Global patterns of diversity among the specialist birds of riverine landscapes

Abstract

1. Despite the growing view that biodiversity provides a unifying theme in river ecology, global perspectives on richness in riverine landscapes are limited. As a result, there is little theory or quantitative data on features that might have influenced global patterns in riverine richness, nor are there clear indications of which riverine landscapes are important to conservation at the global scale. As conspicuous elements of the vertebrate fauna of riverine landscapes, we mapped the global distributions of all of the world's specialist riverine birds and assessed their richness in relation to latitude, altitude, primary productivity and geomorphological complexity (surface configuration). 2. Specialist riverine birds, typical of high‐energy riverine landscapes and dependent wholly or partly on production from river ecosystems, occur in 16 families. They are represented by an estimated 60 species divided equally between the passerines and non‐passerines. Major radiation has occurred among different families on different continents, indicating that birds have evolved several times into the niches provided by riverine landscapes. 3. Continental richness varies from four species in Europe to 28 in Asia, with richness on the latter continent disproportionately larger than would be expected from a random distribution with respect to land area. Richness is greatest in mountainous regions at latitudes of 20–40°N in the riverine landscapes of the Himalayan mountains, where 13 species overlap in range. 4. Family, genus and species richness in specialist riverine birds all increase significantly with productivity and surface configuration (i.e. relief). However, family richness was the best single predictor of the numbers of species or genera. In keeping with the effect of surface configuration, river‐bird richness peaks globally at 1300–1400 m altitude, and most species occur typically on small, fast rivers where they feed predominantly on invertebrates. Increased lengths of such streams in areas of high relief and rainfall might have been responsible for species–area effects. 5. We propose the hypothesis that the diversity in channel forms and habitats in riverine landscapes, in addition to high temperature and primary productivity, have been prerequisites to the development of global patterns in the richness of specialist riverine organisms. We advocate tests of this hypothesis in other taxonomic groups. We draw attention, however, to the challenges of categorically defining riverine organisms in such tests because (i) rivers grade into many other habitat types across several different ecotones and (ii) `terrestrialisation' processes in riverine landscapes means that they offer habitat for organisms whose evolutionary origins are not exclusively riverine.

Habitat Utilization, Time Budget and Daily Rhythm of Ibisbill (Ibidorhyncha struthersii) in Daocheng County, Southwest China

“…There are many imponderables about the effects of climate change, geographical and altitudinal shifts in habitat suitability, and pressures on riverine habitat from tourism, grazing, infrastructure development and waste disposal, all of which could affect this riverine specialist (Buckton and Ormerod 2002). Further details of habitat requirements, dispersion and time and energy budgets will be required to answer the protection and conservation needs of this species.…”

“…Its range is centered on the Pamirs, Himalayas and Tibetan Plateau, but peripheral populations occur west to Turkestan and east to northern Burma (Baker 1929;Vaurie 1965;Pierce 1986;Knystautas 1996;Zheng 2011). The Himalayas and the Tibetan Plateau are the global center of diversity for birds specializing in high altitude riverine landscapes (Buckton and Ormerod 2002), and there the Ibisbill inhabits broad stony rivers at altitudes typically between 1,700 and 4,400 m. The Ibisbill feeds by probing under rocks or gravel on stream beds (Pierce 1986;Knystautas 1996). In China, some Ibisbills occur on the Qinghai-Tibetan Plateau and YunnanGuizhou Plateau, but they can also be found at lower altitudes eastward as far as the suburbs of Beijing city, Henan Province and Hebei Province (Zheng 2011).…”

Latitudinal Gradients of Biodiversity: Pattern, Process, Scale, and Synthesis

“…In general, species richness increased toward the equator (Anderson 1984; Blackburn & Gaston 1996a, 1997Buckton & Ormerod 2002;Cardillo 2002;Cook 1969;Currie 1991;Diniz-Filho et al 2002b;Gaston 2000;Rabinovich & Rapoport 1975;Rahbek & Graves 2001;Schall & Pianka 1978;Tramer 1974). Although methodological differences existed among studies, especially regarding the inclusion or exclusion of wintering ranges in the determination of species richness, results were correlated (Blackburn & Gaston 1996a, 1996b, 1997 or similar (Tramer 1974).…”

Phylogeography of the white-throated dipper Cinclus cinclus in Europe

“…Among specialist river birds (see Buckton and Ormerod 2002), five species make up the genus Cinclus in the family Cinclidae: Cinclus mexicanus, C. leucocephalus, C. schulzi, C. cinclus and C. pallasii. The phylogeny of this unique family (the only Passerines able to dive in fast-flowing streams and rivers) has been recently studied at the species level (Voelker 2002).…”