Avian mortality at communication towers in the United States and Canada: which species, how many, and where?

Authors

Travis Longcore, The Urban Wildlands GroupFollow
Catherine Rich, The Urban Wildlands GroupFollow
Pierre Mineau, National Wildlife Research CentreFollow
Beau MacDonald, The Urban Wildlands GroupFollow
Daniel G. Bert, Carleton UniversityFollow
Lauren M. Sullivan, University of California, Los Angeles
Erin Mutrie, National Wildlife Research CentreFollow
Sidney A. Gauthreaux Jr., Clemson UniversityFollow
Michael L. Avery, USDA/APHIS/WS National Wildlife Research CenterFollow
Robert L. Crawford, United States Department of Agriculture/Wildlife ServicesFollow
Albert M. Manville II, U.S. Fish and Wildlife ServiceFollow
Emilie R. Travis, University of WisconsinFollow
David Drake, University of WisconsinFollow

Document Type

Article

Date of this Version

2013

Citation

Biological Conservation 158 (2013) 410–419; http://dx.doi.org/10.1016/j.biocon.2012.09.019

Abstract

Birds migrating to and from breeding grounds in the United States and Canada are killed by the millions in collisions with lighted towers and their guy wires. Avian mortality at towers is highly variable across species, and the importance to each population depends on its size and trajectory. Building on our previous estimate of avian mortality at communication towers, we calculated mortality by species and by regions. To do this, we constructed a database of mortality by species at towers from available records and calculated the mean proportion of each species killed at towers within aggregated Bird Conservation Regions. These proportions were combined with mortality estimates that we previously calculated for those regions. We then compared our estimated bird mortality rates to the estimated populations of these species in the United States and Canada. Neotropical migrants suffer the greatest mortality; 97.4% of birds killed are passerines, mostly warblers (Parulidae, 58.4%), vireos (Vireonidae, 13.4%), thrushes (Turdidae, 7.7%), and sparrows (Emberizidae, 5.8%). Thirteen birds of conservation concern in the United States or Canada suffer annual mortality of 1–9% of their estimated total population. Of these, estimated annual mortality is >2% for Yellow Rail (Coturnicops noveboracensis), Swainson’s Warbler (Limnothlypis swainsonii), Pied-billed Grebe (Podilymbus podiceps), Bay-breasted Warbler (Setophaga castanea), Golden-winged Warbler (Vermivora chrysoptera), Worm-eating Warbler (Helmitheros vermivorum), Prairie Warbler (Setophaga discolor), and Ovenbird (Seiurus aurocapilla). Avian mortality from anthropogenic sources is almost always reported in the aggregate (‘‘number of birds killed’’), which cannot detect the species-level effects necessary to make conservation assessments. Our approach to per species estimates could be undertaken for other sources of chronic anthropogenic mortality.