New insights from old eggs – the shape and thickness of Great Auk Pinguinus impennis eggs

Since the late 1600s it has been assumed that the Great AukPinguinus impenniswas similar to the Common GuillemotUria aalgeand Brünnich's GuillemotUria lomviain having a single, central brood patch. Through the examination of eight mounted museum specimens, we show that this is incorrect and that, like its closest relative the RazorbillAlca torda, the Great Auk had two lateral brood patches. We discuss how such misinformation persisted for so long. We also review the relationship between the number of brood patches and clutch size in the Alcidae. One implication of two brood patches is that the Great Auk would have incubated in a horizontal posture like the Razorbill, rather than in a semi‐upright posture like theUriaguillemots. Assuming that the Great Auk incubated like the Razorbill, it would probably have done so horizontally with its single egg pressed against one of the two lateral brood patches, positioned against the inside of one tarsus (and partially on the web of one foot), and with the wing on that side drooped to provide additional protection for the egg. Incubating in this way may have meant that the Great Auk's pyriform egg would have enabled it to use both level and sloping terrain, as in theUriaguillemots (but unlike the Razorbill). A horizontal incubation also has implications for estimates of their breeding density, which we estimate to have been around four pairs per square metre and, hence numbers on its largest known colony, Funk Island, Newfoundland (maximum 250 000 pairs).

Sexual Differences in Parental Activities of Breeding Black Skimmers

The Razorbill Alca torda is one of three auk species breeding in Sweden, often occurring in colonies with Common Guillemot Uria aalge. The largest colony in the Baltic Sea is situated on the island Stora Karlsö west of Gotland. During the chick-rearing phase, Razorbills forage at sea and return to feed the young with single or multiple prey carried sideways in the bill, unlike Common Guillemots that carry a single fish in the middle of the bill. Clupeids, especially sprat Sprattus sprattus, are the main prey of Baltic Sea Razorbills, but studies are scarce. Here, we investigate the diet preference of Razorbills at Stora Karlsö with regard to prey taxonomy and size, analysing photographs and applying morphometric equations. We show that most feeding attempts involved a single clupeid (88% of known fish taxonomy), in most cases likely sprat. The average prey size (115 mm) and prey species was similar to that of Common Guillemots in the same colony. The variation in size was much smaller in the Razorbill diet than the size distribution of clupeids at sea, indicating a strong prey size selectivity. The Razorbills’ high specialisation underlines the importance of maintaining strong populations of clupeids in their foraging area, as these fish are also targeted by industrial fisheries.

The Atlantic auk assemblage includes four extant species, razorbill (Alca torda), dovekie (Alle alle), common murre (Uria aalge), and thick-billed murre (U. lomvia), and one recently extinct species, the flightless great auk (Pinguinus impennis). To determine the phylogenetic relationships among the species, a contiguous 4.2-kb region of the mitochondrial genome from the extant species was amplified using PCR. This region included one ribosomal RNA gene, four transfer RNA genes, two protein-coding genes, the control region, and intergenic spacers. Sets of PCR primers for amplifying the same region from great auk were designed from sequences of the extant species. The authenticity of the great auk sequence was ascertained by alternative amplifications, cloning, and separate analyses in an independent laboratory. Phylogenetic analyses of the entire assemblage, made possible by the great auk sequence, fully resolved the phylogenetic relationships and split it into two primary lineages, Uria versus Alle, Alca, and Pinguinus. A sister group relationship was identified between Alca and Pinguinus to the exclusion of ALLE: Phylogenetically, the flightless great auk originated late relative to other divergences within the assemblage. This suggests that three highly divergent species in terms of adaptive specializations, Alca, Alle, and Pinguinus, evolved from a single lineage in the Atlantic Ocean, in a process similar to the initial adaptive radiation of alcids in the Pacific Ocean.

Avian eggs exhibit substantial intra‐ and interspecific variation in shape, size and colour. Considerable efforts have been made to better understand the evolutionary drivers behind such variation, often using museum egg collections. Usually it is assumed that museum collections accurately represent the variation seen in natural populations, but this may not be the case if there is collection bias. Collection bias may lead to the over‐representation of certain egg traits in collections, due to the aesthetic (or other) preferences of collectors. The aim of this study is to begin to look for the occurrence of potential collection bias in museum egg collections by comparing three shape indices (pointedness/asymmetry, elongation and polar asymmetry) and egg volume between subsets of eggs in museum collections with those of recently sampled eggs in the field for three different bird species: common guillemotUria aalge, razorbillAlca tordaand northern fulmarFulmarus glacialis. We found no evidence of collection bias in our sampled razorbill and northern fulmar museum collection eggs, but some evidence for a bias in sampled museum collection eggs of common guillemots. Since the guillemot's egg differs from most bird eggs in being pyriform, we suggest that collection bias by historic egg collectors may be more prevalent in species with extreme egg traits. Researchers using museum egg collections to examine questions relating to egg shape should be aware of collection bias risks and consider how to minimise the effect of these possible biases on accumulated datasets.

-Common Murres (Uria aalge) exhibit an unusual molt sequence. Primary molt begins at a focus between P4 and P7 and progresses in two rapid concurrent waves, proximally to P1, and distally to P10. The only other birds known to have a similar molt sequence are caracaras and falcons (Falconidae), parrots (Psittaciformes), and Pied Kingfishers (Ceryle rudis). Great Auks (Pinguinus impennis) also appear to have followed the same primary-molt sequence. Phylogenies for the Alcidae indicate that Great Auks, Common Murres, Thickbilled Murres (Uria lomvia), Razorbills (Alca torda), and Dovekies (Alle alle) share a common ancestor and are more closely related to one another than to other alcids. This suggests that the unusual sequence of primary molt in Common Murres is a shared-derived character that occurs in the other four species in their clade but has been overlooked. Adult male Common Murres have significantly shorter secondaries and longer primaries, on average, than do adult females, resulting in a slightly higher aspect ratio in males. Secondary molt begins when primary molt is more than one-third completed. Secondaries are replaced rapidly but sequentially (not synchronously or simultaneously); molt appears to proceed from two foci, proximally from S1 to S4, and both proximally and distally from S8, but more data are needed to clarify this point. Rectrix molt begins when primary molt is two-thirds completed. Rectrix loss and replacement occur rapidly, possibly synchronously, and in no apparent order. Adults molt about two weeks later than nonbreeding subadults. We found no differences in the timing of molt between the sexes in adults or subadults. Duration of flight-feather molt can vary from less than 25 days to more than 80 days, possibly reflecting interyear variation in prey abundance. Received 12 February 1997, accepted 9 December 1997. RELATIVE TO MOST OTHER TOPICS in ornithology, virtually all aspects of the molting process are poorly documented and understood (Pyle et al. 1987, Jenni and Winkler 1994). This is especially true in seabirds because most species, including all species that become flightless during molt, undergo molt at sea during the nonbreeding season (Palmer 1962, Glutz von Blotzheim and Bauer 1982, Cramp 1977, 1983, Warham 1996). Among alcids, molt has been better studied in Common Murres (Uria aalge) than in many other species (Verwey 1922, 1924, Salomonsen 1944, Stresemann and Stresemann 1966, Birkhead and Taylor 1977), but many aspects of their molt remain poorly known (contra Harris and Wanless 1990). As an extension of studies on seabird entanglement in gill nets in Puget Sound (Thompson et al. 1998), we studied molt in Common 4E-mail: thompcwt@dfw.wa.gov Murres. The phenology of breeding in Common Murres differs by two months or more among geographic areas. Thus, flight-feather molt scores in postbreeding adults might be useful for identifying breeding location (e.g. Oregon vs. Washington); this is important for determining the demographic effect of mortality caused by gill nets or other anthropogenic activities on different breeding populations of Common Murres. MATERIALS AND METHODS In 1993, commercial gill net fisheries occurred for summer sockeye salmon (Onchorhynchus nerka) in northern Puget Sound and for fall chum salmon (0. keta) in Hood Canal and central Puget Sound, Washington (Pierce et al. 1994). To evaluate various modified gill net designs, test fisheries were done in 1993 by Washington Sea Grant, and in 1993 and 1996 by Washington Sea Grant and Washington Department of Fish and Wildlife. Entangled seabirds were collected: (1) from commercial fisheries in 1993 from 1

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 599:239-251 (2018) - DOI: https://doi.org/10.3354/meps12624 Moult location and diet of auks in the North Sea inferred from coupled light-based and isotope-based geolocation Katie St. John Glew1,*, Sarah Wanless2, Michael P. Harris2, Francis Daunt2, Kjell Einar Erikstad3,4, Hallvard Strøm5, Clive N. Trueman1 1Ocean and Earth Science, University of Southampton, Waterfront Campus, Southampton SO143ZH, UK 2Centre for Ecology & Hydrology, Bush Estate, Penicuik EH26 0QB, UK 3Norwegian Institute for Nature Research, Fram Centre, 9296 Tromsø, Norway 4Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway 5Norwegian Polar Institute, Fram Centre, Postbox 6606 Langnes, 9296 Tromsø, Norway *Corresponding author: katie.stjohnglew@soton.ac.uk ABSTRACT: Many pelagic seabirds moult their feathers while at sea, which is an energetically costly behaviour. Mortality rates during moult can be high, so spatial and trophic ecology during this critical period is important for understanding demographic patterns. Unfortunately, individual foraging behaviours specifically linked to at-sea moulting are commonly unclear. This paper combines 2 different approaches to geolocation: data from bird-borne geolocation loggers and stable-isotope assignment using carbon and nitrogen isotope maps (isoscapes). Coupling 2 geolocation processes allows some uncertainties associated with isotope-based assignment to be constrained. We applied this approach to quantify species-specific foraging locations and individual trophic variability during feather regrowth in 3 sympatric auk populations breeding on the Isle of May, Scotland (common guillemot Uria aalge, razorbill Alca torda and Atlantic puffin Fratercula arctica). Inferred foraging areas during moult differed between species and feather types. Guillemots likely underwent moult within the southern North Sea, razorbills along the east coast of England and into the southern North Sea and puffins off the east coast of Scotland. Estimates of individual trophic position varied considerably within feather types (up to 1 trophic level difference between individuals), among feather types grown during different time periods and across the 3 species, with guillemots consistently foraging at higher trophic positions than razorbills and puffins. Used in combination, these methods better constrain foraging areas during moulting, and provide a technique to explore individual differences and flexibility in foraging strategy, which is valuable information for both seabird conservation and marine spatial planning. KEY WORDS: Isoscape · Trophic ecology · Foraging · Moult · Atlantic puffin · Common guillemot · Razorbill Full text in pdf format PreviousNextCite this article as: St John Glew K, Wanless S, Harris MP, Daunt F, Erikstad KE, Strøm H, Trueman CN (2018) Moult location and diet of auks in the North Sea inferred from coupled light-based and isotope-based geolocation. Mar Ecol Prog Ser 599:239-251. https://doi.org/10.3354/meps12624 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 599. Online publication date: July 12, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Geographical variation in two related seabird species, the razorbill (Alca torda) and common guillemot (Uria aalge), was investigated using sequence analysis of mitochondrial DNA (mtDNA) control regions. We determined the nucleotide sequence of the variable 5' segment of the control region in razorbills and common guillemots from breeding colonies across the Atlantic Ocean. The ecology and life history characteristics of razorbill and common guillemot are in many respects similar. They are both considered highly philopatric and have largely overlapping distributions in temperate and subarctic regions of the North Atlantic, yet the species were found to differ widely in the extent and spatial distribution of mtDNA variation. Moreover, the differences in genetic differentiation and diversity were in the opposite direction to that expected from a consideration of traditional classifications and current population sizes. Indices of genetic diversity were highest in razorbill and varied among colonies, as did genotype frequencies, suggestive of restrictions to gene flow. The distribution of genetic variation suggests that razorbills originated from a refugial population in the south-western Atlantic Ocean through sequential founder events and subsequent expansion in the east and north. In common guillemots, genetic diversity was low and there was a lack of geographical structure, consistent with a recent population bottleneck, expansion and gene flow. We suggest that the reduced level of genetic diversity and differentiation in the common guillemot is caused by an inherent propensity for repeated population bottlenecks and concomitantly unstable population structure related to their specialized feeding ecology.

The adaptive significance of avian egg shape in birds is poorly understood. The pyriform (pear‐like) shape of the Common Guillemot's Uria aalge egg has long been considered to be an adaptation to prevent eggs rolling off the bare cliff ledges on which this species breeds. Rolling was thought to be prevented either by the egg spinning like a top, which is not the case, or by rolling in an arc, which it does but with little influence on whether the egg will fall from a ledge. We therefore sought alternative explanations for the pyriform shape of the Common Guillemot's egg. This species breeds in extremely dense colonies, which makes their eggs vulnerable to mechanical damage from conspecifics, and to contamination by debris such as faeces and soil. We present evidence consistent with both these possible explanations. First, the pyriform shape of Common Guillemot eggs means that a higher proportion of the eggshell lies in contact with the substrate and this may minimize the effect of impacts. Resistance to impacts may be further enhanced because their eggshells are especially thick where they are in contact with the substrate. Secondly, Common Guillemot eggs are often heavily contaminated with faecal material and other debris during incubation. Most contamination is on the pointed end of the egg where it is in contact with the substrate; the pyriform shape thus keeps the blunt end of the egg, which has the highest porosity, relatively free of contamination, which in turn may facilitate both gas exchange during incubation and the hatching process, because the chick emerges from the blunt end of the egg.

Time-lapse photography was used to describe daily and seasonal trends in attendance by Common Guillemot Uria aalge at a colony in Shetland prior to the breeding season, including detection of nocturnal presence. A camera took a photo every 30 minutes from 30 January until 21 April 2015. A total of 3,435 photos were analysed, of which 3,232 photos allowed birds to either be accurately counted (2,552) or estimated (680) within a representative plot. High quality moonlit shots showed that large numbers of Common Guillemots were present ashore at Sumburgh throughout the night, while manipulated non-moonlight night photos revealed attendance at the colony, even when counting was not possible. Clear cycles of attendance at the colony were apparent with day-time peaks of 90–120 birds occurring on average every 7 days over the study period. Pre-breeding attendance is described, as is the nocturnal presence of Common Guillemots in the three months prior to breeding.

Following a supposed decrease in food availability during the breeding season as a result of a collapse in the Barents Sea capelin Mallotus villosus stock in 1986/87, it was hypothesized that there would be an increase in food competition and partitioning between the seabird species breeding in the region. A comparison of the diets collected from seven seabird species breeding on Horn0y in 1983 and 1989 showed that, despite a much lower capelin stock they actually caught a higher proportion of capelin in 1989, but fewer sandeels Ammodytes sp. It seems that the seabirds on Horn0y were more dependant on the sandeels than initially anticipated, and that sandeels have declined in abundance. We propose that the seabirds on Horn0y may also exploit a separate, late-spawning fjordic stock of capelin during the chick-rearing period. The median maximum diving depths attained by Common and Briinnich's Guillemots Uria aalge and U. lomvia were ca. 50 m, while Razorbills Alca torda, Puffins Fratercula arctica and Shags Phalacrocorax aristotelis reached 25-30 m (median). These depths reflected the distribution of prey more than the birds' diving abilities.

When species competing for the same resources coexist, some segregation in the way they utilize those resources is expected. However, little is known about how closely related sympatric breeding species segregate outside the breeding season. We investigated the annual segregation of three closely related seabirds (razorbill Alca torda , common guillemot Uria aalge and Brünnich’s guillemot U . lomvia ) breeding at the same colony in Southwest Greenland. By combining GPS and geolocation (GLS) tracking with dive depth and stable isotope analyses, we compared spatial and dietary resource partitioning. During the breeding season, we found the three species to segregate in diet and/or dive depth, but less in foraging area. During both the post-breeding and pre-breeding periods, the three species had an increased overlap in diet, but were dispersed over a larger spatial scale. Dive depths were similar across the annual cycle, suggesting morphological adaptations fixed by evolution. Prey choice, on the other hand, seemed much more flexible and therefore more likely to be affected by the immediate presence of potential competitors.

Understanding how seabirds use the marine environment is key for marine spatial planning, and maps of their marine distributions derived from transect-based surveys and from tracking of individual bird’s movements are increasingly available for the same geographic areas. Although the value of integrating these different datasets is well recognised, few studies have undertaken quantitative comparisons of the resulting distributions. Here we take advantage of four existing distribution maps and conduct a quantitative comparison for four seabird species (black-legged kittiwake Rissa tridactyla; European shag Phalacrocorax aristotelis; common guillemot Uria aalge; and razorbill Alca torda). We quantify the amount of overlap and agreement in the location of high use areas identified from either tracking or transect samples and use Bhattacharyya’s Affinity to quantify levels of similarity in the general distribution patterns. Despite multiple differences in the properties of the datasets, there was a far greater degree of overlap than would be expected by chance, except when adopting the most constrained definition of high use. Distance to the nearest conspecific colony appeared to be an important driver of the degree of similarity. Agreed areas of highest use tended to occur close to colonies and, with increasing distance from colonies, similarity between datasets declined and/or there was similarity in respect of their being relatively low usage. Interpreting reasons for agreement between data sources in some areas and not others was limited by an inability to control for the multiple potential sources of differences from both the sampling and modelling processes of the underlying datasets. Nevertheless, our quantitative comparative approach provides a valuable tool to quantify the degree to which an area’s importance is corroborated across multiple datasets, and therefore confidence that an important area has been correctly identified. This can help prioritise where the implementation of conservation measures should be targeted and identify where greatest scrutiny is required of the potential adverse environmental effects of any planned anthropogenic activities.

Incidental mortality (bycatch) in fisheries represents a threat to marine vertebrates. Research has predominantly focussed on bycatch in longline fisheries, but bycatch from gillnet fisheries is of increasing concern. To address this concern, we combined comprehensive biologging data sets and multiple sources of fishing effort data to assess the spatial overlap of 3 diving seabird species during the breeding season (common guillemotUria aalge, razorbillAlca tordaand European shagPhalacrocorax aristotelis) with UK gillnet fisheries. Species distribution models based on birds’ diving behaviour identified areas of elevated bycatch risk where high levels of diving activity and fishing effort coincided. In addition, we identified times of day and water depths where diving activity, and hence bycatch risk, may be concentrated. Bycatch risk hotspots for all 3 species were identified along the north-east coast of England. Risk hotspots were also identified along the Pembrokeshire coast for both auk species and along the Cornish coast for shag. Lack of fishing effort data for smaller vessels made it difficult to assess seabird-fishery overlap in Scottish waters. Across species, diving activity was lower at night. For razorbill and guillemot, dive depth tended to increase at sunrise and decrease after sunset. For shag, dive depth showed no diel pattern but was associated with water depth. Our findings should assist in targeting spatio-temporal measures and designing deterrent devices to reduce bycatch. However, scarcity of data on the behaviour of gillnet fishers at comparable spatio-temporal resolution as seabird movement data remains a constraint to fully understanding seabird-fisheries interactions.

ABSTRACTCapsule: Foraging behaviour in the Razorbill Alca torda during breeding was similar to that found elsewhere, aside from dive shape.Aims: To investigate the foraging behaviour of Razorbills during the breeding season at the largest colony in the central Baltic Sea.Methods: A combination of global positioning system (GPS) and time-depth recorder (TDR) devices were used on Razorbills breeding on the island of Stora Karlsö, Baltic Sea, during the chick-rearing period.Results: Five GPS tracks and nine TDR logs were retrieved from 12 Razorbills, and 7399 dives were analysed. Razorbills foraged south and southwest of the colony. Maximum and mean (±sd) foraging range from the colony was 72.7 km and 13.1 ± 13.5 km, respectively. Mean dive depth (15.3 ± 2.4 m) and duration (53.1 ± 8.5 s) were similar to those of a more southern Baltic Sea Razorbill colony. Dive depth had a bimodal distribution, with 70% of dives deeper than 10 m and 30% shallower than 10 m. There was a clear diel foraging pattern with 89% of dives occurring during daytime and a higher proportion of shallow dives at night. Unexpectedly, dives were primarily U-shaped. The Razorbills spent 31% of their overall time activity budget flying or diving.Conclusion: Aside from dive shape, foraging behaviour was consistent with that reported at other colonies of Razorbills. Inconsistency in dive shape may be due to a bimodal foraging strategy, local prey behaviour or competition with the Common Guillemot Uria aalge.