United States

**Abstract:**

The Northern Humboldt Current System is highly productive, but unpredictable. Endemic seabirds in this region evolved under changing conditions by exhibiting flexible breeding and feeding strategies. In this study, we tested how the foraging behavior of guanay cormorants (Phalacrocorax bougainvillii) in Punta San Juan, Peru, changes under four indices of availability of anchovy or &quot;quality&quot; of the year. In 2019, a deeper 15 °C isotherm, warmer waters and a low body condition of the birds were observed. In 2017 the birds had a better body condition than in 2019 and 2020, presenting colder waters and an intermediate depth of the isotherm of 15 °C between 2019 and 2020. For this reason, 2017, 2019 and 2020 were characterized as years &quot;good&quot;, &quot;poor&quot; and &quot;intermediate&quot;, respectively. GPS-TDR loggers were placed on forty, forty and fifty chick rearing birds in 2017 (good), 2019 (poor) and 2020 (intermediate), respectively. In poor and intermediate years, the Guanayes made significantly longer trips, duration and distance from the colony than in good years (total distance traveled = 75.9 and 82.3 vs 47.7 km, trip duration = 3.7 and 3.9 vs 2.8 h, ranging range = 24.1 and 27.1 vs 16.5 km). Also in poor and intermediate years, the Guanayes did significantly higher number of diving bouts and number of dives per trip than in good years (N° diving bouts/trip = 2.45 and 2.05 vs. 1.7, N° dives/trip = 117.13 and 127.1 vs. 72.12). Greater foraging areas were also recorded in poor and intermediate years than in good years (2,092 and 2,488 vs. 1,133 km2). However, the Guanayes dived deeper and longer in good and poor years compared to intermediate years (Maximum dive depth = 12.4 and 11.4 vs. 8 m, Dive duration = 29.2 and 26.6 vs. 21 s). This study shows that under different environmental conditions the feeding behavior of the guanay cormorant is flexible, making more effort to find its food in warm conditions. Higher foraging effort is likely related to deeper and more dispersed schools of anchovy.

**Authors:**

Diego Gonzales-DelCarpio¹, Carlos Zavalaga¹, Rosana Paredes², Lyanne Ampuero-Merino³

¹Unidad de Investigación de Ecosistemas Marinos - Grupo Aves Marinas, ²Department Fisheries and Wildlife - Oregon State University, ³Programa Punta San Juan

3rd World Seabird Conference

Flexibility of Guanay Cormorant foraging behavior under an unpredictable marine environment

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:**

The Northern Humboldt Current System is highly productive, but unpredictable. Endemic seabirds in this region evolved under changing conditions by exhibiting flexible breeding and feeding strategies. In this study, we tested how the foraging behavior of guanay cormorants (Phalacrocorax bougainvillii) in Punta San Juan, Peru, changes under four indices of availability of anchovy or "quality" of the year. In 2019, a deeper 15 °C isotherm, warmer waters and a low body condition of the birds were observed. In 2017 the birds had a better body condition than in 2019 and 2020, presenting colder waters and an intermediate depth of the isotherm of 15 °C between 2019 and 2020. For this reason, 2017, 2019 and 2020 were characterized as years "good", "poor" and "intermediate", respectively. GPS-TDR loggers were placed on forty, forty and fifty chick rearing birds in 2017 (good), 2019 (poor) and 2020 (intermediate), respectively. In poor and intermediate years, the Guanayes made significantly longer trips, duration and distance from the colony than in good years (total distance traveled = 75.9 and 82.3 vs 47.7 km, trip duration = 3.7 and 3.9 vs 2.8 h, ranging range = 24.1 and 27.1 vs 16.5 km). Also in poor and intermediate years, the Guanayes did significantly higher number of diving bouts and number of dives per trip than in good years (N° diving bouts/trip = 2.45 and 2.05 vs. 1.7, N° dives/trip = 117.13 and 127.1 vs. 72.12). Greater foraging areas were also recorded in poor and intermediate years than in good years (2,092 and 2,488 vs. 1,133 km2). However, the Guanayes dived deeper and longer in good and poor years compared to intermediate years (Maximum dive depth = 12.4 and 11.4 vs. 8 m, Dive duration = 29.2 and 26.6 vs. 21 s). This study shows that under different environmental conditions the feeding behavior of the guanay cormorant is flexible, making more effort to find its food in warm conditions. Higher foraging effort is likely related to deeper and more dispersed schools of anchovy.

**Authors:**

Diego Gonzales-DelCarpio¹, Carlos Zavalaga¹, Rosana Paredes², Lyanne Ampuero-Merino³

¹Unidad de Investigación de Ecosistemas Marinos - Grupo Aves Marinas, ²Department Fisheries and Wildlife - Oregon State University, ³Programa Punta San Juan

technical paper

**Abstract:**

Marine heatwaves are increasing in frequency and can disrupt marine ecosystems non-linearly. In this study we examined the effect of the North Pacific warming event of 2014, the largest long-term sea surface anomaly on record, on black-legged kittiwake (Rissa tridactyla) foraging trips before, during, and after the event. We assessed foraging trip characteristics (trip distance and duration), the dispersal of foraging locations, and the persistence of foraging areas within and among years. Foraging trip characteristics, foraging area size, and location varied from year to year. Kittiwakes foraging was more dispersed, direct, and farther from the colony in years immediately after and during the warming event. A third of the foraging area used pre-heat wave (2012) was important in subsequent years, which indicates that this area was, and may still be, a perennial foraging hot spot. During the chick-rearing stage black-legged kittiwakes increased their speed and reduced the proportion of resting compared to the incubation stage. We conclude that marine heat waves may have a strong impact on seabird foraging, extending foraging ranges, and that those impacts may be nonlinear with a strong lag.

**Authors:**

Orla Osborne¹, Patrick O'Hara², Kyle Elliott³, Paul Zandbergen¹, Scott Hatch⁴, Shannon Whelan³

¹Vancouver Island University, ²Environment and Climate Change Canada - University of Victoria, ³McGIll University, ⁴Institute for Seabird Research and Conservation

Breeding seabirds increase foraging range in response to an extreme marine heatwave

**Abstract:**

In iteroparous and long-lived species, such as seabirds, reproductive effort, reproductive success and survival at age class, as well as longevity, play a crucial role in their life history strategies. Isla Rasa, located in the Midriff Islands region of the Gulf of California, is the nesting site of ca. 95% of the world's Hermann's Gull (Larus heermanni) population. This species has demonstrated reproductive strategies such as avoiding breeding until favorable food conditions exist, longevity, late sexual maturation and low reproductive rate. Thus, effects of global and local positive anomalies of sea surface temperature (SST) and fisheries pressure close to the nesting colony have short term effects, during the nesting season. However, differences in reproductive performance have not yet been individually characterized. Our main was to assess the effect of age, longevity and environmental conditions (normal and anomalous high SST years) on the total (lifetime) chicks produced per female. We analyzed females from seven cohorts, banded between 1984 and 1993, and recaptured between 1989 and 2013. We identified two types of strategies: females who laid eggs and hatched chicks both in normal and anomalous years (bold females), and females who did not lay eggs in anomalous years or, if they did, did not hatch chicks (conservative females). Our observations show that bold females are the less common strategy, and live significantly shorter lives. Through a generalized linear mixed model analysis we found that during their lifespan, these females lay significantly fewer eggs than conservative females. Nevertheless, there was no difference in the total number of chicks fledged between bold and conservative females. This suggests that both strategies are adaptive and are coexisting, and maintain a balance in the population. If anomalous years become more frequent in the future, bold females may be at a selective advantage over the conservative ones.

**Authors:**

Gabriela De la Cruz Pino¹, Enriqueta Velarde¹, Ernesto Ruelas¹, Mark Marín-Hernández¹

¹Universidad Veracruzana

Individual Heermann's Gull (Larus heermanni) breeding strategies in a changing world: Are they adaptive any longer?

**Abstract:**

Every August, Hutton's shearwaters (Puffinus huttoni) return from their Australian wintering grounds to breed in the Seaward Kaikoura mountains and on the Kaikoura Peninsula (Te Rae O Atiu). We investigated foraging locations, trip duration, diving behaviour and distance travelled by Hutton's shearwaters from 2014-2018 in the Kaikōura Peninsula colony using 3 approaches: 1) linking isotope analysis of monthly plankton samples from coastal locations with isotope signals from feathers from adults during the breeding season; 2) dive depths from recorders (TDRs) deployed on adult birds during the incubation and chick-rearing periods; and 3) global positioning system (GPS) trackers deployed on adult shearwaters during the chick-rearing period. Comparison of stable isotopic compositions (δ¹³C and δ15N) of potential prey samples with feathers collected from adults showed high levels of variation (δ¹³C from -14.79 to -19.40; δ15N 8.09 to 17.43) suggesting that shearwaters were feeding on a broad range of prey and that the birds were either foraging further offshore or feeding on items not sampled during near-shore plankton tows. This is consistent with recovered foraging tracks from GPS trackers, which show all individuals travelled 125-365 km south-southeast of the breeding colony and "dining out" at more distant locations than previously thought. TDRs indicated that although most dives were within 7.1 m, some birds dived up to depths of 35 m. This provides information on the Hutton's shearwater diving behaviour and their ability to adjust to different foraging depths. Our results have provided key data on the foraging and diving behaviour and diet of this threatened species. Until now, conservation efforts have mostly targeted the terrestrial environments used by Hutton's shearwaters, including predator control and restoration of breeding colonies. Identifying where birds forage, and their prey will help ensure the marine environments used by Hutton's shearwaters are as equally protected.

**Authors:**

Della Bennet¹, Travis Horton², Sharyn Goldstien³, Lindsay Rowe⁴, James Briskie²

¹Wildland Consultants Ltd, ²University of Canterbury, ³DPI Fisheries, ⁴Retired

Long distance dining in the Hutton's shearwater (Puffinus huttoni)

**Abstract:**

For four decades VHF radio tracking has offered a much deeper insight into avifauna than binoculars and a notebook can offer. Since the turn of the century, new technologies have reduced in size and power consumption to the extent that they are becoming suitable for use on progressively smaller species. Tracking highly-migratory or dispersing seabird species becomes a reality where it was difficult-to-impossible using beeper radio tracking. Improved location accuracy and reduced power consumption allow much finer spatial and temporal scale studies to be conducted. For small migratory seabird species, the Motus Wildlife Tracking System provides an international collaborative research network that uses a coordinated array of automated logging radio-receivers to track the movement and behaviour of small flying organisms. Geolocators and Store on Board GPS provide a solution for small migratory seabirds that can be recaptured after a long-term study. For bigger migratory seabirds, GPS with remote download and PTT Satellite tags can provide a solution. However, the challenge of a wider range of options can make the selection of the most appropriate technology difficult. In this talk we look at the different technologies and discuss how they can be used for seabirds no matter what their size is.

**Authors:**

Catalina Amaya-Perilla¹, Sean Walls²

¹Lotek NZ, ²Lotek UK

Tracking seabirds: What technology is out there and what can we do with it

**Abstract:**

The two species of yellow-nosed albatross, Atlantic (Thalassarche chlororhynchos) and Indian (Thalassarche carteri), are morphologically similar, however, they show some differences in behaviour and breeding range. We studied genetic variation within and among the two species using nuclear (microsatellite, Pema7 and Occa9) and mitochondrial (control region) markers. We analysed 201 samples of Atlantic yellow-nosed albatross from Nightingale, Inaccessible and Gough Islands and 33 samples of Indian yellow-nosed albatross from Amsterdam Island. Both sets of markers differentiated the two species. Microsatellite and Occa9 nuclear markers revealed two genetically distinct groups within Atlantic yellow-nosed albatross, grouping birds from Nightingale and Inaccessible Islands together and separating birds from Gough Island. Differences in at-sea distribution might have resulted in genetic differentiation within Atlantic yellow-nosed albatross, but there is no evidence currently of such differences. Both species are listed as endangered due to their limited number of breeding sites and threats from introduced diseases, introduced predators and fishing mortality. Our results contribute to conservation and management plans for the two species, and suggest the need for separate management of the two genetically distinct groups of Atlantic yellow-nosed albatross breeding at the Tristan group (80%) and Gough Island (20%). Key words: yellow-nosed albatross, genetic variation, microsatellite, nuclear marker

**Authors:**

Dilini Abeyrama¹, Zach Dempsey¹, Peter Ryan², Theresa Burg¹

¹University of Lethbridge, ²FitzPatrick Institute of African Ornithology

Speciation and population differentiation in yellow-nosed albatrosses

**Abstract:**

Seabird populations are under threat in many areas, particularly from anthropogenic processes. The majority (60%) of extant penguin species are threatened (IUCN 2013) and the relative importance of threats varies between species and within species' distributions. This study describes the successful management of threats at a declining colony of Little Penguins Eudyptula minor and the colony's growth to the largest of this species. By 1980, the number of colonies of Little Penguins Eudyptula minor on Phillip Island in southeastern Australia had been decimated and the remaining colony was decreasing in size. A plan was initiated focusing on identifying and eliminating/reducing anthropogenic threats to the penguin population. The identified threats were largely terrestrial in origin and included predation by introduced foxes Vulpes vulpes and domestic dogs, mortality caused by motor vehicles and habitat loss associated with a human settlement within the breeding area. Terrestrial threats were addressed by the elimination of the foxes, exclusion of domestic dogs, removal of vehicles from the colony at night and removal of the coastal settlement from the penguin breeding areas. The number of breeding birds grew substantially after the management actions were initiated. The colony was estimated to contain c.12,000 breeding birds in 1985. By 2000, there were c.32,000 breeding penguins and estimates have fluctuated between 28,000-40,000 breeding birds since. Remaining terrestrial threats being addressed are egg predation by abundant corvids and the increasing risk of heat stress during moult and breeding. The success of this program was due to multiple factors which will be discussed.

**Authors:**

Peter Dann¹, Duncan Sutherland¹

¹PHILLIP ISLAND NATURE PARKs

Recovery of the largest colony of the world's smallest penguin

**Abstract:**

The Gulf of Mane (Northwest Atlantic) supports a long-term and large-scale seabird monitoring program, encompassing more than a dozen colonies and thirty years of data. This ecosystem has been subject to marine heatwaves and steep declines in commercially fished Atlantic herring (Clupea harengus), allowing for a variety of investigations into seabird-ecosystem relationships. We present two studies involving large-scale data collection that each revealed new insights into ecosystem quality and function. One study linking seabird chick provisioning data to fishery and fishery-independent herring data indicated that herring declines were not uniform across the ecosystem; the relevant management units used by the fishery obscured smaller-scale changes to herring abundance that were particularly severe in the east. Seabird data also potentially illustrate movements of juvenile herring and show that Canadian-origin herring spend their first summers in the USA. Our second study examines the population dynamics and habitat quality of Arctic Terns (Sterna paradisaea), typically a widely dispersed and inaccessible seabird. We determined the source-sink status of each colony annually in our metapopulation, and linked it to habitat quality over 27 years. Each colony had unique diet profiles that prevented any single variable from being used as an index, but when examined together indicated high-quality and low-quality years. Impacts of mesopredator Laughing Gulls (Leucophaeus atricilla) were nearly impossible to quantify at a local scale, but became clearer at a metapopulation scale, inhibiting reproductive success and demographic contribution. These insights would not have been possible without data from multiple colonies, which allowed for synergistic conclusions.

**Authors:**

Lauren Scopel¹, Antony Diamond¹, Stephen Kress², Paula Shannon³, Linda Welch⁴, Sara Williams⁴

¹University of New Brunswick, ²Cornell University, ³National Audubon Society Seabird Restoration Program, ⁴U.S. Fish and Wildlife Service

Dynamics of prey and predator movements in linked metapopulations

**Abstract:**

Density dependent prey depletion around breeding colonies has long been proposed as an important factor controlling the population dynamics of colonial animals. Colonial breeding provides benefits to members via information sharing and reduced predation, but may create costs via negative density-dependence. Using tracking data from murres (Uria spp.), the world's most densely breeding seabirds, we show that the frequency distribution of foraging trip distances scales to the 0.31 power of colony size during the chick-rearing stage, consistent with Ashmole's Halo theory. This pattern was evident across colonies varying in size over three orders of magnitude and distributed throughout the North Atlantic region. The strong relationship between colony size and foraging range means that important foraging habitat for some colonial species can be efficiently delineated based solely on population estimates. Protected areas covering the foraging ranges of the 17 largest colonies would safeguard two-thirds of the North Atlantic population; currently, only two of those colonies have significant coverage by marine protected areas. Our results represent an important example of how behavioural modelling, in this case Ashmole's version of central place foraging theory, can be applied to inform conservation and management in colonial breeding species.

**Authors:**

Allison Patterson¹, Grant Gilchrist², Anthony Gaston², Sigurd Benjaminsen³, Mark Bolton⁴, Sebastien Descamps³, Kjell Erikstad⁵, Morten Frederiksen⁶, Jannie Linnebjerg⁶, Oliver Love⁷, Mark Mallory⁸, Flemming Merkel⁶, William Montevecchi¹, Anders Mosbech⁶, Ellie Owen⁴, Paul Regular⁹, Tone Reiertsen⁵, Yan Ropert-Coudert¹⁰, Thorkell Thórarinsson¹¹, Anne Sophie Bonnet-Lebrun¹², Gail Davoren¹³, Julia Gulka¹³, Jonas Hentati-Sundberg¹⁴, Nicholas Huffeldt⁶, Kasper Johansen⁶, Aili Labansen¹⁵, Olof Olsson¹⁶, Norman Ratcliffe¹², Hallvard Strøm¹⁷, Kyle Elliott¹

¹McGill University, ²Environment and Climate Change Canada, ³Norwegian Polar Institute, ⁴Royal Society for the Protection of Birds, ⁵Norwegian Institute for Nature Research, ⁶Aarhus University, ⁷Windsor University, ⁸Acadia University, ⁹Fisheries and Oceans Canada, ¹⁰Centre d'Etudes Biologiques de Chizé, ¹¹Northeast Iceland Nature Research Centre, ¹²British Antarctic Survey, ¹³University of Manitoba, ¹⁴Swedish University of Agricultural Sciences, ¹⁵Greenland Institute of Natural Resources, ¹⁶Stockholm University, ¹⁷Norwegian Polar Institute, FRAM Centre

Foraging range scales with seabird colony size

**Abstract:**

Plasticity in foraging behavior among individuals within a colony can reduce competition but few studies have compared the generality of foraging patterns among individuals from multiple breeding colonies. Western gulls (Larus occidentalis) are generalist foragers that consume a range of marine and terrestrial foods but multi-colony comparisons are limited. Here, we used tail-mounted GPS loggers to compare the foraging behavior of 156 western gulls breeding at seven colonies ranging from southern California to Oregon, USA. Colonies varied dramatically in population size (100 to 10,000 nests) and distance from the mainland (<1 to 60 km). Foraging behavior was significantly influenced by proximity to urban centers (e.g. Los Angeles & San Francisco) where gulls traveled farther (>150 km roundtrip) and for longer durations (12-24 hrs) compared to foraging excursions at sea. More than 50% of all gulls (predominantly from the largest colonies) exhibited a mixture of marine and terrestrial foraging whereas gulls from both smaller colonies in Oregon foraged mainly at sea. Foraging sites on land included landfills, waste management centers, and parks whereas marine habitats were primarily over neritic waters or along coastlines. Colony-specific home range varied with colony size (2,034 km^2 vs. 14,230 km^2, smallest and largest colony, respectively) as did mean individual home ranges (309 ± 311 SD km^2 vs. 986 ± 786 SD km^2, respectively), consistent with greater resource competition. Population-level plasticity in foraging behavior was evident and dependent on habitat type. In general, gulls from the larger more distant colonies were away longer when foraging in terrestrial habitats than gulls foraging at sea, and this may impact territorial defense and attempts at nest predation by conspecifics.

**Authors:**

Scott Shaffer¹, Rachael Orben², Pete Warzybok³, Russell Bradley⁴, Jaime Jahncke³, Leigh Torres², Robert Suryan⁵, Corey Clatterbuck⁶, Hillary Young⁷

¹San Jose State University, ²Oregon State University, ³Point Blue Conservation Science, ⁴California State University - Channel Islands, ⁵National Oceanic and Atmospheric Administration, ⁶San Diego State University, ⁷University of California

Devil's in the details: A multi-colony perspective on the foraging ecology of western gulls

**Abstract:**

Multi-colony studies of breeding seabirds may provide insights into the mechanistic links between large-scale climate variability and local changes in prey availability. In the North Pacific, the Pacific Decadal Oscillation (PDO) is a dominant climate index, characterized by contrasting effects on sea surface temperature between the western and eastern North Pacific. To examine how inter-annual variability in PDO affects rhinoceros auklets Cerorhinca monocerata across the North Pacific, we measured inter-annual changes in nutritional stress (as reflected in plasma levels of corticosterone) of adults breeding on five colonies (two and three colonies from the western and eastern Pacific, respectively). We also examined concurrent changes in mass and energy content of food loads delivered to chicks. We found that higher summer PDO values were associated with increased corticosterone levels and lower mass and energy contents of the food loads in both the western and eastern North Pacific colonies. Results indicate that higher summer PDO is associated with local changes in forage fish communities leading to reduced availability of energy-rich prey, which, in turn, increases the nutritional stress of breeding birds. We conclude that higher summer PDO index is associated with food-poor conditions for breeding rhinoceros auklets across their reproductive range, and prolonged periods of high summer PDO may be detrimental to the populations of this seabird species.

**Authors:**

Ui Shimabukuro¹, Akinori Takahashi², Jumpei Okado³, Nobuo Kokubun², Jean-Baptiste Thiebot⁴, Alexis Will⁵, Yutaka Watanuki³, BriAnne Addison⁶, Scott Hatch⁷, J. Mark Hipfner⁸, Leslie Slater⁹, Brie Drummond⁹, Alexander Kitaysky⁵

¹The Graduate University for Advanced Studies, SOKENDAI, ²The Graduate University for Advanced Studies, SOKENDAI & National Institute of Polar Research, ³Hokkaido University, ⁴National Institute of Polar Research, ⁵University of Alaska Fairbanks, ⁶Deakin University, ⁷Institute for Seabird Research and Conservation, ⁸Pacific Wildlife Research Centre, ⁹U.S. Fish and Wildlife Service

Flexibility of Guanay Cormorant foraging behavior under an unpredictable marine environment

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Flexibility of Guanay Cormorant foraging behavior under an unpredictable marine environment

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Breeding seabirds increase foraging range in response to an extreme marine heatwave

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Environmental effects on foraging performances in an inshore seabird: a combination of phenology and short-term variability.

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