Marsh Birds Research Articles

Secretive Marsh Bird Densities and Habitat Associations in the Prairie Pothole Region

After centuries of wetland modification, wetland-dependent wildlife are of high conservation concern. Particularly important are secretive marsh birds, a cryptic and understudied guild of wetland-dependent birds, many of which have experienced population declines concurrent with anthropogenic modification of wetlands. We used point-based sampling to investigate densities and habitat associations of secretive marsh birds at multiple spatial scales in the Prairie Pothole Region of North Dakota. We focused on five species for modeling. The most abundant species was Virginia Rail (Rallus limicola; 0.20 individual-ha SE = 0.04), followed by Sora (Porzana carolina; 0.13 individual-ha SE = 0.02), American Coot (Fulica americana; 0.08 individual-ha SE = 0.02), American Bittern (Botaurus lentiginosis; 0.07 individual-ha SE = 0.03), and Pied-billed Grebe (Podilymbus podiceps; 0.06 individual-ha SE = 0.01). Densities of all species were best explained by multi-scale models. Despite a few commonalities, secretive marsh birds have diverse habitat requirements and models suggest species-specific wetland complex management will likely be most effective. This information provides a baseline for species with previously unknown densities and informs conservation actions and policy for secretive marsh birds in the northern Great Plains.

Coastal Marsh Bird Habitat Selection and Responses to Hurricane Sandy

Wetlands provide numerous ecosystem functions such as water purification, nutrient cycling, and wildlife habitat. Avian populations are indicators of wetland health, and understanding their responses to extreme events can aid in targeting restoration efforts following disturbance. Here, we assessed the habitat selection of six coastal wetland bird species (American Bittern, Black-crowned Night Heron, Great Egret, Glossy Ibis, Snowy Egret, Yellow-crowned Night Heron) related to an extreme weather event, Hurricane Sandy. We used Discrete Choice Resource Selection Functions to estimate habitat selection. Results showed species probability of use increased with lower elevation and slope, and closer proximity to marsh, salt marsh, Phragmites, and protected areas. Estimates of marsh dieback from Hurricane Sandy occurred disproportionately in areas with higher probability of species use. Species were observed farther from the coast and at higher elevations in the four breeding seasons after (2013–2016) compared to before (2000–2012) Hurricane Sandy. Our results indicate that although high suitability areas were affected by the storm, these six wetland bird species may have responded by moving inland and to higher elevation. Understanding how coastal wetland birds respond to storm events is important for conservation planning, particularly as storm frequency is projected to increase in the future.

Using visualization and machine learning methods to monitor low detectability species—The least bittern as a case study

Long duration acoustic monitoring is becoming an increasingly popular approach to extend survey effort by using autonomous sensors to passively collect data over large temporal and spatial scales. This is of particular benefit when attempting to detect a species whose temporal vocalization strategy is unknown, and whose small population size reduces detection probability. It is also of benefit in environments that are logistically difficult to access such as wetlands. We investigated the vocalization strategy of the Least Bittern (Ixobrychus exilis), a species of high conservation concern in the Western hemisphere and ‘in need of management’ in multiple states of the USA. The Least Bittern is a secretive marsh bird that is primarily detected by its vocalizations and call-playback surveys are typically used for population monitoring. To minimize disturbance to both the birds and their habitat, we deployed autonomous acoustic recording units and collected continuous 24-hour audio recordings for 30 days. The resultant accumulation of data necessitated an automated method to assist with analysis and interpretation. We successfully applied a novel soundscape technique—long-duration, false-color (LDFC) spectrograms—to visually confirm presence of Least Bittern from the ‘coo coo coo’ vocalization associated with breeding. In addition, we used a machine learning technique to automate the acoustic event detection process. Peak vocalization times were then predicted from an annotated dataset of actual calls and subsequently used to develop an optimal acoustic survey strategy. The results of this research demonstrate how machine learning methods can search large data sets for a specific species. This information can then be used to optimize existing monitoring methods, to increase detection probability and to minimize associated costs.

Predictive multi‐scale occupancy models at range‐wide extents: Effects of habitat and human disturbance on distributions of wetland birds

AbstractAimPredicting distributions is fundamental to ecology, yet hindered by spatially restricted sampling, scale‐dependent relationships and detection error associated with field surveys. Predictive species distribution models (SDMs) are nonetheless vital for conservation of many species. We developed a framework for building predictive SDMs with multi‐scale data and used it to develop range‐wide breeding‐season SDMs for 14 marsh bird species of concern.LocationUSA.MethodsWe built SDMs using data from range‐wide surveys conducted over 14 years, and habitat and disturbance covariates measured at multiple spatial scales. We built hierarchical occupancy models that included heterogeneity in detectability during sampling, and used Bayesian model selection to regulate model complexity (covariates and scales) based explicitly on spatial predictive abilities. We thus integrated model selection for optimizing out‐of‐sample prediction, range‐wide sampling over broad conditions, multi‐scale analyses and scale optimization, and species‐specific detectability for a suite of wide‐ranging species.ResultsDistributions of marsh birds were affected by local wetland conditions, but also by agricultural, urban and hydrologic disturbances operating from local scales (100–500 m) to the watershed level. Variables measuring human disturbances improved prediction for most species, and every species was affected by attributes at >1 scale. Five species showed evidence for continental‐scale range contraction during the study.Main conclusionsWe demonstrate how hierarchical occupancy models can be optimized for prediction across a species' range at the extent of a continent while also accounting for imperfect detection, and thus describe a generalizable approach that can be used for any species. We provide the first data‐driven, empirical SDMs built at the range‐wide extent for most of our 14 study species and demonstrate that previous studies focused on local distributions and the effects of fine‐scale wetland vegetation missed important broadscale drivers of occupancy for marsh birds.

Identifying important military installations for continental-scale conservation of marsh bird breeding habitat

Degradation of wetland ecosystems has negatively impacted many species, perhaps none more so than marsh birds that breed in vegetative emergent wetlands throughout North America. The U.S. Department of Defense manages approximately 29 million acres of land within the continental U.S., and many military installations contain wetland complexes that may be important for wetland birds. Thus, failure to adequately manage habitat for marsh birds could result in species extirpations and additional listings under the Endangered Species Act, and may result in regulatory burdens that reduce military readiness. We conducted spatial analyses to identify important breeding habitat on > 500 military installations for 12 species of marsh birds, with the goal of identifying installations that are, and are not, likely to harbor breeding habitat for each species. We also sought to assess the local value of military installations for species of greatest concern by comparing habitat suitability within installations to that in areas directly adjacent to those sites. We built range-wide, spatially-explicit models of species distribution to project suitability of breeding habitat for marsh birds within and adjacent to military installations. Our results demonstrate that installations with the best marsh bird habitat are geographically aggregated (both among and within species), primarily at sites along the eastern seaboard and within the southern U.S. In addition, only a few sites appear to contain high-quality habitat for most species. Five or fewer sites contained most of the high-quality habitat for 9 of 12 species, whereas most of the high-quality habitat for remaining species was found at ≤ 10 sites. This work fills an information gap regarding the distribution of breeding habitat for marsh birds on military lands across the U.S., and should facilitate both strategic conservation of habitat over broad scales and the integration of marsh birds into management efforts at the site level. Our analyses also identify installations that are not likely to harbor breeding habitat for priority species, and thus should help minimize conflicts between needs of the military and marsh-bird conservation.

Managed marshes can be good alternatives to natural marshes as breeding habitats for birds

Loss of natural tidal marshes has caused rapid population declines for many bird species, raising the question about whether managed marshes can be used for bird conservation. Although many studies have indicated that managed marshes can provide a complementary habitat for birds, it is unclear how the breeding habitats provided by managed marshes compare with those provided by natural marshes. We compared habitat conditions (vegetation and food) and breeding performance of a common reed specialist, the Oriental reed warbler (Acrocephalus orientalis), in natural and managed artificial reed marshes (about 2 km × 5 km) at Chongming Dongtan, an estuarine wetland in China. We found that vegetation was denser and warbler food resources were greater in managed than in natural marshes. The density of breeding territories, nest density, clutch size, egg size, and fledgling number per nest were greater in managed than in natural marshes. Breeding failure was reduced in managed marshes because of a reduced risk of nest predation. However, the high nest position on the reeds in the managed marshes increased the risk of nest destruction by strong wind. The better breeding performance in managed than in natural marshes could be attributed to the following factors: the high and stable water level in the managed marshes increased reed growth and arthropod reproduction and decreased access by terrestrial predators; dense vegetation helped conceal nests from predators; and human activities in the managed marshes deterred nest predators. The results suggest that managed marshes can provide quality breeding habitat for the Oriental reed warbler and probably for other marsh birds and can therefore help compensate for the loss of natural marshes. The preference of the Oriental reed warbler for managed marshes largely depends on the suitable habitat conditions. The current study highlights the importance of maintaining a relatively high and stable water level.

Application of Standardized North American Marsh Bird Monitoring Protocols to Survey Inconspicuous Marsh Birds in Korea.

Application of Standardized North American Marsh Bird Monitoring Protocols to Survey Inconspicuous Marsh Birds in Korea.

Habitat Associations of Migratory Waterbirds Using Restored Shallow Lakes in Iowa

Wetlands in the Prairie Pothole Region (PPR) have experienced declines in areal cover, and many remaining wetlands are degraded. Recently, restoration of wetlands has been a key management strategy for waterbirds. In Iowa, the Department of Natural Resources and Ducks Unlimited, Inc. have restored 38 shallow lakes, which are large, mostly permanent wetlands. To assess the impact of habitat variables on migrant waterbird use (waterfowl, shorebirds, and secretive marsh birds), surveys were conducted at 19 shallow lakes restored 1 to 12 years prior to this study and at 11 soon-to-be-restored shallow lakes in Iowa during the spring of 2016-2018. A total of 713,338 waterbirds were identified in 82 species, and more waterbirds and species were detected at restored shallow lakes (582,148 waterbirds and 78 species) than at non-restored shallow lakes (130,895 waterbirds and 70 species). Greatest numbers of diving ducks and waterbird species occurred around 40-50% emergent cover. Water level negatively influenced dabbling ducks and shorebirds and positively influenced diving ducks and total waterbird abundance. Years-since-restoration positively influenced goose/swan abundance and secretive marsh bird abundance, and total wetland area had a positive effect on all groups. These findings emphasize how management strategies for restored shallow lakes should mimic the natural wet-dry cycle of prairie wetlands to provide benefits for all waterbirds.

Vocal Repertoire of the King Rail (Rallus elegans)

Auditory callback is the standard method for monitoring rails and other secretive marsh birds that live in concealing habitats. Due to recent population declines, monitoring the King Rail (Rallus elegans) has become a conservation priority. Analysis of field recordings (n = 542 calls or notes) and behavioral observations were combined to provide an account of the structure and function of the King Rail's vocal repertoire, which included 10 different vocalizations. King Rails produced an array of pulsed sounds by altering frequency, note length, pulse rate, and amplitude of each call. The most commonly heard call, the grunt (61 calls recorded; 37 individuals), had multiple functions including mate communication, duetting, and interaction with neighbors in a ‘roll call’ context. The kek (208 calls; 46 individuals) was the primary mate advertisement call. Most of King Rail's calls, including alarms (165 notes; 7 individuals), screeches (47 calls; 7 individuals), churrs (43 calls; 10 individuals), and the poorly documented boom (5 calls; 5 individuals), were used and sometimes combined in defense and distress situations. Although previously described as a signal of receptivity by females, the kek-burr may also be used in the context of defense. This synthesis is intended to assist researchers and managers in interpreting behavioral observations and improving effectiveness of audio lures for detecting or trapping King Rails.

A Study of Avian Population Recovery after Habitat Restoration Using Remote Sensing and Community Science Bird Observation Data

During the last two centuries, the contiguous United States has lost over half of its wetland habitats. Preserving the remaining wetland habitats and reversing this trend is of critical importance. Fernhill Wetlands in Forest Grove, Oregon is a natural wastewater treatment site that was transformed from unused wastewater ponds to a complex natural wetland habitat in 2014-15. To assess restoration effect on biodiversity changes, previous studies involved manual observations of changes to bird populations. In this study, LANDSAT-8 and SENTINEL-2 satellite imagery and PRISM climate data were used to calculate vegetation, water and climate indices for Fernhill Wetlands for pre- and post-restoration periods, ranging from 2013 to 2018. Then, for the first time quantitative correlations were established between these indices and community science bird observation data from the Cornell University eBird database. The study showed previously unobserved effects of the habitat restoration, positive and negative, on several species. Shorebirds, marsh birds and others that lived at the water’s edge showed much subtler and sometimes unexpected reactions to the habitat change. Further, supervised machine learning classification was used to obtain clarity on land, vegetation and water changes in the region of interest. This study could be of interest to wetland managers to help guide further habitat modifications.

Adaptive management assists reintroduction as higher tides threaten an endangered salt marsh plant

In theory, extirpated plant species can be reintroduced and managed to restore sustainable populations. However, few reintroduced plants are known to persist for more than a few years. Our adaptive‐management case study illustrates how we restored the endangered hemiparasitic annual plant, Chloropyron maritimum subsp. maritimum (salt marsh bird's beak), to Sweetwater Marsh, San Diego Bay National Wildlife Refuge, California, United States, and used monitoring and experimentation to identify the factors limiting the reintroduced population. After extirpation in 1988, reintroduction starting that year led to a resilient, genetically diverse population in 2016 (a “boom” of approximately 14,000) that rebounded from a “bust” (62 in 2014). Multiple regressions attributed 82% of the variation in population counts to tidal amplitude, rainfall, and temperature. Populations of salt marsh bird's beak crashed when the diurnal tide range peaked during the 18.6‐year lunar nodal cycle (a rarely considered factor that periodically added approximately 12 cm to tidal ranges). We explain booms as follows: During smaller tidal amplitudes, above‐average rainfall could desalinize upper intertidal soils and stimulate salt marsh bird's beak germination. Then, moderate temperature in May favors growth to reproduction in June. In addition, salt marsh bird's beak needs a short and open canopy of native perennial plants, with roots to parasitize (not non‐native annual grass pseudohosts) and nearby upland soil for a preferred pollinator, ground‐burrowing bees. Although our reintroduced salt marsh bird's beak population is an exceptional case of persistence, this rare species‐specific environmental and biological requirement makes it vulnerable to rising sea levels and global warming.

Passerine and secretive marsh bird responses to cattail management in temperate wetlands

Hybrid cattails (Typha x glauca) are an invasive, emergent aquatic plant that often form monodominant stands, which can alter wetland vegetation structure and negatively affect wildlife populations. Wetland managers often apply prescribed burning, grazing, and herbicide treatments to reduce cattail density but how these management actions influence wetland wildlife is largely unknown. Our objectives were to investigate the effect of hybrid cattail control methods on secretive marsh bird and wetland passerine abundance in central Minnesota, USA. Specifically, we assessed how environmental variables and cattail treatments (e.g., burning, grazing, and herbicide) influenced bird densities and community composition. We used the North American Marsh Bird Monitoring Protocol to assess wetland bird communities across sixteen wetlands comprised of eight treatments with a full-factorial design. Species-specific density estimates and community-wide ordination offered little evidence for a substantial effect of treatments on marsh birds and passerines. However, gradients in vegetation height and mean biomass did have a significant relationship with both passerine and marsh bird community composition, which suggests changes in the bird community following cattail management might require time to develop. To support diverse wetland bird communities, treatments must create contrast among wetland habitats with high and low vegetative biomass. Because secretive marsh birds are under-surveyed, our baseline population estimates are valuable for future local and regional management and for gaining preliminary understanding of the effect of invasive species management on wetland birds in the Upper Midwest.

Marsh bird occupancy along the shoreline‐to‐forest gradient as marshes migrate from rising sea level

AbstractOne mechanism by which coastal marshes may persist as sea‐level rises is to expand landward into existing forest, a process known as marsh migration. Though recent studies highlight the importance of marsh migration to the conservation of birds associated with coastal marshes, marsh bird responses to this transition from forest to marsh are poorly understood. To address this need, we conducted surveys of five focal marsh bird taxa at 92 points distributed across the gradient from the shoreline to the marsh–forest interface in one of the most vulnerable regions to sea‐level rise in North America where marshes have been migrating landward for at least several decades. Given this landward movement of the forest–marsh interface, we modeled focal taxa occurrence as a function of distance‐to‐forest, thereby assuming that marshes closer to the forest were newer than those closer to the shoreline. In addition, we investigated the effects of vegetation conditions and fire frequency. Occupancy probability of marsh birds decreased closer to the forest–marsh interface where woody vegetation was taller and herbaceous cover was dominated by Cladium jamaicense, suggesting migrated marsh may provide limited habitat for these bird species, at least in the short term. Though parameter estimate uncertainty for black rail (Laterallus jamaicensis) was high due to a limited number of detections, occupancy of this species may increase with the conditions associated with migrated marsh, specifically greater C. jamaicense dominance and decreasing distance‐to‐forest. Clapper/king rail (Rallus crepitans/elegans) occupancy was greater at sites that had burned more frequently over the past decade, and occupancy of all focal taxa was greater in areas with vegetation conditions consistent with the effects of fire in coastal marshes, including reduced herbaceous vegetation density and shorter woody vegetation. As such, prescribed fire may serve as an effective method of facilitating marsh migration and increasing the quality and quantity of habitat for coastal marsh birds as sea‐level rises.

Ecohydrological Changes and Resilience of a Shallow Lake Ecosystem under Intense Human Pressure and Recent Climate Change

In this work we present the complicated situation of a faunistically and floristically valuable ecosystem of the Rakutowskie Lake wetlands complex, which is part of the Special Protection Area for Birds of “Błota Rakutowskie” (PLB40001) and “Błota Kłócieńskie” Habitats Directive Sites (PLH040031) included in the Natura 2000 network. Numerous ornithological observations have drawn our attention to the problem of rapidly progressing overgrowth of the lake and significant fluctuations in its water surface area. These fluctuations, especially in the spring period, significantly limit safe reproduction possibilities of very rare species of water–marsh birds. A multidirectional and comprehensive spectrum of research works allowed us to determine the genesis of the ecosystem and show that the shallow lake is undergoing the final stage in its evolution. The economic aspect of human activity (changes in land use and land development works) has contributed to serious degradation of the ecosystem. Climate changes observed in recent years (increased air temperature and, consequently, higher evaporation) additionally deepen and accelerate this process. The research made it possible to determine how the ecosystem functions today, but it is also an attempt to determine our predictions about its future.

Impacts of Shallow Lake Restoration on Vegetation and Breeding Birds in Iowa

The Shallow Lakes Restoration Project aims to restore eutrophic shallow lakes throughout the Iowa Prairie Pothole Region (PPR). We compared the vegetation taxa richness and frequency of taxa in three vegetation groups surveyed in 2016 and 2017 across non-restored sites, younger restorations, and older restorations. We also assessed the impact of these groups on numbers of breeding marsh birds. Restored wetlands had between 2.7 (95% CI 2.3, 3.2) and 4.7 (95% CI 3.9, 5.5) more species than non-restored sites among the three vegetation groups. Typha sp. was the most abundant emergent species. Lemna minor and Ceratophyllum demersum were the most abundant floating-leaved and submersed species, respectively. The frequency of submersed aquatic vegetation increased with years since restoration, while floating-leaved vegetation and Typha sp. peaked at 7 years post-restoration. The frequency of Typha sp. positively influenced Marsh Wrens and Yellow-headed Blackbirds. Water depth negatively affected Marsh Wrens, but water depth positively influenced Yellow-headed Blackbirds. Floating-leaved vegetation positively affected Virginia Rails, while water depth had a negative effect on this species. Our results indicate that after about 7 years further management of the vegetation and water levels may need to occur and should include maintaining appropriate conditions for breeding marsh birds.

A NEOLOGIZING TAKE ON HIPPONAX, FR. 92.3 WEST

‘When I use a word’, Humpty Dumpty said, in a rather scornful tone, ‘it means just what I choose it to mean—neither more nor less.’In his recent note on Hipponax in this journal, Joseph Cotter first offers ‘a revised version of LSJ's definition’ of ὄρχις. At LSJ (incl. Revised Supplement, 1996), s.v. ὄρχις I, ‘… testicle Hippon. 92.3 W. …’, he would delete the Hipponactean citation and rewrite the second definition, under ΙΙ (‘plant so called from the form of its root …’), to read: ‘from similarity of shape, 1 glans penis, Hippon. 92 (95 Degani), 2. <plant> from the form of its root …’. Cotter derives his new definition from his reading of that Hipponactean line (= fr. 95.3 Degani), καί μοι τὸν ὄρχιν τῆς φαλ[ … , which he supplements with the name of a marsh bird, φαλ[ηρίδος, also redefined. This supplementary ‘coot’ is said to mean ‘cock’, so that the narrator of the fragment's description of (probable) treatment for sexual impotence tells how a Lydian woman ‘thrashed with fig-branch (4, κ]ράδηι συνηλοίησεν) the glans of my cock’. We are presented, then, with two previously unattested meanings of two nouns, ὄρχις and φαληρίς, and an accommodating correction of LSJ. What—I have asked Cotter—might Henry Liddell have thought of these innovations, familiar as he undoubtedly was with Humpty Dumpty's semantics!

Use of autonomous recording units increased detection of a secretive marsh bird

Use of autonomous recording units increased detection of a secretive marsh bird

High Grazing Pressure of Geese Threatens Conservation and Restoration of Reed Belts.

Reed (Phragmites australis (Cav.) Trin. ex Steud.) beds are important habitat for marsh birds, but are declining throughout Europe. Increasing numbers of the native marsh bird, the Greylag goose (Anser anser L.), are hypothesized to cause reed bed decline and inhibit restoration of reed beds, but data are largely lacking. In this study, we experimentally tested the effect of grazing by Greylag geese on the growth and expansion of reed growing in belts along lake shorelines. After 5 years of protecting reed from grazing with exclosures, reed stems were over 4-fold denser and taller than in the grazed plots. Grazing pressure was intense with 50–100% of the stems being grazed among years in the control plots open to grazing. After 5 years of protection we opened half of the exclosures and the geese immediately grazed almost 100% of the reed stems. Whereas this did not affect the reed stem density, the stem height was strongly reduced and similar to permanently grazed reed. The next year geese were actively chased away by management from mid-March to mid-June, which changed the maximum amount of geese from over 2300 to less than 50. As a result, reed stem density and height increased and the reed belt had recovered over the full 6 m length of the experimental plots. Lastly, we introduced reed plants in an adjacent lake where no reed was growing and geese did visit this area. After two years, the density of the planted reed was six to nine-fold higher and significantly taller in exclosures compared to control plots where geese had access to the reed plants. We conclude that there is a conservation dilemma regarding how to preserve and restore reed belts in the presence of high densities of Greylag geese as conservation of both reed belts and high goose numbers seems infeasible. We suggest that there are three possible solutions for this dilemma: (1) effects of the geese can be mediated by goose population management, (2) the robustness of the reed marshes can be increased, and (3) at the landscape level, spatial planning can be used to configure landscapes with large reed bed reserves surrounded by unmown, unfertilized meadows.

Evaluating a focal-species approach for tidal marsh bird conservation in the northeastern United States

ABSTRACT Insufficient time and funding remain obstacles to collecting data across broad spatial scales on the fine-scale distribution of multiple species, their life histories, and interactions with other species and the environment. This often necessitates the use of focal species to inform conservation and management decisions. We used the systematic conservation-planning software Marxan to assess quantitatively whether a focal species can aid in conservation and management of tidal marsh birds. Using a metric of relative cost in the region and current protected areas, we identified priority areas for conservation of 5 specialist taxa—Clapper Rail (Rallus crepitans), Eastern Willet (Tringa semipalmata semipalmata), Acadian Nelson's Sparrow (Ammospiza nelsoni subvirgatus), Saltmarsh Sparrow (A. caudacuta), and Seaside Sparrow (A. maritima)—that nest primarily in tidal marshes in the northeastern United States. We compared the spatial prioritization of sites and cost-effectiveness of alternative protectio...

Spatial and Temporal Changes in Emergent Marsh and Associated Marsh Birds of the Lower Mobile-Tensaw River Delta in Alabama, USA

Sea-level rise, suppression of natural disturbances, and human development of coastal lands have influenced the capacity of tidal marshes to maintain quality habitat for wildlife, including coastal marsh birds. This study targeted the oligohaline marshes of the lower Mobile-Tensaw River Delta, Alabama, USA with the objective of assessing landcover and marsh bird distributional changes relative to two sampling periods, 2004 and 2015. We employed analysis of aerial imagery and standardized marsh bird surveys to derive information on the densities of common gallinule (Gallinula galeata), king rail (Rallus elegans), and least bittern (Ixobrychus exilis) during each sampling period. A gradient of land change was apparent where the northernmost and the southeastern portions of the study area lost land from 2006 to 2013 while the extent of emergent marsh wetland increased in the south and decreased in the north. Average densities of all three birds declined between survey periods (common gallinule 15%, king rail 50%, least bittern 38%). Changes in the distributions of these marsh birds reflected change in landform and emergent marsh habitat. This study reveals that tidal wetlands and associated communities do not change through linear processes. Rather, coastal wetlands may show distinct patterns surrounding areas of accretion, and loss.