Though somewhat controversial, the supplemental feeding of certain species of wildlife is commonly used as a means to manage their populations. In the southeastern United States, supplemental feeding is often used to manage northern bobwhites (quail), especially during the winter months when food is scarce. While much is known about the quails’ response to the feeding, the affects on nongame wildlife is less understood.

With this in mind,Georgia scientists Ivy A. Godboi and L. Mike Conner, both from the Joseph W. Jones Ecological Research Center, and Robert J. Warren of the Warnell School of Forest Resources, set out to examine how the supplemental feeding of quail affected the bobcat population on the grounds of a research center. Bobcats are top carnivores within the study area. They prey on rodents, such as cotton rats that are attracted to the grain used to manage the quail population. The researchers wanted to learn whether the presence of supplemental food for quail, regularly distributed between November and May, altered the home range size or movements of the bobcats that share the 11,700 hectare field laboratory.

The researchers started their study in the fall of 2000 shortly after the usual feeding had begun on an outdoor laboratory facility in the Joseph W. Jones Ecological Research Center in Newton, Georgia. Over the next five months, the quails’ supplemental feeding of 270 metric tons of grain sorghum was distributed along field edges, food plots, and through upland pine dominated forests.

Concurrent with the feedings, beginning in December of 2000, researchers captured 16 bobcats, recorded their defining characteristics, uniquely tattooed them, and collared the adults with Advanced Telemetry Systems’ M2200 series Mammal Collar. The animals were then released and radio tracking began seven days later. The scientists recorded the animals’ locations twice a day, three times a week, varying the timing by two hours every week to ensure that an entire 24-hour period was sampled every 12 weeks.

To begin, researchers determined the home range estimates for all of the bobcats and converted them into digital thematic maps for further analysis. A tractor-mounted Global Positioning System (GPS) was then used to determine the locations of the supplemental food.

The home range calculations for a 12-month period were then combined with the number of GPS locations for each home range location. The researchers then used linear regression to examine the relationship between the home range of the bobcats and the availability of the supplemental food.

In the next phase of the project, the researchers analyzed:

• The effects of bobcat gender
• The percent area of the home range occupied by food plots
• An index of the amout of supplemental food within each bobcat’s home range
• The effects of supplemental food on bobcat home range size and movements

Animals that received no supplemental food within their home range during the entire period served as the control group. The researchers calculated home ranges for the 2001-2002 winter, when food was provided, and compared that to the summer of 2002 when food was not being provided. The scientists theorized that an examination of the fed versus the control groups and winter behavior versus summer would indicate whether the supplemental food altered the home range size of the bobcats.

After monitoring 16 bobcats over the course of the feeding period, researchers determined that home range sizes of the animals were not affected by the supplemental feeding. While home range sizes were found to be smaller during the winter when supplemental food was available, there was no evidence that supplemental food was responsible for the seasonal differences in home range size.

The researchers established that bobcats were found about 10 times closer to supplemental food sources than would be expected if the supplemental food had no effect. The rodent population was greater around the food source, as well. The amount of rodents in the bobcats’ diet seemed to indicate that the greater rodent concentration attracted bobcats in greater numbers than would be expected under normal circumstances.

Although the research sheds light on the behavior of animals with respect to supplemental feeding, it also generates additional questions for further study particularly on the indirect effects of supplemental feeding. For example:

• Does supplemental feeding attract other large predators?
• Does supplemental feeding affect the survival rate of prey by attracting additional predators?
• What is the effect of competition for supplemental food between wildlife species and the effects of predators on reducing that competition?

This study has examined just a few of the indirect implications of supplemental feeding. But it provides important information to the many landowners who make use of the practice. While the bobcat home range did not seem to be affected by the feeding, the predators did stay closer to the plentiful artificial food supply. Further study will provide additional insight into the relationship between predators, their prey, and supplemental feeding.

For more information on this research project, visit the Joseph W. Jones Ecological Research Center at http://www.jonesctr.org/index.html or contact us at ATS.