BY
HARRISON B. TORDOFF AND ROBERT M. MENGEL
Contents
| PAGE | |
| Introduction | [4] |
| Accidents to Migrating Birds in early October, 1954 | [6] |
| General | [6] |
| Accidents at Topeka, Kansas | [6] |
| Description of WIBW-TV tower | [7] |
| Weather conditions | [7] |
| Acknowledgments | [7] |
| Notes on the Species Killed at Topeka | [8] |
| Randomness of the Sample | [17] |
| Number of Migrants | [18] |
| Differential Migration of Sex- and Age-classes | [20] |
| History of the subject | [20] |
| Differential migration of sex- and age-classes as shown by the Topeka sample | [23] |
| Molt in Relation to Migration | [29] |
| General comment | [29] |
| Molt in the Topeka sample | [30] |
| Size Differences according to Sex and Age | [31] |
| Linear measurements | [31] |
| Weights | [32] |
| Computations of Longevity and Survival | [38] |
| Processing of Samples | [38] |
| Summary | [39] |
| Literature Cited | [41] |
Introduction
This paper is primarily an analysis of a sample of migrant birds killed in the autumn of 1954 by striking a television tower one mile west of Topeka, Shawnee County, Kansas. Secondarily, some aspects of migration involved in studies of this kind are discussed and historical background is presented.
Considerable interest has been occasioned in recent years in the eastern United States by large-scale accidents to night-migrating birds. Most accidents have occurred in the autumn. The widespread adoption by airports of an instrument called the ceilometer, which measures the height of cloud ceilings by reflecting from them a high-powered beam of light, has proved under certain conditions to be catastrophic to night-flying birds. Among the recent reports of such accidents are those of Spofford (1949) and Laskey (1951) for Nashville, Tennessee, Howell and Tanner (1951) for Knoxville, Tennessee, and Lovell (1952) for Louisville, Kentucky. Recently Howell, Laskey, and Tanner (1954) reviewed ceilometer "tragedies" without being able to determine the exact reason for their lethal effectiveness. Less publicized so far have been mass collisions of birds with another class of obstacles, tall radio and television towers. These slender towers, usually 500 to 1000 feet tall, are increasing rapidly in numbers and there is reason to suppose that they will take a correspondingly larger toll of bird life.
Notice has long been given by ornithologists to mass destruction of birds by more conventional solid obstructions to passage, and newspapers occasionally mention birds killed at such well-known points as the Washington Monument and the Empire State Building.
Seventy-five years ago, J. A. Allen (1880) published the results of questionnaires circulated by William Brewster to lighthouse keepers. Brewster himself (1886) described destruction of birds at a lighthouse in the Bay of Fundy, paying keen attention to behavior of the birds and the exact conditions under which nocturnal flight and accidents occurred. The subject also received attention in several countries across the Atlantic. Destruction of birds at Irish lighthouses was carefully noted over a period of years and the results were published periodically, culminating in R. M. Barrington's massive report (1900) which remains in some ways the most thorough of its type.