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Breeding Bird Survey: Population Trends 1966-92


by
Bruce G. Peterjohn
National Biological Service
John R. Sauer
National Biological Service
Sandra Orsillo
National Biological Service
The North American Breeding Bird Survey (BBS) was begun in 1966 to collect standardized data on bird populations along more than 3,400 survey routes across the continental United States and southern Canada. The BBS has been used to document distributions and establish continental, regional, and local population trends for more than 250 species.
We summarize here survey-wide patterns in the 1966-92 population trend estimates for 245 species of birds observed on a minimum of 40 routes with a mean relative abundance of 1.0 bird per route. Survey-wide trend estimates are also summarized for six groupings of birds, providing insight into broad geographical patterns of population trends of North American birds.
Methods
The BBS routes are located along secondary roads and surveyed each year during the peak of the breeding season by observers competent in bird identification. Each route is 39.4 km (24.5 mi) long, with 50 stops placed at 0.8-km (0.5-mi) intervals (Robbins et al. 1986). To estimate population change, we used a procedure called route regression, described in greater detail by Geissler and Sauer (1990).
We examined population change in several ways. First, we estimated overall population change for individual species over the entire survey area. Second, we looked for temporal and geographic patterns in individual bird species (e.g., Sauer and Droege 1990).
Additionally, we analyzed overall patterns of population change for several species of particular management interest. Groups of birds were defined by migration status (nonmigratory, short-distance, and Neotropical migrants) or by breeding habitat (grassland, shrubland, or woodland; see also Peterjohn and Sauer 1993). For each group, we determined the percentage of species with positive (> 0) trends. If population change is not consistent within the group, about half (50%) of the species should show positive trends. Clearly, some species will show very significant declines (or increases) over the interval, and these species can be identified in the Appendix. However, the percentage of species with positive population trends is a convenient summary of information from all species within the group to demonstrate overall trend patterns.
Finally, to display regional patterns of population change, we calculated the mean trend for the species in each group for each survey route. We used an Arc/Info geographic information system to summarize and display geographic patterns of population change (Isaaks and Srivastava 1989; ESRI 1992).
Trends
Of the 245 species considered, 130 have negative trend estimates, 57 of which exhibit significant declines. Species with negative trend estimates are found in all families, but they are especially prevalent among the mimids (mockingbirds and thrashers) and sparrows. A total of 115 species exhibits positive trends, 44 of which are significant increases. Flycatchers and warblers have the largest proportions of species with increasing populations.
Fig. 1. Geographic patterns in the mean trends for grassland bird species during 1966-92.
The percentage of increasing species within each group of species having shared life-history traits is summarized in the Table. The most consistent declines are by grassland birds; only 18% have increasing population trends. These declines are most widespread in eastern North America, where few grassland species breed (Fig. 1). Declining populations are also prevalent across the Great Plains, which includes the breeding ranges of most grassland birds. The pattern within western North America is mixed, except for regions of declines along the Pacific coast.
Fig. 2. Geographic patterns in the mean trends for shrubland and old-field bird species during 1966-92.
A significant proportion of shrubland and old-field bird species also exhibits population declines (Table). As with grassland birds, regions with declines are most prevalent in eastern North America as well as in the southern Great Plains from Kansas and Missouri south to Texas (Fig. 2). Shrubland species appear to be generally increasing in western North America.
Fig. 3. Geographic patterns in the mean trends for woodland bird species during 1966-92.
A majority of woodland bird populations is increasing across most of the continent (Fig. 3). Decreasing populations prevail in a few regions, such as along the Appalachians from West Virginia to northern Alabama, from Arkansas across central Texas, and along the Pacific coast from Oregon to central California. Woodland birds, however, are increasing in more areas than either grassland or early successional species.
Table. Percentage of species with increasing populations for six groups of birds having shared life-history traits. The P value indicates the probability that the percentage differs from 50%.  
Group No. of species
in each group		 Increasing
(%)		 P
Breeding habitats      
Grassland 17 18 0.01
Shrubland 58 34 0.02
Woodland 80 59 0.15
Migration      
Short distance 69 42 0.23
Nonmigratory 41 41 0.35
Neotropical 98 50 0.92
All species 237 47 0.36

Fig. 4. Geographic patterns in the mean trends for Neotropical migrant bird species during 1966-92.
Neotropical migrants have received considerable attention in recent years, yet as many species have increased as have decreased during 1966-92 (Table). A region with apparently declining populations extends from the southern Great Plains across the southeastern states and along the Appalachian Mountains to southern New England (Fig. 4). Increasing mean populations prevail across the northern Great Plains and throughout much of western North America. The pattern of population decline in the eastern United States noted by Robbins et al. (1989) occurred after 1978 and is not reflected in these long-term trends.
Fig. 5. Geographic patterns in the mean trends for short-distance migrant bird species during 1966-92.
Short-distance migrants and permanent residents have slightly greater percentages of decreasing species (Table). Both groups have negative mean trends in the southeastern states and from the lower Great Lakes into the Appalachian Mountains, but the patterns elsewhere are mixed (Figs. 5, 6).
Fig. 6. Geographic patterns in the mean trends for permanent resident bird species during 1966-92.
These results indicate that grassland and shrubland birds are experiencing the most consistent and widespread declines of any group of species. Whenever possible, appropriate conservation measures should be undertaken to enhance the population trends of these species. While the BBS data indicate the population trends for breeding birds, these data are not designed to identify the factors responsible for these trends. To understand how bird populations are responding to the changing habitat conditions in North America, additional studies are needed that would combine the BBS results with regional data on land-use changes, weather conditions, and other variables.
Appendix. Population trends of birds from the North American Breeding Bird Survey. To appear in this list, the species must have been seen on > 40 routes at an average count of > 1 bird/route. We present trends (%/year), probability (P), and the number of routes on which the species was seen. See Peterjohn and Sauer 1993 for group classification.
Species Scientific name Trend P * No. of routes      Species Scientific name Trend P * No. of routes
American white pelican Pelecanus erythrorhynchos 3.60 0.00 152   Sandhill crane Grus canadensis 4.30 0.00 259
Great egret Casmerodius albus 1.5 ns 513   Killdeer Charadrius vociferus -0.38 ns 2,692
Little blue heron Egretta caerulea -1.45 ns 429   Black-necked stilt Himantopus mexicanus 0.63 ns 119
Cattle egret Bubulcus ibis 2.09 ns 475   Willet Catoptrophorus semipalmatus -0.72 ns 295
White ibis Eudocimus albus 3.17 ns 173   Upland sandpiper Bartramia longicauda 3.28 0.00 687
White-faced ibis Plegadis chihi 32.27 0.01 61   Long-billed curlew Numenius americanus -1.61 ns 234
Canada goose Branta canadensis 7.05 0.00 1,090   Marbled godwit Limosa fedoa 0.71 ns 188
Mottled duck Anas fulvigula -5.27 0.03 64   Common snipe Gallinago gallinago 0.14 ns 1,011
Mallard A. platyrhynchos 0.98 ns 1,890   Laughing gull Larus atricilla 6.01 0.00 125
Northern pintail A. acuta -5.65 0.00 502   Franklin's gull L. pipixcan -5.95 ns 231
Blue-winged teal A. discors -0.92 ns 814   Ring-billed gull L. delawarensis 7.43 0.02 684
Northern shoveler A. clypeata 0.18 ns 379   California gull L. californicus -1.27 ns 230
Gadwall A. strepera 3.76 0.00 389   Herring gull L. argentatus -2.06 0.09 474
Lesser scaup Aythya affinis 2.08 ns 263   Glaucous-winged gull L. glaucescens 3.85 0.09 40
Red-breasted merganser Mergus serrator -9.57 0.02 53   Great black-backed gull L. marinus -1.47 ns 125
Black vulture Coragyps atratus 1.72 ns 540   Black tern Chlidonias niger -4.51 0.00 368
Turkey vulture Cathartes aura 0.37 ns 1,691   Rock dove Columba livia 1.04 0.06 2,255
Ring-necked pheasant Phasianus colchicus -1.24 0.10 1,263   Band-tailed pigeon C. fasciata -3.69 0.00 189
Northern bobwhite Colinus virginianus -2.43 0.00 1,338   White-winged dove Zenaida asiatica 0.03 ns 78
Scaled quail Callipepla squamata -3.31 0.00 104   Mourning dove Z. macroura 0.02 ns 2,726
Gambel's quail C. gambelii 0.90 ns 82   Common ground dove Columbina passerina -3.13 0.01 194
California quail C. californica -0.04 ns 264   Yellow-billed cuckoo Coccyzus americanus -1.30 0.00 1,637
Mountain quail Oreortyx pictus 1.37 ns 112   Lesser nighthawk Chordeiles acutipennis 5.08 0.03 118
American coot Fulica americana -0.51 ns 620   Common nighthawk C. minor -0.34 ns 1,609
Chuck-will's-widow Caprimulgus carolinensis -0.78 ns 522   Blue-gray gnatcatcher Polioptila caerulea 1.03 ns 1,233
Black swift Cypseloides niger 1.61 ns 79   Black-tailed gnatcatcher P. melanura -0.22 ns 57
Chimney swift Chaetura pelagica -0.84 0.08 1,789   Eastern bluebird Sialia sialis 2.52 0.00 1,633
White-throated swift Aeronautes saxatalis -3.38 ns 189   Mountain bluebird S. currucoides 0.56 ns 422
Broad-tailed hummingbird Selasphorus platycercus 0.42 ns 115   Veery Catharus fuscescens -1.06 0.06 964
Rufous hummingbird S. rufus -3.38 0.00 188   Gray-cheeked thrush C. minimus -4.46 ns 43
Red-headed woodpecker Melanerpes erythrocephalus -1.84 0.00 1,236   Swainson's thrush C. ustulatus 0.00 ns 707
Acorn woodpecker M. formicivorus 0.98 ns 138   Hermit thrush C. guttatus 2.10 0.01 912
Golden-fronted woodpecker M. aurifrons -1.86 ns 56   Wood thrush Hylocichla mustelina -1.88 0.00 1,510
Red-bellied woodpecker M. carolinus 0.59 ns 1,246   American robin Turdus migratorius 1.03 0.01 2,588
Yellow-bellied sapsucker Sphyrapicus varius -0.85 ns 605   Varied thrush Ixoreus naevius 2.16 0.06 148
Nuttall's woodpecker Picoides nuttallii 1.44 ns 95   Wrentit Chamaea fasciata -1.39 ns 113
Downy woodpecker P. pubescens 0.14 ns 2,214   Gray catbird Dumetella carolinensis -0.42 ns 1,941
Yellow-shafted flicker Colaptes auratus -2.75 0.00 2,062   Northern mockingbird Mimus polyglottos -0.98 0.03 1,694
Red-shafted flicker C. cafer -0.87 ns 689   Sage thrasher Oreoscoptes montanus 1.16 ns 244
Olive-sided flycatcher Contopus borealis -2.52 0.00 736   Brown thrasher Toxostoma rufum -1.19 0.01 1,917
Western wood-pewee C. sordidulus -0.39 ns 637   Curve-billed thrasher T. curvirostre -3.59 0.00 100
Eastern wood-pewee C. virens -1.64 0.00 1,719   California thrasher T. redivivum -4.06 0.05 83
Yellow-bellied flycatcher Empidonax flaviventris 3.58 0.01 263   Sprague's pipit Anthus spragueii -3.52 0.02 140
Acadian flycatcher E. virescens 0.50 ns 854   Cedar waxwing Bombycilla cedrorum 2.36 0.00 1627
Alder flycatcher E. alnorum 1.30 0.04 788   Phainopepla Phainopepla nitens 2.53 0.05 104
Willow flycatcher E. traillii -0.62 ns 1,152   Loggerhead shrike Lanius ludovicianus -3.20 0.00 1364
Least flycatcher E. minimus -0.55 ns 1,150   European starling Sturnus vulgaris -0.99 0.02 2727
Hammond's flycatcher E. hammondii 1.50 ns 221   White-eyed vireo Vireo griseus -0.15 ns 945
Dusky flycatcher E. oberholseri 0.72 ns 265   Solitary vireo V. solitarius 3.28 0.00 954
Pacific-slope flycatcher E. difficilis 1.47 ns 218   Warbling vireo V. gilvus 1.31 0.01 1740
Eastern phoebe Sayornis phoebe 0.64 ns 1,650   Philadelphia vireo V. philadelphicus 1.50 ns 191
Ash-throated flycatcher Myiarchus cinerascens 2.38 0.01 370   Red-eyed vireo V. olivaceus 1.39 0.01 2020
Great crested flycatcher M. crinitus 0.03 ns 1,804   Tennessee warbler Vermivora peregrina 4.21 ns 341
Brown-crested flycatcher M. tyrannulus 6.15 0.00 47   Orange-crowned warbler V. celata -0.71 ns 346
Cassin's kingbird Tyrannus vociferans -1.74 ns 138   Nashville warbler V. ruficapilla 1.35 ns 673
Western kingbird T. verticalis 1.51 0.01 942   Northern parula Parula americana 0.82 ns 970
Eastern kingbird T. tyrannus -0.10 ns 2,267   Yellow warbler Dendroica petechia 0.94 0.05 2161
Scissor-tailed flycatcher T. forficatus -0.08 ns 244   Chestnut-sided warbler D. pensylvanica -0.60 ns 788
Horned lark Eremophila alpestris -0.65 ns 1,750   Magnolia warbler D. magnolia 2.80 0.00 527
Purple martin Progne subis 0.71 ns 1,623   Cape May warbler D. tigrina 2.95 ns 239
Tree swallow Tachycineta bicolor 1.27 0.04 1,707   Myrtle warbler D. coronata 1.41 0.09 575
Violet-green swallow T. thalassina 0.76 ns 511   Audubon's warbler D.c. auduboni 0.08 ns 386
Northern rough-winged swallow Stelgidopteryx serripennis 0.95 ns 2,119   Black-throated gray warbler D. nigrescens 2.32 0.07 190
Townsend's warbler D. townsendi 1.63 ns 145   Bank swallow Riparia riparia -0.48 ns 1,318
Hermit warbler D. occidentalis 0.79 ns 82   Cliff swallow Hirundo pyrrhonota 0.98 ns 1,737
Black-throated green warbler D. virens -0.45 ns 637   Barn swallow H. rustica 0.37 ns 2,701
Blackburnian warbler D. fusca 0.87 ns 511   Gray jay Perisoreus canadensis -1.28 ns 350
Pine warbler D. pinus 2.12 0.00 797   Steller's jay Cyanocitta stelleri 0.39 ns 328
Prairie warbler D. discolor -2.15 0.00 773   Blue jay C. cristata -1.81 0.00 1,986
Bay-breasted warbler D. castanea -0.04 ns 216   Scrub jay Aphelocoma coerulescens 1.27 0.04 272
Blackpoll warbler D. striata -0.33 ns 178   Pinyon jay Gymnorhinus cyanocephalus -1.65 ns 132
Black-and-white warbler Mniotilta varia 0.91 ns 1126   Black-billed magpie Pica pica -1.34 0.05 577
American redstart Setophaga ruticilla -0.58 ns 1299   American crow Corvus brachyrhynchos 0.85 0.06 2,578
Ovenbird Seiurus aurocapillus 0.55 ns 1278   Fish crow C. ossifragus 2.93 0.01 466
Northern waterthrush S. noveboracensis 0.49 ns 615   Chihuahuan raven C. cryptoleucus -2.48 ns 87
Kentucky warbler Oporornis formosus -0.77 ns 685   Common raven C. corax 3.66 0.00 1,202
Mourning warbler O. philadelphia 0.15 ns 538   Black-capped chickadee Parus atricapillus 1.89 0.00 1,433
MacGillivray's warbler O. tolmiei -0.58 ns 309   Carolina chickadee P. carolinensis -0.67 ns 862
Common yellowthroat Geothlypis trichas -0.48 ns 2361   Mountain chickadee P. gambeli 0.07 ns 291
Hooded warbler Wilsonia citrina 1.49 ns 608   Chestnut-backed chickadee P. rufescens -1.54 ns 133
Wilson's warbler W. pusilla 0.53 ns 525   Plain titmouse P. inornatus -2.30 0.01 180
Canada warbler W. canadensis -0.73 ns 504   Tufted titmouse P. bicolor 0.64 ns 1,289
Yellow-breasted chat Icteria virens -0.43 ns 1273   Black-crested titmouse P.b. atricristatus 2.06 0.03 64
Summer tanager Piranga rubra -0.19 ns 761   Verdin Auriparus flavicep -1.38 ns 97
Scarlet tanager P. olivacea 0.22 ns 1257   Bushtit Psaltriparus minimus -1.13 ns 250
Western tanager P. ludoviciana -0.31 ns 472   Red-breasted nuthatch Sitta canadensis 2.48 0.00 872
Northern cardinal Cardinalis cardinalis -0.21 ns 1591   Brown-headed nuthatch S. pusilla -1.30 ns 290
Pyrrhuloxia C. sinuatus -0.73 ns 61   Cactus wren Campylorhynchus brunneicapillus -0.89 ns 136
Rose-breasted grosbeak Pheucticus ludovicianus -0.19 ns 1146   Black-headed grosbeak P. melanocephalus -0.32 ns 509
Rock wren Salpinctes obsoletus -1.68 0.04 509   Blue grosbeak Guiraca caerulea 1.86 0.00 1014
Carolina wren Thryothorus ludovicianus 1.01 0.03 1,118   Lazuli bunting Passerina amoena 0.14 ns 417
Bewick's wren Thryomanes bewickii -0.35 ns 594   Indigo bunting P. cyanea -0.57 ns 1725
House wren Troglodytes aedon 1.55 0.00 1,924   Painted bunting P. ciris -3.21 0.00 269
Winter wren T. troglodytes 2.25 ns 659   Dickcissel Spiza americana -1.58 0.02 791
Golden-crowned kinglet Regulus satrapa -0.01 ns 541   Green-tailed towhee Pipilo chlorurus 0.41 ns 212
Ruby-crowned kinglet R. calendula -1.31 ns 656   Rufous-sided towhee P. erythrophthalmus -1.99 0.00 1951
California towhee P. californicus -0.22 ns 113   Red-winged blackbird Agelaius phoeniceus -1.06 0.01 2760
Brown towhee P. fuscus -2.67 0.00 83   Tricolored blackbird A. tricolor 4.83 ns 69
Cassin's sparrow Aimophila cassinii -2.85 0.00 171   Eastern meadowlark Sturnella magna -2.18 0.00 1742
Chipping sparrow Spizella passerina -0.04 ns 2300   Western meadowlark S. neglecta -0.56 ns 1334
Clay-colored sparrow S. pallida -1.31 0.02 444   Yellow-headed blackbird Xanthocephalus xanthocephalus 1.53 ns 649
Brewer's sparrow S. breweri -3.68 0.00 376   Field sparrow S. pusilla -3.25 0.00 1581
Brewer's blackbird Euphagus cyanocephalus -1.15 0.06 1006   Vesper sparrow Pooecetes gramineus -0.25 ns 1488
Great-tailed grackle Quiscalus mexicanus 7.40 0.00 198   Lark sparrow Chondestes grammacus -3.42 0.00 935
Boat-tailed grackle Q. major 2.52 0.05 118   Black-throated sparrow Amphispiza bilineata -3.78 0.02 225
Common grackle Q. quiscula -1.44 0.00 2196   Sage sparrow A. belli -2.43 ns 210
Bronzed cowbird Molothrus aeneus -1.12 ns 55   Lark bunting Calamospiza melanocorys -2.86 0.03 359
Brown-headed cowbird M. ater -0.88 0.06 2780   Savannah sparrow Passerculus sandwichensis -0.57 ns 1461
Orchard oriole Icterus spurius -1.38 0.03 1313   Baird's sparrow Ammodramus bairdii -1.52 ns 134
Baltimore oriole I. galbula 0.26 ns 1594   Grasshopper sparrow A. savannarum -4.48 0.00 1479
Bullock's oriole I.g. bullockii -0.81 ns 614   Fox sparrow Passerella iliaca 0.44 ns 224
Scott's oriole I. parisorum 2.26 ns 113   Song sparrow Melospiza melodia -0.80 0.09 2079
Pine grosbeak Pinicola enucleator 6.36 0.01 152   Lincoln's sparrow M. lincolnii 3.99 0.02 420
Purple finch Carpodacus purpureus -1.19 0.05 921   Swamp sparrow M. georgiana 0.50 ns 783
Cassin's finch C. cassinii 1.27 ns 235   White-throated sparrow Zonotrichia albicollis -1.44 0.01 635
House finch C. mexicanus -0.14 ns 1,420   White-crowned sparrow Z. leucophrys -1.91 0.01 274
Red crossbill Loxia curvirostra 2.13 ns 438   Slate-colored junco Junco hyemalis -0.47 ns 545
White-winged crossbill L. leucoptera -5.52 0.09 155   Oregon junco J.h. oregonus -1.23 0.08 341
Pine siskin Carduelis pinus 0.38 ns 778   Gray-headed junco J.h. caniceps 2.04 ns 50
Lesser goldfinch C. psaltria -1.22 ns 281   McCown's longspur Calcarius mccownii 8.32 0.00 68
American goldfinch C. tristis -1.06 0.03 2165   Chestnut-collared longspur C. ornatus 0.62 ns 153
Evening grosbeak Coccothraustes vespertinus -0.37 ns 596   Bobolink Dolichonyx oryzivorus -1.33 0.01 1147
House sparrow Passer domesticus -1.65 0.00 2557  

*ns--not significant.
For further information:
Bruce G. Peterjohn
National Biological Service
Patuxent Environmental Science Center
Laurel, MD 20708
References
ESRI. 1992. Understanding GIS: the Arc/Info method. Environmental Systems Research Institute, Inc., Redlands, CA. 416 pp.

Geissler, P.H., and J.R. Sauer. 1990. Topics in route-regression analysis. Pages 53-56 in J.R. Sauer and S. Droege, eds. Survey designs and statistical methods for the estimation of avian population trends. U.S. Fish and Wildlife Service Biological Rep. 90(1).

Isaaks, E.H., and R.M. Srivastava. 1989. An introduction to applied geostatistics. Oxford University Press, New York. 561 pp.

 Peterjohn, B.G., and J.R. Sauer. 1993. North American Breeding Bird Survey annual summary 1990-1991. Bird Populations 1:52-67.

Robbins, C.S., D. Bystrak, and P.H. Geissler. 1986. The Breeding Bird Survey: its first fifteen years, 1965-1979. U.S. Fish and Wildlife Service Resour. Publ. 157. 196 pp.

Robbins, C.S., J.R. Sauer, R.S. Greenberg, and S. Droege. 1989. Population declines in North American birds that migrate to the Neotropics. Proceedings of the National Academy of Science USA 86:7658-7662.

Sauer, J.R., and S. Droege. 1990. Recent population trends of the eastern bluebird. Wilson Bull. 102:239-252.


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