Old Liviiii; Resources — The Great Plains 



299 



Table 1. Dislribution of species observed on 128 random- 

 ly selected quarter-sections in North Dakota in 1967. 1992, 

 and 1993 by breeding habitat and migratory strategy. 



Breeding habitat 



Permanent Sliort-distance Long-distance 



migrant 



migrant 



Total 



accounting for about 80% of the total number of 

 indicated pairs in eacii year. 



Of liie total number of breeding pairs of the 

 50 most common specie.s in the 3 years (Table 

 2). the five most commonly encountered 

 species, in order of abundance, were horned 

 lark (Ereniophila alpe.stris). chestnut-collared 

 longspur (Ccilcarius ornatiis). red-winged 

 blackbird {Agelaius phoeniceus). western 

 meadowlark (Stiiniella neglecta). and brown- 

 headed cowbird {Mohnlinis atcr). The homed 

 lark, the most common breeding bird species 

 recorded each year, is a species that is most 

 characteristic of cropland or heavily grazed 

 prairie and which favors open areas with low 

 sparse vegetation (.Stewart 1975). The overall 

 frequency and abundance of the brown-headed 

 cowbird are of concern because this brood par- 

 asite has been implicated in the decline of some 

 Neotropical migrants. 



Ninety percent of the 160 species observed 

 in the 3 years are migrants (Table 1 ). Moreover, 

 migrants constitute over 95% of the indicated 

 pairs detected in the sample units in each year. 

 The remaining (10%) species are year-round 

 residents in North Dakota. Of the species that 

 migrate, 82 (51%) are short-distance migrants 

 and 62 (39%) are long-distance (Neotropical) 

 migrants. 



The data indicate that breeding bird popula- 

 tions show considerable short- and long-term 

 variability. The patterns of population change 

 for many grassland and wetland species are 

 remarkably similar and consistent among taxo- 

 nomic groups (e.g., mallard [Anas platyrhyn- 

 chos] versus American coot [Fiilica americana] 

 versus savannah spanow [Passercithis sand- 

 wichensis]) and migration strategies (long-dis- 

 tance versus short-distance migrant; Tables 2 

 and 3). A common feature of these species is 

 their dependence on grassland and wetland 

 habitats on the breeding grounds; most breed in 

 the northern Great Plains but winter elsewhere. 

 Severe drought conditions in the Great Plains 

 may have played a major role in the depressed 

 populations (Tables 2 and 3) of some wetland 

 and grassland species in 1992 (an extremely dry 

 year) compared with 1967 (a near-average year) 

 and 1993 (an extremely wet year). 



Several species associated with grassland 

 and wetland habitats (e.g.. savannah spanow 

 and American coot) were relatively common in 

 1967, showed major declines in 1992, and 

 recovered slightly in 1993 (Table 2). The fact 

 that populations of some species (e.g., black 

 tern [Clilidonias iiiger]. Wilson's phalarope 

 \Pludan>pus tricolor]) remain below their 1967 

 levels suggests that precipitation alone may not 

 explain all of the changes in the populations of 

 grassland and wetland species. Drainage of wet- 

 lands, agriculture encroachment, and increased 

 fragmentation of native prairie are also suspect- 

 ed in the declines of some wetland and grass- 

 land species. 



Table 2. Nimiber of indicated 

 pairs of the 50 most common bird 

 species observed on 1 28 randomly 

 selected quarter-sections in North 

 Dal<ota in 1967, 1992. and 199.3. 



Species 



Migration 

 strategy' 



Breeding 

 habitat" 



Horned lark {Eremophiia alpestris) 



Chestnut-collared longspur {Calcarius ornalus) 



Red-winged blackbird {Agelaius phoeniceus] 



Western meadowlark {Slurnella neglecta) 



Brown-tieaded cowbird {Mololhrus alei) 



Lark bunting (Calamospiza melanocorys) 



Grasshopper sparrow {Ammodramus savannarum) 



Mourning dove (Zenaida macroura) 



Savannah sparrow (Passerculus sandwichensis) 



Clay-colored sparrow (Spizella pallida) 



Vesper sparrow (Pooecetes gramineus) 



Common grackle (Quiscalus quiscula) 



Eastern kingbird [Tyrannus tyrannus) 



Clifl swallow (Hirundo pyrrhonota) 



American cool {Fulica americana) 



Bobolink (Dolichonyx oryzivorus) 



Blue-winged teal (,4nas discors) 



Mallard (Anas platyrhynchos) 



House wren ( Troglodytes aedon) 



Barn swallow (Hirundo rustica) 



Western kingbird [Tyrannus verticalis) 



House sparrow (Passer domestical 



Yellow-headed blackbird (Xanlhocephalus xanthocephalus) 



Common yellowthroat (Geothlypis trichas) 



American goldfinch {Carduelis tristis) 



Baird's sparrow (Ammodramus bairdii) 



Killdeer (Charadrius vocilerus) 



Gadwall (Anas strepera) 



Marsh wren (Cistolhorus palustris) 



American robin ( Turdus migratorius) 



Yellow warbler (Dendroica petechia) 



Rufous-slded lowhee (Pipilo erythrophthalmus) 



Song sparrow (Melospiza melodia) 



Upland sandpiper (Bartramia longicauda) 



Northern pintail (Anas acuta) 



Bank swallow (Riparia riparia) 



Brown thrasher ( Toxosloma rufum) 



Black tern (Chlidonias nigei) 



Cedar waxwing (Bombycilla cedrorum) 



Field sparrow (Spizella pusilla) 



Northern shoveler (Anas clypeala) 



Franklin's gull (Larus pipixcan) 



Least llycalcher (Empidonax minimus) 



Brewer's blackbird (Euphagus cyanocephalus) 



Sora (Porzana Carolina) 



Chipping sparrow (Spizella passerina) 



Wilson's phalarope (Phataropus tricola) 



Lark sparrow (Chondestes grammacus) 



Gray catbird (Dumetella carolinensis) 



Ruddy duck (Oxyura jamaicensis) 



'SDM— short-distance migrant; LDM— long-distance migrant; RES— resident, 



"G/0— grassland-open habilat; WET— wetland-wet meadow; W/E— woodland-woodland-edge; SHR— shrubland; 0/T- 

 open habitat with trees. GEN— residential-habitat generalist. 



