Douglas Johnson (Former Employee)
Science and Products
Filter Total Items: 318
Feeding ecology of arctic-nesting sandpipers during spring migration through the prairie pothole region Feeding ecology of arctic-nesting sandpipers during spring migration through the prairie pothole region
We evaluated food habits of 4 species of spring-migrant calidrid sandpipers in the Prairie Pothole Region (PPR) of North Dakota. Sandpipers foraged in several wetland classes and fed primarily on aquatic dipterans, mostly larvae, and the midge family Chironomidae was the primary food eaten. Larger sandpiper species foraged in deeper water and took larger larvae than did smaller...
Authors
J.L. Eldridge, Gary L. Krapu, Douglas H. Johnson
Countability of sandhill cranes in aerial surveys Countability of sandhill cranes in aerial surveys
No abstract available.
Authors
Douglas H. Johnson, W John Solberg, Courtney L. Amundson
Ways of learning: Observational studies versus experiments Ways of learning: Observational studies versus experiments
Manipulative experimentation that features random assignment of treatments, replication, and controls is an effective way to determine causal relationships. Wildlife ecologists, however, often must take a more passive approach to investigating causality. Their observational studies lack one or more of the 3 cornerstones of experimentation: controls, randomization, and replication...
Authors
T.L. Shaffer, Douglas H. Johnson
Tower counts Tower counts
Counting towers provide an accurate, low-cost, low-maintenance, low-technology, and easily mobilized escapement estimation program compared to other methods (e.g., weirs, hydroacoustics, mark-recapture, and aerial surveys) (Thompson 1962; Siebel 1967; Cousens et al. 1982; Symons and Waldichuk 1984; Anderson 2000; Alaska Department of Fish and Game 2003). Counting tower data has been...
Authors
Carol Ann Woody
Brown-headed cowbird, Molothrus ater, parasitism and abundance in the northern Great Plains Brown-headed cowbird, Molothrus ater, parasitism and abundance in the northern Great Plains
The Brown-headed Cowbird (Molothrus ater) reaches its highest abundance in the northern Great Plains, but much of our understanding of cowbird ecology and host-parasite interactions comes from areas outside of this region. We examine cowbird brood parasitism and densities during two studies of breeding birds in the northern Great Plains during 1990–2006. We found 2649 active nests of 75...
Authors
L.D. Igl, Douglas H. Johnson
Scaling-up of CO2 fluxes to assess carbon sequestration in rangelands of Central Asia Scaling-up of CO2 fluxes to assess carbon sequestration in rangelands of Central Asia
Flux towers provide temporal quantification of local carbon dynamics at specific sites. The number and distribution of flux towers, however, are generally inadequate to quantify carbon fluxes across a landscape or ecoregion. Thus, scaling up of flux tower measurements through use of algorithms developed from remote sensing and GIS data is needed for spatial extrapolation of carbon fluxes...
Authors
Bruce K. Wylie, Tagir G. Gilmanov, Douglas A. Johnson, Nicanor Z. Saliendra, Larry L. Tieszen, Ruth Anne F. Doyle, Emilio Laca
Science and Products
Filter Total Items: 318
Feeding ecology of arctic-nesting sandpipers during spring migration through the prairie pothole region Feeding ecology of arctic-nesting sandpipers during spring migration through the prairie pothole region
We evaluated food habits of 4 species of spring-migrant calidrid sandpipers in the Prairie Pothole Region (PPR) of North Dakota. Sandpipers foraged in several wetland classes and fed primarily on aquatic dipterans, mostly larvae, and the midge family Chironomidae was the primary food eaten. Larger sandpiper species foraged in deeper water and took larger larvae than did smaller...
Authors
J.L. Eldridge, Gary L. Krapu, Douglas H. Johnson
Countability of sandhill cranes in aerial surveys Countability of sandhill cranes in aerial surveys
No abstract available.
Authors
Douglas H. Johnson, W John Solberg, Courtney L. Amundson
Ways of learning: Observational studies versus experiments Ways of learning: Observational studies versus experiments
Manipulative experimentation that features random assignment of treatments, replication, and controls is an effective way to determine causal relationships. Wildlife ecologists, however, often must take a more passive approach to investigating causality. Their observational studies lack one or more of the 3 cornerstones of experimentation: controls, randomization, and replication...
Authors
T.L. Shaffer, Douglas H. Johnson
Tower counts Tower counts
Counting towers provide an accurate, low-cost, low-maintenance, low-technology, and easily mobilized escapement estimation program compared to other methods (e.g., weirs, hydroacoustics, mark-recapture, and aerial surveys) (Thompson 1962; Siebel 1967; Cousens et al. 1982; Symons and Waldichuk 1984; Anderson 2000; Alaska Department of Fish and Game 2003). Counting tower data has been...
Authors
Carol Ann Woody
Brown-headed cowbird, Molothrus ater, parasitism and abundance in the northern Great Plains Brown-headed cowbird, Molothrus ater, parasitism and abundance in the northern Great Plains
The Brown-headed Cowbird (Molothrus ater) reaches its highest abundance in the northern Great Plains, but much of our understanding of cowbird ecology and host-parasite interactions comes from areas outside of this region. We examine cowbird brood parasitism and densities during two studies of breeding birds in the northern Great Plains during 1990–2006. We found 2649 active nests of 75...
Authors
L.D. Igl, Douglas H. Johnson
Scaling-up of CO2 fluxes to assess carbon sequestration in rangelands of Central Asia Scaling-up of CO2 fluxes to assess carbon sequestration in rangelands of Central Asia
Flux towers provide temporal quantification of local carbon dynamics at specific sites. The number and distribution of flux towers, however, are generally inadequate to quantify carbon fluxes across a landscape or ecoregion. Thus, scaling up of flux tower measurements through use of algorithms developed from remote sensing and GIS data is needed for spatial extrapolation of carbon fluxes...
Authors
Bruce K. Wylie, Tagir G. Gilmanov, Douglas A. Johnson, Nicanor Z. Saliendra, Larry L. Tieszen, Ruth Anne F. Doyle, Emilio Laca