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HORNSUND LITTLE AUK EXPEDITION 2002
FIELDWORK REPORT

ANN HARDING and TOM VAN PELT
AGLIONBY@YAHOO.COM   THOMAS_VAN_PELT@USGS.GOV

INTRODUCTION

We traveled to Hornsund in July and August 2002 to work on the breeding, feeding, and behavioural ecology of Little Auks (Alle alle). We sampled chick diets directly; adult diets indirectly; and measured a range of feeding ecology parameters to be merged with an ongoing study of Little Auk foraging ecology (see Background below). Additional independent field work focused on sex differences in parental behaviour and provisioning during the chick rearing and fledging period. The Expedition was based at the Polish Polar Station at Hornsund, Spitsbergen, on the archipelago of Svalbard (Figure 1), and was logistically supported by the Polish Academy of Sciences (Polska Akademia Nauk, PAN), with additional funding support from the Atlantic Seabird Group, the Gino Watkins Memorial Fund, the Augustine Courtauld Trust, and Alaska Pacific University.

BACKGROUND

The first international Little Auk Expedition to Hornsund took place in 2001, led by Jan Marcin Weslawski, from the Institute of Oceanology, PAN, Sopot, Poland. Team members were Nina Karnovsky (USA), Ph.D. student, University of California, Irvine; Fridtjof Mehlum (Norway), Zoological Museum, University of Oslo; Lech Illiszko (Poland), University of Gdansk; and Ann Harding (UK), Alaska Science Center, U.S. Geological Survey.
The primary aim of the study was to examine how the foraging behaviour of Little Auks is influenced by heterogeneous water masses surrounding the colony. Given that plankton populations closely track changes in ocean temperatures, plankton–feeding Little Auk populations are likely to be affected by changing climate and ocean currents. The colony at Hornsund is adjacent to an important confluence of Atlantic and Arctic Ocean currents, and therefore presents an ideal situation to investigate Little Auk feeding ecology and foraging activity in the context of variable oceanographic conditions. Colony-based parameters of feeding and breeding ecology (breeding success, chronology, chick growth, chick diet, feeding rates) were measured, concurrent with at-sea work including surveys to determine the distribution of foraging Little Auks, and zooplankton net tows, CTD casts, and hydroacoustic surveys to characterize the water masses.
The Atlantic section of the Arctic is currently undergoing large-scale changes in the distribution of water masses, and Little Auks may be forced to forage in areas with sub-optimal conditions if the pattern of Atlantic and Arctic water flow shifts. Insights gained from study at Hornsund will allow more complete understanding and prediction about how Little Auk populations may be influenced by changing ocean conditions.

2002 FIELDWORK

Fieldwork was conducted between 7 July and 24 August 2002, and was based at the Little Auk colonies at Ariekammen (77°03'N, 15°10'E), 1 km north of the Polish Polar Station at Hornsund. Zooplankton net tows, CTD casts, and hydroacoustic surveys to characterise the marine habitat were conducted during early chick rearing (22-26 July) by the PAN R/V Oceania. Nest sites were located during the end of the incubation period (8-11 July), and active sites were marked with a numbered wooden stake. To assess breeding chronology, 24 nests were checked every 1-3 days until hatch, and daily during the fledging period. Median chick hatch date (16 July; n=17 chicks) was used as a measure of annual timing of breeding. Fledging began on 6 August, and nearly all chicks had departed by 15 August. Median fledging date was 10 August (n=15 chicks).

Tom Van Pelt with adult little auk caught in mist net

CHICK DIET SAMPLES

Chick diet samples were collected from breeding adults returning to the colony with food for their chick; all captured adults were released without harm ca. 5 minutes post-capture. Diet samples were collected during early (n = 42 chick meals, 22-25 July), middle (n = 20chick meals, 2-5 August) and late (n = 21 chick meals, 10-11 August) chick rearing. A large number of meal loads were collected during early chick-rearing for species identification, and captures during this period were timed to overlap with the oceanographic sampling period of the Oceania. Birds were caught either by mist net or a long-handled hand net. We used the hand net to catch targeted individuals standing on rocks in the colony and the mist net to catch birds in flight departing from or arriving at the colony. Complete chick meals were gently scooped out of the gular pouch, and preserved for later analyses (see photos).

Before and after photos demonstrating
collection of zooplankton chick meal from gular pouch


Samples collected during each of the three catching periods were randomly allocated to either diet composition or stable isotope analyses (Table 1). Chick diet samples collected for diet composition analysis by the Institute of Oceanology, Sopot, Poland, were preserved in 5% formalin and stored in hard plastic pots to prevent damage to the individual prey items. Diet samples collected for stable isotope analysis by Keith Hobson at the Canadian Wildlife Service were preserved in 70% ethanol and stored in whirlpak bags or hard plastic pots.
Collaborating researchers aboard the PAN R/V Oceania (Wojtek Walkusz and Kasia Dmoch, cruise leader Josef Wiktor) collected voucher samples of the most common zooplankton species occurring in both the Atlantic and Arctic waters; these specimens will provide benchmark prey values for more powerful interpretation of the stable isotope analyses.

TABLE 1. Number of chick meals collected for diet composition and stable isotope analysis during early, middle and late chick rearing.

Number of chick meals for: chick rearing phase
early middle late
Stable isotope analysis 8 10 11
Diet composition 34 10 10

BLOOD SAMPLES FOR STABLE ISOTOPE ANALYSES

A small blood sample (ca. 0.5 mL; maximum 1 mL) was taken from the brachial vein of adult Little Auks caught during late incubation (n=29), and during the early (n=10), middle (n=20), and late (n=42) chick rearing capture sessions (see above for capture dates). An additional blood sample for molecular sex identification was taken from those birds captured during late incubation and middle and late chick rearing. Molecular sex identification analyses have been completed by Prof. Jan Lifjeld and Dr. Fridtjof Mehlum at the Zoological Museum of Oslo University.
A small blood sample for stable isotope analyses was also taken from a total of 32 chicks during early (n=9; 18 July), middle (n=14; 4 August), and late (n=9; 10 August) chick rearing.
All stable isotope samples are currently being analyzed by Dr. Keith Hobson, Canadian Wildlife Service, Saskatoon, Saskatchewan.

EXTRA-PAIR PATERNITY

Additional blood samples were taken from 10 complete Little Auk families (both adults and chick) for DNA fingerprinting in collaboration with Prof. Jan Lifjeld and Dr. Fridtjof Mehlum at the Zoological Museum of Oslo University. All sampled adults were individually color-ringed, and all 10 nests were observed for three 24-hr periods (see below) to ensure that sampled adults were active parents and not just visiting the nest site when captured.

SEX DIFFERENCES IN PARENTAL PROVISIONING AND TIME AT THE COLONY

Fifteen accessible nests with visible entrances were found during the end of the incubation period. Both parents were captured in the nest-site, and identified with an individual colour ring combination and marker pen on the breast feathers. We took a small blood sample from each parent for molecular sex identification (see above). Due to the low density of nest sites that are both accessible and viewable, we were forced to split the 15 nests into two groups, requiring a team of two people to observe all nests simultaneously. A team of two people conducted a 24-hour watch during early chick rearing (19 July), and three observers conducted 24-hour watches during both middle (31 July) and late (8 August) chick rearing. The three- person team rotated observations and rest time in a tent set-up near the colony, so that two people were always observing while one rested. In addition to the three 24-hour watches, we also conducted four night watches (9, 10, 11, 12 August) during the peak diurnal fledging period (between 2200-0200). The time of colony arrivals and departures, standing or resting distances from nest-site, number and time of entrances and exits from the nest-site, number and timing of food deliveries, gular pouch size, specific aggressive behaviours, and butterfly flights were recorded for each of the individually marked birds during all watches.

ADULT MEASUREMENTS

Standard body measurements were taken from each adult caught: tarsus length using Vernier calipers, with precision ą 0.1 mm; culmen length using Vernier calipers, from the tip of the upper mandible to the anterior edge of the growing cere; straightened wing length with precision of ą 0.1 mm using a stopped ruler; and body mass using a spring balance, with precision of ą 1.0 g.

CHICK GROWTH

To determine timing of peak mass and mass recession, 15 chicks were measured (using the same measurements as for adults) every 2-4 d from 30 July until fledging.

COLLABORATORS

Prof. Jan Marcin Weslawski (Institute of Oceanology, Polish Academy of Sciences) is overall project leader for Little Auk work conducted at Hornsund, and is responsible for project coordination, chick diet analyses, and logistics at the Polish Polar Station at Hornsund. We are collaborating with Dr. Fridtjof Mehlum and Prof. Jan Lifjeld at the Zoological Museum of Oslo University for analyses of blood samples for molecular sexing and extra pair paternity, and with Dr. Keith Hobson at the Prairie and Northern Wildlife Research Center, Canadian Wildlife Service, for stable isotope analyses.

FUNDING SUPPORT
  • Polish Academy of Sciences
  • The Seabird Group
  • The Augustine Courtauld Trust
  • The Gino Watkins Memorial Fund
  • Alaska Pacific University
ACKNOWLEDGMENTS
We thank Magda Owczarek for her help in the field, and we're very grateful to Kasia Dmoch and Wojtek Walkusz for their skilled collection and identification of prey samples on the R/V Oceania. Thanks to the Alaska Science Center (U.S. Geological Survey, Anchorage, Alaska) for support during the preparation and write-up of our work. Many people provided encouragement and helped shape the aims of the expedition; we thank Nina Karnovsky, Dan Roby, Geir Gabrielsen, Tim Birkhead, Hallvard Strřm, Knud Falk, Martin Renner, Rosanna Paredes, Adrian Gall, and especially Lech Stempniewicz for their discussion, ideas and enthusiasm. Nina Karnovsky was a constant source of wisdom and encouragement throughout. Fridtjof Mehlum was a great help facilitating Norwegian handling and ringing permits. Michael Robin Haggie made the colour bands. Warm thanks to Richard and Janet Harding for UK-based logistic support and coordination, and to Dan Ruthrauff for last-minute logistics in Anchorage. We thank the crews of the Lance, Oceania and Norbjorn for their welcome and smooth transport. Last but certainly not least, we thank Lucjan Nowosielski (station leader), Tomasz Moczadlowski (assistant leader) and all our friends at the Polish Polar Station for their overwhelming hospitality, warm friendship, and efficient support.


Little auks in flight above Ariekammen, with Hansbreen and Fannytoppen in background

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