Riparian Bird Communities of the Great Plains

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RIPARIAN BIRD COMMUNITIES OF THE GREAT PLAINS

Allen A. Tubbs

Lecturer, Division of Biology Emporia State University Emporia, Kansas 66801

ABSTRACT

One hundred thirty-six birds utililizing riparian communities in the Great Plains are identified and categorized. Breeding birds restricted to riparian vegetation may outnumber obligates of other grassland communities sevenfold. Sensitive and other decreasing species are discussed. Grazing, water diversion, and land conversion are the most destructive impacts in the region. Wood-harvesting in riparian habitat is an increasing and potentially disastrous practice. Research needs and management approaches are suggested.

KEYWORDS: birds, riparian habitat, grasslands, management

INTRODUCTION

Riparian ecosystems have been found to be among the most productive and valuable wildlife habitats wherever they occur (Hubbard 1977, Sands and Howe 1977, Fitzgerald 1978, Schrupp 1978). Their importance for birds in the western United States has been well established (Carothers and Johnson 1975, Gaines 1977, Wauer 1977, Bull 1978). Riparian habitat is most critical in arid and semi-arid environments of the region. Coincidentally, these areas are under the greatest pressure from human activity, which unfortunately is rarely favorable to conserving such habitat and its avifauna. The riparian ecosystems of the Southwest have been particularly affected due to a large increase in the human population and its demands for water and other resources in the immediate environment and have received some recent ornithological attention (Johnson 1972, Carothers et al. 1974, Johnson and Jones 1977, Anderson and Ohmart 1979). Riparian bird communities of the Great Basin Desert and Great Plains have been less extensively studied (Beidleman 1954, Crouch 1961, Kindschy 1978). The intent of this paper is to examine the riparian portion of the Great Plains, identify and categorize its dependent avifauna, survey negative impacts on such habitat, and suggest ways to help manage these areas for birds.

419 Definition of Riparian

Riparian habitat could be broadly defined to include all vegetation adjacent to water, however the scope of this consideration will concentrate on woody vegetation along drainage systems, flood plains, and on the banks of lakes and reservoirs of the interior grasslands. Marshes and potholes prevalent in the northern prairies are an integral part of those communities and should be more appropriately discussed in their management.

Description of Area

The Great Plains extends from southcentral Canada southward through the Dakotas, eastern Montana and Wyoming, Nebraska, Kansas, eastern Colorado, western Oklahoma, the panhandle of Texas, and northeastern New Mexico. The area covered by Johnsgard (1979) from 49° latitude south to the Red River separating Oklahoma and Texas, then west from the 95th meridian to the 104th will be treated here. This major portion of the extant plains encompasses 502,000 square miles, of which about 13 percent is deciduous hardwood forest (Johnsgard 1979). The bulk of this forest occurs as extensions of the eastern deciduous forest into the plains states. The quantity of riparian habitat in this vast expanse of grassland (much converted to agriculture) is hard to ascertain. Perhaps an indirect assumption of 1-3% based on Johnsgard's (1979) figure of 1% surface water and the known riparian vegetation of other western states would be a reasonable estimate. Exclusive of impoundments, Kuchler (1964) termed the hardwood dominated communities of a riparian nature across the Great Plains, the Northern Floodplain Forest. The rivers and streams of the western plains are bordered and dominated by cottonwood-willow (Populus-Salix) communities, while the eastern portions also support elm (Ulmus), oak (Quercus), hackberry (Celtis), green ash (Fraxinus), Kentucky coffee (Gy~adus), box elder (Acer), and other tree species. Avian communities of the cottonwood-willow river bottoms in eastern Colorado are among the few riparian ecosystems of the plains that have been studied from a conservation or management perspective (Beidleman 1954, Botorff 1974, Fitzgerald 1978). Other information generally must be gleaned from single species accounts, surveys, and breeding or winter bird counts.

IDENTIFICATION AND ECOLOGICAL ANALYSIS OF GRASSLAND RIPARIAN BIRDS

One must know what species populations breed, migrate or winter in a particular avian community to manage it. The identification of grassland riparian birds is complicated by the fact most authors (Johnston 1964, Rising 1974, Johnsgard 1979) classify birds of the Great Plains states as woodland, limnic, or xeric (Table 1) and emphasize only breeding birds.

Table 1. An ecological analysis of the breeding birds of the Great Plains. Woodland Limnic Grassland Xeric Misc. Total No. % No. % No. % No. % No. % Western Kansas 63 46 31 22 32 23 ---- 12 9 138 (Rising 1974) (combined) State of Kansas 101 58 36 21 23 13 3 2 11 6 174 (Johnston 1964) Great Plains 164 51 72 22 36 11 15 4 38 12 325 (Johnsgard 1979)

420 Breeding Birds

Only woodland and limnic groups contain species that could be considered riprian. Birds of these two ecological affinities constitute 73% (236 sp.) of the 325 birds which have bred in the Great Plains at least once (Johnsgard 1979). Eleven per cent (36 sp.) are restricted to grassland per se, 4% (15 sp.) to xeric communi ties, and 12% (38 sp.) of a miscelleneous category. Many woodland species are not restricted to riparian habitat, e.g., American Kestrel, Bobwhite, Mourning Dove, Eastern Kingbird, Blue Grosbeak, whereas a few of the limnic types are obligate riparian nesters, e.g., herons, egrets, and Belted Kingfisher. Table 2 lists birds that commonly reside, breed, or winter in riparian vegetation in the Great Plains.

Table 2. Riparian Birds of the Great Plains (Peterson 1947, Robbins et al. 1966, Johnsgard 1979) Year-round Residents Breeding only Winter only Great Blue Heron *Double-crested Cormorant Goshawk Wood Duck Great Egret Bald Eagle Common Merganser Snowy Egret MOuntain Chickadee Hooded Merganser Cattle Egret Red-breasted Nuthatch *Cooper's Hawk Little Blue Heron Brown Creeper *Sharp-shinned Hawk Green Heron Winter Wren Red-tailed Hawk *Black-crowned Night Heron Townsend's Solitaire Golden Eagle Yellow-crowned Night Heron Golden-crowned Kinglet Peregrine Falcon Turkey Vulture Ruby-crowned Kinglet *Merlin *Black Vulture Rusty Blackbird *American Kestrel Mississippi Kite Purple Finch Bobwhite American Woodcock Dark-eyed Junco Turkey Spotted Sandpiper Tree Sparrow Ring-necked Pheasant *Yellow-billed Cuckoo Harris' Sparrow Hourning Dove *Black-billed Cuckoo White-crowned Sparrow *Barn Owl Chuck-will's Widow White-throated Sparrow Screech Owl Whip-poor-will Fox Sparrow Great-Horned Owl *Ruby-throated Hummingbird Lincoln's Sparrow Barred Owl Scissor-tailed Flycatcher Swamp Sparrow Long-eared Owl Eastern Kingbird Saw-whet. Owl Western Kingbird Total - 19 Belted Kingfisher Great-crested Flycatcher Common Flicker Ash-throated Flycatcher Pileated Woodpecker Eastern Phoebe Red-bellied Woodpecker Willow Flycatcher Golden-fronted Woodpecker Acadian Flycatcher Ladder-backed Woodpecker Least Flycatcher *Red-headed Woodpecker Eastern Wood Pewee *Lewis' Woodpecker Western Wood Pewee Yellow-bellied Sapsucker Tree Swallow *Hairy Woodpecker *Purple Martin Downy Woodpecker House Wren Blue Jay Gray Catbird Black-billed Magpie Wood Thrush Common Crow Veery Black-capped Chickadee Blue-gray Gnatcatcher Carolina Chickadee Black-capped Vireo Tufted Titmouse White-eyed Vireo White-breasted Nuthatch *Bell's Vireo

421 *Bewick' s Wren Yellow-throated Vireo Carolina Wren Red-eyed Vireo Northern Mockingbird *Warbling Vireo Brown Thrasher Black and White Warbler American Robin Prothonotary Warbler *Eastern Bluebird *Yellow Warbler Cedar Waxwing Ovenbird European Starling Louisiana Waterthrush House Sparrow Common Yellowthroat Red-winged Blackbird *Yellow-breasted Chat Common Grackle Hooded Warbler Brown-headed Cowbird Kentucky Warbler Cardinal American Redstart Pine Siskin Orchard Oriole American Goldfinch Northern Oriole Rufous-sided Towhee Scarlet Tanager Song Sparrow Rose-breasted Grosbeak \· Black-headed Grosbeak 'Dotal - 56 Blue Grosbeak Indigo Bunting Lazuli Bunting Painted Bunting Total - 61 *Blue List (Arbib 1978)

The 117 species listed as year-round or breeding only, account for 45% of the 260 regular breeders Johnsgard (1979) documented for the region. Eastern deciduous forest species that normally don't venture out onto the plains, even via the flood plain corridors, or only rarely breed in the region (e.g., Red-shouldered Hawk, Golden-winged warbler, Evening Grosbeak) are not included in this compilation. It should be noted that 51% of the birds occupying the primarily grassland communities (which cover over 80% of the land area) are woodland or forest species (Table 1). This is an impressive statistic as woodlands and forests account for only about 15% of the Great Plains surface area. Johnston (1964) reported 58% of the birds of Kansas to be of a woodland habitat affinity and listed 21 species of eastern decid uous forest birds which occur in western Kansas only along river drainages. Rising (1974) stated "the majority of birds that breed or probably breed in western Kansas could be ecologically classified as woodland". The presence of these woodland birds in the plains is almost completely due to the existence of riparian habitat and points out the need for its conservation.

Although none of the Great Plains riparian birds is endemic, they greatly out number any nonriparian grouping. This is especially evident in the western portions of the grasslands. Ports (1979) in an ecological study of the birds of Morton County, Kansas, found 58 species in one or more of four communities. Forty of these inhabited riparian vegetation with lesser numbers in each of the other three non riparian study plots (Table 3). Of the 25 restricted species, 17 were riparian.

422 Table 3. A habitat analysis of the birds of Morton County, Kansas, summer 1979 Community Species Restricted No. % No. % Riparian 40 69 17 68 Short grass 33 57 2 8 Sagebrush 31 53 3 12 Agricultural 21 36 3 12

Totals 58 = N 25 100 . *raw data from Ports 1979

In a comparison of breeding bird census results, Ports (1979) reported that breeding bird density, species diversity, species richness, and number of individuals all were much higher in a riparian cottonwood-salt cedar plot than in nearby nonriparian plots (Table 4).

Table 4. Avian results for four study plots, Morton County, Kansas. (Ports 1979) Results Riparian Shortgrass Burned Sagebrush Breeding Study Plot Prairie Sagebrush Weedy Forb Bird Census Cottonwood Buffalo Sand drop Pasture Results Salt Cedar Grass-Blue seed Woodland Grama Pasture Density, Breeding 274 150 28 38 Birds/40 ha. Total Number of Species 22 10 11 13 Number of Breeding 14 5 4 5 Species Species Diversity H 2.39 1.63 2.15 2.19 Richness s-1 8.5 4.09 5.95 7.1 ION Evenness H 1.78 1. 63 2-06 1.47 lo S Number of Individuals 299 161 48 50 May 23, 30 May 29, June May 26, June May 27, June Census June 9, 10, 5' 11' 12' 4' 14, 18' 20 3, 9, 10, 13 Dates 14 13, 19

423 Other breeding bird densities for Great Plains riparian communities range from 137 to 748 individuals per 40 hectares (Table 5). Almost all riparian censuses are higher than other grassland communities and are similar to or greater than breeding bird densities of the eastern deciduous forest.

Table 5. Breeding Bird Densities for Great Plains Riparian Communities Connnunity Location No. Species Breeding Birds/40 ha. (reference) Cottonwood-willow Weld Co., co 20 137 (Sawver and Sawyer 1977 :82) Black Walnut, Hackberry Lyon Co., KS 31 254 Green Ash (Sawyer and Sawyer 1977:81) Cottonwood-salt cedar Morton Co. , KS 22 274 (Ports 1979) Cottonwood-willow Logan Co., CO 187 341-432 Beidleman 1978) (year-round) (year-round} Cottonwood-willow Jefferson Co., co 25 469-748 (Sawyer and Sawyer (incl. colonial- 1977:81-82) herons) Open Cottonwood Weld/Morgan Co., co 81 525 (Fitzgerald 1978) Mixed willow-cottonwood Weld/Morgan Co., CO 89 589 (Fitzgerald 1978)

Winter Birds

Aside from Christmas counts and Bald Eagle surveys, there is a dearth of infor mation on birds wintering in riparian ecosystems of the Great Plains. At least nineteen species are known to occur in riparian habitat of the area of consideration only during the winter (Table 2). These added to the 56 year round residents gives a winter total of 75 possible species. Winter densities are still high with up to 232/40 ha. reported (Sawyer 1974). Many of these birds would perish without ' riparian vegetation for cover and food during the severe winters of the northern plains.

The Bald Eagle is the only endangered bird utilizing grassland riparian habitat to any significant extent. A Bureau of Reclamation survey in Kansas and Nebraska (Busch 1979) showed Bald Eagles to be wintering in increasing numbers on several reservoirs. These riparian habitats provide a waterfowl prey-base and roost trees, and are possibly tied to higher Bald Eagle counts.

Dickson (1978) reported higher numbers of wintering birds in east Texas bottom land hardwoods than in adjacent stands. Other authors (Anderson and Ohmart 1979) found birds reacted less to habitat structure in summer than other times, indicating ·,. _ .. winter and migrating birds may need more management.

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424 Migration, Dispersal, and Gene Flow

Many investigators have noted the value of riparian habitat as hospitable avenues for the migration or dispersal of birds across grasslands and deserts (Johnston 1964, Gaines 1977, Stevens et al. 1977, Bull 1978). The percentage of eastern birds (about 50% of Table 2) breeding in the Great Plains attests to the importance of th~ floodplain forests which allows for their westward expansion. Rising (1974) identified the eastern component "moving into" Kansas as woodland and edge species, while those entering from the west were dry woodland types. Black billed Magpies and Scrub Jays are examples of birds previously isolated from Great Plains grassland communities which have entered the region via riparian vegetation (Johnston 1964).

Riparian corridors have been shown to be of great importance for gene flow and hybridization between eastern and western relatives, e.g., flickers, orioles, grosbeaks, and buntings (West 1962, Johnston 1964, Sibley and Short 1964).

Numbers of migrants appear to be very high in riparian communities. Stevens et al. (1977) reported riparian plots to contain over ten times the number of migrant passerine species as adjacent nonriparian plots and identified several para meters which influence migrant use of riparian habitats. Although not a riparian species as defined here, the Lesser Sandhill Crane and its endangered relative, the Whooping Crane, utilize various riparian sites across the Great Plains in their annual migrations. The large staging area in the vicinity of Kearney, Nebraska, has received much publicity and may be threatened by water demands on the upper forks of the Platte River (Frith 1974, Aronson and Ellis 1979). The value of riparian habitat to migrants and dispersers should be incorporated into management plans for flood plain forests.

Sensitive Species

All grassland riparian birds occur outside the plains region, however, they are all "sensitive" in that they would rarely breed in the area without riparian habitat. It also must be remembered that many have been permanently pushed from portions of their original range as that habitat was decimated.

Cavity-nesters due to their rather specific nest-site selection and territo riality are sensitive in almost all habitats. The harvesting of older trees and clearing .of snags have severely reduced the populations of some birds (Scott et al. 1977). Thirty-five cavity-nesters reside in the Great Plains primarily in riparian habitat (Table 6).

Table 6. Cavity-nesting Birds of the Great Plains (Scott et al. 1977, Harrison 1978) Primary Nesters Secondary or Natural Nesters Occasional Nesters *Common Flicker Wood Duck Common Merganser Pileated Woodpecker Hooded Merganser Turkey Vulture *Red-bellied Woodpecker American Kestrel Merlin Golden-fronted Woodpecker Screech Owl Great-horned Owl *Red-headed Woodpecker Saw-whet Owl Barn Owl Lewis' Woodpecker Great-crested FlycatthE:!t. Barred Owl Yellow-bellied Sapsucker Ash-throated Flycatcher *House Wren Hairy Woodpecker Tree Swallow Bewick's Wren *Downy Woodpecker Purple Martin Carolina Wren *Black-capped Chickadee *Starling

425 Carolina Chickadee House Sparrow Tufted Titmouse White-breasted Nuthatch Eastern Bluebird Prothonotary Warbler *indicates low tolerance to preferred habitat alteration (Stauffer and Best 1980)

Eight of these are on the 1979 Blue List (Arbib 1978) of birds decreasing across the country. The primary excavators would seem to be an obvious choice for featured species management. Their demise would deprive many obligate secondary nesters of homes, increase competition for the few available sites, and promote declines. or extirpation of some species. The inclusion of three woodpeckers on the latest Blue List suggests imminent danger and the need for immediate research. Stauffer and Best (1980) found the Red-headed Woodpecker, Common Flicker, Red-bellied Woodpecker, and Downy Woodpecker to have a low tolerance to habitat alteration. There are indi cations that migratory cavity-nesters are less easily managed than year-round residents (von Haartman 1968).

Twelve riparian birds nesting in other than cavities are also on the 1979 Blue List (Table 2). Riparian birds of Kansas definitely decreasing are the Eastern Wood Pee Wee, Carolina Wren, and Orchard Oriole; those possibly decreasing are the Amer ican Kestrel, Scissor-tailed Flycatcher, Eastern Bluebird, and Blue Grosbeak (Zimmerman 1979). Three peripheral species breeding in grassland riparian habitat have been listed by the Kansas Fish and Game Commission as in need of conservation; the Tree Swallow, Black-capped Vireo, and Prairie Warbler. Studies in Iowan riparian communities classify the Wood Thrush, Blue-gray Gnatcatcher, Ovenbird, Scarlet Tanager, and Rufous-sided Towhee as intolerant to habitat alteration (Stauffer and Best 1980). The same authors described the Warbling Vireo and Yellow Warbler as having a low tolerance. There is a definite need to identify and study sensitive species in the riparian areas of the grasslands.

IMPACTS ON RIPARIAN VEGETATION AND BIRDS

Recent symposia have dealt with the various impacts of human activity on riparian habitat (Johnson and Jones 1977, Graul and Bissell 1978, U.S.D.A. Forest Service 1978). Impacts on Great Plains riparian communities are similar to those in other regions. Two hundred fifty thousand acres of riparian habitat are lost annu ally in the United States (McCormick 1978). Grazing, water use practices, and land conversion are the most widespread and destructive activities in the plains area.

Grazing

When done properly, the grazing of domestic livestock on grasslands is generally compatible with birdlife and may even increase the numbers of some species, although some of these birds may be detrimental to others (e.g., cowbirds and starlings). The effects of overgrazing are obvious in the American west and usually quite harmful to all wildlife. The attractiveness of water in the grasslands to cattle causes major damage to riparian understory vegetation. The tendancy for livestock to congregate and linger around ponds and stream banks results in the elimination of food and cover plants, reduces nest-sites and habitat diversity, and increases soil erosion (Buttery and Shields 1975, Behnke 1978, Crouch 1978, Kindschy 1978). Crouch (1978) reported a 50% loss of cottonwoods over 18 years in a grazed northeastern Colorado bottomland. No grazing system has been shown to be effective in protecting riparian vegetation (Behnke 1979). Kindschy (1978) recommended the removal of livestock

426 grazing from riparian communities. Overgrazing of grasslands supplying riparian systems can modify runoff patterns and significantly reduce stream volumes or ground water supplies (Johnson et al. 1977). Fencing, reduction of numbers in an area, and temporal separations can all reduce the severity of damage where cattle must have access to water. In the western Great Plains, riparian vegetation can recover in 5-7 years when protected from livestock (Crouch 1978, Behnke 1979).

Water Use Practices

Two practices stand out which reduce water flow and hence, riparian vegetation in the Great Plains. The first is the intensive pumping of ground water for irri gation in western Nebraska, Kansas, and Oklahoma. The second is the channelization and ~ammingof streams for flood control. Some habitat is created by reserv~irs which benefits certain birds, but dams are ecologically short-lived and disruptive even tually silting in while reducing water flow downstream. Channelization can be used as a management tool to increase or optimize meandering in some revegetation projects (Kochman 1979) but is usually harmful to wildlife. Channelization on the Missouri River, for example, has reduced island acreage from 24,000 acres in 1879 to only 400 acres in 1954 in the lower 500 miles of the river (Mathews 1980). Most land adjacent to water is privately owned with legal rights to a certain amount of that water. This coupled with the economics of irrigation usually necessitates litigation to protect critical riparian habitats and their wildlife.

Land Conversion

Land conversion generally accompani~s water diversion. Dickson (1978) believed the main threat to birds inhabiting bottomland hardwoods was the conversion of these forests to farms and reservoirs. In eastern Colorado agriculture is the primary user of riparian areas, converting and using floodplains right up to the river in some areas (Mustard 1978). About 82% of the channelized portion of the Missouri River has been put into agricultural cropland (Mathews 1980). This encroachment is occurring on both private and public lands. Kochenderfer (1970) recommended that buffer zones be retained between harvest operations in the Appalachiansto maintain water temper ature, water quality, stream channel integrity, and the associated riparian vege tation. This practice should be promoted in the plains region also. A 20 foot buffer zone has been suggested as minimal in Colorado stream relocation projects (Kochman 1979).

Wood-cutting

The great increase in the cost of petroleum fuels has brought the haphazard cutting of trees to epidemic proportions everywhere. The floodplain forest of the Great Plains is one of the communities that can least tolerate this assault. Thou sands of acres of the very important cottonwood stands along the Arkansas and Platte River drainage systems have recently been butchered to supply southern pulp mills (Borden 1978). This destruction can result in a significant or total loss of avian species from cottonwood-willow woodland. Beidleman (1978) reported a fourfold decrease in spring species, a threefold decrease in wintering birds, a 50-65% decrease in Mourning Doves, Black-billed Magpies, and House Wrens, and the total elimination of Dark-eyed Juncos and Black-capped Chickadees in a highly productive eastern Colorado cottonwood-willow community that was destroyed to a fringe only. Stevens (1980) has located 3009 Great Blue Heron nests in 76 colonies in Kansas which are in cottonwoods in the western part of the state, sycamores in the eastern portion. When nest and surrounding trees were progressively ctit over a three year period in Butler County, Kansas, there was a corresponding decrease in the number of heron nests. The colony eventually disappeared. Cavity-nesters are especially vulnerable to mature tree or snag removal.

427 Tree density and diversity must also be maintained. In an Arizona study, when tree density was reduced 44%, breeding bird pairs dropped 28%. When tree density was decreased to 78%, bird pairs decreased to 54% of normal (Carothers et al. 1974). Stauffer and Best (1980) found sapling/tree species richness and size, snag size, and vertical stratification vegetation to be most related to bird species abundance in riparian c.ommunities of Western Iowa. This suggests very selective cutting of tree species and sizes in the nearby plains counterparts to maintain avian populations. Borden (1978) suggested forest-type management through state agencies with federal assistance as the only reasonable way to help landowners and maintain these extremely valuable trees and their associated wildlife. Unregulated tree-harvesting must be curtailed.·

Recreational Activities

In general recreational use is not as destructive and irreversible in grass land riparian communities as it is in other biomes. It'smore a matter of too little public land concentrating too many users to a few small areas. Of course the problem is more severe nearer urban and suburban locales. Many recreational activities such as hiking, jogging, or bird watching are quite amenable to riparian management. Fishing and hunting in themselves are not greatly harmful, but the vehicles, especially four-wheel drive, that carry the sportsmen can and do cause substantial damage in some areas. Solutions are to restrict vehicle access and to acquire more public land, perhaps partially by way of a public use fee.

Sand and Gravel Mining, Road-building, and Fire

Good discussions of the effects of sand and gravel mining and subsequent reclamation attempts in cotton~ood-willow riparian communities can be found in Graul and Bissel (1978). This activity is usually associated with road-building and/or the expansion of suburbs into the grasslands. Because road construction generally parallels streams and rivers, riparian vegetation is often destroyed or deprived of water. Once roads are well established there is little additional impact with the exceptions of "improvements" and human traffic.

Fire can be a positive or negative factor in the maintenance of quality riparian habitat. Grass fires today are usually controlled operations aimed at maintaining high quality forage and rarely destroy large portions of riparian vegetation. The irregular burn patterns into riparian communities may increase avian diversity by creating a maximum "edge effect" (Kindschy 1978). On the other hand extensive fires can reduce nest-sites for middle and low shrub nesters, resulting in a decrease in bird species diversity (Buttery and Shields 1975).

The impacts of sand and gravel m1n1ng, road-building, and fire can be severe in some locales and may have t~ be considered in management procedures, but usually are minor in comparison to grazing, water diversion, land conversion, wood-cutting, and to a lesser extent, recreational activities.

MANAGEMENT RECOMMENDATIONS

1. Riparian habitat in the Great Plains must be identified and classified in a manner similar to Pase and Layser (1977) so managers will know what they have to work with.

2. There is a real need for ecological tolerance studies for breeding, wintering, and migrating birds in riparian habitat of the plains region. Studies along the lines of Stauffer and Best (1980) would be appropriate and valuable for managers.

428 Some parameters to consider are: minimum width of vegetational belts; tree density, species diversity, and age class; horizontal {topography) structure; and vertical (vegetative) structure.

3. A determination of sensitive species (rare birds, isolated populations, or colonial nesters) and their requirements (old trees, snags) must be made. These birds may require special treatment, sometimes at the expense of other species, but if the other birds are ubiquitous, consequences may be negligible.

4. In general the enhancement of habitat patchiness and edge will create more species diversity and contribute to ecosystem integrity which the manager should strive for.

5. Migratory corridors and islands should be maintained to prevent the interruption of gene flow, dispersal, and migratory patterns. The retention of buffer zones to human activity will help to achieve this desirable goal.

6. Livestock grazing must be more closely regulated and even eliminated in some areas if riparian vegetation and its dependent birds are to be preserved. Complete protection may be necessary for some years to allow badly abused habitat to recover.

7. Channelization and other flood control or water salvage practices which decrease riparian vegetation must be discouraged or stopped. Litigation may be necessary in many situations.

8. Landowners must be given incentives (tax benefits or state/federal aid, etc.) to encourage the retention of riparian vegetation and slow its conversion to agricultural uses. A landowner-manager cooperative program may be feasible.

9. Recreation in critical or sensitive areas should be limited to nonconsumptive or low-impact type activities. More public land is needed in the plains states but costs are high as most floodplain is rich farmland.

10. Landowners must be educated to the future consequences of extensive tree removal and haphazard tree-cutting. Wood-harvesting should be prohibited in public areas.

11. The effects of m~n~ng and road-building should be mitigated to prevent a negative change in riparian communities.

LITERATURE CITED

Anderson, Bertin W., and Robert D. Ohmart. 1979. Riparian revegetation: an approach to mitigating for a disappearing habitat in the Southwest. In Proc. The Mitigation Symposium. p 481-487. USDA For. Serv. Gen. Tech. Rep. RM-65, Rocky Mt. For. and Range Exp. Sta., Fort Collins, Colorado. Arbib, R. 1978. The Blue List for 1979. Am. Birds 32(6):1106-1113. Aronson, John G., and Scott L. Ellis. 1979. Monitoring, maintenance, rehabilitation and enhancement of critical Whooping Crane habitat, Platte River, Nebraska. In Proc. the Mitigation Symposium. p. 168-180. USDA For. Serv. Gen. Tee~ Rep. RM-65. Rocky Mt. For. and Range Exp. Sta., Fort Collins, Colorado.

429 Behnke, Robert J. 1978. Grazing and the riparian zone: impact on aquatic values. In Lowland river and stream habitat in Colorado: a symposium. p. 126-13?.. Colo-.-Chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Behnke, Robert J. 1979. Values and protection of riparian ecosystems. In Proc. The Mitigation Symposium. p. 164-167. USDA For. Serv. Gen. Tech. Rep. RM-65, Rocky Mt. For. and Range Exp. Stn., Fort Collins, Colorado. Beidleman, Richard G. 1954. The cottonwood riverbottom community as a vertebrate habitat. Ph.D. Thesis, Univ. of Colorado, Boulder. 415 p. Beidleman, Richard G. 1978. The cottonwood-willow riparian ecosystem as a vertebrate habitat, with particular reference to birds. In Lowland river and stream habitat in Coiorado: a symposium. p. 172-195. Colo.-chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Borden, Thomas B. 1978. Cottonwood as a crop in Colorado. In Lowland river and stream habitat in Colorado: a symposium. p. 114-117. Colo. Chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Botorff, R. L. 1974. Cottonwood habitat for birds in Colorado. Am. Birds 28(6):975-979. Bull, Evelyn L. 1978. Specialized habitat requirements of birds: snag management, old growth, and riparian habitat. In Proc. Workshop on nongame bird habitat management in the coniferous forests of the western United States. p. 72-84. USDA For. Serv. Gen. Tech. Rep. PNW-64, Pac. NW For. and Range Exp. Stn., Portland, Oregon. Busch, David E. 1979. The Bald Eagle and the Bureau of Reclamation in Kansas and Nebraska. In Abstracts of the sixtieth annual meeting of the Wilson Ornithological Society, Omaha, Nebraska. Buttery, Robert F., and Paul W. Shields. 1975. Range management practices and bird habitat values. In Proc. Symposium on management of forest and range habitats for nongame birds. p. 183-189. USDA For. Serv. Gen. Tech. Rep. W0-1, Washington, D.C. Carothers, Steven W., R. Roy Johnson, and S. W. Aitchison. 1974. Population structure and social organization of southwestern riparian birds. Am. Zool. 14:97-108. Carothers, Steven W., and R. Roy Johnson. 1975. Water management practices and their effects on nongame birds in range habitats. In Proc. symposium on management of forest and range habitats for nongame birds. p. 210-222. USDA For. Serv. Gen. Tech. Rep. W0-1, Washington, D.C. Crouch, Glen L. 1961. Wildlife populations and habitat conditions on grazed and ungrazed bottom lands in Logan County, Colorado. M.S. Thesis, Colorado State University, Fort Collins. 329p. Crouch, Glen L. 1978. Effects of protection from livestock grazin~ on a bottomland wildlife habitat in northeastern Colorado. In Lowland river and stream habitat in Colorado: a symposium. p. 118-125.--Colo. Chap. Wildl. Soc. and Colo. Audubon Council. Dickson, James G. 1978. Forest bird communities of the bottomland hardwoods. In Proc. Workshop management of Southern forests for nongame birds. p. 66-7~ USDA For. Serv. Gen. Tech. Rep. SE-14, Southeastern For. Exp. Stn., Asheville, North Carolina.

430 Fitzgerald, James P. 1978. Vertebrate associations in plant communities along the South Platte River in northeastern Colorado. In Lowland river and stream habitat in Colorado: a symposium. p. 73-88. Colo. Chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Frith, Charles. 1974. The ecology of the Platte River as related to sandhill cranes and other waterfowl in Southcentral Nebraska. M.S. Thesis. Kearney State College, Kearney, NE. 115 p. Gaines, David A. 1977. The valley riparian forests of California: their importance to bird populations. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 107-110. USDA For. Serv. Gen. Tech. Rep. RM-43; Rocky Mt. For. and Range Exp. Stn., Fort Collins, Colorado. Graul, Walter D., and Steven J. Bissell. 1978. Lowland river and stream habitat in Colorado: a symposium. Colo. Chap. Wildl. Soc. and Colo. Audubon Council. 195 p. Harrison, Colin. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. 416 p. Collins, New York. Hubbard, John P. 1977. Importance of riparian ecosystems: Biotic considerations. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 14-18. USDA For. Serv. Gen. Tech. Rep. RM-43, Rocky Mt. For. an~ Range Exp. Stn., Fort Collins, CO. Johnsgard, Paul A. 1979. Birds of the Great Plains - Breeding Species and their Distribution. 546 p. Univ. of Nebr. Press, Lincoln and London. Johnson, R. Roy. 1972. The effects of "civilization" on the avifauna of the Salt River Valley. J. Ariz. Acad. Sci. (Proc. Suppl.: Abstr.) p.l9. Johnson, R. Roy, Lois T. Haight, and James M. Simpson. 1977. Endangered species vs. endangered habitats: a concept. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 68-79. USDA For. Serv. Gen. Tech. Rep. RM-43, Rocky Mt. For. and Range Exp. Stn., Fort Collins, Colorado. Johnson, R. Roy, and Dale Jones. 1977. Proc. Symposium on importance, preservation, and management of riparian habitat. USDA For. Serv. Gen. Tech. Rep. RM-43., Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO. 217 p. Johnston, Richard F. 1964. The breeding birds of Kansas. Univ. of Kansas Publ. Mus. Nat. Hist. 12(14): 575-655. Kindschy, Robert R. 1978. Rangeland management practices and bird habitat values. In Proc. Workshop on nongame bird habitat management in the coniferous forests of the western United States. p. 66-69. USDA For. Serv. Gen. Tech. Rep. PNW-64, Pac. Northwest For. and Range Exp. Stn., Portland, Oregon. Kochenderfer, J. N. 1970. Erosion control on logging roads in the Appalachians. USDA For. Serv. Res. Paper NE-158. Northeast For. Exp. Stn., Upper Darby, PA. Kochman, Eddie. 1979. Channelization in Colorado - past, present, and future. In Proc. The Mitigation Symposium. p. 586-589. USDA For. Serv. Gen. Tech.-aep. RM-65, Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO.

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431 K~chler, A. W. 1964. Potential natural vegetation of the conterminous United States. American Geographical Society Spec. Publ. no. 36. Wash., D.C.: Am. Geogr. Soc. Mathews, Bob. 1980. The Missouri, caged river. Kansas Fish and Game 37(1):20-27. McCormick, J. F. 1978. An initiative for preservation and management of a wetland habitat. USFWS, Wash., D.C. 20 p. Mustard, Eddie. 1978. Lowland river and stream habitat in Colorado - a pictorial view. In Lowland river and stream habitat in Colorado: a symposium. p. 4-10. Colo. Chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Pase, Charles P., and Earle F. Layser. 1977. Classification of riparian habitat in the Southwest. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 5-9. USDA For. Serv. Gen. Tech. Rep. RM-43, Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO. Peterson, Roger T. 1947. A field guide to the birds. Houghton Mifflin, Boston. Ports, Mark A. 1979. Occurrence and density studies of nongame wildlife in southwestern Kansas. Kansas Fish and Game Commission report. 55 p. Rising, James D. 1974. The status and faunal affinities of the summer birds of western Kansas. Univ. of Kansas Sci. Bull. 50:347-388. Robbins, Chandlers., Bertel Bruun, and Herbert S. Zim. 1966. Birds of North America. Golden Press, New York. 340 p. Sands, Anne, and Greg Howe. 1977. An overview of riparian forests in California: their ecology and conser vation. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 98-115. USDA For. Serv. Gen. Tech. Rep. RM-43, Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO. Sawyer, Nancy, and David Sawyer. 1979. Rural cottonwood-willow riverbottom and cattail marsh. Am. Birds 33(1):28. Schrupp, Donald L. 1978. The Wildlife values of lowland river and stream habitat as related to other habitats in Colorado. In Lowland river and stream habitat in Colorado: a symposium. p. 42-51. Colo. Chap. Wildl. Soc. and Colo. Audubon Council, Greeley, CO. Scott, Virgil E., Keith E. Evans, David R. Patton, and Charles P. Stone. 1977. Cavity-nesting birds of North American Forests. USDA For. Serv. Ag. Hand book No. 511, 112 p. Sibley, C. G. and L. L. Short, Jr. 1959. Hybridization in the buntings (Passerina) of the Great Plains. Auk. 76: 443-463. Stauffer, Dean F., and Louis B. Best. 1980. Habitat selection by birds of riparian communities: evaluating effects of habitat alterations. J. Wildl. Manage. 44{1):1-15. Stevens, Laurence, Bryan T. Brown, James M. Simpson, and R. Roy Johnson. 1977. The importance of riparian habitat to migrating birds. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 156-164. USDA For. Serv. Gen. Tech. Rep. ~43, Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO. Stevens, H. A. 1980. The Great Blue Heron in Kansas. Report to Kansas Fish and Game Commission.

432 USDA Forest Service. 1978. Proc. Symposium, Strategies for protection and management of floodplain wetlands and other riparian ecosystems. USDA For. Serv. Gen. Tech. Rep. W0-12, Wash., D.C., 410 p. Von Haartman, Lars. 1968. The evolution of resident versus migratory habitats in birds: some considerations. Ornis Fenn. 45(1):1-7. Wauer, Roland H. 1977. Significance of Rio Grande riparian systems upon the avifauna. In Proc. Symposium on importance, preservation, and management of riparian habitat. p. 165-174. USDA For. Serv. Gen. Tech. Rep. RM-43, Rocky Mt. For. and Range Exp. Stn., Fort Collins, CO. West, D. A. 1962. Hybridization in grosbeaks (Pheucticus) of the Great Plains. Auk 79:399- 424. Zimmerman, John L. 1979. Ten year summary of the Kansas breeding-bird survey: trends. Kan. Orn. Bull. 30(2):17-19.

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