Observaciones sobre relaciones cleptoparasitarias interespecíficas en el Alimoche (Neophron percnopterus)

S'aporten diverses observacions de cleptoparasitisme per part d'un aufrany adult sobre un voltor adult incubant, i també tres intents de corbs sobre nius d'aufranys amb polls. Les guineus també visiten els nius d'aufranys que són accessibles i aprofiten les deixalles que troben i en una ocasió, fins i tot, van predar un poll d'un mes d'edat

Managing non-native species: Don't wait until their impacts are proven

Peer Reviewe

Rapid loss of antipredatory behaviour in captive-bred birds is linked to current avian invasions

Despite the importance of behaviour in conservation biology, there have been few studies that address behaviour in areas such as invasion ecology. There is an urgent need to identify specific traits that facilitate the establishment and spread of alien species to prevent biological invasions and their impact on biodiversity. Changes in antipredatory behaviour in captivity have been proposed to explain the higher invasiveness of wild-caught exotic species. We experimentally tested this hypothesis by assessing the response of wild-caught and captive-bred cage birds facing an approaching predator and their ability to escape from human capture, using species available in the Spanish pet market. Results showed the loss of antipredatory responses and escape abilities in captive-bred birds compared with wild-caught ones. An intraspecific comparison between wild-caught and the first generation of captivebred birds pointed to a rapid behavioural loss in captivity (individual lifetime) rather than to differences among species (evolutionary exposure). In the context of current avian invasions, the proportion of individuals showing antipredatory responses within a species was positively related to the likelihood of the species being found escaped and breeding in the wild. These results offer a link between behaviour, fitness, and the invasion syndrome in birdsPeer reviewe

Habitat fragmentation affects culture transmission: Patterns of song matching in Dupont's lark

1. Males of many bird species match song with neighbours during territorial interactions. Although bird vocal mimicry has received much attention, the relationships between song variation and ecological factors such as landscape geometry and habitat fragmentation are still poorly known, and most previous research has been limited to one or a few populations of a species. In this study we analysed the spatial patterns and ecological determinants of song matching in Dupont's lark Chersophilus duponti, a rare and specialized steppe passerine. 2. By recording bird songs from 21 Spanish and Moroccan localities, we analysed the effect of habitat fragmentation and the availability of suitable steppe habitat on the patterns of song matching in Dupont's lark, controlling for other potential determinants such as period in the breeding season, intensity of competition, geographical location and spatial distribution of individuals. 3. Both song-type sharing (match of song types in the repertoire) and spectrotemporal matching (convergence in the acoustic features of the same song type) were greater between counter-singing neighbours than between non-neighbours, and spatial autocorrelation (similarities between singing individuals) only occurred at short distances. The study localities differed in the amount of overall acoustic matching between individuals, seemingly as a consequence of local differences in the intensity of male competition and in the availability of suitable habitat. 4. The levels of song-type sharing between non-neighbours tended to increase and those among neighbours to decrease with the increase of steppeland availability. Moreover, the existing differences in sharing between neighbours and non-neighbours were significantly affected by the presence of elements of fragmentation in the steppe. In fragmented habitats, song sharing among neighbours was enhanced, possibly because of harsher competition for limited resources; conversely, sharing among non-neighbours dropped, probably because of the lack of interactions among individuals isolated by habitat barriers. 5. Synthesis and applications. Anthropogenic habitat barriers could alter bird perception of the spatial distribution of rivals over distance, leading to a contraction of the spatial range of the individual acoustic niche. We suggest that communication systems of habitat-sensitive species might be used as a behavioural indicator of anthropogenic environmental deterioration. Because of their rapidly evolving cultural nature, bird vocalizations might become an early warning system detecting the effects of fragmentation over relatively short times and before other indicators (such as genetic markers) show any change. © 2005 British Ecological Society.Peer Reviewe

Possible predation by Little Owl (Athene noctua) on nestling Red-billed Choughs (Pyrrhocorax pyrrhocorax)

Durant l'any 1992 es va fer un seguiment de 73 nius de gralla de bec vermell situats dins de masos als Monegros. En una ocasió es van trobar plomes de gralla de bec vermell amb signes de predació de rapinyaire prop d'un niu de mussol, i en una altra ocasió es van trobar restes òssies d'un poll de gralla en un niu de mussol. Això suggereix que les gralles de bec vermell poden patir la predació per part dels mussols

Restricted gene flow and genetic drift in recently fragmented populations of an endangered steppe bird

Identifying the genetic processes derived from habitat fragmentation is critical for the conservation of endangered species. We conducted an integrated analysis of genetic patterns in the endangered Dupont’s lark (Chersophilus duponti), a circum-Mediterranean songbird threatened by the loss and fragmentation of natural steppes in recent decades. After sampling all the remaining Spanish populations and the two clos¬est North African ones, we found that the Mediterranean Sea acts as a major barrier against gene flow and that recent habitat fragmentation is isolating Spanish populations at different spatial scales. While we found a historical signal of gene flow among Spanish regions, a coalescent model supported that the ancestral panmictic population is evolving into several different units in the absence of current gene flow, genetic drift being more intense in the smaller and more isolated populations. Moreover, small-scale spa¬tial autocorrelation analyses showed that genetic differentiation is also acting within populations. The spatial genetic structure, significant levels of inbreeding and high relatedness within patches raise con¬cerns on the viability of most of the extant populations. We highlight the urgency for steppe patches to be protected, expanded and reconnected, considering the genetic clusters identified here rather than the previously considered eco-geographic regions occupied by the species. Meanwhile, translocations could be considered as a complementary, faster management action to attenuate the crowding and genetic effects of population fragmentation and the extinction risk of small populations without compromising the current local adaptations, culture diversity and genetic clusters already known for the species.Peer Reviewe

Is cell-mediated immunity related to the evolution of life-history strategies in birds?

According to life-history theory, the development of immune function should be balanced through evolutionary optimization of the allocation of resources to reproduction and through mechanisms that promote survival. We investigated interspecific variability in cell-mediated immune response (CMI), as measured by the phytohaemagglutinin (PHA) assay, in relation to clutch size, longevity and other life-history traits in 50 species of birds. CMI exhibited significant repeatability within species, and PHA responses in chicks were consistently stronger than in adults. Univariate tests showed a variety of significant relationships between the CMI of both chicks and adults with respect to size, development period and lifespan, but not clutch size or prevalence of blood parasites in adults. Multivariate analyses confirmed these patterns but independent variables were too highly correlated to isolate unique influences on CMI. The positive relationship of chick CMI to nestling period is further complicated by a parallel relationship of chick CMI to the age at testing. However, multivariate analysis showed that chick CMI varies uniquely with length of the nestling period. Adult CMI was associated with a strong life-history axis of body size, development rate and longevity. Therefore, adult CMI may be associated with prevention and repair mechanisms related to long lifespan, but it also may be allometrically related to body size through other pathways. Neither chick CMI nor adult CMI was related to clutch size, contradicting previous results linking parasite-related mortality to CMI and the evolution of clutch size (reproductive investment) in birds.Peer Reviewe

Presencia de gastrolitos y cáscaras de huevo en egagrópilas de Lechuza común (Tyto alba)

L'anàlisi de 787 egagròpiles d'òliba van mostrar la presència de 0,5% de gastrolites i 0,12% de restes d'ous de la mateixa espècie. Aquests dos elements rarament s'han esmentat a la bibliografia. La seva baixa freqüència suggereix l'ingesta accidental

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. © 2010 Society for Conservation Biology.Peer Reviewe

Effects of age and captivity on plasma chemistry values of the Egyptian Vulture

Despite the interest in blood chemistry for studying ecological and pathological characteristics of birds, sources of variability such as age and captivity are poorly understood, and reference values usually are obtained from adult captive birds. We determined 15 plasma chemical variables for 164 free-living Egyptian Vultures (Neophron percnopterus) of three age groups (nestlings, subadults, and adults), and for 9 captive adults. Free-living subadults and adults exhibited identical plasma chemistry values. Nestlings had significantly higher levels of creatinine, urate, urea, triglycerides, calcium, phosphorus, and alkaline phosphatase (AP) than both free-living subadults and adults, but lower values of glucose and aspartate aminotransferase (AST). Captive adults had significantly higher levels of total protein, albumin, creatinine, urate; cholesterol, calcium, phosphorus, and AST than free-living adults, which we attribute to differences in diet quality and physical activity. We conclude that future studies should consider age as a major source of variability in avian plasma chemistry, and that results obtained from captivity should be used cautiously to interpret plasma chemistry in the study and rehabilitation of wild birds.Peer Reviewe