A Northwoods Almanac for October 8 – 21, 2010
Loon Migration and Avian Botulism E
I recently attended portions of a two-day meeting organized by the University of Wisconsin Limnology Center entitled “Science in the Northwoods.” Over 60 presentations were given on current scientific research taking place in our area with each researcher given five minutes to summarize his/her research.
In this column, however, I want to share just one of the presentations, because it refers to events taking place right now with loons. Kevin Keenow, a biologist with the U.S. Geological Survey and the Upper Midwest Environmental Sciences Center in La Crosse, WI, discussed the movements of migrating loons and their foraging patterns in northern Wisconsin, with a particular focus on Avian botulism E, a neuromuscular illness caused by a toxic bacteria (Clostridium botulinum). In birds, botulism E produces weakness, dizziness, inability to fly, muscular paralysis, and respiratory impairment, and is often fatal among fish-eating birds like loons and gulls in coastal and Great Lakes ecosystems. The bacteria typically live in lakes and wetlands, but only sporadically produce the toxin when certain environmental conditions apparently develop. Recent history in Wisconsin includes small Botulism E die-offs in 2006, 2007, and 2008 in the Door County area of Lake Michigan, and much larger die-offs along the Lake Michigan shoreline in western Michigan and in Lake Erie.
While Botulism E has been implicated in waterbird deaths in the Great Lakes since the 1960’s, in the last decade these mortality events have increased dramatically. Keenow noted that since 1999, 49,467 waterbirds have been recovered that died from Botulism E, of which over 24,000 were common loons. Unfortunately, this only represents the carcasses that were found. Researchers estimate the total mortality at over 80,000 waterbirds in the last decade.
It’s not just waterfowl that are affected. Botulism E-associated mortality has also been documented in endangered or special concern species, including piping plover and lake sturgeon.
In response to these outbreaks, the WDNR began monitoring waterbird deaths in the fall of 2008 to identify botulism E outbreaks (and other diseases) along the Wisconsin shores of the Great Lakes. Throughout the later summer and fall, when most Botulism E occurs, DNR personnel are conducting active transect surveillance along the shorelines of Door County and on islands in both Green Bay and Lake Michigan. In addition, in 2009 DNR researchers began a study of the impacts of Botulism E on the Wisconsin breeding populations of common loons.
Then, in July 2010, 10 common loons were equipped with satellite transmitters to provide information on their movements over the next year. The marking of common loons this summer was part of an effort to study the migratory movements and foraging patterns of loons while they migrate through the Great Lakes in association with the USGS study on avian botulism. In addition to satellite transmitter-marked loons, nearly 80 loons were equipped with a geolocator tag. These devices are programmed to record a daily location estimate, temperature, and pressure data to provide information on foraging depths.
Right now, little is known about what habitats loons use along their entire migratory routes, and it’s unclear what drives the outbreaks of botulism. In order to come up with a strategy to combat the botulism-related deaths, the researchers hope to better understand the feeding patterns of loons during migration, where along the way exposures to the botulism is occurring, and how the botulism works its way up the food chain. It appears the botulism outbreaks are related to environmental variables such as water quality and food web structure.
Movement of the loons carrying satellite transmitters from previous studies and loon movements from the current study can be followed online at the USGS UMESC website (http://www.umesc.usgs.gov/terrestrial/migratory_birds/loons/migrations.html). Of the ten outfitted with satellite transmitters, one has died, three have already migrated to Green Bay, and six are still forging on and around their breeding lakes as of 9/30.
Flooding
At our home on the Manitowish River, the river has risen to its highest flood stage, a level that we ordinarily only see at the peak of heavy snowmelt in April. So, we’ve gone from a famine of water in May to a feast in early October, a reversal of typical water flow regimes.
Of course, our flooding is only a small part of the flooding occurring around the state. I was in Baraboo on 9/27 when the Wisconsin River reached the highest flood levels ever recorded. In nearby Portage, the Wisconsin peaked at 6 feet above flood stage, and was considered a “100 year flood.” The Wisconsin reached 7 feet above flood stage in Merrill and flooded the sewage disposal plant there. At Rothschild, the river reached 4 feet above flood stage.
Later in the week I was in the New London area where the Wolf River had topped its banks. Flooding also occurred throughout Western Wisconsin in Buffalo, Crawford, Grant,
La Crosse,
Pepin, Pierce,
Trempealeau,
and Vernon
counties.
Autumn floods are quite unusual, of course, given the more typical diminishing water levels in river systems throughout the summer and fall. Flooding in the spring provides a host of positive benefits to river systems. But flooding in the fall? I suspect it’s more of a mixed bag since most organisms have not evolved behaviors over time to meet such an unlikely event.
I’ll be very interested to see what water levels are like next spring after our snow melts. Perhaps we’ll actually have the high waters in the right time frame that are so necessary for the ecological health and integrity of river systems.
Sightings
More on freshwater jellyfish: Randy Neuberg on Sumach Lake in Arbor Vitae wrote to tell me that in 2008 he observed thousands of freshwater jellyfish in the lake. He’s lived there since 2001 and had never seen anything like that. Randy noted that he spends quite a bit of time on the lake fishing and that in the area where he was seeing them the most (the south end of the lake), “There wasn't a fish anywhere nearby to be had. It is one of my most productive areas to catch fish and I didn't even get a nibble. So I highly doubt the fish were feeding on these creatures. I feel that they really didn't care to be around them.”
Fox sparrows and northern juncos are migrating through. They both arrived at our feeders on 10/2.
Witch hazel came into bloom at the end of September. As arguably our latest flowering shrub, the flowers will hold on well into November, defying heavy, killing frosts and extending the flowering year into the first snows. The fruit, flowers, and next year's leaf buds all appear on the branch simultaneously, a rarity among trees.
The name witch in witch-hazel apparently has its origins from the Old English wice, meaning "bendable". Hazel, on the other hand, is likely derived from the use of the twigs as divining rods, just as hazel twigs were used in England. Since divining for water is also called “witching” for water, this may also have influenced the origin of the name. One way or another, the yellow flowers, while not showy, are a most welcome source of color in the whitewash of early winter.
First Frost
We had a series of very light frosts in early-to-mid-September (9/5, 9/9, 9/15, and 9/19), but our first hard frost of the year didn’t occur until September 26. This follows the pattern of later fall frosts that we’ve experienced over the last decade. When Mary and I moved to our home in Manitowish in 1984, we learned very quickly to expect our first hard “fall” frost around August 20. Green tomatoes were all we ever got out of the garden, and in fact we often debated whether we should even bother to try to plant tomatoes or other hot weather plants like green peppers, eggplants, and melons because they were an inevitable failure. These days that’s no longer an issue. We seem to be able to reliably count on a 100-day growing season rather than a 70-day season.
This is a good news/bad news issue. While good for our table fare, a longer growing season grows other things besides garden crops. Winter bounds the Northwoods in every way. It’s the ultimate limiting factor for all plants and animals, and to alter its long reach may be to fundamentally alter the life processes that define the North Country.
While pondering the implications, we’ll continue to enjoy our last tomatoes picked on 9/25.
Dawn Fog
We’re now in the season where nearly every morning brings a beautiful tunnel of fog over the Manitowish River that is slowly burned away by the rising sun. The horizontal light goldens the fog and offers an ethereal beginning to many October mornings.
Celestial Events
Since the new moon occurred last night, 10/7, the dark sky will provide an excellent backdrop for the Draconid meteor shower, which peaks tonight, 10/8. The radiant point of the Draconid meteor shower occurs within the head of the constellation Draco the Dragon in the northern sky. And though the Draconids are rated at a mere 10 meteors per hour, on occasion, Draco has been known to spew forth hundreds – if not thousands – of meteors in a single hour. However, an outburst is not predicted for this year, but one never knows. Unlike most meteor showers, more Draconid meteors are likely in the evening than in the morning hours after midnight, so look northward after sunset for the very slow-moving Draconid meteors.
On 10/9, look for Venus about 3 degrees south of the two-day-old crescent moon. Also look for Mars, which will be 4 degrees north of the moon.
We’re down to 11 hours of daylight as of 10/14.
The Orionid meteor shower peaks before dawn on 10/21. The Orionids tend to be fast, occasionally leaving persistent trains and producing bright fireballs. They appear to originate from the north of Orion’s bright ruddy star Betelgeuse and are typically at their best about one to two hours before dawn. On a dark, moonless night, this shower exhibits a maximum of about 15 meteors per hour; however, this year the light of the nearly full moon will wash out all but the brightest Orionid meteors.
No comments:
Post a Comment