| Go to article | Go back to Bobolink home page. | An abstract . . .
Of the following article, which appeared in Bird Observer, Vol. 23, No. 2, p. 98-112, April 1995:
BOBOLINK PROTECTION AND MORTALITY ON
SUBURBAN CONSERVATION LANDSby Stephen F. Ells
[Photo by Marj Rines. Male Bobolink adjacent to Upper Browning Field, one of Lincoln's deferred-cut sanctuaries.]
Abstract: The use of local conservation lands for breeding by the Bobolink (Dolichonyx oryzivorus) is reviewed to examine whether current management practices benefit the Bobolink and to evaluate the potential usefulness of such lands to the conservation of this declining grassland species. In the Massachusetts suburban community studied in 1993-4, 90% of breeding territories were located on conservation land, a higher percentage than would be expected based upon acreage alone. 95% were in active hayfields or a runway overrun. The breeding fields were as small as 4.3 acres, smaller than those identified as normally suitable. Unrestricted haycropping, however, destroyed more than 80% of the breeding territories on both conservation lands and other land.
Small "deferred-cut" sanctuaries, which totaled only 9 acres and on which the cut was delayed until July 15 or later, were important; they amounted to only 4% of total hayfield acreage in town but contained more than 68% of the successful breeding territories. The observed early hatches (June 6-8) were too early to be consistent with the historical egg records for the state.
The Bobolinks made extensive use of most of the uncut breeding fields into early and mid-August, and in one field into September. This is later than reported elsewhere and suggests that a later safe-cut date and modified hayfield management should be adopted for certain conservation land. Data on the timing and rate of the hatch and fledge elsewhere are correlated to the local fledge and estimates of survival for various cutting dates are suggested.
Other grassland species benefited from the local conservation lands in 1993-4, including the first breeding in Massachusetts in twenty years by endangered Henslow's Sparrows (Ammodramus henslowii), and by breeding Eastern Meadowlarks (Sturnella magna); and by breeding activity by an endangered Sedge Wren (Cistothorus platensis).
Community response to grassland bird conservation was positive, when presented with this data. The local conservation commission quadrupled the amount of deferred-cut sanctuary, issued an agriculture-wildlife policy protective of grassland birds, and protected the nesting Henslow's Sparrows with wardens. Also, the Massachusetts Port Authority has agreed to establish in 1995 a grassland bird deferred-cut area at Hanscom Field and modify its mowing regime. The Massachusetts Audubon Society purchased additional agricultural acreage next to Drumlin Farm. And also, the Massachusetts Association of Conservation Commissions has informed commissions state-wide of these activities. These results suggest that local conservation lands and organizations could be a potentially valuable resource for the preservation of certain grassland species. [End of abstract.]
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