an article I found on quailrestoration.com... about predators..

Responsible Predator Management
There are two tiers of predators: nest predators and adult bird predators.
Nest Predators
Snakes - Small Mesomammals: Opossum, Raccoons, Skunks - Fireants - Foxes - Egrets - Armadillos
Most research shows that snakes are the number one predator on quail eggs in most areas. Raccoons, possums, skunks and armadillos account for the majority of the remaining losses.There has been a question whether or not turkey are nest predators. Researchers from the Tall Timbers Research Station in Tallahassee, FL have placed infrared cameras and observed native quail nests. In an area heavily populated with turkey, not a single nest was lost due to turkey. Snake, raccoons and armadillos were the major culprits.
Although many believe that the most damage comes from avian predators, research shows that far more potential quail are lost in the nest, before having a chance to hatch. These predators destroy eggs and chicks up to about 3 weeks of age. Studies differ, but many suggest that the above predators account for around 80% of quail losses. In one Texas county, research showed 100% of nests lost due to these predators. Research indicates that snakes are responsible for a disproportionate number of losses to eggs and chicks.
Adult bird predators
Adult bird predators consist of hawks, owls, bobcats, foxes, house cats, etc.It is important to realize that the greatest numbers of quail losses occur when they are young. For every one quail, surviving to adulthood, eight were killed before reaching 3 weeks of age.
Hawks are the most effective predator on adult birds. Some research shows about 35% of adult quail losses can be attributed to hawks.
Coyotes are one of the least effective predators on adult quail. Considering that coyotes are at the top of the food chain in most parts of the country, they can be beneficial in restoring the natural balance of an Eco-system. Coyotes have always kept the numbers of small predators such as raccoons, opossums, etc. in check by preying on their young. The reduction of the coyote population has caused a surge in the populations of those small predators, increasing the danger to quail eggs and chicks.In addition, increasing numbers of rats and mice allow for an increase in the snake population; one of the worst predators on quail nest and chicks.
When managing your property for quail, we suggest leaving the coyote population alone. We also recommend that you let trappers trap on your property during the normal trapping season.