Population changes of urban land birds in the three years following the hurricane Katrina flood

Abstract

There are few studies of wildlife population dynamics in the wake of natural disasters, and little is known about “normal” rates and trajectories of their recovery. I document the population trajectories of ten urban resident land bird species in New Orleans, USA, over a 30 km network of survey transects in the 3.4 years following the Hurricane Katrina flood of September 2005 and compare them to transects surveyed before the storm in 1994–2000. The avian community in January 2009 differed from that before the storm, chiefly in the increased dominance of European Starlings (Sturnus vulgaris) and the near disappearance of the formerly common Northern Cardinal (Cardinalis cardinalis), Common Grackle (Quiscalis quiscula), and Bronzed Cowbird (Molothrus aeneus; at least through August 2007). In total, resident populations after 3.4 years were at less than half the levels recorded before the storm, having increased only weakly from their post-storm lows. Individual species varied widely in their population changes over the 3 years that followed their initial declines, some declining farther and others increasing by more than threefold. Starlings regained the highest proportion of their pre-storm numbers. The first and probably the second nesting seasons after the storm both saw resident bird populations increase substantially, but then decline again markedly by mid-winter.