Recent Population Trends of Mountain Goats in the Olympic Mountains, Washington

Jenkins, Kurt J.; Happe, Patricia J.; Beirne, Katherine; Hoffman, Roger A.; Griffin, Paul C.; Baccus, William; Fieberg, John

doi:10.3955/046.086.0403

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…). Consistent with most other sightability studies (e.g., Steinhorst and Samuel , Jenkins et al ), we recorded a single data point for each GPS‐collared bison present in a given stratum at the time of flying the stratum. Thus, a bison wearing a functioning GPS collar could be classified as detected, missed, or as a duplicate observation across strata but not within a stratum.…”

Section: Methodsmentioning

confidence: 99%

Estimating ungulate abundance while accounting for multiple sources of observation error

Terletzky

Koons

2016

Wildl. Soc. Bull.

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Whether a species is rare or overabundant, accurate estimates of population abundance are essential for the development and assessment of conservation plans and management goals. Aerial surveys are commonly used to estimate population abundance and a variety of methods have been used to account for recognized biases associated with imperfect detection. Rarely addressed, however, is the possibility of recording duplicate observations and the influence of duplicate observations on estimates of abundance. Using data provided by Global Positioning System (GPS)‐collared bison (Bison bison) and helicopter survey paths conducted during 2011–2013 in the Henry Mountains, Utah, USA, we determined whether GPS‐collared bison were observed, missed, or observed multiple times. Using these data, covariates hypothesized to influence observation errors, and generalized linear models, we found the probability of detecting a GPS‐collared bison (study‐wide mean of 95%) was consistently greater for individuals in larger groups and less rugged terrain. We also found that the probability of recording a duplicate observation (study‐wide mean of 4.4%) increased with time since the prior survey observation. By incorporating both types of observation error into a modified Horvitz–Thompson estimator, more accurate estimates of bison abundance can be attained, particularly in years when animals segregate into small groups, utilize terrain that makes them difficult to see, or have ample time to move into areas not yet surveyed and be counted again. Our approach of accounting for multiple sources of observation error can easily be applied to aerial surveys for other species in other systems, and has the potential to improve the rigor of wildlife abundance estimation from aerial surveys. © 2016 The Wildlife Society.

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Section: Methodsmentioning

confidence: 99%

Estimating ungulate abundance while accounting for multiple sources of observation error

Terletzky

Koons

2016

Wildl. Soc. Bull.

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“…Greater detail on capture and handling is given in Rice et al () and Jenkins et al () for mountain goats captured by aerial darting from a helicopter ( n = 64), darting from the ground ( n = 19), and leg‐noosing with physical restraint ( n = 3) in 2002–2007. Darted animals were generally immobilized with 1.2–1.5 mg carfentanil.…”

Section: Methodsmentioning

confidence: 99%

Do capture and survey methods influence whether marked animals are representative of unmarked animals?

et al. 2015

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Radiocollared animals are frequently used to estimate detection probabilities in aerial surveys. The aircraft used to conduct these surveys may also have been used to aid in the capture of these animals, and recently captured animals may react to hearing or seeing the aircraft, changing their behavior in a way that calls into question the representativeness of estimated detection probabilities. We conducted a literature review and found 30 studies that used radiocollared animals to build sightability detection models; in !15 of these studies, the same aircraft was used to capture and survey animals. Although it is difficult to determine whether captured animals have different sighting probabilities than the rest of the target population, we used multiyear resighting data collected from moose (Alces alces) in Minnesota, elk (Cervus elaphus) in Washington, and mountain goats (Oreamnos americanus) in Washington and Alaska, to evaluate whether detection probabilities increased or decreased as a function of time since original capture. We did not detect statistically significant within-individual time trends in detection probabilities, although we could not rule out the possibility of biologically significant results because confidence intervals on effect sizes were relatively wide. The lone exception to this rule was for the cohort of radiocollared moose in Minnesota, which exhibited a slight decrease in detection probabilities over time. Differences in detection probabilities for marked and unmarked animals may not be a significant problem for sightability models, provided that the source of the variability can be captured by model covariates (e.g., heterogeneity is tied to an individual's propensity to be in heavy cover). Nonetheless, capture-related effects likely deserve greater consideration than currently afforded, and are critically important when applying simple mark-recapture abundance estimators (Lincoln-Petersen, markresight) that do not allow consideration of sighting covariates. Ó 2015 The Wildlife Society.

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“…Eight of the study areas were located within the Cascade Mountain Range; the remaining area was located within ONP (Houston et al 1994). We aggregated data originating from 7 independent investigations (Rice 2008;Jenkins et al 2011Jenkins et al , 2012Vales et al 2016;Sevigny et al 2021;Harris et al 2022) into our 9 study areas (Table S1, available in Supporting Information). In most cases, geographic aggregation was straight-forward; however, Rice (2008) monitored mountain goats in several different sites within the Cascade Mountain Range.…”

Section: Study Areamentioning

confidence: 99%

Survival of adult mountain goats in Washington: effects of season, translocation, snow, and precipitation

Harris,

Happe,

Moore

et al. 2023

J Wildl Manag

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Elucidating patterns of adult survival rates is key to understanding population dynamics of large mammals. We used data from 7 separate studies of mountain goats (Oreamnos americanus) conducted from 2002 through 2022 in western Washington, USA, to quantify survival rates in relation to key biotic and abiotic factors using known fate models implemented in program MARK. We monitored 324 (206 females, 118 males) radio‐marked mountain goats for 178,339 days. A substantial number of mountain goats in our sample (n = 217) had been translocated from the Olympic Peninsula to the Cascade Mountains on Washington's mainland, providing an added opportunity to examine translocation effects. We adopted a sequential modeling approach, first building a set of models to examine fundamental survival patterns by age, sex, season, study area, and translocated status. We used variables retained from the top model in a second set to investigate relationships between annual survival and local weather covariates hypothesized by previous studies to influence mountain goat behavior, habitat selection, and vital rates. Survival among adult females in spring was slightly lower than other sex and age categories, but seasonal patterns were otherwise not evident. There were significant negative relationships between survival and winter snow depth, an index of the previous year's drought, and mean daily temperature during the previous May, and a positive relationship with previous year's precipitation. Weather effects were similar among resident and translocated animals. By the end of the study period, weather effects had evidently contributed to reductions in mountain goat survival to a level low enough that population stability was unlikely. Because the frequency of droughts and warm spring temperatures are expected to increase with climate change, mountain goat populations in Washington will likely be increasingly challenged as the atmosphere warms.

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Recent Population Trends of Mountain Goats in the Olympic Mountains, Washington

Cited by 3 publications

References 19 publications

Estimating ungulate abundance while accounting for multiple sources of observation error

Estimating ungulate abundance while accounting for multiple sources of observation error

Do capture and survey methods influence whether marked animals are representative of unmarked animals?

Survival of adult mountain goats in Washington: effects of season, translocation, snow, and precipitation

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