A method for investigating avian predation on the adult Black Hills beetle
Date
1963
Authors
Stallcup, Patrick Lloyd, author
Baldwin, Paul H., advisor
Wygant, Noel D., committee member
Lechleitner, Robert R., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Procedures for investigating avian predation on the adult Black Hills beetle, Dendroctonus ponderosae Hopkins, during the period off light and attack of this insect were developed and tested. Field work was conducted during the months of June, July, and August of 1961 and 1962 in two stands of ponderosa pine of about 50 acres each near Bailey, Park County, Colorado. The density of the population of beetles per 10 acres was computed from average number of beetles found in samples of infested bark. The relative intensity of beetles emerging and flying per day was determined from counts of beetles collected from cages installed on infested trees. Birds were censused along a census transect. The total area censused for each species was calculated and based on the greatest distance of recognition of birds which varied with density of forest and conspicuousness of each species of bird. The average number of birds per 10 acres was computed from 49 censuses taken throughout the summer. During the period of most intense emergence of the Black Hills beetle, birds were collected in an adjacent stand. The collected specimens were classified into feeding-categories and the stomach contents of each member of each category were examined for fragments of Black Hills beetles. Each feeding-category was analyzed as a single entity. The average proportion of fragments of beetles in the food of members of each feeding-category was estimated visually. These proportions were converted to equivalent weights that they constituted of the estimated weights of food consumed by these birds daily. These weights of fragments of beetles were converted to equivalent numbers of beetles. The average number of beetles eaten by members of each feeding-category during the period of most intense emergence of the beetle was computed. This computation was based on the number of birds of each feeding-category censused per 10 acres and the average number of beetles consumed by then. The proportion of the population of beetles consumed by birds was calculated to be 8.5 per cent. The 95 per cent confidence interval of this figure is from zero to 43.3 per cent. Field observations indicated that mortality of the Black Hills beetle during the previous winter was abnormally high. Considering this high winter mortality, the proportion of the population of beetles removed by birds was computed to be 11.6 per cent. The 95 per cent confidence interval on this figure is from zero to 59.5 per cent.
Description
Covers not scanned.
Print version deaccessioned 2021.
Print version deaccessioned 2021.
Rights Access
Subject
Insect pests -- Control -- Biological Control
Mountain pine beetle
Citation
Associated Publications
Meiman, James R. Little South Poudre Watershed and Pingree Park Campus. Colorado State University, College of Forestry and Natural Resources (1971). http://hdl.handle.net/10217/70382