Robin C. writes: Something I wonder about is the predator-prey chain here in Cambridge. Who is eating the turkeys? Why are turkeys thriving?
These are very good questions.
Who eats wild turkeys?
Let’s start with turkey predators. Adult turkeys don’t have many predators because they are big and aggressive. They can run quickly and fly into trees to escape.
However, coyotes may kill nesting females or chicks, called poults, which cannot yet fly, and great horned owls can take adult turkeys at night when they are roosting in trees.
Other predators— snakes, raccoons, skunks, opossums and foxes — eat turkey eggs or poults.
Female turkeys build nests on the ground, so it is not surprising to learn that female turkeys are most likely to be killed at night while they are nesting. The female incubates her eggs for about four weeks. This is a long period of egg vulnerability, but if predators destroy the first batch of eggs, the female may lay a second batch in a different spot.
Female turkeys lay large numbers of eggs — up to 15 at a time. Unlike many other species of birds, from robins and wrens to crows and woodpeckers, turkey chicks are not helpless when hatched. They leave the nest within hours. At night they huddle together on the ground beneath Mama Turkey’s wings and tail to stay warm. On the ground, they peck at insects, which make up most of their diet in these first days. After about two weeks, their wing feathers develop and they can fly into a tree to roost at night. But despite their robustness, 76% of turkey poults do not survive the first two weeks. Once they can fly, their chances of survival greatly increase.
Why are turkeys thriving?
In the 1600s, wild turkeys were common in New England. In 1634, William Wood wrote that turkeys can “run as fast as a Dogge, and fly as well as a Goose.” They gathered in large flocks: “Sometimes there will be forty, threescore, and a hundred of a flock.” He even describes how easy they were to hunt. After a new snow, “follow them by their tracts; some have killed ten or a dozen in half a day.” If a hunter can find where they roost at night, at around 10 or 11 p.m., a hunter may “shoot as often as he will,” as the birds will just sit in the trees.
Little wonder that by the 1700s, turkeys had become less plentiful. In Northampton in 1717, dressed turkeys cost 16 pence each. (There were 12 pence in a shilling and 20 shillings in a pound, if this helps.) Suffice it to say that this was about one-third to one-half of a laborer’s daily wages.
By the mid-1800s, turkeys had disappeared from Massachusetts altogether due to hunting and cutting down forests. In the 1970s, however, wildlife biologists reintroduced turkeys to Massachusetts. These birds spread throughout the state and thrived because the state now regulates hunting, some forests have returned and turkeys find plenty of food.
Suburbs provide food, shelter and nesting sites. There are no hunters lurking in the bushes. Suburbs are similar to the mixture of forests and open spaces that turkeys naturally look for.
What do turkeys eat?
In 1825, writing about an earlier time when turkeys were abundant, French-American ornithologist Charles Lucien Bonaparte (nephew of Napoleon Bonaparte) wrote: “The Wild Turkeys do not confine themselves to any particular food; they eat maize, all sorts of berries, fruits, grasses, beetles. Even tadpoles, young frogs, and lizards, are occasionally found in their crops. . . . Their more general predilection is, however, for the acorn, on which they rapidly fatten. … About the beginning of October, they assemble in flocks.” According to Bonaparte, Indigenous people called this time of year “ Turkey month.”
How do turkeys survive the winter?
Turkeys do not migrate. But they have dense plumage to help them stay warm in winter. Their feathers trap air, reducing heat loss. When it gets cold, they fluff their feathers to reduce heat loss even more. Their strong claws help them scratch for nuts and seeds under leaves and beneath light snow cover. However, deep snow is a problem for them, as it makes it difficult for turkeys to walk or fly. If snow is crusty or icy, they may not be able to claw through it to get to food on the ground. When turkeys cannot search for food, they roost in trees and rely on stored body fat until conditions improve. A wild turkey can live up to two weeks without food.
If deep snow lasts for a long time, however, turkeys starve and die. Research has shown that snow deeper than about a foot interferes with turkeys’ ability to survive. In one study, researchers used radio-telemetry to track 181 wild turkeys for four years. They found that winter survival rates declined dramatically when snow was deeper than 12 inches for more than 10 days. Cold temperatures also reduced survival. In the spring, rainfall affected both egg and chick survival.
Do warmer, less snowy winters help Massachusetts turkeys survive? My guess would be yes. This leads back to Robin’s original food-chain question. If more turkeys survive, does that mean more turkey predators — coyotes and owls —do, too?
Coyote populations are stable, and great horned owls have expanded their range in Massachusetts. Turkeys, though, make up only a small portion of the owl’s diet, which also includes rabbits, rodents, skunks and birds. So the great horned owl expansion is a topic to explore another day.
A stronger
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