We determined the stock composition of juvenile salmon taken by a pursuit-diving seabird, the Rhinoceros Auklet (Cerorhinca monocerata), on five breeding colonies in British Columbia in 2012-2014. Our goal was to test the hypothesis that these birds take salmon in proportion to their abundance, with specific focus on first, the biennial cycle of pink salmon; and second, the enormous out-migration of juvenile sockeye from BC's Fraser River in 2012. We obtained 772 meals in 11 colony-years of sampling, of which 198 (26%) included one or more salmon, and determined stock composition for 126 pink, 101 sockeye, and 113 chum. As expected, the biennial cycle of pink salmon was evident in the birds' diets: individuals from Puget Sound were common on colonies in 2012 and 2014 but absent in 2013 and replaced by pinks from northerly stocks. Also as expected, Fraser River sockeye were unusually abundant in the birds' diets in 2012. Our results show that these seabirds can respond to pulses of increased abundance of juvenile salmon, although they are not usually primary prey types.

Population trends in two closely related and ecologically similar North Pacific auks, the Rhinoceros Auklet Cerorhinca Tufted Puffin Fratercula cirrhata, , have diverged over recent decades: stable in the former, declining in the latter. I propose between the two species in a broad suite of interrelated morphological, demographic, behavioral, and physiological life-history explain their differing responses to recent environmental conditions.

The Coats Island field station in northern Hudson Bay, Canada, was established by the Canadian Wildlife Service in 1984 to monitor the thick-billed murre ( Uria lomvia, akpa, [Formula: see text]) population in the context of harvest management and federal responsibilities under the Migratory Birds Convention Act. The long-term monitoring program has continued annually for 34 of the last 39 years, making it the most frequently monitored seabird colony in the Canadian Arctic. In the 1990s, the focus of efforts at the site shifted from population monitoring and harvest management to long-term monitoring of murres as an indicator of environmental change. In addition to informing harvest management of murres in Canada, long-term monitoring and research at Coats Island have helped to establish thick-billed murres as an indicator species for Arctic seabirds, identified major shifts in the marine prey communities of Hudson Bay, enabled the assessment of international agreements on reducing contaminants in Arctic wildlife, and improved the understanding of the effects of climate change on Arctic marine birds. Coats Island has developed into an essential research site for all aspects of murre ecology and served as a training site for new generations of Arctic ecologists.

Animals are strongly connected to the environments they live in and may become adapted to local environments. Examining genetic-environment associations of key indicator species, like seabirds, provides greater insights into the forces that drive evolution in marine systems. Here we examined a RADseq dataset of 19,213 SNPs for 99 rhinoceros auklets (Cerorhinca monocerata) from five western Pacific and 10 eastern Pacific breeding colonies. We used partial redundancy analyses to identify candidate adaptive loci and to quantify the effects of environmental variation on population genetic structure. We identified 262 candidate adaptive loci, which accounted for 3.0% of the observed genetic variation among western Pacific and eastern Pacific breeding colonies. Genetic variation was more strongly associated with pH and maximum current velocity, than maximum sea surface temperature. Genetic-environment associations explain genetic differences between western and eastern Pacific populations; however, genetic variation within the western and eastern Pacific Ocean populations appears to follow a pattern of isolation-by-distance. This study represents a first to quantify the relationship between environmental and genetic variation for this widely distributed marine species and provides greater insights into the evolutionary forces that act on marine species.

Clinical metrics of baseline health in sentinel seabird species can offer insight into marine ecosystem dynamics, individual and population health, and assist in wildlife rehabilitation and conservation efforts. Protein electrophoresis is useful for detecting changes in acute phase proteins and immunoglobulin levels that may indicate subtle inflammatory responses and/or infectious disease. Serum biochemistry can highlight nutritional status, metabolic derangements, and organ injury and function. However, baseline values for such health parameters are largely unknown for many seabird species. Therefore, the objective of this study is to establish baseline clinical health reference intervals for serum protein electrophoresis, acute phase proteins including serum amyloid A and haptoglobin, and biochemistry parameters in the rhinoceros auklet (Cerorhinca monocerata), a key sentinel species in the North Pacific. From 2013 to 2019, 178 wild, apparently healthy breeding adult rhinoceros auklets were captured across four breeding colonies in British Columbia, Canada (Lucy Island, Pine Island, Triangle Islands, and SGang Gwaay) and from one colony in Washington, United States (Protection Island). Reference intervals were calculated for protein electrophoresis fractions and acute phase proteins (n = 163), and serum biochemistry (n = 35) following established guidelines by the American Society of Veterinary Clinical Pathology. Animals were also assessed for the presence of antibodies to the influenza A virus. Approximately 48% (70/147) of sampled birds were seropositive for influenza A virus, with a prevalence of 50% (6/12) in 2013, 75% (47/63) in 2014, and 24% (17/72) in 2019. This work provides clinical baseline health metrics of a key North Pacific sentinel species to help inform marine ecosystem monitoring, recovery, and rehabilitation efforts in the Pacific Northwest.

Addressing urgent conservation issues, like the drastic declines of North American migratory birds, requires creative, evidence-based, efficient, and collaborative approaches. Over 50% of monitored North American shorebird populations have lost over 50% of their abundance since 1980. To address these declines, we developed a partnership of scientists and practitioners called the Shorebird Science and Conservation Collective (hereinafter “the Collective”). Here, we present this successful case study as an example for others engaged in translational science. The Collective acts as an intermediary whereby dedicated staff collate and analyze data contributions from scientists to support knowledge requests from conservation practitioners. Data contributions from 74 organizations include over 6.7 million shorebird locations forming movement paths of 3,345 individuals representing 36 species tracked across the Americas. We describe the founding and structure of the Collective and conservation activities we supported in our first two years. As the volume of scientific data on animal movements continues to grow, groups like the Collective can be vital liaisons to rapidly integrate and interpret research to support conservation action.### Competing Interest StatementThe authors have declared no competing interest.

AbstractEnvironment and behavior are widely understood to affect bird morphology, which can lead to differences among subspecies or populations within a wide‐ranging species. Several patterns of latitudinal gradients in morphology have been described, though Allen's and Bergmann's rules are the most well‐known and have been tested and confirmed across a diversity of taxa and species. These state that individuals at higher latitudes will have larger bodies (Bergmann's Rule) but smaller extremities (Allen's Rule) to conserve heat in colder climates. Migratory behavior also can influence avian morphology, particularly wing shape, where migratory birds tend to have longer, more pointed wings than residents. The Black Oystercatcher (Haematopus bachmani) is a large, partially migratory shorebird species restricted to intertidal habitats and distributed from Alaska to Baja California, spanning about 35° of latitude. A large proportion of Black Oystercatchers that breed in Alaska are migratory, where nearly all individuals breeding in British Columbia through the southern end of their range remain resident through the annual cycle. Their broad latitudinal range and diversity in migratory behavior may drive geographic variation in morphology. Here we evaluate three explanations for geographic variation in morphology of the Black Oystercatcher using data from seven sites across two regions: Alaska and British Columbia. We found evidence consistent with Allen's but not Bergmann's rule; birds in Alaska have shorter bills than those in British Columbia, and these findings held when controlling for body size using wing length. Despite regional differences in migratory behavior, we detected no difference in the wing shape of birds in Alaska and British Columbia. Differences between sexes and among sites suggest that multiple factors drive patterns of morphological variation in the Black Oystercatcher.

Models of migratory behavior predict trade-offs between fitness costs and benefits with respect to migration distance. Shorter migration distances may confer a fitness benefit by facilitating earlier breeding, however this is rarely investigated. We tested this hypothesis using a large-scale geolocation (GLS) dataset from 109 rhinoceros auklets (Cerorhinca monocerata), a differentially migrating seabird, that was tagged at 12 breeding colonies along the Pacific Coast of North America, spanning southern California to the eastern Aleutian Islands, Alaska. Using GLS-based position estimates, we determined the geographic centroid of the pelagic areas occupied by birds in winter (1 January-28 February) and then calculated the distance between their wintering centroids and colony of origin. We then used GLS light-intensity and salt-water immersion (wet/dry) data to determine each individual's date of egg-laying the following spring. Rhinoceros auklets were very widely distributed across the northeastern Pacific Ocean in winter. Among all individuals, the distance between winter centroids and breeding colonies ranged from < 100 to > 2500 km, being greater among individuals originating from colonies at higher latitudes. As predicted, migration distance and colony latitude were positively related to lay date: after accounting for colony-level differences in phenology, individuals that migrated shorter distances tended to lay their eggs earlier, a pattern that emerged across all populations. Our study links the migration distance of rhinoceros auklets to a fitness-related outcome, underscoring the selective pressure that migration exerts on subsequent breeding activity.

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 patterns in sea surface temperature between the western and eastern North Pacific. To examine how inter-annual variability in the 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 5 colonies (2 and 3 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 indicated that oceanographic conditions during higher PDO values induced local changes in forage fish communities, leading to reduced prey availability, which, in turn, increased the nutritional stress of breeding birds. We conclude that the higher summer PDO index in recent years was 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. Our results highlight the complexity of the mechanisms of how large-scale climate variability affects seabirds with a large geographical distribution.

Habitat use of indicator species is used to prioritize management activities. However, habitat use can vary temporally in response to changes in predation risk and foraging rewards. We deployed satellite tags on 20 black oystercatchers (Haematopus bachmani) in four regions of British Columbia, Canada, to examine habitat use and selection decisions across seasonal, diel and tidal cycles. We characterized the shoreline in each region and used GLMMs to investigate how habitat characteristics influenced shoreline use by tracked birds. For individuals, we estimated home range size and the frequency key features of the shoreline were re-visited. Black oystercatchers generally made greater-than-expected use of rocky islets and shoreline with freshwater outflows, less tree cover and greater intertidal area. However, while black oystercatchers preferred islets and shoreline with less tree cover at most/all time periods, they only exhibited preferences for greater intertidal area during low tides, and preferences for shoreline with freshwater outflows during the nonbreeding season, day, and high tides. Individual home ranges, on average, contained 46 km of shoreline (range: 12-156 km) and individuals used 10.4 km (range: 6.7-13.9 km). Individuals made greater use of larger islets with less tree cover that were closer to outflows, and greater use of outflows associated with larger streams, greater intertidal areas and gravel substrates. Black oystercatchers' habitat preferences likely reduce predation risk (rocky islets and shoreline with less tree cover) and increase foraging rewards (shoreline with freshwater outflows, greater intertidal area, and gravel substrates). However, habitat preferences appear sensitive to constraints on movement in the breeding season and changes in foraging rewards across the diel and tidal cycle, highlighting the importance of examining habitat use at multiple temporal scales. Black oystercatchers are considered indicators of rocky intertidal health; therefore, critical habitat is expected to be important for a suite of wildlife dependent on safe and productive coastline.

Tufted Puffins (Fratercula cirrhata) are experiencing population declines in some parts of their distribution, making this a species of increased conservation interest. Genetic data will help to identify Tufted Puffin populations of conservation importance and provide an important tool for developing conservation management plans. This species is broadly distributed across the North Pacific Ocean but little is known about the extent of genetic variation and differentiation across their range. In this study, we examine mitochondrial DNA (mtDNA), 8 microsatellite loci and 1,260 single nucleotide polymorphisms (SNPs) to determine the extent of gene flow among 7 breeding colonies (Oregon to the western Aleutians) in the North American breeding range of the species and identify potential barriers to dispersal. Our results show that most breeding colonies form a single genetic cluster, and mtDNA data show substantial historical gene flow among populations. For the microsatellite dataset, all F-ST comparisons that include St. Lazaria, in southeast Alaska, except Oregon, which had a small sample size, were significant as were comparisons between Triangle Island and the two westernmost sampling sites of Buldir and Aiktak. For the SNP dataset, F-ST comparisons were low and nonsignificant, further suggesting that breeding colonies form a single panmictic population. Individuals were more closely related to individuals from the same colony, and we found a weak relationship between genetic and geographic distance. This suggests that dispersal among colonies is high, likely facilitated by an overlap in wintering ranges among colonies. The high connectivity among breeding colonies indicates that Tufted Puffins form a single conservation unit, although future genetic studies should incorporate a whole genome sequencing approach to assessing how functional genetic diversity varies across their distribution. Lay Summary & BULL; Tufted Puffins (Fratercula cirrhata) are experiencing population declines in some parts of their distribution, making this a species of increased conservation interest. & BULL; Here we use 3 different types of genetic markers (mtDNA, microsatellites, and SNPs) to examine population genetic structure among 7 breeding colonies (Oregon to the western Aleutians) in the North American breeding range of the species. & BULL; We examined population genetic structure to determine whether Tufted Puffin populations form single or multiple conservation units. & BULL; All 3 types of markers showed a similar pattern and indicate that North American breeding colonies form a single genetic cluster. & BULL; Our results suggest that dispersal among colonies is high, likely facilitated by an overlap in wintering ranges among colonies. & BULL; The high connectivity among breeding colonies indicates that Tufted Puffins form a single conservation unit, although future genetic studies should include samples from Asia to assess population genetic structure across their whole distribution.

Many bird species use features of the physical environment to cue breeding activity. We show that for 2 species of Pacific auks (zooplanktivorous Cassin's auklet Ptychoramphus aleuticus and generalist rhinoceros auklet Cerorhinca monocerata), spatio-temporal variation in marine production indicators surrounding a major breeding colony in the northeast Pacific Ocean can cue laying date. By utilizing a multi-year phenological time series and a spatio-temporal sliding-window analysis spanning November up until median lay dates in spring, chlorophyll a (chl a) concentrations in the surface ocean around the colony strongly predicted lay date. However, the response to this cue differed between species by over 2 mo, as each species was exposed to different, sequential water-masses. We show that for Cassin's auklets, chl a levels at Triangle Island, British Columbia (Canada) in February, nearly 2 mo prior to actual laying, strongly correlated with lay date in April (average r = 0.83). At this time, the ocean environment around Triangle Island is dominated by water-masses from the south-southeast. However, for sympatric rhinoceros auklets, chl a along broad shelf-break areas in April prior to lay dates in May strongly correlated with lay date (average r = 0.76). Occurring after the spring transition, these water-masses flow primarily from the northwest. Consistent with other bird species, both auks appear to respond to information about food production, but at different spatio-temporal scales. We suggest that these different responses to environmental cues reflect species-specific differences in female migration behaviour, and an attempt by Cassin's auklets to bet-hedge against phenological mismatches.

The Black-legged Kittiwake Rissa tridactyla is a widely distributed and well-studied northern hemisphere seabird. Authoritative publications document the existence of breeding colonies in Canada's Arctic and Atlantic regions but not in the Pacific region. We visited the small (ca. 50 pairs in recent years) kittiwake breeding colony at Holland Rock, British Columbia, in July and August 2021, and documented what we believe to be the first record of successful breeding at this site. Previous records have documented successful breeding no further south than 58 degrees latitude in Alaska, similar to 600 km to the north, making Holland Rock the southernmost colony in the eastern Pacific.

Summary Regional and local studies suggest that the Tufted Puffin Fratercula cirrhata in North America is declining in portions of its range. However, whether the overall population is declining, or its range is contracting with little change to the overall population size, is unknown. To examine population trends throughout its North American range, we assembled 11 datasets that spanned 115 years (1905–2019) and included at-sea density and encounter estimates and at-colony burrow and bird counts. We assessed trends for the California Current, Gulf of Alaska, and Bering Sea/Aleutian Islands large marine ecosystems (LME). We found: (1) nearly uniform and long-term declines of Puffins breeding in the California Current ecosystem, with most ecosystem colonies surveyed, (2) declining trends at two large colonies and in one at-sea dataset in the Gulf of Alaska LME, with the fourth smaller colony exhibiting no significant trend, and (3) positive trends at four out of five colonies in the Bering Sea/Aleutian Islands ecosystem complex, with no detectable trend at the fifth very large colony. The general pattern of Tufted Puffin declines across the California Current and Gulf of Alaska LMEs may be attributable to a variety of factors, but additional study is needed to evaluate the relative influence of potential population drivers both independently and synergistically. Potential mechanisms driving population increases in the Bering Sea/Aleutian Islands ecosystem include reduced depredation and bycatch, intrinsic population growth, and immigration. We found strong evidence for declines in two of the three LMEs evaluated representing approximately three quarters of the species’ North American range. This region of decline includes the Gulf of Alaska LME, which contains a significant portion of the species’ estimated total North American population. Despite data limitations, our analysis coupled with more focused and local studies indicates that the Tufted Puffin is a species of conservation concern.

Understanding the movements and habitat use of marine birds is essential to inform conservation and marine spatial planning. Here, satellite transmitters were used to study the migration and winter habitat use of adult Glaucous-winged Gulls (Larus glaucescens) from a colony in central British Columbia. Three of four tracked gulls overwintered locally, while the fourth followed a coastal migration route to northern California. All four gulls maintained small winter home ranges and spent an average of 72% of their time in nearshore coastal waters (average distance to coast: 0.6-1.7 km) characterized by low levels of anthropogenic activity. The remainder of their time was spent in naturally vegetated areas. One gull overwintered in an area with high human population density (northern California), with limited use of cropland (4% of locations) and urban (6% of locations) areas. This study is part of on-going efforts to understand the distribution and habitat use of marine birds throughout British Columbia to inform marine spatial planning and associated threats at various scales.

Abstract Triangle Island on Canada's Pacific coast is home to a large, globally important seabird breeding colony. The shrub Salmonberry Rubus spectabilis and tussock‐forming Tufted Hairgrass Deschampsia cespitosa together form ~70% of vegetation coverage and contain the vast majority (~90%) of seabird nesting burrows. Salmonberry has in recent decades greatly expanded its coverage, while that of Tufted Hairgrass has receded. Seabirds prefer not to burrow under Salmonberry, making its ongoing expansion a potential conservation issue. We investigated three hypotheses proposed to explain Salmonberry's expansion (climate change, biopedturbation, and nutrient input), using comparisons of stomatal density of Salmonberry leaves sampled from Triangle Island, other seabird colonies, other coastal locations, and from historical specimens in herbaria. Stomatal density helps regulate photosynthetic gain and control water loss, and responds to light, nutrient, carbon dioxide, and water availability. Differing patterns of stomatal density are expected among sample locations depending on which of the hypothesized factors most strongly affects Salmonberry's performance. Our data are most consistent with the nutrient input hypothesis. We discuss possible reasons why Salmonberry has expanded so recently, even though Triangle has been a large seabird colony for at least a century and likely much longer.

Seabirds are wide-ranging organisms often used to track marine pollution, yet the effect of migration on exposure over the annual cycle is often unclear. We used solar geolocation loggers and stable isotope analysis to study the effects of post breeding dispersal and diet on persistent organic pollutant (POP) and mercury (Hg) burdens in rhinoceros auklets, Cerorhinca monocerata, breeding on islands along the Pacific Coast of Canada. Hg and four classes of POPs were measured in auklet eggs: organochlorine insecticides (OCs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluoralkyl substances (PFASs). Stable isotope values of adult breast feathers grown during winter were used in conjunction with geolocation to elucidate adult wintering latitude. Wintering latitude was the most consistent and significant predictor of some POP and of Hg concentrations in eggs. The magnitude and pattern of exposure varied by contaminant, with ∑PCBs, ∑PBDEs and DDE decreasing with wintering latitude, and mirex, perfluoro-n-tridecanoic acid, and Hg increasing with latitude. We suggest that concentrations of these contaminants in rhinoceros auklet eggs are influenced by variation in uptake at adult wintering locations related to anthropogenic inputs and oceanic and atmospheric transport.

Abstract ‘The Blob’, a mass of anomalously warm water in the Northeast Pacific Ocean peaking from 2014 to 2016, caused a decrease in primary productivity with cascading effects on the marine ecosystem. Among the more obvious manifestations of the event were seabird breeding failures and mass mortality events. Here, we used corticosterone in breast feathers (fCort), grown in the winter period during migration, as an indicator of nutritional stress to investigate the impact of the Blob on two sentinel Pacific auk species (family Alcidae). Feathers were collected from breeding females over 8 years from 2010 to 2017, encompassing the Blob period. Since Pacific auks replace body feathers at sea during the migratory period, measures of fCort provide an accumulated measure of nutritional stress or allostatic load during this time. Changes in diet were also measured using δ15N and δ13C values from feathers. Relative to years prior to the Blob, the primarily zooplanktivorous Cassin’s auklets (Ptychoramphus aleuticus) had elevated fCort in 2014–2017, which correlated with the occurrence of the Blob and a recovery period afterwards, with relatively stable feather isotope values. In contrast, generalist rhinoceros auklets (Cerorhinca monocerata) displayed stable fCort values across years and increased δ15N values during the Blob. As marine heatwaves increase in intensity and frequency due to climate change, this study provides insight into the variable response of Pacific auks to such phenomena and suggests a means for monitoring population-level responses to climatological variation.

We tested the hypothesis that segregation in wintering areas is associated with population differentiation in a sentinel North Pacific seabird, the rhinoceros auklet (Cerorhinca monocerata). We collected tissue samples for genetic analyses on five breeding colonies in the western Pacific Ocean (Japan) and on 13 colonies in the eastern Pacific Ocean (California to Alaska), and deployed light-level geolocator tags on 12 eastern Pacific colonies to delineate wintering areas. Geolocator tags were deployed previously on one colony in Japan. There was strong genetic differentiation between populations in the eastern vs. western Pacific Ocean, likely due to two factors. First, glaciation over the North Pacific in the late Pleistocene might have forced a southward range shift that historically isolated the eastern and western populations. And second, deep-ocean habitat along the northern continental shelf appears to act as a barrier to movement; abundant on both sides of the North Pacific, the rhinoceros auklet is virtually absent as a breeder in the Aleutian Islands and Bering Sea, and no tagged birds crossed the North Pacific in the non-breeding season. While genetic differentiation was strongest between the eastern vs. western Pacific, there was also extensive differentiation within both regional groups. In pairwise comparisons among the eastern Pacific colonies, the standardized measure of genetic differentiation (FꞌST) was negatively correlated with the extent of spatial overlap in wintering areas. That result supports the hypothesis that segregation in the non-breeding season is linked to genetic structure. Philopatry and a neritic foraging habit probably also contribute to the structuring. Widely distributed, vulnerable to anthropogenic stressors, and exhibiting extensive genetic structure, the rhinoceros auklet is fully indicative of the scope of the conservation challenges posed by seabirds.