| North American grassland bird populations have declined precipitously in the last 35 years. Habitat loss has been the most common cause implicated for the diminishing number of birds. Since the 1900s, >95% of native prairie has been lost in the Midwest.; In 1997, a 3-year study was initiated to evaluate the impact of Wildlife Production Areas (WPA) planted to either switchgrass (Panicum virgatum ), a native warm-season grass, or timothy (Phleum pratense ), an introduced cool-season grass, on grassland passerine populations in central Ohio. Specifically, my objectives were to examine the relationships among: (1) vegetative characteristics, (2) bird abundance, (3) arthropod populations, and (4) bird reproductive parameters.; Switchgrass WPAs have taller, more dense vegetation with a deeper litter layer than timothy WPAs. Three species, (red-winged blackbirds [Agelaius phoeniceus], song sparrows [Melospiza melodia ], and common yellowthroats [Geothlypis trichas]), comprised >80% of the birds recorded. Red-winged blackbird and song sparrow abundance did not differ between habitats. All grassland passerines combined were more abundant in timothy only during 1997.; A total of 1,398 nests representing 18 species were located. Red-winged blackbirds accounted for 88.3% of the nests, and they were more successful in switchgrass than in timothy WPAs. Predation was the most common cause of nest failure and success rates were <10% for several grassland bird species of conservation concern in Ohio (e.g., grasshopper sparrow).; Ten arthropod groups (Araneae, Acrididae, Pentatomidae, Miridae, Cercopidae, Curculionidae, Chrysomelidae, Tenebrionidae, Diptera, and Lepidoptera) were more numerous in timothy than switchgrass WPAs. Despite differences in arthropod abundance between WPAs, there was no difference in red-winged blackbird egg volume or nestling growth rates between habitats.; The low abundance of grassland passerines and the extremely low nest success for some species (e.g., grasshopper sparrow) are disappointing. Low abundance and low nest success of obligate grassland breeding birds suggest that the WPA program has little positive effect on statewide or regional grassland bird populations. |
