October Wisconsin Nature Notes
In October, loons and turkey vultures begin their remarkable migrations; elk bugle and seeds are on the move.
UNRAVELING THE MYSTERIES OF LOON MIGRATION
Adult common loons leave their breeding areas in late October, headed for the Gulf of Mexico and the Atlantic coast. Several decades ago, little was understood about when loons left on their migration, where their migratory routes took them, and where they spent their winters. But since 1991, researchers in northern Wisconsin have banded more than 3,600 adult loons and chicks, providing a wealth of information on their behaviors. A much smaller number have also had satellite radio transmitters surgically implanted in them, allowing biologists to accurately track their daily movements.
What they’ve learned is that most of Wisconsin’s adult loons winter up to 80 miles offshore of northern Florida, a distance of between 1,170 to 1,570 miles from their breeding lakes. The adults typically first fly east to Lake Michigan to waters off Door County and spend a week or more there. They then typically work their way down to waters off southern Lake Michigan before taking their next migratory hop to inland reservoirs in Kentucky and Tennessee, and then on to the Gulf of Mexico. In one documented case, a loon traveled 670 miles within a 24-hour period. But most seem to take their time, resting for days at stopover sites along the way.
The stopover sites that loons utilize are of great concern to biologists because low lake levels and aquatic invasive species in the Great Lakes have spurred a rise of botulism E, which has infected fish that the loons eat, often then sickening and killing the loons. During the 2012 fall migration, 1,500 dead loons were recovered from Lake Michigan.
In 2014, researchers captured and implanted transmitters in juvenile common loons on lakes scattered across Minnesota and Wisconsin. Juvenile loons don’t return to the breeding grounds until they are from 2 to 5 years old, and very little has been known about their movements, habitat use, and the causes of their mortality during their first few years.
Initial results show the juvenile loons are moving from the Gulf of Mexico to the Atlantic coastline and then northward. As of August 2015, three juveniles had wandered all the way up to the coastlines of Nova Scotia and News Brunswick. Scientists are speculating that the cooler northern waters offer a better fishery.
Wisconsin has an estimated summer population of about 4,300 adults. As an iconic bird of the Northwoods, knowing as much science as we can about their migration will help us not only further appreciate them, but also help them thrive.
BUGLING ELK AIM TO INTIMIDATE
An autumn concert put on by a bugling bull elk is truly memorable. Beginning in early September and ending late in October, a bull typically gathers a harem of 10 cow elk for breeding, and then defends his entourage by bugling to intimidate his competitors. You'd expect an 850-pound animal, five times the size of a large white-tailed deer, to make a deep, resounding bellow when it bugles, particularly to defend that many females. But not so. The sound ranges from deep tones, to high-pitch squeals, to grunts and has been variously described as a “low wheezing, almost asthmatic whistle that ends in a series of evil-sounding grunts,” and as “a shrill shriek descending the scale into a blasting bawl.” In other words, you have to hear it for yourself.
In Wisconsin, the last elk was shot in 1866. Though never common, historic records show elk once inhabited 50 of the state's 72 counties. In 1995, 25 elk – 18 females and 7 males – were captured in the Upper Peninsula of Michigan and released near Clam Lake, east of Hayward in the Chequamegon National Forest. This area was specifically chosen because it fits the general habitat requirements of elk – forests interspersed with openings, brush land and grassland. The Clam Lake area was the site of the U.S. Navy’s Extremely Low Frequency communications project – Project ELF – that was located there in 1982. Although this system was shut down by the Navy in 2004, the forest openings are maintained through partnerships, providing an expansive open habitat for the elk.
As of 2018, elk are grouped in two herds near Clam Lake and Black River Falls. The goal is 1,400 elk for the Clam Lake Range and 390 for the Black River Range.
For the best chance of hearing a bugling elk, go out in the pre-dawn dark to viewing areas recommended by the Wisconsin DNR and U.S. Forest Service near Clam Lake. With luck you may get to hear a low whistle that rises several octaves and ends in a deep growl. It’s a sound you’ll never forget!
SEEDS SEEK NEW WORLDS IN AUTUMN
In October, most of the plant world is shutting down ahead of a long winter, but simultaneously, many plants are also seeking new worlds by sending out their seeds. To help the seeds travel as far as possible, plants utilize an amazing array of strategies. Some, like the black cherry, put a final gift wrap over the seeds, something bright, colorful and sweet-tasting to encourage transport by way of digestive systems. Other plants like thistle choose to make their seeds sticky or bristly in order to hitch a ride to another town. Some create an aerodynamic appendage, like a milkweed’s silk parachute or a sugar maple’s winged helicopter. Still others coat their seeds in a waterproof jacket that acts like a PFD, floating the embryo down river to rest on a shoreline.
Once in their new world, the seeds have sensors that will respond to the right combination of temperature, light, oxygen and moisture to initiate growth. If the conditions aren’t perfect, the seeds may not germinate for years. The record for patience may be ten thousand-year-old lupine seeds, which were found in 1954, and then placed on wet filter paper where six seeds germinated within 48 hours. One plant, upon reaching 11 months of age, and after 10,000 years of dormancy, bloomed.
Timing is everything in the dispersal of seeds. Red oaks, for example, typically shed their acorns just before most leaves drop. Their acorns benefit from the cover of newly fallen leaves, which ensures that some acorns will be hidden from predators, while others will be found and dispersed by squirrels and chipmunks intent on hiding their winter stores.
Banner crops of acorns come every three or four years. One researcher tracked 15,000 acorns that were dropped by one prolific tree. Deer, squirrels and other animals ate 83 percent of them; six percent were attacked by weevils and insect larvae and about 10 percent were naturally imperfect and failed to germinate. Less than one percent actually sprouted, and more than half of those died as seedlings. Fortunately, only one acorn needs to survive to replace the adult tree above it.
Whatever the strategy employed, it’s clear that NASA couldn’t have designed better spaceships than the seeds of most plants.
TURKEY VULTURES SOARING
Autumn raptor migration begins in late August and continues until the snow flies, but one of the more remarkable raptor migrations to observe occurs over the bluffs surrounding Devil’s Lake State Park. We’re not talking about just any raptor, but the turkey vulture. To see up to 300 turkey vultures elegantly soaring on the thermals in early October—the sky over Devil’s Lake seemingly filled with them—can be thrilling!
While turkey vultures may have a face that only a mother can love, no bird may be more masterful at effortless migration. They can soar for hours, rarely flapping their wings, but often shifting the direction of their flight with subtle twists of a wing. When they want to head south, they soar up and up, then set their wings and drift, gaining 14 feet for every foot they drop, a glide ratio only eclipsed by ocean-traveling albatrosses. Seen from the side, they hold their 6-foot wingspan in a shallow V when soaring. Seen from below, vultures appear two-toned, black wing linings against gray flight feathers, with silver primary feathers along the trailing edges of their wings.
Devil’s Lake is one of the largest staging areas in the Midwest for turkey vultures, where more than 25 percent of Wisconsin’s population gathers before flying to Central and South America. Devil’s Lake resides within the Baraboo Hills, which contains the largest block of southern forest in Wisconsin and one of the largest in the Midwest. Designated as an Important Bird Area in Wisconsin, the southern range of the Baraboo Hills was also designated as a National Natural Landmark by the National Park Service in 1980. The Nature Conservancy has also named the Baraboo Hills a Last Great Place, one of only 200 such sites worldwide.
The best time to see the vultures is before sunset or early morning as the thermals begin to rise off the warming cliffs. Enjoy what some consider this most physically ugly of birds, yet perhaps the most beautiful of all in flight.