Mary Caswell Stoddard

Tel: +44 (0) 1223 331 861
Fax: +44 (0) 1223 336 676
Email: mcs66 at cam.ac.uk

Position held: PhD student
(supervisor: Rebecca Kilner)

Research
 
My PhD research explores avian colour perception and evolution of eggshell colour and pattern. Even to the human eye, the world of egg colour is vibrant and varied. But how do these eggs appear to birds, whose visual systems are far more advanced than our own? My project with Dr. Rebecca Kilner and Dr. Martin Stevens involves analyzing eggshells using methods based on avian – not human – vision in order to appropriately investigate egg colour and pattern variation in a phylogenetic context. This work, based in the ornithological collections of the Cambridge University Museum of Zoology, uses digital cameras and avian visual processing models to evaluate eggs as birds see them. I am also interested in the function of egg colour and pattern, and I will conduct field experiments to test whether egg appearance has an effect on provisioning effort by great tit parents.
 
Past Research
 

As an undergraduate at Yale, I studied plumage colour evolution with Dr. Richard Prum. We used the avian tetrahedral colour space to describe phylogenetic patterns of plumage evolution in New World buntings.  My senior thesis documented the evolution of various structural and pigmentary colour mechanisms in bird feathers.  In the summer of 2007, I investigated gull breeding ecology with Dr. Julie Ellis at Cornell University’s Shoals Marine Laboratory on Appledore Island, Maine.

TETRACOLORSPACE

The visual systems of birds, many other reptiles, and many fishes include four color-sensitive retinal cone types. As a consequence, their color vision is more complex than human color vision. Stoddard and Prum (2008) developed a new computational tool that will allow users to model the visual color stimuli for these tetrahedral visual systems. TETRACOLORSPACE is a computer program developed for the tetrahedral analysis of colors measured from reflectance spectra or four cone stimulus values, using MATLAB 7 software (MathWorks, Natick, MA).

TETRACOLORSPACE can analyze colors based on ultraviolet or violet cone-type avian visual systems, or use any four cone-sensitivity functions input by the user. TETRACOLORSPACE provides an assortment of quantitative analyses and graphical tools for describing color stimulus variation and diversity. Details are available in Stoddard and Prum (2008).

TETRACOLORSPACE is provided for free here. When using the program, please cite the original publication:

Stoddard, M. C. & Prum, R. O. 2008. Evolution of avian plumage color in a tetrahedral color space: A phylogenetic analysis of new world buntings. American Naturalist, 171, 755-776.

Download the TETRACOLORSPACE program.
Download the TETRACOLORSPACE User’s Manual.

 
 
Publications
 
  • Stevens, M., M. C. Stoddard, and J.P. Higham. 2009. Studying primate color: towards visual system dependent methods. International Journal of Primatology: 1-25.
  • Stoddard, M.C. and R.O. Prum. 2008. Evolution of avian plumage color in a tetrahedral colour space: a phylogenetic analysis of New World buntings. American Naturalist 171:755–776.
  • Ellis, J.C., M.C. Stoddard, and L.W. Clark. 2008. Breeding by a Lesser Black-backed Gull (Larus fuscus) on the Atlantic coast of North America. North American Birds 61(4):546-548.

Cassie Stoddard
 
Research
Publications
 
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, U. K.