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The northern Gulf of Mexico is an important stopover and wintering area for many coastal waterbird species, but this region has been little-studied and a paucity of data has hampered efforts to quantify damage caused by disasters such as hurricanes and oil spills. In response, the Audubon Coastal Bird Survey (ACBS) was established to fill this data gap and provide long-term monitoring of coastal birds in this region. This study uses three years of data (2014-2017) from 22 1.6-km transects to identify areas in Mississippi, USA that are important to coastal waterbirds, to compare relative abundance of 14 focal species to abundances prior to the Deepwater Horizon oil spill, estimated using eBird data, and to compare the information gained using ACBS to that of eBird. Shorebirds (Haematopodidae, Recurvirostridae, Charadriidae, and Scolopacidae) were most abundant at barrier island sites; larids (Laridae) were most abundant on man-made mainland beaches; and waders (Ardeidae) were most abundant at vegetated nearshore islands and natural mainland sites. Relative abundances of Least Tern (Sternula antillarum) and Brown Pelican (Pelecanus occidentalis) increased post-spill, while Piping Plover (Charadrius melodus) and Wilson's Plover (C. wilsonia) decreased. Relative abundances estimated using ACBS vs. eBird were greater for seven focal species, particularly for smaller shorebird species.
In the northern Gulf of Mexico, island restoration and creation have been used to mitigate potential negative effects of anthropogenic and environmental stressors to breeding seabirds. The long-term success of such projects can be enhanced when data are available to elucidate how site-specific and larger-scale factors may contribute to reproductive success. Nest-specific daily survival rate (DSR) of Eastern Brown Pelicans (Pelecanus occidentalis carolinensis) during incubation (i.e., pre-hatch; n = 245) and brood-rearing (i.e., post-hatch; n = 185) were measured at two breeding islands in the northern Gulf of Mexico USA in 2017 and 2018 in relation to macro- and micro- scale habitat and environmental measurements. DSR of nests during incubation ranged from 91-99%, and the DSR during brood-rearing exceeded 99% each year. Regional weather variables occurred in top-performing models more often and with more significance compared to microhabitat variables. Results suggest that reproductive success of Brown Pelicans may respond at least in part to weather factors that occur outside of the scope of habitat structure as it is typically incorporated into the restoration or creation of breeding habitat, indicating that climate conditions are likely an important factor in the success of restoration efforts.
Wintering Black-necked (Grus nigricollis) and Common (G. grus) cranes occur sympatrically in Caohai Wetland, Guizhou, China. Seasonal migration dynamics, daily movement patterns, and diurnal activity budgets of the two crane species were investigated in Caohai Wetland, in order to characterize their wintering activity differences and the mechanism of interspecific coexistence, during October - April 2014 - 2017. Black-necked Cranes wintered in Caohai for 147 ± 8 days, and Common Cranes for 169 ± 8 days. Common Cranes generally arrived in Caohai 11.4 ± 3.28 days earlier and departed 11.00 ± 3.20 days later than Black-necked Cranes. During winter in Caohai Wetland, the behavioral activities of both the Black-necked and Common cranes were strongly influenced by circadian rhythms. However, there were significant differences in daily temporal patterns between them in percent time spent in specific behaviors. Common Cranes left their roosting sites 20 min. earlier than Black-necked Cranes and returned 32 min. later. Common Cranes also spent more time foraging and being vigilant than Black-necked Cranes.
The Yellow Rail (Coturnicops noveboracensis) is a secretive marsh bird of conservation concern in Canada. However, the status of this species in northern boreal regions remains largely unknown given uncertainty about population abundance and distribution. This knowledge gap is mainly due to limitations of traditional survey methods to detect this species. In this study, avian point count data collected from autonomous recording units and augmented by detections from a machine-learning recognizer were used to generate a species distribution model to provide habitat-specific density estimates and population size estimates for Yellow Rail breeding in the Edéhzhíe Dehcho Protected Area, Northwest Territories. This protected area is ∼150 km beyond the currently established northern range limit. A large population estimated at 906 (± 146) pairs was discovered. Yellow Rail were found at high densities in marshes (0.063 ± 0.004 males/ha), but were also observed in fens and bogs, albeit at much lower densities (0.003 ± 0.002 males/ha and < 0.001 ± 0.002 males/ha). Our results suggest both the range and the population size of Yellow Rail are much larger than currently reported. Further studies are required to provide better population size and distribution estimates to conserve this species at risk in Canada.
The Geum River, Republic of Korea, is an important wintering site for waterbirds that migrate along the East-Asian Australasian Flyway. It has recently experienced two major changes in environmental conditions as a result of increased use of bale silage (wrapping and sealing forage crops with plastic bags during harvest) beginning in 2007, and the Four Major Rivers Restoration Project (FMRRP) in 2011 to deepen and widen the major rivers in Republic of Korea. To examine these effects on wintering waterbirds, we monitored changes in wintering waterbird abundance in the downstream and upstream regions of Geum River. Wintering waterbirds in the downstream region were reduced by 67% after use of bale silage compared to before bale silage. The FMRRP changed the habitat structure, deepening and widening the river, followed by a substantial decline in overall wintering waterbirds in both regions (38% in the downstream and 51% in the upstream). Mallard (Anas platyrhynchos) and Spot-billed Duck (A. poecilorhyncha) populations showed the most decrease in numbers. However, Common Mergansers (Mergus merganser), that fish in deep water, increased over the same time. The effects of such changes in habitat conditions are not temporary, elucidating the need for monitoring and conservation programs for wintering waterbirds.
The waterfowl populations that visit segments of the Rapti and Narayani Rivers in Chitwan National Park, Nepal were systematically counted from 2010 to 2019 to calculate yearly indices and population trends. Eighteen species of waterfowl were identified, out of which eight were regular visitors. Ruddy Shelduck (Tadorna ferruginea) was 80% of the total waterfowl population. The Rapti and Narayani Rivers provided winter habitat for 15.5% of the Ruddy Shelduck in the South Asian Flyway. Along with Ruddy Shelduck, these rivers individually and regularly supported more than 1% of the population threshold of Goosander (Mergus merganser) in the South Asian Flyway, designating the rivers in Ramsar Criteria 6 in the RAMSAR convention (Wetlands International 2017). Out of eight regular species, six species had an increasing population trend. The long-term trend of Ruddy Shelduck showed a strong increase in the annual rate of population change by + 10.14%. A strong increase was also shown by Bar-Headed Goose (Anser indicus; + 18.96%), Gadwall (Anas strepera; + 12.06%), Mallard (A. platyrhynchos; + 12.44%), and Common Teal (A. crecca; + 12%). Goosander (+ 4.94%) showed a moderate increase, while Lesser Whistling Duck (Dendrocygna javanica; - 12.85%), and Northern Pintail (A. acuta; - 10.80%) showed steep declines in their long-term trends. This work can provide a baseline for management and conservation of the waterfowl of Chitwan National Park, as there is no continuous data available there.
KEYWORDS: Black Rail, breeding ecology, camera trapping, courtship, fire, Laterallus jamaicensis, life history, Parental care, phenology, molt, rallidae
Knowledge of the ecology of the Eastern Black Rail (Laterallus jamaicensis jamaicensis) has remained nearly as elusive as the rail itself. Camera trapping methods facilitated the first study of breeding phenology and chick development, courtship and brood rearing behaviors, and flightless molt phenology and duration. Broods (n = 33) were observed between August 2015 - September 2019. Chicks were capable of flight at approximately 40 days after hatching. Nesting was initiated as early as 17 April 2019 (x̄ = 5 June ± 30.0 SD) and fledging occurred as late as 30 September 2019 (x̄ = 10 August). Behavioral observations combined with phenology data provided evidence of pairs raising two or more broods during a breeding season. Flightless molt (n = 10 adults in molt), which was initiated as early as 15 August 2019 and completed as late as 11 October 2019, was completed within approximately 21 days of initiation. Conservation and management strategies should take into consideration periods of vulnerability, which coincide with increasingly severe and frequent coastal flooding events and hurricanes. It is necessary to understand factors key to fecundity and survival to effectively develop conservation strategies to ensure the persistence of the subspecies.
Habitat use by the Eastern Black Rail (Laterallus jamaicensis jamaicensis) in coastal Texas, USA is poorly understood. To provide data for effective management of the subspecies in Texas, home range size was estimated and habitat use was examined. From February-May of 2017 and 2018, regular locations of 13 radio-transmitted Eastern Black Rails were obtained at San Bernard National Wildlife Refuge, Texas. The mean fixed kernel home range for birds with ≥ 24 relocations was 2.3 ha, with a mean core area of 0.43 ha. Average 95% MCP home range was 0.98 ha with a mean core area of 0.12 ha. During radio tracking, an Eastern Black Rail nest was found on 19 March 2018, the earliest on record for the state. Birds used the Salt and Brackish High Tidal Marsh, Salty Prairie, and Baccharis (Baccharis spp.) Shrubland, and avoided Salt and Brackish Low Tidal Marsh. Home ranges contained a gently sloping elevation gradient suggesting the importance of on-foot access to higher ground. Protection and restoration of Salty Prairie, and Salt and Brackish High Tidal Marsh is recommended for maintaining Eastern Black Rail populations in coastal Texas.
The Eastern Black Rail (Laterallus jamaicensis jamaicensis) is a conservation priority species, yet distributional and habitat data continue to be lacking. In Louisiana, USA, the species is known from 13 documented records and scattered anecdotal reports. From May 2017 to April 2019, we conducted Louisiana's first systematic survey using point count and drag-line techniques. During breeding and non-breeding point counts, we detected one or more Black Rails during 3.1% (n = 1,239) of surveys across 13.8% (n = 152) of point locations at 33.3% (n = 33) of sites. Detection probability was highest from March to May (0.245 ± 0.055 SE) and occupancy was best explained by increasing Gulf cordgrass (Spartina spartinae) cover. During non-breeding season drag-line surveys, we tallied 36 detections at 43.8% (n = 16) of sites. We deployed VHF radios on 13 Black Rails between December 2018 and March 2019 and estimated a home range of 0.71 (± 0.13 SE) ha. These surveys provided the first evidence of a year-round Black Rail population in Louisiana. Additional study is urgently needed to understand habitat management needs, including prescribed fire, mechanical shrub removal, and cattle (Bos taurus) grazing intensities. Meanwhile, aggressive conservation actions are needed to preserve remaining habitat.
Documenting the spatial distribution of high-quality habitat patches, the distributions of threats and protected areas, and the vulnerability of habitat patches to changes in environmental conditions is vital for conservation of rare species. Range-wide species distribution models were developed for Black Rails (Laterallus jamaicensis) to predict the distribution of high-quality habitat patches for breeding Eastern Black Rails (L. j. jamaicensis). Overlay analyses were conducted to quantify the distribution of habitat relative to human development and existing protected areas, as well as the vulnerability of the best habitat to future sea level rise. The amount of high-quality habitat varied among states (0.4-7.6% of area) and was relatively rare throughout the subspecies' range (3.3% of area). Human development was common but the amount varied spatially among states (2.2-15.3% of area). Higher-quality breeding habitat was more common on federal lands (9.4% of area) and protected areas (6.4% of area), yet 33-42% of the highest-quality habitat patches were vulnerable to sea level rise of 0.61-1.83 m. Our results imply that even though many of the highest-quality habitat patches may be less likely sites for development they are often vulnerable to rising seas, and thus maintenance of existing high-quality habitat patches may be difficult without management that takes into account the likelihood of future inundation.
Eastern Black Rails (Laterallus jamaicensis jamaicensis) were surveyed during 1990, 2007, 2014 within the Chesapeake Bay region in Maryland and Virginia, USA. A network of point count locations (n = 182) was established and surveyed within tidal salt marshes. Occupancy declined during the study period from 0.84 ± 0.13 (ψ ± SE) in 1990 to 0.06 ± 0.02 in 2014. The annualized rate of decline was estimated to be 6.5%. Extinction and colonization rates between 1990 and 2014 were 0.81 ± 0.09 and 0.04 ± 0.02 respectively. Abundance declined from 1.98±0.05 Black Rails/point in 1990 to 0.26 ± 0.02 in 2014 with a 3.2% annualized rate of decline. Recruitment was 1.32 ± 1.35 between 1990 and 2007 and 0.003 ± 0.05 between 2007 and 2014. Species detection was negatively influenced by advancing season and waxing moon phase while individual detection was most strongly influenced by survey year and advancing season. Anecdotal observations of range-wide strongholds within the Chesapeake Bay suggest that sites have experienced significant declines with birds being extirpated by 2016. Declines throughout the core breeding area and within individual strongholds in the Chesapeake Bay are consistent with Black Rail declines in tidal habitats throughout the broader Northeast region.
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