Hawaiian Stilt Research Articles

Predation of the endangered Ae'o (Hawaiian Stilt) by a native raptor, the Pueo (Hawaiian Short-eared Owl) on the island of O'ahu, Hawai'i, USA.

While the impact of introduced predators is a widely acknowledged issue and key component of conservation considerations for endemic waterbird populations in the Hawaiian Islands, the impact of native predators on endemic, endangered waterbirds is not as frequently discussed or factored into recovery models. The Pueo (Hawaiian Short-eared Owl; Asio flammeus sandwichensis) is a subspecies of Short-eared Owl endemic to the Hawaiian Islands and is State-listed as Endangered on the island of O'ahu. The Ae'o (Hawaiian Stilt; Himantopus mexicanus knudensi) is a subspecies of the Black-necked Stilt endemic to Hawai'i and is federally listed as Endangered throughout its range. A variety of non-native predators are confirmed to consume Ae'o eggs, chicks, and adults, including invasive mammals (e.g., feral cats), birds (e.g., Barn Owls), and amphibians (e.g., bullfrogs). While predation by native predators was suspected, there are no cases documented in the literature to date describing Pueo preying upon Ae'o. Here, we describe four events that provide evidence of Pueo predating Ae'o during the 2019-2021 breeding seasons in a wetland area on the island of O'ahu: (1) confirmed Pueo predating an Ae'o chick, (2) a suspected predation attempt of a Pueo chasing adult Ae'o, and (3) two suspected predation events based on (a) 10 adult-sized Ae'o carcasses and remains found near an active Pueo nest and (b) game camera photos of Pueo visiting two Ae'o nests. To our knowledge, these novel observations are the first published accounts of predator-prey interactions between these two subspecies.

A prioritization protocol for coastal wetland restoration on Molokaʻi, Hawaiʻi

Hawaiian coastal wetlands provide important habitat for federally endangered waterbirds and socio-cultural resources for Native Hawaiians. Currently, Hawaiian coastal wetlands are degraded by development, sedimentation, and invasive species and, thus, require restoration. Little is known about their original structure and function due to the large-scale alteration of the lowland landscape since European contact. Here, we used 1) rapid field assessments of hydrology, vegetation, soils, and birds, 2) a comprehensive analysis of endangered bird habitat value, 3) site spatial characteristics, 4) sea-level rise projections for 2050 and 2100 and wetland migration potential, and 5) preferences of the Native Hawaiian community in a GIS site suitability analysis to prioritize restoration of coastal wetlands on the island of Molokaʻi. The site suitability analysis is the first, to our knowledge, to incorporate community preferences, habitat criteria for endangered waterbirds, and sea-level rise into prioritizing wetland sites for restoration. The rapid assessments showed that groundwater is a ubiquitous water source for coastal wetlands. A groundwater-fed, freshwater herbaceous peatland or “coastal fen” not previously described in Hawaiʻi was found adjacent to the coastline at a site being used to grow taro, a staple crop for Native Hawaiians. In traditional ecological knowledge, such a groundwater-fed, agro-ecological system is referred to as a loʻipūnāwai (spring pond). Overall, 39 plant species were found at the 12 sites; 26 of these were wetland species and 11 were native. Soil texture in the wetlands ranged from loamy sands to silt and silty clays and the mean % organic carbon content was 10.93% ± 12.24 (sd). In total, 79 federally endangered waterbirds, 13 Hawaiian coots (‘alae keʻokeʻo; Fulica alai) and 66 Hawaiian stilts (aeʻo; Himantopus mexicanus knudseni), were counted during the rapid field assessments. The site suitability analysis consistently ranked three sites the highest, Kaupapaloʻi o Kaʻamola, Kakahaiʻa National Wildlife Refuge, and ʻŌhiʻapilo Pond, under three different weighting approaches. Site prioritization represents both an actionable plan for coastal wetland restoration and an alternative protocol for restoration decision-making in places such as Hawaiʻi where no pristine “reference” sites exist for comparison.

Hawaiian waterbird movement across a developed landscape

AbstractA key component for biologists managing mobile species is understanding where and when a species occurs at different locations and scaling management to fit the spatial and temporal patterns of movement. We established an automated radio‐telemetry tracking network to document multi‐year movement in 2016–2018 of 3 endangered waterbirds among wetlands on Oʻahu, Hawaiʻi, USA: ʻalae ʻula or Hawaiian gallinule (gallinule; Gallinula galeata sandvicensis), ʻalae keʻokeʻo or Hawaiian coot (coot; Fulica alai), and aeʻo or Hawaiian stilt (stilt; Himantopus mexicanus knudseni), each with different ecological requirements. There were marked differences in the movement propensity of the species, with no movement among sites detected in gallinules, 31% of coots moving among wetlands, and very high levels of daily movement in stilts. A network analysis revealed strong evidence for fidelity among individual stilts to specific wetlands, indicating different groups of wetlands supported different birds. There was also strong evidence for patterns in daily and seasonal movement patterns of stilts. Our work indicates the importance of each wetland to the waterbirds they support, as each individual had strong fidelity to a single wetland. In addition, for Hawaiian coots and stilts, which were documented moving among multiple wetlands, a network of wetlands may be key for long‐term persistence of these endangered species, and coordinated regional management of waterbirds as a shared resource could provide greater benefits to waterbirds than independent management of each wetland.

Successful nesting by 2 endangered Hawaiian waterbird species in a restored Indigenous wetland agroecosystem

The Hawaiian Stilt (Himantopus mexicanus knudseni) and Hawaiian Gallinule (Gallinula galeata sandvicensis) are federally endangered waterbirds endemic to the Hawaiian Islands. Both species are conservation-reliant; their population persistence is dependent on invasive predator control and removal of invasive plants that degrade habitat. We present observations of successful nesting by one Hawaiian Stilt pair and one Hawaiian Gallinule pair at a site managed within an adaptive Indigenous agroecological framework on the island of O‘ahu, Hawai‘i. The Hawaiian Stilt nest, found in February 2019, contained 4 eggs and produced 3 hatchlings, 2 of which were banded and monitored after hatching. The Hawaiian Gallinule nest, found in February 2020, contained 6 eggs and produced 5 hatchlings. Although no individuals were banded from this nest, 2 adults and 2 hatchlings were continuously observed in the nesting area after the eggs hatched. Lo‘i kalo Hawaiian wetland agroecosystems centered around the cultivation of kalo (taro; Colocasia esculenta), have the potential to expand Hawaiian waterbird habitat beyond state and federal protected areas. We are aware of unpublished accounts of Hawaiian waterbirds nesting in commercially farmed lo‘i kalo, but until now, there have been no previously published accounts of native waterbirds breeding in lo‘i kalo managed as Indigenous agroecosystems.

Distribution and Trends of Endemic Hawaiian Waterbirds

Four endemic species of wetland-dependent waterbirds occur on the main Hawaiian Islands, all of which have experienced sharp population declines and are listed as endangered species. Twice per year, state-wide surveys are conducted to count waterbirds, but these surveys are evaluated only infrequently. We used a state-space approach to evaluate long-term (1986–2016) and short-term (2006–2016) trends and current distribution and abundance of endemic Hawaiian waterbirds. The most numerous species was the Ae‘o, or Hawaiian Stilt (Himantopus mexicanus knudseni), with a 5-year estimated average abundance of 1,932 individuals, followed by ‘Alae Ke‘oke‘o, or Hawaiian Coot (Fulica alai), with 1,815 individuals, Alae ‘Ula, or Hawaiian Common Gallinule (Gallinula galeata sandvicensis) with 927 individuals, and the Koloa Maoli, or Hawaiian Duck (Anas wyvilliana) with 931 individuals. All four species had positive trends over the long-term, but short-term and island specific trends were more variable, and in some cases negative. These results provide valuable information to help guide management of Hawaii’s threatened and endangered endemic waterbirds.

Cooperative breeding behaviors in the Hawaiian Stilt (Himantopus mexicanus knudseni).

Cooperative breeding, which is commonly characterized by nonbreeding individuals that assist others with reproduction, is common in avian species. However, few accounts have been reported in Charadriiformes, particularly island‐nesting species. We present incidental observations of cooperative breeding behaviors in the Hawaiian Stilt (Himantopus mexicanus knudseni), an endangered subspecies of the Black‐necked Stilt (Himantopus mexicanus), during the 2012–2020 nesting seasons on the Hawaiian islands of O‘ahu and Moloka‘i. We describe two different behaviors that are indicative of cooperative breeding: (a) egg incubation by multiple adults; (b) helpers‐at‐the‐nest, whereby juveniles delay dispersal and reproduction to assist parents and siblings with reproduction. These observations are the first published accounts of cooperative breeding in this subspecies and merit further investigation, as cooperative breeding may improve population viability of the endangered, endemic Hawaiian Stilt.

Mammal-exclusion fencing improves the nesting success of an endangered native Hawaiian waterbird

Invasive predator control is often critical to improving the nesting success of endangered birds, but methods of control vary in cost and effectiveness. Poison-baiting or trapping and removal are relatively low-cost, but may have secondary impacts on non-target species, and may not completely exclude mammals from nesting areas. Mammal-exclusion fencing has a substantial up-front cost, but due to cost savings over the lifetime of the structure and the complete exclusion of mammalian predators, this option is increasingly being utilized to protect threatened species such as ground-nesting seabirds. However, non-mammalian predators are not excluded by these fences and may continue to impact nesting success, particularly in cases where the fence is designed for the protection of waterbirds, open to an estuary or wetland on one side. Thus, there remains a research gap regarding the potential gains in waterbird nesting success from the implementation of mammal-exclusion fencing in estuarine systems. In this study, we compared the nesting success of endangered Hawaiian Stilts (Ae‘o; Himantopus mexicanus knudseni) within a mammal-exclusion fence to that of breeding pairs in a nearby wetland where trapping was the sole means for removing invasive mammals. We predicted success would be greater for breeding pairs inside the exclusion fence and the hatchlings inside the enclosure would spend more time in the nesting area than hatchlings at the unfenced site. During a single breeding season following construction of a mammal-exclusion fence, we used motion-activated game cameras to monitor nests at two sites, one site with mammal-exclusion fencing and one site without. Clutch sizes and hatch rates were significantly greater at the fenced site than the unfenced site, but time spent by chicks in the nesting area did not differ between sites. These results add to the mounting body of evidence that demonstrates the effectiveness of mammal-exclusion fencing in protecting endangered birds and suggests it can aid endangered Hawaiian waterbirds toward recovery. These results also suggest that the single greatest predatory threat to the Hawaiian Stilt may be invasive mammals, despite a host of known non-mammalian predators including birds, crabs, turtles, and bullfrogs, as the complete exclusion of mammals resulted in significant gains in nesting success. As additional fences are built, future studies are necessary to compare nesting success among multiple sites and across multiple seasons to determine potential gains in fledging success and recruitment.

Seasonal patterns in nest survival of a subtropical wading bird, the Hawaiian Stilt (Himantopus mexicanus knudseni).

Nest survival is influenced by where and when birds decide to breed. For ground-nesting species, nest-site characteristics, such as vegetation height and proximity to water, may impact the likelihood of nest flooding or depredation. Further, habitat characteristics, and thus nest survival, may fluctuate across the breeding season. The Hawaiian Stilt (‘Ae‘o; Himantopus mexicanus knudseni) is an endangered Hawaiian waterbird that nests in wetlands across the Hawaiian Islands. In this study, we used observational surveys and nest cameras to examine the impact of nest-site characteristics and day of nesting season on nest survival of the Hawaiian Stilt. Early nests had a higher chance of survival than late nests. For most of the nesting season, taller vegetation was correlated with increased nest survival, while shorter vegetation was correlated with increased nest survival late in the nesting season. Seasonal patterns in nest survival may be due to changes in parental behavior or predator activity. Nest depredation was responsible for 55% of confirmed nest failures and introduced mammals were the primary nest predators. Our study is the first to examine seasonality in nest survival of Hawaiian Stilts and suggests that, despite longer nesting seasons and year-round occupation of wetlands, late nesters in subtropical regions may have lower nest survival than early nesters, similar to trends observed in temperate regions.

Multiple sources of evidence for density dependence in the endangered Hawaiian stilt (Himantopus mexicanus knudseni)

AbstractHawaiian stilts (Himantopus mexicanus knudseni) are an endangered subspecies of the Black‐necked stilt endemic to the Hawaiian Islands. Despite long‐term study, the main drivers of Hawaiian stilt population dynamics are poorly understood. We tested for density dependence using two sources of evidence: a 30‐year time series of annual estimated range‐wide abundance, and two 15+ year time series of reproductive success. Using separate methods with independent data, sources allowed us to make up for the potentially positive bias of one approach with the more conservative nature of the second. We compared nonlinear density‐dependent and density‐independent population model fits to our time‐series data, using both frequentist and Bayesian state‐space approaches. Across both approaches, density‐dependent models best fit observed population dynamics, with lower AICc and cross‐validation statistics compared to density‐independent models. Among density‐dependent models, a conditional model in which density‐independent dynamics occur below a population size threshold (~850–1,000 birds), and then density‐dependent dynamics occur above that threshold, performed best across Bayesian and frequentist model comparisons, with the Ricker model ranked next or equivalently. Our analysis of reproduction data revealed a strong negative effect of local adult density on nest success (proportion of nests hatching at least one chick) at Kealia National Wildlife Refuge on Maui, where few alternative breeding habitats are available, but no such effect at another site where many nearby alternative wetlands are available. These congruent results across independent datasets and analytical approaches support the hypothesis that Hawaiian stilts exhibit density dependence across their range.

Frequent Use of Upland Habitats by the Endangered Hawaiian Stilt (Himantopus mexicanus knudseni)

The Hawaiian Stilt, or Ae'o (Himantopus mexicanus knudseni), is an endangered waterbird endemic to the Hawaiian Islands. Loss of suitable wetland habitats due to anthropogenic development is a leading cause for decline, as well as the introduction of non-native predators and invasive wetland plants. This study fitted four Hawaiian Stilts with GPS satellite tags to document their use of wetland and surrounding habitats on Oahu Island. While other Hawaiian waterbirds are largely restricted to wetlands, we detected Hawaiian Stilts using heavily modified upland habitats, including developed areas, undeveloped fields, sports fields, as well as wetland habitats over a 6-month period. Overall, a high use of non-wetland habitat was observed (up to 58%), with significant differences in habitat occupancy among individual stilts and across different times of day. Wetlands were the dominant habitat occupied from morning to early afternoon, but non-wetland habitats were occupied at higher frequencies in the evening and early morning hours. Although only four birds were tracked, the extensive use of non-wetland habitat by these individuals indicates non-wetland habitats may be important for the conservation of this subspecies. However, more research is needed to understand how applicable these results are to other stilt populations across the Hawaiian Islands, and better understand the potential risks and benefits of these non-wetland habitats to stilt populations.

Combining watershed models and knowledge-based models to predict local-scale impacts of climate change on endangered wildlife

Climate change is expected to have significant impacts on native, threatened and endangered wildlife. Understanding and modeling these impacts useful for wildlife managers, however, remain difficult due to complex climate change, and costly and high data requirements. Consequently, we proposed an easily-interpretable and data-efficient decision support approach to understand climate change impacts on the abundance of three endangered wetland birds (Hawaiian Stilt, Hawaiian Coot and Hawaiian Moorhen). We coupled a watershed model, AnnAGNPS, and ecological models using fuzzy-cognitive mapping software, Mental Modeler, in Hanalei watershed, Kauaʻi. Results suggested that increased precipitation would increase Stilt abundance, but decrease Coot and Moorhen abundance. Decreasing precipitation might have negative effects for all three species. Moreover, decision-makers should pay equal attention to controlling components (water depth, food availability and disease) with system-wide influence. Finally, besides being adaptable to similar environmental contexts, our approach captured both direct and indirect climate change impacts through ecological connectivity.

Improving Bullfrog Capture Methods in Areas Managed for Hawaii's Endangered Endemic Waterbirds

American bullfrogs were introduced to Hawaii’s wetlands from California in the late 1800s. As in other areas where American bullfrogs have been introduced, these voracious predators threaten Hawaii’s native fauna. Of particular concern are Hawaii’s federally endangered endemic waterbirds: the Hawaiian stilt, Hawaiian coot, Hawaiian gallinule, and Hawaiian duck. Wetland managers in Hawaii control bullfrogs for the benefit of these endangered waterbirds. The U.S. Fish and Wildlife Service manages several core wetlands on national wildlife refuges in Hawaii that are necessary for survival of the waterbirds. These refuges include bullfrog control as a management strategy. Unpublished studies on James Campbell National Wildlife Refuge have documented bullfrogs as a major predator of newly hatched endangered waterbird chicks. This refuge currently maintains a year-round bullfrog trapping program with increased effort in the spring during the peak of waterbird breeding. Existing trapping methods employ a simple fish-style funnel trap with red flagging used as an attractant. As part of an effort to improve efficacy of current bullfrog capture methods, we investigated the effectiveness of different attractants for the traps. In addition to the current attractant of red flagging, we tested light, bullfrog call acoustic recordings, and life-size bullfrog decoys. The results showed that most of the treatments were no more effective than the control (no attractant). If we can improve bullfrog trap yields, we expect greater chick survival for the endangered Hawaiian waterbirds.

Application of the complete‐data likelihood to estimate juvenile and adult survival for the endangered Hawaiian stilt

AbstractApplied ecologists routinely use demographic models to predict population trajectories. Survival rates throughout the life cycle, which are required for these models, are often difficult to obtain, especially for long‐lived or mobile species. Detailed information for pre‐adult age classes in particular is often lacking. Using a 20‐year dataset from several hundred individuals, we used Markov chain Monte Carlo methods to fit hierarchical models that describe survival rates for both adult and sub‐adult Hawaiian stilts Himantopus mexicanus knudseni, an endangered island endemic. We constructed the complete‐data likelihood and used data augmentation to estimate missing values and incorporate data that were not collected during formal sampling. Survival estimates were lower and more uncertain during the first 2 months of life compared with the remainder of the first year. The probability of first‐year survival averaged 0.55 (95% credibility interval: 0.07–0.90), but varied considerably among cohorts from different years and islands. Probability of adult annual survival differed little between females (0.79; 0.71–0.86) and males (0.80; 0.72–0.87), but increased as birds aged from 1 to 20 years (0.77–0.85). Our analysis confirms that earlier work, despite being based on few data, provided good point estimates for survival rates. Our new analysis, however, provides the first comprehensive assessment of uncertainty in survival rates and detailed information on the nature of variation in first‐year and adult survival. This information will help inform new demographic models and can be used to guide management actions.

Non-native Mammalian Predator Control to Benefit Endangered Hawaiian Waterbirds

Hawai‘i’s wetlands are inhabited by 5 endangered endemic waterbird species: the Hawaiian stilt (ae‘o), Hawaiian coot (‘alae ke‘oke‘o), Hawaiian duck (koloa maoli), Hawaiian goose (nēnē), and Hawaiian gallinule/Moorhen (‘alae ‘ula). One of the biggest threats facing these waterbirds is predation by non-native mammalian predators. Non-native cats, rats, and mongooses all directly depredate either eggs, young, or adult birds. Control of these predators is a key component of the active management strategy employed to recover Hawaiian waterbirds. Predator control efforts have included live or kill traps, rodenticide bait stations, and fences in areas important for the waterbirds. To evaluate the success of these predator control efforts on key wetland national wildlife refuges in Hawai‘i, we explored 4 metrics: live trap capture history, rodent and mongoose presence/absence using track tunnels, waterbird population densities, and waterbird reproductive success. The track tunnel data documented lower predator density within the predator control areas. The live trapping capture history data showed strong spatial patterns of higher success along perimeter fence lines and limited success within the interior of the wetlands. We also found that areas receiving predator control had both higher reproductive success and, in most cases, greater waterbird population densities. These findings support mammalian predator control as a key management strategy to promote recovery of these endangered species.

Managing Conservation Reliant Species: Hawai'i's Endangered Endemic Waterbirds

Hawai'I's coastal plain wetlands are inhabited by five endangered endemic waterbird species. These include the Hawaiian Coot ('alae ke'oke'o), Hawaiian Duck (koloa maoli), Hawaiian Stilt (ae'o), Hawaiian Gallinule (Moorhen) ('alae 'ula), and Hawaiian Goose (nēnē). All five species are categorized as being “conservation reliant.” The current strategy to recover these endangered birds includes land protection and active management of wetlands. To assess the effectiveness of the current management paradigm, we compared species population trends across the state to those on six actively managed wetland national wildlife refuges (Refuges) thought to be critical for the survival of these endangered species. To perform the evaluation we relied on systematic semiannual population counts that have been conducted across most wetlands in the state and monthly population counts that have occurred on Refuges during the same time period. We found that statewide and Refuge populations of the Hawaiian Coot, Stilt and Gallinule have rebounded from historic lows and over the last 20 years have slowly increased or remained stable. We also documented that Refuges are important to each species year-round and that a disproportionately larger percentage of the population for each species is found on them. Understanding of why Refuges successfully house a disproportionate percentage of these “conservation reliant” species can inform current and future conservation efforts as well as ensure long-term population viability for these species.

Long‐term population trends of endangered Hawaiian waterbirds

AbstractWe analyzed long‐term winter survey data (1956–2007) for three endangered waterbirds endemic to the Hawaiian Islands, the Hawaiian moorhen (Gallinula chloropus sandvicensis), Hawaiian coot (Fulica alai), and Hawaiian stilt (Himantopus mexicanus knudseni). Time series were analyzed by species–island combinations using generalized additive models, with alternative models compared using Akaike information criterion (AIC). The best model included three smoothers, one for each species. Our analyses show that all three of the endangered Hawaiian waterbirds have increased in population size over the past three decades. The Hawaiian moorhen increase has been slower in more recent years than earlier in the survey period, but Hawaiian coot and stilt numbers still exhibit steep increases. The patterns of population size increase also varied by island, although this effect was less influential than that between species. In contrast to earlier studies, we found no evidence that rainfall affects counts of the target species. Significant population increases were found on islands where most wetland protection has occurred (Oahu, Kauai), while weak or no increases were found on islands with few wetlands or less protection (Hawaii, Maui). Increased protection and management, especially on Maui where potential is greatest, would likely result in continued population gains, increasing the potential for meeting population recovery goals.

Life-history and viability analysis of the endangered Hawaiian stilt

The Hawaiian stilt Himantopus mexicanus knudseni is an endangered, endemic subspecies of black-necked stilt. We present life-history data required to perform population viability analysis (PVA), and the results of a series of PVAs under two scenarios, treating (a) the subspecies as a single population, and (b) six subpopulations as a metapopulation. We performed sensitivity analyses on model parameters and used results to address various management options. Both basic models predicted that stilts would increase to fill available habitat with no chance of a significant decline. Catastrophe, maximum age, and density-dependent reproduction had little effect on population projections. Rapid declines in the probability of stilt populations persisting occurred when clutch failure rate or first-year mortality rate increased above 70%, or when adult mortality rate increased above 30%. Model predictions of mean population size at 200 years tracked changes in carrying capacity. If current conditions change such that rates of clutch failure or stilt mortality increase, population declines and eventual extinction becomes more likely. Managers, therefore, should maintain predator control, limit water level fluctuations, and maintain current habitat area. Downlisting is not warranted because wetland management and predator control are necessary for Hawaiian stilts to persist.

Mangroves as Alien Species: The Case of Hawaii

Prior to the early 1900s, there were no mangroves in the Hawaiian Archipelago. In 1902, Rhizophora mangle was introduced on the island of Molokai, primarily for the purpose of stabilizing coastal mud flats. This species is now well established in Hawaii, and is found on nearly all of the major islands. At least five other species of mangroves or associated species were introduced to Hawaii in the early 1900s, and while none has thrived to the degree of R. mangle, at least two have established self-maintaining populations (Bruguiera gymnorrhiza and Conocarpus erectus). Mangroves are highly regarded in most parts of the tropics for the ecosystem services they provide, but in Hawaii they also have important negative ecological and economic impacts. Known negative impacts include reduction in habitat quality for endangered waterbirds such as the Hawaiian stilt (Himantopus mexicanus knudseni), colonization of habitats to the detriment of native species (e.g. in anchialine pools), overgrowing native Hawaiian archaeological sites, and causing drainage and aesthetic problems. Positive impacts appear to be fewer, but include uses of local importance, such as harvesting B. gymnorrhiza flowers for lei-making, as well as some ecological services attributed to mangroves elsewhere, such as sediment retention and organic matter export. From a research perspective, possible benefits of the presence of mangroves in Hawaii include an unusual opportunity to evaluate their functional role in coastal ecosystems and the chance to examine unique or rare species interactions.

The Incubation Period of the Hawaiian Stilt

The Incubation Period of the Hawaiian Stilt

The Hawaiian Stilt

These photographs of the graceful Hawaiian Stilt, Himantopus himantopus knudseni, constitute a pictorial record of one of the world's vanishing birds. In 1944, Mr. George Munro of Honolulu (Birds of Hawaii, Tongg Publ. Co., Honolulu) estimated only 200 stilts were left in the Hawaiian Islands. We believe, that in spite of its dwindling habitat, the closed hunting season on the Islands during the recent war and its continuation for stilts permitted the population to increase to approximately 1,000 birds by 1946-1947 (Schwartz and Schwartz, The Game Birds in Hawaii, Bd. Agric. and For., Honolulu, 1949). The Hawaiian Stilt maintains its largest numbers on the island of Oahu where its best habitat exists. Smaller flocks occur on Niihau, Kauai, and Maui islands, and possibly some may use the island of Molokai. Our limited observations did not ascertain the permanency of the stilt population on each island, but reports by local inhabitants indicate possible movements between islands. We have observed considerable daily shifting of the flocks between different locales on each island. Stilts frequent the coastal mud flats and the fresh and brackish marshy areas and shallows of reservoirs, lakes, and ponds. The vegetative types most commonly associated with this habitat are great bulrush, Scirpus validus, american saltwort, Batis maritinia, and various grasses. In spite of the upward trend of the stilt population, the future of this species is not bright since the habitat it prefers is rapidly disappearing due to the reclamation of such areas for civic and military purposes. Illegal kill still constitutes a limiting factor. Two adult Hawaiian Stilts were confiscated on April 6, 1947, from a hunter. They measured as follows: