A one year survey was conducted on birds that occur in the Sand Hills region of southern Holt County. The southern part of the county is basically south of O'Neill but with most field work taking place in the most southern portion of the county. Most of the information is for birds noted during 1990, though some earlier records are included.
The Blake Ranch had the most thorough notes since ranch chores were done here daily. Sites were visited on a periodic basis, typically once very ten days, from mid-February through November were done at Swan, Goose and Chain Lakes. Bruner Lake was visited just four times and information from here has been compared to birds noted historically (Blake and Ducey 1990). Records were kept of bird species occurrence and the number of some birds. A list for the region was kept by recording all species noted in the southern Holt County area.
The Holt County Region
Southern Holt county is subirrigated valleys and sandhills. "The subirrigated valleys are broad, nearly level to very gently sloping bottom lands along the Elkhorn River an its tributaries. The high water table in the area permits the growth of luxuriant stands of native grasses. The valleys merge through transitional areas of low rolling and hummocky topography with the rolling and hilly sandhills. The largest sandhills are mostly in the southwestern part of the county. The sandhills rise 10 to 200 feet or more above the valleys and swales. Small lakes and wet areas are in some valleys and swales. Blowouts are common throughout the sandhill areas. Perennial streams are small and slow moving, 4 to 5 feet in depth. Streamflow during dry periods is maintained by seepage of ground water into the stream channels. Most rainfall infiltrates the sandy soil, and there is little runoff," (Soil Conservation Service 1983:4-5).
Most lakes in Holt County are slightly alkaline and have an average depth of 1.2 meters (McCarraher 1977). Specific features of lakes visited for the bird survey, include: Overton Lake (55.5 ha (hectare), 136 ac (acres); maximum depth 2.0m (meters) and mean depth 1.1m), Bruner Lake (15.4 ha, 38 ac; depth 2.3 and 1.2m; medium alkalinity), Swan Lake (97.1 ha, 240 ac; depth 2.6 and 1.2m; slight alkalinity), Chain Lake (42.5 ha, 105 ac; depth 1.5 and 0.9m; slight alkalinity) and Goose Lake (102 ha, 252 ac.; depth 1.5 and 0.6m; slight alkalinity).
All wetland meadows are cut for hay each season. Areas of standing water in lower portions of meadows aren't hayed but the grass is cut from as much of the meadow area as possible. Hay is cut starting in July and may continue during for two months. Cattle graze the grasslands and create a variety of rangeland conditions. Areas cut for hay may also be grazed during the fall or winter.
There have two primary changes which have impacted habitats used by birds in Southern Holt County. Water drainage has occurred in lakes and streams. Grass Lake and Maurice Lake are now lakebeds used as hay meadows. Declines in exposed water levels have been caused by road ditches. "The area is not wet because the road ditches, which are lower than the land beside them, allows many low areas to drain and many other areas to drain more rapidly. The creeks used to spread out wide and flow through the valleys and had no channels. Roads have been a major factor in causing the channelization because the culverts and bridges narrow the streams and forces all the water to flow in one place," (1990: L Dubrovolny, in his 70s, to L.E. Blake, pers. comm.). Conversion of rangeland to irrigated cropland has also occurred throughout the county.
Specific Areas Birded
Visits to a variety of locations were made to gather bird records. This included the larger, primary lakes, an area ranch and notes kept during travels in the area. The wetlands, sandhills prairie and woody growth occur to different extents. Grassland is the most predominant habitat type and was present to some extent at each site visited.
It should be noted that the summer of 1989 was extremely dry in this region. Moisture was adequate in 1990 but there was no surplus moisture to fill areas that may have been wetter when moisture levels were greater. Due to dryer conditions, the water level in some lakes was lower. Some marshes and sloughs were completely dry. Of the lakes visited, Chain Lake was the most affected by lower moisture levels. One portion of this lake was completely dry and the remaining area of standing water covered fewer acres than it normally would.
Bruner Lake is predominantly open water with rushes growing on about one-half of the shoreline. Two small islands in the lake are covered with vegetation. A mix of rushes, slough grass and scrub willow covers the lowland next to the lake. Other features include an ash and mulberry shelterbelt about 0.5 mile southeast of the lake. A planting of young cedar trees and a few cottonwoods grow on the west side. Another shelterbelt, predominantly ash trees, and marsh is 1.5 miles to the southeast. The shelterbelts are not grazed by cattle but there is not much woody understory (Blake and Ducey 1990).
Swan Lake is predominantly open water. Willows grow along the north shore. There is a small area of cattails on the northeast part of the lake. A pine grove of about 120+ acres has been established on the flat land and hills north of the lake. Recreational fishing occurs on the lake. A paved road parallels the eastern half of the north shoreline.
The Blake Ranch area covers nine square miles (buildings in the southeast one-quarter of sec. 25 T26N R14W). The south fork of the Elkhorn River runs west to east through the center of the ranch. This stream may not have any water in dry years except for deeper holes which are eventually reduced to stagnant ponds. The western ranch is moderate-sized sandhill dunes and the eastern two-thirds is sub-irrigated meadow and pasture. There is a good growth of trees and shrubs around the ranch house. A mature grove of cottonwoods occurs in a grove and a shelterbelt along the road. Sightings in the trees at the ranch house and a feeder in the winter provide a constant record since they are made daily. Meadows are a combination of native species and introduced timothy, red top and clover. There are two small patches of corn grown in the ranch vicinity. One crop area has been abandoned and replanted with an introduced forage grass.
Chain Lake is isolated in the sandhills and all of the area is grazed. The lake mostly open water with little or no cover or emergent marsh along the shoreline. The surrounding ground is mostly sandhills prairie heavily grazed by cattle. A growth of mature cottonwood trees around an abandoned homestead occurs in three separate sites but overall covers less than 40 acres. There is no shrub or understory growth among the trees.
Goose Lake WMA is 349 acres is the lake with some areas of cattails a few acres in size with trees well developed at several places. The open water areas can be easily surveyed from the western shore line. A cottonwood grove, with a good growth of shrubs, of about 10-12 acres occurs on the northwest portion of the area. Willows grow at several places along the lake boundary. Bare sand areas on the west and northeast portions of the lake provide open areas for water and shore birds. Trees along the north shore provide a roost spot for birds such as Black-crowned Night Herons. A pump installed by the local natural resources district is used to provide supplemental water if levels need to be maintained. The lake has been regularly used in past summers for recreational boating, including water-skiing in the summer. Water skiing was not allowed in 1990 and the lake was chemically treated to kill fish prior to a restocking.
During the survey of southern Holt County, 202 species in 42 bird families were noted. The greatest number were at the Blake Ranch (143 species, 71% of 202 noted), with lesser numbers at Goose Lake WMA (117, 58%), Chain Lake (93, 46%), Swan Lake (90, 45%) and Bruner Lake (72, 36%) which basically had three summer visits. Though the number and intensity of observations influence the species list, it is apparent that no specific site had an overall majority of all the species noted for the survey.
The Blake Ranch has a higher number of noted species. The extent of bird notes from here would be higher, specific reasons include daily activities and awareness of bird activity. If a species came through quickly, but was seen at the Blake Ranch it was a recorded observation. A similar occurrence at the other survey sites would have been less likely to have been recorded. Winter feeding attracts species and the list for the Blake Ranch reflects this. Winter birds noted only at the Blake Ranch includes both kinglets, the Purple Finch and Common Redpoll. Other species noted only at Blake Ranch are Tennessee Warbler, American Redstart, Ovenbird, chat, grosbeaks, buntings and sparrows.
The Horned Grebe, Black-bellied Plover, Long-billed Curlew, Buff-breasted Sandpiper, Short-billed Dowitcher and Red-necked Phalarope were noted only in wetland habitats at Chain Lake. Based on the available, records, this indicates that Chain Lake has a greater diversity of water and shore birds due to its habitat conditions. Other species seen at a single site only include the Black-crowned Night Heron and Forester's Tern at Goose Lake. The Rock Dove was seen only at Bruner Lake. The Cliff Swallow occurred only at Swan Lake, near the small nesting colony.
Avian Guild Analysis
Avian guilds are useful for analyzing how birds relate to resources available in their environment (Landres 1983). A guild analysis can provide important information that indicates the ability of habitat zones to support populations of wildlife species (Verner 1984). For the birds of North America, the quild categories have been thoroughly explained and defined (De Graff et al. 1985).
For the Sand Hills region, the use of guilds can define zones of habitat used by bird species and the number of species that occur in a particular habitat zone. Both items can be useful in better understanding habitat use and occurrence of Sand Hills avifauna, perhaps helping to identify "indicator species" that can be used to evaluate changes in bird populations and to better understand habitat utilization.
Placing birds within the appropriate guilds allows a detailed analysis and comparison of the resources and habitats used by species. For this Holt County study, each species was assigned to an avian food preference and foraging guilds (Tables 1 and 2). Comparisons can then be made on habitat utilization and the variety of habitats used by species. Only those species noted at the five specific study sites are included in the guild analysis.
|Table 1. Summary of the food preference guilds of species at Select Holt County sites. Numbers may not equal the total number of species because the same species may be listed more than once if it is included in more than one guild class.|
|Preference Guild||Bruner||Swan||Blake||Chain||Goose||Overall Total|
|Table 2. Summary of the foraging guilds of species at select Holt County sites. Guilds are agganged from higher to lower elevations and from upland to lowland habitats. Numbers may not equal the total number of species because the same species may be listed more than once if it is included in more than one guild class.|
The least common species based on food preference are those in the mulluscovore guild, for birds which eat mollusks. The four species are the Semi-palmated Plover, Marbled Godwit, Virginia Rail and Ovenbird. The plover and godwit were seen at the four lake survey sites. The rail and ovenbird were noted only at the Blake Ranch. The vermivore guild, with a food type of earthworms, has the next lowest number of species. Species in this category are mostly shorebirds - the Black-bellied Plover, Least Sandpiper, Stilt Sandpiper and Common Snipe - and a single songbird, the American Robin which forages in very different habitat. More carnivores, the various raptors were seen at the Blake Ranch. More birds that eat crustaceans were noted at Chain Lake and Goose Lake that at the other three study sites. There are 19 species included in this category, but each of them is also classified in another food preference guild. Note of the survey sites has a record of all 19 species. Chain Lake has the highest number. All of the species are water or shorebirds, include the curlew seen only at Chain Lake, and the Sanderling and Western Sandpiper seen only at Chain and Goose lakes. The Great Egret and Green-backed Heron, included in this guild, were seen only at the Blake Ranch.
Based on foraging guilds there are more wetland guilds used by foraging birds in comparison to air and ground foraging sites. There are five categories and 18 different wetland foraging guilds. This includes the shoreline, mud, fresh-marsh and freshwater groups. There are five categories with 14 guilds for air and ground foraging guilds. This indicates greater utilization of aquatic habitats in comparison to upland habitat, especially if the air foraging guild is excluded.
Species in the air foraging guild include swallows, Common Nighthawk, American Kestrel and flycatchers that use vegetation as perches to sally forth and capture insects. Bark cleaners, the woodpeckers, were seen at several of the sites but only the White-Breasted Nuthatch and Brown Creeper at Blake Ranch. Upper-canopy foraging species include the orioles, Purple Finch and Red Crossbill. Vireos and warblers are the primary species in the upper-canopy gleaner guild.
Summer birds noted only at the Blake Ranch are the Yellow-Billed and Black-Billed Cuckoo which use lower canopy foliage for foraging and breeding. Other lower-canopy species include the Black-capped Chickadee, warblers and the American Goldfinch. The House Wren is a lower-canopy gleaner. Among the lower-canopy and ground guild are the Eastern Bluebird, Gray Catbird and Brown Thrasher. Short-Eared Owl was a ground hawker noted only at Blake Ranch. The only ground prober noted was the Common Snipe, but was seen at several of the survey sites.
Many species forage on ground prey. This group includes raptors and many songbirds in several families. Many sparrows noted in southern Holt County are part of both the ground forager and ground gleaner guilds. These two categories have the higher number of species. The Blake Ranch had the most sightings and number of species within these two categories.
Shoreline probers includes many notable species, such as the Long-billed Curlew (noted only at Chain Lake), Marbled Godwit, Sanderling, Willet, Semipalmated Plover, Stilt Sandpiper, Western and Least Sandpiper. The Spotted Sandpiper and Killdeer were common species noted at all survey sites. Among the shoreline gleaners, the Piping Plover was noted only at Swan Lake and the Black-bellied Plover was seen only at Chain Lake. Chain Lake had the highest number of species in both shoreline foraging guilds.
Species that forage in muddy habitats were some of the species noted less often during the survey. Only three species in this category - the Baird's Sandpiper, Common Snipe and the Short-billed Dowitcher, noted only at Chain Lake, were seen.
Among species that forage in fresh-marsh habitats were the Avocet at three sites visited and Sandhill Crane at two, most commonly flying overhead. The only fresh-marsh gleaner was the Marsh Wren and the only prober in this category was the Virginia Rail. The only species in the freshwater strainer guild is the Northern Shoveler.
Represented from the freshwater plunger and foot-plunger guild were two species at Chain Lake - the Forester's Fern and Belted Kingfisher. The Kingfisher was also noted at Swan Lake and the Blake Ranch. The only freshwater foot-plunger was the Bald Eagle, seen at Blake Ranch and Chain Lake, which had several birds during the winter.
Many of the freshwater bottom feeders are waterfowl such as the Lesser Scaup, Bufflehead, Hooded Merganser and Ruddy Duck. The several species of waterfowl noted from this guild indicate the quality of water in area lakes, specifically Swan and Goose Lakes, which supports the food base needed by this type of bird. Both of these lakes had greater numbers of freshwater bottom foraging waterfowl.
Although the guild analysis does indicate that for some foraging habitats, only a few species use a specific habitat type. The shoreline, mud and fresh-marsh guilds have a fewer number of species than the freshwater and uplands. Further analysis of avian guilds, including comparisons from different regions of the Sand Hills, is needed to provide additional data needed to evaluate species status.
The survey results indicate additional attention is needed for some species in southern Holt County and adjacent areas. Specifically there is a need to determine if and where the Northern Harrier is present, perhaps breeding, during the summer. The western boundary area of Holt County and into Rock County needs to be surveyed to determine the occurrence and range of Long-billed Curlews in the eastern Sand Hills.
- Blake, L.E. 1988. Connecticut warbler. Nebraska Bird Review 56:99.
- Blake, L.E. 1989a. Sprague's pipit. Nebraska Bird Review 57:32.
- Blake, L.E. 1989b. Winter wren. Nebraska Bird Review 57:96.
- Blake, L.E. 1989c. Black-headed grosbeak. Nebraska Bird Review 57:96.
- Blake, L.E. 1990a. Nesting trumpeter swans. Nebraska Bird Review 58:106.
- Blake, L.E. 1990b. Buff-breasted sandpipers. Nebraska Bird Review58:107.
- Blake, L.E. and J.E. Ducey. 1990. A comparison of historic and modern birdlife at an eastern Sand Hills lake in Nebraska. Nebraska Bird Review 58:100-104.
- De Graaf, R.M., N.G. Tilghman and S.H. Anderson. 1985. Foraging guilds of North American birds. Environmental Management 9:493-536.
- Landres, P.B. 1983. Use of the guild concept in environmental impact assessment. Environmental Management 7:393-398.
- McCarraher, D. B. 1977. Nebraska's Sandhills Lakes. Nebraska Game and Parks Commission, Lincoln.
- Soil Conservation Service. 1983. Soil survey of Holt County, Nebraska. Soil Conservation Service, Lincoln.
- Verner, J. 1984. The guild concept applied to management of bird populations. Environmental Management 8: 1-14.
- Blake, L.E. 1989a. Sprague's pipit. Nebraska Bird Review 57:32.