Abstract The Hawaiian Islands, an isolated archipelago more than 3000 kilometres from the nearest continent, are widely recognized as one of the best places to study causal mechanisms driving evolutionary change. Moreover, the clock-like production of new islands, each with known and discrete geological ages, makes investigating how palaeogeological factors may influence species diversity particularly tractable. Here, we investigate phylogeny, divergence times, and intraspecific variation within an endemic Hawaiian bird lineage, the ʻelepaio (Aves: Chasiempis). We employed a Bayesian phylogenetic model that simultaneously accounts for lineage diversification, paleogeographic history, and molecular evolution to estimate divergence times. By utilizing information regarding the proximity of islands in different geologic epochs and the geologic age of island emergence, this process-based model allows for inference of time-calibrated phylogenies in cases that lack suitable fossil calibrations, as is common on oceanic islands. Using Ultraconserved Element (UCE) data, we recover a history for ‘elapaio that involves divergence from other Pacific Island lineages followed by colonization of the Hawaiian archipelago within the past several million years. Intraspecific sampling from thousands of loci provides further support for the recognized three species arrangement for the clade, with no evidence of intraspecific structure.

This is the second report of the Hawaii Bird Records Committee (HBRC). From 2019 to 2024, the HBRC reviewed 37 reports involving 29 bird species, of which 34 reports of 26 species were accepted, two were rejected, and one required recirculation and is still under review. The accepted reports included 15 species new to the Hawaiian Islands, eight second records, one third record, and one sixth record. Two more species were added because of splits to taxa that had been recorded previously. Through 2024, the Hawaiian Islands bird checklist includes 355 species.

The Brown–Cocos Booby complex occurs in tropical and subtropical oceans worldwide and consists of five named taxa. The Cocos Booby (Sula brewsteri), including the subspecies brewsteri, etesiaca, and nesiotes, was split recently from the Brown Booby (Sula leucogaster), which retains the subspecies leucogaster and plotus. Because information about their field identification is limited, especially for females, I evaluated characters distinguishing the five taxa by examining 50 museum specimens and photos of 754 living Cocos and Brown Boobies from 47 locations in the ranges of all five subspecies. The Cocos and Brown Boobies can be distinguished by at least five characters: head color, pattern of the underwing coverts, iris darkness, culmen concavity, and bill color, the importance of which differ by sex and in some cases by subspecies. The white on the head and neck of the male Cocos Booby, which varies by subspecies, is the most obvious difference from the Brown Booby. Female Cocos Boobies also have the head paler brown than in female Brown Boobies. The Cocos Booby has a darker iris and more brown in the underwing coverts. Sula leucogaster plotus has a straighter culmen and females have the bill yellow rather than pink, as in all other taxa. The extent of white on the neck of male Cocos Boobies in the Revillagigedo Islands identifies them as nesiotes rather than as brewsteri. Information about individuals that have dispersed outside the traditional range helps track their movements and in assessing effects of environmental changes on populations.

In the 1960s and 1970s, Laysan Albatrosses Phoebastria immutabilis colonized several sites in the Pacific from which they had been extirpated or had not been known to nest previously, including the US Navy's Pacific Missile Range Facility (PMRF) on Kaua'i, Hawai'i, USA, where they increased to become a bird aircraft strike hazard (BASH). To reduce their population at PMRF, albatross eggs were destroyed or removed as part of a BASH reduction program until 2005, when an alternate plan was devised by the Navy, US Fish and Wildlife Service, and US Department of Agriculture Wildlife Services, in which eggs from PMRF were placed in foster nests at other colonies on Kaua'i where the natural egg was infertile or had died. During 2009-2022, we placed 500 eggs from PMRF in foster nests on Kaua'i and the Hawaiian island of O'ahu. The egg viability rate in all colonies was 73% and varied among years. The hatching rate of foster eggs was 53%, fledging rate was 72%, and overall reproductive success was 38%, rates that were slightly lower than in natural eggs at the same sites. This project resulted in 189 fledged Laysan Albatross that otherwise would have died, and it helped solve a human-wildlife conflict. Several useful management techniques and egg translocation methods were developed during this project that can be used in similar projects with other seabirds.

Laysan Albatross ( Phoebastria immutabilis) fledged the first chick on the island of O'ahu in 1947, but did not begin regularly breeding until 1992, followed by Black-footed Albatross (P. nigripes) who began breeding in 2022. Laysan Albatross have attempted to breed at nine locations on O'ahu since 1979 and have established colonies at four sites: Ka'ena Point, Kuaokala-, Kahuku Point, and James Campbell National Wildlife Refuge. We monitored Laysan Albatross colonies on O'ahu weekly from 2004 to 2023; all individuals were censused, banded, and identified to gender. There was a population of 875 adults on O'ahu in 2023, 490 of which were active breeders. The annual growth rate up to 2015 was 26%, but the growth rate slowed to 20% after human vandalism in 2015 that resulted in the destruction of 17 nests and at least 17 adults. The advent of predator exclusion fencing at Ka'ena Point (2011) and Kuaokala- (2021) resulted in increased reproductive success (from 0.37 to 0.43) driven by a 25% increase in chick fledging success (from 0.60 before fencing to 0.80 after) which resulted in an estimated additional 69 chicks fledging compared to if the fence had not been constructed. Black-footed Albatross visits increased to O'ahu from 3 in 2017 to 317 in 2023, coinciding with the disappearance of East Island in Papaha-naumokua-kea Marine National Monument which displaced 2,000 breeding pairs. These new colonies are at higher elevations and will continue to serve as refugia against sea level rise and as such, are conservation priorities.

Background Invasive species are the primary threat to island ecosystems globally and are responsible for approximately two-thirds of all island species extinctions in the past 400 years. Non-native mammals—primarily rats, cats, mongooses, goats, sheep, and pigs—have had devastating impacts on at-risk species and are major factors in population declines and extinctions in Hawaiʻi. With the development of fencing technology that can exclude all mammalian predators, the focus for some locations in Hawaiʻi shifted from predator control to local eradication. Methods This article describes all existing and planned full predator exclusion fences in Hawaiʻi by documenting the size and design of each fence, the outcomes the predator eradications, maintenance issues at each fence, and the resulting native species responses. Results Twelve predator exclusion fences were constructed in the Hawaiian Islands from 2011–2023 and six more were planned or under construction; all were for the protection of native seabirds and waterbirds. Fences ranged in length from 304–4,877 m and enclosed 1.2–640 ha. One-third of the 18 fences were peninsula-style with open ends; the remaining two-thirds of the fences were complete enclosures. The purpose of twelve of the fences (67%) was to protect existing bird populations, and six (33%) were initiated for mitigation required under the U.S. Endangered Species Act. Of the six mitigation fences, 83% were for the social attraction of seabirds and one fence was for translocation of seabirds; none of the mitigation fences protected existing bird populations. Rats and mice were present in every predator exclusion fence site; mice were eradicated from five of six sites (83%) where they were targeted and rats (three species) were eradicated from eight of 11 sites (72%). Mongoose, cats, pigs, and deer were eradicated from every site where they were targeted. Predator incursions occurred in every fence. Rat and mouse incursions were in many cases chronic or complete reinvasions, but cat and mongoose incursions were occasional and depended on fence type (i.e., enclosed vs. peninsula). The advent of predator exclusion fencing has resulted in great gains for protecting existing seabirds and waterbirds, which demonstrated dramatic increases in reproductive success and colony growth. With threats from invasive species expected to increase in the future, predator exclusion fencing will become an increasingly important tool in protecting island species.

Laysan (Phoebastria immutabilis) and Black-footed Albatrosses (P. nigripes) nest primarily on low-lying atolls in the Northwestern Hawaiian Islands that are threatened by inundation from sea level rise and increasing storm surge associated with climate change. Restoration or creation of breeding colonies on higher islands is among the highest priority conservation actions for these species. A previous structured decision-making analysis identified the California Channel Islands as a possible restoration site for Black-footed Albatross. The California Current is part of the natural foraging ranges of Laysan and Black-footed albatrosses. Archaeological evidence indicates both species were present in the California Channel Islands prehistorically, yet neither currently nests in the Channel Islands. We assessed the feasibility of creating albatross breeding colonies in the Channel Islands using social attraction and translocation, and the suitability of each island. We used a risk analysis framework developed for the U.S. National Park Service to evaluate the potential ecological risks of this action. Creating an albatross colony in the Channel Islands is feasible using available methods. Santa Barbara and San Nicolas islands would be most suitable for albatross. Social attraction is less expensive and might be effective for creating a Laysan Albatross colony because that species is already visiting some islands. Translocation would be necessary to create a Black-footed Albatross colony. The risks associated with attempting to establish albatross breeding colonies in the Channel Islands were deemed to be generally low, but the risk of no action is high to these albatrosses. This can be a useful assisted colonization case study that can inform decisions by land managers and agencies regarding conservation of North Pacific albatrosses and other species.

Oceanic seabirds have suffered population declines and extirpations due to human disturbance and still face multiple threats. Here, we assessed the potential genetic vulnerability of the red-tailed tropicbird, Phaethon rubricauda , a seabird species threatened by human disturbance and listed as ‘least concern’ by the IUCN. Using Single Nucleotide Polymorphisms (SNPs) we evaluated the genetic population structure of the red-tailed tropicbird throughout the Pacific Ocean using samples from 132 individuals from six islands. We sampled individuals from islands without human-related disturbance (non-impacted islands) and with human-related disturbance (impacted islands). Results of genome-wide SNP analyses were consistent with previous results using mitochondrial DNA sequences analyses. Genetic diversity did not differ between impacted and non-impacted islands, and low inbreeding estimates were detected for all colonies. The SNPs analyses confirmed a pattern of isolation by distance and significant inter-regional (Chile, Australasia, and Hawaiʻi) genetic structure, but revealed greater differentiation of tropicbirds in Hawaiʻi compared with Chile and Australasia. Within regions, our results further indicated significant differentiation between Rapa Nui and Salas & Gómez Island (Chile), and between Meyer and Phillip islands (Australasia) that was not detected using mitochondrial DNA analyses. Within Hawaiʻi, we found a lack of significant genetic differentiation between Oʻahu and Kauaʻi, separated by 200 km. Our findings indicated that red-tailed tropicbird colonies are at genetic risk due to limited dispersal among colonies which may reduce the fitness of the species in the long-term. We suggest that red-tailed tropicbird colonies are vulnerable to future population declines because recovery through immigration from other islands may be limited by geographic distance. Conservation actions will help preserve genetic diversity and discrete populations for this native seabird at colonies throughout the Pacific.

Translocations of chicks are increasingly being used in seabird restoration projects, along with social attraction of adults using acoustic and visual cues, to establish new colonies or re-establish extirpated colonies. Many seabird species exhibit high rates of natal philopatry, where most chicks return to the nesting colonies from which they fledged. This makes them ideal candidates for translocation projects since they have a high likelihood of returning to translocation sites if they are relocated prior to imprinting on a natal site. Starting in 2017, Black-footed Albatross (BFAL) chicks were translocated from populations in the low-lying Northwestern Hawaiian Islands, where they face habitat loss due to sea level rise, to the higher elevation island of O'ahu, in an attempt to establish a new colony for this species. Additionally, social attraction was utilized at the site to attract potential nesting adults and provide social stimuli for the translocated chicks. Our study examined the response of translocated BFAL chicks to visual and audio stimuli inside a mammalian predator exclusion fence at James Campbell National Wildlife Refuge on the island of O'ahu. Decoys constructed in two different poses, representing courtship and resting postures of adult BFAL, were placed in various combinations with playback speakers around the perimeter of artificial shelters. Motion-activated cameras were used to record and compare the number of visits by chicks to different combinations of visual and acoustic stimuli. We found the number of visits was highest at setups that included a combination of a decoy pair and a playback speaker, suggesting that a combination of visual and audio cues of adult BFAL are most attractive to the chicks. Future studies are needed to evaluate the long-term impacts of exposure to artificial visual and audio stimuli as chicks on return rates to translocation site and social behavior as adults.

Seabird conservation is a large and complex subject that involves a variety of biotic, abiotic, and societal factors. The regulatory and legal aspects of seabird conservation underlie virtually all efforts worldwide. Policy and regulations, driven by evidence-based science, are needed to properly manage the resources we want to protect and as a result, seabird biologists need to be well versed on policy and legislation. At the intersection of science and management lies the “knowing-doing” gap that results between research and real-world action. Taxonomically, several trends were apparent. Orders of birds that comprised exclusively of marine species were the most impacted, with 72% of penguins and 63% of Procellariiformes (albatrosses, petrels, and shearwaters) having an elevated conservation status with the IUCN. There also were biogeographical patterns in conservation interventions since tropical and temperate seabirds differ in many life history characteristics, which in turn influence how best to prioritize and implement conservation actions. Monitoring of seabird population size, distribution, and trend was discussed in almost every chapter as being fundamental toward understanding threats and the effectiveness of solutions. Without baseline knowledge of these parameters, it is impossible to track the success of interventions. The most pervasive pattern that came up in all chapters was the ubiquitous effect of climate change on seabirds and their conservation and that mitigating, and accounting for this threat will influence the outcome of all other interventions. We are poised at the cusp to be able to prevent the extinction of these magnificent animals if we can collectively overcome the barriers to implementing these solutions.

The global loss of biodiversity has inspired actions to restore nature across the planet. Translocation and social attraction actions deliberately move or lure a target species to a restoration site to reintroduce or augment populations and enhance biodiversity and ecosystem resilience. Given limited conservation funding and rapidly accelerating extinction trajectories, tracking progress of these interventions can inform best practices and advance management outcomes. Seabirds are globally threatened and commonly targeted for translocation and social attraction (“active seabird restoration”), yet no framework exists for tracking these efforts nor informing best practices. This study addresses this gap for conservation decision makers responsible for seabirds and coastal management. We systematically reviewed active seabird restoration projects worldwide and collated results into a publicly accessible Seabird Restoration Database. We describe global restoration trends, apply a systematic process to measure success rates and response times since implementation, and examine global factors influencing outcomes. The database contains 851 active restoration events in 551 locations targeting 138 seabird species; 16% of events targeted globally threatened taxa. Visitation occurred in 80% of events and breeding occurred in 76%, on average 2 y after implementation began (SD = 3.2 y). Outcomes varied by taxonomy, with the highest and quickest breeding response rates for Charadriiformes (terns, gulls, and auks), primarily with social attraction. Given delayed and variable response times to active restoration, 5 y is appropriate before evaluating outcomes. The database and results serve as a model for tracking and evaluating restoration outcomes, and is applicable to measuring conservation interventions for additional threatened taxa.

The Brown Booby (Sula leucogaster) is a pantropical seabird that exhibits geographic variation. Brewster's Booby (S. l. brewsteri) is the most distinctive form morphologically and genetically. Until recently, Brewster's Booby was restricted to the eastern Pacific Ocean, but it is expanding westward, resulting in increasing sympatry with the Indo-Pacific form, S. l. plotus, and greater potential for interbreeding. We compiled observations of Brewster's Booby outside its usual range and we collected data on pairing patterns in the zone of overlap. At least 65 male and 53 female Brewster's Boobies have been observed on 20 islands in the central and western Pacific, with breeding documented on nine islands, mostly since 2000. Pairing by S. l. brewsteri and S. l. plotus was primarily assortative, with only a few instances of hybridization, all but one of which occurred in locations where no female S. l. brewsteri were present. The morphological differences between S. l. plotus and S. l. brewsteri appear to act as behavioral reproductive isolating mechanisms that restrict interbreeding. The morphological, genetic, and behavioral differences between S. l. brewsteri and other forms of the Brown Booby suggest it would be appropriate under all species concepts to consider Brewster's Booby as a distinct species.

The Oahu Elepaio ( Chasiempis ibidis ) is an endangered forest bird endemic to the Hawaiian island of Oahu. The two most serious threats to the Oahu Elepaio are nest predation by nonnative black rats ( Rattus rattus ) and avian pox ( Avipoxvirus spp.), a disease carried by nonnative mosquitoes. The Oahu Elepaio is conservation reliant because its continued existence depends on rat control. We used 27 years of data from 1995 to 2021 on pox prevalence, nest success, and fecundity with versus without rat control to reexamine the severity of these threats. Prevalence of avian pox declined over time. From 1995 to 2004, pox prevalence averaged 21% ± 4% per year and was positively related to annual rainfall. From 2005 to 2021, pox prevalence was only 2% ± 0.1% and despite several wet years there was no relationship with rainfall. The Oahu Elepaio appears to have evolved resistance to the pox variant currently in Hawaii. Elepaio nest success was higher with rat control (58% ± 1%) than without rat control (42% ± 6%). Nest success did not differ significantly between native tree species (52% ± 6%) and nonnative tree species (58% ± 6%) or between fruiting tree species (58% ± 1%) and nonfruiting species (61% ± 6%). Elepaio annual fecundity was higher with rat control (0.78 ± 0.02) than without rat control (0.48 ± 0.04) and varied among sites and years. The two primary threats to the species have been ameliorated through a combination of effective management and natural adaptation. The species' status should continue to improve if management is maintained, and someday, if patterns of natural adaptation continue, it could break free from conservation reliance.

Newell’s Shearwater (Puffinus auricularis newelli; NESH) and Hawaiian Petrel (Pterodroma sandwichensis; HAPE) are listed under the U.S. Endangered Species Act and have declined by 94% and 78%, respectively, since 1993 due to habitat degradation, predation by introduced predators, collisions with powerlines and light attraction. Given the challenges in protecting nesting birds in their rugged montane habitats, it has long been desirable to create populations of both species in more accessible locations that offer a higher level of protection. We translocated 110 HAPE and 86 NESH chicks over a six-year period from 2015-2020 to a 2.5-ha predator-free enclosure on Kaua`i, Hawai`i. In addition to invasive plant removal and native plant out-planting, we installed 76 artificial burrows to provide nesting sites. Chicks were tube fed 1-20% of their body weight daily in the form of a slurry comprised of squid, fish, salmon oil, and Pedialyte. All NESH and 96% (N=106) of HAPE survived to fledging. Eight HAPE, including three breeding pairs, and one NESH have returned as adults to the translocation site and HAPE have bred at the site, resulting in the first predator-free breeding colony of this species.

Offshore wind energy development (OWED) is rapidly expanding globally and has the potential to contribute significantly to renewable energy portfolios. However, development of infrastructure in the marine environment presents risks to wildlife. Marine birds in particular have life history traits that amplify population impacts from displacement and collision with offshore wind infrastructure. Here, we present a broadly applicable framework to assess and mitigate the impacts of OWED on marine birds. We outline existing techniques to quantify impact via monitoring and modeling (e.g., collision risk models, population viability analysis), and present a robust mitigation framework to avoid, minimize, or compensate for OWED impacts. Our framework addresses impacts within the context of multiple stressors across multiple wind energy developments. We also present technological and methodological approaches that can improve impact estimation and mitigation. We highlight compensatory mitigation as a tool that can be incorporated into regulatory frameworks to mitigate impacts that cannot be avoided or minimized via siting decisions or alterations to OWED infrastructure or operation. Our framework is intended as a globally-relevant approach for assessing and mitigating OWED impacts on marine birds that may be adapted to existing regulatory frameworks in regions with existing or planned OWED.

Abstract: The White Tern (Gygis alba) is a common seabird that nests on islands in tropical and subtropical oceans. In the southeastern Hawaiian Islands, White Terns breed only in urban and suburban areas of Honolulu. The Honolulu population has grown from a single pair in 1961 to 2,300 birds in 2016. We measured breeding success of White Terns in Honolulu and examined aspects of their breeding biology and the environment that may affect breeding. We documented 3,855 breeding events in Honolulu from 2016 to 2019. Breeding success was 68.3% and varied less than 3% among years. Breeding occurred in all months, with lowest activity in the summer and a peak in the winter and spring, but the pattern varied among years. White Terns bred in 64 tree species. Breeding success varied among tree species and was related to characteristics of the trees and their attractiveness to non-native predators. The height of breeding events was 9.26 ± 0.05 m and success was related to height, with higher success in events 5–10 m above ground. The diameter of branches on which breeding occurred was 10.2 ± 0.1 cm and success was related to branch diameter, with lower success on branches >20 cm. The high breeding success of White Terns in Honolulu is related to: the small size and isolation of the O‘ahu population, which may result in reduced intra-specific competition for food; protection from predators provided by the urban environment; and trimming of trees by arborists, which unintentionally improves the value of trees as breeding sites for terns.

An Inca Tern (Larosterna inca) was observed and photographed at several locations in the Hawaiian Islands from 10 March 2021 to 8 January 2022, constituting the northernmost and westernmost record for this species, which breeds on the Pacific coast of South America, and the first for the United States. Here I provide details about the appearance and inter-island movements of this individual, along with evidence indicating that only a single individual was involved in all sightings. The Hawaiian Islands occurrence, along with recent documentation of the Inca Tern in Central America north to Guatemala, points to yet another South American seabird moving north with increasing frequency in the Pacific Ocean.

The U.S. Tropical Pacific (USTP) is a globally important area for seabirds with tens of millions of individuals of 32 species breeding in the region. The two greatest threats to breeding seabirds in the USTP are inundation of colonies caused by global climate change and non-native predators. We assessed the status of seabird species breeding in the USTP and which species would benefit most from restoration activities. We scored each species for nine criteria that reflected their extinction risk and vulnerability to climate change and invasive predators, then summed the scores of all criteria to obtain an overall score and ranked the species in terms of overall conservation need. The top five species at risk (in order) were Hawaiian Petrel (Pterodroma sandwichensis), Newell's Shearwater (Puffinus newelli), Polynesian Storm-Petrel (Nesofregetta fuliginosa), Phoenix Petrel (Pterodroma alba), and Black-footed Albatross (Phoebastria nigripes). We also assessed 86 locations in the USTP as potential source and restoration sites for seabirds to mitigate the impacts of sea level rise and invasive predators. Some restoration actions are underway for three of the top five species in the USTP, but more actions are needed. Two of the top species (Polynesian Storm-petrel and Phoenix Petrel) occur primarily outside the USTP. Actions within the USTP are needed to complement existing conservation measures underway elsewhere in the Pacific and should be prioritized for future management actions.