Published in HBW Volume 9 on page 699 (below).
Original HBW caption:
Despite their close taxonomic alliance, the Rock Pipit (Anthus petrosus) and the Water Pipit occupy very different ecological niches. The Rock Pipit is a bird of open rocky seashores and estuaries; it is almost always encountered at coastal sites, and it spends most of its time within the intertidal zone. A few individuals ascend to 400 m on hills slightly inland, and others breed on rocky islands in inland lakes. The Water Pipit, in turn, breeds at much higher altitudes, usually around streams or damp grassy areas between 650 m and 3200 m, and never at sea-level. The Rock Pipit is a partial migrant, but it always favours coastal sites, while the Water Pipit provides an interesting example of a seasonal switch in habitat selection. In winter it descends to the lowlands, frequenting freshwater habitats such as rice fields, coastal lagoons and waterlogged grassland. Some birds from Central European populations travel north to Britain, where they overwinter on watercress beds, and in other suitable habitats. Given these distinct and inflexible differences in habitat requirements and migratory patterns, it now seems remarkable that this complex was previously thought to contain no more than a single species, and even more surprising that this view held sway until 1998.