River Bird Blog

Copyright 2007 by Richie Swanson

Kik! cries a black tern, dangling a fish from his bill, his wings as densely dark as a massing thunderhead, edged a grayish stratus-white on front. He flies from a remote slough at Aghaming toward a marsh at Trempealeau National Wildlife Refuge, once called the species’ most important breeding area on the Upper Miss. Will he land on a muskrat house, a potential nest site? Feed a female in display? He vanishes, but a second plummets suddenly-crookedly as if after a minnow, then veers jerkily with four others, their wings knifing higher than the river-bluffs, performing early courtship flights. Black terns declined 84.8% in the U.S., 1966-1989, 4.6 % per year on the Mississippi Flyway, 1966-2003. Winter flocks have decreased precipitously, and scientists fear DDT and other contaminants accumulate in black terns south of the border, perhaps causing problems in reproduction in North America.

The black tern migrates from as far south as Peru, rarely from coastal Argentina, flying north across the U.S. in a broad front, breeding in mixes of emergent vegetation and open water from British Columbia to northern New England. Their winter fish supplies, including anchovies, have been over-harvested, and reduced in Panama by the exotic peacock bass.

Their inland marshes have been drained, choked by exotic plants like purple loosestrife, polluted by urban and agricultural run-off. Their insect-prey most likely pass on pesticide-contamination, and they also disappear from spraying. The increase of floods on big rivers like the Mississippi and Minnesota increase the inundation of the mud mounds, mud-and-algae mats, vegetation-heaps and other structures used for nests. Boat wakes may destroy chicks and eggs. Human-friendly predators include great-horned owls, ring-billed gulls, raccoons and crows.

Nearly every June, black terns defend territories at Osprey Marsh, growling krrr, jabbing bills. They fly, dip and swerve so unpredictably they almost make a river-bird watcher seasick. Yet Friday another threatened species in need of healthy-protected wetlands flew faintly white through the dark-blue dawn above Osprey Marsh, moving silently downriver with mist-clouds that floated south and shrouded bluffs barely gray-green. One great egret&two&five&160 in all flew from a nearby breeding colony until a sun-glow lit the smoky mist, outlining the bluffs, tingeing crane-like necks, bellies and undersides of wings yellow.

Wisconsin lists the egret as legally threatened, for it nests high in tall trees in large blocks of floodplain forest, more than 90% gone in the state. Plume-hunters extirpated the species from most of the U.S. by the early 20th century, shooting birds at nest colonies. The Migratory Bird Treaty Act stopped the killing in 1913. Great egrets bred again in Wisconsin in 1939; in Minnesota, not until 1980.

This morning, an egret fluffs and spreads its aigrettes, tail-plumes, in emerging bulrush, then scratches a snowy cheek elegantly with black claws. It blinks with lime-green eye-rings, hunches nearly horizontally, flaps and lunges, stabs water, wiggles and shakes its throat, perhaps gorging on green or northern leopard frogs. It hunts for hours as if feeding nestlings.

Muted grunts groan low. A hooded merganser swims through the bulrush, the flare of her reddish-brown crest translucent with sun. She slips across a log, and ten chicks converge behind her. An eleventh jumps against the log, bounces backward, jumps three more times, finally joins the others splashing, dipping heads beneath water, feeding probably on aquatic insects. Canada geese have goslings; mallards, ducklings. Though no wood duck young appear, some drakes already loaf in eclipse on logs.

A prothonotary warbler chips from a moss-covered deadfall. She grabs and pulls. Her bluish wings flap backward. She raises her yellow face 14 times, a green mass hiding more of her after each peck. She flies and descends into the top of a nest-stump.

Last years milkweed stalk quivers above a shore dense with switch grass. A Baltimore oriole flaps up, dangles upside down and digs her bill into the stem, stripping it until her bill fills with curly-stringy fibers. She whistles a single piping note through the plant-hairs, rattles a chuck. Though her mates brilliantly orange, and shes bright for her sex, the two disappear easily in overhanging maple foliage. Then she pulls a hair from a grapevine with fresh-red stems, building a basket-nest somewhere.

A great-crested flycatcher wit-wit-weers, whee-ups, rurrs through a mouthful of dead leaves. Her gray head and throat blend with the maple snap-off she perches atop. Her yellow breast blurs with sun-mottled foliage. Her rufous tail reddens like bark. She drops inside the snap-off, emerges, cocks her head as gently as a dove. A male rasps, and the two zoom through treetops, leaving a nest-cavity in a dead branch nearly four-feet deep. The species have filled such deep holes with snake skins, wrinkled plastic, horsehair, birds wings, squirrels tails, manure, all kinds of paper and trash.

Great-cresteds sometimes rely on abandoned woodpecker holes, using excavations of red-headed woodpeckers, but populations of the latter species have declined by half since 1966. Causes probably include losses of grasshoppers and other insect prey, collisions with automobiles, creosote in telephone-pole nests, clearing of dead snags, and loss of open forests and forest-edges to logging, agriculture and other developments.

Red-headed woodpeckers usually arrive in southern Wisconsin by late May, but none have quirred, queeked or flashed scarlet-and-white around bare-dead trunks here yet. I still have not encountered the species at Aghaming since 1998.
SOURCES

Agro, D.J., and Dunn, E.H. 1995. Black Tern (Chlidonia niger). In the Birds of North America, No. 147 (A. Poole and F. Gill, eds). The Birds of North America, Inc. Philadelphia Pa.

http://audubon2.org/webapp/watchlist/viewSpecies.jsp?id+176

http://dnr.wi.gov/org/land/er/factsheets/birds/Gregret.htm

Faber, R.A. 1992. The Black Tern: Effect of Water Level Fluctuations on Hatching Success and a Census of Nesting on Pools 5 and 7. FWS Grant Agreement No. 14-16-0003-91-984. Winona Mn.

Lanyon, W.E. 1997. Great Crested Flycatcher (Myiarchus crinitius). In Birds of North America, No. 300 (A. Poole and F. Gill, eds.) The Academy of Sciences, Philadelphia, Pa, and The American Ornithologists’ Union, Washington D.C.

McCrimmon, D.A., Jr., J.C. Ogden, and G.T. Bancroft. 2001. Great Egret (Ardea alba). In The Birds of North America, No. 570 (A. Poole and F. Gill, eds.). The Birds of North America Inc., Philadelphia, Pa.

Novak, P.G., J. Soule, and R. Jennings; revisions by G. Hammerson and D.W. Mehlman. 1998. Nature Conservancy Species Management Abstract. Black Tern (Chlidonia niger). The Nature Conservancy, Arlington Va.

Robbins, S.D. Jr. 1991. Wisconsin Birdlife. The University of Wisconsin Press. Madison Wi.