Master of Science Candidate

Student Background

I’m Cody Zabransky and I am pursuing my masters degree in range and wildlife management.  I was blessed to grow up with a family that enjoyed the outdoors and who supported me with everything I have pursued.  I graduated from Memorial High School in Houston, TX  in 2003 and graduated in 2007 from Texas A&M-Kingsville with my B.S. in range and wildlife management.  My involvement with the student chapter of The Wildlife Society as secretary then president has given me experiences and a network of professionals that will help throughout my career.  I've also been very active outside of school groups with several trophy managed private ranches and enjoyed opportunities to guide hunts for several species of wildlife.  My passions are hunting, fishing, and nature photography and rarely pass up an opportunity to do any of them.    I strongly believe that hard work, a positive attitude, and understanding the views of all parties involved will help me become an effective and successful steward of our natural resources.

Thesis Project

Influences on the Sightability of Mule Deer

To best manage wildlife populations, the number of animals in an area must be known.  Development of a sightability model for use by Texas Parks and Wildlife Department during their aerial surveys of mule deer will estimate the population of mule deer and help in making decisions on setting goals for mule deer management in Texas.  Sightability from helicopter surveys varies greatly as not all deer are counted on a survey resulting in an underestimate of true population.  Currently used raw data only allows biologists to evaluate trends in the population which may not be appropriate for management of a species that has experienced range-wide declines in population.  My project will propose and evaluate possible influences on the sightability of mule deer in six prominent mule deer habitat types.  A model will then be developed to correct for missed deer and deliver an estimated true population.  I will be utilizing 72 GPS collars on bucks and does to determine and quantify the influences of canopy cover, vegetation type, activity, terrain, light, and distance from transect on the sightability of mule deer.

Current Research Abstract 2009

Developing a Sightability Model for Mule Deer in West Texas

Abstract: Effective wildlife management requires knowledge of both population size and composition.   Such information has become particularly important in the management of mule deer, given their range-wide population declines.  The value of traditional mule deer population data is limited due the fact that not all animals are seen during aerial surveys, which result in trend data that are not as valuable as unbiased population estimates when setting regulations and goals for mule deer management in Texas.  The objective of this research project is to develop a sightability model for use in estimating mule deer population size and composition from aerial survey data.  Thirty-six collared deer on each of two study sites were used to identify and quantify factors impacting visibility of mule deer during helicopter surveys.  This study design is being used for 3 years in different parts of the current mule deer range in Texas.  Preliminary Program MARK data suggest that 40% of mule deer are seen from aerial surveys and there is no difference between sightability of males and females.  The probability of sighting a deer that is moving is 60% higher than the probability of seeing a mule deer that is not.  The probability of seeing a deer from the helicopter at 100m is 15-20% less than deer on the transect.  These preliminary results suggest that uncorrected aerial survey data may not accurately estimate mule deer population sizes in Texas.