Priorities for Future Research

Almost nothing is known about the density and distribution of wintering Semipalmated Plovers, their overwintering survivorship, juvenile dispersal, or survival. Which birds oversummer on wintering grounds, and why, is also a subject of conservation significance. Similarly, there are few studies on foraging ecology during migration and the pattern of mass fluctuation over winter. There are also few data on sexual differences in migration because most observers do not sex individuals. The congeneric Common Ringed Plover exhibits a pattern of leapfrog migration; whether Semipalmated Plovers do this is unknown.

More information is needed on vocalizations, especially their context. Do subtle differences in the same calls used have different functions (Miller 1984)?

Why is this species rare compared to other shorebirds? The relationship between prey abundance and the abundance of Semipalmated Plovers has also not been addressed. Why in some areas is there consistent intraspecific aggression and in others little? Detailed examination of predator-prey relationships might help to answer this question. What regulates the population at any location remains largely unknown, and the seemingly late age at which first breeding occurs is also a puzzle. Although geographic variation in size has been reported, other data suggest that the patterns are not clear. We need morphometric data from more areas to resolve this question. Molt data are also very incomplete.

The degree of overlap in the breeding distributions of Semipalmated and Common Ringed plovers remains unresolved. Although expensive and logistically difficult, a survey of the putative zone of overlap would be most interesting.

A low level of extra-pair paternity in a subarctic breeding location is thought to relate, in part, to the very short breeding season. Given the wide latitudinal range in breeding of this species, DNA-fingerprinting of parents and offspring at northern temperate breeding locations, where the breeding season is longer than in the Arctic, would be a good test of the hypothesis. In Churchill, Manitoba, Killdeer are breeding at the northern edge of their range, Semipalmated Plovers in the center of their range. A study there of the energetics of these 2 species could shed light on what determines physiological limits of the geographic distribution of birds.