By Mason Lee, Texas A&M WFSC '15
Many people nowadays strive for efficiency; in other words, they like to “kill two birds with one stone.” When it comes to ground nesting birds, this adage may hold all too true. Ground-nesting birds, as their name implies, are birds that nest on the ground rather than in trees. Many important game species in Texas are ground nesting birds, including quail, turkey, and pinnated grouses such as the Attwater’s prairie-chicken, greater prairie-chicken, and lesser prairie-chicken. However, these species are facing population declines in many parts of their ranges. One of the biggest factors contributing to the decline is habitat loss from changing land use, although factors such as depredation, introduction of non-native species, and biological stresses also have an impact.
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| Less than 50% of eastern wild turkey poults survive to be one month old due to depredation, starvation, birth defects, and inclement weather. |
Historic estimates place the
population of pinnated grouse between 1.3 million and 3.5 million birds (Silvy,
Peterson, and Lopez, 2004). Today, the greater prairie-chicken is now extinct
in Texas, and the lesser prairie-chicken and Attwater’s prairie-chicken are
listed under the Endangered Species Act as threatened and endangered,
respectively. The reason for their
decline has been attributed to a decrease in habitable space. In fact, less
than 1% of their original habitat in Texas remains (Silvy, Peterson, and Lopez,
2004). The loss of land due to agricultural conversion, urban and industrial
expansion, severe overgrazing, and invasion and chemical control of woody
species have contributed to the loss in populations of Texas quail species as
well (Brennan, 2007). This loss of habitable space makes it difficult for quail
and grouse to navigate between the fragmented patches.
The loss of habitable space also has other
implications for ground nesting birds. Montezuma quail are more susceptible to
avian depredation when protective cover is removed from their habitat (Brennan,
2007). In recent years, there has been a population increase in medium-sized predators,
including raccoons, gray foxes, and feral cats. This increase can be
contributed to the increase in fragmented habitat, supplemental feeding of
deer, farm ponds, and the demise of the fur market (Rollins and Carroll, 2001).
However, ground nesting bird depredation also occurs naturally without the
influence of man. Striped skunks, possums, and coyotes are major predators of
ground nests, and accipiters and northern harriers are common avian predators
of hatched bobwhites (Rollins and Carroll, 2001). Quail are able to counter
these high rates of depredation by renesting and producing large clutch sizes; however,
population growth may be inhibited in the face of increased depredation.
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| Raccoons are major nest predators of many ground nesting birds. |
Another major predator of ground
nests are feral hogs. In an experiment using dummy nests, feral hogs were the
most identified predator at 28% of all depredation events. In addition to these
large invasive predators, a smaller invasive species has also been taking a
toll on bobwhites. Red imported fire ants prey on bobwhite chicks (Brennan,
2007). In a study demonstrating the effects of fire ants on bobwhite chicks,
fire ants were responsible for 48.8% of chick mortality at hatching (Mueller et
al.).
In addition to these anthropogenic
factors, ground nesting birds face a variety of biological stresses. Changes in
precipitation are a major factor that contributes to decline. Droughts prevent
the growth of adequate amounts of cool season forbs, which in turn reduces
gambel quail nesting (Brennan, 2007). Some species of ground nesting birds just
simply have high mortality rates. For example, in the absence of predation,
disease, resource limitations, and inclement weather, 44% of bobwhites would
still die annually.
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| Under ideal conditions, the average lifespan of the northern bobwhite is about 6 months. |
Although some ground nesting bird
species have naturally high mortality rates, there are still many ways in which
humans can help reverse the decline of ground nesting birds. One of the most
important steps is to reclaim former habitat (Silvy, Peterson, and Lopez, 2004).
As Aldo Leopold, father of wildlife
management, wrote in 1933, these species “can be restored by the creative use
of the same tools which have heretofore destroyed it-ax, plow, cow,
fire,
and gun.”
Landowners and land managers can focus on improving habitat for ground nesting
birds using a mix of these techniques.
By restoring habitat, humans can effectively kill two birds with one
stone—improving habitat for one species often improves the habitat for a
multitude of other native species, such as the case with bobwhite quail and the
horned
lizard.
Information about the biology and management
of Texas ground nesting birds can be found on the AgriLife wildlife website.
Visit the AgriLife YouTube
Channel for videos detailing management practices for feral
hogs, quail,
and eastern
wild turkey, among others. In addition
to these resources, there are also various management publications available
for download on the AgriLife
Bookstore.
Literature cited
Brennan, L.A. 2007. Texas Quails. Texas A&M University
Press, College Station, USA.
Mueller, M. J., C.B. Dabbert, S. Demariais, and A.R.
Forbes. Northern bobwhite chick
mortality caused by red imported fire ants.
Rollins, D., and J.P. Carroll. 2001. Impacts of predation on
northern bobwhite and scaled quail. Wildlife Society Bulletin 29: 39-51.
Silvy, N. J., M.J. Peterson, and R.R. Lopez. 2004. The cause
of the decline of pinnated grouse: the Texas example. Wildlife Society Bulletin
32: 16-21.
Woodward, J.W. A., S.D. Fuhelndorf, D.M. Leslie, Jr., and J.
Shackford. 2001. Influence of landscape composition and change on lesser
prairie-chicken (Tympanuchus pallidicinctus) populations. American Midland
Naturalist 145: 261-274.