Existing research on using passive acoustics to monitor Pika or other small, vocal mammals?

Question

I'm interested in using passive acoustics to monitor for the presence of pika (Ochotona spp.). I have found very few publications that consider pika vocalizations (none in the last decade), and none that have used passive acoustics for monitoring and/or density estimation. Are there other publications that I am missing?

Articles I have so far:

Conner, Douglas A. (1982). "Geographic Variation in Short Calls of Pikas (Ochotona princeps)". Journal of Mammalogy. 63 (1): 48–52. doi:10.2307/1380670. JSTOR 1380670.

Trefry, Sarah A.; Hik, David S. (2010). "Variation in pika (Ochotona collaris, O. princeps) vocalizations within and between populations". Ecography. 33 (4): 784–795. doi:10.1111/j.1600-0587.2009.05589.x.

Somers, Preston (1973). "Dialects in southern Rocky Mountain pikas, Ochotona princeps (Lagomorpha)". Animal Behaviour. 21: 124–137. doi:10.1016/S0003-3472(73)80050-8.

Answer 1

One potential lead may be this lab group at Oregon State University; I'm not super familiar with their work but do know they do a lot of PAM of spotted and barred owls and they have the below cited paper on automated detection in forests which it is able to detect/classify two small mammal species - the Douglas' squirrel and Townsend Chipmunk.

Ruff, Z. J., D. B. Lesmeister, C. L. Appel, and C. M. Sullivan. 2021. Workflow and convolutional neural network for automated identification of animal sounds. Ecological Indicators 124:107419.

They may have more info on ongoing efforts for small mammals! I saw one of their lab members (I'm pretty sure...) around on here so hopefully he will chime in with more!

EDIT!!!

They have a Twitter account that tweets out automatic detections (tied to the above paper) and I just went to find it to share the link here and what do you know...it says they now include pikas!!

Answer 2

I don't have any pika-specific references to add to your list, but can offer three ideas related to the "other vocal mammals" part of your question that may accelerate your project:

1. Having grown up in the Rocky Mountains and now experienced the Pacific Northwest, it might help to broaden your search to include marmots which also emit whistles at similar frequencies.
2. Many marine mammals emit whistles at similar frequencies, too, so you could search for odontocetes.
3. Search for articles that utilized the "whistle and moan" detector of PAMGUARD (free, open source software) and cross-reference with terms describing similar short whistles or similar sounds, like "squeak" or "chirp."

Answer 3

I've seen a bit of acoustic monitoring used for Flying Squirrels.

Here is one example.