NWA 8/9/13

A Northwoods Almanac for 8/9 - 22, 2013  

Enormous Decline of Monarchs

Many people have commented to me this summer that they’re not seeing monarch butterflies at all. At first, I thought it might be due to our inordinately delayed spring, but there’s a much bigger story going on. Last winter, scientists surveying monarch habitat in Mexico's Monarch Butterfly Biosphere Reserve found the insects occupied 59 percent less land than the previous year—the smallest area ever recorded. Nine butterfly colonies were found in just 2.94 acres of land, compared with 7.14 acres in 2011 and a high of 44.9 acres in 1997.

It's normal for the monarch population to vary from year to year – a storm in January 2002 killed 80 percent of those overwintering in Mexico, but the population was near normal a little more than a year later. However, this year's steep decline is being blamed on two main causes: extreme climate fluctuations, including long-term drought, plus heavy spring rains and cold this year, and widespread loss of milkweed, which the monarch caterpillars rely almost entirely on for food.

The monarch doesn't fare well in extreme weather, and last summer's Midwest drought was the worst in 25 years. March 2012 was the warmest recorded since nationwide record keeping began in 1895. The first generation monarchs moving north-northeast out of Texas arrived much earlier in the northern breeding areas than previously recorded. These early establishments were followed by one of the hottest and driest summers in recent decades. Hot and dry conditions are believed to have the effect of reducing adult lifespan, and therefore the number of eggs laid per female over their lifetime. Plus temperatures above 95˚F can be lethal for larvae. Six of the last seven years have shown drops in monarch populations, and there are now only one-fifteenth as many monarch butterflies as there were in 1997.

It’s not just about conditions too hot and too dry. Monarch eggs, larvae, and pupae develop more quickly in milder conditions, thus the long cold and wet spring this year also meant that monarchs have been slower to reproduce and migrate.

Another factor in the decline is the use of pesticides to treat weeds in the American Midwest. The Midwest is a key habitat for monarchs because of milkweed, which thrives along the borders of its corn and soy fields. When farms began to use the herbicide Roundup on genetically modified corn and soy in the early 2000s, milkweed disappeared, and with it, the monarchs that use it to feed and reproduce. The herbicide-resistant crops can withstand the chemical spraying, but the milkweed can’t.

The push for the production of biofuels has contributed to the loss of milkweed, too. Over 25 million more acres of corn and soybeans have been planted since 2006 at the expense of Conservation Reserve Program lands which supported high numbers of milkweed plants. The recent high prices for corn have also created more intensive farming, which has reduced the area from the edge of roads to the farm fields. Towns and counties also are now increasingly using herbicides for management of roadside weeds, which also eliminates milkweeds.

Logging was once considered the main threat to the winter reserve area, located west of Mexico City. At its peak in 2005, logging devastated as many as 1,140 acres annually in the oyamel fir forests reserve, which covers 193,000 acres. But a 2012 aerial survey showed almost no detectable logging, the first time that logging had not been found in detectable amounts since the mountaintop forests were declared a nature reserve in 2000.

The problems associated with extreme weather and genetically modified crops are far larger than crashing monarch populations. Vera Krischik, a University of Minnesota entomology professor, believes that honeybees, bumblebees, parasitic wasps and many other kinds of beneficial, pollinating insects — including other butterflies — are also noticeably absent this year.

A Hundred Billion Planets in the Milky Way

            Mary and I led several hikes for Nicolet College last week, and one of the participants on the hikes was Dan Schroeder, a retired astronomer who worked on the building of the Hubble telescope. Dan and his wife LaVerne have hiked with us many times over the years, and we always try to ask Dan what the latest news is in the world of astronomy. And this time, the word was “Planets,” and lots of them.

            Dan recalled back in 1996 when an announcement was made that two planets had been discovered orbiting a sunlike star. The observation shook the world of astronomy, because no one had been looking for planets under the assumption that they would be too hard to find. Now, astronomers had reason to look, and they launched an effort to search for “atmospheric biosignatures” that would provide further evidence of extrasolar planets.

Some planets were additionally discovered in the intervening years, but it took the launching of the Kepler space telescope on March 2009 to change everything. With the mission to discover Earth-like planets in our galaxy, the Kepler was designed to continually monitor stars in just one small fixed area of the sky to see if it could detect periodic dimming caused by planets crossing in front of their host star. Kepler's field of view covers around 0.28 percent of the sky, or "about two scoops of the Big Dipper." Thus, it would require around 400 Kepler-like telescopes to cover the whole sky.

In the last three years, NASA’s Kepler telescope has found enough evidence of planets that astronomers at the Harvard-Smithsonian Center for Astrophysics estimate that “at least 17 billion” Earth-sized planets reside in the Milky Way Galaxy. And they now believe that on average, every star should have at least one planet. Given that our galaxy alone has at least 100 billion stars, it must also have at least 100 billion planets that are orbiting the stars.

            The BIG question, of course, is whether any of those planets can sustain life. In March 2011, astronomers at NASA reported that about "1.4 to 2.7 percent" of all sunlike stars are expected to have earthlike planets "within the habitable zones of their stars." However, there is no specific data that currently enables astronomers to answer the question of life on other planets. Nevertheless, since there are more than 100 billion galaxies in our observable universe, and small planets have been discovered to be extremely common, odds are that other life must exist somewhere out there. See the August 2013 issue of “Sky and Telescope” for a detailed article on the latest research.

Sightings – Spruce Grouse, Greater Yellowlegs, and Albino Squirrels

From Jim Cheshire in McNaughton: “While returning from work on July 13th at about 7:45 pm, I could see a small, gray animal several hundred yards ahead in the middle to the road. As I got closer, I assumed it was a ruffed grouse dusting itself in the road. However, when I got within about 50 yards, I realized this was a different type of bird (a rare spruce grouse). So, I pulled my car over and began walking toward the bird with a camera. Near the shoulder of the gravel road I noticed about 6 tiny chicks that I hadn’t seen yet. Since they were only slightly bigger than a computer mouse, I assumed the chicks could not fly. So, I tried to line them up in the foreground with the hen spruce grouse in the background. However, the chicks quickly flew into the swamp before I could take a picture. I later learned on the internet they can fly within 6 to 8 days of hatching (which must be a great defense mechanism). The hen spruce grouse allowed me to walk to within about 25 feet before getting up and nervously walking away. I got a pretty good photograph of her in the road and another when she flew up into a nearby pine tree. I then quickly left so that the hen could reunite with her chicks.

             “Much of what the Wisconsin DNR describes as suitable spruce grouse habitat perfectly matches much of the land in this area. There are thousands of acres of black spruce, tamarack, and jack pine that spruce grouse are known to prefer. So, since there was obviously a breeding pair, I suspect there is a self-sustaining population in the area.”

            On a different note, bird migration has already begun. Warblers are starting to move south, and shorebirds have been coming through Wisconsin since late July. Mary and I observed a flock of a dozen greater yellowlegs, a shorebird that breeds in muskeg habitats of central Canada and southern Alaska, on Powell Marsh on 8/5. Yellowlegs winter in numerous countries in South America – adult birds often reach Argentina by late August.

            Nancy Eckman in Minocqua sent me photos of two albino gray squirrels that frequent her feeders.

Celestial Events

            The Perseid meteor shower peaks during pre-dawn hours on 8/12. The Perseids are rated at an average of 60 meteors per hour, or one per minute, but at their heaviest, about 90 meteors an hour are predicted.

Light conditions should be good given that the Moon reaches its new phase on 8/6, and thus will be a waxing crescent around the anticipated peak for the Perseid meteors.

The source of the Perseids is comet Swift-Tuttle, discovered in 1862 by astronomers Lewis Swift and Horace Tuttle. Swift-Tuttle is on a 133.3-year orbit, and last passed through the inner solar system in late 1992.

The Perseid meteors are not a one-night show. For several days before and after the Aug. 12 peak, you can likely catch the shooting stars.

Besides looking for meteors, don’t forget to search for planets. Look for Venus and Saturn in the west-southwestern sky at dusk. Of the two planets, Venus is brighter at negative 3.9 magnitude. On 8/9, a very skinny crescent moon cruises the sky with Venus, while on the evening of 8/12, the moon will be to Saturn’s lower right. The next night, the moon will be to Saturn’s lower left.

Look for the full moon on 8/20.