BIRD POPULATIONS - Birdpop.org

NORTH AMERICAN BREEDING BIRD SURVEY 2003-2008and 2-yr percentages were generally larger thanthe long-term percentages in the Eastern andCentral regions is encouraging and, despitemany having credible intervals that span 50%,this is still indicative of progress and suggestivethat conditions may have improved forgrassland birds in recent years. Scrub/successional species also have declineddramatically in some areas so increases duringthe 6-yr and 2-yr intervals, relative to the longterm,were of special interest (Fig. 1D).Unfortunately, estimates during these intervalswere comparatively imprecise and additionalyears of favorable population change will beneeded before a reversal in the long-termdeclines would become apparent.Wetland and woodland species exhibited thegreatest overall number of increasing trendsamongst the habitat groupings (Figs. 1C, E).Within the 2003-2008 period of growth, theEastern region experienced the fewest number ofwetland-breeding population gains, but eventhis proportion was above 75%. Woodland birds,on the other hand, experienced their greatestproportional increases in the Eastern regionduring both the 6-yr (74%) and 2-yr (56%) terms,with fewer gains observed in the Central regionthan might have been expected. The survey-widelong-term trend of the wetland group wasslightly lower than that reported in the previousBBS summary, while the woodland group valuewas slightly higher.Detailed analyses of regional patterns ofpopulation trends within individual species arebeyond the scope of this paper. Species-specifictrend and relative abundance data, as well asadditional information regarding the survey areavailable at the North American Breeding BirdSurvey home page (http://www.pwrc.usgs.gov/BBS/).ACKNOWLEDGMENTSWe thank the thousands of volunteers whocontributed time, expertise, and energy to theBBS program during 2003-2008, as well as thosewho participated in earlier years. We are alsograteful for the careful review and constructivecomments provided by B. Peterjohn and S.Droege on the manuscript.LITERATURE CITEDAMERICAN ORNITHOLOGISTS’ UNION. 1998. Check-list ofNorth American Birds. 7th edition. AmericanOrnithologists’ Union, Washington, D.C.ARGUEZ, A. (ed.). 2007. State of the Climate in 2006.Bulletin of the American Meteorological Society88:S1-S135.BYSTRAK, D. 1981. The North American Breeding BirdSurvey. Pp. 34-41 in C.J. Ralph and J.M. Scott (eds.),Estimating Numbers of Terrestrial Birds. Studies inAvian Biology6.LARKIN, N.K., AND D.E. HARRISON. 2002. ENSO warm(El Niño) and cold (La Niña) event life cycles:Ocean surface anomaly patterns, their symmetries,asymmetries, and implications. Journal of Climate15:195–213.LEVINSON, D.H., AND J.H. LAWRIMORE (eds.). 2008. Stateof the Climate in 2007. Bulletin of the AmericanMeteorological Society 89:S1-S179.LINK, W.A., AND J.R. SAUER. 1998. Estimatingpopulation change from count data: application tothe North American Breeding Bird Survey.Ecological Applications 8:258-268.LINK, W.A., AND J.R. SAUER. 2002. A hierarchical modelof population change with application to CeruleanWarblers. Ecology 83:2832-2840.MORRISON, S.A., AND D.T. BOLGER. 2002. Variation in asparrow’s reproductive success with rainfall: foodand predator-mediated processes. Oecologia133:315–324.NOTT, P.M., D.F. DESANTE, R.B. SIEGEL, AND P. PYLE.2002. Influences of the El Nino/SouthernOscillation and the North Atlantic Oscillation onavian productivity in forests of the PacificNorthwest of North America. Global Ecology &Biogeography 11:333-342.PARDIECK, K.L., AND J.R. SAUER. 2000.The 1995-1999summary of the North American Breeding BirdSurvey. Bird Populations 5:30-48.PARDIECK, K.L., AND J.R. SAUER. 2007. The 1999-2003summary of the North American Breeding BirdSurvey. Bird Populations 8:28-45.PETERJOHN, B.G., AND J.R. SAUER. 1993. North AmericanBreeding Bird Survey annual summary 1990-1991.Bird Populations 1:1-15.PETERJOHN, B.G., J.R. SAUER, AND W.A. LINK. 1994. The1992 and 1993 summary of the North AmericanBreeding Bird Survey. Bird Populations 2:46-61.PETERJOHN, B.G., J.R. SAUER, AND W.A. LINK. 1996. The1994 and 1995 summary of the North AmericanBreeding Bird Survey. Bird Populations 3:48-66.PETERSON, T.C., AND M.O. BARINGER (eds.). 2009. Stateof the Climate in 2008. Bulletin of the AmericanMeteorological Society 90:S1-S196.[99]