More Bi-State Nest and Brood Map Area Ranked Low for Survival

STEP 1 · Two maps

Marked hens supplied locations and fates for three breeding windows

These birds are a genetically distinct population on the southwestern edge of the sage-grouse range. The study area sits between the Sierra Nevada and the Great Basin. Crews radio-marked birds in 10 subpopulations. They relocated them at least twice a week through nesting and brood rearing. A nest counted as successful if at least one chick hatched. Hens with hatched nests were checked every 10 days for up to 50 days in daylight and at night. The authors split brood rearing at day 21. They mapped use and survival separately for nesting and for each brood window and then overlaid the maps.

Withheld birds and broods tested the brood use models. The early selection model had an R2 of 0.96. The late model had an R2 of 0.62. The late brood use model predicted withheld locations less well than the early one, though the authors still rated it reasonable.

STEP 2 · Nest window

Higher ground ranked well for use and survival while the burn link rested on few nests

Nest selection rose with taller sagebrush and at higher elevations. Nest survival was higher with more shrubs, more topographic roughness, more burned area and at higher elevations. Elevation lined up on both maps. Sagebrush height and the shrub term in the survival model are different covariates.

The nest mismatch the authors named was burned ground. Only 2 percent of nests sat inside a fire perimeter, and they interpreted the moderately positive survival link with caution. Our read is that this association cannot justify burning sagebrush or calling burned ground better nesting habitat. The study did not test a burn treatment. Cheatgrass was present in the study area and uncommon. The authors call megafires rare in the Bi-State. Only 4.5 percent of burned areas had more than 10 percent annual grass cover. They describe the strongest negative fire effects as sitting in other Great Basin country shaped by megafires and invasive annual grasses. Our read keeps this burn result inside that Bi-State contrast.

STEP 3 · Early broods

Selection rose with sagebrush height while survival rose at lower shrub density

In the first 21 days broods were more likely to use taller sagebrush. Survival was higher where shrub density was lower. The results do not show that the tall-sage patches were the dense ones. Early broods selected less burned ground. Survival was higher with more burned area. The authors report that broods avoided burned areas even where modeled survival was higher. They say that pattern may partly reflect few fires on ground broods could reach.

The paper's conifer lines disagree. The early brood survival results say survival rose closer to conifer cover. A later results sentence says broods selected less burned ground closer to conifer. That sentence ties the pattern to lower survival and reports high uncertainty on the conifer effect. The discussion reports little to no evidence of a conifer effect on survival. We draw no conifer survival rule from this paper.

Birds strongly avoided even low amounts of pinyon-juniper across these reproductive stages. That avoidance weakened from nesting into brood rearing. The authors suggest predator avoidance drives selection during nesting and early brood rearing when chicks are small and flightless. That suggestion is their interpretation. This study did not count predators.

STEP 4 · Late broods

Stream measures split use from survival and the slope lines conflict

Late broods selected less ground where perennial streams were more common. Survival was higher where intermittent streams were more common. The authors flag streams as one of two moderate or strong differences between the late maps.

The other difference they name is slope, and the slope lines conflict. Detailed results say late brood selection decreased on steeper slopes. Late brood survival increased on steeper slopes. A summary sentence in the same section says selection was higher and survival was lower on steeper slopes. Our read is to leave slope out of any field rule until that conflict is resolved.

Late brood selection also rose with taller sagebrush, more herbaceous cover and higher elevations. The authors suggest forage in higher mesic places matters more in this later window, once chicks are larger and resources tighten. They add that high-elevation ground tends to hold more pinyon-juniper and can make conifers harder to avoid. Their results did not support a survival impact from that pattern.

STEP 5 · Map check

Locations show use and marked hens show fates

The authors suggest protecting ground that ranks high for both use and survival. They suggest restoration on ground with high use and low survival. The open question they name is what drives poor reproduction. They caution that a survival-only focus may not grow local distribution if birds do not select that ground first.

Our check starts with the evidence behind a ranking. Bird locations support a use map. Marked nests or broods with known fates can show loss on ground hens use. Our read is to study that loss before treating the ground as productive. Seeing hens or broods can show local use. It cannot show whether a nest hatched or a brood lasted 50 days. This study learned those fates by relocating radio-marked hens. Our check is the ranking's own documentation. Does it cite only bird locations, or also marked nests and broods with known fates, and for which years and life stage? Incidental sightings, logged without approaching or flushing birds, record where birds were seen. They cannot measure selection against available habitat, name individual hens, recover these modeled rates, or show that the place produces birds.

The paper notes that this population segment has been evaluated for Endangered Species Act listing separately from other sage-grouse. This piece is a breeding-season habitat reading for that isolated population. It states no current listing and no hunting rule. Rules vary, so check your state wildlife agency.

The authors ranked pixels and did not model travel between life stages. A low rank can flag nesting or one brood window. It does not measure year-round population growth. This paper cannot settle other sage-grouse populations.