Shorebirds are part of the marine ecosystem. Although they have generally not been ronsidered within t.his group, the fact that almost 40 0 ; " of the species breed along coasts and more than 60 (1, often or always spend the non-breeding season in coastal habitats justifies their classification iis marine animals. They add about 217 species to the 280 that are tradit,ionally thought. of as marine. Their study provides unique opportunities to examine basic problems of behavior, ecology, and evolution. During the last twenty years, a veritable explosion of research activityivns initiated, and the results have been compiled in these two volumes. Many new data tire inrludcd. The first two sections of Volume 5 serve as nn introduction, that concerns itself with shorebird classification "and whether shorebirds are marine animals". Their role in the marine ecosystem and their habitat selection are also discussed. Subsequent sections deal with populat,iondynamics, breeding and social systems of sandpipers, the evolution of polyandry, evolution of parental behavior and clutch size. and anti-predator behavior. Finally, the conservation of Xexrrtic shorebirds is discussed in light of present dangers, including hunt,ing, habit,at manipulation, habitat loss and degradation loom. Volume 6 covers behavioral aspect.s during t.he non-breeding season, including abiotic factors affecting migration in t,he Western Palearctic and t,he Xew World, foraging and activity patterns, int.ake rates and food supply in wintering shorebirds, and spacing pat,terns of non-breeding populations. The habitats analyzed are primarily those of British and North American birds. Biological oceanographers who are not ornithologists may he rspecially interested in the effect of shorebirds on the benthic invertebrate fauna in coastal habitats, as int.ensively studied by Dutch biologists in t.he Waddensea.