Habitat Is Key For Game Birds of Idaho
Idaho is lucky to have an assortment of upland game birds, including sage-grouse, sharp-tailed grouse, chukar, gray partridge, pheasant, California quail and three forest grouse.
It is common for game bird populations to undergo dramatic changes in size, most often from annual variations in weather and habitat conditions. In healthy populations, even though numbers fluctuate wildly on an annual basis, the average size of the population remains remarkably stable over the long term. But when populations remain consistently low, managers are tasked with figuring out how to get back to desirable numbers.
Managing game birds, or any wildlife population for that matter, necessitates figuring out which "vital rates" limit population growth and which ones we can improve. Vital rate is scientific jargon for events in the life cycle of a species that affect the population. So for game birds that means things like nest survival, hen survival and brood survival.
Undoubtedly, predators have a major impact on these vital rates. Most nesting failures are caused by mammals, such as raccoons, fox, and skunks; adult hens are commonly killed by birds of prey; and chicks are consumed by mammals and predatory birds.
With this in mind, it's no surprise that reducing predator numbers is often offered as the "quick fix" to improve game bird populations. Seems like a no brainer, right? Well, maybe. Lucky for us, millions of dollars have been spent around the globe trying to figure out whether predator management actually works. The consensus answer is: "Sometimes, but not usually."
Actually, it depends on the management goal. If the goal is to pump out more pheasants for hunters to shoot in a small area, managing predator numbers can be effective. But if it is trying to turn around a long-term population decline over a large geographic area for a species in trouble, say like sage-grouse, predator management likely won't result in any measurable improvements.
It all comes down to which vital rates we can affect. Reducing mammalian predators may result in more eggs hatching and more chicks living long enough to provide hunting opportunities.
However, for legal, logistical and ethical reasons managers are unable to control predatory bird populations that have a major impact on hen survival, which in turn limits the ability of managers to improve the number of hens pumping out chicks the following spring.
Predator management is not cheap, nor is it a one-time fix. Even in instances in which it was documented to be beneficial, researchers are quick to point out that professional dedicated trappers must be hired, and there are no long-term positive effects of predator management. It must be done year after year, because as soon as you remove a few predators from an area, a few more are waiting to fill in the now vacant territory of his or her neighbor. And most predators ramp up their own reproductive effort when their populations are reduced.
Nor should it come as a surprise to anyone living in Idaho that reducing the population of a predator to improve the population of another species can be a contentious and hotly debated issue in the court of public opinion.
Simply put, using predator management for game bird production is a Band-Aid approach to deal with a persistent underlying problem. Impaired habitat is the gaping wound that won't go away, no matter how many Band-Aids you put on it.
Habitat is the foundation for healthy game bird populations.
Increased and intensified agriculture, urban sprawl, increased fire in sagebrush habitats and the spread of invasive plants are just a few of the causes for game bird habitat alteration and reduction in Idaho.
Obviously, loss of habitat results in fewer places for game birds to live. But just as important is the relationship between habitat loss and predator efficiency. Finding a nest, chick or hen in large expanses of quality habitat is like finding a needle in a haystack. Reducing habitat is analogous to putting thousands of needles in half a bale's worth of hay.
Less habitat in smaller patches concentrates hens, nests and broods, which is good news for predators and not so great news for game birds. The best approach for improving game bird populations is to improve, expand and create habitats that game birds and a variety of other wildlife depend on. If we can do that, the predator problem most often takes care of itself.
Matt Pieron is a regional wildlife habitat biologist in the Clearwater Region.