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.

Wedge-tailed Shearwater (Ardenna pacifica) nesting success in human-dominated coastal environments.

Many seabird populations are declining globally, but successful conservation efforts have led to population expansion of some species into human-dominated landscapes. Thus, there is an increased potential for direct human and seabird interactions for certain species in human-occupied areas, with nest-site characteristics potentially affecting the susceptibility of nests to human disturbance. We assessed the effect of human activity and nest-site characteristics on Wedge-tailed Shearwater (Ardenna pacifica, 'ua'u kani) nesting success at two breeding colonies, one with human exposure and one without, located in Kailua, O'ahu, Hawai'i. Human activity was measured by recording the frequency of people who entered a 5 m buffer around each nest. Nests were checked every two to three days to monitor nest success. The effect of human activity and nest-site characteristics on nesting success was determined using a variety of combinations of variables within binomial logistic regression models and AICc model selection. Nest-site characteristics among nests at both sites and human activity at the human-exposed site did not show a significant effect on nesting success. Our results suggest Wedge-tailed Shearwaters may experience some tolerance of human activity immediately around their nests-as long as burrow collapse does not occur. Given the small sample sizes and a single season of data collection, additional studies are needed to better understand the effect of human disturbance on Wedge-tailed Shearwaters. Infrastructure, such as fencing and signage, may be effective at reducing human-caused nest failure and may allow humans and disturbance-tolerant seabird species to coexist in shared coastal environments.

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.

How deaf American Sign Language/English bilingual children become proficient readers: an emic perspective.

A primary tenet underlying American Sign Language/English bilingual education for deaf students is that early access to a visual language, developed in conjunction with language planning principles, provides a foundation for literacy in English. The goal of this study is to obtain an emic perspective on bilingual deaf readers transitioning from learning to read to reading to learn. Analysis of 12 interactive, semi-structured interviews identified informal and formal teaching and learning practices in ASL/English bilingual homes and classrooms. These practices value, reinforce, and support the bidirectional acquisition of both languages and provide a strong foundation for literacy.