2018 Marmot Monitoring Results

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Please click on a link above to view a summary of data from that year on the page below.

 

Photo by Ken & Mary Campbell (c)

Program Overview and Results of the 2018 Field Season

2018 was the 8th year of the program, and our second year back after taking a year off to analyze the data and evaluate the program. Following the program review, some of the survey units that were too hard to get to were dropped. We also moved some survey units from the core group (which we try to survey every year) to the group that gets surveyed occasionally. This was done for several reasons: 1) some units are just too hard to get to each year (e.g. Bailey Range and Skyline), 2) we had a lot of sampling in some areas (eg. High Divide region) and not enough in others (e.g. the southeast), and 3) we need to be able to schedule more repeated surveys in some areas so that the standard error around the detectability estimate is smaller, allowing us to detect a change better. Following those modifications, in 2018 the survey frame consisted of 370 survey units grouped into 71 clusters, with 159 survey units in 30 clusters assigned to the core group.
In 2018 we had 84 volunteers in 28 groups participate in the program; a total of 3590 volunteer hours were donated. Volunteer training was held on five Wednesdays in the month of August. In addition, NPS and partner staff helped out by surveying in hard to reach places. Following training, surveyors spent from 1-8 days in a variety of areas of the Park and Forest, ranging from the front-country on Hurricane Hill to deep in the park on Skyline Ridge. Surveyors in all regions traversed high-elevation meadows and rock-fields looking for and documenting sign of marmots and marmot burrows.
Marmot surveys were conducted in 276 survey units located in 56 habitat clusters. Surveyors were able to completely survey 251 units and partially survey 25 others (Figure 1).

 

Figure 1.  Units surveyed and signs of marmot occupancy, Olympic Peninsula, 2018

NPS

 

Figure 2. Annual trends in raw Olympic marmot occupancy in core survey units, Olympic National Park, 200-2018. The core consists of the same 151 units each year, but not all are completely surveyed every year due to access constraints or other factors.

NPS

Of the units that were completely surveyed in the core clusters in the park, 74% were found to be occupied by marmots, 16% were abandoned (surveyors saw past but not recent sign of marmot use) and 10% had no sign of marmots. The rate of occupancy averaged ranged from 56%-65% during the first 6 years of the study (Figure 2). When all units were combined, the overall marmot occupancy in 2018 was 58% (Figure 1).

 

Conclusions and Plans for 2019

Data from the first 6 years of the program were analyzed and interpreted in the Natural Resource Condition Assessment for Olympic National Park (McCaffery and Happe, 2018). It was determined that although marmots have disappeared from 40% of the colonies that were monitored from 1957-2015, most of that decline happened prior to 1990. From 2010 to 2015 the marmot occupancy remained relatively stable (between 50 and 60%). However, occupancy rates varied between regions of the study area, with occupancy being highest in the northeast (mean=69%) and lowest in the southeast and south west (<40%). Occupancy was also most stable in the northeast, and more erratic (e.g. greater turnover) in the southwest and southeast. In 2019 we are going to continue the monitoring effort, and put more emphasis in areas of greater concern, such as the southeast.

Acknowledgements

In 2018 this project was supported by a continuing grant from Washington's National Park Fund. This whole endeavor would not have been possible without the hard work of the volunteer citizen scientists!