Monarchs in a mess
July 9, 2014 —
One thing I do around this time of year is check for monarch butterflies, usually by just walking down some nearby roads; there are a few milkweed plants growing off the side of the roads that will support caterpillars. I check some of the plants for the tiny white eggs that will eventually result in a new generation of monarch butterflies late in the summer. This year, however, my hunt has been in vain. Glimpses of orange flittering in the distance usually turn out to be fritillary butterflies, and what looked like a sighting during a recent bird walk by a friend turned out to be a viceroy butterfly; it has orange wing patterns that closely mimic the monarch.
Last fall, counts of migrating monarchs were way down at many sites where hawk migration counts are conducted, as stated in my Sept 18 column of last year www.riverreporter.com/column/river-talk/7/2013/09/18/tale-two-migrants. This year the situation looks even more dire for the monarch. The Mexican government and the WWF stated in a recent news conference that the wintering grounds that monarchs use is down to 1.65 acres (a little larger than a football field). This is about half of what the wintering ground was the previous year. By expert accounts, what was once a migration of a billion or more individuals is now down to about 35 million from the Mexican wintering grounds.
Not all the blame can go to habitat loss in Mexico. In the Great Plains, where the bulk of the migration takes place, modern agricultural practices are taking their toll. Because of higher corn prices, driven by the mandated use of ethanol in fuel, farmers are planting corn where buffers once stood. Milkweed, essential for the monarch’s survival, thrived in these buffers. The use of genetically modified crops allows the crop to resist herbicide; this eliminates milkweed that previously grew between crop rows. Dr. Chip Taylor, a biologist at the University of Kansas who has been studying the monarch migration for decades, stated that when the monarchs have to use more energy to find milkweed to lay eggs, fewer eggs are laid by the females, and many will die before they get the chance to reproduce.