Tacha, M.C. and T.C. Tacha. 1985. Status and distribution of sandhill cranes in Minnesota. Final report submitted to the Minnesota Department of Natural Resources. 36+ pp.
The objectives of this study are as follows: 1) Compile and review available information pertinent to the management of Sandhill Cranes in Minnesota, 2) Develop a thorough bibliography of references related to the status and management of Sandhill Cranes in Minnesota, 3) To identify requisite information not currently available for management planning and to recommend feasible, cost-effective research necessary to obtain such information, and 4) To identify various management options, based on the synthesis of information.
A comprehensive literature search during spring and summer 1995 yielded nearly 200 articles and reports pertinent to the management of Sandhill Cranes in Minnesota. "Resident" cranes are those observed in Minnesota between May 1 and August 31. Cranes observed in Minnesota before and after that time range are referred to as "unknown". The term "breeder" is applied narrowly to residents associated with a known nest or observed with young. The term "nonbreeder" applies to all cranes not meeting the breeder criteria. The term "migrants" is used without regard to resident/nonresident status and simply refers to concentrations observed during migration periods.
By 1900, once common Sandhill Cranes were described as rare in Minnesota (Swanson, 1940). In the Lake States, cranes have been protected by the Convention for Protection of Migratory Birds since 1916 (Miller, 1985). According to Henderson (1979b:2), distribution of resident Sandhill Cranes in Minnesota consisted of "two separate populations--a northwest population and an east central population." These authors believe observed changes in distribution are primarily caused by an expanding Sandhill Crane population, resulting in the pioneering of resident cranes into new areas. Non-breeding cranes may constitute nearly half of the total Minnesota population. The resident Minnesota crane population has been assigned to the eastern population of greater Sandhill Crane (Grus c. tabaida) (Littlefield, 1981; Drewien et al., 1975; Nesbitt and Williams, 1979). Within the known Sandhill Crane distribution, suitable breeding habitat can include any large, shallow, relatively open, isolated wetland adjacent to open, upland foraging areas. Non-breeders have been observed in a variety of habitats during the summer. Combinations of scare techniques and use of lure crops have met with some success in reducing waterfowl depredations, and may be worth considering if actual crane depredations in the northwest justify the expense.
Management options for Sandhill Cranes in both northwestern and east central Minnesota can be reduced to three basic strategies: 1) maintain current management practices (no active management), 2) active management to increase populations, and/or 3) decrease or redistribute populations in local areas where depredations are significant. Quantitative estimates of the resident breeding population size are the most necessary and most financially demanding research efforts needed. The second most critical need is identification of population affiliations (and associated migration routes and wintering areas) of resident cranes. The most cost-effective approach to obtaining information detailed above would be to fund a 2-3 year project that has two major complementary studies.