publications > open file report > OFR 2006-1126 > methods
Wildlife and habitat damage assessment from Hurricane Charley: recommendations for recovery of the J. N. Ding Darling National Wildlife Refuge Complex
Hurricane Charley storm development and physical characteristics.
Descriptions of Hurricane Charley's development, storm path, and physical characteristics were drawn from reports and preliminary data primarily published on the internet. Many reputable sources of information, such as NOAA's National Hurricane Center (NHC), made preliminary data and analyses available as soon as possible to the public for research and information purposes. Analyses and reports presented here should be viewed as preliminary and subject to change as agencies and institutions finalize and publish their research after the hurricane season. Electronic copies of the information from web sites or unpublished reports are available from C.A. Langtimm.
Habitat damage and bird surveys
We conducted field surveys of selected major habitats of JNDDNWR and the islands of Matlachee Pass and Pine Island NWR's (Fig. 3 and 4), two of largest of the satellite refuges, from 20 to 24 September 2004. The islands surveyed provide habitat for large numbers of nesting waterbirds from late February to July each year, but also provide resting habitat within close proximity to foraging sites during other times of the year. At each island or habitat, we collected data on trees using standard techniques for describing hurricane damage (see Vegetation below) (Smith and others, 1994 Walker, 1991). We collected a GPS position (UTM and LAT-LONG coordinates, NAD83) of the survey and photographed habitat at 2 to 6 recorded bearings (ca. 45° to 180° intervals). We also took an overstory photograph for estimating cover at the same point. These photographs not only provide information on damage, but will allow estimation of damage over a much larger area using visual and other photogrammetric comparisons (i.e., locations can be found on aerial photographs with GPS data). Birds were noted and photographed when encountered; we counted endangered Wood Storks and nesting ibises and herons. Presence of exotic plants was also recorded and the plants were photographed. We sampled and photographed a total of 35 locations in 15 habitats or islands, totaling 168 photographs with GPS in UTM (NAD83) coordinates and bearings in degrees (Table 1). Islands were sampled on the fringe and also at an interior location. Bird nomenclature follows the American Ornithologists' Union (1998).
We used several sources of data to document and describe important manatee habitat areas in and near the refuge complex prior to landfall of Hurricane Charley. General descriptions of manatee distribution patterns in the refuge complex were drawn from regional data, analyses, and figures provided by the Fish and Wildlife Research Institute (FWRI) of the Florida Fish and Wildlife Conservation Commission (Sara McDonald, personal communication). Aerial survey data were collected by FWRI in Lee County during twice monthly surveys in 1994-1995 and 1997-1998. Data were analyzed by applying a variable-shape spatial filter to make a contour map of manatee abundance, as described in Flamm and others, (2001). Warm and cold season distribution and relative abundance maps were developed for Estero Bay, Matlacha Pass (including Tarpon and San Carlos Bays) and Pine Island Sound. Two of these regions, Matlacha Pass and Pine Island Sound encompass the landscape administered by the refuge complex.
Movement of individual manatees in these two regions was also monitored by FWRI with satellite telemetry. Tracking was limited to the cold season. Location data were analyzed and maps developed delineating manatee corridors used by animals to travel from one area to another, and manatee places indicative of important habitat where individuals spend extended periods of time. Data from 16 animals tracked in Matlacha Pass and 12 animals tracked in Pine Island Sound are presented in this report in figures provided by FWRI.
Information on cold season thermal refuges nearest the refuge complex was provided by Mote Marine Laboratory and FWRI, the partners collaborating with USGS Sirenia Project on the Manatee Individual Photo-identification System (MIPS). This program provides state-wide monitoring of manatees through photo-documentation of known individuals at the major winter aggregation sites.
The distribution of seagrass was drawn from regional monitoring and assessment programs, provided by FWRI and as reported by Dawes and others (2004). An assessment of the degree of scarring of these beds by boat propellers was based on a technical report published by FMRI (Madley and others, 2004).
Data are few on the direct impact of the hurricane on manatees and manatee habitat. Observations of damage to seagrass beds during aerial surveys by refuge personnel and monitoring by Mote Marine Lab are described. We further identify those areas in the refuge complex with the greatest likelihood of impact by comparing the path of the core of the storm with pre-hurricane distributions of primary habitat and manatee high use areas. We then project possible short-term and long-term impacts to habitat and manatees based on principles of biology and findings from previous research at other locations.
Historical characteristics of the Sanibel regional landscape
After our field surveys, we acquired historical topographic sheets for the Sanibel - Captiva - Pine Island area, which were prepared by the United States Coast and Geodetic Survey from 1857-1867. These sheets are not rectified or geo-referenced at this time. Some features, however, are visible on the 19th Century sheets, when compared with the same areas on recent false color infrared aerial photographs (1999). Specifically, we determined if the rookery islands of interest to refuge staff were present on the historic sheets and we compared other specific areas of interest, such as the Shell Mound Trail area.
We conducted qualitative (visual) and quantitative vegetation surveys in a variety of habitats at 15 areas of JNDDNWR Complex. Mangrove forests comprise the majority of forested habitat on the Complex; therefore, more surveys were conducted in these forests. We surveyed and sampled mangrove forests at Shell Mound Trail, Power Line easement (road), Legion Curve, Givney Key, Upper and Lower Bird Islands, Bird Key, Hemp Island, Lumpkin Island, East and West Impoundments, and along Dixie-Beach Boulevard (see Figs. 3, 4, and 5 for island and study locations). Hardwood hammocks were examined at Shell Mound (Fig. 5), along the Legion Curve (west side of Indigo Trail) and at Hemp Island (Fig. 4). We recorded damage and mortality (by species), size (diameter at breast height [dbh] in cm) and direction of fall in plots of known area at several locations. No stems were permanently tagged for future reference although the locations of the plot were recorded in latitude-longitude (degrees to 5 decimal places) and UTM (NAD83) using GPS. In addition, we surveyed four mangrove forest plots (vegetation) that had been established by the Sanibel-Captiva Conservation Foundation Marine Laboratory (SCCF) prior to the passage of Hurricane Charley (plots 5 and 6, near JNDDNWR's West Impoundment and plots 7 and 8, along Dixie-Beach Boulevard).
We made observations concerning the potential for vegetation communities to recover. This included noting the presence or absence of seedlings and/or sapling-sized individuals at all sites. We examined damaged individuals to see if they were coppicing or stump sprouting (the production of adventitious shoots from the main trunk or stump). Special attention was given to vines and lianas, both native and exotic, as they can respond to disturbance very quickly.
Following our field work at JNDDNWR Complex we conducted literature searches to compile lists of potential invasive exotic species which could become of management concern in the future. Botanical nomenclature follows Nelson (1996) and Wunderlin (1998).
U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 15 January, 2013 @ 12:43 PM(TJE)