Observations of Molt in an Endangered Rallid, the Hawaiian Moorhen

DesRochers, David W.; Butler, Luke K.; Silbernagle, Michael D.; Reed, J. Michael

doi:10.1676/08-064.1

Cited by 7 publications

(7 citation statements)

References 30 publications

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“…Starting in 2014, annual surveys from May to August were conducted island-wide, and we expanded banding efforts to include wetlands across the entire island of O'ahu ( Figure 2). May-August survey periods were chosen due to the availability of personnel, but they are not considered a source of bias given the absence of a strong annual cycle in Hawaiian gallinule life history (DesRochers et al 2009;USFWS 2011). Birds were identified by a unique combination of colored plastic (Darvic) leg bands and an aluminum U.S. Geological Survey leg band.…”

Section: Survival and Movementmentioning

confidence: 99%

“…Years were determined based on calendar date (years start January 1 and end December 31), which was chosen for computational convenience. As with banding field seasons, the year was not considered to be a source of bias because of the weak seasonal breeding phenology of Hawaiian gallinules (DesRochers et al 2009;USFWS 2011) and because the majority (.70%) of marking and sighting events occurred during May-August. Resighting data were converted to yearly encounter histories and MARK input files by using an R script written by the authors.…”

Section: Survival and Movementmentioning

confidence: 99%

“…Despite being federally protected, with substantial resources allocated to studying their ecology, status, and management (DesRochers et al 2009(DesRochers et al , 2010Gutscher-Chutz 2011;Reed et al 2011Reed et al , 2012USFWS 2011;Underwood et al 2013), published data on vital rates for this subspecies are limited or absent. A single published paper (Byrd and Zeillemaker 1981) and three unpublished theses (Nagata 1983;Chang 1990;Gee 2007) are the only reports of Hawaiian gallinule reproduction, and to date there have been no studies of survival rates.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Vital Rates for the Hawaiian Gallinule, a Cryptic, Endangered Waterbird

Rees

Chang

Cosgrove

et al. 2018

Journal of Fish and Wildlife Management

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Vital rates describe the demographic traits of organisms and are an essential resource for wildlife managers to assess local resource conditions and to set objectives for and evaluate management actions. Endangered waterbirds on the Hawaiian Islands have been managed intensively at state and federal refuges since the 1970s, but with little quantitative research on their life history. Information on the vital rates of these taxa is needed to assess the efficacy of different management strategies and to target parts of the life cycle that may be limiting their recovery. Here, we present the most comprehensive data to date on the vital rates (reproduction and survival) of the Hawaiian gallinule Gallinula galeata sandvicensis, a behaviorally cryptic, endangered subspecies of wetland bird endemic to the Hawaiian Islands that is now found only on Kaua‘i and O‘ahu. We review unpublished reproduction data for 252 nests observed between 1979 and 2014 and assess a database of 1,620 sightings of 423 individually color-banded birds between 2004 and 2017. From the resighting data, we estimated annual apparent survival at two managed wetlands on O‘ahu using Cormack–Jolly–Seber models in program MARK. We found that Hawaiian gallinules have smaller mean clutch sizes than do other species in the genus Gallinula and that clutch sizes on Kaua‘i are larger than those on O‘ahu. The longest-lived bird in our dataset was recovered dead at age 7 y and 8 mo, and the youngest confirmed age at first breeding was 1 y and 11 mo. In 4 y of monitoring 14 wetland sites, we confirmed three interwetland movements on O‘ahu. In our pooled dataset, we found no statistically significant differences between managed and unmanaged wetlands in clutch size or reproductive success, but we acknowledge that there were limited data from unmanaged wetlands. Our best supported survival models estimated an overall annual apparent survival of 0.663 (95% CI = 0.572–0.759); detection varied across wetlands and study years. First-year survival is a key missing component in our understanding of the demography of Hawaiian gallinules. These data provide the foundation for quantitative management and assessment of extinction risk of this endangered subspecies.

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Section: Survival and Movementmentioning

confidence: 99%

Section: Survival and Movementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Estimation of Vital Rates for the Hawaiian Gallinule, a Cryptic, Endangered Waterbird

Rees

Chang

Cosgrove

et al. 2018

Journal of Fish and Wildlife Management

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“…We found Hawaiian Moorhen feather mass to be just below the 4% reported by Turček (1966) for a single moorhen (likely G. c. chloropus based on the location of the study). This result might be expected for a subspecies, like the Hawaiian Moorhen, that is weakly flighted (sensu McNab 2003, DesRochers et al 2009). The 4% also is lower than the 7% reported for three species of Anatidae (Turček 1966) that, like Hawaiian Moorhen, simultaneously molt their flight feathers (Hohman et al 1992, DesRochers et al 2009).…”

Section: Resultsmentioning

confidence: 64%

“…This result might be expected for a subspecies, like the Hawaiian Moorhen, that is weakly flighted (sensu McNab 2003, DesRochers et al 2009). The 4% also is lower than the 7% reported for three species of Anatidae (Turček 1966) that, like Hawaiian Moorhen, simultaneously molt their flight feathers (Hohman et al 1992, DesRochers et al 2009). It would be very instructive to compare the flight feather mass between this subspecies and a fully migratory subspecies, but data for that comparison are currently lacking.…”

Section: Resultsmentioning

confidence: 64%

Body Size, Growth, and Feather Mass of the Endangered Hawaiian Moorhen (Gallinula Chloropus Sandvicensis)

et al. 2010

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Feather corticosterone does not correlate with environmental stressors or body condition in an endangered waterbird

Gormally

Rees

Bowers

et al. 2020

Conservation Physiology

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Physiological metrics are becoming popular tools for assessing individual condition and population health to inform wildlife management and conservation decisions. Corticosterone assays can provide information on how animals cope with individual and habitat-level stressors, and the recent development of feather assays is an exciting innovation that could yield important insights for conservation of wild birds. Due to the widespread enthusiasm for feather corticosterone as a potential bioindicator, studies are needed to assess the ability of this technique to detect meaningful differences in physiological stress across a variety of stressor types and intensities. We examined feather corticosterone from 144 individuals among the 13 known breeding populations of Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered waterbird, on the island of O‘ahu. These ecologically independent subpopulations are known to have low genetic connectivity and movement rates and differ largely across a number of important conditions, including level of predator management, human disturbance, proximity to urban development and conspecific population density. This system is well suited for assessing the performance of feather corticosterone as a bioindicator of different known habitat-level threats common to this and many other conservation-reliant species. We found no statistically significant relationship between feather corticosterone and level of predator control, level of human disturbance, gallinule population density, percent urban cover or body condition across all sites despite the substantial difference in stressor magnitude in our dataset. We did find that gallinules in habitats with larger population densities were in worse body condition. These findings suggest that feather corticosterone is not a consistent indicator of anthropogenic impacts on populations. Furthermore, they suggest that feather corticosterone may be a poor bioindicator of known habitat-level threats for Hawaiian gallinules and that it should be used with caution in other avian taxa of conservation concern.

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Observations of Molt in an Endangered Rallid, the Hawaiian Moorhen

Cited by 7 publications

References 30 publications

Estimation of Vital Rates for the Hawaiian Gallinule, a Cryptic, Endangered Waterbird

Estimation of Vital Rates for the Hawaiian Gallinule, a Cryptic, Endangered Waterbird

Body Size, Growth, and Feather Mass of the Endangered Hawaiian Moorhen (Gallinula Chloropus Sandvicensis)

Feather corticosterone does not correlate with environmental stressors or body condition in an endangered waterbird

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