Many people often think of predators as
being the “villains” of the natural world. Historically, predator control
campaigns were started to eradicate predators from ecosystems in order to
support the abundance of the prey species for game management. There has been a
gradual shift in this perception, however, as it is becoming more well-known
that predators and prey interact in complex ways. As Aldo Leopold stated, “…you
cannot love game and hate predators…the land is one organism.”
The mule deer (Odocoileus hemionus) population on the Kaibab Plateau famously
illustrates this belief. In the early 1900s, the main predators of mule deer on
the plateau were exterminated in a misguided attempt to preserve the deer
population. It appears that the subsequent absence of predators resulted in the
rapid increase in the deer population. They increased so rapidly that the range
could no longer support the large population, leading to the mass starvation of
the deer (Young 2002). The case study of the Kaibab Plateau helped to
facilitate a widespread change in opinion on the role of predators in
ecosystems. Ultimately, strategy shifted to predator management rather than
total predator eradication. Predator management involves manipulation of the
environment to favor the prey species by providing concealment from predators;
in some cases, lethal methods may be employed to target the predator.
It is important to note that predation
is a natural and vital part of any ecosystem. Game species, especially birds
such as quail and wild turkey (Meleagris
gallopavo), have evolved alongside their predators and have thus developed
attributes that allow them to successfully repopulate their community. For
example, Northern bobwhite (Colinus virginianus)
are capable of nesting multiple times during the breeding season and laying
large clutches of eggs; in addition, males often incubate the eggs while
females attempt to produce and incubate another nest (Smith 2010). The majority of quail and wild turkey predators
such as opossums (Didelphis virginiana),
skunks (Mephitis mephitis and Spilogale spp.), coyotes (Canis latrans), and grey foxes (Urocyon cinereoargenteus) are
generalists, meaning that they eat other things besides just wild turkey and
quail (Palmer “Predation Management”).
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| Raccoon (Procyon lotor) are one of the nest predators of wild turkeys and quail |
There are many ecological factors that
can make it appear as if predation has a larger impact on a prey population
than it actually does. The habitat may no longer support the prey population or
the habitat may have changed so that it favors the predator, rather than the
prey. For example, the presence of tall trees along fence lines can increase
predation, especially from avian predators, as it provides concealment to
ambush prey (Palmer “Predation Management).
Habitat manipulation is the first line of defense
against predation. The goal of habitat manipulation is to favor the prey
species by providing high quality habitable space across the landscape (Rollins
et al. 2004). Prescribed burning is a tool often utilized in quail and wild turkey management. However,
caution should be exercised when conducting burning, as burning large blocks
can increase predation (Palmer “Predation Management”). Perkins et al. (2014) found that under threat of raptor depredation, quail
flush and select denser shrubs for escape cover farther from the flush site.
However, under threat from nocturnal mammalian predators, quail flush shorter
distances and select less dense escape cover.
The differences in escape cover selection illustrate the need for vegetation
arranged in a patchwork; when large blocks are burned, quail are easier targets
for depredation because they are forced to find cover in small, concentrated
areas. When smaller blocks are burned, however, quail are able to find cover
over a larger area, thus reducing the potential of being found by a predator. |
| Avoid burning large blocks of available habitat, as this could increase the effect of predation. Small prescribed fires create a patchwork of desirable habitat. |
Predator management is cost effective
only if the landscape can support the additional game animals, which leads to
an increase profits, thus justifying the costs of predator management. In “Predator Control
as a Tool in Wildlife Management,”
Rollins et al. (2004) identified three questions that are important to ask before
implementing a predator management program:
- Is predation actually limiting local wildlife populations?
- Can the available habitat support a larger game population if predators are controlled?
- Will the surplus game produced as a result of predator management be used? That is, will harvest rates be increased to justify predator management?
If predator management can be justified,
habitat manipulation should be considered first to provide adequate escape
cover. In addition, cage traps, such as feral
hog traps, can be used to remove predators from the property.
Fencing can also be employed to restrict or funnel predator movement (Rollins
et al. 2004). Lethal methods such as foothold traps, snares, and
shooting can also be utilized.
 |
| A flowchart to help decide if predation management is the right tool to use (Schmidt 1978) |
Literature Cited
Smith,
Mark D. 2010. Controlling predators to increase quail populations. Alabama
Cooperative Extension System. ANR-1369.
Palmer,
Bill. Predation management and bobwhites. Tall Timbers Research Station.
Perkins,
Rebecca et al. 2014. Northern bobwhite predator avoidance behavior in response
to varying types of threat. The Journal of Wildlife Management 78: 1272-1281.
Rollins,
Dale et al. 2004. Predator control as a tool in wildlife management. Texas A&M
AgriLife Extension Service. B-6146.
Schmidt,
John L. and D.L. Gilbert. 1978. Big game of North America: ecology and
management. Stackpole Books, Mecahnicsburg, Pennsylvania, USA.
Young,
Christian C. 2002.In the absence of predators. University of Nebraska, Lincoln,
USA.