02/11/2002 Council Packet - Laserfiche WebLink

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• Table 1. Distribution of flights by rookery and species during 1998. Rookery Number of birds followed Number of flights Dates flown Great blue Great Egret heron Pigs Eye 11 -- a 2 April 5 - April 14 Vermillion River 46 --- a ' April 5 r April 14 Peltier Lake 63 27 7 May 1 - June 15 Smith Slough 69 59 8 April 28 - July 26 a few or no great egrets were present in the rookery 3 The habitats selected for feeding varied by rookery and species (Table 2). At Peltier Lake rookery, great blue herons selected lakes for feeding (76% of observations), whereas, great egrets selected smaller ponds (65% of feeding sites). The selection of lakes by great blue herons and ponds and marshes by great egrets at the Peltier Lake rookery was a novel result. This might be one way that herons and egrets divide up the feeding habitat. Less than 5% of feeding sites for either species were on rivers or creeks. At the Smith Slough rookery on the upper Mississippi River, however, both great blue herons and great egrets selected river and creek habitat for feeding, 90% and 84 %, for the 2 species respectively (Table 2). Fewer than 10% fed in lakes or ponds. This difference in feeding habitat use, between the 2 rookeries, is probably due to the availability of habitats. The Smith Slough rookery, being located on the upper Mississippi River, had more river habitat in close proximity to the rookery than did the Peltier Lake rookery. Likewise nearly all of the Vermillion River feeding habitat was located on rivers and creeks. When great blue herons and great egrets fed on the upper Mississippi River, most ( >80 %) fed in backwater habitats, such as braided channels and backwater areas (Table 3). Main channel habitat was used slightly, but the open parts of the navigation pools were avoided. The pond and lake division, however, was not seen at the two Mississippi River rookeries. The predominance of river habitat as the prime feeding habitat, and the lack of large lake and pond habitat nearby might o have masked the habitat -use division that was seen at Peltier Lake. •