Evolution, Ecology & Organismal Biology

Christopher J. Clark

Sample Profile Graphic
Office: (951) 827-3646
Fax: (951) 827-4286
3344 Spieth Hall
Email: cclark@ucr.edu

Christopher J. Clark, Assistant Professor

Ph.D., University of California, Berkeley, May 2009


Profile in Google Scholar

Clark Lab homepage

My laboratory studies courtship displays, how feathers and wings produce sound, and bird flight biomechanics, using hummingbirds as a model system.

We study a variety of questions related to the sounds animals make when they fly, or, locomotion-induced sounds. All animal locomotion produces sound as an inevitable byproduct of motions (such as the sound of your footsteps in a hallway). Many animals have converted these incidental sounds into communication sounds, while owls instead have evolved adaptations to reduce the amount of sound produced in flight. We study how these sounds are produced, what function(s) they have, and how they evolve. 

The Animal Aeroacoustics lab has high-speed cameras and sound recording equipment for both field and lab work. We also have a couple optinav "acoustic cameras". We have a unique aeroacoustic wind tunnel with a 18" x 24" working section, modeled after the one built by Ennes Sarradj and colleagues.

Current and recent projects include:

  • Wind tunnel tests of feathers to determine the physical mechanisms by which they produce sound, especially directionality.
  • Performance of a physically demanding courtship display (Sean Wilcox's Ph.D.)
  • Song learning in Costa's Hummingbird (Katie Johnson's Ph.D.); hearing in hummingbirds (Ayala Berger Ph.D.)
  • Genomics of courtship behaviors a hummingbird hybrid zone between Allen's and Rufous Hummingbirds (Brian Myer's Ph.D.; in collaboration with Alan Brelsford and Kevin Burns)
  • Owl flight (Krista le Piane's Ph.D.)
    • Other projects include:
  • Hummingbird pollination biology (with Erin Rankin, Entomology)
  • High-speed video of courtship displays of wild hummingbirds (see youtube channel link above).
  • Assisted Patricia Brennan in studying the explosive erections of duck penises.
  • Hovering and forward flight mask respirometry of hummingbirds in a wind tunnel.
  • Evolution of courtship displays of the 'bee' hummingbirds.
  • Field work (for recording courtship displays): Costa Rica, Bahamas, Cuba, Guatemala, Mexico, Colombia, Ecuador, Chile, Uganda, Texas, Brazil, and of course, California.

I also participate in IDEA, the UCR Institute for the Development of Educational Applications.


  •  Clark, C. J., Mountcastle, A. M., Mistick, E. A., Elias, D. O. 2017.  Resonance frequencies of honeybee (Apis mellifera) wings. J. Exp. Biol., 220: 2697-2700. DOI: 10.1242/jeb.154609



    Clark, C. J. 2017.eBird records show substantial growth of the Allen's Hummingbird (Selasphorus sasin sedentarius) population in urban Southern California. The Condor: Ornithological Applications. 119: 122-130. doi: 10.1650/CONDOR-16-153.1


    Clark, C. J. 2016. Locomotion-Induced Sounds and Sonations: Mechanisms, Communication Function, and Relationship with Behavior. In Vertebrate Sound Production and Acoustic Communication (Suthers, R., and Fitch, T., eds.). Springer Handbook of Auditory Research, 53: 83-117.


    Clark, C. J., Kirschel, A. N. G., Hadjioannou, L., and Prum, R. O. 2016. Smithornis broadbills produce loud wing song by aeroelastic flutter of medial primary wing feathers. J. Exp. Biol., 219: 1069-1075. doi:10.1242/jeb.131664



    Clark, C. J. and Prum, R. O. 2015. Aeroelastic flutter of feathers, flight, and the evolution of nonvocal communication in birds. J. Exp. Biol. 218: 3520-3527. doi:10.1242/jeb.126458



    Feo, T. J, Musser, J., Berv, J. and Clark, C. J. 2015. Divergence in morphology, calls, song, mechanical sounds, and genetics supports species status for the Inaguan hummingbird (Trochilidae: Calliphlox "evelynae" lyrura). Auk, 132: 248-264. 10.1642/AUK-14-108.1



    Clark, C. J. 2014. Harmonic hopping, and both punctuated and gradual evolution of acoustic characters in Selasphorus hummingbird tail feathers. PLOS ONE, 9: 10.1371/journal.pone.0093829

  • Clark, C. J., Elias, D. O., Girard, M. B. and Prum, R. O. Forthcoming. Structural resonance and mode of flutter of hummingbird tail feathers. J. Exp Biol., 216: 3404-3413.
  • Clark, C. J., Elias, D. O., and Prum, R. O. Forthcoming. Hummingbird feather sounds are produced by aeroelastic flutter, not vortex-induced vibration. J. Exp Biol., 216: 3395-3403
  • Clark, C. J, Feo, T. J. and van Dongen, W. 2013. Sounds and courtship displays of the Peruvian Sheartail, Chilean Woodstar, Oasis Hummingbird, and a hybrid male Peruvian Sheartail x Chilean Woodstar. Condor, 115: 560-577.
  • Clark, C. J. 2012. The role of power versus energy in courtship: what is the "energetic cost" of a courtship display? Anim. Behav., 84: 269-277.
  • Clark, C. J., Elias, D., and Prum, R. O. 2011. Aeroelastic flutter produces hummingbird feather songs. Science, 333: 1430-1433.
  • Clark, C. J. 2011. Wing, tail, and vocal contributions to the complex signals of a courting Calliope Hummingbird. Curr. Zool, 57: 187-196.
  • Feo, T. J. and Clark, C. J. 2010. The displays and mechanical sounds of the Black-chinned Hummingbird (Trochilidae: Archilochus alexandri). Auk, 127: 787-796.
  • Clark, C. J. and Dudley, R. 2010. Hovering and forward flight energetics in Anna's and Allen's Hummingbirds. Physiol. Biochem. Zool. 83: 654-662. DOI: 10.1086/653477
  • Brennan, P. L. R., Clark, C. J. and Prum, R. O. 2010. Explosive eversion and functional morphology of the waterfowl penis supports sexual conflict in genitalia. Proc. R. Soc. Lond. B, 277: 1309-1314. DOI: 10.1098/rspb.2009.2139.
  • Clark, C. J. and Feo, T. J. 2010. Why do Calypte hummingbirds "sing" with both their tail and their syrinx? An apparent example of sexual sensory bias. Am. Nat., 175: 27-37.
  • Clark, C. J. 2009. Courtship dives of Anna's Hummingbird offer insights into flight performance limits. Proc. R. Soc. Lond. B. 276: 3047-3052.
  • Clark, C. J. and Dudley, R. 2009. Flight costs of long, sexually selected tails in hummingbirds. Proc. R. Soc. Lond. B. 276: 2109-2115.
  • Clark, C. J. 2008. Fluttering wing feathers produce the flight sounds of male streamertail hummingbirds. Biology Letters, 4: 341-344.
  • Clark, C. J. and Feo, T. J. 2008. The Anna's Hummingbird chirps with its tail: a new mechanism of sonation in birds. Proc. R. Soc. Lond. B. 275: 955-962.

    (click here for my CV)


  • Winters I teach half of Biol 161B, Comparative Vertebrate Anatomy, team taught with Tim Higham (or in W 2018, Mark Springer).
  • Fall quarters I teach Biol 163, Vertebrate Natural History, including 7 field trips over the course of the quarter.
  • Every other year I teach Biol 213, Behavioral Ecology (grad course)


More Information

General Campus Information

University of California, Riverside
900 University Ave.
Riverside, CA 92521
Tel: (951) 827-1012

Career OpportunitiesUCR Libraries
Campus StatusDirections to UCR

Department Information

Evolution, Ecology and Organismal Biology (EEOB)
2710 Life Sciences Bldg.

Tel: (951) 827-5903
Fax: (951) 827-4286
E-mail: bnnadmin@ucr.edu

Graduate Program
1140 Batchelor Hall
Tel: (951) 827-4116
Fax: (951) 827-5517
E-mail: eeobgrad@ucr.edu