.102 



The Great Plains — 0:ir Living Rcsinincs 



For further information: 



Terr\ L- Shatter 



National Biological Service 



Northern Prairie Science Center 



8711 37th St. SE 



Jamestown, ND 58401 



US reti fox [Vulpes viilpes). striped skunk 

 (Mephitis mephitis), and raccoon iPraiyoii 

 lotor) are common or numerous throughout the 

 region (Sargeant et al. 1993). Both red foxes 

 and striped skunks are important predators of 

 duck nests (Johnson et al 1989). and red foxes 

 also take many female ducks during the breed- 

 ing season (Sargeant et al. 1984). 



More than two-thirds of the Prairie Pothole 

 region is in Canada. Greenwood et al. (1987) 

 studied mallard nest success in that portion of 

 the region from 1982 to 1985. Their findings 

 were similar to ours: mallard nest success aver- 

 aged 12% and only 7 of 31 estimates on indi- 

 vidual areas reached or exceeded 15%. 

 Predators caused most nest failures. The authors 

 concluded that nest success in much of Prairie 

 Canada in 1982-85 was too low to maintain sta- 

 ble numbers of breeding mallards. 



The status of duck nest success in the recent 

 past in the Prairie Pothole region seems clear. 

 Nest success was too low for duck populations 

 to sustain themselves. Unless steps are taken to 

 improve duck nest success in the future, we will 

 likely see further declines in numbers of these 

 and possibly other waterfowl species. 



References 



Cowardin. L,M.. D.S. Gilmer, and C.W. Shaiffer. 1985. 

 Mallard recruitment in the agricultural environment of 

 North Dakota. Wildlife Monographs 92. 37 pp. 



Greenwood, R.J., A.B. Sargeant. D.H. Johnson. L.M. 

 Cowardin. and T.L. Shaffer. 1987. Mallard nest success 

 and recniitment in Prairie Canada. Transactions of the 

 North American Wildlife and Natural Resources 

 Conference 52:298-309. 



Johnson. D.H.. J.D. Nichols, and M.D. Schwartz. 1992. 

 Population dynamics of breeding waterfowl. Pages 446- 

 485 ill B.D.J. Batt. ed. The ecology and management of 

 breeding waterfowl. University of Minnesota Press. 

 Minneapolis. 



Johnson. D.H., A.B. Sargeant, and R.J. Greenwood. 1989. 

 Importance of individual species of predators on nesting 

 success of ducks in the Canadian Praine Pothole region. 

 Canadian Journal of Zoology 67:291-297. 



Kletl. A.T. T.L. Shaffer, and D.H. Johnson. 1988. Duck nest 

 success in the Prairie Pothole region. Journal of Wildlife 

 Management 52( 3 ):43 1 -440. 



Sargeant^ A.B. . S.H. Allen, and R.T. Eberhardt. 1984. Red 

 fox predation on breeding ducks in midcontment North 

 ■America. Wildlife Monographs 89. 41 pp. 



Sargeant, A.B.. R.J. Greenwood. M.A. Sovada, and T.L. 

 Shaffer. 1993. Distribution and abundance of predators 

 that affect duck production — Prairie Pothole region. U.S. 

 Fish and Wildlife Ser\ice Resour. Puhl. 194. 96 pp. 



Conservation 

 Reserve 

 Program and 

 Migratory 

 Birds in the 

 Northern 

 Great Plains 



by 



Douglas H. Johnson 



RolfR. Koford 

 National Biological Service 



U.S. Depailment of Agriculture programs 

 have mediated supply and demand of com- 

 modities and maintained the agricultural indus- 

 try, but several programs have also offered vari- 

 ous kinds of con.servation benefits. The 1985 

 Food Security Act (Farm Bill) featured the 

 Conservation Reserve Program (CRP), which 

 paid farmers to plant perennial cover on highly 

 erodible lands and to leave this land intact for a 

 10-year contract period. During that period we 

 conducted two studies to determine the value of 

 CRP fields to breeding birds in the northern 

 Great Plains. 



Methods 



In one investigation, we censused breeding 

 birds on about 400 fields in nine counties in 

 eastern Montana. North Dakota, South Dakota, 

 and western Minnesota (Johnson and Schwartz 

 1993). These four states have about 4 million ha 

 (9.9 million acres) of CRP land, which is near- 

 ly 30% of all land included in the program. 

 Most of these CRP fields were planted to mix- 

 tures of native and introduced grasses and 

 legumes. We compared the average estimated 

 density of breeding pairs in CRP fields in North 

 Dakota with the density in croplands in a ran- 

 dom sample of quarter-sections surveyed in the 

 state (see Igl and Johnson, this section). We 

 believe this is an appropriate comparison 

 because nearly all CRP lands would have been 

 in cropland without the program. In addition. 



North Dakota is the only state with comparable 

 information about bird populations in cropland. 

 Results are available for 1992 and 1993. 



In a second investigation, we examined daily 

 survival rates of nests (eggs and young), a key 

 component of reproductive success, on 1 1 CRP 

 fields in North Dakota and Minnesota in 199 1 - 

 93. For comparison with CRP fields, we also 

 studied an alternative habitat with a similar 

 breeding-bird community. We studied 1 1 idle 

 grassland fields on upland pans of federal 

 Waterfowl Production Areas (WPAs): their veg- 

 etation typically is planted to mixtures of 

 legumes and to gras.ses. 



Bird Populations and 

 Reproductive Success 



Seventy-three different species were counted 

 in the first study, most of these species were far 

 more common in CRP fields than in cropland 

 (Table 1). Differences were especially great for 

 several grassland species that had declined 

 markedly in the Breeding Bird Survey's Central 

 Region of North America between 1966 (when 

 the surveys began) and 1990. For example, lark 

 buntings (Calamospiza melanocorys) and 

 grasshopper sparrows {Am mod ram us savan- 

 na rum), whose numbers fell by about two- 

 thirds during that period, were about 10 and 16 

 times more common in CRP habitat than in 

 cropland. 



