Northern Bobwhite and the Weather

By Krista Ruppert, Texas A&M WFSC ‘16

When managing for bobwhite, it is important to take as many aspects of management and nature as possible into consideration. One area that absolutely cannot be overlooked is the weather. Northern bobwhite, particularly those found in arid environments such as in South and West Texas, are rather sensitive to changes in weather. From heat loads to precipitation levels, taking all forms of weather into account is essential for quail population management.

Traditionally, the amount of yearly precipitation was the full extent of weather considerations for quail. While this is an undoubtedly important aspect, perhaps the most important aspect, it is not a complete view of how weather affects quail. During periods of drought, survival, reproductive effort, and productivity are greatly reduced, to the point that the quail may not be productive enough to sustain the population. Additionally, drought can lead to a smaller percentage of hens nesting, a lower nesting rate, a shorter nesting season, and a lower rate of survival. To combat this dip in productivity, reduction of harvest pressure during periods of drought could be a potential aid. Drought will typically occur over longer periods of time with sporadic rainfall, but even during a wet season, the timing of precipitation as it related to the bobwhite life history must be considered.

A group of bobwhites in a dry, open area. Extra care is necessary during times of drought to ensure the health and survival of quail.
Photo from Texas A&M Agrilife Extension.

One of the reasons precipitation is so important to northern bobwhite is the effect it has on vegetation; it influences the height, structure, and function of vegetation essential to bobwhite life. If the precipitation is out of sync with bobwhite life history events, the vegetation may not be able to perform the functions needed by the quail, making it useless. Quail need vegetation for nesting habitat, food sources, and a source of water, as well as temperature control. Additionally, rain in the spring lines up with the reproduction of invertebrates, an important food source for hatchling quail, and encourages it by forming a favorable environment through moist soil. Spring rainfall leads to invertebrate reproduction, which in turn leads to greater quail survival. If rain occurs in the summer or fall, however, life history events are no longer in sync. Precipitation did not occur in the spring, so invertebrate populations are reduced. Quail nesting may have occurred in the spring without rain or in the summer/fall with it, but in either case the result is not favorable. The environment is out of sync, and quail survival rates will suffer. While there is not much that can be done management-wise for sparse precipitation, treating the symptoms of drought, such as high temperatures, could be helpful. If drought conditions are severe and you are considering supplemental water for quail, check out the blog post Supplemental Water for Quail to learn more. Though a lack of rain in dry areas is problematic, the opposite holds true for wet coastal areas. Too much rain can flood nests, thus washing away eggs, and can also cause an overgrowth of vegetation that chicks are unable to navigate. 

When these eggs hatch, the bobwhite chick hatchlings will need lots of protein from insects in order to survive. Without spring rain, there may not be many insects for them to eat, endangering their ability to survive.
Photo from Texas A&M Agrilife Extension.

Quail are not only sensitive to precipitation rates and times, but also to heat loads. A temperature of 102ᵒF is widely considered to be the maximum tolerated operative temperature (the temperature of the bird’s environment when all factors are taken into account) for bobwhite quail over long periods of time, as anything higher can lead to reduced hatchability of eggs, pre-mature incubation and staggered hatching dates, inferior chicks, mortality of young chicks through hyperthermia, and reduced chick survival by inhibiting foraging time. If temperatures rise much higher, it can lead to mortality of adult birds, a reduced proportion of hens that participate in reproduction, a reduced potential number of nesting attempts per hen, a reduced clutch size, and a shorter laying season. These effects will often lead to changes in age ratios, and tie in directly with precipitation and times of drought. Also important to consider is that ground temperature is often much higher than air temperature. Rain is effective in reducing heat loads, whereas overbearing temperatures are more likely to occur in times of drought. Preserving woody cover and allowing small areas of brush can give the overheated quail some shade and decrease temperature in nests, reducing heat loads and increasing survival rates. Types of plant cover are described in the blog post Plant Cover for Texas Quail. Additionally, ensuring that overgrazing does not occur can benefit quail greatly in terms of cover and proper nesting areas, which are especially important to consider during times of drought. Even if there are intermittent clumps of suitable nesting material present, if they are surrounded by overgrazed areas nests could still reach dangerous temperatures.

A male bobwhite in brush cover. Plant cover like this is essential for bobwhite survival. 
Photo from Texas A&M Agrilife Extension.

While temperature and precipitation can be decent predictors of quail population changes, they do not take into account all aspects of a drought. Rather than looking at only these two aspects, it could be helpful to use the Modified Palmer Drought Severity Index (MPDI) for population predictions. It is a method for climatologists to determine the severity of a drought by looking at a variety of factors including soil moisture, and it has a stronger correlation to changes in quail abundance than precipitation alone, allowing comparisons to populations to be completed quicker. Palmer maps are published through the National Integrative Drought Information System (NIDIS) each week by the National Oceanic and Atmospheric Administration, so the information is always available and professionally measured. This tool is especially useful in overall arid regions, such as in South and West Texas, where changes in weather have far more dramatic effect on quail than more humid environments.

An example Palmer map. Maps are updated each week, so drought information is always up-to-date. 
Photo from NIDIS.

To conclude, assessing changes in weather is critical to the management of quail. Rain in the spring and lower summer temperatures are excellent for quail survival, while drought and high heat loads can be detrimental. To better ensure the health of quail during these times, reducing harvest rates, preserving plant cover, controlling grazing, and monitoring populations with comparisons to the MPDI are the most widely agreed-upon methods for success.

For more information about quail management, see the following Texas A&M AgriLife Extension videos, as well as others on the channel:

Brush Sculpting to Improve Quail Habitat

Grazing Management for Quail

Quail Management: Coping with Drought

Literature Cited

Bridges, A. S. 1999. “Abundance of Northern Bobwhite and Scaled Quail in Texas: Influence of Weather and Land-Cover Change.” Thesis, Texas A&M University, College Station.

Bridges, A. S., M. J. Peterson, N. J. Silvy, F. E. Smeins, and X. B. Wu. 2001. “Differential Influence of Weather on Regional Quail Abundance in Texas.” The Journal of Wildlife Management 65(1):10-181.

Guthery, F. S., C. L. Land, and B. W. Hall. 2001. “Heat Loads on Reproducing Bobwhites in the Semiarid Subtropics.” The Journal of Wildlife Management 65(1):111-117.

Hernandez, Fidel, Froylan Hernandez, J. A. Arredondo, F. C. Bryant, L. A. Brennan, and R. L. Bingham. 2005. “Influence of precipitation on demographics of northern bobwhites in southern Texas.” Wildlife Society Bulletin 33(3):1071-1079.

Lusk, J. J., F. S. Guthery, R. R. George, M. J. Peterson, and S. J. DeMaso. 2002. “Relative Abundance of Bobwhites in Relation to Weather and Land Use.” The Journal of Wildlife Management 66(4):1040-1051.

Parent, C. J., F. Hernandez, L. A. Brennan, D. B. Wester, F. C. Bryant, and M. J. Schnupp.  2016. “Northern Bobwhite Abundance in Relation to Precipitation and Landscape Structure.”  The Journal of Wildlife Management 80(1):7–18.

Tri, A. N., J. P. Sands, M. C. Buelow, D. Williford, E. M. Wehland, J. A. Larson, K. A. Brazil, J. B. Hardin, F. Hernandez, L. A. Brennan. 2012. “Impacts of Weather on Northern Bobwhite Sex Ratios, Body Mass, and Annual Production in South Texas.” The Journal of Wildlife Management 77(3):579–586.