Cape Sable Seaside Sparrow Research Articles

Genetic analysis of federally endangered Cape Sable seaside sparrow subpopulations in the Greater Everglades, USA

The federally endangered Cape Sable seaside sparrow (Ammospiza maritima mirabilis) is endemic to the Greater Everglades ecosystem in southern Florida, inhabiting fragmented marl prairies in six individual subpopulations. The subspecies is threatened by loss of breeding habitat from fire and water management. Genetic information is severely limited for the subspecies but could help inform decisions regarding subpopulation protections and potential translocations for genetic rescue. To provide genetic data and inform management efforts, feather samples were collected across five subpopulations (designated A–E) and protocols were tested to optimize DNA extraction yields. We assessed four mitochondrial DNA markers (N = 36–69) and 12 nuclear microsatellite loci (N = 55) in 108 sparrows. Mitochondrial DNA sequences revealed low haplotype diversity, with NADH dehydrogenase-2 haplotypes matching to most other extant subspecies and to the Atlantic coast subspecies. Nuclear diversity was low compared to other subspecies, but similar across subpopulations. Samples grouped as one population when analyzed by Principal Component Analysis, Bayesian modelling and genetic distance metrics. Limited genetic emigration was detected from one putative migrant. Relatedness was significantly different for sparrows in the most geographically distant subpopulation (A), likely reflecting high self-recruitment and natal site fidelity (P = 0.003). The low to moderate effective population size (NE = 202.4; NE:NC = 0.06) and generation time estimates indicated that unique genetic variation could be lost quickly during stochastic events. The sample sizes were limited, which reduced the power to comprehensively address recent population size reductions and any subsequent loss of genetic diversity.

The Importance of Paleoecology in Everglades Restoration Science and Management

Paleoecology studies provide pre-instrument data from the Everglades painting an informative picture of physical, biological, and ecological conditions prior to human intervention. Because Florida’s development history is relatively recent, and because observational data span only the last half-century, managers rely on paleoecology data as the basis for important decisions regarding multi-decadal and expensive restoration. Effective restoration depends strongly on the establishment of restoration targets, especially pre-development vegetation and hydropatterns (flow, depth, timing, distribution). Coring data were instrumental in the reconstruction of paleo hydrologic and vegetation trends in the ARM Loxahatchee National Wildlife Refuge, helping managers understand the magnitude and causes of 20th century problems. Similarly, sediment cores from the Big Cypress National Preserve led managers to understand that the development of marl prairies in Everglades National Park – critical habitat for the endangered Cape Sable Seaside Sparrow – was a 20th century phenomenon resulting from past water management practices. Finally, paleoecological and modeling studies in Florida Bay and the Everglades for the $20B+ Comprehensive Everglades Restoration plan established freshwater flow targets now used by managers. Although restoration of historic freshwater flow is not feasible, knowledge about Everglades hydrology and ecology prior to human intervention plays a pivotal role in the design, selection, and construction of restoration projects. Paleoecological data, coupled with decadal-scale monitoring and other long-term studies, provide the long-term perspective necessary to understand decadal, to centennial, and to millennial time-scale processes. While these data are cost-effective to procure, a long-term commitment to funding these types of studies is essential to provide the scientific foundation for restoration.

Sea level rise may pose conservation challenges for the endangered Cape Sable seaside sparrow

Biodiversity conservation under a changing climate is a challenging endeavor. Landscapes are shifting as a result of climate change and sea level rise but plant communities in particular may not keep up with the pace of change. Predictive ecological models can help decision makers understand how species are likely to respond to change and then adjust management actions to align with desired future conditions. Florida’s Everglades is a wetland ecosystem that is host to many species, including a large number of endangered and endemic species. Everglades ecosystem restoration has been ongoing for decades, but consideration of sea level rise impacts in restoration planning is more recent. Incorporating potential impacts from sea level rise into restoration planning should benefit species and their coastal habitats, most notably at the southern Florida peninsula. The endangered Cape Sable seaside sparrow (Ammospiza maritima mirabilis) occurs in marl prairie habitat at the southern end of the Everglades. The locations of three of its six subpopulations are proximate to the coast. We used a spatially explicit predictive model, EverSparrow, to estimate probability of sparrow presence considering both hydrologic change from restoration and sea level rise. We found that the probability of sparrow presence decreased with increasing sea level rise. Within approximately 50 years, probability of presence significantly decreased for all three coastal subpopulation areas, with areas above 40% probability increasingly limited. Given the exceptionally low dispersal ability of this species and the geographic restrictions for habitat expansion, our results highlight the importance of freshwater flow into the southern Everglades marl prairie for habitat conservation.

Endangered Cape Sable seaside sparrow ecology: actions towards recovery through landscape-scale ecosystem restoration

Understanding the ecology of endangered taxa and the factors affecting their population growth and decline is imperative for their recovery. In the southeastern USA, the Everglades wetland ecosystem supports a high diversity of species and communities, including many endemic and imperiled taxa, such as the federally endangered Cape Sable seaside sparrow Ammospiza maritima mirabilis (CSSS). The Everglades, once a completely connected wetland with a slow-moving sheet flow of water, is now compartmentalized into separated wetland units where water distribution is managed year-round. The CSSS is affected by, and at the crux of, many Everglades ecosystem restoration decisions. The CSSS faces conservation challenges, including limited habitat availability, low population numbers, dispersal limitations, and constraints on suitable breeding conditions owing to wetland water levels. Despite these challenges, ecological knowledge of the factors affecting CSSS population numbers in the context of ongoing ecosystem-level restoration can help inform protection of this bird while restoring the Everglades. Existing research shows target hydroperiods between 90 and 210 days, a minimum of 90 consecutive dry days during the breeding season, and non-breeding season fires approximately every 5-10 years may aid in CSSS recovery. There are numerous tools and models to support habitat and water management for the CSSS, and the most recent ecosystem-level water operations plan for the Everglades indicates potential for increased CSSS habitat. Here, we provide a review on the ecology of the CSSS, factors affecting population decline, and ecosystem-level restoration actions that may aid in CSSS recovery.

Landscape-scale drivers of endangered Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis) presence using an ensemble modeling approach

The Florida Everglades is a vast and iconic wetland ecosystem in the southern United States that has undergone dramatic changes from habitat degradation, development encroachment, and water impoundment. Starting in the past few decades, large restoration projects have been undertaken to restore the landscape, including improving conditions for threatened and imperiled taxa. One focus of restoration has been the marl prairie ecosystem, where the federally endangered Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis; CSSS) resides. The CSSS is endemic to the Everglades where populations have been steadily declining, signaling the importance of decision support tools for natural resource managers for evaluating water management and restoration scenarios. Here we developed an ensemble logistic regression, combining a frequentist and Bayesian approach, to model CSSS presence and measure how environmental factors such as hydrometrics, fire occurrence, and vegetation structure impact CSSS habitat suitability. This is the first analysis to quantitatively assess the interdependent relationships between a broad range of environmental factors and CSSS presence across the landscape. Our results show that the probability of CSSS presence was highest in areas with dry conditions, hydroperiods between 80 and 120 days, percentages of canopy cover and woody vegetation less than 10%, and more than six years post-fire where 75% or more of the area was burned. Because the frequentist and Bayesian models had nearly identical spatial outputs with the Bayesian model having slightly higher validation metrics, we used the Bayesian approach as our final model (EverSparrow). The results from our analysis can provide a valuable decision support tool as natural resource managers work to restore the Everglades landscape.

Interpreting Smoke Signals: Fire Ecology and Land Management for Four Federally Listed Birds

Recovery of listed species requires that land managers and research biologists work together to address the factors affecting population stability and growth. In Florida, an essential factor affecting rare species habitat quality and restoration is fire management. Fire plays an essential role in restoring and maintaining almost every upland ecosystem in Florida, but fires also have negative effects (e.g., mortality and displacement) that play out today within an altered landscape where rare species are often limited to small, fragmented areas and negative effects may be accentuated. Fire effects also are complex, not well studied experimentally, and likely to change as urbanization and global temperatures increase over coming decades. These conditions can create missteps in both fire research and fire management without regular communication between scientists and practitioners. We assessed the fire-related research associated with 4 federally listed birds in Florida: Cape Sable seaside sparrow (Ammodramus martimus mirabilis), Florida grasshopper sparrow (A. savannarum floridanus), Florida scrub-jay (Aphelocoma coerulescens), and red-cockaded woodpecker (Dryobates borealis). Fire research has not addressed the needs of some of these species for starkly different reasons. Land managers, in turn, have not successfully applied the recommendations of fire research in other instances. Our results point to fire frequency as an important focus for practitioners managing habitat for rare species in Florida. Our review also suggests that successful integration of research and management will be best served when (1) ecological burning practices are used, (2) local fire management goals are prioritized annually, (3) instructional products are developed for managers, (4) land manager tenure is promoted, (5) stakeholders meet regularly, and (6) creative solutions are devised to overcome staff and equipment shortages.

Fire disturbance influences endangered Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis) relative bird count

AbstractPeriodicity of fire disturbance is a known driver of ecosystem function and is reported as important in both promoting and maintaining viable breeding habitat for the endangered Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis; CSSS). In south Florida, the CSSS serves as a fine‐scale indicator of the marl and mixed‐marl prairie communities of the Florida Everglades. The CSSS distribution is affected by numerous well‐documented physical drivers, including water depth and fire regime. Here, we fit zero‐inflated negative binomial generalized linear mixed models and used model selection to determine the relationship between CSSS bird count observations from 1992 to 2014 and the spatially‐specific fire return interval on the landscape. CSSS bird count was highest at a 5–8‐year fire return interval and increased linearly with the percent of cell burned (400 × 400 m cells). The results of this study can inform management plans designed to maintain existing, and promote new, marl prairie habitat for conservation of the CSSS.

Recurrence intervals of spatially simulated hydrologic metrics for restoration of Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) habitat

Marl prairie, a diverse graminoid-dominated freshwater vegetation community in the Florida Everglades, provides a specialized niche for the federally endangered Cape Sable seaside sparrow (CSSS). This paper describes a regional habitat suitability modeling approach to evaluating how changes in management from Everglades restoration may affect the CSSS. The Cape Sable Seaside Sparrow Marl Prairie Indicator (CSSSMarlPrairie) is a spatially explicit model that integrates frequency (return periods) of target hydrologic conditions to simulate the anticipated response of marl prairie CSSS habitats to fluxing hydropatterns resulting from restoration projects, water management operations, and climatic change. The model integrates CSSS field survey data with the hydrologic targets at the resolution of the hydrologic simulation model (in this case, the Regional Simulation Model). The application of return periods for hydrologic events provides a novel approach for simulation of anticipated marl prairie responses in the southern Everglades and is readily applicable to evaluating targets of modeled wetland restoration scenarios elsewhere. CSSSMarlPrairie is intended to be used for decision support, in association with a suite of ecological models for additional species of management concern, to facilitate planning of ecosystem restoration projects such as those in the Comprehensive Everglades Restoration Plan and recovery of the marl prairie habitats of the CSSS. A tentatively selected restoration plan for the central Everglades is projected to have mostly minor overall impacts to marl prairie CSSS habitats. Local substantial habitat shifts in and adjacent to designated habitat boundaries have been identified, however, that warrant management consideration.

Effectiveness of Artificial Song Playback on Influencing the Settlement Decisions of an Endangered Resident Grassland Passerine

Abstract. Social information in the form of songs, calls, or other overt behaviors may assist birds in assessing the quality of potential breeding habitat by providing direct public information about a site's quality or by providing indirect cues (e.g., the presence of conspecifics) that may be used to infer its quality. Broadcast of song has been used to demonstrate the influence of conspecific cues on the decisions of migratory passerines to settle; however, there is currently a dearth of information regarding resident species. We tested the influence of conspecific attraction and the effectiveness of song playback on an endangered resident of grassland, the Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis). We broadcast recorded song over large areas of suitable breeding habitat in the Florida Everglades in an attempt to influence the settlement of male sparrows during territory establishment. Our analyses included the creation of a qualitative sound map that formed a basis for measuring the ...

A new approach to the “apparent survival” problem: estimating true survival rates from mark–recapture studies

Survival estimates generated from live capture-mark-recapture studies may be negatively biased due to the permanent emigration of marked individuals from the study area. In the absence of a robust analytical solution, researchers typically sidestep this problem by simply reporting estimates using the term "apparent survival." Here, we present a hierarchical Bayesian multistate model designed to estimate true survival by accounting for predicted rates of permanent emigration. Initially we use dispersal kernels to generate spatial projections of dispersal probability around each capture location. From these projections, we estimate emigration probability for each marked individual and use the resulting values to generate bias-adjusted survival estimates from individual capture histories. When tested using simulated data sets featuring variable detection probabilities, survival rates, and dispersal patterns, the model consistently eliminated negative biases shown by apparent survival estimates from standard models. When applied to a case study concerning juvenile survival in the endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis), bias-adjusted survival estimates increased more than twofold above apparent survival estimates. Our approach is applicable to any capture-mark-recapture study design and should be particularly valuable for organisms with dispersive juvenile life stages.

Too few data and not enough time: approaches to detecting Allee effects in threatened species

The detection of Allee effects is critical in assessing extinction risk, but is extremely difficult when sampling small, low-density populations. Failure to detect true Allee effects could lead to overoptimistic assessments of threat status, as well as the development of inappropriate species recovery plans. We outline a broadly applicable approach for evaluating Allee effect likelihood in analyses of sparse demographic data, explicitly acknowledging the uncertainties associated with detecting subtle Allee effects among the suite of factors that can influence demographic variability. Detailed information on the probability of Allee effects will empower conservation decision makers to balance extinction risks against the political and economic costs associated with management action. We use an illustrative case study involving demographic analyses of the endangered Cape Sable seaside sparrow, highlighting the value of information on Allee effect likelihood for the development of restoration measures within species recovery plans.

Variation in Laying Date and Clutch Size: the Ev erglades Environment and the Endangered Cape Sable Seaside Sparrow (Ammodramus Maritimus Mirabilis)

ABSTRACT . When to commence breeding is a fundamental decision made by individuals that inhabit seasonal environments. Although photoperiod determines the timing of breeding in most temperate zones, other abiotic conditions can also play a significant role by influencing food availability and, consequently, reproductive performance throughout a breeding cycle. This study used the multibrooded endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis) to test whether water conditions (rainfall and groundwater levels) influenced breeding variables in a subtropical environment, the Florida Everglades. Timing of breeding was related to rainfall preceding the breeding season, with females initiating nesting up to 1 month earlier in years with greater rainfall. Clutch size averaged 3.4 eggs, and females showed an increase in clutch size as the breeding season progressed and in response to higher groundwater levels during the laying period. This effect was more apparent for first nesting attempts, wi...

Importance of estimating dispersal for endangered bird management

AbstractEndangered species recovery plans are frustrated by small, spatially structured populations where understanding the influence of birth, death, and dispersal is difficult. Here we use a spatially explicit, long‐term study to describe dispersal in the Cape Sable seaside sparrow (Ammodramus maritimus mirabilis). Since 1990, this species declined > 50%. It occurs as several geographically isolated subpopulations in the Florida Everglades. We characterize dispersal, recognizing that our sampling, as well as the species’ distribution, is spatially heterogeneous. The annual movements of juveniles and adults are statistically heavy‐tailed. That is, while most individuals are recaptured locally, a significant portion exhibit long‐distance dispersal. Individuals move between subpopulations to distances >30 km. Not accounting for the spatial heterogeneity of sampling or the species range itself underestimates dispersal and can lead to ineffective management decisions. Recovery focused on translocation will be less successful than strategies that protect habitat and increase breeding.

Endangered Cape Sable Seaside Sparrow Survival

ABSTRACT We investigated survival for male, female, and first‐year Cape Sable seaside sparrows (Ammodramus maritimus mirabilis, hereafter sparrows), a federally endangered bird restricted to the Florida Everglades, USA. Accurate estimates of survival are critical to improve management decisions and population estimates for this and other threatened species. We used Program MARK to evaluate effects of age, sex, population membership, temporal variation, and ground‐water levels on annual survival from mark‐recapture data collected across 3 sparrow populations from 1997 to 2007. We found little evidence that annual survival rates differed between the populations or across ground‐water levels, but we found high variability between years for both adult and juvenile survival. Our results revealed female sparrows experienced 14–19% lower survival than males. Sparrows experienced much lower survival during their first year of life and were short‐lived (2–3 yr). Our results highlight sparrows' susceptibility to population declines and suggest that management actions aimed at increasing survival may be effective for this species' management.

Influence of water depth on nest success of the endangered Cape Sable seaside sparrow in the Florida Everglades

AbstractThe restoration of the Florida Everglades rests largely on the ability of managers to re‐create a more natural hydrologic regime throughout the remaining natural areas. The Cape Sable seaside sparrow, an endangered subspecies endemic to the freshwater marl prairies of the Everglades, has suffered from changes in the depth and the timing of water flows through its habitat. However, it remains unclear what temporal and spatial aspects of water inputs (both managed and natural) affect nesting success. We monitored 429 nests in two of the six extant sparrow subpopulations over 10 breeding seasons and a variety of water levels. Using an information‐theoretic approach, we find that nests initiated early in the breeding season experience substantially higher success rates than those initiated later. We suggest that this seasonal effect is due to a change in predator abundance or activity levels as the season progresses, which are tied to the increase in water levels that accompany the onset of the wet season. In addition, nest success is influenced to a lesser degree by where sparrows choose to nest across the landscape, the height of base water levels within the sparrow's breeding season and the height of water levels when nests are active. Our observation of extreme variability in nest success over the span of a single season suggests that successful late‐season breeding, although shown to be important for population recovery, is a rare event. Management actions that maximize the success of late‐season broods or increase the number of early broods are warranted, but the ecosystem implications of such actions are poorly understood.

A quantile count model of water depth constraints on Cape Sable seaside sparrows

1. A quantile regression model for counts of breeding Cape Sable seaside sparrows Ammodramus maritimus mirabilis (L.) as a function of water depth and previous year abundance was developed based on extensive surveys, 1992-2005, in the Florida Everglades. The quantile count model extends linear quantile regression methods to discrete response variables, providing a flexible alternative to discrete parametric distributional models, e.g. Poisson, negative binomial and their zero-inflated counterparts. 2. Estimates from our multiplicative model demonstrated that negative effects of increasing water depth in breeding habitat on sparrow numbers were dependent on recent occupation history. Upper 10th percentiles of counts (one to three sparrows) decreased with increasing water depth from 0 to 30 cm when sites were not occupied in previous years. However, upper 40th percentiles of counts (one to six sparrows) decreased with increasing water depth for sites occupied in previous years. 3. Greatest decreases (-50% to -83%) in upper quantiles of sparrow counts occurred as water depths increased from 0 to 15 cm when previous year counts were 1, but a small proportion of sites (5-10%) held at least one sparrow even as water depths increased to 20 or 30 cm. 4. A zero-inflated Poisson regression model provided estimates of conditional means that also decreased with increasing water depth but rates of change were lower and decreased with increasing previous year counts compared to the quantile count model. Quantiles computed for the zero-inflated Poisson model enhanced interpretation of this model but had greater lack-of-fit for water depths > 0 cm and previous year counts 1, conditions where the negative effect of water depths were readily apparent and fitted better with the quantile count model.

Hydrology, habitat change and population demography: an individual‐based model for the endangered Cape Sable seaside sparrow Ammodramus maritimus mirabilis

Summary Habitat destruction and fragmentation have led to precipitous declines in a number of species of concern. For these species, traditional models that group individuals into age or stage cohorts may not accurately capture the stochasticity associated with small populations. Additionally, traditional models do not explicitly incorporate landscape‐level structure, which becomes increasingly important at small population sizes. Thus, for declining species, spatially explicit individual‐based models (SEIBM) can be used to understand both population demography and the impacts of habitat destruction, and to guide management practices to increase the chances of species survival. To gauge the impacts of changes in habitat and also demographic rates on a US endangered species, we constructed an SEIBM for the Cape Sable seaside sparrow (Ammodramus maritimus mirabilis Howell) of the South Florida Everglades. The model simulates temporal and spatial dynamics of individual sparrows using local GIS‐based topography, vegetation and hydrology along with behavioural and demographic rates derived from field studies. When adult mortality and, to a lesser extent, juvenile mortality were increased in model simulations, there was an increase in extinction risk and a decrease in population size, whereas changes in number of clutches or female mating range had little impact. In contrast to the effects of simulating changes in mortality rates, simulated landscape‐level changes (increasing water levels or decreasing habitat availability) were associated with dramatic population declines and increases in extinction risk. The sparrow appears to be particularly sensitive to the loss of higher‐elevation breeding habitat. These results highlight the importance of proper water‐ and land‐use management in assuring the species’ survival. Synthesis and applications. Although changes in demographic rates affect population growth and are often the focus of conservation efforts, changes in habitat structure can also dramatically alter population viability. When both landscape‐level and demographic data are available, spatially explicit models are particularly advantageous. Not only do they allow researchers and resource managers to prioritize areas for habitat restoration and species management, but they can also be used to help focus future research efforts.

Using long-term occupancy information to inform the management of Cape Sable seaside sparrows in the Everglades

Wildlife managers must find ways of detecting meaningful shifts in population size or extent if they are to effectively implement recovery programs for threatened and endangered species. This task is made difficult by the oft-flawed survey information to which they have access. Here we describe such a situation for the Cape Sable seaside sparrow, an Everglades endemic. An unusually long-term survey has been conducted across this subspecies’ entire range, however extracting abundance information from this survey has proven difficult and controversial. Here we treat the information contained in the survey as presence–absence data and evaluate occupancy trends through time. We also evaluate the probability that each survey site has been effectively abandoned by sparrows and the manner in which site utilization varies through time and across space. Our results indicate that Cape Sable seaside sparrows have experienced two episodes of occupancy declines. Two subpopulations continue to decline in occupancy to the present, and only one shows a consistent upswing. In accordance with these trends, we also show that the two populations that have a decreasing trend in occupancy also hold the vast majority of sites that have been abandoned by sparrows. Finally, we show a dynamic pattern of site utilization when sparrow occupancy is low and a coalescence of site usage as occupancy increases. Overall our results confirm previous proclamations of severe decline in the Cape Sable seaside sparrow numbers and argue for continued vigilance in ensuring no further reductions. We also illustrate how presence–absence information can be used to extract quite detailed information on changes in habitat occupancy and site usage that are highly relevant to managers.

Endangered species management requires a new look at the benefit of fire: The Cape Sable seaside sparrow in the Everglades ecosystem

Although disturbance processes play important roles in maintaining habitat heterogeneity, the potential effects of such processes on rare or endangered species is virtually unknown and difficult to test. We use an unplanned fire, which burned half of a long-term study plot, as a natural experiment to test the effects of fire on the federally endangered Cape Sable seaside sparrow in Everglades National Park. By implementing a before-after-control-impact study design we determine the mechanistic link between fire and demography of this endangered sparrow. Our results show that while the sparrow tolerates fire, neither sparrow density nor nesting success are enhanced by fire, which runs contrary to the current paradigm in which sparrows are expected to benefit and therefore require fire for persistence. Our results caution against the assumption that occupancy of disturbance-prone habitat automatically suggests dependence on disturbance. Land managers must prevent large and frequent fires from burning occupied sparrow habitat to best manage for the species. Moreover, it is imperative that more studies focus on the effects of disturbance processes on rare and endangered species in order to prevent further loss of biodiversity.

Southern marl prairies conceptual ecological model

About 190,000 ha of higher-elevation marl prairies flank either side of Shark River Slough in the southern Everglades. Water levels typically drop below the ground surface each year in this landscape. Consequently, peat soil accretion is inhibited, and substrates consist either of calcitic marl produced by algal periphyton mats or exposed limestone bedrock. The southern marl prairies support complex mosaics of wet prairie, sawgrass sawgrass (Cladium jamaicense), tree islands, and tropical hammock communities and a high diversity of plant species. However, relatively short hydroperiods and annual dry downs provide stressful conditions for aquatic fauna, affecting survival in the dry season when surface water is absent. Here, we present a conceptual ecological model developed for this landscape through scientific concensus, use of empirical data, and modeling. The two major societal drivers affecting the southern marl prairies are water management practices and agricultural and urban development. These drivers lead to five groups of ecosystem stressors: loss of spatial extent and connectivity, shortened hydroperiod and increased drought severity, extended hydroperiod and drying pattern reversals, introduction and spread of non-native trees, and introduction and spread of non-native fishes. Major ecological attributes include periphyton mats, plant species diversity and community mosaic, Cape Sable seaside sparrow (Ammodramus maritimus mirabilis), marsh fishes and associated aquatic fauna prey base, American alligator (Alligator mississippiensis), and wading bird early dry season foraging. Water management and development are hypothesized to have a negative effect on the ecological attributes of the southern marl prairies in the following ways. Periphyton mats have decreased in cover in areas where hydroperiod has been significantly reduced and changed in community composition due to inverse responses to increased nutrient availability. Plant species diversity and community mosaics have changed due to shifting gradients to more terrestrial or more aquatic communities, displacement of native communities by non-natives, expansion of woody plants, high-intensity dry season fires, tree-island burnout, and reduced microtopography resulting from alligator population decline. Cape Sable seaside sparrow populations are threatened by nest destruction resulting from extended hydroperiods, drying pattern reversals, and high intensity dry season fires, as well as by the expansion of woody plants into graminoid wetland habitats. Populations of marsh fishes and associated aquatic fauna that constitute the aquatic prey base for higher vertebrates have decreased in density and changed in species composition and size structure due to loss of wetland spatial extent, shortened hydroperiod, increased drought severity, loss of aquatic drought refugia in solution holes and alligator holes, and spread of exotic fishes. American alligator populations have declined in the Rocky Glades, and alligator holes have filled with sediment, as a result of shortened hydroperiod and increased drought severity. Habitat options for wading birds to forage during the early dry season and during unusually wet years have been reduced due to loss of spatial extent and shortened hydroperiod.