Texas Quail Index 2016 Part 2: Summer Demonstrations

By Amanda Gobeli, Texas A&M AgriLife Extension Associate

If you missed Part 1, you can find it here.

From the beginning of June to the end of August, Texas Quail Index Cooperators perform three demonstrations to gauge habitat quality, predator abundance, and nest predation pressure on quail populations. These factors are critical in determining reproductive success for quail.

A quail nest bowl. Photo courtesy
of Becky Ruzicka.

Habitat evaluations are conducted by assigning scores to important aspects of quail habitat. These include the presence of nesting and escape cover, abundance and variety of food, proximity to water, and distribution of these resources across the landscape. Because quail do not often fly more than a few hundred yards (Hernández and Guthery 2012), a patchwork distribution of resources is critical to ensure that all needs are met within a relatively small area. Evaluators assign scores to the aforementioned parameters and the quality of the habitat overall (the “Evaluation Value”), which is ranked as follows: 

The statewide average habitat evaluation value for bobwhites was 0.70 (“good”) this year; this value and the average from 2015 (0.72) are both significantly higher than the 2014 value (0.67). Scaled (blue) quail habitat evaluations are similar with 2016 and 2015 averages of 0.69 and 0.71, respectively, which compare favorably to the 2014 value of 0.66. Nesting cover was the most significant limiting factor this year for both scaled and bobwhite quail, followed by abundance and diversity of woody cover. Bobwhite habitat scored higher in these parameters with values around 0.6, while scores in scaled quail country were closer to 0.5.

Statewide habitat evaluation averages. Nesting and Woody Cover describe the % area occupied by these cover types, Abundance/Variety and Availability refer to food resources, Water is proximity to a permanent water body, and Interspersion indicates diversity and placement of woody cover. The Evaluation Value describes the habitat overall.

Adequate nesting and woody cover are especially important for helping quail avoid their predators, which are the focus of the next two demonstrations. Dummy nests consist of 3 chicken eggs placed in suitable nesting substrate (bunch grass, prickly pear or low-growing shrub) to simulate a clutch of quail eggs. Nests are checked at 2 and 4 weeks and marked as survived (all eggs intact) or depredated; if possible, eggshell evidence or footprints are used to identify the culprit (Hernandez et al. 1997). Despite habitat quality remaining on par with 2015 values, dummy nest survival rates were about 10% lower this year (48%) relative to last year (60%). Regional averages tell a similar story and range from 29% survival in the High Plains to 56% in Cross Timbers. The alleged nest predators include raccoons, which accounted for 27% of depredation events, snakes (21%), coyotes (17%) and skunks (10%) among others.

Raccoons (Procyon lotor) are some of the most common quail 

nest predators. Photo courtesy of San Saba County.

What exactly is going on here, and how can we explain these seemingly high rates of nest predation? It is first necessary to give these results some context. Nest failure and frequent depredation events are necessary features of quail ecology, as nest success has been estimated as low as 28% with predators accounting for 80% of losses (Rollins and Carrol 2001).  Generally, a survival rate above 40% suggests that predation is not a significant limiting factor for quail nest success­. This year’s dummy nest survival rates, although lower than those in 2015, still reflect sustainable levels of predation. The most commonly identified predators are the ones we would expect to see based on previous research: raccoons are the top nest depredators in many areas due to sheer abundance, along with coyotes (Rollins 2011). One caveat is that snake depredations may be overestimated, as they are often assumed to be responsible if no eggshell evidence is left behind. However, hogs and other predators are capable of raiding a nest without leaving any shells or signs of rooting (Hernandez et al. 1997, Rollins 2011).

Feral pigs, Sus scrofa, are potential nest predators of quail. Photo courtesy
of U.S. Fish and Wildlife Service.

Another possible reason for increased predation rates is that predator populations are now catching up to booming prey populations. This is a well-established concept in ecology, referred to as “delayed density dependence,” which essentially states that an increase in prey means an increase in predators…but not immediately. It takes time for predator populations to respond to an increase in food availability (Begon et al. 2006). Quail populations increased dramatically in 2015; the conditions that made this resurgence possible would have helped other prey species as well and ultimately meant more food for predators. High predation rates may also be attributable to a shortage of suitable nesting cover rather than predator overabundance, as lack of cover makes nests easier to find and increases the likelihood of predation (Rollins and Carrol 2001).

Game cameras photographed more than 400 predators belonging to 14 different species this year, with coyotes and hogs accounting for almost 90% of the total. This might be surprising given that raccoons were identified as the primary predator of dummy nests, but the cameras are in different locations and are often positioned adjacent to roads. Highly invasive feral hogs have been a problem for decades, and coyotes have increased as well (Rollins and Carrol 2001), but does this mean predator control is warranted? Studies investigating the effects of intensive predator removal on bobwhite populations have found results ranging from a moderate increase in quail numbers to no effect at all (Rollins and Carrol 2001). There may also be unintended consequences of removing certain predators. Coyotes, for example, help keep populations of other quail predators in check (Ritchie and Johnson 2009). While control efforts may be effective in cases of severe predator overpopulation, generally it is a costly and labor-intensive endeavor with no guarantee of results. Habitat improvements—such as increasing the abundance and quality of nesting and escape cover—should always be considered before predator removal.

Coyotes (Canis latrans) were among the predators photographed by game cameras
and often make use of ranch roads. Photo courtesy of Ward County. 

The final Texas Quail Index demonstration is a series of roadside counts, which are conducted in September to measure quail abundance in the fall. These can indicate the survival rate of chicks hatched in the spring and provide an estimate of overall population density prior to hunting season and winter. Those results will be discussed in Part 3.

For more information, check out these resources:

Potential Predators Associated with Northern Bobwhite Nesting

Say Cheese: The Role of Cameras in Wildlife Management

Conducting Nest Clump Surveys

Literature Cited

1. Begon, M., C. R. Townsend, and J. L. Harper. 2006. Ecology: from individuals to ecosystems. 4th ed. Blackwell Pub, Malden, MA.
2. Hernández, F., and F. S. Guthery. 2012. Beef, Brush, and Bobwhites: Quail Management in Cattle Country. Texas A&M University Press.
3. Hernandez, F., D. Rollins, and R. Cantu. 1997. Evaluating Evidence to Identify Ground-Nest Predators in West Texas. Wildlife Society Bulletin 25:826–831.
4. Ritchie, E. G., and C. N. Johnson. 2009. Predator interactions, mesopredator release and biodiversity conservation. Ecology Letters 12:982–998.
5. Rollins, D. 2011. You Could Learn a lot from a Dummy. Texas Wildlife 20–23.
6. Rollins, D., and J. P. Carrol. 2001. Impacts of Predation on Northern Bobwhite and Scaled Quail. Wildlife Society Bulletin 29:39–51.