Censusing Pheasants by Detonations

Abstract

A study of the ecology and management of the ring-necked pheasant (Phasianus c. torquatus) was begun in Nebraska in the spring of 1941. Prime among the objectives of the survey was to devise some method by which the populations could be estimated or counted. In conjunction with roadside counts as practiced in Minnesota, Iowa, Ohio, Pennsylvania and other states, attempts were made to derive a closer estimate than by that method. Every game technician working with roadside counts of pheasants realizes the difficulties involved. Having had success in estimating the numbers of mourning doves by counting their calls (McClure, H. E., Journ. Wildl. Mgt. 3: 323-328, 1939) a similar study of the calling of pheasants was undertaken. Throughout the summer of 1941 it was found that an average rooster in morning and evening, while establishing, feeding in, or surveying his grounds, would call at intervals of approximately 2 minutes. During these observations it was noted that these birds responded by crowing following thunder, blasting, or the explosions of shot guns. Even such noises as the slamming of a car door or banging on a metal tub would stimulate them to crow. An attempt was made, therefore, to devise a method whereby this peculiar response could be utilized. Four sizes of aerial bombs, commonly called Day-go bombs, were purchased from a fireworks company. The volumes of explosive used in these bombs is at present a military secret, but they cost 10 to 50 cents apiece. In preliminary tests, observers were placed at one quarter, one half, and one mile intervals in various directions from the bombs. It was determined that pheasants would respond by crowing to these explosions at distances up to three miles or more. For practical purposes the 10-cent bomb had the advantage of not being so loud as to deafen the observer's ears, but loud enough to stimulate the birds for a mile or more. With all sizes of bombs, pheasants less than 200 yards away were frightened into silence. In calm weather birds crowing more than a mile away may be heard. Firecrackers placed on the ground did not elicit as uniform a response from the birds, nor did the discharge of a shot gun. This is explained by the fact that sound travels upward and outward from a fire cracker, and is directed forward by the gun. The explosion from an aerial bomb travels downward and outward, simulating thunder, and it results in a more uniform response. The most critical weather condition from the standpoint of the observer is the presence and amount of wind. Wind carries the sound of the bomb away, prevents distant calls from reaching the observer, and whistles by the observers' ears so that he cannot hear nearby calls. A simple rule is not to attempt to stimulate the birds by these bombs when there is a wind strong enough (about 5 miles per hour) to blow out the match used to light the fuse. In Nebraska there usu-