Ixobrychus Exilis Research Articles

THE ASSESSMENT OF THE TROPHIC RELATIONSHIPS OF THE MIGRATORY-NESTING BIRDS POPULATIONS BELONGING TO THE FAMILY OF ARDEIDAE IN THE GIZILAGHAJ BAY

In 2013-2023, in the Gizilaghaj Bay located on the South-Western coast of the Caspian Sea, the trophic relationships of the migratory and nesting bird populations belonging to the Ardeidae family (Botarus stellaris, Ixobrychus minutus, Nycticorax nycticorax, Ardeola ralloides, Bubulcus ibis, Egretta garzetta, Ardea alba, Ardea cinerea, Ardea purpurea) were evaluated with 100 points. It was evaluated 40-60 (sufficient) in 36 species, the main food objects of which are plants, in 9 species 60-80 (good). It was evaluated 40-60 (sufficient) in 12 species of birds, the main food objects of which are invertebrates, 60-80 (good) in the populations of 114 species and 80-100 (very good) in 10 bird species. It was evaluated 0-20 (very bad) in 14 species, the main food objects of which are vertebrates, 20-40 (bad) in 18 species, 40-60 (sufficient) in 56 species and 60-80 (good) in 10 species.

Investigations of the tick burden on passeriform, water-associated and predatory birds reveal new tick-host associations and habitat-related factors of tick infestation.

Previous studies on the tick infestation of birds in the Carpathian Basin focused on songbirds (Passeriformes). Thus, the primary aim of the present work was to extend the scope of previous studies, i.e. to include aquatic (water-associated) bird species in a similar context, especially considering that these birds are usually long-distance migrants. Between March 2021 and August 2023, 11,919 birds representing 126 species were checked for the presence of ticks. From 352 birds belonging to 40 species, 905 ixodid ticks were collected. Tick species were identified morphologically and/or molecularly. Ticks from avian hosts belonged to seven species: Ixodes ricinus (n = 448), I. frontalis (n = 31), I. festai (n = 2), I. arboricola (n = 36), I. lividus (n = 4), Haemaphysalis concinna (n = 382) and Dermacentor reticulatus (n = 2). Nymphs of I. ricinus occurred with a single activity peak around March-May, whereas its larvae typically infested birds in May, June or July. By contrast, H. concinna usually had its activity maximum during the summer (nymphs in June-July, larvae later in July-August). Interestingly, two ornithophilic species, I. frontalis and I. arboricola, were most active around winter months (between October and April). A significantly lower ratio of aquatic birds was found tick-infested than songbirds. Several new tick-host associations were revealed, including I. ricinus from Greylag Goose (Anser anser) and D. reticulatus from Great Egret (Ardea alba) and Sedge Warbler (Acrocephalus schoenobaenus). Ticks were collected for the first time in Europe from two species of predatory birds as well as from Little Bittern (Ixobrychus minutus). Bird species typically inhabiting reedbeds were most frequently infested with H. concinna, and most ticks localized at their throat, as opposed to forest-dwelling avian hosts, on which I. ricinus predominated and ticks were more evenly distributed. In the evaluated region, aquatic birds appear to be less important in tick dispersal than songbirds. However, newly revealed tick-host associations in this category attest to their hitherto neglected contribution. The results suggest that the habitat type will have significant impact not only on the species composition but also on the feeding location of ticks on birds.

Habitat preferences of a secretive marsh bird using a man-made habitat: the case of Little Bittern (Ixobrychus minutus minutus)

Many marsh birds, like bitterns or rails, are endangered species inhabiting only natural habitats and dependent exclusively on different types of emergent vegetation. In a changing environment, some of these habitat specialists are becoming more flexible, shifting their preferences by colonizing man-made habitats. We studied habitat selection by Little Bitterns (Ixobrychus minutus minutus) breeding in a fishpond landscape in south-eastern Poland. Applying a large-scale research approach, we examined several habitat features in order to predict the presence of the Little Bittern from a direct comparison of areas with and without breeding birds. Partial least squares (PLS) regression identified two components of several variables that explained 53% of the variation in the presence of the Little Bittern in a fishpond habitat. The occurrence of the Little Bittern was limited to high-quality patches of emergent vegetation, the height, width and area of which were all significantly greater in the area with breeding birds than in unoccupied patches. Patches with a highly variable edge line in the form of fringes or indentations were less favoured. An optimal water level throughout the breeding season was crucial for nest-site selection and ensured access to food. The heterogeneity of the pond dykes and pond canals positively predicted the presence of the Little Bittern by creating potential nesting or foraging sites. Interestingly, the proportion of bulrushes (Typha spp.) in the emergent vegetation patches had a negative effect on the presence of the Little Bittern. The main threat to this habitat‐sensitive species was the cutting of perennial emergent vegetation, in particular the Common Reed (Phragmites australis).

Water depth influences survival and predator-specific patterns of nest loss in three secretive marsh bird species.

Wetlands have become increasingly rare in the United States, negatively influencing wetland-dependent birds, and many remaining wetlands are intensively managed through seasonal dewatering mimicking historic flood pulses during spring and summer. However, water around nests may provide protection from terrestrial predators, and lowering water levels during the breeding season of wetland birds may increase predation risk and exacerbate marsh bird population declines. Understanding interactions between water depth, nesting marsh birds, and nest predators is critical to aid managers in developing a multi-species management approach in emergent wetlands. During the 2020 and 2021 breeding seasons, we examined nest survival of 148 marsh bird nests (American Coot, Fulica americana, n = 1; Common Gallinule, Gallinula galeata, n = 64; and Least Bittern; Ixobrychus exilis, n = 83) and installed cameras at 78 nests to identify predators at a large, restored floodplain wetland in Illinois where the primary management technique is seasonal water removal to stimulate germination of moist soil plants. We found nest predation of, and abandonment by, Least Bittern and Common Gallinule were related to shallower water, and early season, high volume dewatering. Least Bitterns nested more commonly along wetland edges and nests farther from the shore were more likely to survive. Similarly, we found mammalian depredation of nests and nest abandonment decreased when deeper water was present around nests. Alternatively, snake predation was observed earlier in the year prior to water removal from inundated emergent vegetation. Our results demonstrate water depth may be an important deterrent of nest predators, especially mammals, during the breeding season. Further, we recommend managers delay dewatering until after the nesting season at sites where management for conservation-priority marsh birds is a focus.

Feeding ecology and reproductive success of the Little Bittern Ixobrychus minutus in differently managed pond habitats

Knowledge of the relationships between food habits and habitat is crucial for the assessment of habitat quality for birds. The present study investigated the diet and reproductive success of Little Bitterns Ixobrychus minutus nesting on cyprinid fish ponds, an important breeding habitat of this species in central and eastern Europe. Being subject to different management practices, fish ponds provide food resources of uneven availability for this small heron. Prey items regurgitated by nestlings were examined, and breeding success was estimated on monoculture ponds stocked either with small fish (of a size suitable for feeding nestlings) or large fish (unavailable to Little Bitterns and adversely affecting their non-fish prey), on abandoned ponds dominated by small fish but with large fish also present, and on angling ponds dominated by large sport fish but harbouring significant numbers of small fish as well. A total of 1356 prey items from 78 broods were identified. Although Little Bitterns exhibited dietary flexibility in response to the contrasting availability of prey on their nesting ponds, the bulk of the nestlings’ diet consisted of fish. The size of fish brought to the nest increased significantly with brood age, showing that parents adjusted the prey size to the gape constraints of their young. The chick production determined for 73 broods did not differ with respect to pond management, but the dietary composition indicated that to compensate for food shortages, birds nesting on ponds containing mainly large fish made foraging flights to food-richer ponds. The abundance of small-sized fish prey may be a factor limiting the breeding success of small- and medium-sized predatory waterbirds and should be taken into consideration in management strategies of habitats dominated by fish.

Marshbird response to herbicide control of cattail in northwestern Minnesota

AbstractWetlands provide essential habitat for a wide variety of wildlife species. In the once wetland‐rich Prairie Pothole Region and adjacent areas of central North America, many wetlands have been converted to agricultural production. Many remaining wetlands experience ecological change via the invasion and spread of non‐native plant species, such as non‐native narrowleaf (Typha angustifolia) and hybrid cattail (Typha x glauca), which spread aggressively and displace native vegetation, especially in large, impounded wetlands. Management of wetlands in these landscapes often includes broad‐scale herbicide application intended to break up mats of cattail and restore areas to more wildlife‐friendly conditions. Although restoration of wildlife habitat is a common goal of such management, marshbird response to invasive cattail control is poorly understood. To evaluate the effects of cattail management on wetland wildlife, we conducted standardized call‐broadcast surveys for 5 species of marshbirds at 9 study sites that included survey locations associated with areas treated with herbicide and paired areas not treated with herbicide in wetland impoundments in northwestern Minnesota, USA, using a before‐after, control‐impact study design. We surveyed American bitterns (Botaurus lentiginosus), least bitterns (Ixobrychus exilis), pied‐billed grebes (Podilymbus podiceps), soras (Porzana carolina), and Virginia rails (Rallus limicola) during the breeding season prior to herbicide application (late summer and early autumn of 2015) and during the 3 breeding seasons after herbicide application (2016–2018). We modeled species counts using a generalized linear mixed model with year‐by‐treatment interactions as fixed effects and site as a random effect. Before herbicide application, expected mean counts did not differ between treatment and control survey locations. Three years post‐treatment, we detected significant increases in expected mean counts at treatment compared to control survey locations for soras (t193 = −3.373, P = 0.020) and Virginia rails (t193 = −3.167, P = 0.037), and point estimates for all species except least bittern were higher at treatment survey locations. Overall, our results suggest that these marshbird species responded positively to herbicide control of invasive cattail and that breeding marshbirds in these and similar wetland systems may experience positive population response over a period of at least 3 years following treatment.

Successful nest defence of Eurasian reed warblers Acrocephalus scirpaceus against the little bittern Ixobrychus minutus

The cost–benefit approach to nest defence behaviour is based on an assumption that parents are able to distract potential predators away from their nest. However, this assumption has received little support from direct observations as predator-prey encounters near nests are rarely recorded, especially in small passerines. Here, we describe two observations of little bitterns appearing near nests of Eurasian reed warblers containing nestlings and eggs, respectively. In both cases parental birds showed anti-predatory behaviour, which was much more vigorous at the nestling stage than at the egg stage. During both observations, the heron finally flew away and did not attack the nest content, indicating that nest defence behaviour of small passerines may be effective.

Marsh birds as ecological performance indicators for Lake Ontario outflow regulation

Water-level regulation can have significant impacts on coastal wetland ecosystems. In this study we sought to update marsh-bird-based ecological performance indicators (PIs) that support adaptive management of long-term outflow regulation for Lake Ontario. Previous PIs established in the mid-2000 s were based on single species and monitoring them required data not currently being collected at broad scales. We therefore focused on developing and validating community-level PIs using data from an ongoing, long-term, basin-wide monitoring program, the Coastal Wetland Monitoring Program (CWMP). After identifying species with documented responses to variation in water levels in the literature, we considered a suite of potential PIs by first examining correlations with both annual mean water levels and measures of interannual water-level fluctuations. We then used a mixed-modelling framework to determine which highly correlated PIs exhibited statistically significant relationships with water-level variables. Having established significant effects of water levels on the candidate PIs, we performed a power-sensitivity analysis to determine the degree of change in each PI that can be detected based on current CWMP sampling. From these analyses, we propose six potential marsh-bird based PIs: sum total abundance of sensitive marsh-obligate species, richness of sensitive marsh-obligate species, and abundance of each of red-winged blackbird (Agelaius phoeniceus), marsh wren (Cistothorus palustris), common gallinule (Gallinula galeata), and least bittern (Ixobrychus exilis). Of these, the community-based PIs of sum total abundance and richness of sensitive species appear most suitable for assessing the marsh-bird community response to outflow regulation on Lake Ontario.

Great Meadows National Wildlife Refuge, Massachusetts, USA: A Wetland of Distinction

Great Meadows National Wildlife Refuge in eastern Massachusetts has been recognized as a Wetland of Distinction by the Society of Wetland Scientists. It provides essential habitat for migratory birds as well as for resident wildlife including state endangered birds: least bittern (Ixobrychus exilis), pied-billed grebe (Podilymbus podiceps), upland sandpiper (Bartramia longicauda), American bittern (Botaurus lentiginosus), and two state threatened species grasshopper sparrow (Ammodramus savannarum) and king rail (Rallus elegans). Great Meadows also harbors the largest genetically distinct populations of threatened Blanding’s turtle (Emydoidea blandingii) in the Northeast. The refuge also provides outdoor recreation opportunities (hunting, fishing, and nature observation) and a place for environmental education.

Spatial drivers of wetland bird occupancy within an urbanized matrix in the Upper Midwestern United States

AbstractWetland birds are undergoing severe population declines in North America, with habitat degradation and wetland loss considered two of the primary causes. Due to the cryptic nature of many wetland bird species, the ecological conditions (e.g., matrix composition) that influence bird occupancy, and the relevant spatial scales at which to measure bird responses, remain unclear but may affect inference about wetland use and suitability. We conducted wetland bird surveys at 477 points across northeastern Illinois and northwestern Indiana within the highly urbanized landscape surrounding Chicago. Using remotely sensed land cover data, we built occupancy models for 10 wetland bird species (American Coot Fulica americana, Black‐crowned Night‐Heron Nycticorax nycticorax, Blue‐winged Teal Anas discors, Common Gallinule Gallinula galeata, Least Bittern Ixobrychus exilis, Marsh Wren Cistothorus palustris, Pied‐billed Grebe Podilymbus podiceps, Sora Porzana carolina, Swamp Sparrow Melospiza georgiana, and Virginia Rail Rallus limicola) to quantify their responses to wetland cover types (emergent wetland, forested wetland, riverine wetland, and freshwater pond) and urbanization at four spatial scales (200‐, 400‐, 800‐, and 2000‐m radial distances). We also included the distance to Lake Michigan as a covariate in occupancy models to account for ecological differences between coastal and inland wetlands. We found that relationships between land cover types and occupancy differed by species, as did the spatial scale of support. Generally, the presence of emergent wetlands or ponds at immediate (200 m) and local (400 m) spatial scales within the surrounding matrix was positively associated with wetland bird occupancy. Contrary to expectations, we did not find support for a negative relationship between urbanization and occupancy for most focal species, indicating that birds are using available wetland habitats despite surrounding development. While future research should evaluate management strategies at the watershed scale, our findings suggest that wetland conservation planning at immediate and local scales is likely to promote bird habitat use within highly modified landscapes of the Upper Midwestern United States.

Influence of breeding time, nest size, water depth, and egg size on the breeding success of the little bittern Ixobrychus minutus

Understanding the factors that influence avian reproductive output is critical for bird conservation as they reveal key considerations that directly impact a species’ long term survival and should be integrated into management plans. To better this understanding for the little bittern Ixobrychus minutus, we investigated how their breeding success relates to breeding time, nest size, water depth, and egg size in a man-made wetland (Ab-bandan) during the 2008 breeding season in Mazandaran Province, northern Iran. For each nest, the dates of the first egg laying, the first hatching, and the first fledging were recorded as well as clutch sizes. Nest size parameters (height, depth, and diameter), water depth under the nest, and egg characteristics (shape index and weight) were measured. The first egg was laid on March 21 and the last chick left the nest on June 24. From 140 eggs in 25 nests, 127 eggs hatched (91%) and 121 fledglings left their nests (87%). Generalized linear modeling revealed that nest diameter positively affected breeding success ( p = 0.001) meaning larger nests were more likely to produce fledglings. Further studies will be necessary to elucidate the underlying mechanisms.

Marsh bird response to restored shallow lakes: Implications for future management

AbstractThe restoration of shallow lakes has the potential to provide habitat for obligate breeding marsh birds, including secretive marsh birds. However, the degree of marsh bird response to wetland restoration may vary over time as prairie wetlands are subject to variation in water depth and vegetation characteristics (e.g., height, density, distribution) because of management and biotic and abiotic factors. We investigated the effects of shallow lake restoration age and habitat covariates on the abundance of 3 secretive marsh bird species and marsh bird species richness at shallow lakes in northern Iowa from 2009–2010 and again from 2016–2017. We found that the interspersion of water and emergent vegetation, shallow lake area, and water depth influenced the abundance of pied‐billed grebes (Podilymbus podiceps). Restoration age (β = −0.52, 95% CI = −0.87, −0.18) had a quadratic effect on abundance of pied‐billed grebes, peaking at 6 years post‐restoration. Percent cattail (β = 1.95, 95% CI = 0.55, 3.35) and restoration age (β = 0.51, 95% CI = 0.14, 0.87) were important predictors for Virginia rail (Rallus limicola) abundance. Species richness was greater at restored shallow lakes ( = 2.72, 95% CI = 2.23, 3.23) compared to non‐restored shallow lakes ( = 3.91, 95% CI = 3.41, 4.56) and at shallow lakes with a greater percentage of cattail ( = 2.54, 95% CI = 2.13, 3.07 at 0% cattail to = 4.27, 95% CI = 3.47, 5.15 at 100% cattail). Restoration age did not significantly influence least bittern (Ixobrychus exilis) abundance or species richness, but both variables tended to peak between 5 to 8 years after restoration. Our findings illustrate the need to evaluate habitat characteristics of individual shallow lake restorations as they age to inform continued management efforts for breeding marsh birds.

Secretive marsh bird habitat relationships at mid‐continent spring migration stopover sites

AbstractDespite several secretive marsh bird (SMB) species being listed as critically imperiled throughout the mid‐continent of North America, limited information on SMB distribution and habitat use within primary migratory corridors results in uncertainty on contributions of wetlands in mid‐latitude states toward their annual cycle needs. Our objectives were to quantify temporal patterns of SMB wetland occupancy during spring migration at a mid‐latitude state and evaluate the relationships between SMB colonization probability and water‐level management practices, and the resulting habitat conditions during spring migration. We conducted a 2‐year, dynamic occupancy study (2013–2014) that included 6 rounds of repeated call‐back surveys to detect the presence of 5 SMB species (i.e., Virginia rail [Rallus limicola], sora [Porzana carolina], king rail [R. elegans], least bittern [Ixobrychus exilis], and American bittern [Botaurus lentiginosus]) during spring (Apr–Jun) on 107 wetlands across 8 conservation areas and 4 national wildlife refuges throughout Missouri, USA. We detected sora most frequently, followed by least bittern, American bittern, Virginia rail, and king rail. Coefficient estimates indicated colonization probability for all species was positively associated with emergent vegetation cover and negatively associated with amount of open water. Open water was the only variable in the best supported model explaining American bittern site colonization, to which they were negatively associated. Virginia rail colonization had a strong positive association with vegetation height, whereas least bittern and sora site colonization were influenced positively by water depth and agriculture, respectively. Based on the habitat associations within and among SMB species identified in this study, wetland managers can tailor management strategies to optimize spring migration habitat for single‐ or multi‐species objectives.

A Survey of the Ectoparasites Found on Wild Birds in Northwest Turkey

Background: Turkey is home to various resident and migratory wild bird species. The aim of the present study was to investigate the ectoparasites found on 188 injured or rescued resident and migratory wild birds from Bursa and surroundings between 2015 and 2019. Methods: Sampled birds were examined for different ectoparasites and all of the collected parasites were placed into tubes containing 70% ethyl alcohol. After mounting onto slides or fixing onto a plate, each parasite was identified to species using a light or stereo microscope. Result: Results revealed that 88 (46.8%) of the examined wild birds were infested with one or two of 3 different species of ectoparasites. The species identified were 38 lice, three ticks and two flies. The lice were highly prevalent (40.4%) species than the flies (2.1%) and ticks (2.1%). The results also first geographically documented the lice and ked fly species as follows, with additional new host records: Fulicoffula gallinula and Pseudomenapon pilosum in the common moorhens (Gallinula chloropus); Ciconiphilus decimfasciatus in the grey heron (Ardea cinerea); Saemundssonia clayae in the Eurasian woodcock (Scolopax rusticola); Ardeicola ixobrychae in the common little bittern (Ixobrychus minutus) and the ked fly as Ornithophila metallica in the Eurasian magpies (Pica pica) in Turkey. The study results provided valuable data on the ectoparasites living on migratory and resident bird species during their migration throughout northwest Turkey. Further research on the related pathogens that these ectoparasites harbor is in need.

Close to the Madding Crowd: Waterbird Responses to Land Use Conversion in and Around a Mediterranean Urban Wetland

Investigating how Mediterranean wetlands respond to adjacent land use conversion, is an important first step in mitigating the impact of human encroachment and other environmental stressors. We monitored the composition and structure of waterbird assemblages, in a Mediterranean urban marsh, subjected to severe anthropogenic pressures. Remote sensing indicated that in the last two decades Boussedra Pond was subjected to landfill, resulting in a substantial reduction (~ 50 %) of the marsh, while due to a lack of urban planning urban built-up and agriculture areas expanded considerably in its surroundings. This precipitous reduction of the size of this urban pond threatens the diversity of its resident waterbirds which include the globally Endangered (EN) White-headed Duck Oxyura leucocephala, the Near-Threatened (NT) Ferruginous Duck Aythya nyroca, and many other staging and wintering migratory species. The long-term study suggested that breeding waterbirds species responded differentially to the loss and degradation of the marsh, as highlighted by the apparent resilience of the synanthropic Moorhen Gallinula chloropus and the disappearance of several breeding marsh specialists, such as the Little Bittern Ixobrychus minutus and the Western Marsh Harrier Circus aeruginosus. The study also points out the need for both a coordinated cross-sectorial land use planning and an immediate, affordable and sustainable wetland conservation action.

Offspring sex ratio and partially asynchronous hatching in the Little Bittern (Ixobrychus minutus) population in south-western Slovakia

Birds are one of the best-studied animal groups in Europe. Despite this, there are several bird species, including the Little Bittern (Ixobrychus minutus), of which the breeding biology is still little known. Here, I examine the sex of offspring in relation to hatching order, the degree of hatching asynchrony and some other aspects of nesting biology (such as breeding phenology, clutch size, egg and nestling survival) of the Little Bittern in the south-western Slovakian population. Egg-laying occurred from 5 May to 10 July, but the majority of clutches were initiated in May. Mean clutch size was 5.2 ± 0.92 (SD) eggs. Parents initiated full incubation predominantly after laying the third egg (86.4% of cases) of the clutch, which led to only partially asynchronous hatching of eggs. However, no evidence was found for offspring sex ratio adjustment according to hatching order. Nevertheless, survival rates of eggs and nestlings were relatively high (80.9% and 94.3 %, respectively). The possible causes of observed patterns are discussed.

Nestling Diet and Breeding Success of Little Bitterns Ixobrychus minutus at Two Artificial Fishpond Complexes in South-Western Slovakia

Artificial fishponds are assumed to be suitable alternative habitat for many waterbirds including fish-eating predators such as herons. However, fish farming may lead to contrasting consequences for birds breeding in these biotopes and act as an ecological trap. I examined nestling diet and reproductive success of the least studied heron species in Europe, the endangered Little Bittern Ixobrychus minutus, at two fishpond complexes in south-western Slovakia. A total of 95 breeding attempts by this species were recorded during 2015–2019 in the study area, 84% of which produced at least one nestling. Despite relatively high nest success at both sites, the number of fledged nestlings differed significantly between the two fishpond complexes. The observed differences were mainly caused by higher nest predation at one of the fishponds. The diet of nestlings also differed between study sites. While the food taken at fishponds that are used for intensive farming of Common Carp Cyprinus carpio contained significant proportions of insects (41%) and amphibians (14%), at fishponds used mainly for individual sport fishing, parents fed their nestlings exclusively fish. However, the total amount of food delivered to nestlings was similar at both fishpond complexes. This suggests that Little Bitterns are able to adapt to fishponds with various intensities of management. Nevertheless, considering differences in nest predation risk between studied fishponds, other factors such as abundance and structure of littoral vegetation and predator abundance, can influence the breeding success of this species in artificial fishpond habitats. Identifying such factors may be important for the conservation and management of this species.

Effects of barrier island salt marsh restoration on marsh bird occurrence in the northern Gulf of Mexico

In the northern Gulf of Mexico, salt marshes are threatened by sea level rise, erosion, and loss of protective barrier islands. These barrier islands provide critical habitat for wildlife, including globally significant populations of marsh and shorebirds. We investigated salt marsh restoration on two Louisiana barrier islands using presence of eight marsh bird species as an index to evaluate restoration success. Land loss was extensive for both islands prior to restoration, with submerged marsh restored by backfilling sediment into the marsh platform. Restoration methods were similar between the two islands, although Raccoon Island was built to a higher elevation (1.1 m) than Whiskey Island (0.8 m). Avian presence was estimated via passive acoustic monitoring and point counts. To evaluate restoration success, we modeled influence of habitat covariates on index species presence in restored and reference (intact) sites over three breeding seasons and modeled occupancy for six species. On Whiskey Island, index richness was higher in restored sites. Marsh specialists Seaside Sparrows (Ammospiza maritima) and Least Bitterns (Ixobrychus exilis) had higher occupancy in restored areas on Whiskey, while generalist species showed no response to site. These results are likely due to a strong association between habitat and vegetation type, with restored sites dominated by Spartina alterniflora and reference sites by Avicennia germinans. On Raccoon Island, species richness was low across all sites. Our results suggest that restoration efforts were successful in creating salt marsh habitat on Whiskey but not Raccoon as of the time of our study.

Broadcasting Regional Call Dialects Has Little Influence on the Effectiveness of Call-Broadcast Surveys for Marsh Birds

Emergent wetlands have declined in North America and, in response, many wetland-dependent animals have declined in abundance. For example, many species of secretive marsh birds in North America have declined during the last century. However, estimates of population decline and efforts to assess the effects of management actions are hampered because marsh birds are difficult to detect using conventional survey techniques. Call-broadcast surveys can improve detection probability of marsh birds; however, the effectiveness of call-broadcast varies regionally for some marsh birds, which might reflect differential responsiveness to call dialects. Here, we evaluated differential responses by least bitterns (Ixobrychus exilis) and clapper rails (Rallus crepitans) to different call dialects by using 679 paired call-broadcast surveys in Florida and South Carolina. We detected similar numbers of least bitterns and clapper rails responding to the different call dialects, except in Florida, where least bitterns responded more frequently to a more-distant (Louisiana) dialect than a more-local (Florida) dialect. Our results suggest that, at least for clapper rails and least bitterns, it may not be necessary to incorporate regional call dialects into standardized surveys. However, additional research is needed in more regions of North America and with other species.

Species‐Habitat Relationships and Priority Areas for Marsh‐Breeding Birds in Ontario

ABSTRACTPopulations of marsh‐breeding birds have declined throughout the southern Laurentian Great Lakes basin. To advance conservation of these species, we used occupancy modeling, a regional prioritization scheme, and data from Birds Canada's Great Lakes Marsh Monitoring Program (2016–2018) to describe species‐habitat relationships and identify priority habitat areas for 7 obligate marsh‐breeding bird species in southern Ontario, Canada: American bittern (Botaurus lentiginosus), common gallinule (Gallinula galeata), least bittern (Ixobrychus exilis), marsh wren (Cistothorus palustris), pied‐billed grebe (Podilymbus podiceps), sora (Porzana carolina), and Virginia rail (Rallus limicola). Given these species respond to land cover at widely varying spatial scales, we initially identified the most informative scale (buffer = 100 m, 200 m, 400 m, 800 m, 1,600 m, 3,200 m, or 6,400 m) for marsh, urban, agricultural, and forest cover to increase model performance. We also considered climate variables, whether sample sites were along a Great Lakes coastline or inland, and covariates influencing detection. Occupancy was best explained by land cover at a wide range of spatial scales depending on the species. All species except Virginia rail responded positively to marsh cover; American bittern and Virginia rail responded negatively to urban cover; least bittern, pied‐billed grebe, and Virginia rail responded negatively and sora responded positively to agricultural cover; and American bittern, common gallinule, marsh wren, and pied‐billed grebe responded negatively and Virginia rail responded positively to forest cover. Only American bittern responded negatively to mean May–June temperature; only pied‐billed grebe responded positively to start of growing season; and only Virginia rail had higher occupancy at inland marshes compared to coastal. We combined predictions from the best model for each of 5 species with reasonably good model fit (we excluded sora and Virginia rail) to identify priority habitat areas for marsh‐breeding birds. Expansion of wetland conservation work from existing priority areas based on waterfowl to also include these new additional priority areas based on marsh‐breeding birds will be an important step towards conservation of all birds, and will help slow or maybe even reverse declining population trends. Some restoration activities outside but adjacent to priority areas will also be important for rebuilding marshes for these species across this intensively farmed and developed region. © 2020 The Wildlife Society.