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A. D. Geis

Publications and source records attributed to A. D. Geis.

53 records · Page 3Linked to original sources
USGS1965

Results of woodcock wing collections, 1959 to 1962

During hunting seasons from 1959 to 1962, age and sex determined from 45,444 wings were used to measure annual productivity of woodcocks ( Philohela minor ). Age of birds was determined by pattern and color of secondaries and by wear on primaries. Sex was determined by width and length of primaries. Overall age ratios, weighted by kill estimates, were the same each year and indicated no change in annual productivity. Immature sex ratios in the combined kill were nearly even each year, but kill of adult females was much larger than kill of adult males. The difference in sex ratios between immatures and adults thus suggests higher mortality of males than females after the first hunting season. Since woodcocks are promiscuous, an unbalanced adult sex ratio in favor of females probably does not reduce productivity. There are, however, factors affecting reliability of information deduced from wing collections, and further research is necessary to answer questions on differential vulnerability and mortality rates.

Connecticut, Louisiana, Maine, Massachusetts, Mich↗
USGS1965

A method for estimating fall adult sex ratios from production and survival data

This paper presents a method of utilizing data relating to the production and survival of a bird population to estimate a basic fall adult sex ratio. This basic adult sex ratio is an average value derived from average production and survival rates. It is an estimate of the average sex ratio about which the fall adult ratios will fluctuate according to annual variations in production and survival. The basic fall adult sex ratio has been calculated as an asymptotic value which is the limit of an infinite series wherein average population characteristics are used as constants. Graphs are provided that allow the determination of basic sex ratios from production and survival data of a population. Where the respective asymptote has been determined, it may be possible to estimate various production and survival rates by use of variations of the formula for estimating the asymptote.

Journal of Wildlife Management↗