8/19/11

A Northwoods Almanac for August 19 – September 1, 2011

Mergansers Families

Jane Flanigan sent me a photo of an adult red-breasted merganser with 16 young, wondering if this was a normal clutch size or merganser day care. The average clutch size is 8 to 10 for both red-breasted and common mergansers, or at least so says the books. A clutch of 16 usually means a combined family. However, "egg dumping" sometimes occurs where a female will lay her eggs in another female’s nest, and thus one female can end up with a big clutch like this.

Long Distance Journeys

By now everyone has likely heard about the “St. Croix, Wisconsin” cougar that was killed in Connecticut after walking over 1600 miles from its probable origin in the Black Hills of South Dakota. The cougar was struck by a car in Connecticut this June and was confirmed through DNA tests to be the same cougar that travelled through Minnesota and Wisconsin in 2009-2010. The 140-pound cat was hit on a highway in Milford, Connecticut, just 70 miles from New York City.

             The St. Croix cougar was first detected in Champlin, MN on December 5, 2009, about 15 miles northwest of downtown Minneapolis. It was last detected by the Wisconsin DNR near Cable, WI on February 27, 2010. The straightline movement of the St. Croix Cougar from its initial detection in Champlin to Milford is 1,055 miles, but if it had traveled through the UP and through southern Ontario, the shortest distance would have been about 1,150 miles. And since the St. Croix cougar was already nearly 500 miles from the Black Hills of South Dakota, his most likely origin, his actual straight-line move was likely well in excess of 1,600 miles. This movement of a large carnivore sets the record for straightline distance – the previous record for a dispersing male cougar was 663 miles from the Black Hills to Oklahoma.

            This is an amazing story for a mammal, but some fish might not be terribly impressed. Consider lake sturgeon. In November of 1994, a five-foot-long lake sturgeon was caught in a commercial fisherman's net in Saginaw Bay, MI, and was traced by its aluminum tag to have begun its journey from Lake Winnebago, 450 miles away where it had been tagged in October of 1978 by the WDNR. What makes this journey particularly remarkable is that the sturgeon had navigated the lower Fox River, which has 14 dams and 17 locks on it, before reaching Green Bay, and then wandered through Lake Michigan, the Straits of Mackinac, into Lake Huron, and finally down the east coast of the Lower Peninsula to Saginaw Bay. In those sixteen years, it had grown 8 inches, an average rate of growth for sturgeon.

That’s remarkable indeed, but another sturgeon was taken in Lake Erie five years after it had been tagged in Lake Winnebago, a distance of 850 miles away.

Much further afield, humpback whales travel 10,000 miles in their annual journeying, feeding during the summer near polar oceans and migrating to warm tropical oceans for the winter, making the cetaceans the farthest-migrating mammal on Earth. The distance is made all the more impressive given that the huge mammals follow nearly straight paths for weeks at a time despite surface currents, storms and other disturbances. A seven-year satellite transmitter study showed that the humpbacks never deviated more than about 5 degrees from their migratory courses, and in about half the segments mapped by the researchers, humpbacks deviated by one degree or less. The researchers concluded that the whales are orienting with something outside of themselves, not something internal. But Earth’s magnetism varies too widely to explain the whales’ arrow-straight patterns, and solar navigation requires frames of reference that water doesn’t often provide given that the open ocean is an endless horizon of blue. The researchers believe humpbacks rely on both magnetic fields and the sun, and perhaps the position of the moon and stars.

             What about birds? Well, there’s the great snipe, a relative of the Wilson’s snipe, a commoner in our area. The great snipe is a small, stocky shorebird that takes the fastest long-distance, nonstop flights of any animal not in an airplane. During its annual migration, a single snipe may fly for 96 consecutive hours, covering more than 4,000 miles. That’s four days without stopping or sleeping, sometimes at average speeds of 50 miles per hour.

While the longest known nonstop flight was made by a godwit that flew 7,145 miles from Alaska to New Zealand in nine days, its average speed was “only” 35 miles per hour compared to the great snipes’ which topped out at 50 miles per hour. Making the great snipes’ speed even more impressive was that it was done without wind assistance. When the researchers cross-referenced the flight records with wind records from U.S. satellites, they found little evidence of tail winds. Add in the fact that this was accomplished despite their rather rotund body and the relatively non-aerodynamic shape of their wings. Instead, the snipes seem to rely on massive stores of fat accumulated during autumn binge eating.

Lastly, there’s the sooty shearwater, which travels almost the entire stretch of the globe. Recent tagging experiments have shown that birds breeding in New Zealand often travel 40,000 miles (that’s not a misprint) in a year, reaching Japan, Alaska and California, and averaging more than 300 miles per day.

So, a cougar travelling 1,600 miles to Connecticut? It’s certainly a big deal, but a few other animals might see it as just pedestrian.

Mystery on the Cisco Chain

I need help figuring out this mystery. Mary Congdon, who lives on the Cisco chain in the U.P., wrote: “After a hard, sudden electrical storm (which clears quickly), the cisco are found floating on their sides on the water surface with their gills fluttering. They can then be scooped up in a net. If, however, one accidently bumps them with the net and misses, they immediately awaken’ and go to the bottom. If they are left there for a while, they will also go back down. We have lake trout at those same deep depths which do not react in this manner. I have always been curious, but never could get an answer, as to why this happens.”

Do any of you have some insight?

Migration Has Begun

            Mary and I spotted several greater yellowlegs on Powell Marsh on August 12 along with a flock of smaller shorebirds that were too distant to identify. So, shorebird migration has begun, and though our area is generally not known as a hotspot for shorebird stopover habitat, small numbers do appear along the shorelines of many of our lakes, river, and wetlands.

Migrants are not only coming through from the north, but many nesting birds in our area have already begun their exodus south. The black terns, bobolinks, and tree swallows that nest at Powell were all gone. These three species usually depart our area by mid-August at the latest, as do many of the neotropical warblers. Really, any bird species that relies exclusively on a diet of insects is getting ready for migration or has already left, because the first fall frost can occur anytime now.

            Keep an eye out for common nighthawks moving south – a birder in Wausau reported seeing a flock of 50 moving south on 8/14. The last two weeks of August are traditionally our most active migration periods for nighthawks.

Jewelweed in Flower

            Jewelweed is flowering in the moist soils separating wetlands from uplands. Hummingbirds work the tubular flowers during the day; at dusk, hummingbird moths take over the nectar patrol. Both types of hummers pollinate the flowers by picking up grains of pollen from the top front of one flower and depositing them on the next.

            The “jewel” part of the name is most apt, because of the spurred flower shape and orange color. Some folks see the dangling flowers as jeweled earrings, while others see jewelry in how the edges of the leaves sparkle with drops of water after a rain.

            The fruit pods give it another set of names, from “touch-me-not” to “poppers.” The pods pop open when touched, the outer covering uncoiling like a spring and shooting the seeds 4 to 5 feet through the air.

            For anyone suffering from poison ivy, boil the leaves, stem, and flowers of jewelweed in water until the water turns deep orange. Or crush the stem and just apply the fluid. Many people swear by the decoction as a cure for the evil ivy.

Lake Superior Swimming

            Mary and I led five consecutive days of hikes for Nicolet College last week, and on one of the days, the temperature reached 88°. We were hiking in the Porcupine Mountains State Park, so when we reached the trail’s end, we thought we’d cool off in Lake Superior, a dicey proposition given the usual frigidness of the world’s largest lake. If you don’t know the statistics, Lake Superior contains almost 3,000 cubic miles of water, an amount that could fill all the other Great Lakes plus three additional Lake Eries. With an average depth approaching 500 feet, Superior also is the coldest and deepest (1,332 feet) of the Great Lakes. The lake stretches approximately 350 miles from west to east, and 160 miles north to south, with a shoreline almost 2,800 miles long.

All those numbers usually add up to a very cold swim.

Well, remarkably, the water was perfectly comfortable, and we had as delightful a swim as one could ever want in the clear waters of Superior. The surface water temperature was around 68°, though it was a certainly nippier as one got a little deeper.

So, it’s a good time to paddle or swim along the shores of Lake Superior! For an array of data on Lake Superior, go to www.coastwatch.msu.edu/twosuperiors.html

Celestial Events

            On 8/25, look before dawn for Mars about 3° north of the waning crescent moon. The new moon occurs on 8/28. On 8/31, look for Saturn about 7° north of the waxing crescent moon.

            I’m sure you’ve noticed how late the sun is now rising and how early it’s setting, but if not, we’re down to less than 13 ½ hours of daylight as of 8/28 – autumn is on its way.