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4. Habitat and Species Recovery Projects
Projects to Recover Vegetative Communities and Multiple Animal Species
Project Purpose and Major DOI Interest
Protected species have differing habitat requirements. In several of South Florida's ecological communities, conditions that are optimal for one species are detrimental to others. Consequently, the restoration of native habitats may displace or otherwise adversely affect protected species that have adapted to a disturbed condition and currently use a site. Similarly, management actions designed to benefit a particular species or community may adversely affect species or communities in another part of the system. For example, management options for restoring more natural hydrologic patterns within Everglades National Park may benefit some protected species within the park and adversely affect others that reside in habitats upstream from the park.
The purpose of avian multi-species conservation is to optimize the benefits of restoration for protected avian species in South Florida while minimizing tradeoffs caused by conflicting habitat needs. This requires a multi-species approach to management and a thorough understanding of how management will affect a wide variety of species.
What Is Known
Still more information is needed to refine habitat models and to define in detail the requirements of several species that will be affected by the CERP and other restoration projects. In particular, the ability to project the long-term population responses of species with differing degrees of habitat specificity, population elasticity, and freedom of movement needs to be improved to ensure that restoration is not accomplished at the expense of particular species or critical ecosystem components, when measures could be employed to avoid or minimize impacts.
In 2004 and 2005, the FWS was able to provided Reprogrammed funds to initiate over 20 new research projects involving these avian species issues that will directly address many of the high-priority research and information needs identified herein. Results from these projects are just beginning to become available. Once the primary information needs are addressed, another suite of needs will doubtless arise that will allow further improvement of management actions, and we are beginning to formulate the next generation of needs as the primary information gaps are filled.
What Is Needed
Research and possible model refinement to support decision making where restoration activities pose the potential for multi-species tradeoffs. Detailed studies of the habitat requirements of individual species in potential conflict will improve understanding of the key factors to be considered in management decisions, thereby reducing the potential for adverse effects on the species. In addition to the four focal species discussed previously, the Avian Ecology Workshop panelists identified a need to evaluate other species that may be more sensitive to wetland restoration. Evaluating these other species will both aid in avoiding potential detrimental impacts and provide additional information about responses to restoration actions that can be used to fine-tune projects within an adaptive management framework.
For Everglades wetland birds, priority studies include the following:
Outside, as well as within, the Everglades, priority studies include the following:
Landscape-scale ecological modeling. Improved species-habitat information and demographic data will support development of improved ecological models. Such models will allow investigation of how hydrologic change, habitat change, and population characteristics interact to affect the survival and persistence of a suite of avian species in South Florida. Such models will improve managers' abilities to predict species' responses and optimize restoration projects.
Identification of optimality and critical limiting factors. The ability of models to accurately represent and predict species responses to conditions requires a detailed understanding of the critical limiting factors and accurate representation of optimal conditions. Closely-related avian species may be limited by different resources, or during different times within the life cycle.
For example, the hydrologic conditions that allow Everglade snail kite nesting and foraging are well-known. However, the additional complexity of the their dependence on apple snails, and the necessity of also incorporating the hydrologic conditions that maintain healthy populations of apple snail make identifying optimal hydrologic conditions for snail kite nesting and foraging difficult. Similarly, identifying the hydrologic conditions that critically limit the snail kite population are also difficult. For many of the avian species, the current resolution of information may only allow resource managers to determine whether resource and environmental needs are generally consistent among a suite of species, but information is lacking to truly optimize the relationships. Integrating information across disciplines and across research projects currently appears to offer the greatest potential to improve our understanding of critical limiting factors and optimal relationships with respect to many species.
Evaluating diverse threats Scientists working to develop population models to predict the responses of avian species to restoration and other habitat modifications usually look to empirical measurements of species populations to calibrate and validate models. This approach assumes that the primary factors affecting the focal taxon's population is habitat conditions or quality. Identifying and understanding other possible mechanisms that affect a taxon's population, such as disease, accidental mortality, catastrophic events, and competition with other species may help clarify modeling results. In addition, understanding the role of these possible factors, as well as potential interactions among several mechanisms, is essential to achieving effective management.
Determination of connectivity and importance of South Florida populations for widely distributed species. Additional information is needed on the interactions of South Florida populations and other populations of some species that are relatively widely distributed and mobile. The Avian Ecology Workshop panel recognized the need to evaluate how effects in a portion of a species' range will affect the population as a whole. The wood stork, roseate spoonbill, and Everglade snail kite all have distributions that extend beyond the Everglades and South Florida, and they are all mobile to varying degrees. Confidently predicting the responses of such species requires a solid understanding of what portions, if any, of the species' distribution is critical to the well-being of the population. On a smaller scale, similar information is needed to predict the responses of different subpopulations of the locally distributed Cape Sable seaside sparrow as habitat conditions change in response to restoration activities within portions of their current range.
Development of species-specific information needed for recovery planning. Some species will require focused biological investigations to support conservation planning. The Avian Ecology Workshop panel identified species-specific needs, particularly for the Cape Sable seaside sparrow. These measures include evaluation of translocation as a management tool, improved knowledge of nest success and productivity in relation to habitat conditions, and more detailed understanding of demographic parameters and the variability in these parameters among subpopulations and under different conditions. Additional actions are discussed under "Recovery of Cape Sable Seaside Sparrow," page 100. As mentioned above, the Everglade snail kite is another species that warrants collection of detailed information and may require focused management actions. Recent trends in data suggest that the current level of information may not be sufficient to ensure protection for kites.
Studies of migratory birds in South Florida. Significant information gaps exist for unlisted bird species that are protected under the Migratory Bird Treaty Act. Surveys and studies conducted to understand the importance of South Florida habitat to these species, their sensitivity and resilience to manageable human impacts, and the potential impacts and benefits of hydrological restoration projects, especially the CERP, will help ensure that these migratory species are not inadvertently adversely affected by projects intended to benefit other protected avian species.
Monitoring plan for the avian species component of the MSRP
Recovery of Scrub Community:
Project Purpose and Major DOI Interest
As a result of conversion to citrus farms and other forms of development, scrub communities have disappeared in disproportionate amounts compared to many other types of habitat, such as pine flatwoods, and they are becoming an increasingly rare habitat type in Florida. By the early 1980s an estimated 66% of scrub habitat had been lost within the Lake Wales Ridge, and by some estimates, that number has increased to 90% lost, primarily to citrus groves. Fire suppression combined with fragmentation has disrupted historic fire regimes, which means that prescribed fires must be applied to maintain scrub vegetation to prevent it from becoming overgrown and useless for many of its specialized plants and animals.
The purpose of habitat restoration is to meet the recovery criteria for the scrub community established in the MSRP. The recovery tasks include protection of scrub habitat, management including appropriate use of prescribed fire, demographic studies to affirm the likelihood of species persistence over time, and monitoring to insure stable and sustainable populations. Management plans for scrub need to be refined to address the recovery criteria for listed plants.
The State of Florida has acquired approximately 60,000 acres on the Lake Wales Ridge for conservation and protection of the scrub ecosystem. Small, but very significant, tracts of scrub are protected on the Atlantic Coastal Ridge.
A 1999 report by the Florida Natural Areas Inventory found that several listed plants may be more widespread and abundant on conservation lands than previously thought. This and other research indicate that it is time for the FWS to assess whether threats to listed Lake Wales Ridge plants have diminished enough to warrant reclassification or delisting. The Endangered Species Act of 1973, as amended, provides that decisions to delist or to reclassify listed species be based on sufficient scientific information to assess each species relative to established recovery criteria.
What Is Known
Fire is a dominant factor in the scrub ecosystem and a crucial management tool on conservation lands. Many plants of the Lake Wales Ridge occupy sunny gaps in the vegetation that are opened and maintained by fire. During intervals between fires, shrubs encroach into these gaps. A study using experimental fire regimes has yielded useful information on how individual species and vegetation respond following fire. Research shows that fires on Lake Wales Ridge were more frequent historically than they are today; hence, there is a backlog of prescribed burning needed to restore vegetation. However, prescribed fire is not feasible on all conservation lands because of proximity to homes or other sensitive areas. Unpublished research suggests that mowing holds promise as a pretreatment to fire, but not as a substitute. Recovery from fire is a crucial aspect of the life history of every scrub plant. Ongoing plant monitoring and studies to interpret the monitoring data will help managers better understand the effects of fire on rare plants.
Other plant species, which are endemic to coastal scrub habitat, are experiencing low population numbers and continued threats. For example, the Lakela's mint is known to exist as a single population that occurs only at six isolated sites in an area one-half mile wide by three miles long in southern Indian River and northern St. Lucie Counties. The mint was listed as endangered in 1985 because of its small range and the rate at which its habitat was being destroyed. Only two of the six sites within the historic range are protected. All others are in private ownership. One of the protected sites was recently discovered, is currently suffering from habitat degradation, and contains as few as forty individuals. The other protected site received 794 plants as part of an introduction in 2002. However, the population was severely reduced to 71 individuals following Hurricanes Frances and Jeanne in September 2004. The FWS recently changed the scope of work for an existing grant to begin re-assessing and augmenting populations.
The four-petal pawpaw is an aromatic shrub found in sand pine scrub habitat. This plant was listed as endangered in 1986 because most of its habitat was being lost to urban development, which continues to be a threat to its existence. This species is also threatened by encroachment of non-native species. In a survey conducted in 2003, 1,277 plants were located in 19 sites in Martin and Palm Beach Counties. In 2005, the FWS will be funding a study to assess the impacts of Hurricanes Frances and Jeanne that made landfall in September 2004 near these populations.
What Is Needed
Population viability analyses. Population viability analyses will support reclassification decisions. These analyses, which are the preferred scientific approach to assessing a species' long-term prospects, evaluate a species' probable persistence using demographic data, information on population genetics, and a thorough evaluation of the species' life history traits, including the persistence of local populations and their sometimes fugitive local habitats. Population viability analyses contribute to the design of rare plant monitoring programs by guiding decisions on how best to distribute limited scientific resources for data collection.
A population viability analysis for wireweed was designed to help determine whether wireweed qualifies for reclassification to threatened status. Additional monitoring and synthesis of is making this analysis applicable to the species as a whole.
Population augmentation. To recover and maintain sufficient populations and genetic diversity of listed plants, these populations must be augmented and properly managed. Studies should be conducted to monitor these reintroductions and determine suitable protocols for future augmentations
Assessment of the adequacy of the conservation land network. The ambitious land acquisition projects have created a network of conservation lands for recovering the scrub ecosystem. This growing network of conservation lands needs to be comprehensively assessed to detect deficiencies that could be corrected through limited additional acquisitions and to set priorities for restoration and management. A vegetation history for Lake Wales Ridge is being developed for use in this assessment.
Research and monitoring of long-term vegetation changes following fire and/or mechanical treatments. Valuable research on the effects of fire on the life history and demography of endemic scrub plants provides guidance for additional needed research on plant demography and long-term vegetation changes following fire and mechanical treatments such as roller-chopping.
Monitoring programs that document changes in plant populations will provide a basis for assessing the effectiveness of burning regimes and the negative effects to rare plants from use of mechanized equipment in vegetation and fire management.
DOI managers also need information about patterns of dispersal and colonization of new habitat patches following fire. Papery whitlow-wort, sandlace, and several other listed plants have disappeared from large areas of scrub that became overgrown due to fire suppression and found refuge in artificially created open areas. It is important to know whether these "refugee" populations are able to recolonize new scrub habitat as it becomes available following prescribed fires.
Information about the indirect effects on scrub habitat of land management and other practices. The Florida Fish and Wildlife Conservation Commission proposes to study the effects of mowing as an alternative to prescribed fire. Other land use practices that could affect the persistence of rare scrub plants, including off-road driving, dumping, and trespass, should be evaluated to support appropriate recommendations in management plans.
Recovery of Scrub-Dependent Animals
Project Purpose and Major DOI Interest
What Is Known
It was once thought that the Highlands tiger beetle only occurred in two scrubs on the southern Lake Wales Ridge, both of which were destroyed by development. Surveys since 1992 have found new occurrences of the Highlands tiger beetle, but fewer than 1,000 individuals. Due to a lack of recent information on the species' status, the FWS funded a rangewide status survey for the tiger beetle in 2004. Specific objectives of the survey included: determining the current distribution and abundance of the tiger beetle, including adult population sizes, potential habitat, and utilized habitat at each site; estimating larval abundance and recruitment at all sites with medium to large populations; determining the threats and limiting factors to the habitat and the beetle population at each site and re-examining relevant biological characteristics of the species; and providing site-specific management recommendations for protection and recovery of the species. According to preliminary results, sites occupied by the tiger beetle during the 1996 survey are still occupied, and additional sites were found. A final report is not yet available.
What Is Needed
Except for a few locations where intensive research has been conducted, there is little definitive information about the presence, abundance, or trends of the sand skink and the bluetail mole skink. The species' diminutive sizes and secretive habits make them difficult to study. More recent studies have provided new information about their distributions, but little information is currently available to assess the species' status or trends. A risk assessment and population viability analyses will identify the number of protected sites needed to ensure a 95% probability of persistence of these two skink species over the next one hundred years. Monitoring to determine if these skink populations are stable or increasing will require development and implementation of specialized methods. As suitable habitat becomes more fragmented from development pressure, it will be necessary to explore alternatives to fire management to maintain scrub habitat and determine effects on skinks from human activities, such as pesticide use. Management prescriptions for scrub should be studied to determine the relationship between time-since-fire and the needs of skinks versus scrub-jays.
Information about the effects of land management and other practices. DOI managers need Information about how to minimize negative effects from mechanized equipment used in fire management and alternatives to fire management in small fragmented parcels where burning is not feasible. The Florida Fish and Wildlife Conservation Commission proposed to study the effects of mowing as an alternative to prescribed fire. Where monitoring data are available on lands that have been managed using prescribed fire, changes in the size and location of animal populations will be documented to assess how burning regimes may have affected these species.
Recovery of Pine Rockland Community: Miami-Dade County
Project Purpose and Major DOI Interest
Miami-Dade County's pine rocklands were largely destroyed by the time the conservation value of their tropical flora was realized. Limestone bedrock at the surface of the ground, and an understory of tropical shrubs and herbs beneath the slash pines that visually dominate this community, distinguish pine rocklands from the sandy pinelands that covered much of the rest of Florida. Historically, the pine rocklands occupied the highest ground in the Miami area, constituting upland "islands" in a predominantly wetland landscape. Much of present-day Miami and its southern suburbs were built on pine rocklands, as were most of the county's valuable farmlands. The farmlands have been "rockplowed" to produce finer-textured material that serves as soil. The largest surviving tract of pine rockland in Miami-Dade County is the 19,000-acre Long Pine Key, an island of higher ground within Everglades National Park. However, most of the listed plant species are found outside of the park, typically in small isolated tracts. Of the original 161,660 acres of pine rocklands outside of Everglades National Park, only about 1.5% remain, according to a new mapping project conducted by FWS and several of its partners.
The purpose of habitat restoration is to meet the recovery criteria for pine rockland plants, established in the MSRP. Recovery tasks include protection of pineland habitat, management including appropriate use of prescribed fire, demographic studies to affirm the likelihood of species persistence over time, and monitoring to ensure stable and sustainable populations and appropriate land management. The recovery of pine rockland plants is constrained by the limited area of habitat remaining for all but the threatened Garber's spurge. Limited but important opportunities exist to restore badly degraded pinelands or to recreate pinelands where they have been destroyed.
The surviving pine rockland habitat is adversely affected by invasive exotics and suppression of fire. Miami-Dade County has developed effective methods to kill exotic pest plants and to minimize reinfestations. Many pineland sites, including some that are relatively large, have achieved maintenance status. A program by The Nature Conservancy to persuade landscapers, nursery operators, and homeowners not to landscape with invasive plants may further decrease the threat to pinelands and native tropical hardwood forests caused by exotic plant species. A Private Stewardship Grant to the nonprofit Institute for Regional Conservation will prepare 14 privately-owned sites for prescribed fire, and train their owners in landscape maintenance to preserve and protect pine rockland habitat containing listed and imperiled species.
The C&SF Project resulted in the lowering of groundwater levels in some of the areas where native pine rocklands still persist. Several CERP projects offer limited opportunities to partially restore historic water tables to pine rocklands that were dried out by the extensive drainage system in southeastern Miami-Dade County (e.g., the Cutler Slough drainage area). However, implementation of CERP seepage management projects also has the potential to further lower the water table in some areas through seepage management projects.
What Is Known
What Is Needed
Population viability analyses. Any reclassification decisions will require population viability analyses or studies that can detect serious threats to viability. Population viability analyses are inherently labor intensive and require several years; therefore, such assessments should be conducted only when there is reason to believe that the life histories of the plants and the availability of appropriate study sites make the assessments feasible.
Natural forest community mapping. Miami-Dade County found that accurate natural forest community maps, which show both vegetation and the locations of important plant populations, are essential for management of county lands, for outreach assistance to private landowners, and for support for the county's regulations that promote the preservation of natural forest communities. The county completed an intensive 18-month mapping and inventory project, with the FWS providing GIS support. This project has provided the first truly accurate maps and will soon be expanded with mapping of important plant populations. The mapping will greatly assist the County's tax incentive program for owners of natural forest communities.
Recovery of imperiled pineland invertebrate and reptiles. South Florida has a suite of rare butterflies and tree snails, which may have been adversely affected by habitat loss, pesticide spraying, and illegal collecting. DOI lands may provide protected areas for managing rare pineland invertebrates and reptiles. Resource management activities (including hydrological alterations, prescribed fires, spraying of pesticides and herbicides, and mowing and trimming) can adversely affect these species, so requirements of these species need to be considered in restoration and management plans. Collecting information about the status and ecology of these rare animals on DOI lands will assist land managers in conducting their activities to ensure that these species are protected and conserved.
Analysis of mechanical treatment to recover habitat. Mechanical treatments, amounting to heavy-duty mowing in lieu of prescribed fire, appear to be useful when removing exotic pest plants, reducing overgrown native woody plants, or maintaining sites where prescribed fires are not feasible. Due to the proximity of development and other land uses to these habitats, the use of fire is sometimes problematic, making mowing an important alternative. Experimental treatments with assessments of results will guide future uses of this approach.
Research to support species propagation and reintroduction. Insufficient data exist to support the successful collection of native pine rockland seeds or whole plants, other than slash pine, and the successful propagation of these species. Experimental pine rockland restoration projects will guide the development of the necessary horticultural methods and infrastructure. Species-specific reintroduction methods for the endangered Carter's flax , the spurges, and several candidate species will help ensure the success of restoration efforts. In both cases, once the plants are introduced, the sites will be monitored for several years to assess the success of the introductions. Crenulate leadplant also needs introductions, but managers are already experienced with this species.
Monitoring the ecological response to rehydration. Where rehydration occurs, monitoring will assess whether the slash pines and herbaceous understory plants are benefiting as anticipated. Long-term monitoring of pine rockland plan species, especially in protected areas, is needed to provide the baseline data for comparison of changes in communities due to rehydration from CERP or to other factors stemming from human development.
Recovery of Florida Keys Species
Project Purpose and Major DOI Interest
The purpose of this project is to meet the recovery criteria for the Florida Keys species, established in the MSRP. Although the listed species rely on different habitats for their continuing survival, the recovery tasks for all the species include protecting and managing habitat, restoring potential habitat, increasing population sizes and ranges, controlling anthropogenic factors, and monitoring to ensure stable and sustainable populations.
Biscayne National Park, Crocodile Lake National Wildlife Refuge, National Key Deer Refuge, Great White Heron National Wildlife Refuge, Key West National Wildlife Refuge, and the Florida Keys Wildlife and Environmental Area, along with several state parks, support much of the remaining habitat for the endemic species. Native habitats in the Upper Keys consist of hardwood hammock, freshwater wetlands, and mangrove wetlands. Native habitats in the Lower Keys consist of hardwood hammock, pine rockland, mangrove wetlands, freshwater wetlands, and salt marsh.
The MSRP recommends augmenting wild populations of several Keys species by reintroducing animals to unoccupied suitable habitat. The plan also addresses captive breeding.
Habitat protection, restoration, and/or population augmentation may allow some species to recover to the point where reclassification or delisting will be possible.
Management plans for the conservation areas will address habitat fragmentation and degradation associated with saltwater intrusion, exotic vegetation and animals, fire suppression, and other impacts associated with human manipulation of the environment. These plans will also address the effects of human encroachment adjacent to conservation lands. For example, reluctance to reintroduce the role of fire into ecosystems bordering on developed areas may be depriving some species of a critical element of their habitat that is dependent on this disturbance event.
What Is Known
The Key Largo woodrat is an endemic species with the only known population occurring in the hammocks of north Key Largo. Based on trapping from March-September 2002, the Key Largo woodrat population was estimated at 106 individuals (with a range of 30-182 individuals) and at risk of extinction. Trapping conducted during 2003-2004 continued to indicate a declining population. Assumed threats for the Key Largo woodrat include secondary impacts as a result of development such as free-ranging cats, raccoons, black rats, and fire ants. The effects of these threats on the woodrat population are difficult to evaluate because few data are available on the abundance and distribution of these species. The magnitude of threat from each of these species on the woodrat is difficult or impossible to determine without further study.
No recent population surveys have been conducted for the Key Largo cotton mouse. Although cotton mice are captured on a regular basis during Key Largo woodrat trapping, accurate population density estimates cannot be made from the collected information. Threats to the cotton mouse are assumed to be similar to those listed for the Key Largo woodrat and efforts to minimize these threats are believed to be beneficial to both species.
Annual monitoring of the American crocodile in Florida indicate that criteria for reclassification from endangered to threatened have been achieved. In March 2005, the FWS proposed to reclassify the Florida distinct population segment of the American crocodile from endangered to threatened. The number of crocodiles known to nest in south Florida has more than doubled since 1975. Most nesting sites in north Key Largo are the result of dredge and fill activities which require annual maintenance to prevent their degradation. Of the currently known nesting location nests on Crocodile Lake National Wildlife Refuge are most likely to fail as the result of desiccation.
Preferred habitat of the Schaus swallowtail butterfly includes hardwood hammocks in the Upper Keys, which suffered a direct hit from hurricane Andrew in 1992. The FWS sponsored a captive breeding program that helped Schaus populations recover and expand through the mid-1990s, although more recent surveys show declining numbers. Habitat loss, pesticide use, and over collecting are the primary causes for this species' decline. Hammock fragments are increasingly rare in the Upper Keys as a result of development activities, making preservation of the remaining large contiguous forest fragments essential.
The Stock Island tree snail is virtually absent from its historic range on Stock Island and Key West. The primary threats to the conservation of the snail include loss of habitat from development, application of pesticides, fragmentation of habitat, and predation by black rats and exotic fire ants. Populations of the snails were established at six locations outside of its historical range; however, surveys indicate continued threats and declines at most of those locations.
Habitat destruction has limited the Lower Keys marsh rabbit to small populations on a few keys. Population estimates range between 100 and 300 rabbits. The majority of the remaining habitats are isolated from each other by urban areas, and population interchange seems unlikely. A population viability analysis conducted for the rabbit predicted that this species may become extinct in 20 to 30 years. The rabbit is threatened by habitat alteration, contaminants, road mortality, poaching, domestic animal predation, , exotic fire ants, and exotic vegetation. Woody encroachment by native trees, as well as exotic species, is occurring within many existing habitat patches
The rice rat occurs in freshwater and tidal wetlands on several islands in the Lower Keys. This species requires large, intact marsh systems. A large amount of occupied rice rat habitat is protected through public acquisition and management, but significant areas remain in private ownership. The conservation of the rice rat may be adversely affected by construction activities for residential and commercial development, mangrove trimming, and impacts to natural hydrologic cycles due to fill roads, borrow pits, and mosquito ditches.
The Key deer's population is increasing due to prohibitions on hunting, habitat management, and habitat protection. There is, however, a contraction in the range of Key deer, which may be at or near ecological carrying capacity. In May 2003 the FWS initiated a plan to augment deer on sparsely populated keys by moving selected deer from their more densely populated core areas. Current threats include habitat loss and degradation from development, fencing, fire suppression, invasive exotic plants, lack of freshwater, density-dependent disease, and road mortality.
The Key tree-cactus occurs on several Keys ranging from Upper Matecumbe to Big Pine. The Big Pine Key population, occurring within the National Key Deer Refuge, is much larger than the others. The species inhabits low elevation hardwood hammock and may be particularly susceptible to sea-level rise and salt-water intrusion. During 2004, a decline phenomenon was detected. By spring 2005, a massive die-off had occurred throughout the range, including Big Pine Key. Potential causes include exotic pathogens, high salinity levels, and competition with hardwoods following maturation of hammock stands. The complex suite of stressors has likely brought about the decline.
What Is Needed
Determine how the secondary effects of development are affecting the threatened and endangered species of the Keys. Further research is needed to determine the degree to which secondary effects of development are impacting listed species. Assessing the status of and impact on listed species by free-ranging cats, raccoons, blacks rats, fire ants, and potentially other non-native or other over-abundant species is needed. Although land in north Key Largo was set aside for the various threatened and endangered species this only addresses one of the threats (i.e. habitat loss) that contributes to the decline of many of these listed species. Because the refuge and state botanic sites are surrounded by large developments (and contain private inholdings), active management is required to maintain these areas as suitable habitat. A long-term plan for address secondary effects from development needs to be developed and implemented.
Analysis of life history requirements. The fact that many species continue to decline despite protection indicates the need to assess the genetic consequences of small population size and how human activities adjacent to conservation lands might be adversely affecting population sizes. Determinations of whether sufficient habitat for listed species has been protected, and whether the current protective management strategies are adequate, will require knowledge of the life history requirements and the status of each species, both on and off conservation lands.
Many Keys species depend on hardwood hammocks for their survival. Management of the remaining hammocks has largely focused on maintaining mature hammock vegetation and the removal of exotic vegetation. An adaptive management approach needs to be taken to determine how habitat manipulation within some of these areas may benefit the threatened and endangered species occupying these areas.
Determine the preferred method of habitat manipulation to improve the survival of the Key Largo woodrat in north Key Largo. The once typical stick nests of the Key Largo woodrat have all but disappeared in north Key Largo. Many of the stick nests are now located in rock piles resulting from dredging or proposed developments or in debris piles that were illegally dumped on abandoned roads. Whether we can mimic the rock piles and/or debris piles and whether they will be utilized by the woodrat needs to be determined.
Research to determine individual species' responses to fire. Studies of species' responses to fire are needed not only in the pine rockland community but throughout the entire upland and transitional area landscape of the Keys. The role of fire in maintaining habitats of the Key deer and Lower Keys marsh rabbit needs to be investigated. Further analysis of this kind will help identify where natural disturbance regimes should be restored, and where other measures for maintaining communities, such as hardwood hammock communities in the vicinity of pine rocklands, should be investigated to protect species that are not fire tolerant.
Analysis of minimum habitat requirements for species introduction. Before reintroducing animals to unoccupied habitat, it is important to define and understand their minimum habitat requirements, patterns of dispersal, and whether enough suitable habitat exists to support a population.
Population augmentation will be monitored to determine the long-term viability of translocated populations and to ensure that restored habitat remains suitable and that translocated animals remain within the expanded range.
Monitoring and biological status assessments. Ongoing monitoring of habitats,populations , and population correlates throughout each species' historic range, and comparison of findings with the recovery criteria listed in the MSRP, will guide determinations of changes in species' status and when recovery goals are achieved.
U.S. Department of the Interior, U.S. Geological Survey
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