Northern Prairie Wildlife Research Center
More than 95% of native tallgrass prairie has been destroyed and most remaining prairie lands are fragmented (Knopf and Sampson 1997). Loss and fragmentation of prairie habitats has resulted in a widespread decline of grassland bird species (Herkert et al. 1993). Unfortunately, the status of grassland birds on many National Park Service (NPS) areas is unknown. In 1997, the NPS identified grassland birds as a high-priority research need within the Midwest Region. Baseline inventories and long-term ecological monitoring programs are needed in NPS areas to monitor grassland bird population trends. This report includes the results of an initial baseline inventory of grassland and other species of birds at Tallgrass Prairie National Preserve (TAPR), located in the Flint Hills of Chase County, Kansas.
We conducted avian censuses from May 1998 through August 1999, using a combination of point count and transect methods to determine species distributions, relative abundance, and densities. We used survey data and incidental bird sightings to develop a bird checklist for the preserve. Breeding birds were surveyed using fixed-distance (50-m and 100-m radius) circular point counts and resident, migratory, and breeding birds were surveyed using strip transects 500-m long and 100-m wide. Points and transects were unequally distributed among all habitats at TAPR. To understand bird and habitat associations, we quantified habitat characteristics for grassland areas where breeding bird counts were conducted using standardized methods.
We identified 132 bird species within the preserve boundaries. Fifteen were considered to be grassland-associated species. The number of grassland-associated species we found at TAPR was typical of prairie ecosystems (Cody 1966, Wiens 1973, Zimmerman 1997). For the two main watersheds at TAPR, species diversity was significantly higher at Fox Creek than Palmer Creek during the breeding season as well as year-round.
Eastern meadowlark (Sturnella magna) and dickcissel (Spiza americana) comprised a large percentage of the total number of birds for all of the habitats. Both species are characteristic of tallgrass prairie and are capable of utilizing a variety of grassland habitat types. Bird species that had the highest relative abundance for a given habitat also had the highest densities as determined by strip-transects. Overall bird density was higher year-round for the Fox Creek gallery forest than the Palmer Creek forest. Bird densities within TAPR peaked in November 1998 when large mixed-species flocks of sparrows and longspurs were found on the preserve.
Unburned and ungrazed prairie had a higher percentage of litter and grass cover, deeper litter depth, higher plant density, and lower percent bare ground than burned and grazed prairie. The riparian/prairie habitat had the highest percent bare ground, forb cover, and forb density, and the lowest percent litter and grass cover, perhaps due to shading from trees and heavy cattle use in the riparian areas. The tallest grass height, highest plant density, and lowest percent forb cover were found in the brome (Bromus inermis) fields where this exotic dominated the landscape. Most of TAPR, however, consisted of burned and grazed prairie, where litter depth and grass height were lowest, because annual prescribed-burns removed the litter layer and grazing reduced vegetation height.
Eastern meadowlark and dickcissel were found in all of the grassland habitat types, but grasshopper sparrows (Ammodramus savannarum) were never observed within brome fields. Upland sandpipers (Bartramia longicauda) were most likely to be found in areas with short, sparse vegetation in the burned and grazed prairie. In contrast, the presence of red-winged blackbirds (Agelaius phoeniceus) was positively correlated with grass height within brome fields.
Many grassland species rely on a mosaic of habitat types for different aspects of their life histories (Johnson and Igl 1999). Fire and light- to moderate grazing can be important tools for maintaining landscape heterogeneity and promoting plant diversity (Sample and Mossman 1997). To best benefit birds, burns should be scheduled before the breeding season or in the fall and burned on rotation every 2 to 5 years with variable frequency and seasonality (Sample and Mossman 1997, Heiburt 1998). Most bird species respond best to light grazing intensities with a rotation grazing regime in which some sections are grazed while others are left ungrazed (Herkert et al. 1993). If possible, areas should be left ungrazed until late in the nesting season and grazing should be discontinued soon enough in the fall to allow vegetation regrowth before dormancy (Sample and Mossman 1997).