Parts of this story appeared in a previous edition of Quail Call. You can listen to and read the 2024 Quail Call here
Hardwoods such as oak, hickory, and sweetgum provide many wildlife benefits. However, for the quail manager, having too many hardwoods in the uplands where bobwhite are the primary goal can be counterproductive.
Hardwoods can affect bobwhite by outcompeting more desirable vegetation and by harboring bobwhite predators. Increases in hardwood density can happen if fire, mechanical thinning, or selective herbicide are not applied. Over time, if management does not address hardwood encroachment, the manager may see declines in bobwhite density.
Tall Timbers has seen this issue firsthand. In 1997-98, Tall Timbers underwent extensive hardwood removal across the property after decades of hardwood encroachment into upland areas.
This set the stage for increased mechanical treatments and prescribed fire the combination of which resulted in a shift in the understory vegetation towards grasses and forbs and away from hardwoods and vines.
As grasses increased prescribed fires became more effective and further shifted the groundstory to grasses, forbs and shrubby cover across the property. And importantly, bobwhite numbers increased 10-fold on Tall Timbers over the next 3 years to the highest quail densities since the 1970’s.
On several test sites in the Red Hills and Albany, bobwhite increased in numbers due to higher survival and higher nest production. Specifically, prior to hardwood removal, breeding season survival of adult quail averaged 40%. After hardwood removal, survival of adults increased to 57%. The timing of the adult bobwhite mortality also changed.
Prior to hardwood removal, predators killed 25% of adults during the last two weeks of April. After live oak removals, only 6% were lost during this period and survival remained high throughout the rest of the breeding season, which allowed for more total nests and more nests per hen during the breeding season. Bobwhite hens that incubated two or three nests produced 75% of the chicks for this population.
As illustrated above, hardwoods need to be carefully considered by the manager.
Not every hardwood tree needs to removed, and managers that have multiple goals for the property will need to carefully balance the tradeoffs of hardwood removal as it can negatively affect other species such as wild turkey.
That said, if a supplemental feeding program is in place, leaving hardwoods that provide an aesthetic benefit may be more important than their habitat value for wildlife. Further, when deciding which hardwoods to retain, consideration should be given to species composition as some species are fire tolerant and others are not. A forester or wildlife biologist can help you with that consideration.
But regardless, when bobwhite is the species of interest, hardwood density and position on the landscape needs to be under careful scrutiny. Often fewer than one hardwood per 5 to 10 acres in upland pine forests achieves the goals of quail management.
Mature overstory hardwoods can be removed at any time of the year although extensive clean-up is best done March through May to minimize ground disturbance during the breeding season and avoiding reducing escape cover during fall and winter. One of the best times to assess hardwood encroachment from developing trees is immediately after a prescribed fire.
Post-fire assessments will reveal hardwoods that have become too tall and are no longer providing cover for bobwhite and are shading out the understory and/or harboring predators.
Remember that bobwhite need shrub, vine, and bramble cover. But once it is above about 5’, it is moving away from what bobwhite need and is starting to be difficult to manage with fire alone. This is the time to treat these escaping patches of hardwoods with selective herbicide or cutting/mulching the trees and get their structure back to a desirable height.
In summary, removing hardwoods in and around upland pine communities can improve bobwhite habitat and survival. Habitat is improved in several ways.
First, by removing overstory hardwoods and small thickets of midstory hardwood saplings, more sunlight reaches the ground, allowing desirable cover to develop in the understory. Additionally, shading from hardwoods can reduce your ability to manage with prescribed fire as the shade limits fine fuel accumulation such as grass.
Further, removal of dense areas of hardwoods can reduce predator habitat for species such as raccoon, opossum, bobcat, and various snakes. Hardwoods are also often used by raptors for perches. Judicious removal of trees that may be serving as raptor perches can increase adult bobwhite survival.
For all these reasons, consider limiting hardwood density in upland areas where bobwhite is the primary goal. But be sure to maintain abundant low growing woody vegetation (shrubs, hardwood resprouts, vines, and brambles) to provide cover for bobwhite.
