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A summary of 2015 breeding bird surveys of selected Rainwater Basin wetlands.
The Rainwater Basin is a landscape in south-central Nebraska (Figure 1) which is considered a key migratory stopover site, primarily in spring, for waterfowl and shorebirds in the Midcontinent of North America (Gersib 1989, 1992, LaGrange 2005). Due to this importance, recent studies have focused primarily on these bird groups during spring (Jorgensen 2004, Vrtiska and Sullivan 2009, Webb et al. 2010a, 2010b, Tidwell et al. 2013, Gillespie 2015). Less attention has been directed toward breeding birds that use Rainwater Basin wetlands. In fact, published information about breeding birds using Rainwater Basin wetlands is notably sparse and is limited to notable observations (Jorgensen 1994, 2003, Drahota 2003, Jorgensen and Dunbar 2005, Jorgensen 2012) and two studies focused on waterfowl (Evans and Wolfe 1967, Harding 1986) and one on Red-winged Blackbirds (Agelaius phoeniceus; Post van der burg 2005).
A key reason why less attention has been directed toward Rainwater Basin wetland breeding birds compared to spring migrants is because breeding bird use and diversity is unexceptional in the region. Rainwater Basin wetlands are dynamic since their principal source of water is precipitation run-off. Generally, Rainwater Basin wetlands collect water from snowmelt in late winter/early spring and increased precipitation during spring and early summer. Decreasing precipitation and increased evaporation and transpiration often results in decreasing water levels during the summer breeding season. It is not unusual for wetlands to dry completely during the summer. Thus, Rainwater Basin wetlands have short hydro-periods (LaGrange 2005). Rainwater Basin wetlands are also small and shallow compared to some other wetland types. The absence of relatively large, deep wetlands with relatively stable water levels likely limits the numbers of common bird species and overall diversity regularly nesting in Rainwater Basin wetlands.