BREEDING BIRD ABUNDANCE AND HABITAT ALONG THE DES LACS RIVER VALLEY, NORTH DAKOTA
ROBERT K. MURPHY, U.S. Fish and Wildlife Service, Des Lacs National Wildlife Refuge Complex, 8315 Hwy 8, Kenmare, ND 58746 ([email protected]) and MARRIAH L. SONDREAL, College of Natural Resources, University of Wisconsin, Stevens Point, WI 54481 (current address: N8386 County Highway D, Belleville, WI 53508)
The Des Lacs River originates in se changed markedly since. Woodlands Saskatchewan and extends 100 km into nw developed after extirpation of bison in the North Dakota before joining the Souris River region during the 1870s and, especially, after about 15 km nw of Minot (Figure 1). In the many decades of fire suppression following late 1800s, just before settlement along the settlement.4’7 The prairie was converted to river by peoples of European descent, the annually tilled croplands, except for a 0.5- valley of the “Riviere de Lacs” was mixed- to 2-km wide band of prairie which still exists grass prairie.7 In 1878, Elliot Coues described along the river. Nearly half of this extant the makeup of breeding birds along the prairie lies within the boundaries of Des Lacs Saskatchewan-North Dakota border,5 National Wildlife Refuge (DLNWR), which including the Des Lacs and Souris rivers. Bird encompasses the river valley just south of habitat along the Des Lacs River valley has the Saskatchewan-North Dakota border
Figure 1. Location of Des Lacs National Wildlife Refuge along the Des Lacs River valley in nw North Dakota.
82 Blue Jay Figure 2. The Des Lacs River valley in late summer, south of the Saskatchewan-North Dakota border.
61 (2). June 2003 83 (Figures 1 and 2). The refuge presents an edge (roughly 1500 ha): east- to north-facing opportunity for preserving native prairie and slopes along the valley and parts of adjacent its associated bird life. No quantified Drift Plain, variably (5-50%) wooded with description of contemporary breeding birds trees and tall shrubs, mostly Green Ash and and their habitat associations exists for this Chokecherry (Prunus virginiana)', (3) prairie major river valley, however. Our objective slope (roughly 750 ha): south- to west-facing was to fill this information gap and help slopes of the river valley, generally consisting identify local opportunities and limitations of native prairie dominated by grasses and for meeting habitat needs of bird species of forbs especially needlegrasses (Stipa spp.), regional and international conservation wheatgrasses (Agropyron spp.), Sideoats concern. Grama (Bouteloua curtipendula), Little Bluestem (Schizachyrium scoparium), Big Study Area and methods Bluestem (Andropogon gerardii), and DLNWR encompasses the Des Lacs River members of the legume and aster families; valley in Burke and Ward counties in nw (4) drift prairie (roughly 2250 ha): level to North Dakota, stretching south 42 km from rolling (<5°) native prairie on the Drift Plain, se Saskatchewan. The valley of the Des Lacs dominated by a mix of Smooth Brome River was created when glacial meltwater (Bromus inermis), Kentucky Bluegrass (Poa cut through a vast regional ground moraine pratensis), Western Snowberry known as the Drift Plain.3 Today the upland (Symphoricarpos occidentalis), and topography changes from the gently rolling Silverberry (Elaeagnus commutata); (5) Drift Plain to steep (> 1 5 °) slopes that dense nesting cover (752 ha): cultivated tracts descend 15 to 80 m to the river (elevation of Drift Plain that have been seeded to a about 544 m). The slopes are interrupted by mixture of introduced species of grasses and wooded draws and coulees, which have forbs to provide nesting cover mainly for intermittent streams that drain the adjacent ducks. Drift Plain. The narrow (1 -3 km wide), 7913- ha riverine refuge includes about 2025 ha of We used point counts8 to survey breeding impounded open water and 280 ha of marsh birds throughout uplands at DLNWR from and wet meadow bordered by roughly 5600 the end of May through June in 1994 and ha of upland habitats. Upland soils are 2001. We used 30-m radius point count plots mostly well-drained, level to steep loams in woodland, and 75-m radius plots in other formed in glacial till. The area climate is more open, habitats. Plots for woodland, continental, with short summers and long prairie slope, and prairie-woodland edge were cold winters; annual precipitation averages along 300- to 1000-m long transects that 45 cm (U.S. Fish and Wildlife Service [FWS], followed the mid-slope between the Drift unpubl. refuge data). Our survey in 1994 Plain (above) and the river or bottoms of followed a series of relatively dry years adjoining coulees (below). Plots on the Drift (1988-1993, average annual precipitation = Plain were on transects that crossed through 35 cm), and the survey in 2001 occurred the approximate center of representative after many wet years (1994-2000, average dense nesting cover and drift prairie habitats. annual precipitation = 51 cm). We typically randomized our starting point on each transect and then spaced plot centers We identified five major upland habitats at least 200 m apart by pacing. We conducted on the refuge: (1) woodland (351 ha): east- surveys in 2001 in most of the same general to north-facing slopes along the valley and areas used in 1994, although we seldom used adjacent coulee bottoms, with more than any one plot in both years. Habitat of each 50% tree canopy cover, primarily Green Ash plot was classified in the field as woodland, (Fraxinuspennsylvanica) and American Elm woodland-prairie edge, prairie slope, drift (Ulmus americcma); (2) woodland-prairie prairie, or dense nesting cover based on the
84 Blue Jay dominant vegetation, slope, and aspect. We of seasonally flooded wetlands in the Drift surveyed birds across all major upland Plain such as Wilson’s Snipe and Wilson’s habitats regardless of management history Phalarope; seven species of upland-nesting (for example, some areas had been prescribe- ducks; four swallow species that foraged over burned the previous year, or were being prairie slope, drift prairie, and dense nesting grazed by livestock), although we excluded cover habitats but nested elsewhere; and dense nesting cover areas that were being several non-breeding late migrant or vagrant disked in preparation for reseeding. species such as Tennessee Warbler or Western Wood Pewee. We surveyed each plot once for eight minutes between 5:30 and 8:30 AM. We Occurrences of several common breeding occasionally surveyed birds until 9:00 AM species differed between our survey years on unusually calm mornings, and did not (Figure 3). Yellow Warbler occurred about conduct surveys during steady rain or strong twice as frequently on woodland plots in (>25 kmph) winds. Each plot was entered 2001 than in 1994. In woodland-prairie edge, slowly to note birds that might be disturbed Cedar Waxwing occurred twice as frequently by our approach. We recorded numbers of in 2001 as in 1994, but Eastern Kingbird and singing males of each species in each plot Song Sparrow were nearly twice as frequent and excluded non-singing birds from our in 1994. Savannah Sparrow and Bobolink summaries except for obvious breeding pairs occurred 50-80% more frequently in drift (e.g., a pair of adult sparrows carrying food prairie and dense nesting cover in 2001 than and eliciting threat notes). For species that in 1994, and Savannah Sparrow also was use aerial displays to attract mates and more frequent in prairie slope in 2001. Clay- defend territories (e.g., Sprague’s Pipit), we colored Sparrow occurred 20-100% more recorded a singing individual if its flight path frequently in all habitats in 2001 compared crossed over the plot during our survey. to 1994. Birds detected outside each plot but within the same respective habitat type also were The greatest number of species occurred recorded to help us build a list of infrequently in woodland-prairie edge and the fewest encountered species.8 We generally occurred in dense nesting cover (Table 1). considered a singing male to indicate a Woodland-prairie edge also had the greatest breeding pair, but calculated the abundance number of common species, 14, compared of Brown-headed Cowbird and Cedar to five to eight common species in other Waxwing at each point by dividing the total habitats (Figure 3). However, most species number observed by two.12 For every that were common in woodland-prairie edge species we calculated the average number of also were common in other habitats. indicated pairs per point count plot in each habitat class for 1994 and 2001. We also Woodland Species plotted the percentage frequency of Least Flycatcher, House Wren, and occurrence for common species (i.e., those Yellow Warbler were the most abundant with an average abundance of more than 0.1 species in woodlands (Table 1). These species indicated pairs/plot in at least one year), to also were quite common in the woodland- look for large differences in species prairie edge, especially Yellow Warbler. Less occurrence between study years. common were Veery and Ovenbird, which occupied the most mature woodland stands Results in deep, broad coulees and along some east¬ We recorded 72 species of breeding birds facing slopes. Red-Eyed Vireo was most (475 and 247 plots surveyed in 1994 and frequently found in such places, but occurred 2001, respectively; Table 1). This total occasionally in woodland-prairie edge. Gray excludes shorebirds that nested in margins Catbird, Cedar Waxwing, and Spotted
61 (2). June 2003 85 Towhee generally occurred near edges of prescribe-bumed drift prairie. Dense nesting relatively young woodland stands, usually cover was important habitat for Sedge Wren in understory shrub especially Chokecherry. and Le Conte’s Sparrow (Table 1).
Woodland-Prairie Edge Species Discussion Woodland-prairie edge was the most We found that contemporary upland important habitat of Willow Flycatcher, Song habitats at DLNWR support a varied Sparrow, and Brown-headed Cowbird (Table breeding bird community: 72 upland breeding 1). Because many of our detections of species, with 5 to 14 species common in Brown-headed Cowbird consisted of single each of five major upland habitats. The total adults of either sex, the species’ abundance number of breeding bird species on the refuge in edge and open habitats seemed better may be nearly twice as great, however, when reflected by its frequency of occurrence: we considering rare to occasional species in detected cowbirds on about 40% of survey uplands in addition to those closely plots on the woodland-prairie edge (Figure associated with buildings on and adjacent to 3), compared with only 3-18% of plots in the refuge (e.g., House Sparrow, Barn more open habitats. Song Sparrow typically Swallow), plus many species of grebes, terns, occupied edge habitat at the bottom of slopes, ducks, rails, and other waterbirds that breed near water. Willow Flycatcher occurred in the marshes and open water mainly in extensive tall shrub up to the mid¬ impoundments. Although a list of bird slope. species specific to DLNWR has not been compiled since the 1960s, a collective list of Grassland Species birds species occurring on DLNWR and Clay-colored Sparrow was the only species nearby Upper Souris and J. Clark Salyer that was common in all upland habitats on National Wildlife Refuges indicates that 150 DLNWR; it was as abundant in woodland- species “nest regularly” on the three refuges.1 prairie edge, where tall shrub cover was extensive, as it was in drift prairie where tall Between-year Differences shrubs were less prevalent (Table 1, Figure Occurrences of several common bird 3). Other grassland bird species occurred in species differed between our 1994 and 2001 drift prairie, prairie slope, and dense nesting surveys. Increased occurrences of common cover habitats. Savannah Sparrow was grassland species - Clay-colored Sparrow, particularly ubiquitous in drift prairie and Savannah Sparrow, and Bobolink - likely were dense nesting cover and appeared to avoid associated with concurrent increases in local woodland edge. Bobolink was common in drift or regional populations. Average total numbers prairie and in dense nesting cover especially of these three species increased by 2- to 4- where hay had been harvested 1-3 years fold on Breeding Bird Survey routes within earlier. Vesper Sparrow and Grasshopper 100 km of DLNWR between 1994 and Sparrow were less common than Clay-colored 2001.14 These increases may be linked to and Savannah sparrows, preferring prairie increased growth of grassland vegetation from slope. Sprague’s Pipit occurred along several above-average annual precipitation during the upper prairie slopes and in drift prairie areas period 1994-2000. The attractiveness of that had been prescribe-bumed and grazed native prairie on DLNWR to grassland birds during the previous 4-5 years. Most also may have improved due to a general detections of the infrequently occurring Baird’s increase in the ratio of herbaceous to woody Sparrow also were in recently burned and vegetation as a result of prescribed bums, at grazed drift prairie. Western Meadowlark was least for Bobolink and perhaps Savannah recorded only occasionally, in drift prairie or Sparrow.12 Clay-colored Sparrow abundance dense nesting cover. Homed Lark and Killdeer typically declines following burning of occurred rarely, on recently (< 6 months) northern mixed-grass prairie.9,12
86 Blue Jay □ 1994
■ 2001
Ash-elm Woodland
100 s 80 | 60 | 40
*20 0 ..1 fkj.fi JkjL.u k IL* MODO WFL LEFL EAKI REVI HOWR GRGA CHOW YWAR SFTO CCSP SOSP BHCO AMGO
Woodland-prairie Edge
100 S 80 | 60 | 40
0®s 20 o GAKI GRGA YWAR CCSP VESP SAVS GRSP SOSP
Prairie Slope
CCSP SAVS GRSP LCSP BOBO
Drift Prairie
e o
o o o
SB/VR COYE CCSP SAVS GRSP LCSP BOBO
Dense Nesting Cover
Figure 3. Frequency of occurrence of common breeding bird species in major upland habitats at Des Lacs National Wildlife Refuge, 1994 (white bars) and 2001 (dark bars). Species include American Goldfinch (AMGO), Brown-headed Cowbird (BHCO), Bobolink (BOBO), Clay-colored Sparrow (CCSP), Cedar Waxwing (CEDW), Common Yellowthroat (COYE), Eastern Kingbird (EAKI), Gray Catbird (GRCA), Grasshopper Sparrow (GRSP), House Wren (HOWR), Le Conte's Sparrow (LCSP), Least Flycatcher (LEFL), Mourning Dove (MODO), Red-eyed Vireo (REVI), Savannah Sparrow (SAVS), Sedge Wren (SEWR), Song Sparrow (SOSP), Spotted Towhee (SPTO), Vesper Sparrow (VESP), Willow Flycatcher (WIFL), Yellow Warbler (YEWA).
61 (2). June 2003 87 Breeding birds and habitat: present and past passerines especially the endemic Baird’s Most woodland bird species and many Sparrow and Sprague’s Pipit.13 Increases in woodland-prairie edge bird species that we judicious use of prescribed burning and found probably were rare or absent as livestock grazing would provide more breeding species when trees were scarce in suitable habitat for these native species, the area a century ago,7 for example: while still providing habitat for more Cooper’s Hawk, Hairy Woodpecker, Least generalized grassland bird species such as Flycatcher, Red-Eyed Vireo, Veery, Savannah Sparrow and Clay-colored American Crow, and Baltimore Oriole. Sparrow.12 Regardless of vegetation Perhaps even Brown-headed Cowbird was conditions, some species such as Northern much less common in the area before Harrier may avoid narrow tracts of drift settlement; we found it to be less common prairie bordered by cropland, simply in open habitats compared to woodland- because they need broader grassland tracts;10 prairie edge. In addition, several introduced territories of the harrier may cover 100-200 species such as Ring-necked Pheasant now ha.2 Western Meadowlark has relatively occur. Thus, species diversity presumably large territories (5-10 ha) for a grassland is greater now than it was before the area passerine, but evidence of the species’ was settled by peoples of European descent sensitivity to habitat area is unclear in the in the late 1800s, and before establishment northern Great Plains.10 of the refuge in 1935. Implications for managing habitat In contrast, the diversity of grassland- Eleven grassland bird species that dependent bird species has diminished on occurred at DLNWR during or prior to our DLNWR. Although we found several survey are included in a 1995 FWS list of grassland bird species to be quite common “Nongame Birds of Management Concern” (Clay-colored Sparrow, Savannah Sparrow, (Table l).16 Only one woodland species and Bobolink), most were uncommon and (Veery) and none of the woodland-prairie some were absent. Killdeer, Horned Lark, edge species that we recorded at DLNWR Western Meadowlark, Sprague’s Pipit, and are on the list. Woodland-prairie edge is a Baird’s Sparrow are among breeding species widespread habitat type on the refuge that, considered characteristic of the area’s mixed- in the absence of fire, would continue to grass prairie,5,15 but they occur infrequently replace drift prairie and some prairie slope. on DLNWR. Chestnut-collared Longspur, The only grassland bird species that were another characteristic species, was not common in this habitat were Clay-Colored detected on DLNWR although we observed Sparrow and Brown-headed Cowbird. it defending breeding territories on adjacent, Woodland bird species that were common in privately owned tracts of grazed prairie. the woodland-prairie edge - Least Flycatcher, Burrowing Owl and Ferruginous Hawk also House Wren, and Yellow Warbler - are are characteristic, but were not observed widespread in North America and have stable during our study and have not been recorded to increasing populations.14 Conversion of on DLNWR for decades. The community of woodland-prairie edge habitat to drift prairie grassland bird species that are uncommon to at DLNWR, through repeated prescribed fire, absent on DLNWR generally requires would negligibly influence continental shorter, sparser, more herbaceous prairie population trends of woodland bird species vegetation than that available on the refuge while clearly benefitting populations of today.11 Replacement of native grasses by grassland bird species, which generally are introduced species, especially Smooth declining. Conversely, mature ash-elm Brome, also reduces the attractiveness of the woodland at DLNWR typically occurs in mixed-grass prairie for several native steep, fire-sheltered areas that may be
88 Blue Jay overwhelmingly difficult to restore to prairie. who contributed greatly to the knowledge Such areas probably would continue to and appreciation of birdlife in northwestern provide modest habitat for area-sensitive, North Dakota. Beth Madden provided sound “forest interior” species such as Veery and advice on our survey methods. Sharon Ovenbird without hindering widespread Anderson and Natalie Fahler helped improvement in grassland bird habitat.6 summarize data. We thank Steve Davis, Todd Grant, Ron Martin, Cory Rubin, Dan Dense nesting cover was planted on Severson, and Karen Smith for helpful DLNWR mainly to provide nesting cover discussions and comments surrounding this for upland-nesting ducks, but we found that paper. it also increased grassland bird diversity on the refuge by providing important habitat 1. BERKEY, G, and R. MARTIN. 2001. for Sedge Wren and Le Conte’s Sparrow. We National Wildlife Refuges along the Souris also detected several Nelson’s Sharp-tailed River Loop: bird list. U.S. Fish and Wildlife Sparrows in dense nesting cover. These three Service: Des Lacs, J. Clark, and Upper Souris species typically are associated with wetland National Wildlife Refuges, North Dakota. margins in the northern plains region, but the rank, coarse cover of introduced grass- 2. BILDSTEIN, K. L, and J. B. GOLLOP. forb stands apparently emulates the native 1988. Northern Harrier Circus cyaneus. In: wet meadow vegetation that attracts these Palmer, R. S. (ed.). The Birds of North species.11 We also often observed Northern America, Vol. 4. Yale University Press, New Harriers and Short-eared Owls foraging in Haven, Connecticut, p. 251-303. dense nesting cover; nesting by these species has been noted in dense nesting cover at 3. BLUEMLE, J. P. 1991. The face of North DLNWR (FWS, unpubl. data). Dakota. North Dakota Geological Survey Educational Series 21. Conclusions We documented a varied upland breeding 4. CAMPBELL, C., I. D. CAMPBELL, C. bird community at DLNWR, but one in which B. BLYTH, and J. H. MCANDREWS. 1994. native grassland bird diversity has declined. Bison extirpation may have caused aspen Conservation needs of these grassland bird expansion in western Canada. Ecography species are urgent. The total area available 17:360-362. on many of the refuge’s drift prairie tracts may be inadequate for some species. Suitable 5. COUES, E. 1878. Field notes on birds habitat could be made widely available for observed in Dakota and Montana along the other grassland bird species, however, with forty-ninth parallel during the seasons of moderately aggressive land management, 1873 and 1874. U.S. Geological and especially expanded use of a combined fire Geographic Survey Territorial Bulletin 4:545- and grazing regime that was beginning to 661. develop at DLNWR during our study. Efforts to improve grassland bird habitat on 6. GRANT, T. A., and G.B. BERKEY. 1999. the refuge coincide with restoration goals for Forest area and avian diversity in fragmented native prairie flora, as might be the case in aspen woodland of North Dakota. Wildlife other prairie river valleys of the northern Society Bulletin 27:904-914. plains region. 7. GRANT, T. A., R. K. MURPHY, R. Acknowledgments DIEBOLL, and C. RUBIN, ms In Review. We dedicate this paper to the memory of Increases in woody cover on prairie refuges Bob and Ann Gammell, amateur naturalists in North Dakota.
61 (2). June 2003 89 90
Table 1. Relative abundance of breeding bird species in major upland habitats of Des Lacs National Wildlife Refuge, nw North Dakota, denoted by the average number of detections of indicated pairs per 8-minute point count survey on 30-m radius plots in ash-elm woodland and on 75-m radius plots in other habitats. “X” indicates 0.01-0.05 detections per point count survey. *G o < T3 73 oo £ ^ X X XXX X X X X X X X X 0 X o Black-billed Cuckoo s X Great Homed Owl X 61 (2). June 2003 91 92 Blue Jay 61 (2). June2003 T—H O X Baird’s Sparrow* X CO o o RURAL BANDERS IN THE YORKTON AREA* C. STUART HOUSTON, 863 University Drive, Saskatoon, SK S7N 0J8 Of the six early banders active within the Bard, of the Saskatchewan Natural History Yorkton - Duck Mountain (YDM) bird area, Museum, released 11 banded magpies and Judge J.A.M. Patrick, who banded from 1929 13 crows as part of his crow and magpie to 1933, was the first.2 In 1937, Bill and campaign.3 R. Lome Scott banded 19 Great Lindsay Wotherspoon banded 885 birds of Homed Owls, 19 Red-tailed Hawks, 6 Black¬ 42 species, with 12 recoveries, in the village billed Magpies, 756 Tree Swallows and 425 of Hyas and on their farm on the north side Mountain Bluebirds along his bird box trail of that village.1 Three “outside” banders on Highway 35, within the western boundary visited the YDM area in the 1940s: Fred of the YDM area.4 J.A. Briggs of Regina 94 Blue Jay