With nearly six months until friends and family gather to partake in the traditional opening day hunt, pheasants are one of the last things sportsmen are thinking about during spring. However, the nesting and brood-rearing season of May and June represent one of the most critical times for pheasant populations.
Pheasants are short lived birds with annual survival averaging only 50%. During severe winters such as 2009-2010, survival can be much lower in areas containing marginal or inadequate winter habitat. With such low survival, how do pheasants sustain such high populations each fall? Of all upland game birds, pheasants exhibit one of the highest reproductive potentials, thus enabling them to bounce back after severe losses in short time periods when provided adequate nesting habitat. Despite this, pheasants still rely on quality nesting and brood rearing habitat to recruit new birds to the fall population.
The nesting season begins in late April as hens seek out attractive nesting cover usually consisting of undisturbed grasslands such as lands enrolled in the Conservation Reserve Program (CRP). Most hens initiate their first nest during the first half of May, but this can be delayed by unseasonably cold or wet weather. Males have spent the past month establishing and maintaining territories across the landscape. Crowing and wing flapping behavior aimed at attracting females peaks in April but continues through June to serve re-nesting hens.
After courtship, hens lay one egg per day until a full clutch of 10-12 eggs is reached. During the next 23 days, hens will spend 23 hours per day incubating the eggs and leaving for only short intervals for limited amounts of food and water. Egg laying and incubation is extremely energy demanding, and during incubation food intake is low. Hens can lose 75% of their body fat and 10% of their body weight in just one month! If not challenging enough, only about 25% of nests are successful in large blocks of undisturbed grasslands and success has been documented much lower in linear and fragmented habitats which are generally smaller in size.
Fortunately, pheasants almost always re-nest and may initiate up to 4 nests in a single season if previous nests are destroyed. Because of the energy demands of producing and incubating eggs, clutch size and egg size decrease for each subsequent nesting attempt. If a third nesting attempt is initiated, the clutch size could be as low as 5 or 6 eggs. Even with low success of each individual nest, 70% of hens may pull off one successful nest through multiple nesting attempts.
Hatching a successful clutch is only half the battle to recruit pheasants to the fall population. Pheasant chicks are precocial, meaning they hatch with eyes open and are able to leave the nest and feed themselves within one day of hatching. However, it has been documented that 1 and 2 day old chicks exposed to 43 degree temperatures die after 30 minutes of exposure. Susceptibility to the cold quickly decreases with age, and by 11 days of age the chicks can fully regulate their body temperature. Cold snaps in June can greatly decrease chick survival.
As stated earlier, most pheasants nest in grasslands such as land enrolled in CRP. But does this same habitat provide for the needs of pheasant chicks? This depends on the structure and composition of the grassland. Ideal brood-rearing habitat provides abundant insects, aerial concealment, and allows movement at ground level by small pheasant chicks. The average grass field which has not been disturbed recently does not meet these criteria. Can you imagine a tennis ball sized pheasant chick navigating through thick seven foot tall grass that your Labrador struggles to get through in the fall!
Pheasant chicks primarily eat insects during the first 1-2 weeks of life because they are high in protein. Protein functions as building blocks to form muscle tissue and feathers which allows for rapid chick growth. Without plentiful insects, growth rates and survival of chicks can be greatly reduced. Hen pheasants will often move her brood great distances to find suitable brooding habitat such as “weedy” areas. Broadleaf plants act like insect factories, while also providing aerial concealment without impeding chick movement at ground level. Aerial concealment protects chicks from aerial predators and provides shade during those hot summer days. Even when good habitat is available, it is not uncommon for 1/3 of the chicks to die with predators, extreme weather, and farm machinery representing the highest mortality factors.
South Dakota is fortunate to have an abundance of high quality nesting and brood-rearing habitat which allows pheasants to reach their high reproductive potential. As you head to the field each year, remember that what pheasants were doing in May and June has a huge influence on what you will see each fall.