Accidents to Migrating Birds in early October, 1954
General.—The few days around the end of the first week of October, 1954, were notable for a series of accidents which occurred to migrating birds over much of eastern United States. So far as we know, these were all associated with an extensive belt of bad weather (cold fronts and stationary fronts) which covered much of the country during that period, and the accidents involved ceilometers and solid structures alike. Accidents known to us occurred as far south as Macon, Georgia (David W. Johnston, letter: Nov. 1, 1954), as far north as New York City, where many migrants were killed at the Empire State Building (New York Times, Thursday, October 7, 1954, p. 1) and elsewhere, and as far west as Smoky Hill Air Force Base at Salina, Kansas (ceilometer, October 7, some birds received at the University of Kansas). Some of the above, and incidents from a number of other localities, were mentioned in varying detail in Audubon Field Notes (vol. 9, no. 1, pp. 6, 10, 15, 17, 18, 32, February, 1955). Still other accidents occurred at Columbia, Missouri (Richard P. Grossenheider, verbal communication), and Topeka, Kansas (present paper). Some probably have escaped our notice; summaries of some of these will probably appear in ornithological journals for some time to come. At Robins Air Force Base near Macon, Georgia, at least 50,000 birds were killed, of which about 2500, representing 54 species, were picked up (Johnston, loc. cit.).
Accidents at Topeka, Kansas.—At Topeka, Shawnee County, Kansas, all birds were killed by collision with the newly-erected (1954) television transmitting tower of station WIBW-TV. This tower is one mile west of the city.
The first casualties (see Table 1 for all others) were a Sora (Porzana carolina) and a Yellow-bellied Flycatcher (Empidonax flaviventris) found on September 7. The major accidents, however, occurred on the nights of September 24-25, September 30-October 1, October 5-6, and October 6-7. Totals of birds picked up (probably over 95 per cent of birds killed) are given in Table 1, in which each date given is that of the day after the kill, i. e., the date on which the birds were collected.
All major kills occurred on cloudy and foggy nights associated with frontal weather. Throughout the period a few birds struck the tower even on fairly clear nights, and minor but appreciable "falls" occurred on the nights of October 4-5, 7-8, and 22-23. A few birds killed probably were overlooked for a time and found their way into later samples. This is especially probable in the case of some birds entered under date of October 23, as many of these were somewhat desiccated. Weights clearly altered by desiccation or mutilation were not recorded. Reports of these accidents have been published by Carson (1954 a, b, and c).
According to Carson (1954c:27), the majority of birds killed on nights of heavy flight fell "between three and four o'clock in the morning when skies were overcast and a cool front moved in from the north. Due to the cooperation of the watchmen it is thought that most of the birds that were killed were recovered. Of course some injured birds in hiding were not found and some were lost to predators."
Description of WIBW-TV TOWER.—The tower is 950 feet tall and stands on a hill approximately 1000 feet above sea level. The fact that the tower is on a hill places the top of the tower at 1010 feet above the elevation of the average local terrain. The tower is triangular in cross-section, each face seven feet wide, and is constructed of six-inch steel L-beams with three-inch cross-members every seven feet and smaller diagonal cross-members. It has no taper and bears a transmitting antenna on the top. The tower is supported by 12 guy wires, 3 wires attaching at each of 4 levels. The cables extend south, WNW, and NNE from the tower and are 1-1/2 inches in diameter. The tower is lighted by a series of red lights, some flashing and others steady. The transmitter was not in operation when the accidents took place.
Weather conditions.—All major kills at Topeka occurred when migrating birds encountered either a cold front or a stationary front lying over eastern Kansas. Typically, this frontal weather included rain, fog, and cloud ceilings down to as low as 800 to 1000 feet. Weather of this type presumably forces the migrating birds to fly below the cloud ceiling and thus brings them within the altitudinal range of the television towers.