Behavioral Ecology, Taxonomy, and Conservation Genetics of the Bahama Oriole (Icterus northropi)

In this dissertation, I examined the Bahama Oriole (Icterus northropi) at multiple scales, with the aim of developing a sound management plan for this critically endangered bird. In the first of five studies, I measured plumage variation among four allopatric populations of the former Icterus dominicensis complex in the Caribbean. Diagnosable plumage differences among populations contributed to the subsequent elevation of each of these populations (including northropi) to species status. In the second study, I examined molecular variation in subpopulations of 1. northropi on North Andros, Mangrove Cay, and South Andros, The Bahamas. I identified several patterns of genetic variation that will inform conservation planning. The third study explored the population status and breeding ecology of the Bahama Oriole. My estimates of 141- 254 individuals remaining globally contributed to an IUCN Red List designation as critically endangered. Orioles selected nesting trees that were significantly taller, less likely to have shrubs underneath, farther from cover, and with more palm trees nearby than randomly available palm trees. Lethal yellowing disease devastated coconut palms regionally on North Andros during the course of our study, but palms on South Andros and Mangrove Cay, where oriole density was higher, remained healthy. In the fourth study, I assessed the Bahama Oriole\u27s community-level relationships, including the relative densities of other avian species in three habitats (pine forest, coppice, and anthropogenic habitat), foraging strategies, and inter- and intraspecific social interactions. My findings indicate coppice is vitally important to resident, migrating, and wintering birds. Collectively, these studies identify key conservation priorities to save this critically endangered bird. In my final study, a literature review, I explored the ecological consequences of extinction in a well-studied insular model: the Hawaiian Islands avifauna. Five of six islands have significantly different trophic guild structure now than they did prior to the arrival of humans, due to a combination of extinction events and introduced bird species. Very few extinct bird species have been replaced by equivalent ecological substitutes in the present day avifauna, leading to coextinctions of dependent species. This research highlights the importance of preventing extinctions in the remaining global avifauna

Breeding Ecology of Hawaiian Short-eared Owls (Asio flammeus sandwichensis)

Short-eared Owls (Asio flammeus) are an appropriate study species for understanding intraspecific variations in life-history traits in raptors due to their global distribution across continental and island systems at a variety of latitudes. In Hawai‘i, little is known about the ecology of Pueo (Hawaiian Short-eared Owls, A. f. sandwichensis), but populations are thought to be in decline and are state-listed as endangered on O‘ahu. While studies of other Short-eared Owl subspecies serve as a starting point for creating conservation plans for Pueo, initial research has indicated differences in diet, habitat use, and movement ecology of Pueo versus continental Short-eared Owls. Given these differences, further regional studies from Hawai‘i are necessary to ensure management actions adequately address the needs of Pueo. In Chapter 2 of this study, I investigated the breeding ecology of Pueo using a collaborative approach to combine results from targeted nest-searching at two focal study sites on O‘ahu with incidental reports of Pueo nests across the Hawaiian Islands. In Chapter 3 I used these results to draft management recommendations to minimize disturbance to breeding Pueo. At our focal study sites, I found that Pueo select sites with greater vegetation height and density than the surrounding environment for nesting, but that these same vegetation characteristics do not necessarily correlate to increased nest survival. The diet of breeding Pueo was relatively diverse and contained more bird prey when compared to that of North American and European Short-eared Owls. However, diet did not differ significantly among breeding Pueo pairs. Across both focal study sites and incidental observations, Pueo nest initiation spanned November through July, with a peak in February and March. Pueo breeding habitat ranged from non-native dry grasslands at low-elevation to high-elevation native wet forest, showing a marked increase in breeding habitat diversity compared to North American and European Short-eared Owls. Our results establish a basis for informing Pueo conservation in Hawai‘i, including recommendations towards reducing different types of nest disturbance and data to inform spatial and temporal nest buffers. State-wide management actions must account for the expanded breeding season and diversity of breeding habitat types of Pueo

Habitat Use of Hawaiian Waterbirds in Kawainui Marsh

In Kawainui Marsh, located on the windward side of O‘ahu, eleven man-made ponds were developed by the U.S. Army Corps of Engineers and the Hawai‘i Department of Forestry and Wildlife (DOFAW) to supplement nesting and foraging habitat for endangered, native Hawaiian waterbirds ( ae'o - Hawaiian stilt (Himantopus mexicanus knudseni), ʻalae keokeo - Hawaiian coot (Fulica alai), and 'alae 'ula - Hawaiian gallinule (Gallinula galeata sandvicensis). Management of hydrological conditions is thus a priority for DOFAW, as robust water circulation is critical to provide optimal wetland habitat for native waterbirds, as well as to prevent outbreaks of avian botulism caused by natural toxins produced in wetland soils. A better understanding of Hawaiian waterbird use of managed wetland habitat in relation to water quality is needed to implement effective management strategies. The objectives of this project are to: (1) compare water quality parameters among ponds within the Kawainui Marsh pond system; (2) determine the relationship between water depth and water quality; (3) evaluate habitat use of Hawaiian waterbirds in relation to water depth and water quality. Weekly surveys were conducted in the wetland pond system from May 2018 through March 2019, between the hours of 8:00 AM and 11:00 AM, to measure water quality parameters (temperature, dissolved oxygen [DO], pH, salinity, turbidity, and oxidation-reduction potential [ORP]) using a YSI ProDSS sonde. A census of the number of Hawaiian waterbirds and their behaviors was recorded in the pond system concurrently during water quality surveys. Data was divided into wet and dry seasons, which correlated with precipitation. Two-way analysis of variance (ANOVA) tests were used to compare water quality parameters and presence of waterbirds between season and among ponds, as well as test for an interaction between season and pond. Regression models were used to determine the relationships between water depth and (1) water quality parameters, and (2) waterbird behaviors. Hawaiian coots were observed most frequently during the wet season, when water depths were greatest, and primarily utilized the North Ponds, which had the greatest number of ponds with water throughout both wet and dry seasons. Hawaiian coots showed a preference for ponds with deeper water, particularly when foraging; however, no observations of nesting Hawaiian coots, and very few observations of resting Hawaiian coots, were recorded during this study period. Maintaining water depths above one foot may increase the number of foraging Hawaiian coots during the dry season. Hawaiian stilts were frequently observed in both the wet and dry seasons; however, Hawaiian stilts were observed nesting only during the dry season, which is likely because the dry season coincides with the Hawaiian stilt nesting season. Hawaiian stilts utilized the North and South Ponds for foraging, but primarily utilized the North Ponds for nesting, resting, and preening. The greatest number of nesting stilts were observed in pond 11, which may be due to the number of small islands that provided preferred nesting habitat. Hawaiian stilts do not seem to be limited by water depth, particularly when foraging; however, additional data on nest-site characteristics is needed to inform management decisions for Hawaiian stilt habitat. Hawaiian gallinules were not frequently observed during this study period, but when observed, gallinules primarily utilized the North Ponds for foraging in both wet and dry seasons. One Hawaiian gallinule was observed nesting in pond 4 during the dry season, which could be due to the availability of dense vegetation throughout that pond. Hawaiian gallinules may prefer ponds with deeper water, as they were most frequently found foraging in ponds with water depths of one to two feet. Overall, our results suggest maintaining water depths in Kawainui Marsh is most important for providing foraging habitat for Hawaiian coots and nesting habitat for Hawaiian stilts; however, more data collection is needed to determine specific water depths.Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlif

HAWAIIAN BAND-RUMPED STORM PETREL PROJECT

The Hawaiian Band-rumped Storm Petrel (Oceanodroma castro), listed under the Endangered Species Act in 2016, is finally receiving much-needed protection, but little is known about its genetic diversity in the Hawaiian islands. Once widespread, the range of this species is now restricted to small pockets on high elevation steep surfaces that may be better protected from predator threat and light pollution. Due to their low population numbers and remote locations, only one active nesting area, on Hawai'i island, has been confirmed, despite other evidence suggesting they are indeed nesting on multiple Hawaiian islands. With only a few hundred individuals remaining, the Hawaiian populations may have problems normally associated with small numbers, including demographic stochasticity and inbreeding. The efforts carried out with this permit are aimed at conserving these remnants of a once flourishing Hawaiian species. These efforts include studying nesting behavior to determine nest-site preferences and modern DNA-genetic analyses to determine the inbreeding status, interisland connectivity, and the potential for establishment of novel colonies. These studies are labor-intensive and require expenditures of funds for supplies, equipment for molecular genetics and reagents. This report details the objectives achieved during the final year of this project.U.S. Fish and Wildlife Servic

Diverse habitat use during two life stages of the critically endangered Bahama Oriole (Icterus northropi): community structure, foraging, and social interactions

Our ability to prevent extinction in declining populations often depends on effective management of habitats that are disturbed through wildfire, logging, agriculture, or development. In these disturbed landscapes, the juxtaposition of multiple habitat types can be especially important to fledglings and young birds, which may leave breeding grounds in human-altered habitat for different habitats nearby that provide increased foraging opportunities, reduced competition, and higher protection from predators. In this study, we evaluated the importance of three habitat types to two life stages of the critically endangered Bahama Oriole (Icterus northropi), a synanthropic songbird endemic to Andros, The Bahamas. First, we determined the avian species composition and relative abundance of I. northropi among three major vegetation types on Andros: Caribbean pine (Pinus caribaea) forest, coppice (broadleaf dry forest), and anthropogenic areas, dominated by nonnative vegetation (farmland and developed land). We then compared the foraging strategies and social interactions of two age classes of adult Bahama Orioles in relation to differential habitat use. Bird surveys late in the Bahama Oriole's breeding season indicated the number of avian species and Bahama Oriole density were highest in coppice. Some bird species occurring in the coppice and pine forest were never observed in agricultural or residential areas, and may be at risk if human disturbance of pine forest and coppice increases, as is occurring at a rapid pace on Andros. During the breeding season, second-year (SY) adult Bahama Orioles foraged in all vegetation types, whereas after-second-year (ASY) adults were observed foraging only in anthropogenic areas, where the species nested largely in introduced coconut palms (Cocos nucifera). Additionally, SY adults foraging in anthropogenic areas were often observed with an ASY adult, suggesting divergent habitat use for younger, unpaired birds. Other aspects of foraging (vegetation features, food-gleaning behavior, and food items) were similar for the two age classes. Older Bahama Orioles exhibited relatively higher rates of social interactions (intraspecific and interspecific pooled) in anthropogenic areas, and won more interaction outcomes compared to younger adults. Our findings concur with those of other studies indicating dry broadleaf forest is vitally important to migrating, wintering, and resident birds, including the critically endangered Bahama Oriole, which appears to depend heavily on this vegetation type during certain life stages

Population size, distribution and habitat use of the Hawaiian Short-eared Owl (Asio flammeus sandwichensis) on O'ahu

Technical report prepared for the State of Hawaiʻi Department of Land & Natural Resources on population size, distribution and habitat use of the Hawaiian Short-eared Owl (Asio flammeus sandwichensis) on O'ahuThe Pueo (Asio flammeus sandwichensis), once common across the Hawaiian Islands, is currently state-listed as Endangered on O'ahu. The Pueo provides important ecosystem services by controlling population sizes of introduced rodents and preying on other introduced and native species, including birds and invertebrates. As the only native raptor that breeds on the main Hawaiian Islands, the Pueo plays an important role in top-down ecological regulation and is also valued by native Hawaiians and other Hawai'i residents. Although the Pueo has been recorded in a variety of vegetation types in the Hawaiian archipelago, key habitat selection variables are still unknown. In this study, we optimized a survey methodology to improve population estimates and define vegetation types important to population stability and we compared distribution among vegetation types and overall population densities of Pueo with other Short-eared Owl populations across the globe. Three different approaches were used: (a) standardized surveys by trained personnel; (b) citizen science reports of Pueo sightings submitted to an online portal www.pueoproject.com; and (c) citizen science reports to eBird www.ebird.org, a publicly available, well-established, and curated international online portal for submitting bird sighting reports. We collected more than 50 Pueo sightings in one year through the Pueo project online portal, while the eBird portal collected 43 reports in three decades. Information gathered through the citizen science portal was highly valuable for obtaining phenology and breeding event observations (nests, owlet locations, display flights), however, data collected in this manner were biased due to the lack of standard distribution of the observers, which hampered their usefulness for running distribution models or other population analyses. During the standardized surveys Pueo were observed on agricultural lands, wetlands, short grasslands and open native vegetation. Pueo were detected, on average, 23 minutes before twilight. Estimated densities ranged from 0 to 3.3 Pueo per 100 ha across vegetation types, with most detections occurring in open vegetation types, such as agricultural lands, grasslands, and wetlands. Based on observed densities, the population of Pueo inhabiting O'ahu was estimated at 807 individuals, with 95% confidence intervals of 8 to 2199. Densities obtained from standardized, randomized surveys are aligned with those studies targeting known Short-eared Owl populations with a high rate of occupancy, which does not seem to be the situation on O'ahu, especially if we consider the high level of threats that this species faces in Hawai'i and the observations of declining populations that local inhabitants have reported in person or submitted to the Pueo Project portal. Densities on O'ahu are probably similar to the ones reported in non-targeted, randomized and standardized studies, where owls occupy territories with high prey availability, but leave unoccupied low-prey-density territories. Based on this information, we consider the most likely population number to be on the lower end of the estimated range of possibilities

Population genetics and the effects of a severe bottleneck in an ex situ population of critically endangered Hawaiian tree snails

As wild populations decline, ex situ propagation provides a potential bank of genetic diversity and a hedge against extinction. These programs are unlikely to succeed if captive populations do not recover from the severe bottleneck imposed when they are founded with a limited number of individuals from remnant populations. In small captive populations allelic richness may be lost due to genetic drift, leading to a decline in fitness. Wild populations of the Hawaiian tree snail Achatinella lila,a hermaphroditic snail with a long life history, have declined precipitously due to introduced predators and other human impacts. A captive population initially thrived after its founding with seven snails, exceeding 600 captive individuals in 2009, but drastically declined in the last five years. Measures of fitness were examined from 2,018 captive snails that died between 1998 and 2012, and compared with genotypic data for six microsatellite loci from a subset of these deceased snails (N5335), as well as live captive snails (N5198) and wild snails (N592). Surprisingly, the inbreeding coefficient (Fis) declined over time in the captive population, and is now approaching values observed in the 2013 wild population, despite a significant decrease in allelic richness. However, adult annual survival and fecundity significantly declined in the second generation. These measures of fitness were positively correlated with heterozygosity. Snails with higher measures of heterozygosity had more offspring, and third generation offspring with higher measures of heterozygosity were more likely to reach maturity. These results highlight the importance of maintaining genetic diversity in captive populations, particularly those initiated with a small number of individuals from wild remnant populations. Genetic rescue may allow for an increase in genetic diversity in the captive population, as measures of heterozygosity and rarified allelic richness were higher in wild tree snails