Diego Sustaita
Diego Sustaita
Assistant Professor of Biological Sciences

Office: SCI I 211
Phone: 760-750-8240

I am fundamentally interested in ecomorphology, the study of an organism’s form and function in the context of its natural environment. Over the past few decades, the quintessential biological paradigm, “form means function,” has been reconfigured to address how variation in form translates into an organism’s physical ability to perform its ecological role. Birds provide an excellent system for investigating this paradigm, given that the great diversity of beak form among taxa is often functionally coupled to diet. Predatory birds, in particular, provide another dimension of phenotypic variability, because additional selection on foot form and function has dual implications for feeding as well as locomotor performance.


  • Postdoctoral Research & Teaching Associate, Brown University, 2016
  • Ph.D. Ecology & Evolutionary Biology, University of Connecticut, 2013
  • M.S. Biology, California State University, Northridge, 2005
  • B.S. Biology, California State University, Northridge, 2000

Understanding morphological variation in a functional context, guided by biomechanical principles. I used this approach to learn how musculoskeletal differences in the jaws and hindlimbs between hawks and falcons explained differences in their biting and grasping behavior (Fig. 1); to investigate the functional significance of the trifurcated deep digital flexor tendons of emu toes using X-ray Reconstruction of Moving Morphology (Fig. 2); and to understand the roles of proximally and distally-inserted digit flexor tendons in perching and grasping objects (Fig. 3).

Understanding functional performance capabilities, by quantifying the forces (kinetics) and movements (kinematics) of live animals. I use force sensors to measure the bite and grip strength of hawks, falcons, and shrikes (predatory songbirds) to understand how differences in jaw, beak, and foot morphology among species and individuals relate to differences in performance (Figs. 4, 5). I also use high-speed video to quantify prey-handling movements in captive shrikes (in collaboration with the San Diego Zoo Institute for Conservation Research and the U.S. Navy; Fig. 6), in an effort to understand the ontogenetic effects of bill shape on feeding performance (Sustaita et al. in prep.).

Understanding functional performance

Understanding foraging behavior, to relate performance capabilities to actual patterns of prey resource use in the wild. I use standard behavioral observation techniques, coupled with carbon and nitrogen stable isotope analysis of consumer and representative prey tissues, to assay predator feeding habits (Fig. 7). This step places information gleaned from the previous two approaches into an ecological context, ultimately to uncover the selective basis for phenotypic variation.

Foraging Behavior
Contributing to wildlife conservation and management. My research with the California Department of Fish & Wildlife (CDFW) regarding habitat use and population demography of the salt marsh harvest mouse addresses the management of endangered species (Fig. 8). On-going research efforts include the development of morphological tools for discriminating between similar harvest mouse species in the field, and establishing fine-scale vegetation-mouse associations.


Wildlife Conservation

Backus SB, Sustaita D, Odhner LU, Dollar AM. 2015. Mechanical analysis of avian feet: multiarticular muscles in grasping and perching. Royal Society Open Science 2: 140350; DOI: 10.1098/rsos.140350.

Hertel F, Maldonado JE, Sustaita D. 2015. Wing and hindlimb myology of vultures and raptors (Accipitriformes) in relation to locomotion and foraging. Acta Zoologica 96: 283-295.

Sustaita D, Rubega MA. 2014. The anatomy of a shrike bite: bill shape and bite performance in Loggerhead Shrikes. Biological Journal of the Linnean Society 112: 485-498.

Sustaita D, Owen CL, Villarreal JC, Rubega MA. 2014. Morphometric tools for sexing loggerhead shrikes in California. The Southwestern Naturalist 59: 560-567.

Burgio KR, Rubega MA, Sustaita D. 2014. Nest-building behavior of Monk Parakeets and insights into potential mechanisms for reducing damage to utility poles.  PeerJ 2:e601; DOI 10.7717/peerj.601.

Sustaita D, Pouydebat E, Manzano A, Abdala V, Hertel F, Herrel A. 2013. Getting a grip on tetrapod grasping: form, function, and evolution. Biological Reviews 88: 380-405.

Sustaita D, Quickert PF, Patterson L, Barthman-Thompson L, Estrella S. 2011. Salt marsh harvest mouse demography and habitat use in Suisun Marsh, California.  Journal of Wildlife Management 75: 1498-1507.

Sustaita D, Hertel, F. 2010. In-vivo bite and grip forces, morphology, and prey-killing behavior of North American accipiters (Accipitridae) and falcons (Falconidae).  Journal of Experimental Biology 213: 2617-2628.

Sustaita D. 2008. Musculoskeletal underpinnings to differences in killing behavior between North American accipiters (Falconiformes: Accipitridae) and falcons (Falconidae).  Journal of Morphology 269: 283-301.

  • Biol 212: Evolution, Fall 2016