United States

**Abstract:**

Human disturbance of seabird colonies is increasing globally, activities such as development can have direct negative effects on the breeding grounds. Being flightless, penguins are at higher risk of vehicle collisions in developed areas. Mitigation of these impacts need to be adapted to individual species and situations. Phillip Island, Australia is a successful story of conservation of Little penguins Eudyptula minor. Conservation initiatives are funded by ecotourism to the Penguin Parade®, which attracts over 800,000 paid visitors per year. The carpark built to accommodate around 600 vehicles per night also had Little penguin breeding burrows amongst the parking bays. This unwanted interaction resulted in 21 vehicle collisions with Little penguins within the parking areas between 2012 and 2017. As part of the redevelopment of the visitor centre in 2018, penguins were excluded from the future parking areas to mitigate this risk. While fencing is an effective deterrent to keep Little penguins out, gates across entry/exit roads to allow cars and buses through were not a practical option. Here we investigated the efficacy of modified cattle grids, fauna grids, to restrict the movement of Little penguins. Automated camera-traps were used to observe the animals&#39; behaviour when interacting with the fauna grids. Little penguins approaching the grids were classified into: refusing to cross, unsuccessful crossing attempt, or successful crossing. Initial analysis showed most penguin approaches were unsuccessful crossing attempts, with a smaller proportion refusing to cross, and no successful crossings observed. Our results suggest that fauna grids can be used to effectively restrict the movements of Little penguins and exclude them from unwanted areas. We propose the use of fauna grids as an effective tool to help mitigate road mortality of Little penguins, which may be applicable for other flightless bird species.

**Authors:**

Leanne Renwick¹, Andre Chiaradia¹, Ross Holmberg¹, Damian Prendergast¹

¹Phillip Island Nature Parks

3rd World Seabird Conference

Using fauna grids to prevent penguin mortality

Welcome Seabirders!  

Welcome to Virtual World Seabird Conference 3 - vWSC3! Whether you are in your office or lab, at home, in a coffee shop or bar poaching some wifi, or at a remote field site or research vessel – we are very excited to welcome you to the third ever World Seabird Conference. 

We would like to thank ALL of you for being so patient as WSC3 was scheduled, postponed, rescheduled, revised to virtual, and scheduled again. Throughout all those iterations there was one message that remained perfectly clear – seabirders were eager to meet and share their science. If we could not meet in person then virtual it would have to be, but a 3rd WSC was something everyone wanted. That support and commitment helped the WSU Board of Directors and Member Societies sort through all of the challenges they faced to plan and hold this conference. 

The list of those that need to be thanked is long and, while we plan on recognizing many during the live closing plenary, it is important to do so here in writing as well. 

The Australasian Seabird Group was our Local Host for our plan to meet in Hobart, Tasmania. They invested substantial time and effort to find venues and plan events that we unfortunately were not able to visit. Nonetheless we appreciate their work on behalf of WSC3 and encourage all of you to thank them when you see their members in Gathertown or elsewhere during our virtual meeting. Their willingness to host created the initial excitement for WSC3 and without that our vWSC would not have been possible.

We also wish to thank the Science Program Committee, the Virtual Committee, and the Early Career Scientist Committee for their hard work planning the logistics, events, and schedule for vWSC3. These committees also had to deal with changing parameters and short timelines that made what is always a challenging task even more challenging. The Travel Awards Committee also invested time and effort in developing procedures for awarding travel funds that ultimately would not be implemented. 

Our ability to shift from an in-person to a virtual meeting, and to do so in a way that would be financially feasible, was due to the effective efforts of The International Fundraising Committee and to our financial sponsors. The IFC raised funds to support WSC3 and then, through the good relationships they built with sponsors, ensured we could re-envision how those funds could be used to support a virtual conference that would be affordable and high-quality.

We all owe the WSU Board of Directors and the Representatives of the Member Societies a great deal of thanks. They are the ones who manage the WSU and, for the past 18 months, have had to have a series of challenging meetings and conversations, have had to make a series of difficult choices, have had to do all of that while considering the short- and long-term health of WSU and the World Seabird Conferences, and did this while also managing their own challenges at their day jobs. We are grateful for their diligence, patience, foresight, and throughout all of the meetings, their collegiality. Also – a 6-year term is quite a commitment!

There would not be a WSC3 without a successful WSC1 and WSC2. Thanks go to the Pacific Seabird Group for their support of WSC1 in Victoria, Canada, and to the African Seabird Group for their support of WSC2 in Cape Town, South Africa. In each of these endeavors and for our current conference we were fortunate to work with a dependable and trustworthy partner in Podium Conferences. Michelle Smith and Marischal de Armond have become valued members of our team and have not only helped us plan conferences but have assisted and advised the WSU Chairs and Board on issues above and beyond conference planning. 

As we embark on our vWSC3 week we extend to all of you our thanks for showing up, for being patient, and most importantly for the work you do with seabirds. We are all part of a unique, global community that shares an interest, a fascination, and a passion for birds that make a living in our world’s oceans. We have advanced the science, conservation, and management of seabirds as well the ecosystems they inhabit. We are consistently impressed and motivated by the work you do. 

The WSU formed in 2010 because we saw the need for a global organization to address challenges at a global level. Over the past 11 years WSU has grown, adapted, and evolved to become the community that this week is making vWSC3 a reality. Enjoy the week, appreciate and support the friends and colleagues you have made in the community, and if you see us in a virtual hallway please stop and say hello! 

Thank you for the opportunity to serve all of you and the WSU over the past few years,

Nicholas Carlile, Interim Chair, WSU<br>
Patrick Jodice, 2nd Chair of the WSU<br><br>

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Join us for four days of science, networking and virtual engagement with delegates from around the world!

**Abstract:**

Human disturbance of seabird colonies is increasing globally, activities such as development can have direct negative effects on the breeding grounds. Being flightless, penguins are at higher risk of vehicle collisions in developed areas. Mitigation of these impacts need to be adapted to individual species and situations. Phillip Island, Australia is a successful story of conservation of Little penguins Eudyptula minor. Conservation initiatives are funded by ecotourism to the Penguin Parade®, which attracts over 800,000 paid visitors per year. The carpark built to accommodate around 600 vehicles per night also had Little penguin breeding burrows amongst the parking bays. This unwanted interaction resulted in 21 vehicle collisions with Little penguins within the parking areas between 2012 and 2017. As part of the redevelopment of the visitor centre in 2018, penguins were excluded from the future parking areas to mitigate this risk. While fencing is an effective deterrent to keep Little penguins out, gates across entry/exit roads to allow cars and buses through were not a practical option. Here we investigated the efficacy of modified cattle grids, fauna grids, to restrict the movement of Little penguins. Automated camera-traps were used to observe the animals' behaviour when interacting with the fauna grids. Little penguins approaching the grids were classified into: refusing to cross, unsuccessful crossing attempt, or successful crossing. Initial analysis showed most penguin approaches were unsuccessful crossing attempts, with a smaller proportion refusing to cross, and no successful crossings observed. Our results suggest that fauna grids can be used to effectively restrict the movements of Little penguins and exclude them from unwanted areas. We propose the use of fauna grids as an effective tool to help mitigate road mortality of Little penguins, which may be applicable for other flightless bird species.

**Authors:**

Leanne Renwick¹, Andre Chiaradia¹, Ross Holmberg¹, Damian Prendergast¹

¹Phillip Island Nature Parks

poster

**Abstract:**

The islets of the Tubbataha Reefs Natural Park serve as an important breeding ground for seabirds. This study aimed to determine how the variability in climate has influenced the population dynamics and phenology of six resident breeding seabird species in the park: Red-footed Booby, Brown Booby, Great Crested Tern, Sooty Tern, Brown Noddy and Black Noddy. Survey methods followed Bibby et al. (2002). The data suggests that the increase in sea surface temperature in the area did not negatively influence the inter-annual variability of the seabird population. However, during El Niño events the effects of sea surface temperature changes to Great Crested Tern, Sooty Tern, and Brown Noddy were significant. Chlorophyll a concentration, which was used as a proxy for prey availability, could not be linked to the presence of adult birds, but it reliably predicted the breeding phenology of Great Crested Tern and Sooty Tern in the area. The peak of sea surface temperature was strongly linked to the start of egg-laying for the Great Crested Tern. The future changes in climate could possibly influence these environmental factors and consequently affect the phenology as well as the population of the seabird species in the area. The future occurrence of long and strong El Niño episodes might delay the breeding of these seabirds. The result of this and further studies will help park management better understand seabirds and come up with effective conservation strategies for the species.

**Authors:**

Maria Retchie Pagliawan-Alaba¹, Angelique Songco¹, Arnold van Vliet², Arne Jensen³, Rowell Alarcon¹, Gerlie Gedoria¹

¹Tubbataha Management Office, ²Wageningen University and Research Centre, ³Wild Bird Club of the Philippines

The effects of climate variability on seabirds breeding in the Tubbataha Reefs Natural Park, Philippines

**Abstract:**

Plastic pollution is widely regarded as a major threat to ocean ecosystems. An increasing number of studies show that seabirds frequently ingest plastics, but the drivers of variation in ingestion rates among and within populations and species are not well understood. Vulnerability to plastic pollution will depend on foraging method, diet, and spatial overlap of foraging areas with plastic debris in the oceans. Small pelagic species such as gadfly petrels and storm-petrels, which are among the most threatened groups of seabirds, show higher incidence of plastic ingestion - likely due to their gut anatomy, diet and their propensity to forage in ocean gyres, where surface plastics accumulate. Until recently, relatively little was known about the foraging ecology and at-sea distribution of these species, but with miniaturised tracking devices, we now have more detailed information on their movements. In this study, we use predictive models of plastic debris distributions (based on ocean circulation) along with analyses of the extensive tracking data held in the Seabird Tracking Database to map the spatial overlap (and therefore potential risk) of plastic encounter by small pelagic seabirds. Our analysis highlights the populations, species, seasons and regions for which there is greatest exposure to plastic pollution. Ultimately, our study provides a robust, evidence-based assessment of the problem of plastic pollution for pelagic seabirds, and should lead to increased understanding of the conservation needs of these cryptic, highly threatened species.

**Authors:**

Bethany Clark¹, Ana Carneiro¹, Elizabeth Pearmain¹, Thomas Clay², Richard Phillips³, Andrea Manica⁴, Marie-Morgane Rouyer⁵, Win Cowger⁶, Marcus Eriksen⁷, Carolina Hazin¹, Maria Dias¹

¹BirdLife International, ²University of California Santa Cruz, ³British Antarctic Survey, ⁴University of Cambridge, ⁵CEFE, Univ Montpellier, CNRS, EPHE, IRD, ⁶University of California, Riverside, ⁷Five Gyres Institute

Plastic connectivity: disentangling the problem of plastic pollution for pelagic seabirds

**Abstract:**

Plastic pollution of the World Ocean is widely recognized major and increasing threat to the marine environment, and the seabirds are among the most affected groups of marine biota. Recent studies revealed global distribution of plastic, both macro- and micro-plastics, including most remote areas of the Arctic Ocean. Several recently published papers summarized information on the plastic and seabirds in the Arctic and adjacent areas, and emphasized poor coverage of the topic and lack of the data. Russia is washed by 12 seas and has longest sea shores inhabited by globally important populations of seabirds, but information about plastic pollution in the Russian waters, especially in relation to marine birds and their habitats is virtually absent. Here we present first national overview summarizing information on plastic pollution of the coastal habitats of marine birds and their interaction with plastic debris and microplastic. Our review covers Russian Arctic and seas from the Baltic Sea to and Far East seas. Plastic debris presents in coastal habitats of all studied seas including shores of the most remote high-arctic islands. Data on entanglement or plastic incorporation into the nests of marine birds, collected through interviews and dedicated surveys, are summarized and mapped. The most impacted nesting colonies and affected species are highlighted. All available data on digestion of the plastic particles observed in the Russian seas are compiled. Geographical patterns and possible sources of plastic in seabird habitats are discussed. Possibilities and scopes of further studies and monitoring of the plastic impact on marine birds as well as use of seabirds as fro monitoring of plastic pollution in Russian seas as part of the circumpolar / global monitoring schemes are assessed. The work is partly supported by AMBI / CAFF project Plastics and Seabirds: Habitat mitigation and Russian-Norwegian project MALINOR.

**Authors:**

Maria Gavrilo¹, Ekaterina Tolmacheva², Larisa Zelenskaya³, Yuri Artyukhin⁴, Yulia Bublichenko⁵, Uliana Babiy⁶, Yulia Bogomolova⁷, Alexander Cherenkov⁸, Elena Golubova³, Dmitry Pilipenko⁹, Olga Prokopenko³, Vladimir Semashko¹⁰, Irina Utekhina¹¹, Grigory Tertitskiy¹², Eugene Syroechkovskiy¹³

¹Association Maritime Heritage, ²Kandalaksha State Nature Reserve, ³Institute for Biological Problems of the North RAS, ⁴Pacific Institute for Geography RAS, ⁵Saint-Petersburg Scientific Centre of RAS, ⁶Wrangel State Nature Reserve, ⁷Nenets State Nature Reserve, ⁸Moscow State University, ⁹Commander Islands State Nature Reserve, ¹⁰retired, ¹¹Magadan State Nature Reserve, ¹²Institute for Geography RAS, ¹³BirdsRussia

Seabirds and plastic pollution in the Russian seas - first national review on the problem

**Abstract:**

As bite-sized plastics increasingly invade our oceans, the past decade has seen a rise in studies seeking to understand how plastic ingestion affects the health of wildlife. Seabirds are well represented among plastic-ingesting taxa; with 44% of 409 species currently recorded to ingest plastic, a figure predicted to increase to 99% of species by 2050. Tubenoses (Procellariiformes) are especially well known for plastic-eating behaviour; 63.2% of 144 species are currently known to ingest plastic, with frequencies of up to 100% of individuals in some populations. Though scientists perceive hundreds of health impacts of plastic ingestion on vertebrate animals, few studies find lethal outcomes and research attention has shifted to identifying sub-lethal effects. Sub-lethal health concerns include both physical effects on nutrition, damage to the gut, gut dysbiosis; and chemical or toxicological effects from exposure to plastic-associated (additive and adsorbed) metals and hydrophobic organic chemicals, including toxicity and endocrine disruption. Evidence for statistically significant plastic-associated effects is well-supported, but how many of these effects have demonstrated evidence for health consequences at an organism level or an ecologically relevant scale? Does the ingestion of non-lethal plastic loads cause widespread health consequences for individuals and populations? Is ingestion of plastic no different to ingestion of naturally occurring indigestible items? Or does the evidence lie in a middle ground somewhere between these oft argued extremities. Here we summarise the current state of knowledge of sub-lethal health effects of plastic ingestion in seabirds. We argue that multiple potential pathways between plastic and the measured effect, over-interpretation, exposure concentration and confounding at the root of the disagreement between scientists. We recommend learning from more established fields such as toxicology to establish good practice for reporting on sub-lethal health effects of plastic ingestion in seabirds, with the aim of transparently presenting evidence in a format which disentangles the demonstrated from the perceived.

**Authors:**

Lauren Roman¹, Britta Denise Hardesty¹, Chris Wilcox¹

¹CSIRO

Sub-lethal health effects of plastic ingestion in seabirds: Disentangling the demonstrated from the perceived

**Abstract:**

The North Pacific Pelagic Seabird Database (NPPSD) was created in 2005 by the U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service, with additional support from the North Pacific Marine Research Institute to consolidate available data (~61,000 transects conducted during 1975-2002) on the oceanic distribution of seabirds in the North Pacific generally and Alaska in particular. The NPPSD was expanded greatly in Version 2.0 to include ~290,000 additional transects (1973-2012) conducted in adjacent waters of Russia, Japan, Alaska, Canada and the US West Coast. We have recently expanded the NPPSD by ~30% with the addition of another ~110,000 transects (2013-2019) for a total of 460,285. The NPPSD version 3 includes observations of over 20 million marine birds observed over 47 years. This update provides researchers and resource managers expanded spatial and temporal range for the mapping of marine bird distributions and abundances throughout the North Pacific. Data from the NPPSD has been used to map "hotspots of energy flow," assess species status and trends, and identify Important Bird Areas to assist in conservation planning. As the availability of broad-scale environmental data has increased, the potential to link seabirds to environmental factors will depend on integrated data resources like the NPPSD. Future updates of this USGS database will focus on filling in gaps and developing tools to assist in the linkage between the NPPSD and external data sources.

**Authors:**

Gary Drew¹, John Piatt¹

¹U.S. Geological Survey-Alaska Science Center

The North Pacific Pelagic Seabird Database version 3.0: Expanding spatial-temporal ranges to address broad-scale questions

**Abstract:**

Mechanisms promoting coexistence between closely related species are fundamental for maintaining species diversity. Mechanisms of niche differentiation include allochrony which offsets the peak timing of resource utilisation between species. Many studies focus on both spatial and temporal niche partitioning; however, few have investigated the role allochrony plays in influencing interspecific segregation of foraging distribution and ecology between congeneric species. We investigated the non-breeding migrations of Snares (Eudyptes robustus) and Fiordland penguins (Eudyptes pachyrhynchus), closely related species breeding between 100 - 350 km apart whose migration phenology differs by two months. We examined the degree of overlap given the observed allochrony and a hypothetical scenario where the species commence migration simultaneously. We found that Fiordland penguins migrated to the Sub-Antarctic Frontal Zone and Polar Frontal Zone in the austral autumn whereas Snares penguins disperse westwards staying north of the Sub-Tropical Front in the austral winter. Our results suggest that allochrony is likely to be at the root of segregation because the relative profitability of the different water masses, that the penguins forage in, changes seasonally, which results in the two species utilising different areas over their core non-breeding periods. Furthermore, allochrony reduces relatively higher levels of spatiotemporal overlap during the departure and arrival periods, when the close proximity of the two species' colonies would cause the birds to congregate in similar areas, resulting in high interspecific competition just before the breeding season. Available evidence suggests that the shift in phenology between these species has arisen from adaptive radiation and phenological matching to the seasonality of local resource availability during the breeding season and reduced competitive overlap over the non-breeding season is likely to be an incidental outcome.

**Authors:**

Cara-Paige Green¹, Norman Ratcliffe², David Thompson³, Thomas Mattern⁴, Simon Wotherspoon¹, Mary-Anne Lea¹, Pablo Garcia Borboroglu⁵, Ursula Ellenberg⁶, Kyle Morrison⁷, Klemens Pütz⁸, Paul Sagar⁹, Philip Seddon⁴, Leigh Torres¹⁰, Mark Hindell¹

¹University of Tasmania, ²British Antarctic Survey, ³National Institute for Water and Atmospheric Research, ⁴University of Otago, ⁵New Zealand Penguin Initiative, ⁶La Trobe University, ⁷NA, ⁸Antarctic Research Trust, ⁹National Institute of Water and Atmospheric Research, ¹⁰Oregon State University

The roles of habitat selection and allochrony in niche partitioning in two closely related Eudyptes penguins

**Abstract:**

Seabirds play a vital role in marine ecosystems and the long-term study of their responses to environmental variations can be used to monitor the effects of climate change on marine fauna. However, slight differences in similar seabird species result in a range of responses which complicates our understanding of the effects of environmental changes to marine ecosystems. The present study investigated inter-annual differences in the breeding biology (breeding phenology, chick growth rates and breeding success) and environmental conditions (seasonal sea surface temperatures) of important foraging areas in two sympatric small Procellariiform species, the fairy prion (Pachyptila turtur) and the common diving petrel (Pelecanoides urinatrix), over four reproductive seasons (2017-2020) in Bass Strait, south-eastern Australia. Marine heatwaves occurred during the years of 2018/19 and 2019/20 and coincided with years of delayed laying dates, slower chick growth and reduced breeding success, in both species. While fairy prions maintained a relatively high breeding success and broadly constant breeding phenology, common diving petrels delayed the start of the breeding season by up to 50 days and experienced dramatic collapses in breeding success in years of high marine heat wave occurrence. The difference in physiological capacity and foraging ecology between both species are explored as likely factors contributing to the contrasting breeding seasons observed.

**Authors:**

Yonina Eizenberg¹, Aymeric Fromant¹, John Arnould¹, Arnaud Lechvien¹

¹Deakin University

Contrasting impacts of environmental variability on the breeding biology of two sympatric small procellariiform seabirds in south-eastern Australia

**Abstract:**

Red-throated loons (Gavia stellata) are a species of conservation concern due to the sensitivity of breeding individuals to disturbance and population declines, including a current decline on the Arctic Coastal Plain in northern Alaska, where oil and gas development is slated to increase. Concurrently, populations of two sympatric loon species are either stable or increasing on the Arctic Coastal Plain, highlighting the need to determine drivers of the population decline in red-throated loons. Possible drivers include nearshore marine ecosystem conditions, contaminants or predators. We present recent information on three possible drivers of loon abundance and discuss new research that addresses each of these hypotheses related to red-throated loon population declines in northern Alaska. Unlike sympatric loon species that feed in freshwater, red-throated loons exclusively catch fish in nearshore marine environments to feed themselves and their chicks. Thus, unfavorable shifts in nearshore fish communities may contribute to population decline of red-throated loons if preferred prey species are less abundant or have lower body condition. Ongoing research has revealed long term shifts in fish community composition and catch rates; therefore, identifying red-throated loon prey fish species, their nutritional quality and availability in northern Alaska, and links to loon energetic costs of flight and diving may allow assessment of how marine conditions impact loon breeding success. Contaminants were identified as a concern in northern Alaska over 15 years ago when eggs exhibited elevated levels of toxic polychlorinated biphenyls (PCBs), which may influence loon reproductive success. Determining contemporary contaminant levels, in conjunction with migration information from satellite telemetry data, may provide additional information on contaminant level trends and sources. Predatory Arctic fox (Vulpes lagopus) abundance on the Arctic Coastal Plain is highly variable but years of high fox abundance can negatively affect avian breeding success; therefore, it is important to identify the potential top-down impacts of predators on loon breeding success.

**Authors:**

Brian Uher-Koch¹, Christopher Latty², Angela Matz³, Vanessa von Biela¹, Courtney Amundson¹, Joel Schmutz¹

¹U.S. Geological Survey Alaska Science Center, ²U.S. Fish and Wildlife Service Arctic National Wildlife Refuge, ³U.S. Fish and Wildlife Service Environmental Contaminants Program

Drivers of long-term declines in Red-throated Loon abundance on Alaska?s Arctic Coastal Plain: marine ecosystem conditions, environmental contaminants, or terrestrial predators?

**Abstract:**

Continued warming of the Earth's atmosphere is having a range of ecological, behavioural and physiological impacts on seabirds. The effects of changes in sea surface temperatures on seabirds are well-documented, but the effects of high ambient temperatures on land are not. Like all penguins, moult in Little Penguins is 'catastrophic', with all feathers shed and replaced in ~18 days. As they do not have adequate insulation and waterproofing to forage at sea, they are constrained to land in some of the hottest parts of the year. Long-term survival analysis suggests that adult mortality is greatest in years when high ambient temperatures are paired with low humidity during moult. Given current climate projections, successful management of Little Penguins requires a better understanding of the physiological processes and habitat features that influence mortality events. In this study we aimed to identify which birds are most at risk of heat stress during moult, and why. Using a novel approach to field respirometry, we investigated thermoregulatory costs of moulting birds in response to ambient temperature and humidity. Our results predicted that penguins in early stages of moult would be most affected by heat exposure, as they displayed a significant increase in metabolic rate at higher temperatures compared to mid and late moult birds. During a heat wave in 2019, the greatest mortality event of moulting adult Little Penguins on record occurred at Phillip Island in south-Eastern Australia. As predicted, all recorded deaths were birds in early stages of moult. We are currently quantifying the microclimates of burrows and vegetation types and investigating how birds are using structural habitat during extreme weather events. Results will help determine how Little Penguins are currently coping with extreme temperatures on land, and identify adaptation options most likely to reduce negative climate change impacts for the species across their distribution.

**Authors:**

Lauren Tworkowski¹, Peter Dann², Ursula Ellenberg¹, Kylie Robert¹

¹La Trobe University, ²Phillip Island Nature Parks

Impacts of terrestrial heat waves on survival of little penguins during moult

**Abstract:**

Seabirds on islands in the California Current are often heralded as indicators of ocean climate variability. However, far less is known about the responses of seabirds at time scales of hundreds to thousands of years. Near the southern end of the California Current in the Channel Islands National Park, two small nocturnal alcids breed on Santa Barbara Island. This includes the zooplanktivorous Cassin's Auklet (Ptychoramphus aleuticus) as well as the more generalist Scripps's Murrelet (Synthliboramphus scrippsi). Adults of both seabirds are consumed by Barn Owls (Tyto alba), and one particular owl roost in a sea cave contains a record of accumulated prey bones spanning at least the last ~1500 years. As part of a larger ongoing project detailing the faunal remains from the cave, we compared the isotopic niche dynamics for auklets and murrelets over the last millennium. We used stratigraphy and AMS 14C dated samples to determine ages of the seabird bones and extracted bone collagen for stable isotope analysis (𝛿13C and 𝛿15N). We also compiled data on marine paleoclimate to determine how changing conditions may have affected niche dynamics and partitioning between the two alcids. We also evaluated the impacts of more recent historical changes to the island such as the introduction of non-native plants and animals and the advent of commercial fisheries. Finally, we discuss these findings in the context of ongoing climate change and implications for the future.

**Authors:**

Sarah Thomsen¹, Paul Collins², René L. Vellanoweth Vellanoweth³, Amira Ainis⁴, Jessica Rodriguez³, Santos Ceniceros³, Tara Smiley⁵, Jen Cotton⁶, Rebecca Terry¹

¹Oregon State University, ²Santa Barbara Museum of Natural History, ³California State University, Los Angeles, ⁴University of Oregon, Eugene, ⁵Indiana University, ⁶California State University Northridge

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