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Proximate And Landscape Factors Influence Grassland Bird Distributions, Mary Ann Cunningham, Douglas H. Johnson
Proximate And Landscape Factors Influence Grassland Bird Distributions, Mary Ann Cunningham, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
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 high conservation concern, in the Sheyenne National Grassland in North Dakota, USA. The Grassland contains a diverse array of grassland and woodland habitats. We surveyed breeding birds on 2015 100 m long transect segments during 2002 and 2003. We modeled …
Influences Of Management Regimes On Breeding Bird Densities And Habitat In Mixed-Grass Prairie: An Example From North Dakota, Andrea A. Lueders, Patricia L. Kennedy, Douglas H. Johnson
Influences Of Management Regimes On Breeding Bird Densities And Habitat In Mixed-Grass Prairie: An Example From North Dakota, Andrea A. Lueders, Patricia L. Kennedy, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
It is well known that North American grassland bird populations appear to be declining (Igl and Johnson 1997, Sauer et al. 2004). Most of these birds breed and winter in North America, so declines are likely associated with continental processes (Knopf 1994). Scientists have also observed parallel declines among species that have overlapping breeding ranges but disparate wintering distributions (Igl and Johnson 1997). These patterns suggest declines may be linked to problems on the breeding grounds.
Avian Response To Meadow Restoration In The Central Great Plains, Rosalind B. Renfrew, Douglas H. Johnson, Gary R. Lingle, W. Douglas Robinson
Avian Response To Meadow Restoration In The Central Great Plains, Rosalind B. Renfrew, Douglas H. Johnson, Gary R. Lingle, W. Douglas Robinson
USGS Northern Prairie Wildlife Research Center
Native grassland is one of the most heavily degraded of all North American ecosystems, and restoration of altered grasslands is a tool used to mitigate some of the biological ramifications of past land use practices. Providing habitat for grassland-dependent bird species often is one of the many goals of restoration. We evaluated the efficacy of meadow restoration for breeding birds in the Nebraska Platte River Valley by comparing the bird community and vegetation structure on 25 natural (original sod) and 25 restored meadows. We conducted principal components analyses on the vegetation structure and on the bird community, and modeled the …
A Historical Perspective: Changes In Grassland Breeding Bird Densities Within Major Habitats In North Dakota Between 1967 And 1992-1993, Lawrence D. Igl, Douglas H. Johnson, Harold A. Kantrud
A Historical Perspective: Changes In Grassland Breeding Bird Densities Within Major Habitats In North Dakota Between 1967 And 1992-1993, Lawrence D. Igl, Douglas H. Johnson, Harold A. Kantrud
USGS Northern Prairie Wildlife Research Center
Population declines of many grassland-nesting birds are now widely recognized. Fundamental to understanding these declines is knowing if they are caused by changes in the availability of suitable habitats or changes in the densities of birds within those habitats. We address that issue with information from systematic surveys of breeding birds throughout North Dakota in 1967, 1992, and 1993. We compared the availability of 8 major habitat types, and the densities of 24 species of grassland birds in each habitat type, for 128 randomly selected quarter-sections (64.7 ha or 160 ac) that were surveyed in each of those years. Between …