Deer populations on private and public lands in Central Florida are managed intensively for recreational opportunities, ecological integrity, and to balance deer populations with multiple goals within an agricultural landscape. On millions of acres of land in Florida, cattle ranching is integrated with forestry, citrus plantations and other crops, and hunting leases. Managers lack knowledge of deer use of habitats within active cattle ranching operations. Currently, no techniques are available to accurately age or survey white-tailed deer in this region. Under the direction of Dr. Gino D'Angelo and Dr. Karl V. Miller, masters student Jordan Dyal is conducting collaborative research with Florida Fish and Wildlife Conservation Commission to improve deer management to meet management goals.
The three primary research objectives include:
1) Evaluate the movements and habitat use of adult bucks on an active cattle ranch
2) Develop techniques to age deer on the hoof and after harvest
3) Develop accurate and efficient protocols to survey deer via aerial surveys
After successful net-gun capture, a restrained deer is being transported to a nearby work station to be fitted with ear tags and a GPS collar. After aging the buck by tooth eruption and wear and calculating its Boone and Crockett antler score researchers will release the buck at the processing site. The whole handling time takes less than 15 minutes.
This graph shows the movement path of a buck after his release. During Sep 8 -Feb 15 he used more than 4,500 acres. Frequent location data will allow Jordan to look at the effects of cattle grazing on this buck's use of the landscape.
Although this Florida buck is eager to put distance between himself and the capture team, he will unknowingly send location data for the duration of the study.
As testimony of the success of the helicopter capture process, this photo contains 3 GPS-collared bucks.
Jordan directs the capture helicopter into work-up area to drop off a buck, which will receive his eartags and GPS collar.
Tooth replacement and wear patterns are used to estimate age of a buck before its release.
Jordan and fellow graduate student, Adam Edge, release another buck from the August 2019 capture.
Current project status:
We conducted experimental sightability modeling flights with helicopters and drones. During August 26-29, 26 bucks and 21 fawns were captured with the aid of a helicopter and transported to a centrally located work-up area. We fitted 25 of these deer with GPS collars to allow us to monitor their subsequent movements. The helicopter crew was scheduled to catch deer for two additional days, but, Hurricane Dorian had a different plan. We first captured seven of the bucks in 2018, when they were fawns. We will intensively monitor movements of all GPS-collared deer and provide additional insight when possible.
We are analyzing central Florida buck movements using a step-selection function. There is much more to a traditional cattle operation than just livestock grazing. Pastures are routinely applied with herbicide, fertilizer, and biosolids to increase forage quantity and quality. Although previous research has analyzed deer movements relative to cattle presence, to our knowledge, no research has incorporated alternative traditional cattle management practices and their effect on deer movements. Therefore, we will evaluate deer movements relative to grazing pressure, herbicide, fertilizer biosolids, supplemental feeders, and landcover types.
A step-selection function compares an individual’s potential movements (available resources) to its actual “steps” we observe (used resources). Each individual’s available movements are determined by a distribution of their movement tendencies (observed step-length and direction of movement). Once established, step-length and direction of movement are drawn at random from the distribution to determine available movements. By using a step-selection function we can capture the temporal variability of each variable. For example, cattle are continuously rotated between pastures, so instead of assigning a single average grazing pressure to each pasture in a study site, each location is assigned a daily grazing pressure value.
Our goal is to determine how buck resource selection changes with each cattle management practice. The information obtained will be used to inform cattle and wildlife managers about which resources bucks select for and allow them to provide optimal resources across the landscape to promote deer populations.
The figure demonstrates how a step-selection function compares randomly generated potential movements (available locations; represented by O) based on each individual’s movement tendencies and their actual location (used location; represented by X). This statistical tool will allow us to meet our above goal.