Lauren R. Dinan

Density Dependent Double Brooding in Piping Plovers (Charadrius melodus) in the Northern Great Plains, USA

Abstract. Piping Plovers (Charadrius melodus) are primarily monogamous birds that usually raise only one brood per season, but rare instances of double brooding have been documented. Piping Plovers breeding in the northern Great Plains, USA were studied in two locations: the Missouri River near the Gavins Point Dam (2005– 2013) and the lower Platte River (2008–2013). There were 25 confirmed instances of double brooding on the Missouri River across the 9-year duration of the study. There were no instances of double brooding observed locally on the lower Platte River. However, in 2013, two female Piping Plovers successfully hatched eggs and fledged chicks from nests on the lower Platte River and later were observed nesting for a second time on the Missouri River. Factors predicted to increase the frequency of double brooding are: early nest initiation, male biased sex ratio, age of breeding adults, and decreased nesting density. Our results indicate density is an important factor that accounts for some of the difference in the proportion of double brooding on the Missouri River compared to the lower Platte River. It is likely a combination of factors is responsible for this behavior, previously thought to be rare, in Piping Plovers.

Usurpation of an Interior Least Tern (Sternula antillarum athalassos) Nest by Piping Plovers (Charadrius melodus)

Abstract Nest usurpation is a strategy in which an individual or pair of one species takes over the nest of another species. This is the first documented occurrence of a Piping Plover (Charadrius melodus) pair usurping an Interior Least Tern (Sternula antillarum athalassos) nest. The Piping Plovers incubated the three Interior Least Tern eggs in the nest, and all three eggs hatched. The adult Piping Plovers accompanied and brooded the Interior Least Tern chicks for 1 day post-hatching, but we did not see the adult Piping Plovers nor the Interior Least Tern chicks after that day. The Piping Plovers likely usurped the Interior Least Tern nest because they developed hormonemediated broodiness after they lost the eggs from their two previous nesting attempts. When the Piping Plovers encountered an unattended Interior Least Tern nest with eggs, they instinctively took the nest and its contents as their own.