In addition, the predator community on grassland-dominated landscapes is largely comprised of coyotes and badgers, which have relatively large home ranges compared to those of smaller predators, such as skunks and foxes. Larger home ranges mean fewer predators within a given area in search of duck eggs. Also, some studies suggest that rodent populations are more robust in areas with abundant grass cover, providing more buffer prey that could improve the odds for nesting birds.
The data also revealed a direct correlation between the abundance of upland cover and nest success within the four-square-mile study areas, while the level of grass in the surrounding 36-square-mile area seemed to have much less of an impact on nest success. This is good news for DU because it is much easier to positively influence land use on this smaller scale.
Interestingly, Stephens discovered that the type of upland cover in which ducks nested had little impact on their success. During both years, nest success for ducks in CRP and grazed native pasture was almost identical. He also observed that several shorebird species, including willets, marbled godwits, upland sandpipers, and Wilson's phalaropes, had very specific nesting cover preferences. "We didn't find shorebirds in anything other than native prairie," Stephens says. "If we continue to lose this habitat, those birds are going to disappear because, unlike most duck species, they won't use planted cover."
This research underscores the urgency of DU's efforts to save large remaining blocks of grassland and small wetlands, which are presently being lost at an alarming rate across the prairies. It also confirms the immense benefits CRP provides to waterfowl and many other prairie-nesting birds. "CRP fields clearly are very productive for breeding waterfowl in areas where large blocks of land have been enrolled in the program and where CRP fields augment extensive tracts of native pasture," Stephens says. "In many cases, CRP fields fill in the gaps between existing blocks of upland cover. If you lose those chunks of planted cover, nest success could plummet throughout surrounding landscapes."