Lyman Dudley - July 2018

No Stone Left Unturned: Searching the Talus

Looking for pikas in the summer heat is brutal work. I have spent five of the last six weeks putting in 12-14 hour days climbing around to different talus patches checking each one for pika occupancy, and looking for fecal pellets for stress samples. Pikas can’t handle the midday heat well, so a typical day for me involves waking up at 6:00AM, hitting the trail at 7:00AM, hiking 12+ miles with a typical 3000+ ft of elevation gain, taking a four hour break up at the top between noon and 4PM, and then sampling all the way down the watershed, usually getting back to camp at 7 or 8PM. Part of the reason why we are doing such long hikes with a large elevation gain is because we want to have the largest elevational gradient possible to track the full extent of upslope range retraction for pikas. Sampling a patch typically takes an hour since you have to climb around the talus looking for hay piles and pellets, or until a pika decides to come out and call at you. Most patches involve bushwhacking through thick vegetation straight up a hill for several hundred feet and then climbing up talus for an additional several hundred feet. This fieldwork puts a pretty big strain on knees, ankles, and leg muscles. We will likely only be surveying for three more weeks, but even with the slightly shortened field season, we will have ended up surveying over 700 patches over the course of the summer.

Thus far, my team has noticed that pikas are undergoing a higher rate of extirpation (local extinction) and upslope retraction in drier areas (typically the eastern sides of our mountain ranges). In fact in one drainage, pikas have already shifted upslope 2220 feet. Exposed, windy, high-elevation sites that have snow late into the summer have higher extirpation rates as well. Pikas prefer to live in cooler micro-climates such as deep talus, low lying depressions where cold air pooling occurs, areas with lots of shade (protection from the summer sun) and in areas near water with cooler, humid conditions. I have not yet done any lab work to run a GIS analysis on climate, elevation, and aspect effects on pika populations, but I will have over several thousand data points to pull from when I hit the lab in late August.

Image 1. A view from the office. This is Italian Peak, which lies on the Continental Divide and the Montana/Idaho border.

Image 2. Pikas and yellow-bellied marmots are often able to co-exist in patches. Marmots eat a lot more than pikas as this photo shows, so they typically live in talus that is near a meadow.

Image 3. A fresh hay pile. As the summer goes on these get bigger and easier to find as pikas add more fresh grass to them.

Image 4. A pika making an appearance above the talus. Don't let the cuteness fool you, pikas are vicious, cold blooded killers!

Image 5. It is important to get a full 8 hours of sleep a day, no matter where and when. This is me catching a few z's between patches.


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