Status of 2023 Oregon Greater Sage-Grouse Adaptive Management Triggers

Purpose

This information bulletin (IB) transmits the results of the Oregon Greater Sage-grouse (sage-grouse) adaptive management thresholds and triggers evaluation for calendar year 2023. This IB summarizes the thresholds and where they were exceeded, which adaptive management triggers were activated or reversed, the required responses where a hard trigger was activated, and a summary of the causal factor analysis process and outcomes.

Background

The Oregon Department of Fish and Wildlife (ODFW) organized its sage-grouse Core Areas into 20 rational groups called Oregon Priority Areas for Conservation (PAC). Oregon PACs encompass all Bureau of Land Management (BLM) Priority Habitat Management Areas (PHMA) and contain the most productive habitat for approximately 90 percent of the state’s breeding populations of sage-grouse within 38 percent of the species’ current range statewide. These areas have the highest conservation value to maintaining sustainable sage-grouse populations in Oregon. The Adaptive Management Strategy in Appendix J of the BLM’s Oregon Greater Sage-Grouse Approved Resource Management Plan (ARMPA) identifies hard and soft thresholds (triggers) for habitat and populations within these PACs. Exceeding (tripping) a hard threshold triggers BLM to implement immediate and more restrictive plan-level actions to address sage-grouse conservation objectives. Soft triggers indicate that BLM may need to implement management changes at the project level to reduce the likelihood of further declines leading to a hard trigger.

The Adaptive Management Strategy, revised in 2020, outlines the process the BLM Oregon/Washington (OR/WA) used in cooperation with the ODFW and the U.S. Fish and Wildlife Service (FWS) to determine the annual status of sage-grouse adaptive management triggers. The BLM transmitted the population trigger calculations to ODFW and FWS on October 30, 2023. With this IB, the required hard trigger responses listed on page J-8 of the ARMPA go into effect in the seven PACs displayed in the attached map. These responses remain in effect until either a plan amendment makes a change to the ARMPA or the BLM’s annual review of the relevant conditions listed in the Adaptive Management Strategy indicate the trigger has reversed.

Habitat Trigger

Habitat triggers are calculated from the proportion of all capable habitat acres within a PAC that are in existing (current) habitat. Capable habitat includes areas that either currently support vegetation cover appropriate for sage-grouse use (i.e., ≥5 percent cover of sagebrush species and <5 percent tree cover) or are predicted to support these vegetation conditions with treatments and/or natural plant succession. The BLM used two datasets from the Integrated Landscape Assessment Project developed by the Institute for Natural Resources to identify capable habitat and current habitat. Oregon PACs are mostly (89 to 99 percent) capable habitat. Current habitat that has burned with moderate to high soil burn severity classes, based on Burned Area Reflectance Classification (BARC) maps, is considered habitat loss. Unburned to low fire severity classes represent islands of sagebrush within the fire perimeter that are not considered habitat loss.

Current habitat in 2023 was below the soft trigger threshold (i.e., <65 percent current habitat) in the Cow Lakes PAC and Trout Creeks PAC (Table 1). Both PACs were below the habitat threshold prior to the 2015 ARMPA. The historic Vale Seeding Project and multiple wildfires removed sagebrush from large sections of the Cow Lakes PAC. Seventy-two percent of the Trout Creeks PAC has burned at least once since 1975, with many acres burned multiple times. Five additional PACs with 65 to 70 percent current habitat also are identified in Table 1. While these PACs have not tripped a habitat trigger, they are at risk of doing so with one large wildfire event.

Table 1. Oregon PACs that have tripped (<65 percent current habitat) or are close to tripping (65 to 70 percent current habitat) a habitat trigger in 2023.

¹Habitat burned with moderate or high severity fire.
²Acres are project footprints. Records are from VMAP and OR/WA Treatments, while previous years were only from the latter source.
³Cow Lakes PAC also tripped a hard population trigger.

There were fires in Folly Farm-Saddle Butte, Cow Lakes, Baker, and Bully Creek PACs totaling approximately 203 acres. The largest of these fires burned approximately 114 acres inside the Folly Farm-Saddle Butte PAC. Only the Baker PAC lost sage-grouse habitat to moderate or high intensity fire. The Medical Springs and Spring Creek fires burned approximately 86 acres resulting in 3 acres of habitat lost.

The BLM implemented vegetation treatments in 2023 on 148,637 acres of BLM-administered lands within the seven PACs identified in Table 1. These acres are project footprints that in most cases include multiple treatments on the same site (e.g., cut, pile, and burn juniper). Additional treatments have occurred on private lands. Treatments have included juniper removal, seeding, sagebrush planting, biological agents, and chemical spraying (herbicide) of invasive annual grasses. Treatment acres can be added to current habitat acres only after a BLM field office has verified the treated area currently supports ≥5 percent cover of sagebrush species and <5 percent tree cover.

Population Trigger

BLM sage-grouse population triggers are based on population estimates generated from maximum counts of males at each lek complex (closely allied leks within 1 mile of each other) using a stratified random estimator. Annually, ODFW provides BLM with an estimate of the number of males in the 16 PACs containing an adequate number of leks to provide a reliable population estimate (Table 2). BLM uses these estimates to determine whether a PAC has tripped a soft or hard population threshold. BLM established population thresholds in the 2015 ARMPA based on year-to-year variation of the mean population estimate for the previous 16 to 20 years. In 2020, ODFW re-calculated population trends for the same years, and BLM reset the population trigger thresholds in accordance with direction contained in the Oregon BLM Adaptive Management Strategy to update the thresholds five years after issuing the ARMPA.

Sage-grouse population estimates based on counts of males attending leks contain multiple assumptions regarding lek formation and extinction rates. Lek counts are an index of population size, and the actual number of sage-grouse in each PAC remains unknown. Population trends typically vary more at the scale of individual PACs than at the state-wide level. The BLM and ODFW have high confidence in the accuracy of the population estimates due to the high proportion of known leks and lek complexes surveyed each year (-48.4 and 44.8 percent respectively in 2023) and consistency in monitoring methods applied over the previous 24+ years. ODFW recommends caution when interpreting the 2023 population estimates due to the abnormal snowpack in sage-grouse breeding habitat during the lekking season and the low survey effort compared to the previous 8 years.

The sage-grouse population in Oregon declined 11.4 percent in 2023. Oregon’s annual population estimates have followed a 6- to 7-year cycle, with the population decline in 2023 following 3 years of population increases from 2020–2022, which followed 3 years of population decline from 2017–2019. Seven of the 10 PACs that tripped population triggers in 2023 (Table 2) tripped the same population triggers in 2022. The Paulina/12-Mile/Misery Flat PAC moved from tripping a soft trigger in 2022 to tripping a hard trigger in 2023. Drewsey and Soldier Creek PACs had not tripped a trigger in 2022.

Table 2. Status of population triggers in Oregon PACs in 2023.

Population trends recorded in the 10 PACs that tripped triggers in 2023 are described below. Oregon PACs are located within mid-scale areas (shown in parentheses for each PAC) identified by the BLM and ODFW for use in the sage-grouse Habitat Assessment Framework and for allocating annual funding to habitat conservation and restoration projects in high priority areas of the state.

Baker PAC (Baker) population decreased 5.7 percent in 2023, although this negative trend was partly due to an error ODFW found in the 2019 and 2020 data. Male attendance at lek complexes has declined 87.2 percent since the last population peak in 2003. While ODFW believes the observed population decrease is likely accurate, it feels the magnitude of annual population trends is likely inflated due to issues with the population analysis methodology. This population appears to have stabilized over the past 5–8 years This small population is particularly vulnerable due to its geographic isolation from all other sage-grouse populations.

Beatys PAC (Warner-Meinzer) first tripped a soft population trigger in 2019 when male lek attendance declined 50 percent from the previous year. Population growth in 2020 and 2021 was not enough to prevent the 5-year moving average population from sinking below the soft trigger threshold. The population declined 19.9 and 6.5 percent in 2022 and 2023, respectively. ODFW contracted helicopter lek searches in the PAC (including Hart Mountain National Antelope Refuge) and surrounding low-density sage-grouse habitat in 2023. Over 20 locations where sage-grouse had not previously been seen displaying were documented. Abnormally high snowpack throughout most sage-grouse lekking areas in the PAC during the survey period may have influenced breeding behavior. The potential new lek locations will need to be checked and confirmed on the ground during the 2024 sage-grouse breeding season.

Brothers-North Wagontire PAC (Central Oregon) first tripped the soft population trigger in 2016 and tripped the hard population trigger in 2018. Following a 60.8 percent increase in 2020, the population declined 27.8 percent in 2021, was almost flat in 2022 and increased 19.6 percent in 2023. The 5-year population trend is poised to rise above the hard trigger threshold.

Cow Lakes PAC (Owyhee River) population has been in decline since the 2015 Soda Fire burned leks and important seasonal habitat in Oregon and Idaho. This population was below the soft trigger threshold in 2015 and despite a moderate increase in 2021, the population dropped below the hard trigger threshold. This downward trend continued in 2023 with a 28.9 percent decline from the 2022 population estimate.

Drewsey PAC (Malheur River) last tripped a soft population trigger in 2019 due to a >40 percent decline in a single year. While the population estimate increased during the following three years, the decline in 2023 was sufficient to pull the estimate below the soft trigger threshold. ODFW recommends caution when interpreting the 2023 population estimates due to the abnormal snowpack in most sage-grouse breeding habitat during the 2023 lekking season, and the low survey effort compared to the previous 8 years.

Dry Valley-Jack Mountain PAC (Warner-Meinzer) population estimate has declined 84 percent since the Miller Homestead Fire burned over one-third of the sagebrush habitat and four lek complexes in 2012. The population declined below the soft trigger threshold in 2016, tripped the hard trigger in 2017, and reached a population nadir of 49 males in 2019 relative to the peak in 2012 of 582 males. After 3 consecutive years of growth during 2020-2022, this population declined slightly (1.1 percent) in 2023 and remains firmly below the hard trigger threshold.

Paulina-12 Mile-Misery Flat PAC (Central Oregon), often referred to simply as the Paulina PAC, first tripped the soft population trigger in 2016. In 2017, the 5-year average population estimate increased above the soft trigger threshold despite the annual estimate dropping 6.9 percent. The annual estimate fell 8.4 percent in 2023, pulling the 5-year mean population estimate below the hard trigger threshold for the first time since the adaptive management strategy began in 2015.

Picture Rock PAC (Warner-Meinzer) has tripped the hard population trigger every year since 2017. The 2023 annual population estimate increased 33.3 percent above the 2022 annual estimate (9 males) and equals the 2015 estimate of 12 males.

Soldier Creek PAC (Owyhee River) tripped a soft population trigger in 2020 due to >40 percent decline in a single year. The annual estimate increased in 2021, thereby reversing the soft trigger. With further population grown in 2022, the population appeared to be stable. However, a 48.2 percent decrease in 2023 has dragged the 5-year mean population estimate below the soft trigger threshold for the first time since 2020. This PAC’s annual population estimate has declined 60.8 percent since 2015.

Warners PAC (Warner-Meinzer) population estimate has increased 4.2 percent since 2015. The population peaked in 2016 and tripped the hard trigger in 2021. Annual population growth in 2022 (24.9 percent) and 2023 (21.9 percent) reversed the downward population trend. The 2023 annual estimate is greater than the 2015 annual estimate. If the annual estimate continues to increase in 2024, this PAC will reverse its hard trigger.

Hard Trigger Responses

Responses to triggers that involve management changes or more restrictive plan level actions to address declines in habitat or population are outlined in the Adaptive Management Strategy in Appendix J of the ARMPA. All required hard trigger responses remain in place until the habitat or population trigger, whichever was tripped, rises above the trigger threshold. Exceptions to the hard trigger response can be allowed when the cause for a hard trigger is wildfire or insect outbreak, the disturbance cap has not been reached, and the BLM authorized project would have no direct or indirect impact on the sage-grouse population or habitat.

Causal Factor Analysis and Annual Review

When an adaptive management trigger is tripped, the BLM conducts an analysis of existing conditions and trends in the affected PAC to identify and address the apparent cause(s) for decline. Attachment 2 provides a brief overview of the Causal Factor Analysis (CFA) procedures and results. Causal factor reports have been completed for all Oregon PACs that tripped a trigger in 2023.

BLM field offices review their CFA report(s) annually to update them with current information on population trend, fire occurrence, drought conditions, habitat changes, vegetation treatments, and any other relevant information, management activities, and BLM authorizations implemented within the PAC. This information is recorded on the CFA Annual Review Form, signed by the District Manager or Field Manager, and uploaded to the OR/WA GRSG SharePoint in the Adaptive Management folder. If the BLM district determines the threats it analyzed in the CFA have not substantially changed, regardless of change in trigger status, then the CFA does not need to be revised. Annual reviews are due by the end of each calendar year.