SOUTH FLORIDA WADING BIRD REPORT Volume 12 Mark I. Cook and Erynn M. Call, Editors October 2006 were conducted at Lake Okeechobee (last year, a single count SYSTEM-WIDE SUMMARY was conducted in June). As with other South Florida wetland systems, the lake and surrounding marshes exhibited a consistent Total rainfall for water year 2006 was close to average but a very and timely drydown throughout the nesting season and nest wet June ‘05 and consistent rainfall through October ‘05 numbers were the highest recorded in over 30 years. The total produced above average water levels over most areas until the number of nests at Lake Okeechobee and Kissimmee in 2006 onset of the dry season. Tropical Storm Katrina and Hurricane was 11,447, which demonstrates the continued importance of Wilma were not major rain events and failed to have a significant these regions to South Florida wading birds. (Note that this total impact on stage. Subsequent below average rainfall from is not included in the system wide total.) November ‘05 to July ‘06 led to generally ‘good’ water recession rates and provided suitable foraging conditions over large areas This year’s large nesting effort occurred for the majority of of the system for much of the breeding season. species but the most noteworthy increases were for Snowy Egrets and Wood Storks. This is encouraging because these The estimated number of wading bird nests in South Florida in species have not enjoyed the general increase in nesting effort 2006 was 54,634 (excluding Cattle Egrets, which are not exhibited by some other wading bird species in recent years. dependent on wetlands). This is a large increase in nest numbers Number of Tricolor Heron nests, however, declined relative to compared to last year (71%), and only 20% less than the banner last year (down 44%) and continue to show the steady decline year of 2002 (68,750 nests). Note that this year’s total is likely a exhibited since 2001. Number of Roseate Spoonbill nests in conservative estimate. Surveys were not conducted this year at J. Florida Bay was also slightly down on average. N. ‘Ding’ Darling National Wildlife Refuge Complex, which usually adds approx. 1000-2000 nests to the system total. More Locations of wading bird colonies with ≥ 50 nests in South significantly, ground survey coverage for the WCAs was Florida, 2006. relatively limited this year and may underestimate the count for this area by up to 30% (see Simon et al., this issue). Adjusting for this underestimate increases the total number of nests in South Florida to approximately 70,000. Irrespective of how the total is estimated, 2006 represents a successful year for wading birds in terms of overall nest numbers and is comparable to historic nesting events in the 1940s. In recent years, systematic nest survey coverage has been expanded to include the Kissimmee River floodplain and Lake Okeechobee. The Kissimmee River floodplain and surrounding wetlands supported large numbers of wading birds in 2006. Phase 1 of the Kissimmee restoration project was completed in 2001, and numbers of foraging wading birds continue to increase annually. This year’s total was the highest recorded to date. 2006 was the first year since 1992 that systematic monthly nest counts INSIDE THIS ISSUE 3 Hydrology 2006 5 Regional Nesting Reports 32 Regional Bird Abundance 38 Population Recovery Status 2006 40 Special Topics Wading Bird Report 1 For all species, nesting success was generally high relative to not fully explain foraging and nesting patterns. Hydrologic recent years and the post-fledging environment was conducive conditions in February this year were similar to those reported in to optimal foraging and high fledgling survival rates. 2005, yet numbers of foraging wading birds in the WCAs in February this year were only half those of February 2005. This As usual for recent years, nesting effort in the Everglades was suggests that factors independent of recession rates and water not uniformly distributed among regions. WCA-3 supported the depth such as the total prey available or foraging conditions largest number of nests (58%), whereas WCA-1 (21%) and ENP beyond the Everglades may play a significant role in wading bird (21%) supported a similar nesting effort. Increasing the foraging decisions in South Florida. This observation also begs proportion of nests in ENP is a goal of CERP restoration the question as to why numbers of pre-breeding foraging efforts, and it is notable that ENP contributed considerably individuals do not relate directly to number of nests. The more nests in 2006 than it has done in recent years. It is also relatively low breeding effort in 2005 may be explained partly by encouraging to note that this is the third successive season in the reversal events in March 2005 which undoubtedly limited the which nesting has occurred and increased at the traditional number of nests of later breeding species such as White Ibis “rookeries” in the southern, mainland estuaries downstream which do not breed until late March. It does not, however, from Shark Slough. Indeed, these colonies contained explain why the number of nests of earlier nesting species, such approximately half the number of nests in ENP and 10% of as Wood Stork and Great Egret, were lower in 2005 than they total nests in the Everglades. The reasons for this are not clear were in 2006. Finally, if environmental conditions this year were at present but relative increases in the number of birds feeding highly favorable for White Ibis and Wood Stork, why were they along the coastal margins of ENP suggest that foraging not suitable for Tricolor Herons? conditions in the estuaries have improved. A trend in recent years has been for a large proportion of nests in South Florida to The contributors to this Report are largely responsible for be concentrated in a single large colony (Alley North) located in answering these and other critical questions. At the conception northeast WCA-3A. While the 2006 breeding season followed a of the wading bird report in 1994 the contributors had the similar pattern, with 31% of all nests found in Alley North, the foresight to recognize that restoration requires a multi-agency disparity was reduced relative to 2005 (57%) and 2004 (40%). approach that crosses jurisdictional boundaries and encompasses a system-wide assessment of wading bird ecology. Twelve years Systematic Reconnaissance Flight surveys (SRF) show that the later this recognition, along with a free flow of information, have temporal distribution of wading birds in 2006 differed from that led to considerable improvements in our understanding of of 2005. Last year record numbers of birds frequented the wading bird reproductive ecology and to some extent in our system from January through March, but numbers declined capacity to effectively manage the system. Indeed, during the dramatically thereafter. This year overall bird abundance was past decade we have witnessed a rise in the reproductive effort consistently high from January through June. The system-wide of a number of species, and this may be attributed, at least partly, total wading bird abundance in 2006 was higher than that of to increased input from ecologists into water management 2005. decisions. The road to a restored Everglades will be a long and challenging one but there is certainly cause for optimism. The Two of four species-groups (White Ibis and Great Egret) met contributors have laid the foundation for wading bird restoration the numeric nesting targets proposed by the South Florida and with continued dedication to good science and effective Ecosystem Restoration Task Force. Two other targets for the communication there remains hope that we can further restore Everglades restoration are an increase in the number of nesting and sustain South Florida’s wading bird populations. wading birds in the coastal Everglades and a shift in the timing of Wood Stork nesting to earlier in the breeding season (Ogden, Mark I. Cook and Erynn M. Call 1997). The 2006 nesting year showed no improvement in the Everglades Division, South Florida Water Management District, 3301 timing of Wood Stork nesting but there was a general shift of Gun Club Road, West Palm Beach, FL 33406; 561-686-8800 ext. colony locations. 4539; [email protected], [email protected] Examining the annual breeding response of wading birds improves our understanding of how the Everglades and other South Florida ecosystems function. This year, at least some of the increased nesting effort and success may be attributed to favorable hydrologic and climatic conditions. The wet season prior to breeding was longer and wetter than average, which is considered to be favorable for aquatic prey production. Dry- season water depths and recession rates were classified as ‘good’ for wading birds and provided suitable foraging conditions throughout the system for much of the breeding season. Rainfall and reversal events were limited in frequency and magnitude, and induced only minimum nest failure. This pattern contrasts with that of 2005, when multiple heavy rain events through March and April resulted in a succession of reversals that left protracted high water levels, and thus poor foraging condition over much of the system. Hydrologic conditions, however, do Wading Bird Report 2 HYDROLOGY 2006 WCA-1 The amount of rain in water-year 2006 (May 2005 – April 2006) Last year, during the critical wading bird foraging and nesting was 11-12 inches greater than last year. The rainfall and period of March – April, dramatic reversals occurred and rainfall associated stage readings for the 2006 water-year are shown in increased depths up to 1.5 ft. Despite the March ‘05 reversals, Table 1 below. Most of the rain fell during the month of June WCA-1 had the longest duration of good nesting and foraging 2005.