Douglas Johnson (Former Employee)
Science and Products
Filter Total Items: 318
Forty-third breeding bird census [On selected prairies in east-central North Dakota -- 1979 - Kentucky blue grass prairie and mixed prairie I-V, VIII Forty-third breeding bird census [On selected prairies in east-central North Dakota -- 1979 - Kentucky blue grass prairie and mixed prairie I-V, VIII
Abstract has not been submitted
Authors
Douglas H. Johnson, J.M. Callow
Age determination of mallards Age determination of mallards
A technique for distinguishing adult from yearling wild mallards (Anas platyrhynchos), from late winter through the nesting season, was developed by applying discriminant analysis procedures to selected wing feather characters of 126 yearlings and 76 adults (2-year-olds) hand-reared from wild eggs during 1974, 1975, and 1977. Average values for feather characters generally increased as...
Authors
Gary L. Krapu, Douglas H. Johnson, C.W. Dane
Modeling sandhill crane population dynamics Modeling sandhill crane population dynamics
The impact of sport hunting on the Central Flyway population of sandhill cranes (Grus canadensis) has been a subject of controversy for several years. A recent study (Buller 1979) presented new and important information on sandhill crane population dynamics. The present report is intended to incorporate that and other information into a mathematical model for the purpose of assessing the...
Authors
Douglas H. Johnson
Mathematics and mallard management Mathematics and mallard management
Waterfowl managers can effectively use simple population models to aid in making management decisions. We present a basic model of the change in population size as related to survival and recruitment. A management technique designed to increase survival of mallards (Anas platyrhynchos) by limiting harvest on the Chippewa National Forest, Minnesota, is used to illustrate the application...
Authors
L.M. Cowardin, Douglas H. Johnson
Forty-second breeding bird census - mixed prairie I-V and VIII Forty-second breeding bird census - mixed prairie I-V and VIII
Abstract has not been submitted
Authors
Douglas H. Johnson
Forty-second breeding bird census - Kentucky blue grass prairie Forty-second breeding bird census - Kentucky blue grass prairie
Abstract has not been submitted
Authors
Douglas H. Johnson
Effects of a summer storm on bird populations Effects of a summer storm on bird populations
Abstract has not been submitted
Authors
Douglas H. Johnson
Modeling sandhill crane population dynamics Modeling sandhill crane population dynamics
No abstract available.
Authors
Douglas H. Johnson
Estimating nest success: The Mayfield method and an alternative Estimating nest success: The Mayfield method and an alternative
Mayfield's method for calculating the success of a group of nests is examined in detail. The standard error of his estimator is developed. Mayfield's assumption that destroyed nests are at risk until the midpoint of the interval between visits leads to bias if nests are visited infrequently. A remedy is suggested, the Mayfield-40% method. I also present a competing model, which...
Authors
Douglas H. Johnson
Interpreting the results of nesting studies Interpreting the results of nesting studies
Nesting studies are used to assess the production of birds and to evaluate nesting habitats. Most such studies involve finding nests in a given area and subsequently determining the proportion that hatched. Unfortunately, the results are often biased by unrecognized differences in the probabilities of finding successful and unsuccessful nests. The observed hatch rates of 1,900 nests of...
Authors
H.W. Miller, Douglas H. Johnson
Breeding bird populations of selected grasslands in east central North Dakota -- 1977 - Kentucky blue grass prairie and mixed prairie I-V, VIII Breeding bird populations of selected grasslands in east central North Dakota -- 1977 - Kentucky blue grass prairie and mixed prairie I-V, VIII
Abstract has not been submitted
Authors
Douglas H. Johnson
Some Bayesian statistical techniques useful in estimating frequency and density Some Bayesian statistical techniques useful in estimating frequency and density
This paper presents some elementary applications of Bayesian statistics to problems faced by wildlife biologists. Bayesian confidence limits for frequency of occurrence are shown to be generally superior to classical confidence limits. Population density can be estimated from frequency data if the species is sparsely distributed relative to the size of the sample plot. For other...
Authors
Douglas H. Johnson
Science and Products
Filter Total Items: 318
Forty-third breeding bird census [On selected prairies in east-central North Dakota -- 1979 - Kentucky blue grass prairie and mixed prairie I-V, VIII Forty-third breeding bird census [On selected prairies in east-central North Dakota -- 1979 - Kentucky blue grass prairie and mixed prairie I-V, VIII
Abstract has not been submitted
Authors
Douglas H. Johnson, J.M. Callow
Age determination of mallards Age determination of mallards
A technique for distinguishing adult from yearling wild mallards (Anas platyrhynchos), from late winter through the nesting season, was developed by applying discriminant analysis procedures to selected wing feather characters of 126 yearlings and 76 adults (2-year-olds) hand-reared from wild eggs during 1974, 1975, and 1977. Average values for feather characters generally increased as...
Authors
Gary L. Krapu, Douglas H. Johnson, C.W. Dane
Modeling sandhill crane population dynamics Modeling sandhill crane population dynamics
The impact of sport hunting on the Central Flyway population of sandhill cranes (Grus canadensis) has been a subject of controversy for several years. A recent study (Buller 1979) presented new and important information on sandhill crane population dynamics. The present report is intended to incorporate that and other information into a mathematical model for the purpose of assessing the...
Authors
Douglas H. Johnson
Mathematics and mallard management Mathematics and mallard management
Waterfowl managers can effectively use simple population models to aid in making management decisions. We present a basic model of the change in population size as related to survival and recruitment. A management technique designed to increase survival of mallards (Anas platyrhynchos) by limiting harvest on the Chippewa National Forest, Minnesota, is used to illustrate the application...
Authors
L.M. Cowardin, Douglas H. Johnson
Forty-second breeding bird census - mixed prairie I-V and VIII Forty-second breeding bird census - mixed prairie I-V and VIII
Abstract has not been submitted
Authors
Douglas H. Johnson
Forty-second breeding bird census - Kentucky blue grass prairie Forty-second breeding bird census - Kentucky blue grass prairie
Abstract has not been submitted
Authors
Douglas H. Johnson
Effects of a summer storm on bird populations Effects of a summer storm on bird populations
Abstract has not been submitted
Authors
Douglas H. Johnson
Modeling sandhill crane population dynamics Modeling sandhill crane population dynamics
No abstract available.
Authors
Douglas H. Johnson
Estimating nest success: The Mayfield method and an alternative Estimating nest success: The Mayfield method and an alternative
Mayfield's method for calculating the success of a group of nests is examined in detail. The standard error of his estimator is developed. Mayfield's assumption that destroyed nests are at risk until the midpoint of the interval between visits leads to bias if nests are visited infrequently. A remedy is suggested, the Mayfield-40% method. I also present a competing model, which...
Authors
Douglas H. Johnson
Interpreting the results of nesting studies Interpreting the results of nesting studies
Nesting studies are used to assess the production of birds and to evaluate nesting habitats. Most such studies involve finding nests in a given area and subsequently determining the proportion that hatched. Unfortunately, the results are often biased by unrecognized differences in the probabilities of finding successful and unsuccessful nests. The observed hatch rates of 1,900 nests of...
Authors
H.W. Miller, Douglas H. Johnson
Breeding bird populations of selected grasslands in east central North Dakota -- 1977 - Kentucky blue grass prairie and mixed prairie I-V, VIII Breeding bird populations of selected grasslands in east central North Dakota -- 1977 - Kentucky blue grass prairie and mixed prairie I-V, VIII
Abstract has not been submitted
Authors
Douglas H. Johnson
Some Bayesian statistical techniques useful in estimating frequency and density Some Bayesian statistical techniques useful in estimating frequency and density
This paper presents some elementary applications of Bayesian statistics to problems faced by wildlife biologists. Bayesian confidence limits for frequency of occurrence are shown to be generally superior to classical confidence limits. Population density can be estimated from frequency data if the species is sparsely distributed relative to the size of the sample plot. For other...
Authors
Douglas H. Johnson