The wild turkey has pulled off a stunning comeback in Wisconsin – but has the turkey”s success come at the expense of local grouse populations? That question has been muted a bit this year as the 10-year grouse cycle approaches its peak, but it often arises when turkeys move in. It was especially common when grouse numbers bottomed out earlier this decade.
While you can find newly arrived turkeys in former grouse-only woods, the birds” differing habits and food preferences ensure that neither is likely to displace the other, according to Scott Lutz, a wildlife ecologist at the University of Wisconsin-Madison”s College of Agricultural and Life Sciences.
A species that”s expanding its range can hurt an established species by preying on it or out-competing it for food and habitat. Damage generally occurs when exotic species invade new territory. It rarely happens with species – turkeys and grouse, for example – that have historically co-existed, Lutz points out.
Turkeys don”t eat grouse, which rules out predation. While they share some foods, wild turkeys aren”t likely to starve out local grouse. Here”s a look at some of their food choices through the year:
In late spring and through the summer, newly hatched grouse and turkeys eat insects – lots of them. The youngsters instinctively peck at moving things – which are usually protein-rich bugs or larvae. As you know, Wisconsin has no shortage of summertime insects. Baby birds aren”t afraid to look around for their dinner – one study found grouse chicks a half-mile from their nest site a day after hatching. Adult turkeys prefer grass and other plant leaves, along with berries and bugs. Adult grouse go for the leaves, fruits and seeds of aspens, along with berries and greens.
In the fall, grouse feed on aspens, acorns and berries; turkeys prefer grass seeds and acorns, hazel nuts, walnuts and hickory nuts.
Acorn consumption in perspective: Deer, grouse and turkeys (along with squirrels, wood ducks, and a lot of other animals) all eat acorns. When you consider the acorns eaten by a 1.5-pound grouse versus a 15-pound turkey versus a 150-pound deer, turkeys aren”t the major factor in acorn disappearance. Grouse don”t build up fat reserves before winter, so they”re not affected if turkeys or deer eat up all the acorns in the fall, when plenty of other food is available. In typical northern winters, remaining acorns are buried under the snow and not a factor in grouse diets.
Winter is crunch time. Grouse generally feed twice a day on aspen buds and other buds, twigs and catkins up in the trees; turkeys prefer to scratch on the ground for acorns and other seeds and nuts. Grouse are better adapted to Wisconsin winters than turkeys, but where turkeys can fuel up on farm-field leftovers, they handle winters pretty well.
In spring, grouse return to the ground to feed on the leaves and shoots of new plant growth. Turkeys feed on mast crops (acorns and other nuts) and leaves.
Turkeys aren”t finicky eaters – they”ll consume waste grains and aren”t above picking pass-through corn out of cowpies. Grouse in northern Wisconsin are pretty tied to aspen leaves and buds, Lutz points out. Turkeys show little interest in aspen buds – the mainstay of the grouse diet.
While turkeys and grouse may occupy the same areas, they don”t get in each other”s faces. Turkeys like edge habitat and a mix of cover types. Old grassy farm fields, small blocks of hardwoods with a lot of edges, and mixes of woods/cornfields, woods/hayfields, and woods/pasture suit them fine. Grouse prefer disturbances in woody habitat that create early succession – for example, young aspen stands, or brushy openings that follow disturbances in oak/hickory forests. They prefer shrub/tree edges, but will also use field and road edges. “In the same piece of land, grouse will be in the brushy areas, turkeys at the edges, with some overlap,” Lutz says.
Turkeys and grouse share some parasites and diseases, but Lutz and most other wildlife researchers believe diseases have little overall effect on wildlife populations. Since turkeys and grouse have lived together in the past, turkeys aren”t likely to introduce epidemics that wipe out local grouse when the big birds move back into grouse strongholds .
If you”re looking for causes of grouse declines, likely culprits include development of habitat and maturing forests. Grouse coverts that become golf courses produce no more grouse. Grouse thrive in areas with young aspens and tall shrubs, where they find food and shelter. Mature trees reduce ground shelter by shading out understory shrubs. With fewer stems per acre than young forests, mature forests provide little vertical shelter from flying predators.
“It”s reasonable for people to propose alternative explanations for the lows – especially when you have highly visible turkeys successfully establishing themselves in grouse country,” Lutz says. “Turkeys have surprised a lot of people, including wildlife managers, with their adaptability and how they can extend their range.”
Good news from drumming counts should keep grouse enthusiasts smiling for the next few years, and the Minocqua/Woodruff area is a good recent example of peaceful coexistence. Turkeys were moving into the area last year, but this year, grouse counts are up despite the newcomers.
Lutz has studied turkeys in Kansas, Texas and Oregon. His current research at UW-Madison focuses on the ecology and management of quail, turkeys, woodcock, songbirds, magpies, and the threatened piping plover. He teaches Population Dynamics and Wildlife Investigational Techniques in the Department of Wildlife Ecology and serves as a Fellow at Chadbourne Residential College.