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Crowing Counts as Indices to Cock Pheasant Populations in Wisconsin
John M. Gates
The Journal of Wildlife Management
Vol. 30, No. 4 (Oct., 1966), pp. 735-744
Stable URL: http://www.jstor.org/stable/3798280
Page Count: 10
You can always find the topics here!Topics: Sex ratio, Censuses, Population density, Pheasants, Chickens, Population dynamics, Weather conditions, Wildlife management, Weather, Arithmetic mean
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Reliability of the crowing count was investigated in 1959-64 on an area of known pheasant populations in east-central Wisconsin. Certain assumptions implicit in use of the crowing count as a population index were tested: (1) that the timing of counts was uniform each year in relation to the seasonal trend in crowing, (2) that a constant fraction of the cock population was crowing at all density levels, (3) that annual variations in sex ratios did not influence crowing behavior, and (4) that crowing intensity was independent of population density. Only the latter assumption was rejected. Crowing intensity increased about 8 percent per unit increase of 100 cocks on the study area. This degree of bias was regarded as relatively unimportant operating over the narrow range of year-to-year population change in the present study. Since population levels often differ to a greater extent between areas than they do between years in the same area, density bias may be more important where crowing counts are used for regional comparisons. The importance of making crowing counts only under optimal weather conditions in order to minimize sampling error is stressed. Under Wisconsin conditions, the crowing count appeared to be reliable as an annual index to cock pheasant populations.
The Journal of Wildlife Management © 1966 Wiley