Eva Casado

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.

Plasma chemistry in booted eagle (Hieraaetus pennatus) during breeding season.

Most studies that have examined raptor plasma chemistry have been conducted on birds living in captivity. In this study, we describe typical plasma chemistry values indicators of body condition in free-living Booted Eagles, Hieraaetus pennatus, from Doñana National Park (Spain). Values are compared with those of other raptors. Mean concentrations of creatinine, uric acid and urea were lower in adults than in nestlings, while glucose, DAT and AAT were lower in nestlings than in adults. Interactions of age/sex affected plasma mean levels of creatine kinase, glucose, AAT, uric acid and urea. Adult females showed significantly lower levels of creatine kinase, uric acid and urea than adult males and nestlings. Adult males had significantly higher levels of AAT than the other groups. The lowest levels of glucose and the highest levels of uric acid were found in nestling females. We think the differences in blood parameters can be explained by differences in size of species, of individuals (because of both body condition and sexual dimorphism) and diet.

Why birds with deferred sexual maturity are sedentary on islands: a systematic review.

Background Island faunas have played central roles in the development of evolutionary biology and ecology. Birds are among the most studied organisms on islands, in part because of their dispersal powers linked to migration. Even so, we lack of information about differences in the movement ecology of island versus mainland populations of birds. Methodology/Principal Findings Here we present a new general pattern indicating that large birds with deferred sexual maturity are sedentary on islands, and that they become so even when they are migratory on the mainland. Density-dependent variation in the age at first breeding affects the survivorship of insular populations and this, in turn, affects the movement ecology of large birds. Because density-dependent variation in the age of first breeding is critical to the long-term survival of small isolated populations of long-lived species, migratory forms can successfully colonize islands only if they become sedentary once there. Analyses of the movement ecology of continental and insular populations of 314 species of raptors, 113 species of Ciconiiformes and 136 species of passerines, along with individual-based population simulations confirm this prediction. Conclusions This finding has several consequences for speciation, colonization and survival of small isolated population of species with deferred sexual maturity.

Settlement and Successful Breeding of Reintroduced Spanish Imperial Eagles Aquila adalberti in the Province of Cadiz (Spain)

Summary. A project to reintroduce the Spanish imperial eagle in the province of Cadiz (Andalusia, Spain) began in 2002. The aim was to restore the former breeding nucleus, to encourage subpopulation interconnection and to ensure the long-term persistence of the southern metapopulation of this endemic Iberian species. A population reinforcement programme also began in 2005 at a location in the Doñana area (Andalusia, Spain) to improve the viability of this endangered subpopulation. Between 2002 and 2010, a total of 73 young Spanish imperial eagles were released at four locations by means of hacking. As a result, in 2010 a released male bred successfully with a non-reintroduced female and two young were reared. This was the first successful breeding event recorded in Cadiz province since 1960. An additional territorial pair also settled in the release area in 2010 and four more translocated individuals have made breeding attempts within nearby breeding subpopulations since 2006. The settlement and breeding of reintroduced individuals is the starting point of a future population and constitutes a relevant indicator for the evaluation of the project.

FIRST BREEDING SUCCESS OF OSPREY (PANDION HALIAETUS) IN MAINLAND SPAIN SINCE 1981 USING CROSS-FOSTERING

The current status of European populations of Osprey (Pandion haliaetus) is clearly different among regions (Saurola 1997, J. Raptor Res. 31:129–137). Although the central and northern areas of Europe support large populations in favorable conditions with increasing or stabilized trends, the situation in the Mediterranean basin is unfavorable, with few, small and isolated populations (Thibault et al. 2001, Le Balbuzard pêcheur en Corse: du martyre au symbole de la protection de la nature, Ed. Alam, Ajaccio, France). In Spain there are only two small breeding populations, each consisting of about 15–20 pairs, both in insular territories: the Canary Islands and Balearic Islands (Martı́ and Moral 2003, Atlas de las aves reproductoras de España, Ministerio de Medio Ambiente, SEO/BirdLife, Madrid, Spain). The species was extirpated from mainland Spain after 1981, when the last pair bred in the province of Alicante (Urios et al. 1991, Atlas de las aves nidificantes de la Comunidad Valenciana, Generalitat Valenciana, Valencia, Spain), after a continuous decline in the number of breeding pairs since the 1960s. The Iberian Peninsula is an important passage area for migratory Ospreys traveling between Europe and wintering grounds in Africa, and a small number of northern European birds winter in southern Spain (Saurola 1997). Despite apparently suitable breeding conditions (Casado 2005, J. Raptor Res. 39:168–173), Ospreys have been unable to recolonize the region, perhaps due to natal philopatry and low breeding dispersal (Poole 1989, Ospreys: a natural and unnatural history, Cambridge Univ. Press, Cambridge, U.K.). To accelerate the return of the Osprey to the Iberian Peninsula, a reintroduction program commenced in 2003 in the region of Andalusia (Casado 2005). Between 2003 and 2005, 42 young Ospreys were released, by means of hacking, at two locations: a reservoir in the province of Cádiz and a coastal marshland in the province of Huelva. In 2005, after 2 yr of releasing juveniles and observing interactions between adults and released young, we recorded three nest construction attempts by different non-reintroduced Osprey pairs close to the hacking site in Cádiz. All attempts were less than 40 km from the release point and one was only 2 km away, in the same reservoir. Only one of these three pairs constructed a complete nest and made a breeding attempt, at a reservoir 30 km from the nearest release point. The nest was built on top of an inactive power pole situated over the water near the shore. After a courtship period, from February to early March, the pair started to incubate on 16 March, but 2 d later a strong wind dislodged the nest. The pair stayed one more day at the power pole, but stopped incubating. Failed breeding attempts may reduce site or mate fidelity in subsequent breeding seasons (Newton 1979, Population ecology of raptors, Buteo Books, Vermillion, SD U.S.A.). Thus, to encourage site fidelity, we erected an artificial nest on another pylon 150 m away from the original nest 2 d after incubation stopped. The pair occupied the new platform the next day, showing pre-laying behavior until 29 March, when they began incubating a single egg. This egg was sterile or addled, because it had not hatched after more than 60 d of incubation, which was .15 d more than the maximum documented incubation period for Osprey (mean 5 39 d, range 35–43 d, Poole 1989). Because our objective was to encourage successful breeding behavior by the pair, and because we knew definitively that the natural attempt had failed, we decided to translocate two Osprey chicks from a demographically secure population to be fostered by the pair before this breeding attempt was definitively abandoned. Before proceeding, we had to ensure that the pair would be good foster parents, as they probably had no prior breeding experience. Also, collection and transportation of the young from the donor country would take several days. Consequently, we decided to use temporary cross-fostering by placing a chick of another non-endangered species in the nest. Cross-fostering is a manipulative technique that has been employed in many bird species including several birds of prey (Bird et al. 1985, International Council for Bird Preservation, Technical Publication No. 5:433–438; Cade and Temple 1994, Ibis 137:161–172). Although not recommended as a primary method in management programs for species recovery because of potentially contradictory results (Slagsvold et al. 2002, Proc. R. Soc. Lond. 269:1449–1455), cross-fostering has proved to be a useful supplementary technique in both long term and temporary situations (Bird et al. 1985; Barclay 1987 in B.G. Pendleton et al. [EDS.], Raptor management techniques manual, Natl. Wildl. Fed., Washington, DC U.S.A.). In this case, the selected cross-fostered species was the Black Kite (Milvus migrans) which is abundant in the area, is similar in

Morphometric sex determination of young Ospreys Pandion haliaetus using discriminant analysis

Capsule Discriminant functions based on morphometric variables provide a reliable method for sex identification of free‐living and hacked young Ospreys. Aims To describe an easy, accurate and low‐cost method for sex determination of fully grown nestling and fledgling Ospreys Pandion haliaetus based on morphometric measurements. Methods Four different measurements were taken in 114 birds (40–73 days old) and a DNA analysis, using PCR amplification, was carried out for sex identification. A forward stepwise discriminant analysis was performed to build the best explanatory discriminant models, which were subsequently validated using statistics and external samples. Results Our best discriminant function retained forearm and tarsus as the best predictor variables and classified 95.1% of the sample correctly, supported also by external cross‐validations with both hacked and free‐living birds. Moreover, a discriminant function with only forearm as predictor showed a similar high correct classification power (93.4%). Conclusions These discriminant functions can be used as a reliable and immediate method for sex determination of young Ospreys since they showed high discriminant accuracy, close to that of molecular procedures, and were supported by external cross‐validations, both for free‐living and hacked birds. Thus, these morphometric measurements should be considered as standard tools for future scientific studies and management of Osprey populations

Heat loss and site-dependent fecundity in chinstrap penguins (Pygoscelis antarctica)

We study the effects of heat loss and nest site quality on fecundity in a chinstrap penguin (Pygoscelis antarctica) colony on Deception Island, Antarctica. During the austral summers of 1990–1991, 1993–1994, and 1995–1996, 441 randomly selected nests were analyzed. Penguins breeding in the center of subcolonies hatched significantly earlier and had larger broods and than those nesting near or at the edge of the subcolonies. These differences, however, were significantly affected by interaction between year and nest location, being highly significant in colder years, when peripheral nests produce fewer young. Analysis of the rate of heat loss showed that penguins breeding at the edge of subcolonies lost heat twice as rapidly as those breeding in the interior of the subcolony. In a re-occupation experiment, evacuated center nests were re-occupied almost ten times as rapidly as edge nests. An analysis of mean fecundity in the period 1991–1996 and mean wind chill suggested that most of the variability in fecundity among years was related to differences in the rate of heat loss. Subcolonies tend to be as circular as possible, thereby decreasing the proportion of edge nests as the size of subcolony increases. Our results support the site-dependent fecundity hypothesis.

The role of density-dependence regulation in the misleading effect of the Aznalcollar mining spill on the booted eagle fecundity

The aim of this study was to assess the exposure and potential effects of the toxic elements released by the Aznalcollar spillage on the fecundity of the booted eagle (Hieraetus pennatus) population of Doñana National Park. We measured As, Cd, Cu, Pb, Zn, Sb and Tl levels in the blood of 24 individuals after the accident and also used data of reproductive performance of the species from 1976 to 2000. While As, Sb and Tl were below their detection limits and only 3 samples were above detection limit for Cd (0.02-0.04μg/dl), mean levels of Cu, Zn and Pb (μg/dl) were found to be 38.736, 532.937 and 0.719, respectively, in fledglings; and 66.112, 652.571 and 1.825, respectively, in adults. These levels were higher in adults, but they did not differ significantly between age classes and were at safe levels. In addition, a positive relationship between relative fecundity and the combination of Cu, Zn and Pb was observed. Following the mining spill, the mean population fecundity was lower (0.536 fledglings per pair in the population) than before (1.093). However, the decrease in fecundity over time was also related to the increase of breeding pairs, suggesting a density-dependent regulation and nullifying the mining spillage effect. Thus, although raptors have proved to be highly valuable biomonitors of environmental pollution, we must be especially cautious and go beyond the apparent effects that sometimes we quickly believe to detect, leading us to reach mistaken conclusions that could affect our management plans.