The Influence of Agriculture on Mule Deer Movement and Survival in the Texas Panhandle
Laura Warner: M.S. Graduate Research Assistant, Caesar Kleberg Wildlife Research Institute, Texas A&M University – Kingsville
Jacob Lampman: M.S. Graduate Research Assistant, Borderlands Research Institute for Natural Resource Management, Sul Ross State University
Project Overview:
Mule deer are an important game species in the Texas Panhandle, but little is known about their movements and survival in this region, especially in relation to agricultural production. Since crops are utilized by mule deer to supplement natural forage, deer may travel longer distances or shift their home ranges seasonally to make use of crops in this region. In addition, crops may increase mule deer survival by providing supplemental nutrition. On the other hand, movement to access agricultural fields may decrease survival by making the deer more susceptible to hunter harvest, vehicle collision, or predation. Understanding how mule deer use agriculture seasonally and how this affects their movement, productivity, and survival is crucial to their management. More accurate surveys can also be conducted by determining when and how far deer travel to crop fields from rangeland. Improved survey accuracy means that harvest limits will be better-suited to maintain viable deer populations. Furthermore, if deer use an excessive amount of cropland, it may indicate a need for habitat management to increase natural forage on rangeland. Mule deer productivity is significantly influenced by nutrition. Therefore, any changes in amount, distribution, or type of crops could impact mule deer trends. This crop-driven nutritional effect is relatively invisible to many land managers, yet the effects on mule deer productivity could be far-reaching.
Project Objectives:
To study the influence of agriculture production on mule deer by:
1. Evaluating sex- and age-specific differences in mule deer movements relative to agriculture crops yearly and seasonally, paying particular attention to periods of breeding, gestation, fawning, and lactation in females,
2. Investigating the effect of agriculture on survival of adult and fawn mule deer, and
3. Documenting mule deer seasonal diets and nutritional content of native forage and crops.
Current Progress:
We captured 73 mule deer in the Western Rolling Plains region near Turkey, Texas during October 2015. This is the first of 3 study sites that will be investigated during the 5-year study. Mule deer were captured using a helicopter and net-gun. Of the 73 deer, 43 were adults (18 bucks & 25 does) and 30 were fawns. Both adults and fawns were fitted with radio-collars, aged, and measurements were taken to determine antler size on bucks, body growth, weight, and body condition. Adult collars take GPS fixes once every two hours, allowing deer movement during the study to be intensively monitored. Fawn collars are not equipped to store GPS location data; however, both types of collars can be located using radio telemetry. By using weekly telemetry, we will track deer movement and monitor survival at each study site for 2 years. Fawn movements and home range size will also be estimated by using telemetry. If a collar is not moved for 4-6 hours, it will transmit a mortality signal. We then locate the collars using telemetry and determine cause of death for each deer by field necropsy and observation. To monitor crop use of deer, crop fields in the study area are identified and growth stages are assigned monthly. This crop timeline is then used with the location data from the collars to determine when deer are using certain crops.
Plant and fecal samples are being collected to document mule deer seasonal diet and nutritional contents of their native forage and crops. Fresh fecal samples from deer are being collected and taken back to a lab to be pulverized and analyzed. This allows us to put the samples underneath a microscope and identify parts of plant cells that will tell us which plants the deer have been eating. These data indicate what native forage and crops they are eating and at which growth stage crops are particularly attractive.
Samples of leaves, stems, and fruits from plants that deer eat will also be collected and pulverized to determine the nutritional value of each plant species during different times of the year. Data from these plant samples will specify which plants and crops are most nutritious and at which growth stage their nutritional values peak. Comparing that data to the fecal data will tell us why deer are eating those particular plants during a certain time of year. It will also show us if deer using agricultural crops are on a higher nutritional plane compared to those using primarily native forage. In turn, this will reveal if there is a correlation between crop use and higher body weights, antler size, and survival rates.
Presently, there are 51 of the 73 collared mule deer that remain alive at the study site. Of the adult deer, 4 bucks were harvested by hunters, and 4 does were lost due to unknown causes. Of the fawns, 13 were lost due to likely predation, disease, poaching or unknown causes. One fawn collar was found on a barbed wire fence, indicating that the fence broke the collar off of the deer and the fawn was not dead when we found the collar. More data over the course of the study must be collected in order to observe trends and make any conclusions about the cause of fawn mortalities.
Upcoming Work:
Deer movements and crops will continue to be monitored for another year at the present study site. In October, deer at the site in Turkey will be recaptured to download collar location data and measure body condition again before refitting the collar for another year. This will allow us to see where the deer have been and how their body condition has changed with their diet. In addition, 30 new fawns will be collared at the site. Also in October, a new study site in the Canadian River Breaks will be chosen, and 73 deer will be captured and collared there as well.
Additional Help:
Any additional help is always appreciated. Game camera pictures or reports of sightings of tagged deer are useful in knowing the general areas of where specific deer can be found during the monitoring stage. If you would like to share your sightings or would like to know more information about the project you can contact TPWD Wildlife Biologist, Dana Wright at (806)596-4016 or (Dana.Wright@tpwd.texas.gov), Jacob Lampman (jrl15uc@sulross.edu), or Laura Warner (laura.warner@students.tamuk.edu).
Funding:
Thank you to the organizations and foundations that have made this project possible through their generous funding!
- Texas Parks and Wildlife Department
- U. S. Fish and Wildlife Service Wildlife Restoration Program
- The Mule Deer Foundation
- San Antonio Livestock Exposition
- The Boone and Crockett Fellowship for Big Game Research, Texas A&M University – Kingsville
- Caesar Kleberg Wildlife Research Institute
- Borderlands Research Institute
- Texas Tech University Department of Natural Resource Management
And most importantly, thank you to all the landowners that have allowed us to capture and monitor mule deer on your property. Also a big thanks to those who have housed us during our frequent trips to the study site. Without your generosity and support, the project would not be possible.
Meet the Graduate Students on the Mule Deer Project
Laura Warner
My name is Laura Warner, and I am from rural Michigan. I grew up hunting and fishing with my dad and often tagged along on hunting trips before I could even hold a gun up to my shoulder. My interest in the outdoors developed into a passion for studying wildlife and its ecology. Pursuing a career in wildlife management, I attended Central Michigan University, where I received a Bachelor of Science in Natural Resources. As a Ronald E. McNair Scholar, I conducted undergraduate research studying the vigilance behavior of foraging chipmunks. Before coming to Texas, I worked as a hunting control station manager at the Patuxent Research Refuge in Laurel, Maryland. There I also participated in research with the USGS testing new types of radio-transmitter harnesses on ducks. Presently, I am pursuing a Master’s Degree in Range and Wildlife Management at Texas A&M University – Kingsville through the Caesar Kleberg Wildlife Research Institute under Dr. David Hewitt.
Jacob Lampman
My name is Jacob Lampman and I grew up on a small farm east of San Antonio in Marion, Texas. While growing up I spent a lot of time at my grandparent’s ranch where I developed a great love for the outdoors and wildlife. It wasn’t until high school that I discovered that wildlife management was a field of study that could be pursued through college and as a career. So I decided to major in Wildlife and Fisheries Sciences at Texas A&M University. Texas A&M provided me with many volunteer opportunities to gain different experiences, including a study abroad to South Africa. While working as a technician on a project with Bobwhite Quail I decided to continue my education. I am now working towards a Master’s Degree in Natural Resource Management at Sul Ross State University under the advisement of Dr. Louis Harveson.