DOI: 10.5061/dryad.pvmcvdntr
title: Hawaiian gallinule vital rate data from O'ahu and Kaua'i: Reproduction and survival data from an endangered bird

description: Where stable source populations of at-risk species exist, translocation
 may be a reasonable strategy for re-establishing extirpated populations.
 However, the success rates of such efforts are mixed, necessitating
 thorough preliminary investigation. Stochastic population modeling can be
 a useful method of assessing the potential success of translocations.
 Here, we report on the results of modeling translocation success for the
 Hawaiian Common Gallinule (‘alae ‘ula; Gallinula galeata sandvicensis), an
 endangered waterbird endemic to the Hawaiian Islands. Using updated vital
 rates, we constructed a model simulating three existing extant (wild)
 source populations and a hypothetical recipient site on another island. We
 then projected the effects of six different translocation scenarios and
 sensitivity of the results to variation of three important demographic
 parameters on the probability of extinction (PE) of the reintroduced and
 donor populations. Larger translocations, of at least 30 birds, had low
 probability of extinction in the reintroduced population, but raised
 extinction risk of the smallest source population. Spacing out
 translocations in time (e.g., 10 birds translocated in total in three
 installments over nine years), led to lower PE than translocating all
 individuals at once (i.e., bulk translocations) for both the source and
 reintroduced populations. Brood size and hatch-year juvenile survival had
 a disproportionate impact on reintroduced population viability.
 Importantly, the reported juvenile survival rate is very near the
 threshold for population failure. This suggests that post-introduction and
 subsequent management of wetlands, particularly predator control, could be
 critical to reintroduction success. We recommend that individuals should
 be translocated from multiple, genetically distinct subpopulations to
 reduce the possibility of inbreeding depression. Based on this analysis,
 the recipient wetland should be sufficiently large that it can support at
 least 25 pairs of gallinules. Based on recent estimates of population
 densities on O‘ahu, such a wetland would need to be between 3.75-74.6 ha.
 Where stable source populations of at-risk species exist, translocation
 may be a reasonable strategy for re-establishing extirpated populations.
 However, the success rates of such efforts are mixed, necessitating
 thorough preliminary investigation. Stochastic population modeling can be
 a useful method of assessing the potential success of translocations.
 Here, we report on the results of modeling translocation success for the
 Hawaiian Common Gallinule (‘alae ‘ula; Gallinula galeata sandvicensis), an
 endangered waterbird endemic to the Hawaiian Islands. Using updated vital
 rates, we constructed a model simulating three existing extant (wild)
 source populations and a hypothetical recipient site on another island. We
 then projected the effects of six different translocation scenarios and
 sensitivity of the results to variation of three important demographic
 parameters on the probability of extinction (PE) of the reintroduced and
 donor populations. Larger translocations, of at least 30 birds, had low
 probability of extinction in the reintroduced population, but raised
 extinction risk of the smallest source population. Spacing out
 translocations in time (e.g., 10 birds translocated in total in three
 installments over nine years), led to lower PE than translocating all
 individuals at once (i.e., bulk translocations) for both the source and
 reintroduced populations. Brood size and hatch-year juvenile survival had
 a disproportionate impact on reintroduced population viability.
 Importantly, the reported juvenile survival rate is very near the
 threshold for population failure. This suggests that post-introduction and
 subsequent management of wetlands, particularly predator control, could be
 critical to reintroduction success. We recommend that individuals should
 be translocated from multiple, genetically distinct subpopulations to
 reduce the possibility of inbreeding depression. Based on this analysis,
 the recipient wetland should be sufficiently large that it can support at
 least 25 pairs of gallinules. Based on recent estimates of population
 densities on O‘ahu, such a wetland would need to be between 3.75-74.6 ha.
description: <strong>Reproductive rate data
 (HAGAVitalRates_9-10-23_Export)</strong> We
 acquired nest data from recent monitoring projects run through the state
 of Hawaii Department of Land and Natural Resources, Division of Forestry
 and Wildlife (DOFAW) on O‘ahu, and graduate dissertation work conducted at
 Hanalei National Wildlife Refuge on Kaua‘i (by BW). Nests on O‘ahu were
 located during routine weekly or biweekly surveys using an
 area-search survey. A team of 3–7 observers walked meandering transects
 with the goal of locating all nests in a given area. All nests were
 visually checked 2 times per week until hatching or failure. DOFAW nest
 monitoring continued throughout the annual cycle. A
 subset of Hawaiian Gallinule nests on O‘ahu was monitored from January
 through December 2020–2023. All nests were visually checked at least twice
 weekly, and a subset was monitored from January through December 2020–2023
 using SPYPOINT Solar Dark (GG Telecom, Quebec, Canada) passive infrared
 cameras (trigger speed: 0.07 s) placed about 1 m from the nest, mounted on
 a 7.6 cm wide metal post 1.8 m long, fixed with a fully adjustable camera
 mount that allows a camera angle of 0–90. Cameras were programmed to take
 2 images back-to-back immediately upon infrared motion activation. Cameras
 were programmed to take photos instantly for each activation (Instant
 setting recovery speed: 0.3 s). Cameras were checked weekly for battery
 life and SD card data retrieval and were removed either immediately after
 a nest was<br>confirmed failed or after a nest was
 confirmed successful. A nest was considered successful
 if at least 1 egg hatched and was considered failed if the eggs all
 disappeared before the expected hatch date or if signs of predation (e.g.,
 predator scat/tracks in the nest or destroyed eggs adjacent to the nest),
 flooding (e.g., intact eggs outside nest following an increase in water
 level or nest submerged under water), or abandonment (e.g., eggs cold
 to the touch in the morning, hot to the touch in the afternoon) were
 apparent. On Kaua‘i, nests were found by conducting
 systematic searches. In wetland units managed strictly for waterbirds,
 transects spaced 10 m apart were walked, while in taro that was grown on
 the refuge searches were done by walking the pond perimeter. Although
 Hawaiian Gallinules can nest year-round (Shallenberger 1977, Byrd and
 Zeillemaker 1981), searches were concentrated during the main breeding
 season. Nests also were found incidentally during regular activities by
 refuge staff and taro farmers. Nests on Kaua‘i were monitored with and
 without cameras (see Webber 2022 for details of monitoring and assessment
 of nest fates). All nests were checked every 3–5 d to monitor nest status;
 if the brood continued to use the nest after hatching and the camera was
 available, monitoring continued for brood survival data.
 <strong>Brood Survival Data
 (BroodDatabase_8-24-22)</strong>  Due to some
 methodological differences in brood monitoring among datasets compiled in
 this study, we resampled data to a matching, lowest common temporal
 resolution. Brood data from Keawawa wetland (O‘ahu) were recorded via
 multiple daily surveys for the first 60þ d posthatch by a group of trained
 citizen science volunteers. Brood encounter data on Kaua‘i were collected
 based on 4 d encounter intervals, recording presence and number of chicks
 if the brood was detected on any day within the interval. All brood
 records in our Kaua‘i dataset were collected by BW, and they were
 monitored by surveying telemetered adults (see Webber 2022 for details).
 Territories with known nests were monitored starting at what was estimated
 to be mid-incubation, and visited at least once every 4 d. At James
 Campbell National Wildlife Refuge (O‘ahu), brood encounters were
 opportunistic. Except for data from Keawawa, most brood monitoring ended
 after the first month post-hatch. Based on these data formats, we reduced
 our combined data to 4 d intervals and the first 30 d post-hatch to avoid
 estimating parameters with a sparse dataset.
description: # Hawaiian gallinule vital rate data from O'ahu and Kaua'i -
 Reproduction and Survival data from an endangered bird
 [https://doi.org/10.5061/dryad.pvmcvdntr](https://doi.org/10.5061/dryad.pvmcvdntr) Two excel sheets with data formatted for use in Program MARK and import into R. First has encounter histories of HAGA broods surveyed in three locations (see manuscript). Second has raw vital rate data from HAGA nests encountered at several sites on two islands (see manuscript for details)  ## Description of the data and file structure **Reproductive rate data (HAGAVitalRates_9-10-23_Export)** This includes information on Hawaiian gallinule nests that were discovered and monitored at multiple sites in Hawaii. Explanation of individual data columns below.  **File Columns** \**Nest ID - **ID of the nest \**Year **- Year of survey **Island** - Island on which data were collected **No.** Eggs - Number of eggs **No. Chicks** - Number of hicks if any **Nest success 1.0** - Whether nest was successful in hatching chicks, 1 as success 0 as failure **Protected 1.0** - Whether nest site was legally protected, 1 as yes 0 as no **Source** - Source of data (collectors and or institution) **NOTE:** NA's imply missing data. In other words, these data were not available to the compilers of the data despite follow-up questioning of data collectors in the field.    **Brood Survival Data (BroodDatabase_8-24-22)**  File shows encounter histories of individual broods of Hawaiian gallinules discovered and monitored at various sites on the Hawaiian islands. In each case, a count is given of the number of individual chicks encountered if the site was visited over a 4-day period. Where no visit was conducted, ".." is used.  Data are prepared in the Lukacs brood survival format for use in Program MARK. See Lukacs PM, Dreitz VJ, Knopf FL, Burnham KP. 2004. Estimating survival probabilities of unmarked dependent young when detection is imperfect. Condor. 106:926–31. **File Rows** **Day no.** - Four-day period since brood discovery. If the location was visited, or parents seen, within the four-day period since first encounter (brood discovery), a number is presented, where "00" means no chicks detected, "01" means one chick detected, and so on. ".." means that the brood was not visited in the next 4-day period.  **All other rows** - code names of individual broods. First six (rows 2-17) are from Keawawa, all others from Kaua'i. Data format requires a 0 before the number of observed chicks, hence all numbers are "00" "01" etc. Cells with ".." indicate that no survey was conducted.  ## Sharing/Access information Not to be used without permission from the co-authors. Please contact corresponding author CB van Rees with questions.  ## Code/Software None