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State of the Birds
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North American bird species undergoing the greatest population declines from 1966 to 2003
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These population declines are measured by the Breeding Bird Survey, a survey that is done by volunteers across North America and is coordinated and analyzed by the U.S. Geological Survey at the Patuxent Wildlife Research Center. Declines are shown as percentage population loss from 1966 to 2003. The list includes all species encountered on 20 or more BBS routes and with population losses of more than two-thirds between 1966 and 2003 (averaging –3.0% per year or greater).
Population size estimates are from North American Waterfowl Management Plan, Partners in Flight, U.S. Shorebird Conservation Plan, Waterbirds for the Americas, and Wetlands International.
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Species with large sample sizes (more than 95 routes included in the analysis):
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Population loss 1966-2003
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2003 population estimate
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1
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Rusty Blackbird
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-97.9%
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2,000,000
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2
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Henslow's Sparrow
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-96.4%
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79,000
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3
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Common Tern
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-90.6%
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1,400,000
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4
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Verdin
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-85.6%
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8,900,000
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5
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Sprague's Pipit
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-83.8%
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870,000
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6
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Pinyon Jay
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-82.5%
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4,100,000
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7
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Short-eared Owl
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-80.3%
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2,400,000
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8
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Cerulean Warbler
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-79.6%
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560,000
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9
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Black-throated Sparrow
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-79.6%
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27,000,000
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10
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Loggerhead Shrike
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-77.1%
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4,200,000
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11
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Grasshopper Sparrow
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-77.1%
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15,000,000
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12
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Olive-sided Flycatcher
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-73.2%
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1,200,000
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13
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Baird's Sparrow
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-73.2%
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1,200,000
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14
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Canyon Wren
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-70.0%
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660,000
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15
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Field Sparrow
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-68.8%
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8,200,000
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16
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Northern Bobwhite
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-67.6%
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9,200,000
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Species with small sample sizes (fewer than 96 but more than 19 routes included in the analysis):
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Population loss 1966-2003
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2003 population estimate
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1
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Lesser Yellowlegs
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-97.3%
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500,000
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2
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King Rail
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-94.8%
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63,000
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3
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Black Swift
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-93.9%
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150,000
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4
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Harris' Hawk
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-88.1%
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390,000
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5
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Bendire's Thrasher
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-86.1%
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170,000
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6
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Mottled Duck
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-86.1%
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690,000
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7
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Black-chinned Sparrow
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-85.6%
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390,000
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8
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Greater Prairie-Chicken
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-78.8%
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690,000
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9
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Purple Gallinule
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-77.9%
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< 500,000
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10
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Horned Grebe
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-70.0%
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< 500,000
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