How Weather Affects Turkey Hunting
By Jim Pack
Weather has been defined as the short-term changes in temperature, precipitation, wind speed, and other atmospheric conditions. A turkey hunter caught in a cold rain without any rain gear does not need a definition of bad weather, and he probably doesn't care to have anyone tell him how important weather is to turkey hunting and turkey hunting success.
Consequences of bad weather to him may be a cold, an unsuccessful hunt, and maybe even a rusted gun if he forgets to clean it. To wildlife biologists and managers, weather can have a far greater impact than the moment at hand. Biologists commonly analyze current and past weather conditions. Some of their findings may be useful to hunters and allow them to better understand weather influences on hunting success, harvests, reproduction, survival and ultimately even population numbers.
Hunters participating in West Virginia's spring gobbler survey have provided weather information to biologists for 18 years, and it is evident that the best spring gobbling occurs during clear days with little wind and no precipitation. Conversely, periods of reduced gobbling activity coincide with cloudy skies, rain and windy conditions. Research elsewhere on the relationship between gobbling and weather has shown that precipitation and high wind occurring as much as 12 hours prior to the time of gobbling will result in decreased gobbling. One Alabama study showed that days with dew on the ground were good gobbling days, and that barometric pressure had little impact on gobbling although it is a part of the reason for changes in weather patterns.
The relationship between gobbling and temperatures is not as definitive. One research study indicated increased gobbling occurred with higher temperatures, and another did not show any relationship between temperature and gobbling.
Biologists have learned that weather can have a major impact on harvests, especially when inclement weather occurs during the period when most hunters are afield such as the first few of days of the season and on weekends. One doesn't need to be a rocket scientist to know that if hunters are not hunting or cannot hear gobblers because of high winds and rain, the harvest will likely be lower than when the weather is pleasant.
The most devastating impact of weather on wild turkeys occurs during the nesting and brood-rearing period in May and June. Nearly four decades ago, West Virginia biologists learned of an unusual relationship between fall turkey harvests and temperature. Results indicated that the more the May weather departed from normal in regard to temperature and precipitation, the lower the wild turkey harvests would be during the fall hunting season.
More recently, biologists in New York have expanded this research. They determined that the annual change in wild turkey populations is largely related to nesting success that year, and nesting success is directly related to precipitation during May. If May precipitation is high, the fall turkey population and harvest are down. A decline in May precipitation means higher fall harvests. May is the period when hens are laying and incubating eggs.
Biologists have theorized that when rainfall is abundant during this month, scent conditions make it easier for predators to locate hens on nests. This is referred to as the “wet hen theory” because it is hypothesized that scent from hens with wet feathers are more detectable than those that are dry.
Not only does weather affect nesting success, it can also have a devastating impact on chick survival. Weather in combination with predation is largely the reason 50 percent or more of young chicks are lost during the first two weeks after hatching. Researchers in West Virginia have learned that a combination of low temperatures (45-52 degrees) and rain for more than 12 hours can cause the death of young turkey poults .
Catastrophic weather conditions such as hurricanes and floods occurring during the early brood-rearing period have also been documented to have devastating effects on young turkeys. When Hurricane Agnes came through West Virginia in June 1972 with precipitation levels more than twice the norm, production of young turkeys dropped drastically. Few poults that hatched after the first of June survived that year.
Poult counts in neighboring Pennsylvania where over 18 inches of rain fell resulted in field personnel observing only one-third as many broods as the previous year.
Hurricanes may also cause severe long-term alteration of wild turkey habitat. For example, Hurricane Hugo had a devastating effect on millions of acres of habitat in South Carolina by uprooting or damaging trees. This destruction in habitat ultimately caused a decline in the wild turkey population.
Winter weather conditions such as powdery snow at least 12 inches deep or more deep lying on the ground for several weeks and cold temperatures will increase mortality and predation during the winter months. Fortunately this phenomenon is rare in West Virginia because the temperature commonly rises sufficiently after snowfall to cause the snow to crust so turkeys can walk to spring seeps or areas where they can scratch through the snow to food. Winter losses, however, do occasionally occur in our Eastern Highlands.
Biologists documented in 1993 the combined effect of deep snow and a shortage of food on wild turkey hens by determining survival of hens equipped with radio transmitters. A mast failure was observed during the fall of 1992, leaving little food for turkeys and other animals in our highlands during the winter of 1992-93. In late March 1993, blizzard conditions occurred and caused lower survival of turkeys here compared to the rest of the state. Birds were already in poor physical condition, and the blizzard created conditions intolerable for the weakened birds.
Weather has a significant impact on the availability of wild turkey foods. If atmospheric conditions in the spring are not suitable during the flowering period of our mast-producing trees and shrubs, the entire fall mast crop may fail. These mast failures have occurred at five- to eight-year intervals in West Virginia since 1970.
Freezing temperatures are not the only cause of poor mast crops. Wind, prolonged rain, relative humidity, and temperatures have been shown to affect the opening and closing of the anthers and dissemination of pollen. One study in Pennsylvania showed that abundant white oak acorn crops were produced only when a warm 10-day period in late April was followed by a cool period in May.
As we go from the fairly simple notion of weather affecting a hunter and his success, to the complicated relationship of weather impacts on wild turkey populations and habitat, it illustrates the many processes over which we have little control. It is important that hunters and wildlife managers understand this.
While it means that there are limits to what we can do in management, it is still interesting and worthwhile knowledge which allows hunters to comprehend why their hunting success varies and why some wildlife populations change from one year to the next.
Jim Pack is a research wildlife biologist stationed in Elkins.