Wednesday, October 9, 2013

Grand Canyon Monarch Butterfly Population

Monarch nectaring on sunflowers at the Grand Canyon
Our favorite vacation destination is the ever changing Grand Canyon National Park in northern Arizona. While the etching of this great geological wonder is slow, for over thirty years our family has uncovered new discoveries each time we visit about it's many natural splendors.  When we were young, we hiked the trails absorbing the ages of time around us. Once, to make our travels light, we rode the mules. We learned quickly that for us hiking was much easier. We’ve rafted the mighty Colorado River several times between the steep Canyon walls and over treacherous rapids. We have fallen asleep to the roar of monsoon storms pummeling the deep gorges with thunder echoing and rebounding off the walls. More recently we enjoyed a cabin on the South Rim savoring the Canyon’s many moods – and watching monarch butterflies shoot up out of the Canyon each afternoon like bullets from the river far below.

Monarch nectaring on New Mexico Vervain
The number of monarch butterflies we see at the Canyon fluctuates. Last year they were abundant, the most we’ve ever seen. This summer the monarch population was more typical, but still exciting to watch. Like earlier visits we witnessed egg-laying and larvae, pristine and shredded winged monarchs, and enjoyed watching adults nectaring. But monarchs often reveal new survival strategies when the circumstance is right and it’s fun to look for them. This year we found monarchs nectaring on New Mexico Vervain, Verbena macdougalii, in damp meadows. Of course they still favored Horsetail Milkweed, Aslcepias subverticillata, Rabbitbrush, Chrysothamnus spp., and Sunflowers, Helianthus spp., as well.

Monarch nectaring on Rabbitbrush
The Grand Canyon is home to three varieties of Rabbitbrush and each has its own bloom period. As one is senescing, another is just coming into flower. As a result it is a major and continuous late summer and Fall nectar source. Monarchs chase the rabbitbrush bloom around the Canyon then stay in nearby trees for shelter, a perfect bed and breakfast.  We found monarchs roosting in pine and junipers alike, usually on the South and Southeast portions of trees. You could often find them shortly after sunrise sunning with open wings to warm before dipping down to feed.

Monarch on Horsetail Milkweed, Asclepias subverticillata
Like previous years, monarch numbers were densest at the edge of the canyon closest to the Bright Angel Cabins. We stood by the rim on warm afternoons and watched monarchs fly up out of the canyon, then appear to hover a moment, and gracefully glide over treetops to nearby milkweed and nectar just to the South. From sightings along the South Bright Angel Trail it appears they follow the creek and nectar up through Indian Gardens then follow the canon gorge up.

Joe, an Interpretive Ranger at the Grand Canyon
But there was something very different about the Grand Canyon this year - the National Park Service employees chasing monarchs. Joe joined us tagging last year and was the first to create a Ranger monarch logging system for our data to record sightings by the public. There is something very special about spotting a ranger with a net on his back riding around the Canyon looking for monarchs!

Marna, Grand Canyon Park Guide
Marna, a Park Guide for the National Park Service, was inspired by her encounter of monarchs last year to create this beautiful detailed monarch painting that hangs above her desk.

Monarch larva
This year we were invited by the National Park Service to share monarch presentations at the Grand Canyon school for the K, 6, 7, 8 and 10th grade classes. Afterwards, each grade walked around the school grounds to identify monarch host and nectar plants. The sixth grade class was the first to find a monarch larva on Horsetail Milkweed, Asclepias subverticillata! Classes decided on seeds to collect and grow in their greenhouse this winter. We'll return next Spring to help with their Earth Day butterfly garden installation for their phenology project. 

In the evening we shared a public presentation on Monarch Butterflies at the Grand Canyon at the Shrine of the Ages. We were excited by the international interest in the monarch migration phenomena. For us it was a wonderful experience to be able to share new understanding about the monarch butterfly migration through Arizona at a place that has touched the heart of our family so deeply for a lifetime. 

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