16 August 2010

Avifauna Diversity at Missouri Bottoms Inundated by High-Water

Habitat situations created by greater than normal water levels are providing a ongoing haven for many types of birds along the Missouri River in east-central Nebraska during the early times of seasonal migration.

The occurrence of an impressive variety of species is notably apparent in an area near Boyer Chute National Wildlife Refuge and other sites on the river's floodplain to the south, including Nathan's Lake, and the swamplands north of, and at the Krimlofski Tract at Neale Woods. There are also flooded lowlands at N.P. Dodge Park and corn-land to its north.

Representative lowland areas with water in the vicinity of the former Horseshoe Lake.

Lowland Waters

The prevalence of standing water is the result of two factors: increased flows in the adjacent Missouri River, and greater than normal precipitation in the vicinity.

River flows have been higher than average for several weeks prior to mid-August.

On August 12, the flow rate was 81,200 cubic feet per second, based on measurements taken at a gauge in North Omaha, according to details provided by a U.S. Geological Survey web-site. The average is 37,700 c.f.s. In 1997, the rate of water flow was 70,500 c.f.s., which was the previous maximum, with a minimum value of 23,600 c.f.s. in 1962.

The amount of water within the river channel is also indicated by its measured stage. On August 12th, it was at 26.67 feet, according to Kevin Stamm, a senior hydrologic engineer with the U.S. Army Corps of Engineers offices at Omaha.

The water levels are due to large amounts of runoff from tributary streams below Gavins Point Dam, including the James River, Vermillion River, Big Sioux River and Little Sioux River, Stamm said. "Continuous rains have resulted in high runoff."

The current amount of water going southward along the Missouri, are contributing to an expected high extent of flow for the year, Stamm indicated. Once final details are available, the acre feet of water measured as flowing past the gauge site will probably be among the top three years on record, he said.

Greater rainfall has also contributed to their being standing water in what are normally cropland fields.

During June, there were 9.25" of rain as measured by the Omaha office of the National Weather Service. This is 5.30" departure from what is considered to be normal. A greater extent of precipitation continued in July, when a 6.32" total rainfall was 2.46" inches above the normal value of 3.86 inches.

With this amount of rainfall, the accumulated water has not drained away - despite the presence of ditches established by the local drainage district - but is gathered in low lying areas to an extent sufficient to create a variety of water-based habitats suitable for shore and water birds.

Water Habitats Attract Birds

"There has been an extraordinary benefit for birds this year" at Desoto and Boyer Chute National Wildlife Refuges, according to Tom Cox, manager of both areas. "We are getting water-based habitats which were historically prevalent."

Much of Boyer Chute NWR has been "under water," he said. More than 600 acres of the 4,400 acres of the designated refuge property have had standing water, and once the river flow decreases, about 25% of the refuge will retain standing water.

The water conditions now present provide several benefits, Cox said, including: creating ephemeral habitat for migratory ducks and other water-dependent birds, creating sedge meadows and helping to provide the wet soils conducive for the regeneration of the cottonwood forest, especially at Desoto refuge.

The flood conditions have meant a closure of Boyer Chute refuge several times during the past couple of months. The most recent closure started on August 1st, and continued at least through August 15th, when this article was posted.

Developing a new comprehensive conservation plan for the refuge is to be started near the end of August, and the high water conditions are providing new insights for developing wet habitat conditions on the refuge, Cox said. "Flooding is influencing the vegetation, and indicates how we might - in the future - let river flows help create plant communities."

The paved road between Nathan's Lake and County Road P51 into the refuge, have also been closed.

Extensive private property adjacent to refuge lands also have water present, especially in the area around the historic Horseshoe Lake. These flats - typically a corn or soybean field - have large expanses of wetlands of various sorts, which has attracted different species of birds. More than 600 acres of what is typically cropland is presently standing water in varying depths and extent, based on a visual evaluation and demarcation on an aerial photo of the region.

Partially flooded hayfield habitat used by shore and water birds, east of the Horseshoe Lakebed. Picture taken August 11, 2010.

Shorebirds on a flooded county road, west of the Boyer Chute NWR entrance. Picture taken August 12, 2010.

Floods at an Omaha Park

N.P. Dodge Park - a city of Omaha park - has been closed five times during the summer due to flooding, according to Randy Garlipp, the park caretaker. The first closure occurred right after Memorial Day, with the most recent occurrence starting in early August, with portions of the park reopened again around the 10th.

After each closure, the area was cleaned up, with an expectation that the excessive water conditions were over. This was obviously not the case. The most recent flooding has been the most prolonged.

"It's a nightmare," Garlipp said. About 150 acres of the 400 acre park were flooded during the most recent interval. Cleanup is progressing slowly, with efforts targeted to dealing with those areas typically used by the public, getting the most attention for restoration efforts.

Just to the north, crop lands were also flooded, as apparent on August 6th, as apparent from a vantage point on the bluffs on the east side of nearby Hummel Park.

As of August 12th, water remained high at Dodge Park, with the playground flooded, the nearby campground closed, shallow water over the road to the marina, with the boat dock access and parking lot under water, and the area adjacent to the river still inundated.

View of partially flooded corn field and north edge of N.P. Dodge Park. August 6, 2010 as taken from bluff at Hummel Park.

Formerly flooded campground at N.P. Dodge Park. Picture taken August 11, 2010.

"We've seen lots of herons in the camping area," Garlipp said. This area is typically a grass-covered area among cottonwood trees. Killdeer have also been prevalent. Earlier in the summer, a fledgling Barred Owl was found, and left in place after a call to the Raptor Recovery Center to inquire how to deal with the situation.

Garlipp noted that there were a lots of frogs about which this species of owl could pursue as a meal. The next morning, the owl was gone.

On August 11th, a Lesser Yellowlegs was noted foraging about a bit of remaining water at the campground, which seemed most suitable for Killdeer, rather than any other visitors.

The campground and play ground are expected to remain closed for the remainder of the 2010 season, according to a news article published on August 14th, with an expected loss of revenue which any campers would have had to pay to stay and camp.

Bird Variety of Horseshoe Lake Flats

A first report of the occurrence of avian variety was indicated by a message on the NEBirds forum, based upon a cursory, drive-by look on August 6th, along the roadside between Nathans Lake and the closed entrance to the Boyer Chute NWR.

Three focused visits on mornings of the 11-13th, indicated the presence of a great number of birds associated with the flooded crop fields in the same vicinity, primarily on private property. The site was designated as Horseshoe Lake Flats because of its association with the historic lake and to differentiate it from the nearby refuge property. This is a new place name as there is no other known name and the habitats are associated with the former oxbow lake of the river floodplain.

The most notable wetland habitats are east and north of the historic Horseshoe Lake, which is publicly owned, but was not surveyed as it is not readily accessible, and could not be viewed from the roadway vantage points.

Birds are immediately obvious starting at Nathan's Lake. Though there were few birds - perhaps a grebe or coot - upon the lakes' ample waters, there have been a bunch of Cliff Swallows about the bridge over the drainage channel on its northern edge. Upon passing this crest, the inundated fields are obvious towards the northeast.

While slowly going along in a northward manner on the hard-surface road - with shallow waters flowing across at one place or another, depending on the day - bird of a fine variety have been prevalent. As of mid-August, the greatest variety of species have been noted in a flooded hay field to the west of the road, south of Horseshoe Lake Lane, which is the address on the sign for the farmstead.

The diversity has been different during each visit, with some species seen each time, but others seen on only one occasion. There are numerous shorebirds - especially Killdeer with more than 100 present at times -and which includes more than 30 Great Blue Herons and numerous Great Egrets, as well as waterfowl such as Blue-winged Teal gathered on the flooded lowlands. Not only wetland-dependent species are congregating. Many Purple Martins have been noted on the wires near Nathans Lake, as well as northeast of the Horseshoe Lake Lane farmstead. A myriad of other swallows are also about, especially foraging above the waters which are apparently rich with bugs upon which the birds might capture with ease.

Among the tall grasses and similar spaces are the secretive Sedge Wrens, boisterous Dickcissels, Common Yellowthroats, with an occasional expression of the Song Sparrow and Field Sparrow.

The roiling waters this season about the diminished confines of Horseshoe Lake are now an appreciated haven. Whether expressive in flight or sublime while resting, each bit of bird life appreciates the liquid vistas. For the three days when the scene was considered, the watery realm was a haven of bird life, as indicated by the following composite list of what was seen at the scene. It was not a situation of August doldrums, but a vibrant place for birds when enough attention was directed towards seeing what was present.

  • Canada Goose: heard more than seen, but they were obviously present on the flats, as heard or seen in flight; also seen congregating while eating grass near the entrance to the marina at N.P. Dodge Park.
  • Blue-winged Teal: small bunches in flight above the waters of the lake flats
  • Northern Shoveler: more easily seen than any teal
  • Pied-billed Grebe: heard more than seen, while they make their way in the wetlands where they thrive.
  • American White Pelican: resting on the local runway for a plane.
  • Double-crested Cormorant: just a few about.
  • Great Blue Heron: prevalent on the bottoms, in numbers.
  • Great Egret: a bunch at one time yet relatively uncommon a few days later.
  • Cattle Egret: a few near the grazing horse and cow, south of the refuge entrance.
  • American Coot: just a couple among atop the water and among the vegetation.
  • Killdeer: not a "ton" as expressed by one observer, but since more than 100 were undoubtedly present, their abundance and obvious appreciation indicates the areas is most certainly suitable for their occurrence.
  • Spotted Sandpiper: heard.
  • Greater Yellowlegs: only a few have thus far appreciated the habitat suitable for them to forage.
  • Willet; a single bird noted on the north side of the closed entrance road to the Boyer Chute NWR headquarters. Justin Rink and I arrived on the scene, where I quickly proclaimed our arrival for the meeting which we were in no manner aware, but apparently included people from the refuge as well as the Washington County Road Department. The presence of multiple vehicles indicated something was happening, so my proclamation was based on conjecture, and was apparently confusing to the refuge men. The FWS guys did not know what bird they were looking upon across the flowing waters, so while my babble was underway, Justin made the obvious identification. Us two birders then noted two Great Egrets to the north, and both were an addition to the variety seen. We left the road situation discussions behind as we continued onward in our quest to look at birds of different places where water provides habitat.
  • Lesser Yellowlegs
  • Upland Sandpiper: only a couple seen on Friday morning.
  • Least Sandpiper: on the mud flats as well as being obvious upon the road when water flows occurred.
  • Baird's Sandpiper: it took some time to view this particular shorebird species, whose presence also indicated the suitability of the habitat for so many species.
  • Pectoral Sandpiper: subtly present.
  • Stilt Sandpiper: noted first because of the distinct coloration patterns in their plumage.
  • Buff-breasted Sandpiper: birder Rink located the few birds present, which were, with direct directions, found moving north through the somewhat barren ground of a portion of the formerly flooded hay field. This was a special find as it was species number 304 observed in Nebraska by master birder Rink. Their coloration and occurrence was distinctly subtle and certainly a wonderful occurrence.
  • Long-billed Dowitcher: a big bird with their long beak pressed into the mud.
  • Wilson's Snipe: subtle yet distinct.
  • Wilson's Phalarope: their fall plumage is very benign, but the flock was readily obvious as they stayed together whilst flying around.
  • Least Tern: notable because of their small size.
  • Black Tern: it took special focus to note their occurrence.
  • Common Tern: a subject of continued discussion, as seen and considered, then looked at again and heard and eventually identified with certainty as they continued to express they unique characteristics while resting at the water's edge and while calling and flying about the scene near our vantage point.
  • Forster's Tern: fall plumage characteristics provided the distinction needed to make a decision on this species' identification.
  • Mourning Dove: obvious during a focused look.
  • Belted Kingfisher: two perched on a wire, certainly looking for a fish to catch
  • Northern Flicker: on the lawn at the farm yard.
  • Eastern Kingbird: in the top of a tree in the vicinity of the place being observed.
  • Blue Jay: heard in the distance.
  • American Crow: heard.
  • Purple Martin: bunches on the wires
  • Northern Rough-winged Swallow: among the flying horde of swallows.
  • Bank Swallow: flitting about.
  • Cliff Swallow: many flying about in the aerial realm.
  • Barn Swallow: most notably around the farmstead.
  • Sedge Wren: very expressive yet secretive in the planted grasses of the refuge lands
  • American Robin: about the Horseshoe Lake Lane place.
  • European Starling: bunches about, including those which found the round hay bales a suitable roost, for some time or another.
  • Common Yellowthroat: calling in the places which they find are fine for them to occur.
  • Chipping Sparrow: occur because of suitable conifers.
  • Field Sparrow: call prevalent
  • Song Sparrow: also expressive in the vicinity
  • Indigo Bunting: also readily apparent based upon their musical expression
  • Dickcissel: easily apparent by their expression spread across the flats
  • Red-winged Blackbird: hither and yon among the scene, as their time is moving towards going elsewhere.
  • Common Grackle: just a few.
  • American Goldfinch: only a few heard if an observer's attention considers the entire spectrum of sounds across the landscape.

The birds which expressed their presence represents more than 50 species, each one heard and considered individually with enough attention to indicate a proper identification.

If water habitats on the flats endure as the autumnal migration season continues, there should be a great variety of species that can occur and be appreciated due to the prevalence of water on the flooded fields and inundated croplands near the Missouri River in Washington County, east of Fort Calhoun.

There are opportunities at this locale which might provide continued habitats for resident and migratory shore and water birds to occur. The planning for the future effort to be carried out for Boyer Chute NWR is an obvious effort which can be beneficial to providing water-based habitats, yet those results will be unknown for a few years, so the current situation is one to appreciate now for the presence of so many unique birds.

A Marbled Godwit was observed at the shorebird area on August 16th, by Matthew Cvetas, as reported on NEBirds. Also reported were Semipalmated Plover and a hundred Cattle Egrets. A similar number of Cattle Egret were noted on the 17th, along with a Black-bellied Plover.

Cattle Egrets at the Horseshoe Lake Flats. August 17, 2010.