Height, Guy Wires, and Steady-Burning Lights Increase Hazard of Communication Towers to Nocturnal Migrants: A Review and Meta-Analysis

摘要

The ornithological literature contains frequent reports of birds killed at lights (see references in class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b87')">Weir 1976, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b6')">Avery et al. 1980, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b49')">Kerlinger 2000, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b33')">Gauthreaux and Belser 2006). Two long-term studies with periodic searches confirmed that large numbers of birds can be killed at communication towers: (1) a 38-year study of a single 305-m television tower in west central Wisconsin documented 121,560 birds of 123 species killed (class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b48')">Kemper 1996), and (2) a 29-year study at a Florida television tower documented the deaths of 44,007 birds of 186 species (class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b23')">Crawford and Engstrom 2001). Because the FCC does not require monitoring of avian mortality at towers that it registers or otherwise approves, and because tower operators do not monitor mortality, bird kills reported in the literature represent only a minimum measurement of total mortality. Most sites are never visited to find dead birds, and most of those that are surveyed are visited only sporadically. Despite a number of useful reviews of the topic (class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b87')">Weir 1976, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b6')">Avery et al. 1980, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b83')">Trapp 1998, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b49')">Kerlinger 2000) and recent progress on key issues such as the influence of lighting type and tower height (e.g., class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b46')">Jones and Francis 2003, class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b33')">Gauthreaux and Belser 2006, Gehring et al. unpubl. data), an analytical synthesis of factors influencing avian mortality at towers would aid policy development and focus future research. Here, we ask how design and placement of towers affect mortality of birds. Many variables influence rates of bird mortality at communication towers; certain types of weather conditions (e.g., frontal systems) are implicated in most large kills (see review in class="ref NLM_xref-bibr" href="javascript:popRef2('i0004-8038-125-2-485-b33')">Gauthreaux and Belser 2006). Inclement weather and other physical variables, such as the effects of the lunar cycle, are beyond the control of regulators. Therefore, we concentrate on the elements of tower design that can influence bird mortality and that can be regulated.