Reed warblers in the sense of this extraordinary book mainly encompass the Acrocephalus-group, but also — perhaps a bit surprising for those who did not follow the latest reconstructions based on molecular sophistry — the genera of Hippolais and Iduna (both arboreal clades), Nesillas (four endemics of the Malagasy region), Calamonastides (just C. gracilirostris), and Phragamaticola (only represented by the former Acrocephalus aedon). Apparently, changes of habitat from bushes to reeds and vice versa occurred several times during the diversification of the group, and have resulted in a large variety of life histories. As a result, this now clearly defined group is the ideal subject for comparative studies. The plethora of ecological and behavioural studies of — mainly — European acrocephalid warblers published in the past decades makes such an enterprise all the more interesting. The hot topics that have been successively en vogue in the biological and ecological sciences found their equivalent in reed warbler research. The authors bring all this information together in an evolutionary framework (how did it all come about), and at the same time test past hypotheses and findings against novel techniques and ideas. Their track records make them particularly suited for such an integrative enterprise, as both are well-known for detailed Acrocephalus-studies since the 1970s.
The strict focus on six genera of the Acrocephalidae makes sense in a comparative study on phylogenetic grounds, but a slightly wider cast would have made for interesting comparisons with close competitors from other families (like the Locustellidae, the sister group of the Acrocephalidae, as well as Panurus biarmicus, Remiz pendulinus, Cyanistes caeruleus, Emberiza schoeniclus). However, a thought-provoking chapter is devoted to the passerines inhabiting the swamps of the New World. The New World has never been inhabited by Acrocephalidae, despite the fact that many oceanic islands have been colonised by this successful group (where they often live in forests and shrubs, instead of swamps). Instead, the reedswamps on the other side of the Great Pond are the domain of wrens, ovenbirds and tyrant flycatchers, which in the past 60 million years have evolved in splendid isolation and show morphological traits that are remarkably similar to those of the Acrocephalidae. To live in extreme habitats with low plant diversity and uniform vertical growth of thick stems, these species evolved the same adaptations as acrocephalids had done, i.e. large feet, small wings and long narrow bills. Convergent evolution was also apparent in the ways high productivity of simple habitats worked out: North American sharp-tailed sparrows and the European Aquatic Warbler look alike in plumage and locomotion and have a promiscuous mating system without territoriality, no pair bonds, brood care by females only and high levels of multiple paternity. Of the six European Acrocephalus warblers, most are socially monogamous (male and female remain paired for the duration of a breeding season, care of offspring divided equally between the sexes), a trait typical for species inhabiting relatively food-poor habitats. Aquatic Warblers, living in more productive habitats (wet and low grasslands), are promiscuous and the bond between the sexes has dissolved altogether. In between these two extremes, any breeding system is possible, depending on local conditions. The advent of molecular techniques has greatly promoted our understanding of what is going on in those reedbeds, grasslands and shrubs; drab birds are far from drab in their behaviour! The well-spun tales of Seychelles Warbler, Aquatic Warbler and Great Reed Warbler attest to the fact that real life baffles the imagination. How many adaptations are needed to successfully raise chicks in a short breeding season (in the temperate zone), surrounded by a multitude of predators and a tricky brood parasite (the Cuckoo), when your mean adult life expectancy is only 1.4 years (but higher in the tropics), your wintering areas as far away as sub-Saharan Africa, the Indian Subcontinent and southeast Asia, and a complete moult cycle takes about three months? The answer is: as many as it takes. Compared to other genera, the life histories of reed warblers have been particularly well studied, in many parts of their extensive breeding range and in a variety of habitats. The authors did a splendid job by bringing this information together in an evolutionary and behavioural setting, a service to the interested birdwatcher for which we should be grateful. Indeed, standing in knee-deep water, ‘surrounded by the persistent stink of sulphuretted hydrogen’ (in the words of Philip Brown and Gwen Davies, in a reed-warbler monograph published more than 60 years ago), will never be the same after reading Leisler & Schulze-Hagen. The drone of singing acrocephalids takes on a different meaning, the observer becomes aware of acoustic properties of the habitat, sexual selection, the meaning of song flights, reed density and water height as triggers for food abundance and nest characteristics (and the negative relationship between vegetation cover and food abundance), what the bubbling call of a female Cuckoo portends, the significance of perches for the probability of Cuckoo parasitism, variations in Cuckoo egg rejection rates between sites and years, the advantages of premature fledging, straddling techniques whilst climbing in reedbeds, fat accumulation, the meaning of testes size (when he cuts open a dead warbler in spring), moult patterns in relation to migratory strategies… Nondescript birds? Forget it!
Evidently, none of these behavioural and morphological traits are surprising in itself, but the fact that so many have been studied in such detail in the reed warbler group, with clever experiments to boot, makes for understanding complicated life histories. To have such tales available in a single volume, in a readable style, is a treat. The book is a veritable Fundgrube of facts and ideas, well written, edited and indexed. References have been tapped up to and including 2011. The presentation is up to high standards. The phylogenetic affinities are, for example, consistently presented by using specific colours for genera or clades. The many graphs are clear and easily understood. The photographs support the text, and it is good to see that targeted photography brings so many rewards in terms of clarification, on top of being esthetically pleasing. The high quality of printing enhances the effectiveness of the illustrations. And above all, the fine blend of science and natural history is a reminder that both are crucial for our understanding of this complicated world. Indeed, as the authors say, we need a renaissance of natural history. RGB
Reg Moreau's magnum opus The Palaearctic-African Bird Migration Systems, posthumously published in 1972, did not cover the coastal wintering sites of waders in Africa. By then, the enormous importance of the Banc d'Arguin (Mauritania) for colonial breeding birds was already known following the first quantitative surveys of René de Naurois between March and August 1959 (published in French, hence not immediately receiving the international attention it should have had), who continued to pioneer the breeding birds in the early 1960s. In the late 1960s, vital information became available, via the activities of W. von Westernhagen, that the Banc d'Arguin was also a crucial wintering site for Palearctic waders, later on confirmed by French, British and Dutch research. The Dutch in particular, starting in 1980, made in-depth contributions towards understanding the functioning of the intertidal ecosystem (see, for example, the special issue of Ardea 78: 1–364, edited by Bruno Ens, Theunis Piersma, Wim Wolff and Leo Zwarts). The research continues till this very day, for how to reconcile the tremendous apparent carrying capacity for waders with a nutrient-poor seagrass-dominated intertidal system (Jan van Gils) and the presence of avian predators (Piet van den Hout)? The present book is a timely overview of the importance of the Banc d'Arguin for birds, especially because it brings together disparate sources often not available to the average birder. The book is essentially an annotated checklist, but the additional chapters on the history, environment, colonial breeding birds, waders and synecology are valuable bonuses which underline the importance of this West African intertidal jewel. Counts of colonial breeding birds (between 1959 and 1999) and waders (varying from 1.1 to 2.3 million between 1978/79 and 2001, but there are many methodological pitfalls associated with counts on this scale) have been summarized in tables. The future of the Banc d'Arguin as a refuge for wildlife is not secure, despite its status of National Park since 1976. Overfishing (not by the local Imraguen, but by industrial fleets of all nationalities), oil exploration, an influx of tourists generated by the new tarmac road from Nouakchott to Nouadhibou (running along the Banc d'Arguin) and engineering works at the mouth of the Senegal river are mentioned. Fortunately, the management of the National Park is well aware of these and other threats. The continuation of research provides a constant update of knowledge which is also available for conservation purposes, increasingly embedded in an ecoregional setting. For the visiting birder, this book should be much more than just a checklist; it is a reminder of the delicacy of this ecosystem and a warning to behave accordingly.
Mauritania is more than the Banc d'Arguin, and now Isenmann and co-authors have produced a bilingual publication covering the whole country “Birds of Mauritania”. This is an annotated checklist of birds with comprehensive information on the species' status, phenology, and distribution. Complete with introductory chapters on geography and climate, the history of ornithology in Mauritania, biogeography of Mauritanian breeding birds, the Palearctic-Afrotropical bird migration system in Mauritania.