The Wild Side: Cold weather may have affected game bird brood size this year
Wisconsin Department of Natural Resources employees are currently conducting the 10 week brood observation survey, which ends Aug. 17. While traveling during this timeframe, we document any upland game bird broods we observe, noting the date, the county, and number of birds. Upland game birds include pheasants, gray partridge, ruffed grouse, and turkey. The brood are the young birds hatched this year, referred to as chicks or poults.
All of these species are ground nesters, and their chicks are precocial, which means when they hatch they are covered with small fluffy feathers, they can see, and they are quickly able to leave the nest and walk behind their mother who leads them to look for food. Many other birds are altricial; when the babies first hatch, and for some time afterward, they are blind, naked (skin visible) and helpless; the parents have to bring food and drop it into their mouths in the nest. There are many examples of altricial birds-robins, mourning doves, eagles, and many other birds that build a nest off the ground.
The precocial nature of our game birds means they can often be seen at roadsides. These areas are often bathed in sunlight, mowed, and have lots of flowering plants. When you have flowering plants, you have insects, which are an important source of protein for chicks that need to achieve dramatic growth rates before fall and winter arrive. So, when we see what appears to be an attentive game bird standing by the road, we slow down and look in the grass to see if there are young birds around, and count the ones we can.
This year, I have seen fewer turkey broods than I normally expect; when I do see broods, there are only one or two poults with the hen. This is consistent with what other folks have reported seeing as well. Maybe this is a result of the late exit of winter, and the cool, wet spring. Being ground nesters, turkeys need bare ground to construct a viable nest. Typically, the hen lays one egg per day, stopping with a clutch of ten to twelve. She then sits on the nest to incubate the eggs, which usually takes about 28 days. The eggs are all incubated the same amount of time, meaning they should hatch at about the same time.
Could the cold weather have impacted nest hatching success? Possibly-if the ground was cold or frozen, and consequently not all the eggs incubated at the required temperature, they may not have hatched within hours of the best incubated eggs. This means any egg that didn’t hatch close to the beginning may not finish incubating. Once the first egg hatches, the clock is running. The brood needs to be prepared to follow the hen away from the nest within 12 to 24 hours. The chicks cannot last long without ingesting some kind of food.
The cool spring could also impact poult survival after hatching. Their primary food is insects, plus any seeds or berries they might find. In cold weather, insects are less active, if they are available at all. And, if plant growth is slowed because of a late spring, flowering plants are delayed in opening up, which means pollinators are less likely to be at ground level. If a chick or poult is unable to find enough food, it dies of starvation-its mother can only lead it to feeding areas, she does not feed them.
Chicks can also fall prey to any kind of predator. These young are very vulnerable from the time the egg is laid until the time the birds can fly, which is about two weeks after they hatch. Once they can fly, they can evade more predators and they can seek safety in the trees while roosting at night. Birds that reach this age have a good chance of surviving to adulthood.
Jeremy Holtz is a wildlife biologist with the Wisconsin DNR and writes a weekly column in the Star Journal. To contact him, call 715-365-8999.