A Morphometric Sex Determination Model for Adult Greater Roadrunners (Geococcyx californianus) Academic Article uri icon


  • 2014 The Wildlife Society. Little is known of the greater roadrunner's (Geococcyx californianus; roadrunner) ecology and many demographic questions are difficult to answer because of our inability to determine adult bird sex in the field. We collected measurements from live-captured roadrunners of known sex in Fisher County, Texas, USA, and from roadrunner specimens from museums and university biological collections from 2003 to 2012 to develop a predictive logistic regression model for adult sex determination. We measured 433 adult birds of which 80% (n = 346) were randomly chosen to build potential models. Our best model included the variable estimate bill depth, which was found to be larger in males and correctly classified 80% of the birds. We validated the model with the remaining 20% of measurements (n = 87) and correctly identified the sex of 85% of the birds. Because this model incorporated roadrunners from across their range, it provides an easy, inexpensive, accurate, and field-relevant methodology for sex determination of adult roadrunners at the point of capture.

published proceedings


altmetric score

  • 0.25

author list (cited authors)

  • Montalvo, A. E., Powell, R. A., MacDonald, M. D., Ransom, D. J., & Lopez, R. R.

citation count

  • 1

complete list of authors

  • Montalvo, Andrea E||Powell, Robert A||MacDonald, Michael D||Ransom, Dean Jr||Lopez, Roel R

publication date

  • December 2014