Date of Award

12-1-1996

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Land managers have long debated the efficacy of available options for replacement plant communities and planted cover on previously disturbed soils. I used waterfowl nest success to evaluate planted cover types of Dense Nesting Cover (DNC) and Native Grass Planting (NP) from late April-early August 1994-95 on 39 Lonetree WMA study areas in central North Dakota. I was unable to detect a significant difference in waterfowl nest success between DNC and NP during 1994-95, despite major differences in cover height and density by visual obstruction reading (VOR) (P=0.001) and maximum height (P=0.02) measures by cover-year interaction. The power of our test would only allow us to detect a difference in Mayfield nest success of approximately > 15%.

Mean nest search densities were higher on DNC than NP for mallard (Anas platvrhvnchous) (P=0.0001), gadwall (Anas strepera) (P=0.0001), northern pintail (Anas acuta) (P=0.002), and total nest search density (i.e., all species of upland nesting ducks) (P=0.0001). Further, annual nest search densities were higher in 1995 compared to 1994 for blue-winged teal (Anas discors) (P=0.0002), and total nest search density (P=0.05). I believe that nest search density differences detected by cover type and year were due to differences in cover height and density, habitat use and nest site selection by nesting waterfowl, individual study area differences and availability of wetland complexes, and a return of higher than average rainfall during the evaluation period. To increase attractability of NP's to nesting waterfowl, I recommend that plant species diversity and heterogeneity of plant structure be increased on NP's.

A significant difference in waterfowl nest success was noted for both cover types combined in 1994 and 1995 (P=0.001). Mayfield nest success in 1994 and 1995 averaged 26% (95% C.I.=17-38%) and 9% (95% C.I.=6-14%), respectively. In part, I believe the difference in annual nest success was due to a decline in availability of small mammal prey (PcO.OOl) from 1994 to 1995 (primarily, Microtus spp. (P<0.001)}, density related factors, and predator related responses. Small mammal trapping conducted on Lonetree WMA in 1994 and 1995 by the N.D. Hantavirus Survey reported capture rate success of 16 and 10%, respectively for 1994 and 1995. Microtus spp. made up 31 and 13% of these captures in 1994 and 1995, respectively. Responses by avian and mammalian predators to differences in abundance of Microtus spp. reflected these changes.

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