Tallgrass prairie restoration: declines in prairie bird populations following restoration at Spirit Mound

Background/Question/Methods

Tallgrass prairie ecosystems throughout the United States have experienced habitat destruction and fragmentation on a massive scale, this has generated the rapid decline of many tallgrass prairie bird species. Understanding how prairie restoration affects prairie bird populations is essential to tallgrass prairie conservation efforts as a whole. To determine changes over a ten year period, at a tallgrass prairie restoration habitat, we conducted  a series of line transect surveys in 2013 and compared the findings to a series of similar surveys conducted in 2003. Bird species diversity, density, abundance, and breeding status were all assessed at Spirit Mound in southeastern South Dakota. We tested three hypotheses: (1) there would be an overall decrease in total bird diversity; (2) grassland species of concern would increase in diversity, density, abundance, and demonstrate increased breeding behavior; and (3) there would be a decline in density, abundance, and breeding behavior of other species. Two line transects, each 1 km long and 350 m apart, were setup . Sightings within 75 m of each transect were used to determine the density, and sightings outside of the transect area were recorded as relative abundance. To evaluate breeding status, free-wandering breeding bird surveys were conducted.

Results/Conclusions

Overall when comparing 2013 to 2003 findings we found a 14% decline in total bird diversity. Declines in total diversity were expected as homogenization of habitat was occurring with restoration efforts, however we did not expect a 46% decline in grassland species of concern. Grassland species of concern declined in both density and relative abundance values between study years. Some of these showed a decrease in breeding behavior but others, such as the Spiza americana (dickcissel) and Sturnella neglecta (western meadowlark), maintained the same breeding status. Most other species exhibited an increase in density and abundance, but some, such as Zenaida macroura (mourning dove) , demonstrated a decline in density and/or abundance. Changes in breeding behavior of other species had mixed results. Current restoration methods such as burning, mowing, and pesticide use may have negative effects on the diversity, density, abundance, and breeding status of grassland species of concern. It is possible that the issue lies in the timing of management practices, because management is being conducted over much of the nesting season. Altering the timing of these practices may be beneficial for grassland species of concern and for the overall preservation of bird biodiversity throughout the Great Plains.