Habitat fragmentation has been implicated as a major cause of population decline in grassland birds. We tested the hypothesis that a combination of area and shape determines the use of grassland patches by breeding birds. We compared both species richness and individual species presence in 45 wet meadow grasslands in the floodplain of the central Platte River, Nebraska. Bird data were collected through the use of belt transects and supplemented by walking and listening outside transects. Our data supported our primary hypothesis that perimeter-area ratio, which reflects both the area and shape of a patch, is the strongest predictor of both individual species presence and overall species richness. The probability of occurrence for all six common species (Grasshopper Sparrows, Bobolinks, Upland Sandpipers, Western Meadowlarks, Dickcissels, and Red-winged Blackbirds) was significantly inversely correlated with perimeter-area ratio. The probability of occurrence of Grasshopper Sparrows, Bobolinks, Upland Sandpipers, and Western Meadowlarks was also correlated with area. We conclude that species richness is maximized when patches are large (Ͼ50 ha) and shaped so that they provide abundant interior areas, free from the impacts of edges.

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While more and more studies are exploring the application of remote sensing in assessing biodiversity for different ecosystems, most consider biodiversity at one point in time. Using several remote-sensing-based metrics, we asked how well remote sensing can detect biodiversity (both aand b-diversity) in a prairie grassland across time using airborne hyperspectral data collected in two successive years (2017 and 2018) and at different periods in the growing season (2018). The ability to detect biodiversity using "spectral diversity" and "spectral species" types indeed varied significantly over a 2-yr timespan. Toward the end of the growing season in 2018, the relationship between field-and remote-sensing-based aand b-diversity weakened compared to data collected from the same season in the previous year. This contrasting pattern between the two years was likely influenced by prescribed fire, altered weather, and the resulting shifting species composition and phenology. These findings indicate that direct detection of aand b-diversity in grasslands should be multi-temporal when possible and should consider the effect of disturbances, climate variables, and phenology. We demonstrate an essential role for airborne platforms in developing a global biodiversity monitoring system involving forthcoming space-borne hyperspectral sensors.