Brood Over This: Poult and Brood Habitat Chat with Mark Hatfield, NWTF Senior Wildlife Biologist
Last week, we asked NWTF members to submit their questions about wild turkey poults and brood habitat, and had a great response. Read on to learn everything you need to know about poults, habitat and more.
Q: I flushed a hen off a nest yesterday. There were 12 eggs in the nest. Considering that was July 10, how long is the nesting period and when would that hen had to have mated? I thought it was too late in the year for nesting.
— William Griffin, Easley, S.C.
A: A single breeding from a gobbler can fertilize all the eggs in a clutch and can even last through a re-nesting attempt. A hen may lay fertile eggs up to four weeks after mating even though she may be bred by toms every day during the laying. Hens will lay an average of 10 to12 eggs per clutch, which takes about two weeks. Laying behavior is variable and some hens are able to delay laying in response to disturbance or unusual weather conditions. Incubation will not start until the hen has completed laying her clutch and will last 25 to 29 days. So for this example, depending on the age of the eggs, the hen could have initiated her nest anywhere between May 30 and June 27. These dates are out of the peak nesting period for your area but wild turkey hens will often re-nest if they abandon their first nesting attempt, or if predators disturb the nest.
Q: We have seen some terrible rains from late May through mid-June and no poults yet; how does the rain affect wild turkey poults?
— Charlie Nichols, Cross Lanes, W.Va.
A: Most biologists commonly analyze current and past weather conditions to better understand weather influences on hunting success, harvests, reproduction, survival and, ultimately, even population numbers. The most devastating impact of weather on wild turkeys occurs during the nesting and brood-rearing period in May and June.
Biologists have 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 and June. If precipitation is high, the fall turkey population and harvest are down. A decline in May and June 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 the scent from hens with wet feathers is easier to detect than the scent from hens with dry feathers.
Weather not only affects nesting success, it also can have a devastating impact on poult survival. Weather combined with predation is largely the reason that 50 percent or more of young poults are lost during the first two weeks after hatching. Research has shown that a combination of low temperatures (45 to 52 degrees) and rain for more than 12 hours can cause the death of young turkey poults.
Q: I was told this past spring that hens nest or lay eggs on a 25-hour cycle. Basically, a hen will go to nest and lay one egg an hour later each day and can potentially lay for up to 12 days. With her first egg being laid at 9 a.m. on the first day she could potentially being laying her last egg 9 p.m. on the last day. What truth is there to this?
— Anthony Wade Smith, Ten Mile, Tenn.
A: The average full clutch of an adult wild turkey hen is 10 to 12 eggs, and it takes approximately two weeks for a hen to complete laying a clutch. Laying behavior is variable and most hens lay one egg per day — usually in the middle of the day. But hens are able to delay laying in response to disturbances or unusual weather conditions.
Q: I have worked a great deal with sage grouse and was accustomed to nests being wiped out by predators. If the eggs hatched and the birds survived, they then had to battle to stay alive by avoiding the same predators. I have been wondering what the average survival rate is on a clutch of Rio Grande eggs and what age the chicks need to attain, on average, to survive their first year.
— Harry A. Barber, Kanab, Utah
A: Turkey nests are no different then sage grouse nests. Both types of nests and poults have a high number of diverse predators that often overlap. These predators include but are not limited to raccoons, coyotes, bobcats, foxes, skunks, hawks, eagles, owls and even snakes. It is a safe assumption that about half of all nests are lost to either abandonment or predation and more then half of all poults die within two weeks of hatching, mostly due to predation. Poult survival increases once the poults are able to fly up to a roost each night.
Q: Trying to figure out the different phases of the breeding cycle of a wild turkey for your area with factors like weather, etc., is tough enough, but my question is: Once a turkey hen has been bred, how long will it take her to lay the first egg? According to Lovett Williams' studies of egg laying behavior, with this knowledge, I should be able to figure when that hen will be "setting" and thus know approximately when most hens will be on the nest and Old Wily Longbeard will be looking for some action.
— Douglas Mallory, Niceville, Fla.
A: A gobbler can fertilize all the eggs in a clutch in a single breeding, and can even last through a re-nesting attempt. Although a hen may be bred by toms every day during the time she is laying a clutch, the hen can lay fertile eggs up to four weeks after mating. But several variables affect the laying process. The major variables include the increased length in the photo period (longer days equal more sunlight), and by the inborn cycle of certain endocrine glands. Other factors that may stimulate or delay egg laying include weather, diet, age and disease. Light indirectly activates both male and female reproductive organs by stimulating the anterior pituitary through the nervous system.
That being said, a more concise way to determine peak nesting and to pinpoint when gobbling activity will be the highest is to determine the average nest initiation date. For example, once you observe a hen with poults, determine their age as accurately as you can. Assume there is a 25- to 29-day incubation period and subtract that period (age plus incubation) from the observation date to determine when the hens began sitting on nest, thus increasing gobbler activity.
Turkey eggs are normally developed in a very orderly process. The yolk (ovum) is released into the body cavity from the ovary and the upper end of the oviduct (the infundibulum) picks up the yolk and the rest of the egg is added as the egg moves down the oviduct. The white or albumen is added in the magnum portion of the oviduct. The shell membranes are added in the isthmus, and the shell is placed on the egg in the uterus. Spots and shell color are also added to the egg in the uterus. From start to finish, it takes 24 to 30 hours for a turkey to produce one fertilized egg.
Q: Will a wild turkey hen sit on a nest of infertile eggs? We have a wild turkey hen sitting on 10 eggs in the field next door. She seems to have been sitting there a long time. If a hen was not impregnated or is sterile (if that's possible), would she still sit on the eggs for an indefinite amount of time?
— Gerry Linneweh, Hamilton, Mont.
A: Yes, a hen will sit on a nest that is infertile, but she will ultimately abandon the nest attempt. Studies have shown that 95 percent of all eggs are fertile in the first nesting attempt with only a slight decline in fertility for the second nesting attempt. It is rare that a hen will lay infertile eggs, but when it happens, it could be due to a shortage of breeding gobblers , or, most commonly is attributed to weather and nutrition. Don't forget that the incubation period ranges from 25 to 29 days in length.
Q: Various insects and reptiles can reproduce via parthenogenesis where embryos develop without having been fertilized by a male. I have read that, rarely, domestic turkeys have been known to reproduce in this manner. Can wild turkeys produce poults via parthenogenesis? If so, what triggers this and approximately how often might this occur?
— Charles C. DeRamus, Prattville, Ala.
A: You are correct that parthenogenesis has been documented in domesticated turkeys, but it has not been documented in wild turkeys. Parthenogenesis — reproduction without the benefit of sex — occurs spontaneously in a handful of species, most of them fairly simple but some surprisingly complex. It is more common in invertebrate species like water fleas, aphids, some bees, and some scorpion species, than in vertebrates species such as some reptiles, fish, very rarely birds and sharks.
