18 December 2010

A Tally of Towers and Towerkills

More than 100,000 communication towers are estimated as occurring within the United States. These structures range in height from 200 to more than 800 feet. There is an estimated annual growth of 7-10 percent.

Each of these towers are registered with the Federal Communications Commission, making it possible to evaluate their occurrence and extent. The best site to view tower type and location is the towerkill.com website, which provides a map for each state in the continental U.S., and a tally of the types of towers present in 1998, 2004 and 2001.

The following summary for four states in the northern Great Plains, readily shows the increase in towers, based upon a comparison of 1998 to 2010, as summarized from the towerkill.com information.

Kansas

1998

2010

200-299 feet

342

535

300-499 feet

599

1002

500-799 feet

60

71

800+ feet

14

40

1015

1648

Nebraska

200-299 feet

212

330

300-499 feet

344

560

500-799 feet

35

44

800+ feet

31

34

622

968

South Dakota

200-299 feet

149

209

300-499 feet

142

241

500-799 feet

18

26

800+ feet

19

21

328

497

North Dakota

200-299 feet

200

260

300-499 feet

179

342

500-799 feet

17

27

800+ feet

19

19

415

648

Overall

200-299 feet

903

1334

300-499 feet

1264

2145

500-799 feet

130

168

800+ feet

83

114

Total

2380

3761

Increasing numbers are readily apparent for other states and regions.

Examples of Bird Mortality

There are several prominent examples of bird mortality at communication towers. Some examples include:

1948: a large kill at a radio tower near Baltimore, Maryland

1955 and for 29 subsequent years: a minimum of 42,384 records, representing 189 species at a television tower at the Tall Timbers Research Station in northern Florida

1957 and for the subsequent 38 years: nearly 121,560 records for 123 species

1963: more than 12,000 birds retrieved from the base of a tall television tower in Eau Clair, Wisconsin

1972: reports of single night kills exceeding 1000 birds at television towers in Tennessee and Florida

1982 and subsequent years: variable numbers from 4,782 in 1982 to 6 in 1992 at three tall television towers in Buffalo, New York;

1983: 320 casualties, representing 40 species, during September 12-16, at the KCNA-TV Tower in Boone County, Nebraska; the specimens are now in the collection at Wayne State College.

2003-2005: multiple tower study, with 203 birds noted in spring 2005 at 24 towers, and 173 during the autumn at the same towers

2005: On September 7-8 and also on September 13-14, an estimated 400 birds killed each night at the 1,100 foot WMTV tower near Madison, Wisconsin.

2005: more than 500 killed in a three-night period during October at an 1,100 foot height tower near West Monroe, New York.

Further information on additional known tower kills is readily available at numerous online sources.

Based upon the extensive number of known towers of varying heights, and the relative few reports, it is obvious that little information is available on the probable, and wide-spread occurrence of mortality. The recent studies in Michigan are an exception, and further indicate how dangerous towers can be for migratory birds of many sorts. Similar results would result from similar efforts wherever towers occur.