Secretive marsh birds, including rails and bitterns, have experienced widespread population declines due to the loss of wetland habitat on which they depend. Because of their cryptic behavior, secretive marsh birds are challenging to study and information on their habitat requirements is limited, especially across the full annual cycle. Quantifying habitat associations throughout the annual cycle and at broad geographic scales can advance a more comprehensive approach for secretive marsh bird conservation. The goal of this study was to quantitatively synthesize results from empirical studies that examined species-habitat relationships of secretive marsh birds in the North American Mississippi Flyway to identify general patterns and information gaps that can guide future management and conservation efforts. We performed a meta-analysis and incorporated results from 40 studies that quantitatively assessed habitat associations of American Bittern (Botaurus lentiginosus), Least Bittern (Ixobrychus exilis), King Rail (Rallus elegans), Sora (Porzana carolina), Virginia Rail (Rallus limicola), and Yellow Rail (Coturnicops noveboracensis). Most studies examined breeding season habitat, whereas only 13% reported on habitat use during migration and none during winter. At landscape scales, breeding marsh birds were positively associated with amount of wetlands, especially in the Great Lakes region, and negatively associated with amount of urban land cover, particularly for American Bittern. At the local scale, breeding marsh birds were positively associated with cattail coverage (Typha spp) and other robust emergent vegetation. Overall, marsh birds were negatively associated with woody wetland vegetation, although effects were weaker in the Prairie region and varied among species. During autumn migration, moistsoil vegetation coverage was important for rails in the lower Midwest. The habitat use patterns we identified across studies provide a general characterization of marsh bird breeding habitat to aid in landscape-level multi-species conservation efforts. Our study also highlights the immediate research needs for full annual cycle conservation of secretive marsh bird habitat in North America: specifically, information during winter and migration.
Despite 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.
Bachman's Sparrow (Peucaea aestivalis) is a species of conservation concern throughout its range and an effective indicator of healthy pine savanna ecosystems in the southeastern United States. Their secretive nesting behavior means that many aspects of their nesting ecology, including specific knowledge of the nest predator community and nest defense behaviors are insufficiently described. This information is an important first step in determining the link between management practices and reproductive success. We monitored 86 Bachman's Sparrow nests, 65 with constant video surveillance, to describe the nest predator community, cause-specific nest mortality rate, and nest defense behavior. We identified 12 predator species from 37 predation events. Snakes were the dominant predator type, responsible for 51% of identified predation events, followed by mesomammals (19%), small mammals (16%), and others (14%). Nest defense behavior included ptiloerection and chasing but was rare (16% of predation events) and effective 67% of the time. Daily nest survival was 0.936 (CI: 0.894-0.967) and neither season, year, nor site explained a significant amount of variation in estimates of cause-specific daily nest mortality. Raccoons were not detected at Bachman's Sparrow nests despite being one of the most common nest predators in other avian nest surveillance studies. Future studies should explore the link between prescribed fire, nest predation, and snake abundance or activity in southeastern pine savanna. Documentation vidéo de prédateurs et de comportements de défense aux nids chez le Bruant des pinèdes RÉSUMÉ. Le Bruant des pinèdes (Peucaea aestivalis) est une espèce préoccupante dans l'ensemble de son aire et est un bon indicateur d'écosystèmes de pinèdes sains dans le sud-est des États-Unis. Leur comportement discret au nid explique que de nombreux aspects de leur écologie de nidification soient encore mal décrits. Cette connaissance est une première étape importante si l'on veut établir les liens entre les pratiques de gestion et le succès de reproduction. Nous avons surveillé 86 nids de Bruant des pinèdes, dont 65 sous vidéo continue, afin de décrire la communauté de prédateurs de nids, le taux de mortalité au nid spécifique aux causes et les comportements de défense au nid. Nous avons identifié 12 espèces de prédateurs à partir de 37 cas de prédation. Les serpents étaient les principaux prédateurs, responsables de 51 % des cas de prédation identifiés, suivis des mésomammifères (19 %), des petits mammifères (16 %) et d'autres prédateurs (14 %). Les comportements de défense au nid comprenaient la ptiloérection et la poursuite, mais ils survenaient rarement (16 % des cas de prédation) et étaient efficaces 67 % du temps. La survie quotidienne au nid était de 0,936 (CI: 0,894-0,967), et ni la saison, l'année ou le site n'ont expliqué l'importante variation des estimations de mortalité quotidienne au nid spécifique aux causes. Les ratons laveurs n'ont pas été détectés aux nids de bruants, bien qu'ils se soient avéré un des p...
Disruption of historic fire regimes has led to the expansion of hardwoods into pine savanna ecosystems in the southeastern United States. Management strategies that reduce mature mesophytic oaks in pine savanna that was previously fire suppressed may help restore understory vegetation and positively affect understory birds. Many private lands in the Southeast are managed intentionally for the Northern Bobwhite (Colinus virginianus; hereafter bobwhite), a species with high cultural and economic importance to the region. Mechanical hardwood reduction is used to restore southeastern pine savanna and as a predation management tool to enhance populations of bobwhite although its utility has not been empirically tested. We measured the demographic response of bobwhite to a large-scale hardwood reduction using a before-after-controlimpact (BACI) study replicated at two properties in the Red Hills region of northern Florida, United States, that had a relatively low density of mature, mesophytic hardwoods and were already managed for bobwhite with 2-year fire return intervals, supplemental feeding, and meso-mammal control. We monitored reproduction at 561 nests and survival of 1529 adults tracked with radiotelemetry. In treated sites, mean daily nest survival was 0.98 and did not change following hardwood reduction. Reproductive effort declined each year (pre-and post-treatment; 2015-2018) in one treated site and varied relatively little in the other. At both treated sites, weekly adult survival decreased to 0.93-0.94 immediately following the treatment, then increased gradually but did not exceed pretreatment weekly survival (0.98) within 2-3 years following the treatment. Our results suggest hardwood reduction may not benefit bobwhite adult survival or productivity within 2-3 years of application on sites that are already managed intensively with prescribed fire, predator control, and supplemental feeding and that hardwoods in this system may not have direct negative impacts on understory birds. Further study is necessary to determine under what conditions hardwood reduction may be beneficial and whether other metrics such as chick survival or immigration are affected. Our study sites represent typical land management in the Red Hills region, and we
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