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Wetland Symposium

Population Response of Ring-Necked Pheasants to Cattail Fragmentation in North Dakota


North Dakota State University, Department of Zoology, Fargo, ND 58105-5517; North Dakota State University, Department of Zoology, Fargo, ND 58105-5517; U.S. Department of Agriculture, Denver Wildlife Research Center, North Dakota Field Station, Fargo, ND 58105-5517

In May 1992, we began a three-year study in southeastern North Dakota to determine the effects of fragmenting dense cattail (Typha spp.) stands on ring-necked pheasant (Phasianus colchicus) populations. Severe cattail reduction appears to decrease the use of wetlands by certain passerine species. However, the response of ring-necked pheasants to wetland fragmentation is unknown. Pheasants use semipermanent (Type IV) wetlands for cover during fall and winter.

We selected eight semipermanent cattail-choked wetlands (10-50 ha) and centered them within 23 km2 blocks. Pairs of blocks were matched on the basis of land use surrounding the central wetland (e.g., amount of CRP). Each block within a pair was randomly designated as treatment or control. All wetlands within the treated blocks were aerially sprayed with glyphosate herbicide (®RODEO formulation) in August 1992. The spray pattern consisted of 15-m treated strips alternated with 6.4-m untreated strips. A "no spray" buffer zone of 1.6 km surrounds each block.

Spring crow counts were started in May 1992 and will be conducted in May 1993 and 1994 to detect changes in population densities among treated and control blocks. Each pair of blocks was censused weekly over a 4-5 week period. Three strata, based on distances from the center wetland, were established in each block. Four listening stations, positioned in 0.8 km increments were randomly selected from each stratum. The order of the listening stations was reversed on alternating repetitions. One observer in each block began the counts one-half hour before sunrise and recorded the number of calls in a two-minute period at each station; the task was completed in about 1.5 hours. Censusing was done under conditions of wind velocities ≤16 km/hr, no rain, and temperatures ≥0° C.

In May 1992, number of pheasant calls did not differ between untreated (controls) and treated blocks (P = 0.311, Mean of X = 6.4, SE = 1.02). These pre-treatment counts will be compared statistically with counts obtained in May 1993 and 1994.

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