Auk Chicks Research Articles

Meso-scale variations in diet composition of little auk chicks in north-west Spitsbergen

Colonial seabirds from neighbouring breeding aggregations may share foraging grounds or utilize different areas in order to decrease the competition over food resources. In our study, we present th...

Parent-offspring interactions in a long-lived seabird, the Little Auk (Alle alle): begging and provisioning under simulated stress

Long-lived seabirds are good models to study the mechanisms that mediate the parent–offspring interactions. Contrary to studies under natural conditions, experimental manipulations allow us to assess the birds’ reactions in a short time period. We used the stress hormone corticosterone as an independent experimental factor to simulate the stress reaction, to examine changes in the behaviour of Little Auk chicks and parent birds. In the first experiment, we hypothesised that after enhancement of the corticosterone level Little Auk (Alle alle) chicks intensify their begging performance and attain a higher pre-fledging body mass than the control chicks. In the second experiment, we hypothesized that parent Little Auks with an increased corticosterone level feed their chicks less frequently and spend less time at the colony than their untreated partners and the control birds. We also expected that chicks with one parent implanted with corticosterone fledge later and with a lower body mass than chicks of two untreated parents. The obtained results supported the above hypotheses. We demonstrated that modification of begging performance in Little Auks constitutes an adaptive mechanism that guards against the decrease in the chicks’ body condition during stressful periods. Even though the provisioning rate in Little Auks can be regulated according to the chick’s needs (expressed by the intensity of the begging display), it appears that adult birds regulate their provisioning strategy primarily according to their body state. The results suggest that parent Little Auks under stressful conditions will decrease their parental effort and redirect the available energy towards self-maintenance. The study provides novel insights into the behaviour of long-lived alcids using an experimental approach on free-living birds.

Supplementary diet components of little auk chicks in two contrasting regions on the West Spitsbergen coast.

The complete diet composition structure of the most numerous planktivorous sea bird, little auk (Alle alle), in the European Arctic, is still not fully recognized. Although regular constituents of little auk chick diets, the copepods, Calanus glacialis and C. finmarchicus have been previously relatively well described, more taxa were frequent ingredients of the bird’s meals. Therefore, the role of the little auks supplementary diet components (SDCs) at two colonies in the Svalbard Archipelago, Hornsund and Magdalenefjorden, in 2007–2009, is a main subject of this comparative study. Because the SDCs often consisted of scarce but large zooplankters, this investigation was focused on biomass as a proxy of the SDCs’ energy input. Although the total biomass of the food delivered to chicks in both colonies was similar, in Magdalenefjorden, the proportion of SDCs was twice that found in Hornsund. The main SDCs in Hornsund were Decapoda larvae (with predominating Pagurus pubescens) and Thysanoessa inermis, whereas the main SDCs in Magdalenefjorden were C. hyperboreus and Apherusa glacialis. Previous investigations, which indicated lipid richness of SDCs, together with our ecological results from the colonies, suggest that this category might play a compensatory role in little auk chick diets. The ability to forage on diverse taxa may help the birds to adapt to ongoing Arctic ecosystem changes.

Fledging success of little auks in the high Arctic: do provisioning rates and the quality of foraging grounds matter?

Long-lived birds often face a dilemma between self-maintenance and reproduction. In order to maximize fitness, some seabird parents alternate short trips to collect food for offspring with long trips for self-feeding (bimodal foraging strategy). In this study, we examined whether temporal and spatial variation in the quality of foraging grounds affect provisioning and fledging success of a long-lived, bimodal forager, the little auk (Alle alle), the most abundant seabird species in the Arctic ecosystem. We predicted that an increase in sea surface temperature (SST), with an associated decrease in the preferred Arctic zooplankton prey, would increase foraging trip durations, decrease chick provisioning rates and decrease chick fledging success. Chick provisioning and survival were observed during three consecutive years (2008–2010) at two colonies with variable foraging conditions in Spitsbergen: Isfjorden and Magdalenefjorden. We found that a change in SST (range 1.6–5.4 °C) did not influence trip durations or provisioning rates. SST was, however, negatively correlated with the number of prey items delivered to a chick. Furthermore, provisioning rates did not influence chick’s probability to fledge; instead, SST was also negatively correlated with fledging probability. This was likely related to the prey availability and quality in the little auk’s foraging grounds. Our findings suggest that predicted warmer climate in the Arctic will negatively influence the ability of parents to provide their chicks, and consequently, the fledging prospects of little auk chicks.

Interannual changes in zooplankton on the West Spitsbergen Shelf in relation to hydrography and their consequences for the diet of planktivorous seabirds

AbstractKwasniewski, S., Gluchowska, M., Walkusz, W., Karnovsky, N. J., Jakubas, D., Wojczulanis-Jakubas, K., Harding, A. M. A., Goszczko, I., Cisek, M., Beszczynska-Möller, A., Walczowski, W., Weslawski, J. M., and Stempniewicz, L. 2012. Interannual changes in zooplankton on the West Spitsbergen Shelf in relation to hydrography and their consequences for the diet of planktivorous seabirds. – ICES Journal of Marine Science, 69: 890–901. The purpose of the work was to determine how atmospheric and oceanic processes (the North Atlantic Oscillation (NAO) and the Arctic Ocean Oscillation (AOO)) influence hydrography and zooplankton on the West Spitsbergen Shelf (WSS), and the impacts of the processes on chick meals of zooplanktivorous little auks Alle alle. There were distinct Atlantic and Arctic oceanographic domains on the shelf resulting from the presence of the West Spitsbergen Current and the Sørkapp Current, which contain different proportions of Calanus finmarchicus and C. glacialis. The abundance of warm- and cold-water species varied as a result of an interplay between processes in the atmosphere and ocean. In the Arctic domain, on which the study focused, the NAO impacted oceanography, zooplankton, and consequently little auk chick meals, with time-lags of 4–7 years. The diet of little auk chicks was more energy-rich when C. glacialis stage 5 in the Arctic community were more easily available. To date, the changes in zooplankton abundance on the WSS have not posed a threat to the ability of little auks to feed their chicks lipid-rich Arctic copepods.

The impact of different hydrographic conditions and zooplankton communities on provisioning Little Auks along the West coast of Spitsbergen

Composition and abundance of zooplankton were studied simultaneously with feeding ecology of planktivorous Little Auks ( Alle alle) in two different sea shelf areas of West Spitsbergen, Norway, in summer 2007. Zooplankton was collected adjacent to bird colonies in Magdalenefjorden (influenced by Atlantic West Spitsbergen Current) and Hornsund (dominated by the Arctic Sørkapp Current). In spite of different hydrological situations, the abundance of prey preferred by Little Auks, Arctic Calanus glacialis copepodids stage V, among zooplankton was similar in both localities. However, there was much more of Atlantic Calanus finmarchicus on the shelf outside Magdalenefjorden compared to Hornsund, resulting in different abundance ratios of Arctic to Atlantic copepods in the two areas (1:14 and 1:1, respectively). Even greater differences between the two areas occurred in the ratio of C. glacialis CV to other zooplankters, amounting to 1:40 in Magdalenefjorden and 1:6 in Hornsund. In both Little Auk colonies food brought by parents to their chicks contained mainly C. glacialis CV, albeit the proportion of this copepod in meals was significantly higher in Hornsund. Meals delivered to Little Auk chicks in Hornsund had also higher zooplankton numbers, biomass and energy content. In Magdalenefjorden, on the other hand, a higher number of feedings and longer duration of foraging trips were recorded. These differences became more apparent with increasing energy requirements of the fast growing nestlings. This was probably a consequence of lower relative abundance of the Little Auks’ preferred prey in the sea adjacent to Magdalenefjorden colony. It seems that searching for the preferred food items, such as C. glacialis, among abundant but less favored C. finmarchicus, may require more time and energy demanding foraging behavior. As a consequence, foraging effort of the Little Auk parents from Magdalenefjorden was higher, and feeding efficiency lower, than those of birds from Hornsund. Increasing influx of warm Atlantic waters that bring boreal zooplankton to the Arctic Seas may have negative impacts on Little Auks’ time and energy budgets and eventually on their breeding success and range of breeding distribution.

Stable isotopic determinations of trophic relationships of great auks.

Stable isotopic ratios of animal tissues are related to those of their foods and can be used in palaeoecological reconstructions, including those of extinct animals. Nitrogen isotopic analyses of marine organisms from coastal Newfoundland and Georges Bank were used to construct a model predicting collagen δ15N values for seabirds feeding at various trophic levels (TL). This model was tested by measuring bone collagen δ15N values of extant alcids from the northwest Atlantic and high Arctic. Isotopic analysis of bone collagen of the extinct great auk (Pinguinus impennis), the last flightless seabird in the northern hemisphere, indicate that this species occupied a trophic continuum from TL3 (crustacean diets) to TL5 (diets of piscivorous fish). We suggest that (a) great auk chicks and juveniles occupied lower trophic levels and probably consumed euphausiids, and (b) great auks fed offspring via regurgitation, as do dovekies (Alle alle), the only extant fully planktivorous alcid in the Atlantic, and unrelated penguins of the southern hemisphere.

On the importance of fat reserves for the little auk (Alle alle) chicks.

The pattern of fat deposition and inter-year variation in the amount of deposited fat, lean dry mass (LDM) and water were studied in the chicks of little auk (Alle alle), an arctic alcid, at Spitsbergen in the 1984, 1986 and 1987 breeding seasons. The lipid index (lipid mass/LDM) rose from 0.29 at hatching to about 0.70 at the age of maximum body mass attained in the nest, the highest yet recorded for seabirds except procellariiforms. Just before fledging the index dropped to 0.38. Fat mass in 1984 chicks and also fresh body mass of older 1984 chicks was significantly lower than in the other two seasons, but there were no statistical year-to-year differences in LDM's of chicks. The amount of fat in chicks was significantly correlated with certain weather parameters. Fasting capability (FC) of the chicks (the time that chicks could survive when using only their lipid stores) was calculated from fat mass and previous data on metabolic rates of chicks. The FC's of all 108 chicks collected in three seasons were greater than maximum interval between two consecutive feeds to chicks reported in the study colony. Also the estimated fat reserves of 99.7% of chicks weighed in 1984 were sufficient to support them for longer than the maximum recorded intervals between feeds. In relation to death by starvation, little auk chicks, at least up to the age of maximum body mass, have a substantial surplus of fat. This is contrary to the hypothesis that fat depots in seabird chicks assist survival during the periodic fasts resulting from unpredictable feeding conditions.

The Influence of Weather Conditions on Growth of Little Auk Alle alle Chicks

The influence of weather variables (visibility, windspeed, temperature, precipitation, cloudiness, and duration of sunshine) on growth of Little Auk chicks was analysed by means of stepwise multiple regression. We found a statistically significant negative influence of precipitation on chicks 1-5 d old, a negative impact of wind, and a positive effect of visibility on the growth of chicks older than 5 d. Based on a day-to-day analysis we found five days throughout the chicks' development in which their growth was influenced by visibility or precipitation. Characteristically, we detected the influence of these variables on chicks' growth in times of changing weather conditions. Air temperatures measured in three nests were stable and close to ambient temperature. Only in one nest was the temperature significantly correlated with ambient temperature. We conclude that some weather variables clearly influenced changes in body weight of Little Auk chicks, although their effect on postnatal development was weak.

THE FLEDGING OF THE GUILLEMOT URIA AALGE WITH NOTES ON THE RAZORBILL ALCA TORDA

SummaryThe chicks of the cliff nesting auks go to sea when only one‐third the weight of the adults and before the flight‐feathers are fully grown. Sea‐going occurs in the evening (except in the high Arctic) and the advantages and disadvantages of this timing are discussed.In the Guillemot, the behaviour which occurs on the ledges before the first‐flight consists of ritualized intention movements, serving to synchronize the behaviour of parent and chick so that when the latter jumps from the ledge the parent follows it.The “water‐call” is made by all chicks when they arrive on the water (many of them make it on the ledges just before flighting). It serves to direct the adult to the chick.A parent and chick swimming out to sea may receive mock attacks from adults unaccompanied by chicks on the water below the cliffs. These birds direct their activities mainly to chicks whose parents have not joined them on the water, but do not adopt them and they ultimately perish.High winds and rough seas depress fledging activity. Low temperatures and rain seem to have no comparable effect. The number of chicks whose parents do not join them on the water is proportionately higher on rough, windy evenings.The fledging of the Razorbill follows a very similar course to that of the Guillemot.Predation, mainly by gulls, of auk chicks at the time of fledging may be high, though fewer chicks perish as a result of predation alone than as a result of desertion by their parents.