BY HARRISON B. TORDOFF AND ROBERT M. MENGEL University of Kansas Lawrence 1956 University of Kansas Publications, Museum of Natural History Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson Volume 10, No. 1, pp. 1-44, 6 figures in text, 2 tables Published September 12, 1956 University of Kansas Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1956 26-3856 Studies of Birds Killed in Nocturnal Migration BY HARRISON B. TORDOFF AND ROBERT M. MENGEL...

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 ado

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. Johns

We gratefully acknowledge our debt to the Topeka Audubon Society for making this study possible by carefully collecting birds killed at the television tower. L. B. Carson deserves special mention for his general supervision of the bird collecting by the members of the Topeka Audubon Society. Members of the Society and others who picked up birds under the television tower were: Mrs. Lloyd Biggs, Elaine Carson, L. B. Carson, Jesse A. Eddy, Elizabeth Fisher, Mrs. Walter Huxman, Florence McKinney, M

A list of numbers and kinds of birds killed is given in Table 1. Discussion of data afforded by certain species for which, large samples were available will be found below. There are additionally certain data afforded by the sample and certain comments to be made on various species which can be handled most conveniently in an annotated list. In this list we have included all weight data (still scarce for many North American birds), comments on status in Kansas of various species, results of comp

The reliability of certain of the conclusions which might be drawn from data of the kind presented herein depends largely on the randomness of the sample. To what degree does this sample provide a true cross-section of the nocturnal migrants present over the area on a given night or succession of nights? As far as the relative abundance of species in the sample is concerned, there is little doubt that it is not at all random. The absence of such species as the Gray-cheeked Thrush ( Hylocichla mi

If it can be assumed that nocturnally migrating birds are approximately uniformly spaced across the sky and that the red lights did not attract birds which would otherwise have missed the tower, it is possible to compute the volume of migration from the sample killed. In regard to the first assumption, both Stone (1906:250-251) and Lowery (1951:409-413) have presented evidence of fairly uniform distribution of nocturnal migrants. We have no information on the second assumption beyond the facts t

History of the Subject. —For a long time it has been known in a general way that old and young birds and males and females of some species do not always migrate at the same times, by the same routes, or even to the same places. This is a subject about which much has been written. Reading the summaries of some general texts, it is easy to acquire the impression that the facts of the matter are well known. On the contrary, they are poorly known and much remains to be learned before differential mi

General comment. —The exact relationship between molt and migration seems not to have been definitely established. The subject has received cursory attention in the literature and conflicting opinions have been expressed. Dwight (1900:126-128) believed that molt is completed or nearly completed before migration in nearly all passerine species that occur in New York save for certain swallows and flycatchers. Molt has since been found to precede migration of at least one of the flycatchers ( Empid

Linear measurements. —Taxonomists long have recognized in many species that males differ in size from females. Less attention, until recently, has been paid to the relative sizes of adult and immature birds. Many taxonomists, however, seem to have had an uneasy suspicion that immature birds are "untrustworthy" in comparison with adults, and immatures have often been excluded from samples when recognizable. Since, however, there are still relatively few reliably aged specimens in collections, for

Tanner (ms., and letter, April 21, 1955) recently devoted considerable ingenuity to computing by actuarial methods the longevity of the Oven-bird, using the adult-immature ratio in samples killed at a ceilometer at Knoxville, Tennessee. Tanner's computations were based on the simple assumption that Further application of such techniques may prove desirable and rewarding. It would seem at present, however, to be a risky procedure, as it has been abundantly shown (see above) that adults and immatu

Thorough processing of large samples of birds killed accidentally is time-consuming. We were fortunate in having considerable assistance; even so, all desirable data could not be obtained from the 1090 birds of the present sample. As aids to others conducting studies of this kind we should mention a few points which may be of assistance. Birds should be picked up as soon as possible after death, certainly by the end of the day after the accident and preferably much sooner. They should be weighed

The foregoing paper discusses accidents in which large numbers of night-migrating birds are killed. A brief historical review of ornithological interest in such occurrences is given, and the types of data provided by the accidents are listed and discussed. In particular, recent accidents occurring in early October, 1954, through much of eastern United States are cited, and detailed analysis is presented of a sample of 1090 birds killed one mile west of Topeka, Shawnee County, Kansas, between Sep

Allen, J. A. 1880. Destruction of birds by light-houses. Bull. Nuttall Orn. Club, 5(3):131-138, July. 1896. Gätke's 'Heligoland.' Auk, 13(2):137-153, April. 1901. Barrington's 'The Migration of Birds at Irish Light Stations.' [Review.] Auk, 18(2):205-206, April. 1909. An American's views of bird migration. Brit. Birds, 3(1):12-19, June 1. Barrington, R. M. 1900. The migration of birds as observed at Irish lighthouses and lightships [ etc. ]. London, R. H. Porter; Dublin, Edward Ponsonby. Pp. XXV