Annual Assessment Update

Transcription

1 2011 Annual Assessment Update Comprehensive Everglades Restoration Plan (CERP): American Alligator Density, Size, and Hole Occupancy and American Crocodile Juvenile Growth & Survival MAP Activities and (Greater Everglades Wetlands Module) Prepared by: Brian M. Jeffery 1 and Michael S. Cherkiss 2 Edited by: Kristen M. Hart 2 Frank J. Mazzotti 1 and Laura A. Brandt 3 Prepared for: U.S. Army Corps of Engineers (University of Florida, Fort Lauderdale Research and Education Center) 2 (USGS, Florida Integrated Science Center) 3 (USFWS)

2 Acknowledgements We thank the U.S. Army Corps of Engineers for funding this project. The University of Florida, U.S. National Park Service, and U.S. Geological Survey also provided support. Many biologists and staff have assisted us in alligator and crocodile captures including J. Beauchamp, G. Blakemore, R. Crespo, M. Denton, I. Fujisaki, L. Hord, E. Larrivee, R. Lynch, J. Vinci and S. Williams. All appropriate access, endangered species, capture, and animal care permits have been obtained and are available for review.

3 Michael S. Cherkiss University of Florida Sections: Crocodile Monitoring Surveys Crocodile Nesting Contributors Brian M. Jeffery University of Florida Section: Alligator Monitoring Alligator Body Condition Alligator Hole Mapping and Occupancy

4 Executive Summary At all life stages, crocodilians integrate biological impacts of hydrologic conditions (Mazzotti and Brandt 1994, Mazzotti 1999, Mazzotti and Cherkiss 2003, Rice et al. 2005, Mazzotti et al. 2009). Florida s two native species of crocodilians the American alligator (Alligator mississippiensis) and the American crocodile (Crocodylus acutus) are important indicators of the health of the Everglades ecosystem because research has linked three key aspects of Everglades ecology to them: (1) Top predators such as crocodilians are directly dependent on prey density, especially aquatic and semi-aquatic organisms, and thus they provide a surrogate for status of many other species. (2) Drier (nests) and wetter (trails and holes) conditions created by ecosystem engineers like alligators provide habitat for plants and animals that otherwise would not be able to survive. This increases diversity and productivity of Everglades marshes (Kushlan and Kushlan 1980, Campbell and Mazzotti 2004, Palmer and Mazzotti 2004) and, therefore, alligator monitoring can indicate overall health of the marsh. (3) The distribution and abundance of crocodilians in estuaries is directly dependent on timing, amount, and location of freshwater flow (Dunson and Mazzotti 1989, Mazzotti and Dunson 1989); crocodiles and alligators exhibit an immediate response to changes in freshwater inputs into the estuaries. Responses of crocodilians are directly related to suitability of environmental conditions including hydropattern (Mazzotti et al. 2009). Correlations between biological responses and environmental conditions contribute to understanding of species status and trends over time. Positive or negative trends of this indicator relative to hydrologic changes permit assessment of positive or negative trends in restoration impacts. Restoration success or failure will be evaluated by comparing recent and future trends and status of crocodilian populations with historical population data and model predictions, as stated in the CERP hypotheses related to alligators and crocodiles (CERP MAP section and , 2004). Importantly, these data can be used in an analysis designed to distinguish between effects of CERP and those of non-cerp events such as hurricanes or droughts. Alligator Alligator Monitoring and Assessment consists of three components designed to measure the impacts of hydrologic change at differing time scales across the entire system: o Relative density o Body Condition o Alligator Hole Occupancy System-wide, relative density measured as encounter rates varied greatly from 0.0/km to 16.9/km in Trends in Big Cypress National Preserve are decreasing, while trends in the remaining areas are stable for water year System-wide, average body condition scores calculated using snout-vent length (SVL) and mass ranged from 2.04 to 2.61 in Trends are stable for water year Alligator hole occupancy in Everglades National Park ranged from 18.27% to 55.01% in 2011.

5 Crocodile Crocodile Monitoring and Assessment consists of four components designed to measure the impacts of hydrologic change at differing time scales across the system: o Relative density o Body Condition o Growth o Survival Encounter rates between areas ranged from 0.02/km to 0.23/km in Body condition scores calculated using SVL and mass varied between areas and ranged from 1.57 to 3.12 in Growth rates between areas ranged from to 0.19 cm/day in One hundred and six confirmed nests were located in 2011 and 849 hatchlings captured and marked for determining hatchling survival. Hatchling survival in 2011 varied between areas and ranged from to I. Introduction and Background The Water Resources Development Act (WRDA) of 2000 authorized the Comprehensive Everglades Restoration Plan (CERP) as a framework for modifications and operational changes to the Central and Southern Florida Project needed to restore the South Florida ecosystem. Provisions within WRDA 2000 provide for specific authorization for an adaptive assessment and monitoring program. A Monitoring and Assessment Plan (MAP) (RECOVER 2004, 2006) has been developed as the primary tool to assess the system-wide performance of the CERP by the REstoration, COordination and VERification (RECOVER) program. The MAP presents the monitoring and supporting research needed to measure the responses of the South Florida ecosystem to CERP implementation. The MAP also presents the system-wide performance measures representative of the natural and human systems found in South Florida that will be evaluated to help determine CERP success. These system-wide performance measures address responses of the South Florida ecosystem that the CERP is explicitly designed to improve, correct, or otherwise directly affect. A separate document, the Development and Application of Comprehensive Everglades Restoration Plan System-wide Performance Measures (RECOVER 2007), has been prepared by RECOVER and provides the scientific, technical, and legal basis for the performance measures. The four broad objectives of MAP are to: 1. Establish pre-cerp reference conditions and variability for each performance measure 2. Determine the status and trends of the performance measures 3. Detect unexpected responses of the ecosystem to changes in stressors resulting from CERP activities 4. Support scientific investigations designed to increase ecosystem understanding, cause and effect, and interpret unanticipated results

6 This study supports the Greater Everglades (GE) Wetlands module of the RECOVER 2004 and 2009 MAP and is directly linked to the monitoring (research) component identified in MAP 2004 as numbers and and RECOVER 2009 MAP as and Because not everything within an ecosystem can be monitored, it is important to select ecological indicators that 1) are representative of the system, 2) integrate system responses, 3) show clear responses to system change, 4) can be effectively and efficiently monitored, and 5) are easily communicated (Schiller et al. 2001, Doren 2006, Doren et al. 2009). Crocodilians (alligators and crocodiles) are one of the indicators that meet these criteria within Everglades ecosystems (Mazzotti et al. 2009). Crocodilians are present throughout virtually all Everglades freshwater wetlands and estuarine areas. These areas include the following RECOVER & Science Coordination Group (SCG) regional modules: Greater Everglades, Florida Bay and Southern Estuaries, Big Cypress, Lake Okeechobee, and the Kissimmee River Basin. Crocodilians are included as attributes in the following conceptual ecological models: Total System, Everglades Ridge and Slough, Southern Marl Prairies (Rocky Glades), Everglades Mangrove Estuaries, and Biscayne Bay. Crocodilians integrate biological impacts of hydrological operations, affecting them at all life stages (Mazzotti and Brandt 1994, Mazzotti 1999, Rice et al. 2005, Mazzotti et al. 2007a), through three key aspects of Everglades ecology: 1. Food webs: Top predators such as crocodilians are dependent on prey density, especially aquatic and semi-aquatic organisms (Barr 1997). Crocodilians are critical in the food web as top predators, influencing abundance and composition of prey (Mazzotti and Brandt 1994). 2. Diversity and productivity: Drier (nests) and wetter (trails and holes) conditions created by ecosystem engineers like alligators provide habitat for plants and animals that otherwise would not be able to survive. This variation in hydrologic conditions created by alligators increases diversity and productivity of Everglades marshes (Kushlan and Kushlan 1980, Campbell and Mazzotti 2004, Palmer and Mazzotti 2004). 3. Freshwater flow: Distribution and abundance of crocodilians in estuaries are directly dependent on timing, amount, and location of freshwater flow (Dunson and Mazzotti 1989, Mazzotti and Dunson 1989). The American crocodile, a federally threatened flagship species, represents the importance of freshwater inflow to estuarine health and productivity (Mazzotti et al. 2007a). CERP and RECOVER MAP Hypotheses and Goals Related to Crocodilians Alligators 1. Restoration of hydropatterns (depth, duration, distribution, and flow) in Southern Marl Prairies/Rocky Glades will expand the distribution and abundance of reproducing alligators and active alligator holes and will restore the keystone role of alligator holes as refugia for aquatic fauna. 2. Restoration of estuarine salinity regimes will expand distribution and abundance of reproducing alligators into oligohaline portions of estuaries.

7 Crocodiles 3. Restoration of hydropatterns in ridge and slough landscape will sustain current populations of alligators and improve body condition of reproducing alligators in ridge and slough landscape. 1. Restoration of freshwater flows and salinity regimes to estuaries will increase growth and survival of crocodiles. 2. Restoration of location of freshwater flow will result in an increase in relative density of crocodiles in areas of restored flow, such as Taylor Slough/C-111 drainage. Concerns about these indicators relate primarily to their respective roles as top predator, keystone species, and ecosystem engineer (American alligator), and top predator, flagship species, estuarine dwelling, and threatened species (American crocodile). Reproduction, growth, and survival of crocodilians are dependent on food availability birds, mammals, fish and macroinvertebrates, which in turn are entirely dependent on hydrologic conditions. Loss of flow and relatively dry hydrologic conditions resulting from water management practices over the past several decades, and loss of habitat (due partly to reduced areas of inundation, increased dry downs, and increased salinization) in portions of the Everglades have adversely affected alligators and crocodiles (Mazzotti and Brandt 1994, Mazzotti and Cherkiss 2003, Rice et al. 2005, Mazzotti et al. 2009). Loss of habitat in Southern Marl Prairies and Rocky Glades and reduction in depth and period of inundation in remaining Everglades wetlands have reduced abundance of alligators and alligator holes in these habitats (Craighead 1968). Other areas are impacted by ponding and timing of increased water depths, resulting in nest flooding (Kushlan and Jacobsen 1990) and reduced body condition (Dalrymple 1996). Reduced prey availability throughout the system as a result of hydrologic alterations corresponds with lower growth, survival and reproduction of alligators (Mazzotti and Brandt 1994). Both alligators and crocodiles have been affected by loss of freshwater flow to estuaries. This loss of flow corresponds with a reduction in distribution and abundance of alligators (Craighead 1968). Although there are higher numbers of crocodiles in more places today than when they were declared endangered, virtually all of that increase is due to crocodiles occupying and nesting in man-made habitats such as the Turkey Point Power Plant site and along the East Cape Canal (Mazzotti and Cherkiss 2003, Mazzotti et al. 2007a). The mangrove back-country of northeastern Florida Bay has consistently been considered core habitat of the American crocodile in Florida (Kushlan and Mazzotti 1989, Mazzotti 1999, Mazzotti et al. 2007a). Today this physically unaltered area suffers from diversion of fresh water (McIvor et al. 1994). This area also has the lowest rates of growth and survival of crocodiles anywhere in Florida (Mazzotti and Cherkiss 2003, Mazzotti et al. 2007a). Because of its unique geographic location and subtropical climate, the Greater Everglades is the only place in the world where both alligators and crocodiles occur. The most important factors affecting regional distribution and abundance of these crocodilians are loss of habitat, hydroperiod, water depth, and salinity (Mazzotti and Brandt 1994, Mazzotti 1999, Mazzotti and Cherkiss 2003, Rice et al. 2005, Mazzotti et al. 2007a). Water management has changed the pattern of water levels in the southern Everglades causing unnatural flooding events and

8 mortality of alligator nests (Kushlan and Jacobsen 1990). Increasing drought frequency and depth of drying have reduced the suitability of Southern Marl Prairie and Rocky Glades habitats and occupancy of alligator holes by alligators. Increasing drought frequency and depth of drying also increase the time required for fish and macroinvertebrate populations to recover to levels considered representative of the historical Everglades (Trexler et al. 2003). When drying events occur repeatedly at less than a 3-8 year interval, fish and macroinvertebrate populations are continually recovering from past droughts and may fail to reach densities sufficient to sustain large predators such as alligators (Loftus and Eklund 1994, Turner et al. 1999, Trexler et al. 2005). Diminished prey density is correlated with lower growth and reproductive rates for alligators in the Everglades compared to other parts of their range (Mazzotti and Brandt 1994). Repeated drying events may also wipe out entire age classes, as alligators are forced to congregate in remaining bodies of water where they may suffer from predation and cannibalism. Water salinity also affects populations of crocodilians (Dunson and Mazzotti 1989, Mazzotti and Dunson 1989). Although American crocodiles are more tolerant of saltwater than alligators, both species prefer fresh to brackish water (Mazzotti 1983). The distribution of alligators in estuaries has been affected by intrusion of saltwater (Craighead 1968, Mazzotti and Brandt 1994). In northeastern Florida Bay occurrence of alligators corresponds with presence of fresh water (Mazzotti 1983). Regionally, lack of fresh water has been correlated with lower growth and survival of crocodiles (Moler 1992, Mazzotti and Cherkiss 2003, Mazzotti et al. 2007a). In a particularly encouraging finding, Mazzotti et al. (2007b) reported that after Buttonwood and East Cape canals in Everglades National Park were plugged in the 1980s to reduce saltwater intrusion into interior areas of Whitewater Bay and Cape Sable, crocodiles responded positively by increasing nesting effort and success. This clear result suggests that restoring salinity patterns in estuaries can have a positive effect on this indicator species and that long-term monitoring is effective at determining population-level responses. It also indicates that nesting effort and success should be added to growth and survival as monitoring parameters. Models of differing levels of complexity have been and are being developed for evaluation and assessment of hydrologic alternatives using crocodilians. The Across Trophic Level System Simulation (ATLSS) alligator model developed in the 1990s simulates the probability of alligator reproduction across the southern Everglades landscape based on hydrological drivers ( An updated alligator production model has been developed using new information obtained from alligator monitoring ( A simple salinity suitability model was developed to evaluate water deliveries to Taylor Slough/C-111 (Mazzotti and Brandt 1995). More sophisticated models are being developed for both species. An estuarine super-model that links responses of spoonbills and crocodiles to hydrology and prey biomass is under development. An alligator population model has been developed that uses input from the alligator production model with functions for growth, dispersal, and survival to produce forecasts for nesting and relative density suitable for assessment of hydrologic alternatives (Slone et al. 2003), and a crocodile population model using the same structure has been completed (Green et al. 2010)

9 Data from this MAP project will simultaneously be used to develop, refine, and validate these new spatially explicit crocodilian population models, which can then be applied in setting interim goals and targets (USACE 2005). This project also fulfills a critical research need (better understanding of the crocodile/salinity relationship) identified as part of RECOVER recommendations for setting interim goals and targets (USACE 2005, Mazzotti et al. 2007a). The objectives of this study follow the recommendations from the MAP, Part 2: 2006 Assessment Strategy for the MAP and the RECOVER GE Trophic Sub-team, to enhance and build upon research and monitoring programs for alligators and crocodiles that have been funded as part of the CESI, Modified Water Deliveries, and RECOVER MAP. This study is designed to satisfy requirements for monitoring changes (over different time scales) in alligator and crocodile populations as a result of restoration. Project Objectives Alligators Monitor changes in alligator populations resulting from restoration over short- (body condition), medium- (distribution, relative density, and hole occupancy) and long-term (demography) temporal scales. Crocodiles Monitor changes in growth, survival, body condition, relative density, and nesting of crocodiles in response to CERP projects. This report summarizes and presents data collected on alligator and crocodiles for the 2011 calendar year. Some results presented here are expressed differently from previous reports because of modifications in reporting methods made at the conclusion of the agreement for the RECOVER MAP. Abundance for alligators is now reported based on transect rather than route data and body condition is calculated using snout vent length (SVL) instead of head length (HL). As a result of changes presented by Mazzotti et al. (2010), quartiles used to evaluate the performance measures have been recalculated and are presented here. II. American Alligator Alligator Relative Density, Demography and Condition Introduction Relationships among dry season refugia, aquatic fauna, wading birds, and alligators have been identified as key uncertainties in the Comprehensive Everglades Restoration Plan (CERP) (U.S. Army Corps of Engineers 1999). Due to the alligator s ecological importance and known sensitivity to hydrology, salinity, habitat productivity, and total system productivity, it was chosen as an indicator of restoration success in the RECOVER Monitoring and Assessment Plan. Relative distribution, relative body condition, and occupancy rates of alligator holes can be used to determine success of CERP projects at different spatial and temporal scales. The relative density of alligators is expected to increase as hydrologic conditions improve in over-drained marshes and freshwater tributaries. As canals are removed, densities of alligators in adjacent marshes and occupancy of

10 alligator holes is expected to increase. As more natural hydropatterns are restored, body condition scores are expected to improve. Methods Spotlight and capture surveys were used to determine demography, relative density, and condition of alligators throughout the Everglades (Figure II-1). Spotlight counts are an accepted means of monitoring populations of crocodilians (Bayliss 1987, Hutton and Woolhouse 1989). Surveys were conducted in marshes, canals, and estuaries in the dry season, and marshes and estuaries in the wet season (Figure II-1) following protocols described in Mazzotti et al. (2010). Variation in detectability of alligators due to environmental conditions (air temperature and wind speed) is controlled by adhering to established survey protocols. To determine condition of marsh alligator populations, semi-annual capture surveys were performed near spotlight survey routes. Condition was calculated using snout-vent length (SVL) by using Fulton s K: (SVL/Weight 3 )*10 5. A minimum of 15 alligators greater than 1.25 m total length were captured in each area by hand, noose or tongs in the fall and spring of each year. Previous work has shown that 15 animals is adequate to detect a 10% per year decline in condition over three years with a minimum power of 90% and alpha = 0.05 (Mazzotti et al. 2010). Total length (TL), SVL, head length (HL), tail girth (TG), and weight were measured, animals were sexed, and any abnormalities/deformities were noted. Alligators were tagged using Florida Fish and Wildlife Conservation Commission web tags or by clipping scutes to identify recaptured individuals. Geographic location, habitat characteristics, and environmental characteristics including air/water temperature, water depth, muck depth, and salinity were recorded where applicable. Occupancy rate of alligator holes was determined by helicopter surveys conducted in areas expected to be influenced most by CERP (Rocky Glades, Northeast Shark Slough, and Shark Slough) during the dry season (April June). This method entails flying along transects at 500- meter E-W intervals. Observers sit on both sides of the helicopter and it is assumed that each observer can identify an alligator hole at a distance of up to 250 meters, so that all alligator holes within a given area of flown transects are observed. The helicopter flew at an average height of 46 meters (150 feet) above ground, hovering at 15 meters (50 feet) to provide researchers a closer look at holes observed. When an alligator hole was detected, the pilot navigated from the transect to an observed hole. At each observed alligator hole the following information was recorded: whether or not an alligator is present, sizes of observed alligator(s), and whether or not the hole contains water or is dry. A GPS point was taken at every observed alligator hole. Holes are considered occupied if an alligator was in the hole or located within a short distance of the hole (e.g., in a trail or basking next to the hole). A reassessment of targets (based on quartiles) for relative density (encounter rate), body condition (Fulton s K), and alligator hole occupancy (percent occupied) was performed on data from (Figure II-1). The previous targets were based on data collected from a subset of areas that are currently sampled and this reexamination of data will provide a better understanding of current status in relation to restoration goals.

11 Results Relative Density- Spring and fall alligator surveys were conducted in 9 marsh and 1 estuary areas (Figure II-2, Table II-1). Spring surveys could not be conducted in BICY, ENP-SS, ENP-FC, WCA3A-TW, and WCA3B due to extreme drought conditions. Quartiles for relative density fall into the following categories: red, first and second quartile which is well below restoration criteria; yellow, third quartile which does not meet restoration criteria; and green, fourth quartile which meets restoration target (Table II-2). Spring encounter rates for marsh transects ranged from 0.0 alligators/km (ENP-EST) to 16.9 alligators/km (A.R.M. Loxahatchee National Wildlife Refuge-LOX; Figure II-3). Average relative densities in the spring for ENP-EST fell into the first quartile and WCA2A fell into the second quartile, which are red and are well below restoration criteria. Average relative densities for LOX, WCA3A-HD, and WCA3A-N41 fell into the fourth quartile, which are green and meets restoration target. Fall encounter rates for marsh transects ranged from 0.0 alligators/km (BICY) to 5.4 alligators/km (LOX; Figure II-3). Average relative densities for BICY, ENP-FC, ENP-SS, WCA3A-TW, WCA3B, ENP-EST and WCA2A fell into the first and second quartile, which are red and are well below restoration criteria. Average relative densities for WCA3A-HD and WCA3A-N41 fell into the third quartile, which are yellow and do not meet restoration criteria. Body Condition-Alligator captures were conducted in spring and fall in 9 marsh and 1 estuary area (Figure II-1, Table II-3). Alligator captures were not conducted in BICY, ENP-FC, ENP-SS, WCA2A, WCA3A-TW, WCA3A-HD, WCA3A-N41, and WCA3B due to drought conditions. A total of 37 (18 female and 19 male) alligators were captured in spring. Of those captured 30 were new individuals and 7 were recaptures. A total of 160 (77 female and 83 male) alligators were captured in fall. Of those captured, 132 were new individuals and 28 were recaptured individuals. Alligator captures in the spring ranged from 135.9cm to 282.3cm TL and average body condition index scores (all areas) calculated using SVL ranged from 2.08 to 2.18 (Table II- 4). Quartiles for body condition fall into the following categories: red, first quartile which is well below restoration criteria; yellow, second and third quartile which does not meet restoration criteria; and green, fourth quartile which meets restoration target (Table II-5). Body condition scores for ENP-EST and LOX fell into the second quartile (yellow) which does not meet restoration criteria, WCA2A fell into the third quartile (yellow) which does not meet restoration criteria, and WCA3A-HD and WCAN41 fell into the fourth quartile (green) which meets restoration target (Table II-5). Fall alligator captures ranged from 113.1cm to 310.8cm and average body condition index scores (all areas) ranged from 2.04 to 2.61 (Table II-4). Body condition scores for BICY, ENP-FC, ENP-SS, WCA3A-TW, and WCA3B fell into the first quartile (red) which is well below restoration criteria, ENP-EST and WCA2A fell into the second quartile (yellow) which does not meet restoration criteria, WCA3A-HD and WCA3A- N41 fell into the third quartile (yellow) which does not meet restoration criteria, and LOX fell into the fourth quartile (green) which meets restoration target (Table II-5).

12 Hole Occupancy-Spring alligator hole occupancy flights were conducted in Northeast Shark Slough (NESS, 18 transects), Shark Slough (SS, 15 transects), and Rocky Glades (RG, 19 transects; Figure II-2). Restoration goals were determined by frequency diagram of all measures of occupancy during in ENP along with historical information from Campbell and Mazzotti (2004) as well as historical information by Craighead (1968; Figure II-1). By transect 0.0 to 7.9% of holes observed had alligators present. By area average occupancy was 50.6% for NESS, 53.14% for SS, which are yellow and in the second division and are below restoration target. Average occupancy was 16.8% for RG which are in the first division and red, which is well below restoration target. Discussion Relative Density- In general, total count densities were much lower in the Everglades than other parts of Florida. While the Everglades populations were probably never as dense as those in the more eutrophic waters of north-central Florida, the densities in many current natural areas are certainly depressed. This may be due to a combination of the natural low-nutrient state of the Everglades and a loss of habitat and alterations in water management regimes. This is especially evident in the WCA3A-TW (north of I-75) and WCA3B surveys, both areas that have extreme dry conditions during most years which likely results in lower reproduction and lower juvenile survival. As in surveys elsewhere for alligators, most of our counts were higher during low water periods in spring. Our survey routes are primarily along airboat trails which hold water longer than the surrounding marsh. As with natural sloughs, these trails dry out more slowly than the surrounding marsh and provide the only standing water where alligator can concentrate. All areas have no trends for the last five years for relative density except for BICY which has a negative trend. This is a concern as relative density remains constant or decreasing, the restoration target will not be achieved. Small and juvenile alligators are encountered less frequently than adults. With the exception of LOX and WCAN-41, small and juvenile alligators are rarely encountered. The continuous dry downs from water management and droughts over the last several years may have contributed to the decline of small and juvenile numbers. Dry downs reduce the areas where small and juvenile alligators can hide from predators. In the event of a total dry down (no standing water), small and juvenile alligators do not have the reserves (both nutritional and hydrological) to survive. Without the next generation of alligators, the future number of adult alligators will be on the decline and restoration goals will not be achieved. Body Condition- Overall, body condition index scores were higher in the fall than in the spring in the three areas (LOX, WCA3A-HD, and ENP-EST) where we were able to compare values. In general, as the marsh water levels decrease in the spring, aquatic prey are forced to seek refuge in deeper water refuge. When water levels drop to below the substrate, most often the only refuge available are alligator holes. Alligators take advantage of increased prey density to build fat reserves for mating, egg development, and survival. Due to the extreme drought, prey availability may have decreased during the spring. In some areas, alligator holes dried completely leaving no refugia for prey. Trends for body condition over the last three years are stable, but most areas do not meet restoration goals.

13 Hole Occupancy- Alligator hole occupancy was very low compared to past years, most likely due to low water levels during our surveys. All of the sites were extremely dry at the time of our surveys, with many holes drying up and no water present in the surrounding marsh. Thus, if alligators were present they may have been buried in the mud. In Shark Slough, holes still contained water, and water was present in the some surrounding marsh habitats. Trends for alligator hole occupancy are stable and do not meet restoration goals.

14 Table II-1. Alligator survey summaries for spring and fall Date Route Name Habitat Transect Transect Length (km) Hatchling Large Medium Small Unknown Total non-hatchling (excluding unknowns) 08-Sep-11 BICY Marsh Marsh Sep-11 BICY Marsh Marsh Sep-11 BICY Marsh Marsh Sep-11 BICY Marsh Marsh Mar-11 ENP-EST River Mar-11 ENP-EST River Mar-11 ENP-EST River Mar-11 ENP-EST River Sep-11 ENP-EST River Sep-11 ENP-EST River Oct-11 ENP-EST River Oct-11 ENP-EST River Sep-11 ENP-FC Marsh Sep-11 ENP-FC Marsh Sep-11 ENP-FC Marsh Sep-11 ENP-FC Marsh Sep-11 ENP-FC Marsh Sep-11 ENP-FC Marsh Sep-11 ENP-SS Marsh Sep-11 ENP-SS Marsh Sep-11 ENP-SS Marsh Sep-11 ENP-SS Marsh Mar-11 LoxL39 Canal Mar-11 LoxL39 Canal Apr-11 LoxL39 Canal Apr-11 LoxL39 Canal

15 Table II-1. Continued Date Route Name Habitat Transect Transect Length (km) Hatchling Large Medium Small Unknown Total non-hatchling (excluding unknowns) 13-Mar-11 LoxL40 Canal Apr-11 LoxL40 Canal Mar-11 LoxMarsh Marsh Mar-11 LoxMarsh Marsh Mar-11 LoxMarsh Marsh Mar-11 LoxMarsh Marsh Sep-11 LoxMarsh Marsh Sep-11 LoxMarsh Marsh Oct-11 LoxMarsh Marsh Oct-11 LoxMarsh Marsh Feb-11 WCA2A Canal Canal Mar-11 WCA2A Canal Canal Feb-11 WCA2A Marsh Marsh Feb-11 WCA2A Marsh Marsh Mar-11 WCA2A Marsh Marsh Mar-11 WCA2A Marsh Marsh Sep-11 WCA2A Marsh Marsh Sep-11 WCA2A Marsh Marsh Sep-11 WCA2A Marsh Marsh Sep-11 WCA2A Marsh Marsh Feb-11 WCA3A-HD Canal Canal Feb-11 WCA3A-HD Marsh Marsh Feb-11 WCA3A-HD Marsh Marsh Sep-11 WCA3A-HD Marsh Marsh Sep-11 WCA3A-HD Marsh Marsh Sep-11 WCA3A-HD Marsh Marsh Sep-11 WCA3A-HD Marsh Marsh Feb-11 WCA3A-N41 Canal Canal

16 Table II-1. Continued Date Route Name Habitat Transect Transect Length (km) Hatchling Large Medium Small Unknown Total non-hatchling (excluding unknowns) 09-Mar-11 WCA3A-N41 Canal Canal Feb-11 WCA3A-N41 Marsh Marsh Feb-11 WCA3A-N41 Marsh Marsh Mar-11 WCA3A-N41 Marsh Marsh Mar-11 WCA3A-N41 Marsh Marsh Sep-11 WCA3A-N41 Marsh Marsh Sep-11 WCA3A-N41 Marsh Marsh Sep-11 WCA3A-N41 Marsh Marsh Sep-11 WCA3A-N41 Marsh Marsh Sep-11 WCA3A-TW Marsh Marsh Sep-11 WCA3A-TW Marsh Marsh Sep-11 WCA3A-TW Marsh Marsh Sep-11 WCA3A-TW Marsh Marsh Sep-11 WCA3B Marsh Marsh Sep-11 WCA3B Marsh Marsh Sep-11 WCA3B Marsh Marsh Sep-11 WCA3B Marsh Marsh

17 Table II-2. Alligator relative density quartile rankings based on data. Quartile Relative Abundance Indicator Color Color Meaning 1st Red Well below restoration goals 2nd Red Well below restoration goals 3rd Yellow Below restoration goals 4th >1.7 Green Meets restoration goals

18 Table II-3. American alligator capture data from 2011, snout-vent length (SVL), Total length (TL), and tail girth (TG) were measured in centimeters (cm) and weight in kilograms (kg). Web Capture Date Area Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 20-Feb-11 WCA3A-HD No F 21-Feb-11 WCA3A-HD Yes F 21-Feb-11 WCA3A-HD No F 11-Mar-11 ENP-EST No F 16-Mar-11 ENP-EST No M 16-Mar-11 ENP-EST No M 16-Mar-11 ENP-EST Yes M 16-Mar-11 ENP-EST Yes M 16-Mar-11 ENP-EST No M 16-Mar-11 ENP-EST Yes M 16-Mar-11 ENP-EST Yes M 16-Mar-11 ENP-EST No F 16-Mar-11 ENP-EST No M 17-Mar-11 ENP-EST No M 17-Mar-11 ENP-EST No M 17-Mar-11 ENP-EST No F 17-Mar-11 ENP-EST No F 22-Mar-11 ENP-EST No M 22-Mar-11 ENP-EST Yes M 23-Mar-11 ENP-EST No M 30-Mar-11 LOX 1170 No M 30-Mar-11 LOX 1171 No F 30-Mar-11 LOX 1172 No F 30-Mar-11 LOX 1173 No M 30-Mar-11 LOX 1174 No M 30-Mar-11 LOX 1175 No F 30-Mar-11 LOX 1176 No M 30-Mar-11 LOX 1177 No F 30-Mar-11 LOX 149 Yes M 30-Mar-11 LOX 1162 No F 30-Mar-11 LOX 1163 No F 30-Mar-11 LOX 1164 No F 30-Mar-11 LOX 1165 No F 30-Mar-11 LOX 1166 No F 30-Mar-11 LOX 1167 No F

19 Table II-3. Continued Capture Date Area Web Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 30-Mar-11 LOX 1168 No F 28-Apr-11 LOX 1187 No M 28-Apr-11 LOX 1818 No M 28-Apr-11 LOX 1189 No M 28-Apr-11 LOX 1190 No F 28-Apr-11 LOX 1191 No M 28-Apr-11 LOX 1192 No F 28-Apr-11 LOX 1193 No F 28-Apr-11 LOX 1186 No M 28-Apr-11 LOX 1169 No M 28-Apr-11 LOX 1062 Yes F 28-Apr-11 LOX 1181 No M 28-Apr-11 LOX 1178 No F 28-Apr-11 LOX 1179 No F 28-Apr-11 LOX 1180 No F 28-Apr-11 LOX 1182 No M 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD 999 No F 11-May-11 WCA3A-HD No M 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No F 11-May-11 WCA3A-HD No F 17-May-11 LOX 1194 No M 02-Jul-11 ENP-EST No M 28-Sep-11 LOX 1193 No M 28-Sep-11 LOX 248 Yes F 28-Sep-11 LOX 1223 Yes M 28-Sep-11 LOX 209 Yes M 28-Sep-11 LOX 1194 No M 28-Sep-11 LOX 1195 No M

20 Table II-3. Continued Capture Date Area Web Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 28-Sep-11 LOX 1196 No F 28-Sep-11 LOX 1197 No M 29-Sep-11 LOX 1198 No M 29-Sep-11 LOX 1199 No F 29-Sep-11 LOX 1200 No F 29-Sep-11 LOX 1204 No M 29-Sep-11 LOX 1201 No F 29-Sep-11 LOX 1202 No F 29-Sep-11 LOX 1203 No M 29-Sep-11 LOX 1205 No M 04-Oct-11 ENP-EST No M 04-Oct-11 ENP-EST No M 04-Oct-11 ENP-EST No M 04-Oct-11 ENP-EST No F 04-Oct-11 ENP-EST No F 05-Oct-11 BICY No M 05-Oct-11 BICY Yes M 05-Oct-11 BICY No M 05-Oct-11 BICY No M 05-Oct-11 BICY No F 05-Oct-11 BICY No M 05-Oct-11 BICY No M 05-Oct-11 BICY No M 05-Oct-11 ENP-EST No F 05-Oct-11 BICY No M 05-Oct-11 BICY No F 05-Oct-11 BICY Yes F 05-Oct-11 BICY No F 05-Oct-11 ENP-EST No F 06-Oct-11 BICY No M 06-Oct-11 BICY No M 12-Oct-11 BICY No M 12-Oct-11 BICY No F 20-Oct-11 ENP-SS No M 20-Oct-11 ENP-SS No M 20-Oct-11 ENP-SS No M 20-Oct-11 ENP-SS No F 20-Oct-11 ENP-SS Yes F 20-Oct-11 ENP-SS Yes F

21 Table II-3. Continued Capture Date Area Web Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 20-Oct-11 ENP-SS Yes F 20-Oct-11 ENP-SS Yes F 25-Oct-11 ENP-EST No M 25-Oct-11 ENP-EST No M 25-Oct-11 ENP-EST Yes M 25-Oct-11 ENP-EST No M 25-Oct-11 ENP-EST No F 25-Oct-11 ENP-EST No M 26-Oct-11 ENP-EST No M 26-Oct-11 ENP-EST No M 27-Oct-11 ENP-SS Yes M 27-Oct-11 ENP-SS No F 27-Oct-11 ENP-SS Yes F 27-Oct-11 ENP-SS Yes F 27-Oct-11 ENP-SS No F 27-Oct-11 ENP-SS Yes M 27-Oct-11 ENP-SS No F 01-Nov-11 ENP-EST Yes M 01-Nov-11 ENP-EST Yes M 01-Nov-11 ENP-EST No M 02-Nov-11 WCA3A-TW No M 02-Nov-11 WCA3A-TW Yes M 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW Yes F 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW No M 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW No M 02-Nov-11 WCA3A-TW No F 02-Nov-11 WCA3A-TW No M 03-Nov-11 ENP-FC Yes M 03-Nov-11 ENP-FC Yes M 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No F 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No M

22 Table II-3. Continued Capture Date Area Web Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 03-Nov-11 ENP-FC No F 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No F 03-Nov-11 ENP-FC No F 03-Nov-11 ENP-FC No F 03-Nov-11 WCA3A-TW No M 03-Nov-11 ENP-FC No M 03-Nov-11 ENP-FC No F 07-Nov-11 WCA3A-HD No M 07-Nov-11 WCA3A-HD No M 07-Nov-11 WCA3A-HD No F 07-Nov-11 WCA3A-HD No F 07-Nov-11 WCA3A-HD No M 07-Nov-11 WCA3A-HD No F 07-Nov-11 WCA3A-HD No F 07-Nov-11 WCA3A-HD No M 07-Nov-11 WCA3A-HD No F 08-Nov-11 WCA3A-HD No M 08-Nov-11 WCA3A-HD No F 08-Nov-11 WCA3A-HD No F 08-Nov-11 WCA3A-HD No F 08-Nov-11 WCA3A-HD No F 08-Nov-11 WCA3A-HD No F 09-Nov-11 WCA3A-TW No M 09-Nov-11 WCA3A-TW No M 09-Nov-11 WCA3A-TW No F 09-Nov-11 WCA3A-TW Yes F 10-Nov-11 WCA3B No M 10-Nov-11 WCA3B No M 10-Nov-11 WCA3B No M 10-Nov-11 WCA3B Yes M 10-Nov-11 WCA3B No M 10-Nov-11 WCA3B No F 10-Nov-11 WCA3B No M 10-Nov-11 WCA3B No F 10-Nov-11 WCA3B Yes F 10-Nov-11 WCA3B Yes F 10-Nov-11 WCA3B No F

23 Table II-3. Continued Capture Date Area Web Tag/Scute Clip Recapture SVL (cm) TL (cm) TG (cm) Weight (kg) Sex 10-Nov-11 WCA3B No F 10-Nov-11 WCA3B No F 10-Nov-11 WCA3B No F 10-Nov-11 WCA3B No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No F 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No M 15-Nov-11 WCA2A No F 15-Nov-11 WCA2A Yes F 15-Nov-11 WCA2A No F 15-Nov-11 WCA2A No F 15-Nov-11 WCA2A No F 17-Nov-11 WCA3A-N No M 17-Nov-11 WCA3A-N No M 17-Nov-11 WCA3A-N No M 17-Nov-11 WCA3A-N Yes F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No M 17-Nov-11 WCA3A-N No M 17-Nov-11 WCA3A-N Yes F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N Yes F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F 17-Nov-11 WCA3A-N No F

24 Table II-4. Average alligator body condition for spring and fall in capture areas in First quartile , second quartile , third quartile , and fourth quartile >2.27. Area Average Spring Body Condition Average Fall Body Condition Big Cypress National Preserve A.R.M Loxahatchee National Wildlife Refuge Everglades National Park (ENP) EST ENP-FC ENP-SS Water Conservation Area (WCA) 2A WCA3A-TW WCA3A-HD WCA3A-N WCA3B

25 Table II-5. Quartile ranks for body condition of alligators for data. Quartile Body Condition Score Indicator Color Color Meaning 1st Red Well below restoration goals 2nd Yellow Below restoration goals 3rd Yellow Below restoration goals 4th >2.27 Green Meets restoration goals

26 Figure II-1. Quartile and category divisions for alligators A. Relative density (alligators/km) B. Body condition (Fulton s K) C. Alligator hole occupancy (percent occupied). Data are from

27 LOX WCA3A-TW WCA2A WCA3A-HD WCA3A-N41 WCA3B BICY ENP-FC ENP-SS ENP-EST Figure II-2. American alligator marsh survey routes for Captures are conducted in close proximity to survey routes.

28 NESS SS RG Figure II-2. East and west end points for American alligator hole occupancy transects within Everglades National Park in Shark Slough is SS, Rocky Glades is RG, and Northeast Shark Slough is NESS.

29 Alligators/km Fall Spring Area Figure II-3. Alligator relative abundance by transect for spring and fall First and second quartile ( alligators/km) are red and are well below restoration target, third quartile ( alligators/km) are yellow and are below restoration target, and the fourth quartile (>1.70 alligators/km) meet restoration target.

30 III. American Crocodile Monitoring of Nesting, Body Condition, Relative Density, Growth and Survival Rates of Crocodiles Introduction Monitoring and Assessment Plan (MAP) project tasks for crocodiles are divided into conducting monitoring surveys and evaluating and refining sampling parameters and methods. Monitoring surveys for crocodiles are designed to test the CERP hypothesis that restoration of freshwater flows to estuaries and salinity regimes will increase growth and survival of crocodiles. Determining growth and survival is dependent on finding and marking hatchling crocodiles, therefore monitoring nests is also a component of this task. In this report we present results of crocodile monitoring surveys for Methods Growth, survival, body condition, and relative density, of crocodiles were measured by survey and capture efforts. Surveys were performed three times in 2011 (January-March, April- June and October-December) throughout coastal areas including the Biscayne Bay Complex (BBC, including Biscayne Bay, Card and Barnes Sounds), NE Florida Bay and the Flamingo Cape Sable area (Figure III-1). Growth and survival were determined by efforts to recapture marked crocodiles during survey efforts. Non-hatchling crocodiles were captured by hand, tongs, net, or by wire-noose as described by Mazzotti (1983). All crocodiles captured were weighed and measured. Total length (TL), snout-vent length (SVL), head length (HL), tail girth (TG) and gender were measured for all non-hatchling crocodiles, with TL, SVL and mass only, recorded for hatchlings. First time captures were marked by removing tail scutes according to a prescribed sequence (Mazzotti 1983). Geographic location and environmental characteristics including air/water temperature and salinity were recorded at each observation. Growth rate was determined using changes in total length (TL) for all recaptured individuals. Minimal survival was defined as proportion of hatchling crocodiles known to have survived for at least 12 months. Minimum survival does not differentiate between death, dispersal, and wariness. To determine condition of crocodiles, condition was calculated using snout-vent length (SVL) by using Fulton s K: (Weight/SVL 3 )*10 5. Nest surveys extended from Biscayne Bay south following the coastline (including islands) through Everglades National Park to Highlands Beach and were conducted by motorboat, jon boat, canoe, foot, and helicopter during June through August (hatching period). Nests were located from evidence of crocodile activity (tail drags, digging, and scraping), and successful nests were determined by presence of hatchlings or hatched shells. Florida Power and Light Company (FPL) conducted nest surveys at the Turkey Point Power Plant site, and Florida Fish and Wildlife Conservation Commission (FWC) conducted nest surveys at the Crocodile Lake National Wildlife Refuge (CLNWR).

31 Results Relative Density-Spotlight surveys conducted in 2011 resulted in 181 crocodile observations, 30 alligator observations and 215 indistinguishable eyeshines (Table III-1). While a few more crocodiles were observed in 2011 than in 2010, observations were still lower than previous years (Figure III-2). Crocodile observations (observed and captured) ranged in size from cm TL. Seventy-one crocodile captures were made during spotlight surveys and of those, 45 were recaptures (Table III-1). For the 45 individuals for which sex could be determined, 21 were female and 24 male. Encounter rates varied between survey period and area, ranging from 0.02 crocodiles/km in NE Florida Bay and BBC to 0.28 crocodiles/km in the Flamingo/Cape Sable area (Table III-2). Growth and Survival- We estimated growth rates of 32 individual crocodiles whose data from original captures and most recent captures from 2011 were available. Quartiles for crocodile growth fall into the following categories: red, first quartile which is well below restoration criteria; yellow, second and third quartiles which do not meet restoration criteria; and green, fourth quartile which meets restoration target (Table III-3). Growth rate varied between the three areas, BBC was 0.05cm/day, (N=2), NE Florida Bay averaged 0.06 (range , N=4) and the Flamingo/Cape Sable area averaged (range , N=26). With regard to the stoplight indicator categories for survival, is red, yellow and 0.85 green. Survival varied between areas as well, with BBC having a survival rate of 0.607, NE Florida Bay and the Flamingo/Cape Sable area 0.495, all three areas are in the red for survival subcomponent. Body Condition- During 2011, body condition varied between the three nesting areas, BBC averaged 2.09 (range , N=15), NE Florida Bay averaged 2.07 (range , N=10) and the Flamingo/Cape Sable area averaged 2.18 (range , N=44). Quartiles for crocodile body condition are in the process of being calculated. Nesting-One hundred and six confirmed nests were located during the 2011 nesting season during surveys conducted under this agreement, 101 within ENP, one nest at Chapman Field County Park (depredated), and one nest at Deering Bay, Ocean Reef on North Key Largo and two at Crocodile Lake National Wildlife Refuge (Table III-4). For nests whose fate was known, ninety-seven percent (103) were successful, 2% (2) were depredated by raccoons and the remaining nest failed for unknown reasons. A total of 849 hatchlings were captured during the hatching season (Table III-5). Discussion Relative Density- During the 2011 survey period, crocodiles were observed throughout the survey area and in the same locations as in recent years. However, few juveniles were observed in 2010 and This decrease could be a result of the extreme cold event of 2010, in which over 100 crocodiles died. We are in the process of developing guidelines for using density as a performance measure to meet our changes described in (Mazzotti et al. 2010).This demonstrates

32 the effectiveness of current survey techniques at finding and catching crocodiles, and supports the practicality of using growth and survival as performance measures for Everglades restoration. Growth and Survival-Growth and survival includes all size classes, as proposed in Mazzotti et al. (2010). Growth rates in 2011 fell within the range ( to 0.16 cm/day reported by Mazzotti et al. (2007b) (Table III-6). Sixty-three percent of crocodiles caught were recaptures. This high rate of recaptures is impressive for a crocodilian study and allows for increased confidence rates of crocodile growth and survival. Body Condition- While condition was higher in all areas during 2011 than 2010, and highest in the Flamingo/Cape Sable area, this is data from short time period and so interpretation is not possible. We are in the process of developing guidelines for using body condition as a performance measure to meet our changes described in (Mazzotti et al. 2010). Nesting-There were 101 confirmed nests located in ENP during the 2011 nesting season. This is an increase from the two previous seasons, but well below the peak in nesting recorded during the 2008 nesting season (Figure II-3). Mazzotti (1989) defined optimal nesting habitat for American Crocodiles as presence of elevated, well drained, nesting substrate adjacent to relatively deep (greater than 1 m), low to intermediate salinity (< 20 ppt) water, protected from effects of wind and wave action, and free from human disturbance. Man-made nesting areas along canal banks (berms) at CLNWR, East Cape Canal in ENP, and the cooling canal system at TP provide nearly ideal nesting conditions. As exemplified in South Florida, one of the most striking aspects of nesting habits of the American Crocodile is a crocodile s ability to find and use artificial substrates for nesting. In fact, virtually the entire increase of crocodiles nesting in Florida is due to nesting on artificial substrates in the Cape Sable/Flamingo area of ENP on canal banks that were created more than 40 years ago (Beard 1938, Lodge 1994), and on the peat canal banks created at CLNWR, and at TP (Mazzotti 1983, Ogden 1978). Mazzotti et al. (2007b) hypothesized that plugging canals in the Cape Sable/Flamingo area in the 1980s and 1990s to reduce saltwater intrusion and retain fresh water provided more suitable habitat for nesting for the few crocodiles present in the area and for growth and survival of hatchling crocodiles. Crocodiles responded positively and the rapid increase in nesting effort and success observed in the Cape Sable/Flamingo area of ENP since 2000 may be the result of offspring of the original nesting crocodiles on artificial substrates at East Cape Canal entering the breeding population (Mazzotti et al. 2007a) and explains a majority of the increase in nesting observed within ENP. This suggests that restoring salinity patterns in estuaries can have a positive effect on this indicator and that monitoring is effective at determining population responses.

33 Figure III-1. Summary of American crocodile routes for surveys performed during 2011.