The Pigeon Guillemot (Cepphus grylle columba), a member of the Auk family, was studied by the writer at Mandarte Island, British Columbia, in the summers of 1959 and 1960. Banding and the keeping of nest records had commenced at this colony in 1957, so that on many questions four years' data are available. Colour-banded adults and banded immatures of known age, were basic to the study. Behaviour, and social structure of the colony, are described on the basis of these banded birds. Incubation temperatures and rhythm were investigated with thermocouples. Feeding, growth of the chick in weight from hatching to nest departure, and the advent of thermoregulation, are treated. Placed in an appendix are statistics on egg and chick mortality up to the point of nest departure. / Science, Faculty of / Zoology, Department of / Graduate

Following a large kill of Black Guillemots in the Esso Bernicia oil spill in Shetland, this study was initiated to determine the population size and distribution of the species at different times of year and to investigate its ecology. The results will enable oil spill contingency plans to be made for this species and provide a base-line against which future work can be compared. This is the first major study of Black Guillemots in the UK. There were large diurnal and seasonal fluctuations in colony attendance patterns which were investigated in relation to various factors. Reliable census techniques were devised and suitable stretches of coastline were established as monitoring units. Black Guillemots rarely foraged in water more than 40-50 m deep, and seldom moved more than 3 km from the nest during the breeding season. The proximity of suitable breeding sites to shallow water feeding grounds accounted for the fairly regular breeding dispersion. On islands with mammalian predators only nest sites in inaccessible cliffs were used. In many areas breeding numbers were limited by nest site availability. The distribution at other times of year was more irregular. After breeding adults congregated in traditional moulting areas where they became flightless for 4-5 weeks. These flocks of up to c.600 adults constitute vulnerable "hot spots" at which the effect of oil pollution would be most severe. In winter there was some movement away from exposed coasts, resulting in concentrations in more sheltered, inshore waters. A wide range of fish and invertebrates were eaten by adults, largely reflecting the diversity of inshore benthic communities. There appears to be a greater dependence on invertebrates during the winter months, when fish are scarcer. Chicks were fed almost exclusively on fish: their diet composition was determined primarily by local availability, although some adults specialised on particular species. When large gadoid fish became available in late summer adults were able to provide more energy per feed and consequently chicks were heavier at fledging. Breeding parameters were quantified and analysed in relation to various factors. Breeding success and chick growth compared very favourably with results of studies elsewhere, indicating that conditions for breeding were good for Black Guillemots in Shetland. In a year of more favourable environmental conditions a greater proportion of inexperienced birds were able to reach the condition threshold for breeding. These birds tended to lay single-egg clutches, in sub-optimal sites at which egg predation was heavy and breeding success low. Some pairs of Arctic Skuas benefit ed considerably from kleptoparasitism of chick feeds at larger colonies, but Black Guillemot breeding success was not affected and chick growth was only depressed at high rates of piracy. Overall, conditions in Shetland are favourable throughout the year for this seabird, whose ecology is moulded to the exploitation of an inshore feeding niche.

Since 1974 a population study of Black Guillemots has been conducted on Flatey Island, NW Iceland. The main aspects are summarized below. Population numbers and distribution. The population has been censused several years, also those of 20 islets near Flatey. Information was collected on past status. Great changes have occurred since turn of the century. Last major change began in 1967; the population started increasing of such a scale that it can only have resulted from massive immigration. These changes are thought to be due to rats and Mink. Attendance and population structure. Data was gathered on timing of spring return to nesting areas, status of attending birds, sex ratio, area and nest-site fidelity, pair-bond maintenance, and post-breeding departure. Special attention has been given to the problem of censusing birds attending nesting areas. Breeding biology. Breeding biology variables were quantified and studied on a seasonal basisj;timing of laying, clutch size, interval between eggs, egg size, reproductive output, lengths of incubation and nestling periods. Supernormal clutch and brood experiments were conducted. I looked at length of replacement time of lost clutches, factors influencing timing of laying, its effect and that of clutch and egg size on breeding performance. Egg and chick losses were analyzed. Many interesting population phenomena seem to have been associated with the unusually rapid population increase. Feeding ecology. Analyses were made of prey taken, feeding rhythm and areas, and factors influencing feeding rate and prey selection. Some information was collected on share of the sexes in feeding chicks, and kleptoparasitism. Study was made of chick growth, fledging condition and postfledging survival. Population dynamics. About 3300 birds were ringed, providing basis for determining age at maturity, adult survival, and mortality. Pre-breeding survival was calculated using data from ringing schemes. A population model was constructed for the population, showing magnitude of immigration. Ringing provided data on dispersal.

<p>Observations of feeding behaviour of common guillemots, <em>Uria aalge</em>, in June 2002 at the island Stora Karlsö in the Baltic Sea proper, and measurements of morphology and energy density in the prey fish sprat, <em>Sprattus sprattus</em>, showed that fish delivered to chicks at present are shorter and weigh less than in the 1970s. Long lasting attending periods and a feeding rate of 4.6 feeds per day indicate that parents are feeding their chicks at a maximum rate. Because of a decline in the energy density in sprat (22.4 kJg^-1 dry weight) the daily energy intake of common guillemot chicks have declined noticeably. This could probably explain the observed decrease in fledging body weight of chicks through the 1990s. Baltic common guillemots do not seem to be able to select more energy-dense prey sizes or to switch to other prey species.</p>

Observations of feeding behaviour of common guillemots, Uria aalge, in June 2002 at the island Stora Karlsö in the Baltic Sea proper, and measurements of morphology and energy density in the prey fish sprat, Sprattus sprattus, showed that fish delivered to chicks at present are shorter and weigh less than in the 1970s. Long lasting attending periods and a feeding rate of 4.6 feeds per day indicate that parents are feeding their chicks at a maximum rate. Because of a decline in the energy density in sprat (22.4 kJg-1 dry weight) the daily energy intake of common guillemot chicks have declined noticeably. This could probably explain the observed decrease in fledging body weight of chicks through the 1990s. Baltic common guillemots do not seem to be able to select more energy-dense prey sizes or to switch to other prey species.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 63-68). Description: viii, 68 leaves : map ; 29 cm. / The ability of the Pigeon Guillemot Cepphus columba to rear an additional chick was tested by manipulating clutch sizes. The effect of the manipulations on growth, and hatching, fledging, and egg success was measured in chicks from experimental, natural, and control nests. No significant differences were observed between the nest types. Data from 1983, 1984, 1985, and 1989 were analyzed for potential differences in reproductive success of one and two egg clutches. The ratio of one to two eggs was significantly higher in 1985 and 1989. Hatching and fledging success was significantly higher for two egg clutches in 1985 and 1989. No significant differences were observed for egg success. Egg volume was significantly greater in two egg clutches in 1983 and 1984. Egg volume was correlated with fledging but not with hatching success.

The pigeon guillemot (Cepphus columba) population in Prince William Sound has failed to recover from declines that occurred both before and after the Exxon Valdez Oil Spill (EVOS). Post-spill studies of pigeon guillemot breeding biology have identified three potential factors limiting recovery: (1) predation on eggs and nestlings; (2) declines in the proportion of high-lipid, schooling forage fish (sand lance [Ammodytes hexapterus], herring [Clupea pallasi], and capelin [Mallotus villosus]) in the diet; and (3) continued exposure to residual oil from the spill. This laboratory study with captive-reared pigeon guillemots at the Alaska SeaLife Center investigated two aspects of the species' biology that are relevant to restoration in the aftermath of EVOS. First, we investigated the role of dietary factors (prey type, quantity of food consumed, dietary fat content, and energy intake rate) in limiting the growth, development, survival, and fledging condition of nestling pigeon guillemots. The objective was to understand how changes in prey availability and prey quality might affect pigeon guillemot productivity. Second, we fed nestlings sublethal doses of weathered Prudhoe Bay crude oil (PBCO) and then measured several potential biomarkers of effects from this pollutant. These dose-response experiments were designed to (1) better understand the impact on nestling guillemots of petroleum hydrocarbons in food, (2) calibrate existing and potential biomarkers of exposure to PBCO in pigeon guillemots in a controlled, laboratory setting, and (3) develop better nondestructive biomarkers of exposure to PBCO in pigeon guillemots in particular, and seabirds in general. Results of feeding experiments indicated that most variation in nestling growth rates could be explained by variation in daily energy intake. The type of forage fish consumed, the lipid or protein content of the forage fish, and even the quantity of food consumed daily did not have as strong an effect on nestling guillemot growth as did daily energy intake. The metabolic efficiency and growth performance of nestling guillemots was not enhanced on high-lipid diets, contrary to results with nestlings of some other seabird species. Instead, structural growth (wing length) in nestling guillemots was somewhat stunted on high-lipid diets. These attributes of guillemot nutritional requirements are associated with the guillemots' nearshore foraging niche and high food provisioning rates to nestlings. The average lipid content of sand lance, juvenile herring, and capelin may represent the optimal dietary lipid content for nestling pigeon guillemots. This study supports the hypothesis that guillemot productivity is limited by the availability of these forage fishes through effects on energy provisioning rates to nestling guillemots. Consequently, recovery of pigeon guillemot populations injured by EVOS is likely linked to recovery of these key forage fish stocks. Results of the oil-dosing experiments indicated that nestling guillemots are resistant to small doses of weathered PBCO in their food. No nestlings died or suffered noticeable health effects following dosing. The high dose in this study (0.5 ml kg����� day�����) was sufficient to induce hepatic cytochrome P450A1 (a liver enzyme indicative of contaminant exposure), but growth rate, fledging mass, and blood chemistry were largely unaffected. None of the 12 plasma or hematological markers examined responded in a dose-dependent manner to ingestion of weathered PBCO, except lactate dehydrogenase (LDH). Although baseline stress hormone (corticosterone) levels were not different between oil-dosed and control nestlings, a standardized acute stress protocol revealed that corticosterone was more elevated during stress for oiled nestlings compared to controls. Although we were not successful in identifying a noninvasive biomarker (e.g., growth) or a blood biomarker (e.g., haptoglobin) of crude oil exposure in nestlings, we were able to confirm that levels of hepatic cytochrome P4SO1AI and corticosterone during stress were elevated by the sublethal doses administered during our experiments. Based on this and other studies, it is unlikely that the failure of pigeon guillemots to recover from EVOS is due to effects on nestling health of residual oil in food. / Graduation date: 2003

En Arctique, la productivité marine comprend deux floraisons successives de producteurs primaires, les algues deglace et le phytoplancton, qui sont étroitement liée à la phénologie de la glace de mer. Ceux-ci constituent la base du réseau trophique et fournissent l’énergie transférée vers les niveaux trophiques supérieurs. Ainsi, tout changement affectant la banquise arctique aura de fortes implications sur la phénologie des producteurs primaires, et affectera par conséquent tous les autres niveaux trophiques. Des études antérieures ont démontré le potentiel des Isoprénoides Hautement Ramifiés (HBIs) pour quantifier les contributions relatives des deux pools de producteurs primaires vers les niveaux trophiques supérieurs. Ici, nous combinons les HBIs avec les isotopes stables afin (i) d’évaluer si et à quel point les oiseaux marins arctiques dépendent de la glace de mer, et (ii) de déterminer si les variations de glace affectent leur écologie alimentaire et leur performance reproductive. L’étude cible deux espèces abondantes en Arctique présentant des écologies distinctes: le guillemot de Brünnich (Uria lomvia) et le fulmar boréal (Fulmarus glacialis). Pour chaque espèce, 60 œufs ont été récoltés sur l’île du Prince Leopold (Arctique canadien) pendant des années aux conditions de glace fortement contrastées (2010-2013). Les distributions en HBIs et les compositions isotopiques (carbone et azote) et énergétiques ont été analysées pour chaque œuf. Les résultats montrent que la présence de glace est bénéfique pour la performance reproductive des guillemots, avec des œufs plus gros et plus énergétiques pondus durant les années plus englacées. Les guillemots sont étroitement liés à la banquise et dépendent fortement de proies associées à la glace. Au contraire, les fulmars ne présentent aucune association claire aux communautés sympagiques, et les variations du couvert de glace n’affectent ni leur écologie alimentaire ni leur performance reproductive. De fait, les guillemots semblent plus vulnérables face aux changements climatiques à venir, alors que des espèces plus résilientes comme les fulmars pourraient en tirer avantage. Dans l’ensemble, notre étude souligne l’importance des approches multi-biomarqueurs afin de mieux appréhender l’importance des ressources sympagiques pour les prédateurs supérieurs au sein d’écosystèmes marins arctiques en pleine mutation. / In the Arctic, sea ice sets the clock for marine productivity. This includes two consecutive pulses of primary producers, sea-ice algae and phytoplankton, that constitute the basis of marine food webs and provide the energy transferred to higher trophic levels. As such, any change affecting Arctic sea-ice will have strong implications on the phenology of primary producers, and cascading effects on all other trophic levels. Previous studies demonstrated the potential of Highly Branched Isoprenoid biomarkers (HBIs) to quantify the relative contributions of the two pools of primary producers to higher trophic levels. Here, we combined HBIs with stable isotopesto (i) evaluate if and how much arctic seabird rely on sea ice, and (ii) determine if changes in sea ice affect their feeding ecology and reproductive performance. We focused on two Arctic species exhibiting contrasting ecologies: the thick-billed murre (Uria lomvia) and the northern fulmar (Fulmarus glacialis). For each species, 60 eggs were collected on Prince Leopold Island (Canadian Arctic) during years of highly contrasting ice conditions (2010-2013). Eggs were analysed for HBI distributions, isotopic (carbon and nitrogen) and energetic compositions. Results showed that murres were closely linked to sea ice and heavily relied on ice-associated prey. Sea ice presence was beneficial for murres’ reproductive performance, with larger and more energetic eggs laid during icier years. In contrast, fulmars did not exhibit a clear association with sympagic communities. Even large changes in sea ice did not seem to affect their feeding ecology or their reproductive performance. Murres therefore appear more vulnerable to changes and may become the losers of future climate shifts in the Arctic, while more resilient species such as fulmars might make the most of the situation. Overall, our study emphasises the importance of combining different biomarkers to better understand the importance of sympagic resources for top predators within changing Arctic marine ecosystems

This study attempted to explain an apparent inverse relationship between pack ice proximity and breeding success of Black Guillemots (Cepphus grylle) on Cooper Island, a barrier island in the western Beaufort Sea near Barrow, AK. I elucidated the first linear relationship between energy density and body size for the elusive Arctic Cod (Boreogadus saida). I discovered and ground-truthed the existence of previously unknown guillemot foraging habitat on small 50 m2 ice floes distant from the pack ice. I developed new daily metrics for quantifying the provisioning to linear (8 d – 18 d) and Post-Linear (19 d – fledge) chicks. I found daily consensus between Linear and Post-Linear chicks about the level of provisioning at the colony. Finally, I explained those daily changes with significant correlations with wind speed and direction. / October 2007

This study attempted to explain an apparent inverse relationship between pack ice proximity and breeding success of Black Guillemots (Cepphus grylle) on Cooper Island, a barrier island in the western Beaufort Sea near Barrow, AK. I elucidated the first linear relationship between energy density and body size for the elusive Arctic Cod (Boreogadus saida). I discovered and ground-truthed the existence of previously unknown guillemot foraging habitat on small 50 m2 ice floes distant from the pack ice. I developed new daily metrics for quantifying the provisioning to linear (8 d – 18 d) and Post-Linear (19 d – fledge) chicks. I found daily consensus between Linear and Post-Linear chicks about the level of provisioning at the colony. Finally, I explained those daily changes with significant correlations with wind speed and direction.