Great Plains                                    
    Cooperative Ecosystem Studies Unit

Description:  Surveys by Powell (2000) determined that National Park Servic units in the Great Plains provide breeding habitat for many species of grassland birds.  But, the relative value of the grassland habitats in NPS units to regional songbird production is unknown.  Are NPS grassland management regimes effective for producing songbirds?  Are NPS units too small to provide adequate habitat for grassland bird production?  Monitoring avian production requires documentation of nest survival, whish is prohibitively labor-intensive and expensive at a multi-park, regional scale.  Thus, park managers need lower-cost monitoring data for decision-making.  We propose an assessment of an emerging method, stable isotope analyses of avian tissues.  Stable isotope analyses may allow biologists to effeciently gauge the importance of grassland habitat patches to regional productivity.  Stable isotope analyses take advantage of regional gradients in ratios of isotopes in precipitation and/or vegetation (e.g., ¹H:²H, ¹³C:¹²C), that are expressed in the tissues of birds from a given location.  In forested habitats, biologists have used analyses of the variability in isotope values to infer that second-year ovenbirds (Seiurus aurocapillus) has lower fidelity to a study area than older individuals.  Our study is designed to evaluate whether stable isotope analyses can be extended to breeding grassland birds.  We plan to intensively monitor avian nest survival in three NPS units in the eastern Great Plains along a latitudinal gradient (Pipestone National Monument, Minnesota; Homestead National Monument, Nebraska; and Tallgrass Prairie National Preserve, Kansas).  We will sample feathers and blood from nestlings and breeding adults, and we will determine stable isotope values for each sample.  Our study will focus on two target species of grassland birds, dickcissel (Spiza americana) and meadowlarks (eastern [Sturnella magna] or western [Sturnella neglecta]), which are common in the study parks (Powell 2000).  We will search for and monitor nests of target species at each study location, and we will compare nest survival data to rates of breeding fidelity, as estimated by stable isotope values.  Our team of collaborators includes wildlife biologists with USGS, Canadian Wildlife Service, and the University of Nebraska, as well as NPS personnel.  If the technique works as predicted, NPS could adopt this monitoring scheme region-wide.  The information from such an exercise would provide critical answers to support management decisions, at a smaller cost than traditional avian monitoring methods.  Our project will provide critical avian demographic information, which will allow park managers to prioritize grassland bird management in relation to other management objectives.

Craig Allen, U.S. Geological Survey, Nebraska Cooperative Fish & Wildlife Research Unit
Larkin Powell, University of Nebraska-Lincoln
Keith Hobson, Canadian Wildlife Service
Gary Willson, Research Coordinator, GP-CESU, National Park Service

FY 2007-2009, $212,142