Douglas Johnson (Former Employee)
Science and Products
Filter Total Items: 318
Area sensitivity in North American grassland birds: Patterns and processes Area sensitivity in North American grassland birds: Patterns and processes
Grassland birds have declined more than other bird groups in North America in the past 35-40 years (Vickery and Herkert 2001, Sauer et al. 2008), prompting a wide variety of research aimed at understanding these declines, as well as conservation programs trying to reverse the declines (Askins et al. 2007). Area sensitivity, whereby the pattern of a species’ occurrence and density...
Authors
C. A. Ribic, Rolf R. Koford, J.R. Herkert, Douglas H. Johnson, N.D. Niemuth, D.E. Naugle, Kristel K. Bakker, D. W. Sample, R.B. Renfrew
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
A review of the population estimation approach of the North American landbird conservation plan A review of the population estimation approach of the North American landbird conservation plan
As part of their development of a continental plan for monitoring landbirds (Rich et al. 2004), Partners in Flight (PIF) applied a new method to make preliminary estimates of population size for all 448 species of landbirds present in the continental United States and Canada (Table 1). Estimation of the global population size of North American landbirds was intended to (1) identify the...
Authors
Wayne E. Thogmartin, Frank P. Howe, Frances C. James, Douglas H. Johnson, Eric T. Reed, John R. Sauer, Frank R. Thompson
Patch size and landscape effects on density and nesting success of grassland birds Patch size and landscape effects on density and nesting success of grassland birds
Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires...
Authors
Maiken Winter, Douglas H. Johnson, Jill A. Shaffer, Therese M. Donovan, W. Daniel Svedarsky
Proximate and landscape factors influence grassland bird distributions Proximate and landscape factors influence grassland bird distributions
Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of...
Authors
M.A. Cunningham, Douglas H. Johnson
Conspecific attraction in a grassland bird, the Baird's Sparrow Conspecific attraction in a grassland bird, the Baird's Sparrow
Territorial songbirds generally use song to defend territories and attract mates, but conspecific song may also serve as a cue to attract other male songbirds to a breeding site. Although known to occur in some colonial and forest-associated species, only recently have investigators examined conspecific attraction in grassland species. We used a playback experiment to examine the...
Authors
M.A. Ahlering, Douglas H. Johnson, John Faaborg
Does body size affect a bird's sensitivity to patch size and landscape structure? Does body size affect a bird's sensitivity to patch size and landscape structure?
Larger birds are generally more strongly affected by habitat loss and fragmentation than are smaller ones because they require more resources and thus larger habitat patches. Consequently, conservation actions often favor the creation or protection of larger over smaller patches. However, in grassland systems the boundaries between a patch and the surrounding landscape, and thus the...
Authors
Maiken Winter, Douglas H. Johnson, Jill A. Shaffer
A fresh look at the taxonomy of midcontinental sandhill cranes A fresh look at the taxonomy of midcontinental sandhill cranes
The midcontinental population of sandhill crane (Grus canadensis) includes about 500,000 birds and provides valuable recreational crane-watching and hunting opportunities in Canada and the United States. It comprises three subspecies, one of which (G. c. rowani) was of uncertain taxonomic status and another of which (G. c. tabida) merited protection from excessive harvest due to its...
Authors
Douglas H. Johnson, Jane E. Austin, Jill A. Shaffer
Science and Products
Filter Total Items: 318
Area sensitivity in North American grassland birds: Patterns and processes Area sensitivity in North American grassland birds: Patterns and processes
Grassland birds have declined more than other bird groups in North America in the past 35-40 years (Vickery and Herkert 2001, Sauer et al. 2008), prompting a wide variety of research aimed at understanding these declines, as well as conservation programs trying to reverse the declines (Askins et al. 2007). Area sensitivity, whereby the pattern of a species’ occurrence and density...
Authors
C. A. Ribic, Rolf R. Koford, J.R. Herkert, Douglas H. Johnson, N.D. Niemuth, D.E. Naugle, Kristel K. Bakker, D. W. Sample, R.B. Renfrew
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
A review of the population estimation approach of the North American landbird conservation plan A review of the population estimation approach of the North American landbird conservation plan
As part of their development of a continental plan for monitoring landbirds (Rich et al. 2004), Partners in Flight (PIF) applied a new method to make preliminary estimates of population size for all 448 species of landbirds present in the continental United States and Canada (Table 1). Estimation of the global population size of North American landbirds was intended to (1) identify the...
Authors
Wayne E. Thogmartin, Frank P. Howe, Frances C. James, Douglas H. Johnson, Eric T. Reed, John R. Sauer, Frank R. Thompson
Patch size and landscape effects on density and nesting success of grassland birds Patch size and landscape effects on density and nesting success of grassland birds
Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires...
Authors
Maiken Winter, Douglas H. Johnson, Jill A. Shaffer, Therese M. Donovan, W. Daniel Svedarsky
Proximate and landscape factors influence grassland bird distributions Proximate and landscape factors influence grassland bird distributions
Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of...
Authors
M.A. Cunningham, Douglas H. Johnson
Conspecific attraction in a grassland bird, the Baird's Sparrow Conspecific attraction in a grassland bird, the Baird's Sparrow
Territorial songbirds generally use song to defend territories and attract mates, but conspecific song may also serve as a cue to attract other male songbirds to a breeding site. Although known to occur in some colonial and forest-associated species, only recently have investigators examined conspecific attraction in grassland species. We used a playback experiment to examine the...
Authors
M.A. Ahlering, Douglas H. Johnson, John Faaborg
Does body size affect a bird's sensitivity to patch size and landscape structure? Does body size affect a bird's sensitivity to patch size and landscape structure?
Larger birds are generally more strongly affected by habitat loss and fragmentation than are smaller ones because they require more resources and thus larger habitat patches. Consequently, conservation actions often favor the creation or protection of larger over smaller patches. However, in grassland systems the boundaries between a patch and the surrounding landscape, and thus the...
Authors
Maiken Winter, Douglas H. Johnson, Jill A. Shaffer
A fresh look at the taxonomy of midcontinental sandhill cranes A fresh look at the taxonomy of midcontinental sandhill cranes
The midcontinental population of sandhill crane (Grus canadensis) includes about 500,000 birds and provides valuable recreational crane-watching and hunting opportunities in Canada and the United States. It comprises three subspecies, one of which (G. c. rowani) was of uncertain taxonomic status and another of which (G. c. tabida) merited protection from excessive harvest due to its...
Authors
Douglas H. Johnson, Jane E. Austin, Jill A. Shaffer