Fernando Hiraldo

CAUSES AND CONSEQUENCES OF TERRITORY CHANGE AND BREEDING DISPERSAL DISTANCE IN THE BLACK KITE

Factors affecting individual variation in between-year territory change and dispersal distance were measured in a long-term study of Black Kites (Milvus migrans) living in an area of ∼100000 ha in and around Donana National Park in southern Spain. Adult birds (N = 210) and fledglings (N = 3061) were individually marked, and breeding birds were monitored annually during 1989–1996 to detect banded individuals. Of these 3271 birds, 652 breeding birds were resighted, and 164 of them were sexed through copulatory behavior. Nests were checked annually to monitor breeding performance. Frequencies of return between years were 83.1% for breeding males and 89.5% for breeding females. Frequencies of territory change were 25.6% and 32.8%, respectively. Females >8 yr old rarely changed territories. Dispersing birds departed significantly more from low-quality territories (evaluated through breeding success variables). Breeding failure and mate loss (divorce or death) favored breeding dispersion, both in males and fema...

Factors Influencing Nest Site Selection, Breeding Density and Breeding Success in the Bearded Vulture (Gypaetus barbatus)

We examined the nest site selection, breeding density and breeding success in the bearded vulture Gypaetus barbatus in relation to physiography, climate, land-use and degree of human disturbance. The study area was in the Pyrenean Cordillera, Spain, where the largest European population of this species occurs. univariate analyses and Generalized Linear Models were employed. Models correctly classified the 78% of the cliffs analysed (occupied by bearded vultures, and selected at random). The probability of occupation of a cliff by bearded vultures was directly related to the ruggedness of the topography, altitude, distance to the nearest bearded vulture occupied nest, and distance to the nearest village

CAUSES AND FITNESS CONSEQUENCES OF NATAL DISPERSAL IN A POPULATION OF BLACK KITES

Natal dispersal is of central interest when determining demography and genetic structure of populations and managing endangered species with fragmented distributions. However, methodological limitations linked to spatial and temporal constraints have prevented studies of natal dispersal in long-lived birds. Moreover, the consequences of natal dispersal have mainly been related to the first breeding attempt rather than to lifetime reproductive success. We studied the causes and fitness consequences of natal dispersal in a population of Black Kites at Donana National Park (southern Spain). From 1986 to 1995 we marked 2929 nestlings with plastic numbered bands. We annually monitored marked birds in breeding territories, their breeding success, and the survival of nonbreeding birds. Additionally, we searched for marked birds in broad areas of the Iberian Peninsula and North Africa. Median natal dispersal distance was 4.8 km (N = 285), with males more often dispersing shorter distances and females dispersing at all distance categories equally. Density of conspecifics negatively affected dispersal distances of both males and females. In addition, single and first-hatched males born in areas with high breeding density dispersed shorter distances. Dispersal distances tended to be correlated between siblings, possibly a result of sharing similar environmental conditions. We did not find evidence that dispersal was an active mechanism aimed to prevent close inbreeding. Patterns of dispersal in this population are probably driven by intraspecific competition. Males that dispersed shorter distances showed higher lifetime reproductive success (LRS). LRS did not differ among females dispersing different distances, but females that dispersed farther mated with more experienced males. These sex differences in dispersal patterns and their consequences may be explained by the inequality between sexes in breeding roles in this species. Familiarity with the natal area could be important for males, which defend territories and resources, while females may increase their fitness through mate choice and breeding dispersal. High levels of philopatry in Donana National Park may be a result of a surplus of food resources and the effects of conspecific attraction in densely populated areas. However, the degree of philopatry may vary between populations and with time, subject to differences in ecological pressures.

Long-term effects of lead poisoning on bone mineralization in vultures exposed to ammunition sources

Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron percnopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10-1780 microg L(-1) n=137; Iberian Peninsula range: 5.60-217.30 microg L(-1) n=32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.

Phylogeography, genetic structure and diversity in the endangered bearded vulture (Gypaetus barbatus, L.) as revealed by mitochondrial DNA

Bearded vulture populations in the Western Palearctic have experienced a severe decline during the last two centuries that has led to the near extinction of the species in Europe. In this study we analyse the sequence variation at the mitochondrial control region throughout the species range to infer its recent evolutionary history and to evaluate the current genetic status of the species. This study became possible through the extensive use of museum specimens to study populations now extinct. Phylogenetic analysis revealed the existence of two divergent mitochondrial lineages, lineage A occurring mainly in Western European populations and lineage B in African, Eastern European and Central Asian populations. The relative frequencies of haplotypes belonging to each lineage in the different populations show a steep East–West clinal distribution with maximal mixture of the two lineages in the Alps and Greece populations. A genealogical signature for population growth was found for lineage B, but not for lineage A; futhermore the Clade B haplotypes in western populations and clade A haplo‐types in eastern populations are recently derived, as revealed by their peripheral location in median‐joining haplotype networks. This phylogeographical pattern suggests allopatric differentiation of the two lineages in separate Mediterranean and African or Asian glacial refugia, followed by range expansion from the latter leading to two secondary contact suture zones in Central Europe and North Africa. High levels of among‐population differentiation were observed, although these were not correlated with geographical distance. Due to the marked genetic structure, extinction of Central European populations in the last century re‐sulted in the loss of a major portion of the genetic diversity of the species. We also found direct evidence for the effect of drift altering the genetic composition of the remnant Pyrenean population after the demographic bottleneck of the last century. Our results argue for the management of the species as a single population, given the apparent ecological exchangeability of extant stocks, and support the ongoing reintroduction of mixed ancestry birds in the Alps and planned reintroductions in Southern Spain.

Individual improvements and selective mortality shape lifelong migratory performance

Billions of organisms, from bacteria to humans, migrate each year and research on their migration biology is expanding rapidly through ever more sophisticated remote sensing technologies. However, little is known about how migratory performance develops through life for any organism. To date, age variation has been almost systematically simplified into a dichotomous comparison between recently born juveniles at their first migration versus adults of unknown age. These comparisons have regularly highlighted better migratory performance by adults compared with juveniles, but it is unknown whether such variation is gradual or abrupt and whether it is driven by improvements within the individual, by selective mortality of poor performers, or both. Here we exploit the opportunity offered by long-term monitoring of individuals through Global Positioning System (GPS) satellite tracking to combine within-individual and cross-sectional data on 364 migration episodes from 92 individuals of a raptorial bird, aged 1–27 years old. We show that the development of migratory behaviour follows a consistent trajectory, more gradual and prolonged than previously appreciated, and that this is promoted by both individual improvements and selective mortality, mainly operating in early life and during the pre-breeding migration. Individuals of different age used different travelling tactics and varied in their ability to exploit tailwinds or to cope with wind drift. All individuals seemed aligned along a race with their contemporary peers, whose outcome was largely determined by the ability to depart early, affecting their subsequent recruitment, reproduction and survival. Understanding how climate change and human action can affect the migration of younger animals may be the key to managing and forecasting the declines of many threatened migrants.

Conservation status and limiting factors in the endangered population of Egyptian vulture (Neophron percnopterus) in the Canary Islands

Egyptian vulture populations have decreased sharply in the Western Palearctic; island populations are almost extinct in the Mediterranean and the Macaronesian regions. In the Canary archipelago, the species only survives in the islands of Fuerteventura and Lanzarote. During 1998–2001 we examined population parameters and evaluated some potential limiting factors for this isolated and sedentary population. The total population (breeding and non-breeding birds) was monitored annually. In addition, 26 fledglings and 33 immatures ( 6 years old birds) and immature annual survival rates were similar, around 90%. Adult survival was lower than expected as territorial birds seem more susceptible to poisoning. Immature survival could be favoured by the existence of regular feeding places. Casualties from power lines was the main cause of mortality (12 cases during the study period). Blood sampling revealed high frequencies of lead poisoning: 13.5 and 2.7% of individuals showed sub-clinical and clinical intoxication levels, respectively, probably caused by the ingestion of lead shot. Priority conservation measures should be directed to reduce electrocution risks, illegal poisoning, and lead contamination. Population reinforcement with birds coming from other populations is not recommended as previous information reveals morphological and genetic differentiation of Canarian Egyptian vultures compared with continental populations. # 2002 Elsevier Science Ltd. All rights reserved.

The paradox of the Long-Term positive effects of a north american crayfish on a european community of predators

Invasions of non-native species are one of the major causes of losses of native species. In some cases, however, non-natives may also have positive effects on native species. We investigated the potential facilitative effects of the North American red swamp crayfish (Procambarus clarkii) on the community of predators in southwestern Spain. To do so, we examined the diets of predators in the area and their population trends since introduction of the crayfish. Most predator species consumed red swamp crayfish, which sometimes occurred in over 50% of their diet samples. Moreover, the abundance of species preying on crayfish increased significantly in the area as opposed to the abundance of herbivores and to predator populations in other areas of Europe, where those predators are even considered threatened. Thus, we report the first case in which one non-native species is both beneficial because it provides prey for threatened species and detrimental because it can drive species at lower trophic levels to extinction. Increases in predator numbers that are associated with non-native species of prey, especially when some of these predators are also invasive non-natives, may increase levels of predation on other species and produce cascading effects that threaten native biota at longer temporal and larger spatial scales. Future management plans should include the complexity of interactions between invasive non-natives and the entire native community, the feasibility of successful removal of non-native species, and the potential social and economic interests in the area.

Causes of natal dispersal in the lesser kestrel: Inbreeding avoidance or resource competition?

1. Natal dispersal of seven cohorts (1988-94) of the colonial lesser kestrel (Falco naumanni) was studied in southern Spain. We ringed 1852 nestlings and resighted 321 (17.3%) which survived at least the first migration to Africa. Of the returning individuals, 57% settled in their natal colonies and the remaining 43% dispersed to other colonies. Resights fell off markedly with increasing distance from the natal colony; more than 90% of resights were within 30 km of the birthplace. 2. Contrary to most avian studies, dispersal from the natal site was not sex-biased in our population. The proportion of dispersing males (41%, n = 171) did not differ significantly from that of females (45%, n = 150). Excluding philopatric individuals, the median dispersal distance for males (19 km) did not differ from that of females (18.5 km). 3. Siblings (72 twos) dispersed or were philopatric independently of each other. This result provides no support for either a genetic basis of dispersal (which predicts the same strategy for both siblings) or the inbreeding avoidance hypothesis (which predicts greater dispersal in one sex than the other). This latter hypothesis also conflicts with our observation that the presence of the parent of the opposite sex in the natal colony has no effect on whether returning individuals disperse. 4. Generalized linear models (GLMs) showed that the probability of dispersal for an individual increased when the absolute growth of its natal colony decreased and also from beginning to end of the study, coincidental with a general population increase. These results point to a link between colony saturation and dispersal. GLMs also showed that dispersal distances tended to increase with size of the natal colony and higher breeding success. These results are also consistent with intraspecific competition for resources. 5. Some individuals were observed in two different colonies in their year of first return. These observations, and the lack of active inbreeding avoidance, suggest a scenario for the dispersal process: individuals would prefer to settle in their natal colonies. If they cannot secure a nest site or a mate, they will have to decide whether to stay as nonbreeders or to disperse in search of another breeding chance elsewhere. The actual decision to disperse could be triggered by the level of aggression the unmated individuals encounter in their natal colonies.

Ecological, morphological and phylogenetic correlates of interspecific variation in plasma carotenoid concentration in birds

Carotenoids are important as pigments for bright coloration of animals, and as physiologically active compounds with a wide array of health‐related benefits. However, the causes of variation in carotenoid acquisition and physiology among species are poorly known. We measured the concentration of carotenoids in the blood of 80 wild bird species differing in diet, body size and the extent of carotenoid‐based traits. Preliminary analyses showed that diet significantly explains interspecific variability in plasma carotenoids. However, dietary influences were apparently overridden by phylogenetic relationships among species, which explained most (65%) of this variability. This phylogenetic effect could be due partly to its covariation with diet, but may also be caused by interspecific differences in carotenoid absorption from food to the blood stream, mediated, for example by endothelial carriers or gut parasites. Carotenoid concentrations also decreased with body size (which may be explained by the allometric relationship between ingestion rate and body mass), and correlated positively with the extent of carotenoid‐dependent coloration of plumage and bare parts. Therefore, the acquisition of carotenoids from the diet and their use for both health and display functions seem to be constrained by ecological and physiological aspects linked to the phylogeny and size of the species.