U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2016–1185

Prepared in cooperation with the National Park Service

Mountain Goat Abundance and Population Trends in the 

Olympic Mountains, Northwestern Washington, 2016
Cover: Photograph showing three mountain goats observed during aerial surveys in Olympic National Park, Washington, July 2016.

 Photograph by Patricia J. Happe, National Park Service. 

 
U.S. Department of the Interior

U.S. Geological Survey

Mountain Goat Abundance and Population Trends in the 

Olympic Mountains, Northwestern Washington, 2016

By Kurt J. Jenkins, Patricia J. Happe, Katherine F. Beirne, and William T. Baccus 

Prepared in cooperation with the National Park Service

Open-File Report 2016–1185
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

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Suggested citation:

Jenkins, K.J., Happe, P.J., Beime, K.F., and Baccus, W.T., 2016, Mountain goat abundance and population trends 

in the Olympic Mountains, northwestern Washington, 2016 : U.S. Geological Survey Open-File Report 2016–1185, 

21 p., https://doi.org/10.3133/ofr20161185. 

ISSN 2331-1258 (online)
iii

Contents

Executive Summary.................................................................................................................................................... 1

Introduction................................................................................................................................................................. 2

Study Area and Methods ............................................................................................................................................ 3

Sampling................................................................................................................................................................. 3

Aerial Surveys......................................................................................................................................................... 7

Population Abundance............................................................................................................................................ 8

Population Trends................................................................................................................................................... 9

Results........................................................................................................................................................................ 9

Aerial Surveys......................................................................................................................................................... 9

Population Abundance.......................................................................................................................................... 11

Population Trends................................................................................................................................................. 11

Discussion ................................................................................................................................................................ 12

Acknowledgments..................................................................................................................................................... 13

References Cited...................................................................................................................................................... 14

Appendix 1. Survey Flight Characteristics during Aerial Mountain Goat Surveys, Olympic Mountains, 

Northwestern Washington, 2016............................................................................................................................... 16

Appendix 2. Survey Characteristics and Environmental Conditions Measured at the Beginning of Each Unit 

Surveyed in the Olympic Mountains, Northwestern Washington, 2016..................................................................... 17

Appendix 3. Raw Counts of Mountain Goats by Survey Unit, Olympic Mountains, 

Northwestern Washington, 2016............................................................................................................................... 20

Figures

Figure 1. Map showing location of study area in Olympic National Park and Olympic National Forest, 

northwestern Washington. ......................................................................................................................................... 4

Figure 2. Map showing sampling strata, units surveyed, and number of mountain goats counted during 

mountain goat surveys in the Olympic Mountains, northwestern Washington, July 13–24, 2016 .............................. 5

Figure 3. Graph showing trends in the minimum population index and estimated population abundance 

(±standard error) of mountain goats in the Olympic Mountains, northwestern Washington, 1983–2016................. 12

Tables

Table 1. Mountain goat survey characteristics and raw counts of mountain goats in eight total 

count areas, and in high-, medium-, and low-density strata, Olympic Mountains, northwestern

Washington, July 13–24, 2016................................................................................................................................ 10

Table 2. Population estimates of mountain goats, associated components of variance, standard errors,

and 95-percent confidence intervals in the Olympic Mountains survey area, northwestern Washington, 

2004–2016............................................................................................................................................................... 10
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Flight speed

mile per hour (mi/h) 1.609 kilometer per hour (km/h)

SI to Inch/Pound

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

hectare (ha) 2.471 acre 

square kilometer (km2) 0.3861 square mile (mi2) 

Flight speed

kilometer per hour (km/h) 0.6214 mile per hour (mi/h)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32. 

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.
1 

Mountain Goat Abundance and Population Trends in the

Olympic Mountains, Northwestern Washington, 2016 

By Kurt J. Jenkins1, Patricia J. Happe2, Katherine F. Beirne2, and William T. Baccus2

Executive Summary 

We estimated abundance and trends of non-native mountain goats (Oreamnos americanus) in the 

Olympic Mountains of northwestern Washington, based on aerial surveys conducted during July 13–24, 

2016. The surveys produced the seventh population estimate since the first formal aerial surveys were 

conducted in 1983. This was the second population estimate since we adjusted survey area boundaries 

and adopted new estimation procedures in 2011. Before 2011, surveys encompassed all areas free of 

glacial ice at elevations above 1,520 meters (m), but in 2011 we expanded survey unit boundaries to 

include suitable mountain goat habitats at elevations between 1,425 and 1,520 m. In 2011, we also 

began applying a sightability correction model allowing us to estimate undercounting bias associated 

with aerial surveys and to adjust survey results accordingly. The 2016 surveys were carried out by 

National Park Service (NPS) personnel in Olympic National Park and by Washington Department of 

Fish and Wildlife (WDFW) biologists in Olympic National Forest and in the southeastern part of 

Olympic National Park. We surveyed a total of 59 survey units, comprising 55 percent of the 60,218-

hectare survey area. We estimated a mountain goat population of 623 ±43 (standard error, SE). Based 

on this level of estimation uncertainty, the 95-percent confidence interval ranged from 561 to 741 

mountain goats at the time of the survey. 

We examined the rate of increase of the mountain goat population by comparing the current 

population estimate to previous estimates from 2004 and 2011. Because aerial survey boundaries 

changed between 2004 and 2016, we recomputed population estimates for 2011 and 2016 surveys based 

on the revised survey boundaries as well as the previously defined boundaries so that estimates were 

directly comparable across years. Additionally, because the Mount Washington survey unit was not 

surveyed in 2011, we used results from an independent survey of the Mount Washington unit conducted 

by WDFW biologists in 2012 and combined it with the 2011 survey results to produce a complete 

survey conducted over 2 years. The revised estimates of mountain goat abundance occurring at 

elevations above 1,520 m were 230 ±19 (SE) in 2004, 350 ±41 (SE) in 2011, and 584 ±39 (SE) in 2016. 

The difference between the overall 2016 population estimate (623 ±43 [SE]) and the smaller estimate

(584 ±39 [SE]) reflected the number of mountain goats counted in the expanded survey areas added in 

2011. Based on comparisons within the standardized survey boundary, the mountain goat population 

1

U.S. Geological Survey. 2

National Park Service.
2 

in the Olympic Mountains increased at an average finite rate of 6 percent annually from 2004 to 2011, 

11 percent annually from 2011 to 2016, and 8 percent annually over the combined period. We caution 

that the population may have been underestimated in 2011 because of record heavy snows persisting 

into the survey season. Therefore, the rate of population increase from 2011 and 2016 may be 

overestimated. The rate of increase measured over the combined period (2004–16) may be more 

representative of the recent population growth. We conclude that the abundance of mountain goats has 

increased for more than a decade, and if the recent average rate of population growth were sustained, the 

population would increase by 45 percent over the next 5 years. 

Introduction 

Mountain goats were introduced in the Olympic Mountains of Washington during the 1920s 

prior to the establishment of Olympic National Park (Houston, Schreiner, and others, 1994). Over the 

next several decades, the mountain goat population grew and expanded throughout the Olympic 

Mountains, leading to management concerns by the mid-1970s about the potential effects of 

overabundant mountain goats on soil erosion and endemic plants in high-elevation plant communities 

(National Park Service, 1995). In 1983, the National Park Service (NPS) conducted the first aerial 

survey to estimate mountain goat population size throughout the Olympic Mountains, generating an 

estimate of 1,175 ±171 (standard error [SE]) mountain goats (Houston and others, 1986). Other 

localized ground and aerial surveys conducted prior to 1983 did not result in complete population 

estimates (Houston, Schreiner, and others, 1994). 

During the early 1980s, the NPS translocated mountain goats from Olympic National Park to 

other ranges throughout several Western States to reduce the population (Houston, Schreiner, and 

others, 1991). During 1981–89, 407 goats were captured by the NPS and translocated (Houston, 

Hoffman, and others, 1994, p. 195). An additional 119 mountain goats were legally harvested during 

sport hunting seasons outside the park and 3 known mountain goats were illegally harvested in the park 

during 1983–97. The aerial capture and translocation program was halted in 1990 because of human 

safety concerns associated with aerial capture operations (Houston, Hoffman, and others, 1994). No 

mountain goats have been translocated from the Olympic Mountains since 1990. Outside the park, 

mountain goats were not legally harvested between 1997 and 2013. State and Tribal hunting resumed in 

2014; three goats were legally harvested between 2014 and July 2016 (R. Harris, Washington 

Department of Fish and Wildlife, written commun., 2016). 

Beginning with the first comprehensive survey conducted in 1983, the mountain goat population 

has been estimated in the Olympic Mountains every 3–7 years to assess population status and responses 

to past management actions. The second survey, conducted in July 1990 following the cessation of the 

NPS capture and translocation program, produced an estimate of 389 ±106 (SE) goats (Houston, 

Moorhead, and others, 1991). Subsequent surveys were conducted in 1994, 1997, 2004, and 2011 

during a period in which no goats were translocated by NPS managers. In this report, we present results 

from a 2016 survey, which was the seventh survey conducted since 1983, and estimate patterns of 

population growth since 2004. 
3 

Study Area and Methods

The survey encompassed high-elevation mountain goat habitat throughout the Olympic 

Mountains, of which about 87 percent is in Olympic National Park, and 13 percent is in the adjoining 

Olympic National Forest (fig. 1). The Olympic Mountains rise abruptly from the coastal plains and 

foothills of the Olympic Peninsula, culminating in Mount Olympus, the highest peak at an elevation of

2,430 m, and 37 other major peaks at elevations exceeding 2,130 m, all within about 50 km of the 

Pacific Ocean, Strait of Juan de Fuca or Puget Sound. The Olympic Mountains are noted for steep 

gradients in elevation, vegetation, and precipitation within a context of highly convoluted topography 

and landforms (Tabor, 1987; Henderson and others, 1989). 

The western slopes of the Olympic Mountains, which bear the brunt of the prevailing Pacific 

storms, have the wettest climate in the conterminous United States, generating highly variable snow 

conditions from year to year. During 2016, snow water equivalent (SWE) measured on April 1 was 108 

percent of the 30-year normal (1981–2010). A much warmer than normal spring resulted in a rapid 

warming and decreasing snowpack. By May 1, the snowpack at measurement sites ranged from 15 to 94 

percent of normal depending on aspect. The snow melt-out date at a snowpack reference site (Waterhole 

SNOTEL, Hurricane Ridge) was 21 days earlier than average. The result was that most steep terrain was 

largely free of snow in July when the survey was conducted. These conditions contrasted sharply with 

snow conditions during the previous mountain goat survey (2011), when SWE was about 167 percent of 

the 30-year normal (1971–2000) on April 1, 225 percent of normal on May 1, and the documented 

melt-out date was 30 days later than average. 

Sampling

The sampling frame encompassed 60,218 ha comprising all lands free of glacial ice at elevations 

above 1,520 m (5,000 ft) as well as areas of suitable mountain goat habitat at elevations between 1,425 

and 1,520 m (fig. 2). We defined suitable habitat as areas where escape terrain comprised at least 50

percent of the elevational band between 1,425 and 1,520 m. We defined escape terrain as any area less 

than 111 m from any 25×25-m (0.0625 ha) raster cell classified as rock and with slope greater than 33

percent (Olympic National Park Geographic Information System; Pacific Meridian Resources, 1996). 

We selected the 111-m threshold because 90 percent of all locations of 11 Global Positioning System 

(GPS)-collared mountain goats that we tracked during 2005–08 (Jenkins and others, 2011) were within 

111 m from escape cover when they were at elevations below 1,520 during the July sampling window. 

The 50-percent classification was subjectively selected based on cost and logistical considerations to 

minimize survey effort over relatively large areas of low-quality habitats. With two exceptions, the 2016 

sampling frame was the same frame as that used in 2011 (Jenkins and others, 2012). The exceptions 

were a minor adjustment to the Klahhane survey unit and the inclusion of the Mount Washington survey 

unit in 2016, which was excluded in 2011 for logistical reasons. 
4 

Figure 1. Map showing location of study area in Olympic National Park and Olympic National Forest, northwestern 

Washington. 
5 

Figure 2. Map showing sampling strata, units surveyed, and number of mountain goats counted during mountain goat surveys in the Olympic 

Mountains, northwestern Washington, July 13–24, 2016. Total counts and number of kids (young of the year) are presented in appendix 3.
6 

The sampling frame comprised a total of 109 individual sampling units (fig. 2). Sampling units 

were selected for the survey based on special management considerations and stratified random 

sampling methods (Cochran, 1977). As in years past, we assigned each of the survey units to one of four 

survey strata prior to the surveys. These strata included total count areas (TCAs), and low-density, 

medium-density, and high-density strata. Total count areas were areas of special management interest, 

all of which were surveyed. Survey units other than TCAs were assigned to mountain goat density strata 

based on results of past mountain goat surveys, recent observations of park staff, and visitor reports. 

With the exception of the TCAs, which were more variable in size, high-, medium- and low-density 

units ranged in size from 220 to 712 ha. After allotting survey time for all TCA units, we allocated the 

remaining survey effort among high-, medium-, and low-density strata using standard optimal allocation 

methods (Cochran, 1977) based on sampling variances reported within each stratum in 2011 (Jenkins 

and others, 2012). The strata were defined as follows: 

I. Total Count Areas (TCAs): We identified eight TCAs that were surveyed in their 

entirety. Four TCAs were of particular interest to the NPS because they have been 

included in every survey since 1990. These include survey units on Klahhane Ridge, 

Mount Olympus, Mount Carrie, and Chimney/Chrystal Peaks (fig. 2). Four additional 

TCAs were in the Olympic National Forest where hunting seasons are managed by 

WDFW. Collectively, these eight survey units comprised a total of 8,232 ha or about 14 

percent of the sampling frame. 

II. Known or suspected high-density areas: Units were assigned to this stratum if we 

expected to find 10 or more mountain goats per unit based on previous surveys and field 

observations. We assigned 12 survey units in the high-density stratum, encompassing 

5,534 ha and about 9 percent of the sampling frame (fig. 2). We surveyed all units in the 

high-density stratum.

III. Known or suspected medium-density areas: Units were assigned to this stratum if we 

expected 1–9 mountain goats inhabiting the survey unit. The medium-density stratum 

consisted of 42 survey units comprising 21,966 ha (about 36 percent of the sampling 

frame) (fig. 2). We randomly selected 29 survey units for survey in this stratum. 

IV. Known or suspected low-density areas: Units were assigned to this stratum if we 

expected no mountain goats. The low-density stratum consisted of 47 survey units 

comprising 24,486 ha or about 41 percent of the sampling frame (fig. 2). We randomly 

selected 10 survey units for survey in this stratum. 
7 

Aerial Surveys

Aerial survey procedures were similar to those used in previous surveys (Houston and others, 

1986; Houston, Moorhead, and others, 1991; Happe and others, 2005; Rice and others, 2009). We 

surveyed during mid- to late July, targeting the seasonal window after mountain goats have moved to 

higher elevations for summer (Rice, 2008; Jenkins and others, 2011), but before hot mid-summer 

temperatures present operational difficulties for flying at high elevations. Most surveys were conducted 

between dawn and about 10:30 a.m. PDT by a pilot and three-person crew aboard a Bell 206 B3

helicopter. The pilot’s primary responsibility was to safely fly the aircraft, but the pilot also reported 

observations. We counted mountain goats in the selected survey units by flying multiple contours about 

100 m from the terrain (that is, above flat terrain or horizontally away from vertical terrain) at elevations 

vertically spaced 90–150 m apart. Flight speed was maintained between 56 and 72 km/h (35 and 45 

mi/h). Low elevations of each unit were flown first and then the helicopter progressively worked 

upslope until the entire unit was searched. The implicit assumption is that whereas some mountain goats 

may have been missed because of non-detection, 100 percent of each survey unit was effectively 

searched. We used a GPS unit aboard the helicopter during all surveys to assist with navigation, to map 

flight paths, and to record the approximate locations of mountain goats and other wildlife seen during 

the surveys. 

We recorded conditions related to each helicopter flight, survey unit, and group of mountain 

goats observed. For each flight, we recorded the names of crew members and various flight descriptors 

(times and locations of takeoffs and landings). We recorded times at the start and end of each unit 

surveyed and several environmental conditions, including cloud cover, wind strength, precipitation

level, and temperature. Upon observing a group of mountain goats, observers recorded the total number 

of mountain goats, number of young of the year (kids), and the following covariates: (1) the percentage 

of vegetation cover capable of obscuring a mountain goat within a 10-m buffer around the group (0, 1–

25, 26–50, 51–75, or 76–100 percent), and (2) whether terrain obstruction was present within a 10-m 

buffer around the group at the moment it was first observed. We defined terrain obstruction as any 

landform capable of obscuring a mountain goat from the air. The group size, vegetation cover, and 

terrain obstruction covariates were used to estimate group-specific detection probabilities for bias 

correction (Rice and others, 2009). 

We also recorded whether each observed group was in the survey area at elevations below 1,520 

m and whether the group was below, level with, or above the helicopter flight line. These last two pieces 

of information were recorded so that we could estimate population abundance for sampling frames 

defined for the 2011 and 2016 surveys (that is, including suitable habitat at elevations between 1,425 

and 1,520 m) and for the more restricted sampling frame used prior to 2011 (that is, lands at elevations 

above 1,520 m). 
8 

Population Abundance

We estimated mountain goat abundance using the sightability modeling approach developed by 

Samuel and others (1987) and Steinhorst and Samuel (1989). This approach combines counts of 

animals, or groups of animals, in a set of randomly sampled survey units with a model for their 

probability of detection. For a stratified random sample of survey units, the estimate of population size 

(τ̂) is given by: 

τ̂= ∑ ∑ ∑ �

Nh

nh

θ�

h,i,jYh,i,j� (1) 

where the sums are over strata (h), sampled survey units (i), and observed groups (j); nh and Nh are, 

respectively, the number of stratum h plots in the sample and in the population; the θ�’s are estimated 

sightability correction factors associated with each observed group (that is, the inverse of each group’s 

detection probability); and Yh,i,j gives the number of animals in the j

th observed group (in the ith survey 

unit in stratum h).

We estimated sightability correction factors for each observed group using model-averaged 

regression coefficients and their unconditional variance covariance matrix from Rice and others (2009), 

along with formulas from Steinhorst and Samuel (1989). Specifically, Rice and others (2009) used 

sighting data from 205 sightability trials to model the probability of detection for each mountain goat 

group (j), Pdetect j , , as a function of group size (GroupSize,j), percent vegetative cover (%Veg,j), and 

terrain obstruction (Terrain).

( )

( )

( )

( )

 ́

1 2 3 4

 ́ 1 2 3 4

* , * , %,

* , * , *% , 1 1

j

j

GroupSize j Terrain j Veg j x

detect, j GroupSize j Terrain j Veg j x

e e P

e e

β +β +β +β β

β +β +β +β β = = + +

 (2)

The estimated regression coefficients (β�; Rice and others, 2009, p. 474) and their estimated 

unconditional variance/covariance matrix, Σ� (Rice and others, 2009, p. 474), were then used to estimate 

the sightability correction factors using the following equation from Steinhorst and Samuel (1989): 

θ�

h,i,j = 1 + e(−xj

′β� − xjΣ�xj

′

2 ) (3)

Three random processes create uncertainty in the estimated abundance (τ̂): (1) the random 

sampling of survey units; (2) random detection (and failed detection) of independent groups in surveyed 

units; and (3) variation in estimation of parameters used to model sightability. Wong (1996) developed 

consistent (asymptotically unbiased) estimators of each of these variance components. We estimated τ̂

based on the Steinhorst and Samuel (1989) estimator (eq. 1), and Var(τ̂) using equations from Wong 

(1996) as applied in R SightabilityModel package (R Development Core Team, 2011; Fieberg, 2012).

To place the 2004 to 2016 population estimates in historical context, we computed minimum 

population indices from all surveys conducted from 1983 to 2016. Minimum population indices were 

based on raw counts of mountain goats without any adjustment for aerial detection biases. To maintain 

consistency among years, we computed population indices based on survey area boundaries used prior 

to 2011. We computed population indices based on stratified random sampling computational methods 

described by Norton-Griffiths (1978) and used by Houston and others (1986) and Houston, Moorhead, 

and others, 1991). Standard errors of the minimum population indices account for sampling variability 

only, in contrast to standard errors of the population estimates, which account for sampling variation, 

random detection, and sightability model estimation. Because indices do not explicitly account for 

animals present but not seen during surveys, any comparison of indices implicitly assumes that 

sightability of mountain goats remained constant between surveys.
9 

Population Trends

We computed population trends and rates of population increase from surveys conducted in 

2004, 2011, and 2016. The 2004 estimate was derived retroactively by applying the detection bias 

model developed in subsequent years (Rice and others, 2009). Because we adjusted survey boundaries 

between the 2004 and 2011 surveys, we estimated population growth based on consistent survey 

boundaries used prior to 2011. That is, all observations of mountain goats from the new survey areas 

added in 2011 (elevations between 1,425 and 1,520 m) were omitted from the 2011 and 2016 datasets. 

Because we did not conduct surveys in the Mount Washington survey unit in 2011, we also substituted 

survey results for that unit from a survey conducted by WDFW partners in 2012. We recognize that 

there may have been some population growth in the Mount Washington unit between 2011 and 2012 or 

movement in or out of the unit in the intervening period, but we concluded that adding these data 

provided a more representative estimate for 2011 and a more valid comparison of population trend 

across years. We estimated the instantaneous rate of exponential population growth (r) and the average 

finite rate of growth (λ=er

) necessary to cause the observed changes in estimated abundance from 2004 

to 2016, based on the difference of the log-transformed abundance estimates (Caughley, 1977, p. 51). 

Because we used the same sightability model to estimate abundance of mountain goats in 2004, 2011, 

and 2016, we accounted for covariance between years by estimating variance of the population growth 

rate using the R SightabilityModel package (Fieberg, 2012). We used a two-tailed z-test to determine 

whether or not two estimates of abundance differed statistically from a null hypothesis of zero change 

(Thompson and others, 1998).

Results

Aerial Surveys

Mountain goats were surveyed during six mornings from July 13 to July 24, 2016, in 59 survey 

units totaling 33,391 ha (table 1). This sampling effort was roughly 40 percent greater than the area 

surveyed in either 2004 or 2011 (39–41 survey units comprising 23,458–24,524 ha were surveyed in the 

previous two surveys; Happe and others, 2005; Jenkins and others, 2012). A total of 13 flights were 

conducted by NPS and 2 flights were conducted by WDFW personnel (appendix 1). Total flight time 

was about 31 hours and 47 minutes. NPS flights, including travel between survey units and fueling 

locations, totaled about 26 hours and 17 minutes , and WDFW flights totaled another 5 hours and 30 

minutes. On several days, cloud cover interfered with survey efforts. We discontinued surveys in five 

survey units because of deteriorating weather. All five count units were resurveyed at a later date 

(appendix 2). A total of 23 hours and 17 minutes were spent actually surveying (that is, disregarding 

transit times). Two hours were spent on surveys that were omitted because of bad weather, leaving a 

total of about 21 hours and 17 minutes spent on usable surveys. Survey intensity averaged 3.9 min/km2

across all surveyed units, ranging from 2.35 to 5.28 min/km2 in the low and high-density strata, 

respectively (table 2). Differences in survey intensity among survey units and strata indicated variation 

in habitat complexity and the time required to count mountain goats and record observations, rather than 

any variation in our flight patterns. Detailed summaries of all individual flights and survey conditions 

are provided in appendixes 1 and 2, respectively. 
10 

Table 1. Mountain goat survey characteristics and raw counts of mountain goats in eight total count areas, and in 

high-, medium-, and low-density strata, Olympic Mountains, northwestern Washington, July 13–24, 2016.

[ha, hectare; min, minute; hr, hour; min/km2

, minute per square kilometer. Totals or averages are reported for each column 

depending on the quantity reported. ] 

Stratum Area 

(ha)

Number 

of units 

Area 

sampled

(ha)

Number 

of 

survey 

units

sampled

Percentage 

of stratum

surveyed

Survey

time

(hr) 

Survey 

intensity

(min/km2) 

Number of 

goats

observed

Total count areas 8,232 8 8,232 8 100 6.9 4.23 221

High density 5,534 12 5,534 12 100 4.3 5.28 114

Medium density 21,966 42 14,782 29 67 8.1 3.72 85

Low density 24,486 47 4,843 10 20 1.8 2.35 3 

Total 60,218 109 33,391 59 21.2 463

Average 55 3.9

Table 2. Population estimates of mountain goats, associated components of variance, standard errors, and 95-

percent confidence intervals in the Olympic Mountains survey area, northwestern Washington, 2004–2016.

[All numbers in table are number of mountain goats, except as otherwise noted. For comparison among years, estimates in 

2016 are computed for two survey unit definitions: (1) the expanded survey unit boundaries, which included suitable habitats 

at elevations above 1,425 meters (m), and (2) the original survey unit boundaries including lands at elevations above 1,520 

m. Variance component: Variance components as defined by Steinhorst and Samuel (1989) were computed following 

Wong (1996). Standard error: Computed as square root of total variance. NAVD 88, North American Vertical Datum of 

1988]

Year

Survey 

boundary 

definition

(meters above 

NAVD 88)

Estimate

(Number of

goats)

Variance component

Standard 

error

95-percent 

confidence 

interval Total Sampling Detection Modeling

2016 >1,425 623 1,846 771 424 651 43 561–741

2016 >1,520 584 1504 568 381 555 39 528–689

2011 >1,520 350 1,831 1,049 441 341 43 294–479

2004 >1,520 230 387 137 168 82 20 205–293
11 

Population Abundance

A total of 463 mountain goats were counted in the four strata (table 1, fig. 2, additional detail is 

provided in appendix 3). The estimated population of mountain goats in the Olympic Mountains survey 

area corrected for detection bias was 623 ±43 (SE) at the time of the survey (table 2). The total variance 

of the population estimate, Var(τ̂), was 1,846, which accounts for variance associated with random 

sampling of survey units (Varsampling=771 or 42 percent of the total), random detections of independent 

groups (Vardetection=424 or 23 percent of total), and uncertainty in model estimation (Varmodel=651 or 35 

percent of total). The 95-percent confidence interval ranged from 561 to 741 mountain goats. Strictly 

interpreted, the confidence interval of the estimate implies that if the exact same mountain goat survey 

were replicated many times, 95 percent of the resulting confidence intervals would include the true 

mean. Informally, the confidence interval often is considered the range in which we would expect to 

find the true population size if it were known (Mills, 2013, p. 18). 

Minimum population indices based on unadjusted counts of mountain goats in the Olympic 

Mountains ranged from a high of 764 ±116 (SE) in 1983, to a low of 181 ±15 (SE) in 1997 several years 

following the cessation of experimental removals (fig. 3). The population index increased from about 

191 ±10 (SE) in 2004 to about 516 ±27 (SE) in 2011. Differences between the estimated abundance and 

minimum population index each year represent the estimated undercounting bias associated with using 

the uncorrected raw counts of mountain goats. 

Population Trends

Population estimates corrected for detection biases and adjusted for comparable survey 

boundaries were 230 ±20 (SE) mountain goats in 2004, 350 ±43 (SE) mountain goats in 2011, and 584 

±39 (SE) mountain goats in 2016 (table 2, fig. 3). Compared with the overall abundance estimate of 623 

mountain goats, the estimate of 584 mountain goats reported here corresponds with the more restricted 

survey boundaries used in previous years. The estimated population in the expanded survey area was 

about 7 percent greater than in the previous survey area, representing mountain goats observed in the 

newly added area at elevations between 1,425 and 1,520 m. 

Based on population estimates of mountain goats in comparable survey boundaries, mountain 

goat abundance was significantly greater in 2016 than in 2011 (z=4.63, P<0.01). The z-statistic 

indicated that a difference in population estimates of the observed magnitude (or greater) would occur 

less than 1 percent of the time if the null hypothesis of equal population size was true. The estimated 

population of mountain goats increased at an instantaneous rate (r) of 0.06 ±0.02 (SE) between 2004 

and 2011, 0.10 ±0.02 (SE) between 2011 and 2016, and at an overall rate of 0.08 ±0.01 (SE) for the 

combined period of 2004–16. These instantaneous rates convert to average annual finite rates of growth 

approximating 6 percent annually from 2004 to 2011, 11 percent annually from 2011 to 2016, and 8 

percent annually over the combined 12-year period (that is, λ=1.06, 1.11, and 1.08, respectively). 
12 

Figure 3. Graph showing trends in the minimum population index and estimated population abundance (±standard 

error) of mountain goats in the Olympic Mountains, northwestern Washington, 1983–2016. All estimates 

correspond with survey unit boundaries at elevation contours above 1,520 m and included the Mount Washington 

survey unit. 

Discussion

The mountain goat population in the Olympic Mountains, which remained at relatively low 

numbers during the 1990s and began increasing after 2004 (Jenkins and others, 2012), continued to 

increase between 2011 and 2016. The observed exponential rate of increase, r, measured between 2004 

and 2016 (0.08 ±0.01 [SE]) was less than but comparable (based on the SE) to that measured for the 

Klahhane Ridge subpopulation during its documented increase in the 1960s and 1970s (about 0.09; 

Houston and Stevens, 1988). 

Comparison of population growth rates from 2011 to 2016 (r=0.10) compared to 2004–11 

(r=0.06) suggested that the rate of population increase may have accelerated after 2011. We caution, 

however, that poor counting conditions may have resulted in a low population estimate in 2011. Such an 

underestimation would result in an underestimation of actual population growth from 2004 to 2011 and 

an overestimation of population growth after 2011. The 2011 surveys followed one of the deepest snow 

years and latest season snow melts on record in the Olympic Mountains (Jenkins and others, 2012). In 

Jenkins and others (2012), we speculated that deep snow may have hindered the seasonal movement of 

mountain goats to high-elevation survey areas during 2011, or that the prevailing white background of 

snow may have resulted in greater than average detection biases. We cannot, however, rule out the 

alternative possibility that severe winter and spring conditions in early 2011 promoted a high level of 

over-winter mortality (White and others, 2011) also contributing to the low population estimate. 
13 

In contrast to conditions that raised uncertainties in the interpretation of 2011 surveys, optimal 

survey conditions, funding, and interagency cooperation all contributed to a successful survey in 2016. 

Snowfall during winter 2015–16 was approximately normal, but early snow melt promoted optimal 

phenology and forage conditions during the survey period. As evidence that mountain goats were 

distributed at higher elevations in 2016 than in 2011, we found only 7 percent of observations in the 

lower elevations of the survey area (between 1,425 and 1,520 m) during 2016, compared to 14 percent 

of observations in 2011 (Jenkins and others, 2012). Furthermore, because of optimal funding levels, 

survey logistics, and participation of WDFW biologists, we surveyed the largest proportion of goat 

habitat in 2016 (55 percent) than in any prior survey, contributing to relatively high survey precision. 

Our current estimate of population growth from 2004 to 2011 (r=0.06) was greater than we 

estimated in a previous report based on a smaller dataset without the Mount Washington unit (r=0.05; 

Jenkins and others, 2012). The difference in estimated rates of population growth is owing to the 

inclusion of the Mount Washington unit, where counts increased from 12 to 33 between 2004 and 2012. 

The number of mountain goats in the Mount Washington unit possibly increased from 2011 and 2012, 

consistent with the general population trends, which may have contributed to a slight overestimation in 

the 2004–11 rate of population growth. We suspect that because of this potential bias, the true rate of 

population growth for the entire population from 2004 to 2011 likely is between the previous and 

current estimates. 

The mountain goat population in the Olympic Mountains has sustained growth for more than a 

decade. Given uncertainties in the 2011 population estimate, the rate of population growth measured 

from 2004 to 2011 (r=0.08) likely is the best indication of near future trends. Over the next 5 years, if 

trends were to remain constant in the absence of density-dependent population responses or 

management intervention, we would expect the current population of about 623 mountain goats to 

increase by as much as 45 percent. Any extrapolation past that horizon is clouded by distinct 

possibilities that density-dependent demographic responses will begin to regulate population growth as 

was evident during the last population high mark (Houston and Stevens, 1988). 

Acknowledgments

This effort was funded principally by a National Park Service Natural Resources Preservation

Program. We would like to thank the Washington Department of Fish and Wildlife (WDFW) for 

providing additional resources and, specifically, Rich Harris, Cliff Rice, Brian Murphie, and Sara 

Kindschuh for conducting WDFW surveys. We thank the U.S. Forest Service, Olympic National Forest, 

for providing the necessary review and permissions to survey over wilderness; and Todd Rankin, 

Stephanie Frey, and the staff at the Emergency Operations Center and Dispatch Office at Olympic 

National Park for their help in aviation planning and communications during the surveys. Trevor 

Williams and Leah Brown were a huge help managing the helispots and assisting with helicopter 

operations. We are grateful to Rob Olmstead and Jess Hagerman (Northwest Helicopters) for safely 

piloting all surveys. We thank Cliff Rice (WDFW) and John Fieberg (University of Minnesota) for their 

long-term collaboration in developing and analyzing mountain goat sightability biases. We appreciate 

the lasting contributions of Doug Houston, Bruce Moorhead, Rich Olson, and Roger Hoffman at 

Olympic National Park, who established the mountain goat population survey design and produced the 

earlier population estimates in the Olympic Mountains. This manuscript was improved by helpful 

comments provided by two anonymous reviewers. 
14 

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16 

Appendix 1. Survey Flight Characteristics during Aerial Mountain Goat Surveys, Olympic Mountains, 

Northwestern Washington, 2016 

[Survey duration: Total time spent on surveys excluding time spent flying to and among survey units. Navigator/observer: Operated Global Positioning System 

during surveys. Primary observer: Focused on searching for goats at all times. Secondary observer: Data recorder: recorded all observations and covariate data]

Flight 

No. Date

Departure 

time (a.m. 

PDT) 

Departure 

location

Arrival 

Time Arrival location Flight duration 

(hours:min)

Survey duration

(hours:min)

Personnel/seating position

Right front: 

Pilot

Left back: 

Navigator/ 

observer

Left front: 

Primary 

observer

Right back: 

Secondary 

observer

ONP011 7/13/2016 5:40 Port Angeles 8:10 Sweets Field 2:29 1:57 Olmstead Beirne Happe Baccus

ONP02 7/14/2016 5:20 Port Angeles 7:18 Obstruction 1:58 1:14 Olmstead Beirne Happe Baccus

ONP03 7/14/2016 7:37 Obstruction 9:43 Obstruction 2:06 1:38 Olmstead Beirne Happe Baccus

ONP04 7/14/2016 10:03 Obstruction 11:12 Sweets Field 1:08 0:30 Olmstead Beirne Happe Baccus

ONP05 7/15/2016 5:15 Sweets Field 8:12 Obstruction 2:57 2:22 Olmstead Beirne Happe Baccus

ONP06 7/15/2016 8:41 Obstruction 10:41 Sweets Field 2:00 1:38 Olmstead Beirne Happe Baccus

ONP07 7/16/2016 5:17 Sweets Field 7:46 Obstruction 2:29 1:59 Olmstead Beirne Happe Baccus

ONP08 7/16/2016 8:07 Obstruction 10:24 Sweets Field 2:17 1:58 Olmstead Beirne Happe Baccus

ONP09 7/17/2013 5:14 Sweets Field 7:42 Obstruction 2:28 1:52 Olmstead Beirne Happe Baccus

ONP101 7/17/2013 8:03 Obstruction 9:15 Sweets Field 1:12 0:41 Olmstead Beirne Happe Baccus

ONP11 7/24/2016 5:26 Obstruction 6:59 Obstruction 1:33 1:23 Olmstead Beirne Happe Baccus

ONP12 7/24/2016 7:26 Obstruction 9:29 Obstruction 2:03 1:33 Olmstead Beirne Happe Baccus

ONP13 7/24/2016 9:52 Obstruction 11:29 Shelton Airport 1:37 1:07 Olmstead Beirne Happe Baccus

W01 7/14/2016 6:15 Olympia . Bremerton . 1:53 Hagerman Rice Harris Kindschuh

W021 7/14/2016 . Bremerton 12:45 Olympia 25:30 1:32 Hagerman Rice Harris Kindschuh

Total 

hours 31:47 23:17

1

Survey curtailed because of deteriorating weather. 

2

Flight duration calculations include refueling time. Estimated flight hours are 5 hours and 30 minutes for the Washington Department of Fish and Wildlife surveys.
17 

Appendix 2. Survey Characteristics and Environmental Conditions Measured at the Beginning of Each 

Unit Surveyed in the Olympic Mountains, Northwestern Washington, 2016 

[Polygons are subunits that are used for data recording and survey planning. Duration of survey in each surveyed unit. Ppt: Precipitation level. At elevation: 

Elevation at which air temperature was recorded, in feet above North American Vertical Datum of 1988. Light refers to lighting conditions during the survey. High 

lighting casts shadows whereas flat lighting does not. oC, degrees Celsius; ft, feet; h, hour; min, minute; sec, second; km2

, square kilometer. No data were recorded 

during the survey for table cells that are left blank] 

Flight 

No. Date Unit ID Polygon ID(s) Unit area 

(km2) 

Survey 

duration 

(hh:min:sec)

Survey 

intensity 

(min:sec/km2)

Sky condition Winds Ppt

Cloud 

cover 

(percent)

Temp 

(

oC)

At 

elevation 

(ft)

Light

ONP-01 7/13/2016 143W 143W 2.6 0:15:10 0:05:55 clear calm none 0 4 5,500 Flat

ONP-01 7/13/2016 141 141, 142 3.8 0:24:00 0:06:23 clear calm none 0 Flat

ONP-01 7/13/2016 129 129 6.7 0:23:28 0:03:31 clear

ONP-01 7/13/2016 1137 139, 137 part (

1

) 0:33:18 (

1

) mostly clear- fog calm none 30 Flat

ONP-01 7/13/2016 145 145, 146, 147 5.3 0:21:25 0:04:05 mostly cloudy calm none 50 Flat

ONP-02 7/14/2016 122 122 4.0 0:14:46 0:03:42 clear light none 0 7 5,000 Flat

ONP-02 7/14/2016 127S 127S 3.5 0:19:00 0:05:30 clear calm none 0 Flat

ONP-02 7/14/2016 125 125, 126 5.5 0:39:59 0:07:15 clear light none 0

ONP-03 7/14/2016 125 128 9.1 0:43:28 0:04:46 clear calm none 0 8 5,000

ONP-03 7/14/2016 127N 127N 2.3 0:20:32 0:08:46

ONP-03 7/14/2016 130 130 5.8 0:33:44 0:05:46 clear calm none 20 7 6,000 High

ONP-04 7/14/2016 35 35 5.6 0:12:21 0:02:13 clear calm none 0 9 5,000 High

ONP-04 7/14/2016 27 27 5.5 0:18:09 0:03:17 clear calm none 0 9 5,000 High

ONP-05 7/15/2016 119 119, 120, 121 3.8 0:22:43 0:06:01 clear moderate none 0 8 5,000 Flat

ONP-05 7/15/2016 110 110, 111, 112, 113, 150 6.6 0:18:54 0:02:52 clear light none 0 Flat

ONP-05 7/15/2016 115 115 6.1 0:31:13 0:05:08 clear light none 0 9

ONP-05 7/15/2016 116W 116W 3.8 0:14:52 0:03:52 clear light none 0

ONP-05 7/15/2016 124 124 7.0 0:29:37 0:04:15 clear light none 0

ONP-05 7/15/2016 131 131 6.7 0:24:45 0:03:43 clear light none 0 8 6,000 High

ONP-06 7/15/2016 102 102 5.6 0:15:37 0:02:48 clear light none 0 8 6,000

ONP-06 7/15/2016 101 101, 104, 107 4.9 0:29:48 0:06:07

ONP-06 7/15/2016 109 109 3.6 0:12:42 0:03:30 clear light none 0
18 

Flight 

No. Date Unit ID Polygon ID(s) Unit area 

(km2) 

Survey 

duration 

(hh:min:sec)

Survey 

intensity 

(min:sec/km2)

Sky condition Winds Ppt

Cloud 

cover 

(percent)

Temp 

(

oC)

At 

elevation 

(ft)

Light

ONP-06 7/15/2016 105 105,106 5.0 0:13:33 0:02:43 clear light none 0

ONP-06 7/15/2016 70 70 5.1 0:14:44 0:02:53 clear light none 0

ONP-06 7/15/2016 49 49 5.1 0:11:37 0:02:17 clear light none 0

ONP-07 7/16/2016 69 69, 78, 103 14.2 1:46:24 0:04:55 mostly clear calm none 0 9 5,000 Flat

ONP-07 7/16/2016 73W 73W 3.0 (

2

) (

2

) mostly cloudy calm none 60 Flat

ONP-07 7/16/2016 73E 73E 4.4 (

2

) (

2

)

ONP-07 7/16/2016 32 32 4.8 0:13:05 0:02:45 mostly clear calm none 0 8 7,000 High

ONP-08 7/16/2016 137 139, 137 12.4 1:15:06 (

3

) clear calm none 0 10 5,000 High

ONP-08 7/16/2016 138 138 5.7 (

2

) (

2

) clear calm none 10 9 6,000 High

ONP-08 7/16/2016 143E 143E 4.0 0:18:56 0:04:41

ONP-08 7/16/2016 144 144 7.1 0:24:05 0:03:25

ONP-09 7/17/2013 11 3 (

1

) 0:11:55 (

1

) mostly clear calm none 10 9 5,000 Flat

ONP-09 7/17/2013 54 54 5.1 0:23:58 0:02:23 clear calm none 0 Flat

ONP-09 7/17/2013 52 52 4.9 (

2

) (

2

) clear calm none 0 Flat

ONP-09 7/17/2013 44 44 5.3 0:32:05 0:02:52 mostly clear calm none High

ONP-09 7/17/2013 45 45 5.9 (

2

) (

2

) mostly clear calm none 15 Flat

ONP-09 7/17/2013 46 46 5.8 0:10:29 0:01:49 mostly clear calm none 20 Flat

ONP-09 7/17/2013 42 42 6.1 0:10:56 0:01:48 mostly clear calm none 10 High

ONP-09 7/17/2013 17 17 4.4 0:08:27 0:01:55 mostly clear calm none 15 Flat

ONP-09 7/17/2013 16 16 4.5 0:05:55 0:01:19 mostly clear calm none 15 Flat

ONP-09 7/17/2013 22 22 4.9 0:08:12 0:01:40 mostly clear calm none High

ONP-10 7/17/2013 11 4 (

1

) 0:21:04 (

1

) mostly cloudy 10 Flat

ONP-10 7/17/2013 117 117, 118 5.0 0:20:04 0:03:59 mostly cloudy light none 70 11 4,000 Flat

ONP-11 7/24/2016 1 2,3,4 19.3 1:10:10 0:03:38 clear light none 0 12 6,000

ONP-11 7/24/2016 24 24 4.7 0:12:27 0:02:39 clear light none 0 12 6,000 High

ONP-12 7/24/2016 64 64 4.1 0:15:50 0:03:50 clear light none 0 12 6,000 High

ONP-12 7/24/2016 65W 65W 4.0 0:19:28 0:04:53 clear light none 0 High

ONP-12 7/24/2016 85 85 5.4 0:20:57 0:03:53 clear light none 0 High

ONP-12 7/24/2016 50 50 5.0 0:17:51 0:03:34 clear light none 0 High

ONP-12 7/24/2016 48 48 6.9 0:18:26 0:02:41 clear light none 0 12 7,000 High
19 

Flight 

No. Date Unit ID Polygon ID(s) Unit area 

(km2) 

Survey 

duration 

(hh:min:sec)

Survey 

intensity 

(min:sec/km2)

Sky condition Winds Ppt

Cloud 

cover 

(percent)

Temp 

(

oC)

At 

elevation 

(ft)

Light

ONP-13 7/24/2016 98 98 6.3 0:31:23 0:05:01 clear light none 0 12 5,000 High

ONP-13 7/24/2016 96 96 5.8 0:21:30 0:03:42 clear light none 0 High

ONP-13 7/24/2016 97 97 2.7 0:14:04 0:05:08 clear light none 0 13 5,000 High

W-01 7/14/2016 99 100 7.2 0:34:00 0:04:43 clear 9 4,000

W-01 7/14/2016 90 99 0.8 0:04:00 0:04:50 clear 6 5,000

W-01 7/14/2016 90 90 3.6 0:14:00 0:03:51 clear 4 5,500

W-01 7/14/2016 91 91 1.7 0:05:00 0:02:55 clear 4 6,000

W-01 7/14/2016 91 92 2.6 0:06:00 0:02:19 clear 5 5,500

W-01 7/14/2016 93 93 5.8 0:18:00 0:03:07 clear

W-01 7/14/2016 196 96 (

1

) 0:19:00 (

1

) clear - fog 5 5,500

W-01 7/14/2016 197 97 (

1

) 0:13:00 (

1

) clear - fog 4 5,500

W-02 7/14/2016 198 98 (

1

) 0:26:00 (

1

) clear - fog 6 5,000

W-02 7/14/2016 95 95 2.2 0:08:00 0:03:38 clear 6 5,500

W-02 7/14/2016 83 83 6.0 0:18:00 0:03:00

W-02 7/14/2016 82 82 4.7 0:18:00 0:03:51

W-02 7/14/2016 81E 81E 4.7 0:22:00 0:04:40 7 5,500

1

Survey was curtailed because of deteriorating weather. Not all unit was surveyed. Unit was counted later on another flight. 

2

Unit(s) were surveyed with preceding units. Time and intensity values are for the group of units surveyed together. 

3

Unit was surveyed on multiple flights. Survey effort calculations are not valid. 
20 

Appendix 3. Raw Counts of Mountain Goats by Survey Unit, Olympic 

Mountains, Northwestern Washington, 2016 

[For each unit, the number of mountain goats observed in the part of the survey unit at elevations below 1,520 

meters above North American Vertical Datum of 1988 is noted in parentheses. Stratum: TCA, Total Count Area;

H, high density; M, medium density; L, low density]

Stratum Unit ID Unit name

Number

of 

groups

Total Adults Kids

TCA 1 Klahhane Total Count 12 35 28 7

TCA 69 Chimney Total Count 44 76 63 13

TCA 90 Sawtooths 3 8 6 2

TCA 91 Gladys/Henderson 0

TCA 93 Mount Skokomish 4 9 8 1

TCA 99 Mount Washington 3 23 18 5

TCA 125 Olympus Total Count 41 91 (5) 75 16

TCA 137 Carrie Total Count 8 19 17 2

H 73W Mount Anderson West 13 31 25 6

H 81E Steel East 3 5 5 0

H 98 The Brothers 6 7 (1) 7 0

H 115 Seattle 3 3 3 0

H 122 Paull Creek 10 19 (5) 15 4

H 127N Olympus Summit North 4 13 (6) 8 5

H 127S Olympus Summit South 0

H 129 Glacier Meadows 7 12 (3) 9 3

H 130 Mount Mathias 1 1 1 0

H 131 Mount Childs 6 17 15 2

H 141 High Divide/Bogaciel 4 5 4 1

H 143W High Divide West 1 1 1 0

M 27 Moose Lake 0

M 44 Mount Deception 1 1 1 0

M 45 Royal Lake 0

M 48 Mount Fromme 0

M 49 Thousand Acre Meadow 1 1 1 0

M 50 Wellesley Peak 1 2 2 0

M 52 Mount Mystery 0

M 54 Sunnybrook Meadows 0

M 65 Constance West 1 2 2 0

M 70 Sentinel 1 5 3 2

M 73E Mount Anderson East 5 5 5 0

M 82 Hart Lake 1 1 1 0

M 83 LaCrosse 1 5 4 1

M 85 Mount Elk Lick 1 1 1 0
21 

Stratum Unit ID Unit name

Number

of 

groups

Total Adults Kids

M 95 Mount Hopper 0

M 96 Lena Lake 0

M 97 Mount Bretherton 1 1 1 0

M 101 Muncaster 5 23 (4) 18 5

M 102 Rustler 2 2 2 0

M 105 Delabarre 1 1 1 0

M 110 Muncaster 0

M 117 Mount Dana. 0

M 116W Mount Queets West 2 7 5 2

M 119 Valhallas 8 9(1) 9 0

M 124 Mount Barnes 3 6(2) 5 1

M 138 Long Creek 4 9 7 2

M 143E High Divide East 0

M 144 Appleton 2 4 4 0

M 145 Boulder Peak 0

L 16 Elk Mountain 0

L 17 Elk Mountain East 0

L 22 Badger 0

L 24 Lillian River 0

L 32 Mount Cameron 0

L 35 Cameron Creek 0

L 42 Baldy 0

L 46 Royal Creek 0

L 64 The Gargoyles 0

L 109 Christie 2 3 2 1

Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

 Director, Forest and Rangeland Ecosystem Science Center

U.S. Geological Survey

777 NW 9th St., Suite 400

Corvallis, Oregon 97330

http://fresc.usgs.gov/
ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20161185

Jenkins and others—Mountain Goat Abundance and Population Trends in the Olympic Mountains, Washington, 2016—Open-File Report 2016–1185