They're Up... They're Down

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Published on: Jul. 2, 2000

Last revision: Nov. 5, 2010

this recovery.

Harvest also affects Canada goose populations, but not all populations are affected equally. For example, giant Canada geese, which nest in Missouri, rarely experience a poor production season, and because they don't migrate as far as other species, they are exposed to hunting less. They typically survive at a high rate, so hunting regulations for giant Canada geese often are liberal.

In contrast, the Canada geese that nest near Hudson Bay migrate 1,500 miles to Missouri and must run a gauntlet of hunters in Manitoba, Minnesota, South Dakota and Iowa before they arrive. More are taken in Illinois and Arkansas after they leave Missouri.

Additionally, the timing of the spring thaw on northern breeding grounds strongly influences the nesting success of Canada geese. If nesting is delayed past early June, few young geese are added to the population. This "bust" in production occurs about once every 10 years.

Overharvest in these years is devastating because too many breeding-age birds (more than 3 years of age) are harvested, and it takes a few years after the next good nesting season for the breeding population to rebuild. Low harvest and good production both are required for populations to recover.

Most hunters agree with waterfowl hunting restrictions when habitat conditions and population levels dictate. However, they frequently disagree about the timing of the seasons. For example, many goose hunters prefer later seasons that coincide with the arrival of northern geese rather than early seasons scheduled primarily for geese breeding in Missouri.

Likewise, some duck hunters want an early season because they hunt primarily in shallow marshes; other duck hunters want a late season so that freezing water will concentrate birds into open water areas. We try to respond to hunters' preferences as well as biological considerations when we set waterfowl regulations.

Turkeys

The restoration of wild turkeys in Missouri began in the mid 1950s. After initial releases, local populations grew exponentially for the next 20 to 25 years. Closed or restrictive seasons were essential during that period until populations became self-sustaining.

Rapid population growth followed by fluctuating numbers is typical of reintroduced populations. We do not fully understand why this pattern occurs as population densities increase; however, factors such as predation and social interaction among individuals probably play a big role.

Now that turkeys are established in Missouri, their population changes primarily are determined by summer nesting success and recruitment, which in turn are influenced by spring and summer weather conditions. An early spring seems to be associated with higher nesting success, and dry weather during early June results in higher poult survival.

Nest predation may influence nest success, but wild turkeys can produce many young despite high levels of nest predators. Winter conditions generally have little influence on wild turkey population dynamics; however, the availability of winter food in the eastern Ozarks (acorns) can affect nesting success during the breeding season that follows.

Spring and fall wild turkey regulations have different purposes. The primary purpose of spring regulations is to maintain the quality of spring turkey hunting. Spring regulations have little to do with whether turkey populations grow or not. In contrast, fall regulations are set conservatively to minimally impact the population.

Gobblers are important to spring turkey hunters. Thus, hunting regulations for the spring season are primarily set to ensure that less than 35 percent of the male population is harvested. Because only males are killed in the spring (except for a few bearded hens, which are legally taken) and one male will mate with several hens, the harvest has little or no impact on the potential for population growth.

Fall turkey regulations are set to ensure that wild turkeys are not overexploited. A harvest of less than 10 percent of the fall population has little impact on population growth. Because reproduction varies considerably, however, we have maintained a conservative approach to fall turkey seasons. Under current regulations and hunting pressure, less than 3 percent of the fall population is harvested. There is no reason to believe that the fall harvest of turkeys in Missouri affects the numbers of birds available the following spring or the quality of spring hunting.

Hunting regulations help ensure that populations are not overexploited. Wildlife populations change over time, usually prompting renewed scrutiny and possible readjustment of current regulations.

Biologists continue to track numbers, production, habitat conditions, harvest and hunter attitudes. We use this information to recommend seasons that are stable and simple when possible, and we change regulations when necessary to balance species' biology with harvest and hunter preferences.

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