Native Plants As Habitat For Wildlife - Native Plant Society of ...

In the first study widespread loss of Elm trees to Dutch Elm Disease appears to have
resulted in a decline of Eastern Screech Owls along the lower Souris River. Two
comprehensive surveys have been conducted along this stretch of the river, the first was
conducted in the spring of 1986 the second in the spring of 1997. Fifteen calling birds
were found along the river in 1986, whereas only four calling birds were heard calling in
1997. The decline of the Screech-owl may have been be exacerbated by competition with
increasing number of Fox Squirrels in the area. Fox Squirrels actively compete with other
wildlife including Screech-owls for nesting and roosting sites. The provision of nest
boxes may, however, help reverse the trend in Screech-Owl populations in the area.
In the other study area bird were surveyed on 36 point counts distributed between the
Alberta border and the old Prelate Ferry northeast of Leader. Sample sizes were too small
to yield statistically significant results for some of the parameters studied, but were
sufficient to determine the effects of moderate grazing on the avifaunal composition.
Three of the fifteen most common species, the American Robin, Spotted Towhee and
Western Meadowlark, were significantly more common on grazed than on ungrazed point
counts. On the other hand, no species were found to be negatively affected by moderate
grazing.
The results of this study were, for the American Robin, consistent with the majority of
nine studies of the effects of cattle grazing in the western United States as reviewed by
Saab et al. (1995). Spotted Towhees may have been more abundant on grazed plots
because moderate grazing promotes the growth of shrubbery by reducing competition for
water and nutrients by grasses (Nernberg, pers. Comm., 1999). Meadowlarks are
presumably rarer on ungrazed plots because the grassland areas are often cultivated.
Anstey et al. (1995) found meadowlarks at less than one fifth the density in cropland
compared to native prairie.
The second study suggests that, in the short term, moderate grazing has no adverse effects
on bird populations in the Leader area. Longer more intensive studies are, however,
needed to determine the effects of more intensive grazing on the flora and fauna, as well
as the potential effects of even moderate grazing on the regeneration of woodlands in the
area.
Literature Cited
Anstey, D. A., S. K. Davis, D. C. Duncan and M. Skeel. 1995. Distribution and habitat
selection of eight grassland songbird species in southern Saskatchewan.
Saskatchewan Wetland Conservation Corporation, Regina. 11pp. + Tables.
Bradley, C. 1982. Modified meandering river regimes-Effects on plains cottonwood
regeneration, Milk River Valley, S. E. Alberta, and N. Montana. M. S. Thesis, Dep.
of Geog., Univ. of Calgary, Alta.
Gregory, S. V., F. J. Swanson, W. A. McKee, and K. W. Cummins. 1991. An ecosystem
perspective of riparian zones. Bioscience 41:540-551.
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