Do northern lapwings Vanellus vanellus and little ringed plovers Charadrius dubius rely on egg crypsis during incubation

A b s t r a c t . We studied the possible role of clutch crypsis in antipredator behaviour in two related species of ground-nesting waders with camouflaged eggs, the northern lapwing (Vanellus vanellus) and the little ringed plover (Charadrius dubius). We examined whether this behaviour appears regularly in both species and tested the difference in the use of this trait between the two species. The results suggest that both charadriids rely on egg crypsis as a reasonable strategy toward avian nest predators. However, the larger and more conspicuous lapwings use it less frequently than plovers, probably because they rather rely on body size and aggressiveness combined with colonial breeding. Smaller and solitary little ringed plovers tended to hide the nest location more thoroughly than lapwings, probably due to their limited ability to defend the nest actively. Instead of aggressive attacks, they use alternative behavioural elements intended to deceive predators, namely incubation-feigning. Although egg crypsis is regularly used as a passive strategy for protecting nests against predators in both species, it seems to be unprofitable as an exclusive form of nest protection. The birds combine it with other behavioural elements, such as the above mentioned aggressiveness or incubation-feigning.