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Tuesday, 12 July 2016

Ardeola June 2016 : Volume 63 Issue 1

Published by: Spanish Society of Ornithology/BirdLife


Table of Contents
Jun 2016 : Volume 63 Issue 1


Ardeola, a Scientific Journal of Ornithology: Cooperative Survivorship within the Red Queen Game 
Mario Díaz, Eulalia Moreno, Juan A. Amat, Beatriz Arroyo, Emilio Barba, Jacob González-Solís, Paola Laiolo, Florentino de Lope, Santiago Merino, José Ramón Obeso and Alberto Velando

Ardeola is the scientific journal of the Spanish Ornithological Society. We analyse historical changes in citation, topics and foreign authorship of articles published in Ardeola from its first publication in 1954 up to last year, 2015, to test to what extent the persistence of the journal during the last 61 years has been due to support of authors, Society members, readers, editors or the whole ornithological community. Analyses were done within the context of the Red Queen game played by scientific journals competing for the best and more cited articles. The impact factor of Ardeola has increased from 1985 onwards both in absolute and relative terms. Thematic changes have followed trends of the general ornithological literature, without the journal specialising in particular topics or geographical regions. Foreign authorship decreased from 1954 up to the end of the 20th century, subsequently increasing again, a trend fuelled by coverage by Current Contents and the JCR, the establishment of English as the language of publication and recent Internet access through the BioOne platform. Ardeola is a traditional scientific journal, backed by a scientific society, whose future will be guaranteed by a reputation for rigour and quality sought by authors, reviewers and editors, supported by the members of the Spanish Ornithological Society and retaining its original objective: ‘to be a journal at the level of the best…, looking for a strong collaboration with foreign authors to promote the benefit of the Ornithology’.


What are We Learning about Speciation and Extinction from the Canary Islands? 
Juan Carlos Illera, Lewis G. Spurgin, Eduardo Rodriguez-Exposito, Manuel Nogales and Juan Carlos Rando

Oceanic islands are excellent systems for allowing biologists to test evolutionary hypotheses due to their relative simplicity of habitats, naturally replicated study design and high levels of endemic taxa with conspicuous variation in form, colour and behaviour. Over the last two decades the Canary Islands archipelago has proved an ideal system for evolutionary biologists who seek to unravel how biodiversity arises and disappears. In this review we have evaluated the contribution of the study of Canarian birds to our understanding of how and why species occur and change over time. We focus our attention on both extant and extinct Canarian taxa, and describe how research on these species has filled gaps in our understanding of avian speciation and extinction. In addition, we discuss the necessity of revising the current taxonomy in the Canarian avian taxa, especially the status of the endemic subspecies, some of which might be better treated as full species. An accurate classification of Canarian birds is not only necessary for testing evolutionary, biogeographic and ecological hypotheses, but also for effective decision making about conservation and environmental management. Finally we introduce future avenues of research that we feel will yield the most exciting and promising findings on island evolution in the coming years.

Brood Parasite-Host Coevolution in America Versus Europe: Egg Rejection in Large-Sized Host Species
Manuel Soler

The hosts of brood parasites have evolved egg-discrimination ability as a defence that allows them to reject parasitic eggs laid in their nests. Twenty-five years ago, Stephen Rothstein emphasised that rejection rates differed markedly between potential host species in Europe and America. The much more complete information available today supports Rothstein's conclusions, but also allows new ones, especially when considering host size. For instance, successful resistance, one of the three potential long-term outcomes of brood parasite-host coevolution, is considerably more frequent in small-sized European host species and in medium-sized and large-sized Nearctic host species, while this evolutionary outcome is rare among Neotropical hosts regardless of their size. These results have never before been discussed, despite the differences being spectacular: 17 out of 19 small hosts presenting successful resistance are from Europe and 16 out of 17 medium-sized and 11 out of 13 large hosts presenting successful resistance are from North America. Interestingly, many large Nearctic hosts with a rejection rate close to 100% are corvids. The high rejection capacity shown by large Nearctic potential hosts probably evolved as a response to a highly virulent extinct brood parasite, either a large extinct cowbird or an extinct cuckoo species, which went extinct after losing the arms race against its large hosts.

The Unknown Life of Floaters: The Hidden Face of Sexual Selection 
Juan Moreno

Sexual selection, as a form of social selection based on reproductive resources, is a crucial driver of evolutionary change. Many studies on sexual selection identify potential targets only within the reproductive fraction of populations. Floaters constitute the non-territorial fraction of the population, according to the usual definitions. Floaters have been identified through exhaustive capture and marking programmes, removal and nest-box addition experiments, extra-pair paternity studies, acoustic marking and genetic studies. The literature shows that floaters may represent a considerable fraction of populations, especially among males. There is no clear evidence that size, condition or testosterone level is necessary for explaining floater status generally. However, the literature suggests that ornament size and expression are involved in territorial exclusion and may be either its cause or one of its consequences. There is some evidence that floaters survive and reproduce less well than territorials, and that changes from floater to territorial status are accompanied by changes in survival and reproductive rates. However, certain male floaters may obtain some reproductive success through extra-pair copulations. The possibility that floating constitutes a successful alternative strategy in some species cannot be excluded, although the current preliminary consensus is that floaters are ‘making the best of a bad job’. Floater status may be imposed by limitations in the availability of mates or breeding space resulting in skewed population sex ratios, polygamous mating systems, high population densities and increased demand for specific breeding requirements such as space in colonies or adequate nesting cavities. Predictions concerning the effects of these factors have not been conducted to date. Few studies have been able to clarify the duration of floater status in any population. For short-lived species, floater status in a single breeding season may in fact imply zero lifetime reproductive success. In males, the existence of a considerable fraction of floaters attempting to breed may select for intense territorial behaviour and competitive mate guarding tactics in territory holders and in aggressive extrapair copulation and territory acquisition tactics in floaters. Interference competition from floaters may lead to density-dependent declines in reproductive success. In females, the attempts by floaters to attain breeding opportunities may have contributed to the observed propensities for female prospecting and for female-female aggression and the signalling of female dominance towards other females. Moreover, there may exist selection in females for signalling quality to mates in order to avoid being evicted by rivals. Excluding floaters from the analysis of sexually selected traits may severely affect sexual selection estimates because of biased sampling for large or more intensely expressed ornamentation. The importance of sexual selection may be negated or underestimated when in fact its action on floaters could be maintaining current levels of expression in the territorial fraction. Existing phenotypes should express, in their morphology, physiology and behaviour, the relentless drive through evolutionary time to avoid becoming a floater.

Differential Waterbird Population Dynamics After Long-Term Protection: The Influence of Diet and Habitat Type 
Alejandro Martínez-Abraín, Juan Jiménez, Juan Antonio Gómez and Daniel Oro

Using as a model system a long-term data set (1984–2014) of waterbird counts at nine large wetlands of Eastern Spain (Comunidad Valenciana), we explored the ecological drivers of population fluctuations, both during the wintering (34 species) and breeding (36 species) seasons. Most species showed increasing trends (80% during breeding, 62% in winter), including both initially common and rare species, suggesting a positive effect of site protection policies that were mainly applied in the 1980s. Specialised freshwater species such as diving ducks and coots did not show population recovery, most probably due to the characteristic tendency of shallow lagoons to remain eutrophic even after several decades of the implementation of sewage management and water purification. In fact re-introduction of a diet-specialist (red-knobbed coot) failed but that of a diet-generalist (purple swamphen) succeeded. Waterfowl hunting and the abandonment of rural practices also probably played a role in the lack of recovery by some species. Population trends of breeding species were more dependent on local conditions than trends of wintering populations. Body size could also have some influence on growth rates because some of the smallest species of shorebirds and Laridae (such as Kentish plovers, little terns and black-headed gulls) showed decreasing trends in one or both seasons. Finally, a few species were gained for the system as new wintering species, probably due to climate warming. Our results suggest that growth rates alone are poor descriptors of population fluctuations, especially for birds and other vagile taxa, and that it is more appropriate to interpret trends when considering natural regions spatially, and when growth rates are analysed within the time scale of the theoretical logistic curve.

Individual-Based Tracking Systems in Ornithology: Welcome to the Era of Big Data 
Pascual López-López

Technological innovations have led to exciting fast-moving developments in science. Today, we are living in a technology-driven era of biological discovery. Consequently, tracking technologies have facilitated dramatic advances in the fundamental understanding of ecology and animal behaviour. Major technological improvements, such as the development of GPS dataloggers, geolocators and other bio-logging technologies, provide a volume of data that were hitherto unconceivable. Hence we can claim that ornithology has entered the era of big data. In this paper, which is particularly addressed to undergraduate students and starting researchers in the emerging field of movement ecology, I summarise the current state of the art of individual-based tracking methods for birds as well as the most important challenges that, as a personal user, I consider we should address in future. To this end, I first provide a brief overview of individual tracking systems for birds. I then discuss current challenges for tracking birds with remote telemetry, including technological challenges (i.e., tag miniaturisation, incorporation of more bio-logging sensors, better efficiency in data archiving and data processing), as well as scientific challenges (i.e., development of new computational tools, investigation of spatial and temporal autocorrelation of data, improvement in environmental data annotation processes, the need for novel behavioural segmentation algorithms, the change from two to three, and even four, dimensions in the scale of analysis, and the inclusion of animal interactions). I also highlight future prospects of this research field including a set of scientific questions that have been answered by means of telemetry technologies or are expected to be answered in the future. Finally, I discuss some ethical aspects of bird tracking, putting special emphases on getting the most out of data and enhancing a culture of multidisciplinary collaboration among research groups.

Prioritising Research in Steppe Bird Conservation: A Literature Survey 
Manuel B. Morales and Juan Traba

With the aim to identify priorities in conservation-oriented research, this paper reviews the level of scientific attention given to steppe birds in Spain during the last 50 years. We surveyed scientific literature using Thomson Reuters Web of Science and the journal Ardeola, using the English names of 28 species of steppe birds and the word “Spain” as search terms. Every species was assigned a Scientific Attention Index (SAI), based on the number of articles published on each of them. In addition, a vulnerability measure (Vulnerability Score; VS) was calculated for each species on the basis of the trend estimate provided by the Sacre or Noctua monitoring programmes, or according to expert criteria. The sample gathered (432 articles) was a significant and thus representative proportion of WOS and Ardeola contents on the species considered. The most studied species was the red-legged partridge Alectoris rufa, with 83 papers (20.15%); while the least studied was the short-eared owl Asio flammeus (1 paper; 0.24%). The most studied knowledge area was Habitat Selection (92 papers; 22.17%), while the least was Niche/Climate, with nine papers (2.17%). Preferred habitat (grass steppe, shrub steppe or mixed) was not a significant factor in the level of scientific attention given to the different species. However, large-sized species (non-Passerines) were significantly more studied than small-sized ones (Passerines), indicating a research bias for the former group. Finally, no significant relationship was found between SAI and VS, which suggests that research effort has been allocated irrespective of the species' conservation status. These results highlight the scarce scientific attention given to most steppe birds in Spain in spite of their overall high vulnerability, and for most of the knowledge areas considered. On the other hand, they also show the high relative importance of research carried out in Spain, in both the Mediterranean and world contexts. This work underscores the need to focus scientific effort on certain species, especially those that currently show more regressive trends or higher levels of vulnerability, and in most areas of knowledge.

Birds in Ecological Networks: Insights from Bird-Plant Mutualistic Interactions 
Daniel García

Research in ecological networks has developed impressively in recent years. A significant part of this growth has been achieved using networks to represent the complexity of mutualistic interactions between species of birds and plants, such as pollination and seed dispersal. Bird-plant networks are built from matrices whose cells account for the field-sampled magnitudes of interaction (e.g. the number of plant fruits consumed by birds) in bird-plant species pairs. The comparative study of mutualistic networks evidences three general patterns in network structure: they are highly heterogeneous (many species having just a few interactions, but a few species being highly connected), nested (with specialists interacting with subsets of species with which generalists interact) and composed of weak and asymmetric relationships between birds and plants. This type of structure emerges from a set of ecological and evolutionary mechanisms accounting for the probabilistic role of species abundances and the deterministic role of species traits, often constrained by species phylogenies. Although bearing structural generalities, bird-plant networks are variable in space and time at very different scales: from habitat to latitudinal and biogeographical gradients, and from seasonal to inter-annual contrasts. They are also highly sensitive to human impact, being especially affected by habitat loss and fragmentation, defaunation and biological invasions. Further research on bird-plant mutualistic networks should: 1) apply wide conceptual frameworks which integrate the mechanisms of interaction and the responses of species to environmental gradients, 2) enlarge the ecological scale of networks across interaction types and animal groups, and 3) account for the ultimate functional (i.e. demographic) effects of trophic interactions.

Roles of Raptors in a Changing World: From Flagships to Providers of Key Ecosystem Services 
José A. Donázar, Ainara Cortés-Avizanda, Juan A. Fargallo, Antoni Margalida, Marcos Moleón, Zebensui Morales-Reyes, Rubén Moreno-Opo, Juan M. Pérez-García, José A. Sánchez-Zapata, Iñigo Zuberogoitia and David Serrano

Birds of prey have been, in comparison to other avian groups, an uncommon study model, mainly due to the limitations imposed by their conservative life strategy (low population density and turnover). Nonetheless, they have attracted a strong interest from the point of view of conservation biology because many populations have been close to extinction and because of their recognised role in ecosystems as top predators and scavengers and as flagship species. Today, after more than a century of persecution, and with the exception of some vultures still very much affected by illegal poisoning, many populations of birds of prey have experienced significant recoveries in many regions of Spain and the European Mediterranean. These changes pose new challenges when addressing the conservation of raptors in the coming decades. On this basis, and from a preferentially Mediterranean perspective, we have focused our attention on the need of describing and quantifying the role of these birds as providers of both regulating (rodent pest control and removal of livestock carcasses) and cultural ecosystem services. Moreover, we revisited persisting conflicts with human interests (predation of game species) and call attention to the emergence of new conflicts with a strong social and media component such as the predation on live cattle by vultures. Also, the rampant humanization of the environment determines the need for new solutions to the growing, yet scarcely explored, problem of accidents in new infrastructures such as mortality in wind farms. Finally, we explored in depth the ecological response of birds of prey to large-scale habitat changes such as urbanisation and abandonment of marginal lands that are also expected to increase in the near future. We urgently need more scientific knowledge to provide adequate responses to the challenge of keeping healthy populations of avian predators and scavengers in a rapidly changing world.

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