River Bend

To River Bend Nature Center with Dan Tallman. Our destination at River Bend is a large, flood plain pond toward the north end of the nature center. This pond, which I've visited other years, supports a source population of Horned Clubtails, one of seven stillwater gomphids of the genus Arigomphus in North America and the only one with a distinctly Northern Great Plains distribution. A. D. Whedon published the first account of this species in Minnesota, describing its emergence at a stagnant pond in 1913 near the Minnesota River in Mankato, approximately fifty miles from the pond at River Bend. Almost always the first clubtail to emerge or be observed in Rice County, I look forward to its arrival each year.

These are large dragonflies and its likely that the nymphs require several years to reach full size, though admittedly very little is known about them. Emergence takes place at the water's edge or on suitable floating platforms near shore; this species seems particularly adept at emerging from the surface of floating algae mats. The adult females sport a tall, bi-lobed, bright-yellow occipital plate that distinguishes it from other clubtails, while the horns for which it is named are much more difficult to observe, especially in the field. The male looks quite different, being more black than yellow and with a thinner abdomen, and is a fleet and furtive creature, very difficult to observe.

One of the great pleasures of being in the field with Dan is his ear for birds; he hears all the instruments in the symphony. On the hike to the pond and back, Dan singles out the song of a Red-eyed Vireo, its tireless call and response, a Redstart, a Yellow Warbler, the trill of a Tree Sparrow, and the defiant tree-top blast of an Great Crested Flycatcher. When I ask what the mnemonic for the rather harsh call of the flycatcher might be, he smiles and answers, "Squawk!"

Approaching the pond we find the year's first Horned Clubtail. I suspected we'd see many more at the pond, but we only saw one more and that one from afar as it emerged on a float of algae some distance from shore. Probably there were others but their presence was simply masked by the mass emergence of Dot-tailed Whitefaces. Every step we took around the entire circumference of the pond flushed into flight dozens of newly emerged dragonflies. Several male Twelve-spotted Skimmers performed their showy (if not pugnacious) flight displays over the water, battling with each passing Common Green Darner. A Belted Kingfisher persisted in doing head-first dives into the shallow water, somehow avoiding serious neck injury or becoming stuck in the bottom. From a distant the pond appeared to be covered by a white haze, but this haze dissipated into thousands of white flowers of the Water Crowfoot.

Posted on 27 de maio de 2017, 03:14 AM by scottking