Fig. 1. (A) Natural antibody levels and (B) complement-mediated lysis in five species of shorebirds, estimated from the log₂-transformation of the score of the 1:2 serial dilution of the shorebirds' sera. Natural antibody levels were calculated at the step where agglutination stops and complement at the step at which lysis stops (see text for details). Values are means ± s.e.m.