Bird and bat mortality resulting from collisions with manmade towers is well-documented, and our understanding of this phenomenon is increasing, particularly for taller structures (!61 m) with guy wires and the obstruction lighting required by the U.S. Federal Aviation Administration. However, shorter, monopole tower designs remain underinvestigated. We report the results of a 3-year study (2006)(2007)(2008) on the effects of 2 existing telecommunication (''cell phone'') towers on migratory bird and bat mortality in Rock Creek Park (ROCR), Washington, D.C., USA. The towers in ROCR are the shorter (30.9 m and 39.6 m in ht), monopole design and lack obstruction lighting and guy wires. We conducted mortality surveys on a daily basis during spring and autumn migrations, and conducted weekly surveys during the summer. Bird carcasses were collected, but we were unable to attribute any avian or bat mortality to the towers at these sites. ß 2012 The Wildlife Society. Research to date makes it evident that several factors are involved in bird and bat deaths at communication towers, including 1) tower characteristics (particularly ht, the presence of guy wires, and lighting scheme), 2) weather conditions, 3) bird and bat behavior at towers, 4) timing of peak migration periods for nocturnal migrants, and 5) topography (Longcore et al. 2008). Critically, the interaction of tower height and design coupled with specific weather conditions (rain, fog, and/or low cloud cover, associated with weather fronts) is a major contributor to mortality risk.Recommendations based on our understanding of how these factors interact to kill birds and bats at communication towers are now being used to decrease the number of fatalities at these structures, as well as to develop monitoring guidelines to assist in on-going research. Taller towers (!61 m) have received the greatest attention in the literature, with most bird and bat mortalities reported at these structures. The extent of mortalities from collisions with shorter (<61 m) towers may be underreported (Manville 2005). The few studies that have been published on kills at short towers have shown that weather and lighting also contribute to mortality at towers approximately 30 m in height (James 1956, Herndon 1973, Wylie 1977.Before concluding that short towers have minimal impact on populations of birds and bats, more research is needed on different short-tower designs under a range of environmental conditions (Manville 2005). The objective of this study was to increase our understanding of mortality at cell towers by investigating whether unlighted, unguyed, short towers without U.S. Federal Aviation Administration (FAA) obstruction lighting pose a threat to migratory birds and bats.