Hawaii Wildlife Ecology Lab

Permanent URI for this collection

https://hdl.handle.net/10125/66566

Browse

Now showing 1 - 10 of 43

Human-Wildlife Interactions of Hawaiian Waterbirds in Managed Wetlands
(2025-05-15) Koa Grabar; Melissa R. Price; Kawika B. Winter
At-risk Hawaiian waterbirds utilize a variety of wetland habitats, including lo‘i kalo (Indigenous wetland agro-ecosystems used to grow Colocasia esculenta, a staple Hawaiian crop); however, how these systems support species recovery remains understudied. This represents a significant knowledge gap, as the expansion of Hawaiian agro-ecosystems has the potential to provide numerous ecosystem services that benefit both local and Indigenous communities, as well as the environment, while simultaneously supporting the recovery endangered waterbirds in the face of threats such as sea level rise. These benefits include local food production and, in turn, improved food security, cultural (re)connection, and the creation of habitat for endemic and endangered wildlife. Despite these benefits, the management actions necessary to maintain a lo‘i may be perceived as disruptive or harmful to the waterbird species inhabiting them. Actions such as the clearing of vegetation, fluctuations in water levels, and presence during nesting periods, could impact nesting success, so policies that restrict these actions during the nesting season are sometimes imposed on farmers. This study aims to lay a foundation for better understanding the relationships between stewards and the Aeʻo (Hawaiian Stilt, Himantopus mexicanus knudseni), ʻAlae ʻula (Hawaiian Gallinule, Gallinula galeata sandvicensis), ʻAlae keʻokeʻo (Hawaiian Coot, Fulica alai) and pure/hybrid Koloa maoli (Hawaiian duck, Anas wyvilliana). To address this question, I will conduct surveys, inquiring about management and the steward’s thoughts regarding waterbirds at their site, and measure the alert response and flight-initiation distances of waterbirds within their respective wetlands when approached by stewards. To further elucidate these interactions, I will replicate this study at multiple types of sites where waterbirds interact with land stewards, such as state and county parks, and government-managed wetlands. I expect to find that steward perceptions and desired level of interactions, frequency of caretaking, and waterbird species type will be correlated with alert and flight initiation distances when birds are approached by stewards, compared to non- stewards. The findings of this study will help to elucidate the responses of different waterbird species and underscore the contributions of managed wetlands to waterbird recovery.
Characterization of the birdscape of a collaboratively managed Indigenous and Community Conserved Area in Hawai‘i: What is the potential for increasing native bird biodiversity?
(2025-05-07) Eryn Opie
Indigenous resource management practices increase habitat heterogeneity, and thus may contribute to species biodiversity while simultaneously achieving other social-ecological goals such as food production, but few if any studies to date have evaluated effects on avian biodiversity. Small patches of restored habitat may be of particular importance on islands where species historically had smaller ranges due to land area constraints. Due to factors introduced in the last few centuries, in the Hawaiian Islands lowland habitats are largely devoid of native passerines due to disease, mammalian predators, and habitat loss. In addition, native seabirds, waterbirds, and shorebirds occur in relatively small patches of suitable habitat due to impacts from invasive predators and the historical clearing of native vegetation for plantation agriculture and urban development. Given the lack of native birds in heavily human-modified areas of the Hawaiian Islands, there is a need to assess the occurrence of native birds in these landscapes, and the potential for improving native bird biodiversity with Indigenous Resource Management (IRM) practices. We utilized monthly point counts over two years to characterize the avian communities at sites within the He‘eia National Estuarine Research Reserve on the island of O‘ahu, Hawai‘i, where stewards engage in restoration of biocultural conservation practices and relationships. Our study found a higher abundance of native and endangered waterbirds and shorebirds in areas where biocultural restoration had been initiated, and few if any native birds in unrestored areas. Very few native seabirds and no native forest birds were detected indicating that additional targeted actions such as disease control, removal of invasive predators, and restoration of preferred habitat may be necessary to enable recolonization by these. Our results are consistent with other studies suggesting that even small patches of heterogenous landscapes managed under IRM practices are important contributions toward improving native bird biodiversity.
Prey selection in precocial chicks of the Endangered Hawaiian Stilt (ae‘o - Himantopus mexicanus knudseni)
(2020-09-30) Melissa R. Price; Andreanna Cole; Kristen Harmon; Clarine Phipps
Recovery of endangered species is dependent upon maximizing reproductive success and 1 minimizing mortality, but management actions aimed at increasing recruitment are often 2 hindered by a lack of knowledge at critical life history stages. For example, the dietary 3 preferences of precocial chicks may differ from nesting adults; thus, the optimal foraging habitat 4 may also differ between these life stages. The Endangered Hawaiian Stilt (ae‘o - Himantopus 5 mexicanus knudseni), a subspecies of the Black-necked Stilt, is considered a generalist forager, 6 but little is known regarding prey selection in precocial chicks. In this study, stable isotope 7 mixing models were used to estimate the contribution of potential prey sources to stilt chick diets 8 in wetlands on O‘ahu Island, Hawai‘i. We found predicted contributions to be similar among 9 potential prey items at a site with high prey diversity and the oldest and largest chicks. At three 10 other sites, younger chicks appeared to select particular items from among available prey, 11 including species in the orders Hemiptera (true bugs) and Araneae (spiders). Species in these 12 orders were lower in biomass compared to other species available at each site, suggesting the 13 chicks were selecting for these items from among available prey items, similar to other related 14 species. Our results suggest that Hawaiian Stilt chicks may preferentially select certain prey 15 items which are easy to handle and high in nutrients important to development, and likely 16 diversify their diet as they gain dexterity and height. The results from this study may inform 17 decisions for optimal habitat and macroinvertebrate management in Hawaiian Stilt nesting sites 18 to maximize reproductive success and survival.
Environmental drivers of seasonal shifts in abundance of wild pigs (Sus scrofa) in a tropical island environment
(2022-09-05) Derek R. Risch; Shaya Honarvar; Melissa R. Price; Derek R. Risch
Background: Non-native wild pigs (Sus scrofa) threaten sensitive flora and fauna, cost billions of dollars in economic damage, and pose a significant human–wildlife conflict risk. Despite growing interest in wild pig research, basic life history information is often lacking throughout their introduced range and particularly in tropical environments. Similar to other large terrestrial mammals, pigs possess the ability to shift their range based on local climatic conditions or resource availability, further complicating management decisions. The objectives of this study were to (i) model the distribution and abundance of wild pigs across two seasons within a single calendar year; (ii) determine the most important environmental variables driving changes in pig distribution and abundance; and (iii) highlight key differences between seasonal models and their potential management implications. These study objectives were achieved using zero-inflated models constructed from abundance data obtained from extensive field surveys and remotely sensed environmental variables. Results: Our models demonstrate a considerable change in distribution and abundance of wild pigs throughout a single calendar year. Rainfall and vegetation height were among the most influential variables for pig distribution during the spring, and distance to adjacent forest and vegetation density were among the most significant for the fall. Further, our seasonal models show that areas of high conservation value may be more vulnerable to threats from wild pigs at certain times throughout the year, which was not captured by more traditional modeling approaches using aggregated data. Conclusions: Our results suggest that (i) wild pigs can considerably shift their range throughout the calendar year, even in tropical environments; (ii) pigs prefer dense forested areas in the presence of either hunting pressure or an abundance of frugivorous plants, but may shift to adjacent areas in the absence of either of these conditions; and (iii) seasonal models provide valuable biological information that would otherwise be missed by common modeling approaches that use aggregated data over many years. These findings highlight the importance of considering biologically relevant time scales that provide key information to better inform management strategies, particularly for species whose ranges incl
A comparison of abundance and distribution model outputs using camera traps and sign surveys for feral pigs
(2020-10-14) Derek R. Risch; Jeremy Ringma; Shaya Honarvar; Melissa R. Price; Derek Risch
Species distribution models play a central role in informing wildlife management. For models to be useful, they must be based on data that best represent the presence or abundance of the species. Data used as inputs in the development of these models can be obtained through numerous methods, each subject to different biases and limitations but, to date, few studies have examined whether these biases result in different predictive spatial models, potentially influencing conservation decisions. In this study, we compare distribution model predictions of feral pig (Sus scrofa) relative abundance using the two most common monitoring methods: detections from camera traps and visual surveys of pig sign. These data were collected during the same period using standardised methods at survey sites generated using a random stratified sampling design. We found that although site-level observed sign data were only loosely correlated with observed camera detections (R2 ¼ 0.32–0.45), predicted sign and camera counts from zero-inflated models were well correlated (R2 ¼ 0.78–0.88). In this study we show one example in which fitting two different forms of abundance data using environmental covariates explains most of the variance between datasets. We conclude that, as long as outputs are produced through appropriate modelling techniques, these two common methods of obtaining abundance data may be used interchangeably to produce comparable distribution maps for decision-making purposes. However, for monitoring purposes, sign and camera trap data may not be used interchangeably at the site level.
Population size, distribution and habitat use of the Hawaiian Short-eared Owl (Asio flammeus sandwichensis) on O'ahu
(2018-01-31) Melissa R. Price; Javier Cotin
The 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.
Breeding phenology and daily activity of the Hawaiian Short-eared Owl (Asio flammeus sandwichensis) on O'ahu
(2018-01-31) Kyle E. Davis; Afsheen A. Siddiqi; Melissa R. Price; Javier Cotin
Breeding Ecology of Hawaiian Short-eared Owls (Asio flammeus sandwichensis)
(2023-06-30) Melissa R Price; Olivia Wang
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.
INDIGENOUS KNOWLEDGE AND FACTORS INFLUENCING DETECTABILITY OF PUEO (HAWAIIAN SHORT-EARED OWL, ASIO FLAMMEUS SANDWICHENSIS)
(2023-05-16) Kaleiheana-a-Pōhaku Stormcrow; Melissa R. Price; Kawika B. Winter; Noelani Puniwai
Apex predators such as raptors play important roles in ecosystem regulation. In addition to these important roles and the charismatic nature of apex predators, apex predators often have a mirrored cultural significance for Indigenous Peoples. When their symbolic and spiritual value is so great that it affects that culture’s relationship and adaptation to the environment, they are considered Cultural Keystone Species (CKS). In addition to supporting ecosystem complexity, these species support cultural complexity regarding social identity, cultural practices, and beliefs. Pueo are the only remaining native raptor that breed across the Hawaiian archipelago, and as such play key ecological and cultural roles. In this thesis research I aimed to: (1) highlight the breadth of Indigenous Knowledge of Pueo documented in Hawaiian language newspapers and (2) identify factors influencing Pueo detectability on Hawaiʻi Island. Pueo have relationships with multiple akua (elemental forces) who play vital roles in ecosystem functionality and nutrient cycling, and have relationships with 35 species across articles, indicating our kūpuna (ancestors) understood the system stability that Pueo supported, and the functionality of the pilina (relationship) that Kānaka (Native Hawaiians) have with Pueo. Results from field surveys demonstrate that Pueo utilize every available terrestrial habitat type in Hawaiʻi, but their occupancy and detection probability are constrained by elevation and temperature respectively. On Hawaiʻi island, where Pueo co-occur with ʻIo (Buteo solitarius), we observed a potential temporal shift in their behavior. Together, the results of these chapters support the notion that Pueo are a Cultural Keystone Species and a generalist apex predator with critical cultural and ecological functions.
2022 O‘ahu ʻUaʻu kani Long-term Monitoring Project
(2023-01-04) Melissa Price; Jessica Idle

Browse

Recent Submissions