Date of Award
1-10-2013
Document Type
Dissertation
Degree Name
Environmental Sciences, Ph.D.
First Advisor
Richard Grippo
Committee Members
Joelle Gehring; Martin Huss; Robert Engelken; Thomas Risch
Call Number
LD 251 .A566d 2012 A36
Abstract
Nearctic-Neotropical migrants are a charismatic group of birds that occupy two distinct and often distant habitats for breeding and winter phases of their annual cycle. The migratory journey between these phases poses the greatest threat to populations because of the increased exposure to anthropogenic sources of mortality. Fatal collisions with communication towers are one of many anthropogenic sources of mortality. I conducted a four-year investigation into the impacts of communication tower structures in Arkansas on migrating songbirds by searching 28 randomly-selected towers for carcasses and feather piles from spring 2005 through fall 2008. Tall towers (<150 m AGL) negatively impacted significantly more birds than short towers (61 - 150 m AGL), and I found significant but inconsistent evidence that towers with red lighting systems at night were associated with significantly more fatalities than towers with white lighting systems. Tower search technicians recovered 32.9% of placed bird carcasses. Scavengers removed placed bird carcasses at a rate of approximately 10% per day. Results from searcher efficiency and carcass removal rates confirm that the use of recovered carcasses to quantify the loss of birds at communication towers results in negatively biased estimates, indicating that the number of birds lost to communication towers annually is likely much higher than the number of carcasses and feather piles from towers. Data from my study as well as that from two contemporary studies in Michigan and Wisconsin show that opting for shorter towers, or towers less than 150 m AGL, can significantly reduce the number of avian fatalities annually as well as reduce the probability a mass collision event may occur. Furthermore, the use of white aviation safety lighting systems instead of red offers a relatively inexpensive way to further mitigate the threat posed to migrating birds by communication towers.
Rights Management
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Aylsworth, Erin Tighe, "Factors Influencing the Loss of Migratory Birds at Communication Towers" (2013). Student Theses and Dissertations. 850.
https://arch.astate.edu/all-etd/850
