Preble’s Meadow Jumping Mouse Sampling Update: North Fork Poudre Site Conservation Area

By Rob Schorr and Terutaka Funabashi, Colorado Natural Heritage Program (CNHP)

With funding from Colorado Parks and Wildlife, the Colorado Natural Heritage Program conducted Preble’s Meadow Jumping Mouse (PMJM) trapping and habitat surveys throughout the North Fork Poudre PMJM SCT Nomination Area starting in 2023.

In 2023, sites were selected randomly from “medium” and “high” quality habitat, but only sites with landowner permission were visited. Of the 11 sites accessed, PMJM were documented at 4 of those, with a total of 7 PMJM captured.

In 2024, to increase sample size, sites were chosen at random but were visited in geographically proximate groups to increase sampling efficiency. Thus, sites were not visited in random order. This increased sampling size to 16 sites, but PMJM were only documented at 3 sites, with a total of 5 PMJM captured. Capture success data from2023 and 2024 are shown below.

In 2025, random selection was abandoned and “access” and “habitat quality” were criteria for sampling sites. Locations were requested from area representatives and visited based on permission, and aerial photography and expert opinion of the habitat. Because of personnel loss, only 8 sites were visited and PMJM were captured at 5 sites, with 48 PMJM captures. A majority of those captures came from locations along western South Lone Pine and Elkhorn creeks. One location had 30 PMJM captures of 28 individuals. Data from 2025 is still being reviewed and entered, as some sites were being sampled last week.

This is the first attempt to quantify Preble’s meadow jumping mouse populations in a PMJM Site Conservation Area, and, as with all wildlife studies, revealed that we are still learning about the species’ distribution and abundance. Over the three years, CNHP sampled 35 sites within the North Fork of the Poudre River Watershed, with 12 sites having PMJM and 23 where PMJM were not detected. The Colorado Natural Heritage Program will be reviewing the captured data and comparing it to vegetation data at the same location to see if habitat condition gives us a clue to predicting PMJM presence.

“We are grateful to have this Site Conservation Team (SCT) operating in our watershed. The North Fork Poudre SCT supports habitat protection for wildlife as well as the long-term outlook for healthy ranch lands. We were excited to have our ranch be one of the monitoring sites for the jumping mouse, which will help us understand if we are doing all we can to keep our land and river in good shape.” – Nancy Carpenter, landowner

“The Roberts Ranch in Livermore is a Non-Profit Foundation that works in many ways to help understand the relationship between humans and the environment including wildlife, habitat improvement, active land management, and food production.  Working with the North Fork Poudre SCT to identify ways that we can be better stewards and understand our environment better is essential to building resilient communities.” – Zach Thode, rancher