|WI - Cormorant Research Group Study||Scientific Literature||Double-crested cormorant|
Belant J.L., L.A. Tyson & Mastrangelo P.A. 2000.
Effects of lethal control at aquaculture facilities on populations of piscivorous birds.
Wildlife Society Bulletin, 28(2): 379 - 384.
ABSTRACT - We used depredation permit records to document the extent of lethal control at aquaculture facilities in a 9-state region of the southeastern United States from 1987 to 1995, and used Christmas Bird Count (CBC) data (1987-1995) to evaluate the effects of this program on winter populations of piscivorous birds. During these 9 years, 904 depredation permits (including 21 species) were issued, primarily for double-crested cormorants (Phalacrocorax auritus) (94% of permits issued), great blue herons (Ardea herodias) (80%), and great egrets (Ardea alba) (60%). For all species and years, 108,701 bir ds were authorized to be taken; of these, 64,011(59%) were reported taken, primarily double-crested cormorants (55%), great blue herons (21%), and gre at egrets (13%). Most (74-78%) of these species were taken in Arkansas. Ove rall, actual take did not exceed 65% of the authorized take for any species . For stales where double-crested cormorants, great blue herons, or great e grets were taken, there was no negative association (r greater than or equal to- 0.42, P greater than or equal to 0.26) between number of birds taken annually and the respective mean number of birds observed/CBC that same year. Also, number of these species taken annually represented <3% of the resp ective continental breeding populations. We conclude that number of double-crested cormorants, great blue herons, and great egrets taken with depredation permits at aquaculture facilities in the southeastern United States did not adversely affect regional winter or continental breeding populations o f these species.
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