The striking displays of annual animal migrations are eagerly observed by many, from hawk watchers perched on towers to Monarch watchers gazing into the skies and whale watchers shivering in boats. Migration as a behavioral phenomenon is difficult to measure and interpret, and as we stand on the threshold of new discoveries about dragonfly migration, the question arises as to whether we can glean some insights from other animal migrants whose migration routes and behaviors have already been pieced together. As Hugh Dingle, the author of Migration: The Biology of Life on the Move opines, "A full understanding of migration and its implications requires knowledge of diverse [organisms] and contributions from several biological disciplines."

 

What can we learn from other migrants? Many observers spotted the iconic Monarch butterfly in directional flights together with migratory dragonfly species this fall. A Hawk Watch observer spotted upwards of 10,000 dragonflies joined by migrating Monarchs as they flew past a tower in eastern Toronto. A few weeks later, Monarchs were reported further down the coast of Lake Ontario flying in the same west-southwest direction as Common Green Darners (Anax junius) and Black Saddlebags (Tramea lacerata), both groups presumably orienting their flight along the shoreline to skirt the open lake. In mid-October, dragonflies in astonishing numbers were reported coincident with Monarchs along Florida's coastal panhandle. Migratory species often follow geographical "leading lines" that are likely to be coincident for multiple species. If the same cues unite migratory species in space and time, we may learn important lessons from animal migrants whose routes and destinations are already revealed.

 

Migration also involves other stages and behaviors that aren't detected as easily. For example, Monarchs need milkweed "way stations", where weary adults find nectar to feed on and host plants to lay eggs. Dragonflies likely use similar "staging" areas to rest, re-fuel, and re-group. On the west coast this year both large and small directed movements of Variegated Meadowhawks (Sympetrum corruptum) were reported, as well as aggregations of dragonflies seeking respite below a blanket of fog in the early morning hours. One observer reported hundreds of meadowhawks perched in vegetation along a coastal headland, and others witnessed directed flights further south on the Oregon coast on the same day. Had these resting meadowhawks decided to move on? On the next day, dragonflies in the thousands were seen coming in off the ocean in Washington, with large numbers again reported resting in vegetation along the Oregon coast the following day, but although several observers were looking for more directed coastal flights, none were seen for the rest of the season. This makes us wonder if smaller southward movements along the coast are overlooked, particularly later in the season when weather may be increasingly unfavorable. Where are they going and why? 

 

Fleeing a harsh winter and finding new breeding sites is a common theme for migrants, but each species has its own story to tell. It's easy to forget that only about 40 years have passed since overwintering sites of northern migrant Monarchs were definitively described. Fred Urquhart and his wife and fellow scientist Norah Patterson spent decades studying Monarch migration, perfecting a wing tag in 1940 and enlisting the aid of thousands of volunteers. The seminal discovery of a Monarch overwintering site was made by a pair of citizen scientists who after searching in vain for two years came across millions of butterflies in 1975 at 10,000 feet above sea level on the border of the states of Michoacn and Mxico. 

 

We know dragonflies migrate to take advantage of overwintering habitats in southern locales, but many details are still to be discovered. Are they overwintering in large aggregations or dispersing across the landscape? Do they pause at staging areas to assemble in mass flights or to rest and re-fuel? How many generations are involved in single migration cycle? The story of the Monarch butterfly illustrates the critical importance of volunteer monitors, not only in capturing the details of movement and life history, but also in providing a huge long-term dataset that has enabled the detection of serious population losses in a species considered to be widespread and abundant-just like our main migratory dragonfly species are today.

JOURNEY NORTH & SOUTH
Volunteers who observe Monarchs and other migratory species on their annual journey north and south may notice coincident dragonflies in flight. These sightings can help us understand the phenomenon of migration in dragonflies. If you've witnessed a dragonfly migration, submit your reports here! 

PARTNERS IN MIGRATION
Check out HMANA's website for info on collecting dragonfly migration data at HawkWatch sites in 2014.  
  
MONITORING PROTOCOLS
Make sure you have the most recently updated copy of the MDP monitoring protocols booklet to assist in your data collection efforts. 
 
  
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Photo Credit: Banner: Dragonfly migration in Xalapa, Mexico at the dunes of Canasaburro, 
by Elisa Peresbarbosa Rojas; 
Side Bar: Monarch illustration, by Peter Burke

 

Migratory Dragonfly Partnership  I  628 NE Broadway, Suite 200  I  Portland, OR 97232 USA
www.MigratoryDragonflyPartnership.org

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