte…
Individual repeatability in timing and spatial flexibility of migration routes of trans-Saharan migratory raptors
Satellite-tracking technology has allowed scientists to make a quantum leap in the field of migration ecology. Nowadays, the basic description of migratory routes of many species of birds has been reported. However, the investigation of bird migration at individual level (i.e. repeatability in migratory routes and timing) still remains seldom explored. Here, we investigated repeated migratory trips of a trans-Saharan endangered migratory raptor, the Egyptian Vulture Neophron percnopterus, tracked by GPS satellite telemetry. We compared between- and within-individual variation in migratory routes and timing in order to assess the degree of repeatability (or conversely, the flexibility) in mi…
Food predictability determines space use of endangered vultures: implications for management of supplementary feeding.
Understanding space use of free-living endangered animals is key to inform management decisions for conservation planning. Like most scavengers, vultures have evolved under a context of unpredictability of food resources (i.e. exploiting scattered carcasses that are intermittently available). However, the role of predictable sources of food in shaping spatial ecology of vultures has seldom been studied in detail. Here, we quantify the home range of the Egyptian vulture (Neophron percnopterus), a long-lived raptor which has experienced severe population decline throughout its range and is qualified as endangered worldwide. To this end six adults were tracked by satellite telemetry in Spain d…
Geographical assemblages of European raptors and owls
Abstract In this work we look for geographical structure patterns in European raptors (Order: Falconiformes) and owls (Order: Strigiformes). For this purpose we have conducted our research using freely available tools such as statistical software and databases. To perform the study, presence–absence data for the European raptors and owl species (Class Aves) were downloaded from the BirdLife International website. Using the freely available “pvclust” R-package, we applied similarity Jaccard index and cluster analysis in order to delineate biogeographical relationships for European countries. According to the cluster of similarity, we found that Europe is structured into two main geographical…
A Case of Predation of a Eurasian Eagle-Owl by a Bonelli's Eagle
Although some of these hypotheses are not mutually exclusive, in light of our field observations and experience with both species in the study area, we would favor the first hypothesis as food availability is low in our study area (P. López-López, C. García-Ripollés, J. Giménez, and V. Urios unpubl. data). The second and third hypotheses could also account for this behavior, especially considering previous events of nestling Bonelli's Eagles being killed by eagle-owls (Real and Manosa 1990). Notwithstanding, if the''predatorremoval hypothesis'' were true, the frequency of lethal interactions among both species would be probably much higher and thus previously reported in the literature. Unf…
Differential survival throughout the full annual cycle of a migratory bird presents a life‐history trade‐off
1. Long‐distance migrations are among the most physically demanding feats animals perform. Understanding the potential costs and benefits of such behaviour is a fundamental question in ecology and evolution. A hypothetical cost of migration should be outweighed by higher productivity and/or higher annual survival, but few studies on migratory species have been able to directly quantify patterns of survival throughout the full annual cycle and across the majority of a species’ range. 2. Here, we use telemetry data from 220 migratory Egyptian vultures Neophron percnopterus, tracked for 3,186 bird months and across approximately 70% of the species’ global distribution, to test for differences …
Scavengers on the move: behavioural changes in foraging search patterns during the annual cycle
Background: Optimal foraging theory predicts that animals will tend to maximize foraging success by optimizing search strategies. However, how organisms detect sparsely distributed food resources remains an open question. When targets are sparse and unpredictably distributed, a Lévy strategy should maximize foraging success. By contrast, when resources are abundant and regularly distributed, simple Brownian random movement should be sufficient. Although very different groups of organisms exhibit Lévy motion, the shift from a Lévy to a Brownian search strategy has been suggested to depend on internal and external factors such as sex, prey density, or environmental context. However, animal re…
First description of migration and wintering of adult Egyptian Vultures Neophron percnopterus tracked by GPS satellite telemetry
Capsule Over two years birds showed high territorial and high winter site fidelity in the Sahel.
Data from: Large birds travel farther in homogeneous environments
Aim: Animal movement is an important determinant of individual survival, population dynamics, and ecosystem structure and function. Yet it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside of the migratory period, we examined how the distribution of resources affect the movement patterns of both large terrestrial birds (e.g., raptors, bustards, hornbills) and waterbirds (e.g., cranes, storks, ducks, geese, flamingos). Location: Global Time Period: 2003 - 2015 Major taxa studied: Birds Methods: We compiled GPS tracking data for 386 individuals across 36 bird specie…
Appendix B. Correlation test between measures of home range size, spatial parameters, and the number of relocations obtained per individual; LMM for the standardized RUF coefficients; and model validation graphs for the LMMs of the home range area.
Correlation test between measures of home range size, spatial parameters, and the number of relocations obtained per individual; LMM for the standardized RUF coefficients; and model validation graphs for the LMMs of the home range area.
Appendix A. Computation of two- and three-dimensional overlap in home ranges.
Computation of two- and three-dimensional overlap in home ranges.