WADING BIRD USE OF ESTABLISHED AND NEWLY CREATED REACTOR COOLING RESERVOIRS AT THE SAVANNA-RIVER SITE, NEAR AIKEN, SOUTH-CAROLINA, USA

We compared wading bird use of a newly created 405-ha reactor cooling reservoir (L-Lake) at the Savannah River Site, near Aiken, South Carol ina, with that of two similar > 25-year-old reservoirs (1130-ha Par Po nd and 87-ha Pond B) at the same site. L-Lake was constructed in 1984- 1985 and filled in late 1985. Approximately 25% of the shoreline of L- Lake was planted with lacustrine vegetation in early 1987 in an attemp t to speed the establishment of a self-sustaining balanced biological community (BBC) at the reservoir. Even so, during the course of our st udies, L-Lake had considerably less wetland vegetation, especially flo ating-leaved species such as yellow nelumbo (Nelumbo lutea), than did either of the two older reservoirs. Sixty-three surveys of the avian c ommunities using the three reservoirs were conducted between fall of 1 987 and summer of 1989. These surveys indicated that (1) at least seve n species of wading birds (order: Ciconiiformes) used L-Lake, (2) wadi ng bird density was higher at L-Lake than at the other two reservoirs, (3) wading birds represented a higher proportion of the total avian c ommunity at L-Lake than at the other two, older reservoirs, and (4) wa ding birds at L-Lake used planted portions of the shore-line more than unplanted portions. We suggest that the inter-reservoir differences w e observed represent a 'trophic upsurge' (sensu O'Brien, 1990) resulti ng from the increased availability of fishes at L-Lake compared with t he two older reservoirs.