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Piping Plovers and Least Terns of
the Great Plains and Nearby

A draft protocol for assessing piping plover reproductive success
on Great Plains alkali lakes

Introduction


Poor reproductive success hinders recovery of piping plovers in the northern Great Plains (Haig 1992, Ryan et al. 1993), where they are listed as threatened in the U.S. and endangered in Canada (Haig 1985, Sidle 1985). Surprising, this key aspect of demography is documented at relatively few alkali lakes even though such habitat supports two thirds to three fourths of the region's breeding population (Haig and Plissner 1993, Plissner and Haig 1997). Monitoring of reproductive success ranks among the top priority tasks for recovering the species (FWS 1994). This work is essential for assessing population status and results of habitat management efforts.

Reproductive success data are not easily obtained for piping plovers on Great Plains alkali lakes. These shallow, semi-permanent to permanent, "hypersaline" to "eusaline" wetlands (Cowardin et al. 1979) generally are associated with the Missouri Couteau, a rolling to hilly moraine that crosses the Dakotas to southeastern Alberta. Methodologies described for other breeding habitats such as Atlantic coastal beaches (Goldin 1994) fail to address challenges unique to alkali lakes.

Compared to coastal beaches and river sandbars, alkali lakes are multidimensional. Plovers will respond from all points around a lake to distress calls and then mob intruders. This type of mobbing makes it difficult to assign pairs to nests, especially where high nesting densities (>5 pairs/km²) occur.

Also, gravelly clay beaches typical of alkali lake nesting habitat tend to be dry and hard, like pavement, making it almost impossible to see plover tracks, which provide helpful behavioral and nest-finding cues at sandy riverine or coastal beaches (Goldin 1994). Predator tracks, which aid determination of nest fate and sources of predation, are likewise indiscernible on dry alkali lake beaches.

Yet, in spring, beach substrates may be so soft that nest sites cannot be approached, and the tracks left by investigators may serve as cues for predators.

Compared to young plovers in other habitats, chicks that are roughly 3 wk old can be hard to account for on alkali lake beaches, mainly because some wander far from their nest sites or fledge relatively early.

Lastly, infrequent occurrence of humans on alkali lakes means that plovers there may be less habituated and more reclusive than along the Atlantic Coast.

Investigators need training to accurately assess plover reproduction on alkali lakes, yet no comprehensive guidelines are available. Furthermore, inconsistent methodology and terminology limit communication among investigators and reduce the value of data gathered.

Standardized instructions are proposed herein to facilitate consistent, accurate, and minimally invasive monitoring of plover reproductive success on Great Plains alkali lakes. They should speed learning among persons beginning this endeavor and help minimize disturbance to nesting plovers. These guidelines represent the author's combined experience with more than 1,700 nest attempts by piping plovers on alkali lakes from North Dakota to Alberta.


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