Weather, protein availability, and predation determine bobwhite quail population sizes
Each September, bobwhite hunters across the country wait impatiently for state wildlife agencies to publish their outlooks for the upcoming bobwhite quail season. A portion of these outlooks is determined by how many adult birds survived the previous winter. However, summertime bobwhite nest success and chick survival carry much more weight when deciding whether or not things look good for bobwhites.
A vast majority of regional bobwhite populations turn over annually. In some cases, annual turnover reaches up to 80 percent of the birds. Bobwhites and, therefore, bobwhite hunters depend on annual reproduction success to maintain and expand populations and hunting opportunities.
That said, what are the factors that drive bobwhite chick survival, and what can landowners do to give the little guys a boost in life?
Bobwhite Quail Chicks Are Vulnerable to Cool, Wet Conditions and Extreme Heat
Newly hatched quail chicks are precocial, meaning they can follow their parents to find food and shelter soon after they hatch. However, they are merely covered with a fluffy down and cannot thermoregulate effectively for their first couple weeks of life. Therefore, these youngsters depend on their parents to keep them dry and warm.
Excessive rainfall or an inability to find dry locations after heavy rain can take an awful toll on bobwhite chick survival. Parents try to keep the chicks dry via brooding or when adults cover their chicks with their wings. Brooding helps chicks maintain an optimal body temperature. However, chicks that cannot be effectively brooded or stay wet due to several hours of steady rain cannot maintain their body temperature. Often, these chicks die of exposure.
This phenomenon also occurs when broods are forced to be raised in areas of thick vegetation. Densely vegetated areas do not dry quickly or have enough space between plants to allow birds to reach dry areas. Research also shows that chicks with lower body temperatures consume less food, which puts additional stress on their little bodies.
One might find it hard to believe that quail chicks can die of hypothermia in late June or July when temperatures soar into the 90s. Remember, though, summer nights after a steady rain can get relatively cool. Featherless chicks that rely on their parents to help them maintain an optimal body temperature of 95 degrees can easily succumb to cool, wet conditions.
On the other end of the spectrum, summertime conditions can become so hot that chicks die from heat stress. This usually occurs in Oklahoma and Texas, where temperatures during the nesting season can reach 110 degrees or higher. When extreme heat occurs, quail broods seek shade in low-growing, shrubby plants, such as wild plums. If inadequate shrub colonies exist near brood locations, chicks can perish. That’s one of many reasons why it’s so important that quail have a well-distributed supply of shrubby cover in their home range.
Quail Chicks Need Protein Power
Quickly adding ounces and feathers is critical to chick survival. Bird feathers are made up of a particular protein called beta-keratin. For chicks to grow flight feathers quickly, they must obtain large amounts of this protein from their diet. For bobwhites, this means eating tons of insects and other invertebrates to gain weight and develop feathers.
Over 80 percent of a quail chick’s diet consists of invertebrates for the first couple weeks of its life. Invertebrate protein continues to make up a large percentage of their diet all summer. To a newly-hatched chick as tiny as a bumblebee, just about any invertebrate small enough to swallow makes a fine meal. From the tiniest spiders and leaf hoppers early in life to larger meals of grasshoppers and beetles as birds mature, invertebrate availability can make or break a region’s chick survival success. Areas high in insect diversity and availability create conditions where chicks can quickly grow flight feathers and gain weight, giving them a better chance to evade predators and be in optimum body condition come fall.
Not all habitats are created equal regarding their ability to produce insects. Areas with lots of broadleaved weeds and legumes attract many more invertebrates due to their high water content. The weeds must also be low to the ground so chicks can easily reach the bugs clinging to their leaves. These weedy areas must also be sparse enough to allow days-old chicks the freedom of movement. Young chicks have weak legs and cannot navigate thick, grassy areas. Sometimes, they get hung up and die as a result.
Broadleaved weeds also offer a canopy of protection from predators, providing chicks with easy access to escape covers and effective camouflage.
An author wrote once that “Quail are just born to die.” They meant that in all stages of a quail’s life, they are near the bottom of the food chain, and something is always looking to score a meal of bobwhite. Quail chicks are no exception.
Scientists have just recently been able to put radio transmitters on days-old bobwhite chicks. This gives us a much better understanding of chick ecology, including survival rates. Newly hatched bobwhites are very small and freeze for long periods when danger is near. This makes it harder for traditional quail predators like bobcats and raptors to catch them versus adult birds. On the other hand, snakes are very effective predators of young quail.
Snake species such as racers, rat snakes, and pit vipers can easily pick off individual brood members as they pass by. Research in Georgia has recently shown that some snake species have learned to actively follow broods around the landscape, snatching a chick here and there when they feel hungry. Additionally, the type of snakes that prey on chicks changes throughout the summer. Smaller snakes, like racers, are effective predators of very small birds, while rat snakes and other larger-bodied species take over as the birds mature.
Scientists don’t know what proportion of the chick population is taken by predators every year, but recent advances in transmitter technology should provide more answers in the future. One unique anecdote I read about recently was from researchers in the southeast. They recently tracked a juvenile quail transmitter to the stomach of a bullfrog; I guess all critters enjoy a meal of bobwhite as much as we hunters!
Shrubby cover versus tree cover also influences summertime chick mortality. I was involved in a recent research project in southwest Missouri that evaluated bobwhite chick survival in grassland landscapes. Where shrubby thickets, typically wild plum or dogwood, were well distributed across the landscape, chick survival increased. Where birds navigated to mature tree rows or timber edges, often due to the lack of shrubby thickets, survival decreased. Unfortunately, mature trees dominate the landscape across much of the bobwhite range. These areas harbor predators just waiting for an unsuspecting brood to venture past.
Landowners Can Help Support Bobwhite Quail Chick Survival
Weather events, particularly heavy rain and excessive heat, are the biggest factor in determining chick survival. We cannot do much about those two things. What landowners can do to help is create conditions where birds have the best chance of survival in poor weather conditions and have access to a diversity of invertebrates year-round. This includes creating large areas of broadleaved weeds, maintaining plenty of open spaces between plants, and providing adequate shrubby cover that is well-distributed. Folks that do not own land can advocate that local public lands are managed in a way that creates these conditions by pushing for increased prescribed burning and more ground disturbance.
Quail chicks have a tough life (apparently, even bullfrogs can be a problem!), and many do not survive to be a part of the fall population. But with favorable weather and greater attention to habitat management, there is always hope that those agency outlooks we look so forward to reading each September will be filled with good news.
Frank Loncarich has been a wildlife biologist for over 20 years, specializing in bobwhite and grassland management. He is also a Habitat Consultant for Land and Legacy.