Birds of Indian Subcontinent

Bird Populations of Bogs

Publication Type:Journal Article
Year of Publication:1967
Authors:Brewer, R
Journal:The Wilson Bulletin
Date Published:1967
ISBN Number:00435643
Keywords:Corvidae, Cyanocitta, Cyanocitta cristata, Garrulus, Garrulus glandarius, Melospiza, Melospiza melodia, Parus, Parus atricapillus, Passerella, Passerella melodia, Pipilo, Pipilo erythrophthalmus, Piranga, Piranga olivacea, Poecile, Poecile atricapilla, Poecile atricapillus, Seiurus, Seiurus aurocapilla, Seiurus aurocapillus, Spizella, Spizella pusilla, Zonotrichia, Zonotrichia melodia
Abstract:Bird populations were studied on two bog areas in southwestern Michigan. One, a sphagnum--leatherleaf--tamarack bog, had an average of about 16 breeding species per year and an average density of about 170 males per 100 acres. Song Sparrow was by far the most abundant species; Yellowthroat, Rufous-sided Towhee, and Field Sparrow were also numerically important. All but the last showed higher densities in thicket compared with open parts of the bog. Most of the birds were forest-edge species of wide geographical range. Populations were sparse outside the breeding season, probably because of a poor food supply. The second area, a yellow birch--red maple--white pine bog forest, had about 20 breeding species a year. Density was about 270 males per 100 acres. Black-capped Chickadee, Ovenbird, Wood Pewee, Blue Jay, Cardinal, Scarlet Tanager, and four other species had densities greater than 10 per 100 acres. Between 1965 and 1966, the number of Ovenbirds greatly increased and Song Sparrows greatly declined. Two ways of viewing bog bird communities are set forth. The first, classificatory or organismic, recognizes four main ecological groups of birds occurring in bogs (marsh, thicket or forest edge, spruce--fir forest, and deciduous forest), while acknowledging that any given stand may contain elements of more than one group. The second, individualistic, view emphasizes the tendency for each species to be distributed accordingly as it encounters suitable habitat within its range of geographic occurrence. The second view is essentially correct for the instantaneous description of a stand, but it seems not to give sufficient weight to historical and evolutionary factors. The concept of bogs as boreal islands is valid for a certain range of latitudes. North of this, bogs are not much more boreal than surrounding vegetation and southward the number of boreal species rapidly diminishes until in southwestern Michigan there is practically no boreal character to the bird population.
Short Title:The Wilson Bulletin
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