Effects of Grassland Biomass Harvest on Nesting Pheasants and Ducks

Abstract

Grasslands enrolled in conservation programs provide important habitat for nesting game birds and waterfowl, but conservation grasslands have been targeted as a source of biomass for bioenergy and this could impact nesting birds. We studied the effects of biomass harvest on nest success and density using 109 blue-winged teal (Anas discors), mallard (Anas platyrhynchos), and ring-necked pheasant (Phasianus colchicus) nests found in southwestern Minnesota during 2009 (pretreatment) and 2010 (posttreatment). Grassland biomass was harvested in late autumn of 2009 with production-scale machinery. Harvest treatments included controls (0% biomass removal), partial harvest (50 or 75% biomass removal), and full harvest (100% biomass removal) from 8 ha plots. Nest success averaged 31% and was not influenced by biomass harvest. Daily survival rates were greater for nests located closer to wetlands. Estimated total nest density (0.42 nests ha 21 ; corrected for survivorship) was similar across harvest treatments, but within-plot analysis revealed nest density was greater in unharvested refuge regions. Estimated nest density was positively correlated with vegetation height and the spatial extent of wetlands surrounding each plot. Harvesting relatively small-scale patches of conservation grasslands in late autumn does not appear to be detrimental to nesting ducks and pheasants the following spring, but managers should consider leaving unharvested refuges near wetlands when harvesting large continuous tracts.

Contrasting nest survival patterns for ducks and songbirds in northern mixed‐grass prairie

“…Similar to our results, duck nests located near wetlands in western Minnesota were less likely to be successful (Thompson et al 2012). Contrary to our findings, survival was greater for duck nests located closer to wetlands in Minnesota Conservation Reserve Program fields (Jungers et al 2015) but was independent of distance to wetland edge for ducks breeding in Saskatchewan, Canada (Pasitschniak-Arts et al 1998) and North Dakota (Horn et al 2005). We expected that nest concealment might affect nest survival, perhaps because more concealed nests are more difficult to locate by some predators or brood parasites.…”

Forage or Biofuel: Assessing Native Warm-Season Grass Production among Seed Mixes and Harvest Frequencies within a Wildlife Conservation Framework

“…Therefore, the primary advantages of NWSG polycultures over Switchgrass monocultures for biofuel production may be limited to wildlife conservation. Previous studies have observed plant communities among harvest frequencies in conservation grasslands similar to our NWSG plantings (Jungers et al 2015, Stahlheber et al 2016. However, increased cutting frequency can increase light availability, promoting photophilic plant species otherwise deterred by tall vegetation and dense grass canopies (Hautier et al 2009, Wilson andTilman 1991).…”