The BLM considered designating (including new areas and adjustments) four types of HMAs. These include the 2015 types, PHMA, RHMA, and GHMA, and an additional HMA called Connectivity (CHMA) to capture unique, potential migration areas, particularly in silver sage habitat. Priority habitat (PHMA) includes areas with relatively limited impacts and containing substantial and high-quality habitat. These areas have been identified as having the highest conservation value to maintaining sustainable GRSG populations or maintaining the extent of the GRSG range. Restoration Habitat (RHMA) are areas with ongoing or imminent impacts that recently (i.e., in the 21st Century) contained substantial and high-quality GRSG habitat. In general, these areas differ from other HMAs as the BLM is identifying separate management actions to emphasize restoring habitat to establish or enhance GRSG populations. General habitat (GHMA) are areas with or without ongoing or imminent impacts containing seasonal or year‐round habitat outside other HMA, including for the purpose of promoting movement and genetic diversity. Finally, Connectivity Habitat (CHMA) are areas that provide regions of connectivity important to facilitate the movement of GRSG and maintain ecological processes. While typically unoccupied or with inactive leks, this HMA boundary represents where stopover sites may exist, likely within a matrix of degraded or converted habitat or non-habitat, particularly in silver sagebrush habitats in northern Montana.

In both Alternatives 1 and 2 HMAs are the 2015 designations, as MT/Dak was not part of the 2019 plan amendments. In these alternatives two areas of the state with known GRSG habitat do not have designated HMAs because the Butte Field Office and the Upper Missouri River Breaks National Monument (UMRBNM) were not part of the 2015 planning effort. While there are no designated HMAs for Butte and UMRBNM these RMPs contain GRSG related objectives and management actions. While there are some differences between the MT EO habitat boundaries and the BLM 2015 GRSG Plan HMAs, the proportion of birds found in different habitat types remains similar. BLM PHMA and RHMA boundaries encompass 75-80% of known displaying males (similar to core areas) with the remaining 1/5 to 1/4 of the state population found in GHMA (similar to general habitat). In North and South Dakota BLM PHMA matches the core habitat identified by those states at the time, capturing the majority of breeding habitat for all known active leks.

Alternative 3 considers HMA boundary adjustments to the 2015 plans, utilizing those HMAs as a starting point. Changes account for areas of GRSG habitat or leks identified since 2015, removal of areas that are not, and highly unlikely to be, occupied in the future and state identified connectivity habitats in Montana. This alternative would consider the same management across all HMAs, (i.e., all occupied HMAs as PHMA), therefore changes are focused on refining the extent of habitat. Through the planning process the BLM identified that in North Dakota and South Dakota GRSG habitat extent has not changed since 2015 Records of Decision (RODs). In Montana the BLM added in areas of habitat mapped by MT FWP where there is evidence of use, while also removing areas designated by the BLM in 2015 but are not considered GRSG habitat by MT Fish, Wildlife, and Parks (FWP) or based on multiple lines of evidence are not GRSG habitat. In addition, habitat in Butte and UMRBNM was included as HMAs. Finally, due to the unique behavior of GRSG in silver sage habitat (in the HiLine Field Office) the BLM mapped and designated Connectivity habitat (CHMA). These areas included state connectivity habitat as well as additional areas that may also provide for GRSG movement between known populations. All changes were made by considering local knowledge, cooperating agency input, and multiple sources of information, e.g., based on the preponderance of evidence. Alternative 3 includes possible ACECs identified for analysis in this planning effort.

For Alternative 4 and 5 the outer boundaries (extent) for these alternatives remains the same as determined in Alternative 3. In addition, HMA designation do not vary between the alternatives 4 and 5. The CHMA areas identified in Alternative 3 were included in 4 and 5 as well. The criteria used to consider adjustment from prior HMA designations was to improve consistency between BLM field offices, between BLM and state delineations, and between states (including Idaho and Wyoming), while accounting for new science and on-the-ground knowledge to consider adjustments to HMA boundaries. In some instances, meeting all criteria was not possible, as aspects were in conflict (e.g., consistency between multiple entities). The BLM weighed these various inputs and utilized the preponderance of evidence to designate HMA types. Overall, the goal is that changes are supported with a sound rationale including relevant biological and/or management considerations. The types of changes made in comparison with Alternative 1 and 2 HMAs include switching between RHMA and PHMA (where different management was not needed or for consistency across boundaries), changing GHMA to PHMA (areas of regional importance and for consistency with the state core areas or across state borders), switching GHMA to CHMA or identifying new CHMA (areas where habitat remains that may be important for movement), and changing PHMA to GHMA (improved consistency with state core areas). The proportion of breeding birds in HMAs among the three states remain about the same as Alternatives 1 and 2, with around 80% of birds (breeding habitat) in PHMA in Montana, whereas all known leks are within PHMA in North and South Dakota.

Alternative 6 is the same as Alternative 5, with the exception of including possible ACECs identified for analysis in this planning effort.