Northern Prairie Wildlife Research Center
By the year 2001, conserve habitat capable of supporting 6.8 million breeding ducks that achieve a recruitment rate of 0.6 under average environmental conditions, with all managed areas achieving a recruitment rate of 0.49 at a minimum.
Note: Recruitment rate is defined as females fledged per breeding female. Managed areas are those leased or owned and managed for waterfowl production by state or Federal wildlife agencies and private conservation organizations.
The above objective would produce a fall flight of about 9.5 million birds, if 6.8 million breeding ducks recruited at a rate of 0.6. Under wet conditions, more than 6.8 million breeding ducks would be accommodated, and recruitment rates would exceed 0.6. Of the 6.8 million breeding ducks, stepped down from overall NAWMP objectives for average conditions and based on historical distributions, about 1.2 million mallards and 1.1 million pintails would be expected. These two species were singled out as being of special concern, because they declined more than most other waterfowl species in the PPR and have continental breeding population goals listed in the NAWMP. Table 1, represents a stepdown of population objectives from the NAWMP to the PPJV.
A recruitment rate of 0.6 was calculated as necessary to increase the mallard population from 1990 levels in the PPR to the target level 1.2 million by 2001, given present hen survival rates. The mallard was selected as an indicator species for upland-nesting ducks, because it is the best understood of the upland-nesting species. The recruitment rate objective should vary by species, depending upon survival rates and desired population growth, however, for simplicity, 0.6 was chosen as a level that would likely result in meeting the breeding population target.
The NAWMP originally recommended a PPR nesting success rate (percentage of nests hatched) of 50 percent. However, after a review of PPR nesting studies, the Waterfowl Technical Committee (WTC) of the PPJV concluded that this rate of success was unrealistic across the PPR landscape, even though it has been observed on intensively managed areas. Depending upon duckling survival and breeding effort, achieving a recruitment rate of 0.6 will require an average nest success rate of about 18 percent.
The following table reflects habitat objectives (protected, restored, enhanced) that have been provided by State PPJV coordinators for the 1987 - 1993 PPJV Accomplishment Report, and are currently identified as objectives (acres) for the PPJV in the 1994 NAWMP Update.
|Table 2. PPJV Habitat Objectives (acres), 1986 through the year 2001.|
(ACRES) FOR PPJV
|* Includes 1,000,000 acres protected by the MN Wetland Conservation Act of 1991 (regulatory).|
|NOTE:||Simply adding up the protected, restored, and enhanced categories gives a false impression of the total acres to be affected. Some restoration and enhancement acres may already be counted in the protection category.|
Stabilize or increase populations of declining wetland/grassland-associated wildlife species in the PPR, with special emphasis on non-waterfowl migratory birds.
This objective, when combined with the first objective, will ensure that conservation efforts designed to achieve waterfowl goals are not detrimental to other wetlands/grassland-associated wildlife already in decline. Whenever possible, Joint Venture implementation strategies will be designed to be beneficial to all migratory birds. In delivering habitat conservation efforts to achieve both objectives, improved natural diversity in the prairie landscape will be accomplished.
Progress toward this objective will be monitored through the Fish and Wildlife Service (Service)/National Biological Survey (NBS) Breeding Bird Survey (BBS) and through specific monitoring and research projects designed to measure response of these species to conservation efforts being implemented. A much better understanding of how wetland/grassland-associated wildlife responds to management actions is required. Particular emphasis will be placed on non-waterfowl migratory birds that have exhibited downward trends in population levels, as well as threatened and endangered species such as the piping plover.
Habitat problems for many declining wetland/grassland-associated non-waterfowl migratory birds are closely linked to those being experienced by waterfowl. Fragmentation of the prairie, loss of certain wetland types and nesting cover, intensive grazing of remnant grassland, and altered predator communities have contributed to the decline of prairie wildlife populations in general. Habitat conservation strategies for other prairie wildlife in the PPR will be very similar to those employed for waterfowl. Implementation strategies will focus on restoring prairie wetland complexes and vegetation communities, while protecting wetland and remnant native tracts. In some cases, modifications can be made to habitat programs designed to benefit waterfowl so that key elements are provided for more specialized species, thereby adding value to conservation efforts.
The Service estimates there are over 800 migratory bird species in North America, of which 225 breed in the PPR. Several grassland species have declined significantly over the past three decades, according to the BBS. Lark bunting and grasshopper sparrow declined by more than 4 percent per year, while the bobolink declined by 2.7 percent, the Baird's sparrow by 2 percent, and the dickcissel by 1.5 percent. All these species seem to respond positively to reestablished grassland in the PPR. Other analyses of these data indicate that wetland conservation actions taken to benefit waterfowl on the prairies have stabilized populations of marbled godwit and Wilson's phalarope.
Appendix C references various studies conducted to ascertain the impact of various land management practices on non-waterfowl species.