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Index of Subjects At 3:58 PM +0000 7/5/15, Stephen Shaw wrote: >The Xerces outfit (see url below from Peter) has quite a wide mandate. The founder of the Xerces Society, Bob Pyle, was (and still is) a hero of mine. His book, the Audubon Society Handbook for Butterfly Watchers, was a godsend for me in the mid-80s and should be required reading for any/all butterfly watchers... >I'd heard about one species (Anax junius), but was surprised to >learn from the Xerces site that they know or suspect that at least 5 >species of dragonfly are north-south migratory, like some >populations of the monarch butterfly. Most of the monarch >populations world-wide are non-migratory, and surprisingly, >molecular phylogeny reveals that the migratory habit of the North >American groups apparently developed as a later offshoot in >evolution, not early. I don't find it particularly surprising that many dragonflies are migratory, only that it took us so long to figure it out (!). For more info about dragonfly migration, I urge folks to visit the Migratory Dragonfly Partnership site at http://www.migratorydragonflypartnership.org/index/welcome The migratory habit (I use "migration" loosely when in comes to Monarchs since they are only one-way migrants) in North American Monarchs is likely due to a single factor, the natural north temperate (seasonal and continental) range of Asclepias syriaca, the "common" milkweed. I think that Monarchs are best considered "re-colonists" in their spring northward movements since they follow the seasonal emergence of milkweed and "leap-frog" over preceding generations. The Danaids, as a whole, are almost entirely restricted to the tropics except for two species, D. plexippus (the Monarch) and D. gilippus (the Queen), however, the Queen is a far more recent arrival, dependent on the rapid incorporation of A. curasavicca (the tropical milkweed) into gardens across much of North America. The Queen is now known to "migrate" as far north as New Jersey in some years. There are many other migrants in the Danaidae, including the Blue Crow (Euploea core), which congregate seasonally in roost sites due to seasonal changes in moisture regimes (eg. dry and wet seasons), all WITHIN the tropics. Phil -- Phil Schappert, PhD 27 Clovis Ave. Halifax, NS, B3P 1J3 philschappert.ca imaginaturestudio.ca imaginaturestudio.blogspot.ca philschappert.com "Just let imagination lead, reality will follow through..." (Michael Hedges)
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