Integrative Organismal Biology Lab- An Odyssey of Strange Mice

Welcome. We are a group of organismal biologists exploring the interface of the inner & outer worlds of animals—where von Uexküll’s Umwelt meets Grinnell’s ecological niche. We integrate data from brains, behavior, physiology, & ecology to explore the organism from different perspectives. Current projects focus on how species interactions influence acoustic communication systems in rodents, a group of animals with underappreciated voices.

General topics of interest: Acoustic communication, behavioral endocrinology, cognitive ecology, mammalogy, Mexican borderlands, niche differentiation, species interactions


Clockwise from top left: Leonhard Stejneger, Frank Hall Knowlton, Vernon Bailey, C. Hart Merriam, and Florence Merriam Bailey (Smithsonian Institution Archives) “I reached Flagstaff July 26, 1889, & was joined next day by my assistant, Mr. Vernon Bailey. We proceeded to Little Spring, at the north base of the San Francisco Mountain. This was our base camp for two months, & from it numerous side-trips were made into the surrounding country.” -C. Hart Merriam, 1890


Calling male Southern grasshopper mouse (Onychomys torridus) “A long, fine, shrill whistle in a high key, insectlike in fineness & quality. It is the wolf’s howl in miniature, without rise or fall, & is made with raised nose and open mouth in perfect wolf form.” -Vernon Bailey, 1929

Bret Pasch
Assistant Professor
Department of Biological Sciences
Northern Arizona University
Flagstaff, AZ 86011


As organismal biologists, we’re interested in getting to know animals in the zoo de thoiry prix allowing them to suggest appropriate research questions*. We use field & laboratory experiments, physiological manipulations, physical modeling, & molecular neurobiology to explore wild rodents from proximate & ultimate perspectives. Current studies focus on acoustic communication & species interactions in Neotropical singing mice (Scotinomys) in montane cloud forests, & grasshopper mice (Onychomys) in the desert Southwest. Please see the links below (*to be added soon) to learn more about these animals & current research directions.

West-Eberhard, Mary Jane. 2001. The importance of taxon-centered research in biology. In: Ryan, Michael J., Anuran Communication. Smithsonian Institution Press.
Greene, Harry. 2005. Organisms in nature as a central focus for biology. Trends in Ecology and Evolution 20:23-27


Cornell University

University of Texas at Austin

University of Florida

University of Arizona


In review

Pasch, B., Sanford, R. and S. M. Phelps. Agonistic character displacement in social cognition of advertisement signals.

Mason, N. A., Pasch, B., Burns, K. J., and E. P. Derryberry. Of songs and specimens: integrating museum and media collections to study vocal evolution.


Pasch, B., Abbasi, M. Z., Wilson, M., Zhao, D., Searle, J. B., Webster, M. S., and A. N. Rice. Cross-fostering alters advertisement vocalizations of grasshopper mice (Onychomys): evidence for the developmental stress hypothesis. Physiology & Behavior. In press

2014 Campbell, P., Pasch, B., Warren, A. and S. M. Phelps. 2014. Vocal ontogeny in Neotropical singing mice (Scotinomys). PLoS ONE 9(12): e113628. link

Monaghan, J.R., Stier, A.C., Michonneau, F., Smith, M.D., Pasch, B., Maden, M., and A. Seifert. 2014. Experimentally induced metamorphosis in axolotls reduces regenerative rate and fidelity. Regeneration 1:2-14 link

2013 Pasch, B., B.M. Bolker, and S.M. Phelps. 2013. Interspecific dominance via vocal interactions mediates altitudinal zonation in Neotropical singing mice. American Naturalist. link

Pasch, B., and J.L. Pino. 2013. The cost of advertisement: Long-tailed weasels as potential acoustically-orienting predators of Neotropical singing mice. Southwestern Naturalist. 58:363-366. pdf

2012 Hayssen, V., Miranda, F., and B. Pasch. 2012. Cyclopes didactylus. Mammalian Species. 44: 51-58. pdf

Seifert, A.W., Monaghan, J.R., Smith, M.D., Pasch, B., Michonneau, F., Stier, A.C., and M. Maden. 2012. The influence of fundamental traits on mechanisms controlling appendage regeneration. Biological Reviews. 87:330-345. pdf

2011 Pasch, B., George, A.S., Campbell. P., and S.M. Phelps. 2011. Androgen-dependent vocal performance influences female preference in Neotropical sing mice. Animal Behaviour. 82: 177-183. pdf

In Focus: Featured Articles in this month’s issue: Performing Mice pdf

Pasch, B., George, A.S., Hamlin, H.J., Guillette, L.J., and S.M. Phelps. 2011. Androgens modulate song effort and aggression in Neotropical singing mice. Featured article in Hormones and Behavior 59: 90-97. pdf see e-article for audio

Pasch, B., and J.L. Koprowski. 2011. Impacts of fire suppression on space use by Mexican fox squirrels. Journal of Mammalogy. 92: 227-234. pdf

2010 Campbell, P., Pasch, B., Pino, J.L., Crino, O., Phillips, M., and S.M. Phelps. 2010. Geographic variation in the songs of Neotropical singing mice: testing the relative importance of drift and local adaptation. Evolution 64: 1955-1972. pdf

2009 Leonard, K.M., Pasch, B., and J.L. Koprowski. 2009. Sciurus pucheranii. Mammalian Species. 841: 1-4. pdf

2006 Pasch, B., and J.L. Koprowski. 2006. Sex differences in space use of Chiricahua fox squirrels. Journal of Mammalogy 87: 380-386. pdf

Pasch, B., and J.L. Koprowski. 2006. Annual cycles in body mass and reproduction of Chiricahua fox squirrels. Southwestern Naturalist 51: 531-535. pdf

Koprowski, J.L., Ramos-Lara, N., Pasch, B., and C. Zugmeyer. 2006. Observations on the ecology of the endemic Mearns’s Squirrel (Tamiasciurus mearnsi). Southwestern Naturalist 51: 426-430. pdf

2005 Pasch, B., and J.L. Koprowski. 2005. Correlates of vulnerability in Chiricahua fox squirrels. Pp. 426-428 in Connecting Mountain Islands and Desert Seas: Biodiversity and Management of the Madrean Archipelago II (G.J. Gottfried, B.S. Gebow, L.G. Eskew, and C.B. Edminster, eds.) Rocky Mountain Research Station, Fort Collins, Colorado. pdf

Koprowski, J.L., Edelman, A., Pasch, B., and D. Buecher. 2005. A dearth of data on the mammals of the Madrean Archipelago: What we think we know and what we actually do know. Pp. 412-415 in Connecting Mountain Islands and Desert Seas: Biodiversity and Management of the Madrean Archipelago II (G.J. Gottfried, B.S. Gebow, L.G. Eskew, and C.B. Edminster, eds.) Rocky Mountain Research Station, Fort Collins, Colorado. pdf


We strongly advocate dissemination of our science to the general public & have sought various opportunities to do so.

Cornell University Lab of Ornithology Education Program
University of Texas UTEACH
University of Florida SPICE
University of Arizona AZ-Sonora Desert Museum Docent Program

We also endeavor to communicate our research through popular media outlets.
for Pasch et al. 2013 in American Naturalist
National Geographic: Musical mice sing to fend off rivals
Smithsonian Magazine: Birds, wolves, howlers, and…
ABC News: Why mice sing
NBC News: Forest confrontations
University of Texas: Protecting Turf With High-Pitched Tunes
Tampa Tribune: #29

for Pasch et al. 2011 in Animal Behaviour
National Public Radio: Squeaking up a storm: Yes, that mouse is singing
Wired Magazine (UK): Singing mice prefer skilful vocalists
Science News- Macho mice make manly melodies
EarthSky: Singing mice woo mates with tiny serenades
University of Florida- When singing mice choose a mate, a skillful song gets the gal
Science Daily- …rock stars of the rodent world
Wild Mammal Blog- Singing mice top the charts
Int’l Business Times: A singing mouse, Eighth wonder of the world?
España- Radio y Televisión Española: Ratónes catarines parte 1 parte 2

for Pasch et al. 2011 in Hormones & Behavior
Argentina- La Búsqueda. Ciencia en la Radio – FM Ciudad 98.9 Vivitos y Sonando

for Pasch & Koprowski 2011 in Journal of Mammalogy
Press: The Wildlife Professional- Science in Short: Have Shrubs, Will Travel


Spring 2016

Animal Acoustics (BIO 300) Animal Acoustics explores the diverse use of sound across the animal kingdom, along with methods and techniques for studying animal sound communication. The course entails a mix of lectures, practicals, and field excursions aimed at understanding the biology of acoustic signals while gaining hands-on experience with sound recording, playback, and analysis. We strive to attain a broad appreciation for the evolution, development, mechanisms, and functions of this fundamental mode of animal communication.

Fall 2016

Mammalogy (BIO 528) “The diversity of topography ithin Arizona-from the great pine forests to the reasewood & cactus deserts, from high plateaus to deep anyons, and from grassy mountain meadows to shifting ands-is reflected in the diversity of mammals.” Hoffmeister 1986

“Probably nowhere else in the United States do more species (of small mammals) so closely related occur so close together, seemingly in the same ecological niche.” -Hoffmeister 1954