Sunday, March 21, 2010

Where have all the Monarchs gone?

This morning Dr. Chip Taylor was featured on ABC's Good Morning America. He talked about the steep decline in Monarch butterfly sightings across the United States. Monarchs are a harbinger of the season, yet the numbers of Monarchs seen are 1/4 of usual. Why? Torrential rains in Mexico, climate change, habitat loss all contributed. Dr. Chip Taylor interview

While the record low numbers of Monarch butterflies returning from Mexico are startling, the news from California is grim, too.  Every year the Xerces Society conducts counts at the various overwintering sites during the week of Thanksgiving. The 2009 year numbers are not posted yet, but it is known that numbers are 30 to 40% lower than last year - and last year had the third lowest number of Monarch butterflies ever recorded at the California overwintering sites. Here is a graph I compiled of earlier numbers:
 (You can read about our November trip visiting the California Monarch overwintering sites California Monarch Overwintering Site Trip Blog)

It is well accepted among scientists that Monarch butterflies East of the Rocky Mountains migrate to the mountains near Mexico City for the winter. Those West of the Rockies overwinter along the Pacific coast of California. Chris Kline began the Southwest Monarch Study in 2003 to learn where Monarch butterflies in Arizona go, south of the Rockies - or if they go anywhere at all. While his study is still continuing, he has some interesting results thanks to many citizen-scientists monitoring Monarch populations around the state. Monarchs tagged in Arizona have been recovered in both Mexico and California, and a few stay for the winter.

 What about here in the Phoenix metropolitan area?  For the last four years a small number of Monarch butterflies overwintered at the Rio Salado Restoration Habitat and the Desert Botanical Garden. In the Fall it looked like this year's population would be higher than last year's, then fierce storms with high winds struck the Phoenix area decimating their numbers. In January, I only spotted one lone Monarch at the Rio Salado overwintering site. By early February the Desert Botanical Garden's population was reduced to five male Monarchs, who left the area shortly after mid-February likely searching for mates. 

I looked at my records from last year of Monarch sightings locally as a comparison. By mid-March most of the Monarchs left Rio Salado, likely due to lack of milkweed. (This year volunteers planted milkweed as a life-line host plant for female Monarchs to lay their eggs.) But the activity in March 2009 at the Desert Botanical Garden began to accelerate with mating and egg-laying on milkweed around the garden. By March 4th I noticed four Monarch caterpillars near the Butterfly Pavilion and by March 9th there were another seven. 

Within a few weeks the air erupted in fluttering orange wings dancing through the lavender and other nectar sources in the garden. April witnessed another mating frenzy and the last Monarch left the area in mid-May when temperatures began to rise over 100. Compare these numbers to 2010 when I only saw one lone female laying eggs on Tropical Milkweed last Monday, March 15. We are watching the three eggs she laid closely to see if they become caterpillars.

What are we doing in the Phoenix area to save the Monarch Butterfly?
  • Last weekend we worked with the Hassayampa Preserve, part of the Nature Conservancy, to learn about the Monarch Butterfly in Arizona and plant milkweed: Asclepias subulata, Asclepias linaria and Asclepias subverticilatta on the preserve.
  • Planted Desert Milkweed, Asclepias subulata, at the Rio Salado Restoration Habitat and are planning to have a workday to plant Narrowleaf Milkweed, Asclepias angustifolia, in the near future.
  • Planted milkweed seeds at the new Audubon Center along the Salt River.
  • Offered workshops on Monarch Butterflies and planting milkweed at the Veterans Oasis Environmental Center in Chandler.
  • Worked with the Desert Botanical Garden to encourage everyone to buy milkweed to provide rest stops for monarch in their home landscaping.
  • Offered workshops advocating Monarch Butterfly conservation and awareness at local and distant Audubon chapter meetings.

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