BOBWHITES AND UPLAND WILDLIFE

RESEARCH HIGHLIGHTS

The breadth and scope of research conducted by the Bollenbach Chair can be seen by accessing publications from the home page.

Habitat Ecology and Management

The primary research emphasis for the Bollenbach Chair has been habitat ecology and management. The work has revolved around three issues: simple descriptive analysis of cover use, evaluation of habitat management programs, and evaluation of the usable space hypothesis in habitat management.

Simple descriptive analysis of cover use provides information on what quail select and what they avoid. This work has involved bobwhites, scaled quail, and Gambel’s quail in the United States and masked bobwhites in the United States and Mexico. Descriptive data from the Buenos Aires National Wildlife Refuge in Arizona showed how the cover on the refuge could be managed to favor the different species of quail.

With collaborators from Oklahoma State University and the U.S. Forest Service, the Bollenbach Chair was involved in analysis of bobwhite response to habitat management for red-cockaded woodpeckers in the Ouachita National Forest, Arkansas. The work revealed that habitat management for woodpeckers benefited bobwhites. Optimal management for bobwhites was thinning of mature pine-hardwood stands followed by prescribed burning on a 3-year rotation.

The Bollenbach Chair formalized the usable space hypothesis of habitat management in an article that appeared in 1997. In contrast to the notion that we should manage for habitat quality (edge, diversity, interspersion, food supplies), the usable space hypothesis implies that quality variables are weak relative to simple habitat quantity (the amount of suitable permanent cover on an area). In a study done on 78 farms and ranches in Oklahoma, usable spaced trumped habitat quality as a predictor of bobwhite abundance. Likewise, usable space appeared to predict bobwhite abundance better than habitat quality variables in Arkansas. These results support the usable space hypothesis and refute the habitat quality hypothesis.

The habitat emphasis will continue into the future. The Bollenbach Chair is embarking on a study of the ecology and management of sand plum. This plant is extremely important to bobwhites and other upland birds.

Harvest Management

Because bobwhites are declining in most of America, management biologists have become aware of concerns over harvest management. The Bollenbach Chair recently initiated an analysis of historical records of quail abundance and harvest with the collaboration of state biologists from Missouri, Kansas, Oklahoma, Texas, and Arizona. Some of the major findings were

Under fixed (the same each year), liberal harvest regulations (large daily bags, long seasons), quail harvest in states actually is self-accelerating rather than self-limiting, as it has long been supposed to be. This occurs in part because skill of the average hunter goes down as the quail population goes up.

Daily bag limits would have to be severely reduced (2 or 3 birds/day) to have any appreciable impact on the percentage of the state quail population harvested.

Within the framework of fixed, liberal regulations, the quail population itself governs the rate of harvest and the skill of hunters.

Continuing studies in harvest management will involve the comparative behavior of quail and quail hunters on a public hunting area. We also will be measuring bird dogs and hunters to determine how far they travel on a hunt. This has implications for the theory of the hunter-covey interface, which originated with the Bollenbach Chair.

Thermal Ecology

Heat and high temperatures are a major enemy of bobwhites, although this fact is little appreciated. To understand the behavior of these birds in the field, we must understand how they respond to temperatures in the cover types they use. The Bollenbach Chair and his students initiated an innovative study of the thermal ecology of bobwhites in 2000. The study involved satellite imagery, field sampling of thermal conditions, and radio transmitters that gave the temperature bobwhites were experiencing throughout the day. The following are some preliminary findings based of the 3-year study in north Texas:

Incubating bobwhites may go into thermal stress at an air temperature of 27 C (80 F).

After mid-June, incubating bobwhites are in thermal stress for about 1.5 hours each day.

The mid-day coverts used by bobwhites on hot summer days protect from heat overloads but bobwhites still experience times of thermal stress.

These results supported the heat hypothesis of bobwhite reproduction: annual variation in head loads at quail level explains a large portion of annual variation in production. High temperatures cause hens to go out of laying condition and may prevent late starters from nesting at all.

Weather Effects

Bobwhites in semiarid environments are extremely sensitive to annual variation in rainfall and temperature. Our chore in dealing with this sensitivity is to understand in the sense of predictive equations how populations respond to weather variables. Accordingly, the Bollenbach Chair and his students have spent a good deal of effort in modeling quail-weather relations in Arizona, Texas, and Oklahoma. Some findings are

Bobwhite populations seem to be more sensitive to deviations from normal weather conditions than to the absolute values of weather variables (e.g., total rainfall, maximum average temperature).

Both temperature and rainfall govern quail production. Quail populations may reveal good production in dry summers if temperatures are cool; however, cool temperatures during dry summers are rare. Likewise, quail populations may have weak production in rainy summers if temperatures are hot.

Bobwhite populations in the Rolling Plains, Edwards Plateau, and Rio Grande Plains of Texas showed evidence of cyclicity (rhythmic fluctuations in abundance) during 1978–2002. Peaks and troughs in abundance appeared at 5–6-year intervals.

Theory Development

The Bollenbach Chair has developed theory to estimate the quantity of usable space on an area based on use-availability data. For example, bobwhites might spend 30% of their time (use) in a cover type that occupies 15% of an area (availability). The use of cover types might be determined with telemetry and the availability with GIS. Knowing the amount of usable space on an area, the manager can estimate how a population would respond to cover management. As a further aid to management decisions, the Bollenbach Chair has developed mathematical logic to determine how much of particular cover types to remove and replace to maximize bobwhite density on an area.

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