Pascual López-López

Weather conditions promote route flexibility during open ocean crossing in a long-distance migratory raptor

Weather conditions are paramount in shaping birds’ migratory routes, promoting the evolution of behavioural plasticity and allowing for adaptive decisions on when to depart or stop during migration. Here, we describe and analyze the influence of weather conditions in shaping the sea-crossing stage of the pre-breeding journey made by a long-distance migratory bird, the Eleonora’s falcon (Falco eleonorae), tracked by satellite telemetry from the wintering grounds in the Southern Hemisphere to the breeding sites in the Northern Hemisphere. As far as we know, the data presented here are the first report of repeated oceanic journeys of the same individuals in consecutive years. Our results show inter-annual variability in the routes followed by Eleonora’s falcons when crossing the Strait of Mozambique, between Madagascar and eastern continental Africa. Interestingly, our observations illustrate that individuals show high behavioural plasticity and are able to change their migration route from one year to another in response to weather conditions, thus minimising the risk of long ocean crossing by selecting winds blowing towards Africa for departure and changing the routes to avoid low pressure areas en route. Our results suggest that weather conditions can really act as obstacles during migration, and thus, besides ecological barriers, the migratory behaviour of birds could also be shaped by “meteorological barriers”. We briefly discuss orientation mechanisms used for navigation. Since environmental conditions during migration could cause carry-over effects, we consider that forecasting how global changes of weather patterns will shape the behaviour of migratory birds is of the utmost importance.

Interspecific comparison of the performance of soaring migrants in relation to morphology, meteorological conditions and migration strategies

Background Performance of migrating birds can be affected by a number of intrinsic and extrinsic factors like morphology, meteorological conditions and migration strategies. We compared travel speeds of four raptor species during their crossing of the Sahara desert. Focusing the analyses on this region allows us to compare different species under equivalent conditions in order to disentangle which factors affect migratory performance. Methodology/Principal Finding We tracked raptors using GPS satellite transmitters from Sweden, Spain and Italy, and evaluated their migratory performance at both an hourly and a daily scale. Hourly data (flight speed and altitude for intervals of two hours) were analyzed in relation to time of day, species and season, and daily data (distance between roosting sites) in relation to species, season, day length and tailwind support. Conclusions/Significance Despite a clear variation in morphology, interspecific differences were generally very small, and did only arise in spring, with long-distance migrants (>5000 km: osprey and Western marsh-harrier) being faster than species that migrate shorter distances (Egyptian vulture and short-toed eagle). Our results suggest that the most important factor explaining hourly variation in flight speed is time of day, while at a daily scale, tailwind support is the most important factor explaining variation in daily distance, raising new questions about the consequences of possible future changes in worldwide wind patterns.

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 informing 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 that 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 during the breeding season, from 2007 to 2012, recording 10360 GPS locations. Using Resource Utilization Functions, we assessed the topology of the Utilization Distribution, a three-dimensional measure that shows the probability of finding an animal within the home range. Our results showed how food availability, and principally, how food predictability, determines ranging behavior of this species. Egyptian Vultures showed consistent site fidelity across years, measured as the two- and three-dimensional overlap in their home ranges. Space use varied considerably within the home range and remarkably, places located far from nesting sites were used more frequently than some areas located closer. Therefore, traditional conservation measures based on establishing restrictive rules within a fixed radius around nesting sites could be biologically meaningless if other areas within the home range are not protected too. Finally, our results emphasize the importance of anthropogenic predictable sources of food (mainly vulture restaurants) in shaping the space use of scavengers, which is in agreement with recent findings. Hence, measures aimed at ensuring food availability are essential to preserve this endangered vulture, especially in the present context of limiting carrion dumping in the field due to sanitary regulations according to European legislation.

Solving Man-Induced Large-Scale Conservation Problems: The Spanish Imperial Eagle and Power Lines

Background Man-induced mortality of birds caused by electrocution with poorly-designed pylons and power lines has been reported to be an important mortality factor that could become a major cause of population decline of one of the world rarest raptors, the Spanish imperial eagle (Aquila adalberti). Consequently it has resulted in an increasing awareness of this problem amongst land managers and the public at large, as well as increased research into the distribution of electrocution events and likely mitigation measures. Methodology/Principal Findings We provide information of how mitigation measures implemented on a regional level under the conservation program of the Spanish imperial eagle have resulted in a positive shift of demographic trends in Spain. A 35 years temporal data set (1974–2009) on mortality of Spanish imperial eagle was recorded, including population censuses, and data on electrocution and non-electrocution of birds. Additional information was obtained from 32 radio-tracked young eagles and specific field surveys. Data were divided into two periods, before and after the approval of a regional regulation of power line design in 1990 which established mandatory rules aimed at minimizing or eliminating the negative impacts of power lines facilities on avian populations. Our results show how population size and the average annual percentage of population change have increased between the two periods, whereas the number of electrocuted birds has been reduced in spite of the continuous growing of the wiring network. Conclusions Our results demonstrate that solving bird electrocution is an affordable problem if political interest is shown and financial investment is made. The combination of an adequate spatial planning with a sustainable development of human infrastructures will contribute positively to the conservation of the Spanish imperial eagle and may underpin population growth and range expansion, with positive side effects on other endangered species.

Satellite telemetry reveals individual variation in juvenile Bonelli’s eagle dispersal areas

Natal dispersal is the time elapsed between departing from the natal site and settling to attempt breeding for the first time. In long-lived species with deferred sexual maturity this period may last several years, making this process crucial for their survival and conservation. Here we present a large-scale outline of juvenile Bonelli’s eagle’s dispersal areas in the Iberian Peninsula. We describe the ranging and movement patterns of 14 juvenile Bonelli’s eagles during their dispersal period, studied by satellite telemetry. Three distinct phases during the juveniles’ first year of life were detected, namely, the dependence period, the departure from the parental territory, and the settlement in dispersal areas. In general, between-sex differences in relation to ranging behavior were not significant. Interestingly, there seems not to be a few, clearly delimited, overlapping Bonelli’s eagle’s juvenile dispersal areas within the Iberian Peninsula. A total of 17 dispersal areas were detected, with some animals using more than one. These areas were located in eight autonomous communities (Spanish administrative units), being the most important Castilla-La Mancha and Andalucía. Juveniles were more frequently located in cultivated man-managed areas, with non-irrigated herbaceous crops. This is probably due to higher prey availability and higher efficiency in prey capture in these open areas, as well as to the absence of breeding pairs. This has important management implications, suggesting that conservation efforts should focus on the whole landscape matrix of man-managed ecosystems rather than in a few clearly delimited geographic areas.

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.

Ranging behaviour of non-breeding Eurasian Griffon Vultures Gyps fulvus: a GPS-telemetry study

Abstract. Little is known about the spatial ecology and ranging behaviour of vultures in Europe. In this paper we used GPS satellite telemetry to assess home-ranges of eight non-breeding Eurasian Griffon Vultures in Spain, trying to answer the main questions on when (i.e. the time of the day), how far (i.e. hourly and daily distances) and where vultures range (i.e. home-range size). Results indicated that vultures ranged extensively mainly in areas where traditional stock-raising practices and pasturing were still common, also including some vulture restaurants, which were visited occasionally. Eurasian Griffon Vultures concentrated their hourly and daily movements in the middle of the day, when the availability of thermal updrafts was higher, favouring foraging activities. The overall foraging range, calculated as Minimum Convex Polygon (MCP) (7419 km2), or as 95% and 50% kernel contours (4078 km2 and 489 km2, respectively), was higher than those reported in previous studies. The precise knowledge of the ranging behaviour and spatial parameters is particularly important for the conservation of scavenger species inhabiting human-dominated areas where human activities may jeopardize vulture populations in the long term.

Integrating effects of supplementary feeding, poisoning, pollutant ingestion and wind farms of two vulture species in Spain using a population viability analysis

Population viability analyses (PVAs) are a useful technique in risk-assessment studies aimed at determining which demographic parameters are most influential in population persistence. Here, we incorporate demographic and environmental stochasticity in the construction of individual-based models integrating the effects of different scenarios in a PVA of the Eurasian Griffon Vulture (Gyps fulvus) and the endangered Egyptian Vulture (Neophron percnopterus) in Spain. Scenarios were based on reasonable options of population management, including effects of supplementary feeding (decreasing mortality and increasing fecundity), extensive wind farm development (increasing mortality), and catastrophic events such as poisoning (decreasing fecundity and survival) or pollutant ingestion (decreasing fecundity but no effect on survival). Our results show that those measures affecting survival show higher negative effects on population growth rate than those affecting fecundity. The outcomes were different and highly depend on the initial conditions and the species considered, with stronger negative effects on Egyptian Vulture populations. For both species, under similar conditions, the effects of massive poisoning, even occurring at low time frequency, had stronger negative consequences in population trends than the pollutant accumulation, or other actions affecting survival, such as installation of wind farms. Measures aimed at improving survival and fecundity such as supplementary feeding at vulture restaurants give rise to positive population trends. The establishment of management actions aimed at improving the birds’ survival and increasing breeding success will probably boost the scavengers’ populations into an upward trend, which is particularly important in the case of the endangered Egyptian Vulture.ZusammenfassungPopulation Viability Analysis (PVA) ist eine nützliche Methode in Risikobewertungsstudien, die darauf abzielt, zu ermitteln, welche demographischen Parameter für das Fortbestehen von Populationen am einflussreichsten sind. Hier berücksichtigen wir demographische Stochastizität und Umweltstochastizität bei der Konstruktion individuenbasierter Modelle, welche die Effekte verschiedener Szenarien in eine PVA für den Gänsegeier (Gyps fulvus) und den stark gefährdeten Schmutzgeier (Neophron percnopterus) in Spanien integrieren. Die Szenarien beruhen auf angemessenen Optionen von Populationsmanagement, welche die Effekte von Zufüttern (erniedrigt die Mortalität und erhöht die Fruchtbarkeit), großflächigem Bau von Windenergieparks (erhöht die Mortalität) und katastrophalen Ereignissen wie Vergiftung (erniedrigt die Fruchtbarkeit und das Überleben) oder Schadstoffaufnahme (erniedrigt die Fruchtbarkeit, aber hat keinen Effekt auf das Überleben) einschließen. Unsere Ergebnisse zeigen, dass diejenigen Maße, die das Überleben beeinflussen, stärkere negative Effekte auf die Wachstumsrate der Population haben als die, welche die Fruchtbarkeit beeinflussen. Die Folgen waren unterschiedlich und hängen stark von den anfänglichen Bedingungen und der betrachteten Art ab, wobei die negativen Effekte auf die Schmutzgeierpopulationen stärker waren. Für beide Arten hatten unter ähnlichen Bedingungen die Effekte schwerer Vergiftung stärkere negative Folgen für die Populationsentwicklung als die Anreicherung von Schadstoffen oder andere Maßnahmen, die das Überleben betrafen, wie die Errichtung von Windenergieparks, und das obwohl Vergiftungen selten auftraten. Maßnahmen, die darauf abzielen, das Überleben und die Fruchtbarkeit zu verbessern, wie das Zufüttern in „Geierrestaurants”, führen zu positiven Populationsentwicklungen. Die Etablierung von Managementmaßnahmen, die anstreben, das Überleben und den Bruterfolg der Vögel zu verbessern, wird die positive Populationsentwicklung dieser Aasfresser wahrscheinlich fördern, was besonders im Falle des stark gefährdeten Schmutzgeiers wichtig ist.

Are important bird areas and special protected areas enough for conservation?: the case of Bonelli’s eagle in a Mediterranean area

The Bonelli’s eagle (BE) is considered by the European Union as a high-priority species for conservation in the Valencian Community (East of Spain). However, in 2006 the European Union opened a legal procedure against the Spanish Kingdom, accused of lacking of an adequate network of special protected areas (SPAs) to preserve the BE in the region. Here we evaluate whether important bird areas (IBAs) and SPAs network is enough to preserve this species, on the basis of a thorough analysis of habitat preferences. A GAP analysis is performed to conduct a revision of current SPAs and BirdLife proposed IBAs. Our results suggest that the current network of SPAs becomes insufficient to protect the BE. The IBAs network, although improves the current network of SPAs, increasing the percentage of BE potential habitat included, also results inadequate. We propose a new SPAs network according to the potential suitable habitat for the species. Given the trade-off between financial investment and the conservation of biodiversity, we propose to maximize the surface of potential habitat included in the protected network minimizing the surface of the region that would be necessary to protect, thus avoiding an unnecessary expense and otherwise unrealistic results.

Wintering habitats of Eleonora's Falcons Falco eleonorae in Madagascar

Capsule Eleonoras Falcons wintering in Madagascar selected degraded humid forests and cultivated areas close to pristine humid forest. Aims To identify the habitat preferences of Eleonoras 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 Eleonoras 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. Results The analyses showed a preference for degraded humid forests and cultivated lands within areas where pristine humid forests were the most abundant habitat type. Conclusions Eleonoras Falcons could be taking advantage from a spill-over edge effect of their insect prey into cultivated and more open areas close to humid forests. However, the importance of humid forests for Eleonoras Falcons seems to be high. The current loss of this habitat in Madagascar is a cause for concern with respect to the conservation of this long-distance migratory falcon species.