0000000001312843
AUTHOR
Vicente Urios
Ecological specialization to fluctuating resources prevents long-distance migratory raptors from becoming sedentary on islands
[Background]: The adaptive transition between behavioral strategies, such as the shift from migratoriness to sedentariness, remains an outstanding question in evolutionary ecology. Density-dependent variation in the age of first breeding has been proposed as a feasible mechanism through which long-lived migratory birds with deferred sexual maturity should become sedentary to persist on islands. Although this pattern seems to hold for most raptors and herons, a few exceptions have been identified. One of these exceptions is the Eleonora's falcon, a long-distance migratory bird, which shows one of the most peculiar adaptations in the timing of reproduction and food requirements among raptors.…
Spatial ecology and habitat use of adult Booted eagles (Aquila pennata) during the breeding season: implications for conservation.
Fast-moving technological advances, such as satellite tracking technologies, are providing in-depth information of aspects of avian ecology hitherto unknown. In fact, detailed information about movement ecology and ranging behaviour of birds is important not only from the perspective of the basic ecology, but also from the conservation point of view. This is particularly important in European countries where agricultural intensification, land abandonment and the withdrawal of traditional management agro-forestry practices pose a threat to biodiversity. The Booted Eagle, likewise other forest raptors, is an adequate bioindicator of human-dominated agro-forestry Mediterranean landscapes in wh…
Pre-Migratory Movements of Adult Montagu's HarriersCircus pygargus
Pre-migratory and migratory movements of Montagu's Harrier Circus pygargus, a long-distance migrant, are poorly documented by ring recoveries and observations. In the present study, we tagged 10 adult Montagu's Harriers in NE Spain with satellite transmitters and tracked their movements until their arrival on the wintering grounds. To identify the end of the breeding season and the onset of the migration based on our satellite-telemetry data we developed and applied a statistical approach, defining the time period between these two events as the pre-migratory stage. We then compared habitat preferences during the breeding season and the pre-migratory stage. The duration of the pre-migratory…
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…
Use of digital trail cameras to study Bonelli's eagle diet during the nestling period
Abstract The study of avian diet is one of the most commonly discussed topics in Ornithology. Different methods such as direct observations of hunting, analysis of pellets and collection of prey remains have usually been employed to study avian diet. Fortunately, digital technologies have rapidly advanced in recent years, allowing researchers to increase our understanding of avian behaviour. Here we report the outcomes of a pilot project to study the diet of Bonelli's eagle (Aquila fasciata, Syn = Hieraaetus fasciatus) during the nestling period using digital trail cameras. We describe the monitoring system, provide results on dietary composition and discuss advantages and shortcomings of t…
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…
Holidays? Not for all. Eagles have larger home ranges on holidays as a consequence of human disturbance
Human-wildlife conflicts are the object of raising concern in conservation biology. People living in urban areas are rapidly increasing worldwide and consequently the temporal pattern of occupation of natural areas for recreation is changing as well, resulting in an ever-increasing concentration of people during weekends and holidays. This is particularly evident in affluent societies, where more recreationists visit natural areas on holidays and weekends, causing disturbance to wildlife in the so-called “weekend effect”. Here, we tested the response to disturbance of 30 Bonelli's eagles tracked by high-frequency GPS/GSM telemetry. We analysed daily home-range size, a measure of changing be…
Wintering habitats of Eleonora's FalconsFalco eleonoraein Madagascar
[Capsule]: Eleonora's Falcons wintering in Madagascar selected degraded humid forests and cultivated areas close to pristine humid forest. [Aims]: To identify the habitat preferences of Eleonora's Falcon Falco eleonorae on their wintering grounds in Madagascar, and to use this information to gain insights into the conservation priorities of this species. [Methods]: A total of 11 Eleonora's Falcons were captured in Spain in 2007 and 2008 and equipped with solar-powered satellite transmitters. We obtained information on five complete wintering events for three birds, two of them tracked for two consecutive years. Data were analyzed using geographic information system-based cartography. [Resul…
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…
Regional and age-dependent differences in the effect of wind on the migratory routes of Eleonora's Falcon.
During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecological barriers and visibility of landmarks. We analysed the effect of wind (tailwinds and crosswinds) on daily movement rates (forward and perpendicular) of Eleonora’s falcons using ARGOS satellite telemetry, during their trans-continental autumn migration to Madagascar, in relation to the different crossed regions and individuals’ age class. Our results showed that the effect of wind on daily movement rates was not uniform, being stronger in the farthest region from the migration goal, the Sahara desert, with adults being more affected than juveniles in this region. In the Sah…
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 …
Tri-axial accelerometry shows differences in energy expenditure and parental effort throughout the breeding season in long-lived raptors
Cutting-edge technologies are extremely useful to develop new workflows in studying ecological data, particularly to understand animal behavior and movement trajectories at the individual level. Although parental care is a well-studied phenomenon, most studies have been focused on direct observational or video recording data, as well as experimental manipulation. Therefore, what happens out of our sight still remains unknown. Using high-frequency GPS/GSM dataloggers and tri-axial accelerometers we monitored 25 Bonelli’s eagles Aquila fasciata during the breeding season to understand parental activities from a broader perspective. We used recursive data, measured as number of visits and resi…
Estimating the onset of dispersal in endangered Bonelli's Eagles Hieraaetus fasciatus tracked by satellite telemetry: a comparison between methods
This project was funded by the Terra Natura Foundation. L.C. and P.L.-L. are supported by FPU grants of the Spanish Ministerio de Educacion y Ciencia (references AP2001-1444 and AP2005-0874, respectively).
Coprology of Panthera tigris altaica and Felis bengalensis euptilurus from the Russian Far East
Fecal samples from the Siberian tiger (Panthera tigris altaica) and the Amur cat (Felis bengalensis euptilurus) from Far Eastern Russia, were examined for parasites. A natural sedimentation methodology was used and a complete examination of all the sediment was performed. This fecal investigation allowed us to isolate and identify several developmental stages of gastrointestinal, hepatic, and respiratory parasites. Five parasites were found from P. t. altaica: 11 trematodes (Platynosomum fastosum) and 4 nematodes (Strongyloides sp., Ancylostomatidae, Toxascaris leonina, and Toxocara cati). Five parasites were found from F. b. euptilurus: 1 cestode (Diplopylidium sp.) and 4 nematodes (Trichu…
The First Case of Successful Breeding of a Golden EagleAquila chrysaetosTracked from Birth by Satellite Telemetry
The natal dispersal of a Golden Eagle from its natal eyrie to the site where it reproduced for the first time was monitored. After covering > 16 000 km2 in its three years of juvenile dispersal, and despite flying > 130 km from its natal site, the eagle finally settled in a vacant territory just 26 km away from the place where it had hatched. Almost 95% of the total dispersal area was visited for the first time during the first year of tracking; less than 40% of the disper- sal area was used during the remainder of the dispersal period. During dispersal the eagle regularly visited territories occupied by adult Golden Eagles. Previous records of the occupancy of the territory the eagle curre…
Natal dispersal and recruitment of two Bonelli's Eagles <I>Aquila fasciata</I>: a four-year satellite tracking study
To study natal dispersal and recruitment to the breeding population in Bonelli's Eagle, two nestlings were tagged with satellite transmitters in the Iberian Peninsula in 2002. Their monthly ranges and distances were computed and fitted to regression models to describe their general trend. One bird, a female, dispersed and settled rapidly in an area which she explored intensively during four years and which finally became her first breeding site. The natal dis- persal distance was 441 km, and the bird cannot therefore be considered philopatric. The other bird, a male, alternated between long travelling episodes and settlement in particular areas, exploring different regions both distant from…
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…
Broad-front migration leads to strong migratory connectivity in the lesser kestrel (Falco naumanni)
Aim: Migratory animals regularly move between often distant breeding and non‐breeding ranges. Knowledge about how these ranges are linked by movements of individuals from different populations is crucial for unravelling temporal variability in population spatial structuring and for identifying environmental drivers of population dynamics acting at different spatio‐temporal scales. We performed a large‐scale individual‐based migration tracking study of an Afro‐Palaearctic migratory raptor, to determine the patterns of migratory connectivity of European breeding populations. Location: Europe, Africa. Methods: Migration data were recorded using different devices (geolocators, satellite transmi…
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.
Incorporating spatial structure and stochasticity in endangered Bonelli’s eagle’s population models: implications for conservation and management
Population models have played a chief role informing management decisions for the endangered Bonelli’s eagle (Aquila fasciata) in Spain. In this paper, we incorporate spatial structure and stochasticity in the construction of individual-based metapopulation models, and use these models to explore the effects of possible management actions on the persistence of the species in Spain. To build the models we used data on seven sub-populations that have experienced different trends in the last decades, and we introduced new estimates of pre-adult survival rate. The elasticity analysis of our models showed that when the interchange of individuals among sub-populations is taken into account, pre-a…
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.