Roberto Muriel

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.

Using manipulation of density-dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

1. Endangered species subjected to reintroduction programmes often occur as small and isolated populations with local high density and depressed fecundity. Variation in territory quality may lead to this low fecundity owing to increasing occupation of suboptimal territories as population density grows, known as the habitat heterogeneity hypothesis (HHH). In this context, food supplementation in poor territories may be used to produce extra young which could be allocated to reintroduction programmes. 2. We analyse the density-dependent fecundity pattern and the underlying mechanism in a small population of bearded vultures Gypaetus barbatus in Aragon (northeast Spain). We then use population simulations to examine the viability of a hypothetical reintroduction programme using extra young produced by supplementary feeding on poor-quality territories and the effect on the donor population. We also compare the economic cost of such a reintroduction programme in relation to the cost of a traditional captive breeding programme. 3. The wild population showed clear negative, density-dependent fecundity regulation driven by the HHH mechanism. Simulations showed that extractions for translocations had no relevant long-term effects on the donor population viability, but a marked population reduction during the extraction period. However, the implementation of supplementary feeding to produce extra young for translocation lessened significantly this expected initial population reduction. 4. Analyses showed that the annual budget of a captive breeding programme for this species could be seven times more expensive than the translocation of extra young produced by food supplementation. 5. Synthesis and applications. Reintroduction programmes based on translocation of wild-reared individuals, after a supplementary feeding programme oriented to poor-quality territories, provide a source of young at least seven times cheaper than those from captive breeding programmes. The use of this approach would decrease initial effects on donor population avoiding public criticism. Increasing the number of young released during the first years of the reintroduction decreases total financial cost and increases the final population size in the new area.

Sexual size dimorphism and sex determination by morphometric measurements in the Coscoroba Swan

The accuracy of morphological sexing and the occurrence of sexual dimorphism were analyzed in mature and immature Coscoroba Swans (Coscoroba coscoroba, Anatidae) near the Estação Ecológica do Taim, southern Brazil. On the basis of weight and 10 linear measurements of external morphology, multivariate analysis of variance showed that males were consistently larger than females (sex confirmed via genetic markers) and mature birds were consistently larger than immatures. Overall, 38% of immatures and 14% of mature birds were sexed incorrectly by cloacal examination when compared to genetic data. Therefore, we performed a discriminant function analysis of different age classes based on morphometric measurements. Mature birds were sexed with 96% accuracy using head and tarsus lengths as predictor variables, whereas immatures were sexed with 90% accuracy based on head and forearm lengths. Method validation conducted with data for additional mature sampled in a different year showed that the use of head length alone was as accurate for sexing (92% correct classification) than discriminant functions based on two characteristics (91%).

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

Juvenile dispersal behaviour and conspecific attraction: an alternative approach with translocated Spanish imperial eagles

The transient stage prior to definitive recruitment, known as juvenile dispersal, is thought to be under great evolutionary pressure and subject to a trade-off between associated costs and long-term benefits for fitness. Conspecific attraction has been shown to be an adaptive mechanism driving dispersal behaviours that may lead to negative density-dependent dispersal patterns. However, conspecific attraction can be scarcely discernible from imprinting to the natal area in wild populations. Reintroductions in the absence of settled individuals can be used as alternative colonization-like contexts to investigate the relative role of conspecific attraction in juvenile dispersal behaviours. We examined the spatiotemporal development of dispersal movements in reintroduced juveniles of a long-lived species with deferred maturity, the Spanish imperial eagle, Aquila adalberti , in comparison with nonmanipulated juveniles from a nearby population. We found that reintroduced birds started dispersal earlier and were initially more philopatric, probably encouraged by the advantageous competitive environment in the release area. Conversely, they revealed a more expansive strategy as they matured and approached the time when settlement decisions would be made, especially in females. They returned less frequently, increased exploratory movements and dispersal ranges, and visited breeding areas, probably as a consequence of the relatively lower reproductive prospects in the release area than in nearby populations. Therefore, the singular social cueing in reintroductions may eventually lead to juvenile wandering behaviours characteristic of colonization contexts in this territorial long-lived species. Such dispersive strategies relying on conspecifics may have important consequences for population dynamics and management. They may hinder the initial settlement phase in reintroductions, although behaviours such as longer returns may enhance recruitment prospects. Translocation programmes should consider specific dispersal scenarios, as well as postrelease monitoring to increase philopatry and success probabilities.

Factors affecting plasma biochemistry parameters and physical condition of Osprey ( Pandion haliaetus ) nestlings

AbstractWe assessed the normal values for 15 blood plasma biochemistry parameters and three indices of body condition (IBCs) in free-living Osprey (Pandion haliaetus) nestlings in Brandenburg (Germany). Values were compared with those of other raptors, and possible sexual and age-related differences were examined. In addition, we looked for possible relationships of habitat quality (measured in terms of foraging conditions and human disturbances) to nestling nutritional condition and productivity. Female nestlings showed higher mean urea levels and lower glucose values than males, which could be related to higher growth rates and nutrient demand of females at the end of the nestling period. Seven parameters also showed variation with age, probably relating to increasing body mass, metabolic rates, and physical activity during the pre-fledging stage. Conversely, the IBCs showed poor correlations with selected nutritional parameters, probably due to the homogeneously acceptable nutritional conditions of the nestlings. Finally, we found that Ospreys did not seem to adjust initial parental investment in relation to habitat quality, since productivity was not affected by habitat indicators. However, in large broods, but not in small ones, nestling nutritional condition improved as foraging conditions improved. These results suggest that females that are in better physical condition seem to produce more and better nourished nestlings in better foraging conditions.ZusammenfassungEinflussfaktoren auf biochemische Blutplasma-Parameter und körperliche Kondition nestjunger Fischadler (Pandion haliaetus) Wir beurteilten Normalwerte für 15 biochemische Blutplasma-Parameter und drei Indizes für die Körperkondition (Indices of Body Condition—IBCs) bei freilebenden nestjungen Fischadlern (Pandion haliaetus) in Brandenburg (Deutschland). Die Werte wurden mit denen anderer Greifvogelarten verglichen und mögliche geschlechts- und altersabhängige Unterschiede wurden untersucht. Zusätzlich haben wir denkbare Zusammenhänge zwischen der Habitatqualität—gemessen anhand der Lage von Gebieten der Nahrungssuche und anhand menschlicher Störung—und dem Ernährungszustand der Nestlinge sowie der Reproduktion untersucht. Weibliche Nestlinge zeigten höhere Harnstoff-Durchschnittswerte und geringere Glukose-Werte als männliche, was mit einer höheren Wachstumsrate und einem höheren Nährstoffbedarf bei den jungen Weibchen gegen Ende der Nestlingsperiode zusammenhängen kann. Sieben Parameter zeigten Veränderungen abhängig vom Alter, wahrscheinlich im Zusammenhang mit der zunehmenden Körpermasse, mit dem höheren Metabolismus und mit der steigenden körperlichen Aktivität während der Phase kurz vor dem Flüggewerden. Umgekehrt zeigten die IBCs geringe Korrelationen mit ausgewählten Parametern bezüglich der Nährstoffversorgung, wahrscheinlich aufgrund angemessener und gleichmäßiger Versorgung der Nestlinge. Schließlich fanden wir, dass Fischadler ihre ursprünglichen elterlichen Investitionen vermutlich nicht der Habitatqualität anpassten, da die Reproduktion nicht von den Habitateigenschaften beeinflusst wurde. Jedoch verbesserte sich die Nährstoffversorgung in großen Bruten mit besseren Bedingungen zur Nahrungssuche, nicht aber in kleinen Bruten. Unsere Ergebnisse legen es nahe, dass Weibchen mit besserer Körperkondition mehr und besser ernährte Jungvögel hervorbringen, insbesondere unter besseren Bedingungen für die Nahrungssuche.

Plasma alkaline phosphatase as a sensitive indicator of age and skeletal development in wild coscoroba swans

Context. Recent studies have suggested that plasma alkaline phosphatase (ALP) can be used to assess skeletal development as well as health status in wild animals. Aims. However, the information about age-related dynamics of ALP in birds, especially in precocial species, is very scarce. Therefore, before ALP measurements can be effectively interpreted, it is necessary to determine its normal variation for each species, age group and sex. Methods. Here, we report total-ALP levels of free-living coscoroba swans (Coscoroba coscoroba) from the most important breeding and moulting population in Brazil. Data were gathered during the moulting period and categorised according to sex and the following three different age classes: chick (n = 11), young (n = 14) and mature (n = 29). Key results. ALP levels were related to the longitudinal measure of the bones, gradually diminishing with age and showing significant differences among birds of different age classes. In all age groups, no effect of sex on T-ALP concentration was detected. Conclusions. We conclude that measuring ALP facilitates the discrimination among different-aged individuals with similar plumage characteristics and body size.

Blood Chemistry of Wild Brazilian Coscoroba Swans during Molt

The Coscoroba Swan (Coscoroba coscoroba) is an unusual member of the Anatidae found in South America, from the Falkland Islands and Tierra del Fuego through Chile and Argentina, Uruguay, and Paraguay as far north as Mato Grosso do Sul in Brazil. The species is not threatened globally, but some local populations have declined and the status of others is unknown. The objective of this study was to quantify the plasma chemistry of a wild population of Coscoroba Swans in southern Brazil during their molting period. We captured 12 chicks, 14 juveniles, and 31 mature birds. The following blood parameters were measured: glucose, cholesterol, triglycerides, HDL cholesterol, uric acid, creatin-kinase, aspartate amino transferase, alanine-aminotransferase, alkaline phosphatase, amylase, and pancreatic amylase. Significant differences between males and females were not observed for any of the parameters, and only the levels of alkaline phosphatase differed significantly among age groups.

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

Productivity is related to nest site protection and nesting substrate in a German Osprey population

AbstractThe Osprey (Pandion haliaetus) is an emblematic example of conservation. Currently, the species is progressively recovering in population size and range after dramatic reductions as a consequence of human persecution and the use of pesticides in the nineteenth and twentieth centuries. Here, we analysed the population trend and productivity in relation to the nesting substrate (artificial structures or trees) and the protection status of the nest location (inside or outside protected areas) in the eastern German population of Ospreys. The Osprey population steadily grew during the study period (2000–2009), accompanied by the increased use of artificial structures for nesting, possibly due to the scarcity of suitable natural nest sites in the region. Pairs nesting in trees showed higher variance in productivity than those nesting on artificial supports during the study period. Further, the productivity recorded in Ospreys nesting on natural sites decreased during the study period, regardless of the protection status of the nest location, whereas it did not vary for pairs nesting on artificial structures. The productivity of Ospreys was also related to the protection status of the nest location since pairs breeding inside protected areas, either in natural or on artificial nest sites, showed higher productivity than pairs nesting outside protected areas. These findings suggest that the protection of the nest location and the type of substrate used for nesting are relevant factors underlying the breeding performance in this Osprey population and are therefore key to its management.ZusammenfassungReproduktion des Fischadlers hängt vom Schutzstatus der Horstumgebung und vom Nistplatztyp ab Der Fischadler (Pandion haliaetus) ist ein Wahrzeichen für erfolgreichen Artenschutz. Nach dramatischem Rückgang durch menschliche Verfolgung und Pestizide im 19. und 20. Jahrhundert stieg die Populationsgröße in den letzten Jahrzehnten wieder an, und in vielen Regionen hat sich auch das Areal vergrößert. Hier analysieren wir den Populationstrend und die Reproduktion von Fischadlern in Ostdeutschland in Abhängigkeit vom Nistplatztyp (künstliche Strukturen vs. Bäume) und dem Schutzstatus des Nistplatzes (innerhalb vs. außerhalb von Naturparks, Biosphärenreservaten und einem Nationalpark). Die Fischadlerpopulation ist im betrachteten Zeitraum 2002–2009 stetig gestiegen, wobei—wohl in Ermangelung geeigneter alter Nistbäume—zunehmend anthropogene Strukturen, vor allem Gittermasten genutzt werden. Paare, die auf Bäumen nisten, zeigen eine höhere Varianz in der Zahl der Nachkommen als Paare, die auf künstlichen Strukturen nisten. Die Reproduktion der Fischadler auf natürlichen Nistplätzen hat im Verlauf der Untersuchungszeit abgenommen, unabhängig vom Schutzstatus der Umgebung. Dagegen hat sich Reproduktion der Fischadler auf künstlichen Strukturen nicht verändert. Paare innerhalb von Schutzgebieten hatten eine höhere Produktivität als Paare außerhalb von Schutzzonen, egal ob auf natürlichen oder künstlichen Nistplätzen. Die Ergebnisse weisen darauf hin, dass Schutzgebiete und der Nistplatztyp für die Reproduktion in dieser Fischadlerpopulation und ihr Management relevant sind.