Knowles Kerry

Sex differences in Adélie penguin foraging strategies

Abstract Consistent sex differences in foraging trip duration, feeding locality and diet of breeding Adélie penguins (Pygoscelis adeliae) were demonstrated at two widely separated locations over several breeding seasons. Differences in foraging behaviour were most pronounced during the guard stage of chick rearing. Female penguins made on average longer foraging trips than males, ranged greater distances more frequently and consumed larger quantities of krill. In contrast, males made shorter journeys to closer foraging grounds during the guard period and fed more extensively on fish throughout chick rearing. Mean guard stage foraging trip durations over four seasons at Béchervaise Island, Eastern Antarctica and over two seasons at Edmonson Point, Ross Sea ranged between 31 and 73 h for females and 25 and 36 h for males. Ninety percent of males tracked from Béchervaise Island by satellite during the first 3 weeks post-hatch foraged within 20 km of the colony, while the majority (60%) of females travelled to the edge of the continental shelf (80–120 km from the colony) to feed during this period.

Gene flow on the ice: genetic differentiation among Adélie penguin colonies around Antarctica.

Each summer Adélie penguins breed in large disjunct colonies on ice‐free areas around the Antarctic continent. Comprising > 10 million birds, this species represents a dominant feature of the Antarctic ecosystem. The patchy distribution within a large geographical range, natal philopatry and a probable history of refugia, suggest that this species is likely to exhibit significant genetic differentiation within and among colonies. We present data from seven microsatellite DNA loci for 442 individuals from 13 locations around the Antarctic continent. With the exception of one locus, there was no significant genic or genotypic heterogeneity across populations. Pairwise FST values were low with no value > 0.02. When all colonies were compared in a single analysis, the overall FST value was 0.0007. Moreover, assignment tests were relatively ineffective at correctly placing individuals into their respective collection sites. These data reveal a lack of genetic differentiation between Adélie penguin colonies around the Antarctic continent, despite substantial levels of genetic variation. We consider this homogeneity in terms of the dispersal of individuals among colonies and the size of breeding groups and discuss our results in terms of the glacial history of Antarctica.

Population dynamics of the wandering albatross (Diomedea exulans) on Macquarie Island and the effects of mortality from longline fishing

The estimated breeding population of wandering albatrosses on Macquarie Island increased from 17 in 1956 to a maximum of 97 in 1966, and then declined at an average rate of 8.1% per year. Mark-recapture analysis shows that the population is not closed (i.e., subject to immigration and emigration). The decline is correlated with the onset of large-scale fishing for tuna in the southern hemisphere using longlines. The effect of longline mortality on the population dynamics of the wandering albatross is estimated. An annual number of longline hooks in the southern hemisphere tuna fishery of 41.6 million is calculated as the ceiling below which the population would begin to recover.

The diet of Little Penguins (Eudyptula minor) at Phillip Island, Victoria, in the absence of a major prey – Pilchard (Sardinops sagax)

Abstract The diet of Little Penguins (Eudyptula minor) was investigated in December 1995 and during the 1996–97 breeding period at Phillip Island, Victoria, Australia. The composition of the diet in this study differed markedly from that reported previously. Pilchard (Sardinops sagax), once a major prey, had virtually disappeared from the diet and Anchovy (Engraulis australis) showed a substantial decrease in frequency of occurrence. Instead, penguins had taken a temporal succession of juveniles of Red Cod (Pseudophycis bachus), Barracouta (Thyrsites atun), and Blue Warehou (Seriolella brama). Little Penguins had lower and higher than average breeding success in the 1995–96 and 1996–97, respectively, suggesting that the absence of Pilchards itself did not necessarily reduce the breeding success of Little Penguins. These findings contrast with those recorded in the 1980s when the absences of Pilchard and Anchovy had a negative impact on the penguins’ breeding performance.

Long-term breeding phenology shift in royal penguins

The Earths climate is undergoing rapid warming, unprecedented in recent times, which is driving shifts in the distribution and phenology of many plants and animals. Quantifying changes in breeding phenology is important for understanding how populations respond to these changes. While data on shifts in phenology are common for Northern Hemisphere species (especially birds), there is a dearth of evidence from the Southern Hemisphere, and even fewer data available from the marine environment. Surface air temperatures at Macquarie Island have increased by 0.62°C during the 30-year study period (0.21°C decade−1) and royal penguins (Eudyptes schlegeli) commenced egg laying on average three days earlier in the 1990s than during the 1960s. This contrasts with other studies of Southern Ocean seabirds; five of nine species are now breeding on average 2.1 days later than during the 1950s. Despite the different direction of these trends, they can be explained by a single underlying mechanism: resource availability. There was a negative relationship between the Southern Annular Mode (SAM) and median laying date of royal penguins, such that low-productivity (low SAM) years delayed laying date. This accords with the observations of other seabird species from the Antarctic, where later laying dates were associated with lower sea ice and lower spring productivity. The unifying factor underpinning phenological trends in eastern Antarctica is therefore resource availability; as food becomes scarcer, birds breed later. These changes are not uniform across the region, however, with resource increases in the subantarctic and decreases in eastern Antarctica.

The first five years of the Italian‐Australian joint programme on the Adélie Penguin: An overview

Abstract About 2000 breeding pairs of Adélie penguin (Pygoscelis adeliaë) nest in Edmonson Point (Wood Bay, 74°21’ S, 165°10’ E). The penguin colony is located on a raised terrace, divided into 13 discrete small units or colonies separated by unoccupied areas, where South polar skua (Catharacta maccormicki) nest. Colony layout, breeding chronology, breeding success, diet, and foraging areas were studied for five consecutive austral summers. Satellite transmitters, time‐depth recorders, and electronic tagging were used for monitoring feeding behaviour and nest attendance. An Automated Penguin Monitoring System was installed which records weight, identity, and direction of penguins as they move between the sea and their breeding colony. So far, the results of this study are documentation on colony trends, breeding biology, and differences in foraging strategies at different stages of the reproductive period and during different study seasons.

Re-constructing historical Adélie penguin abundance estimates by retrospectively accounting for detection bias

Seabirds and other land-breeding marine predators are considered to be useful and practical indicators of the state of marine ecosystems because of their dependence on marine prey and the accessibility of their populations at breeding colonies. Historical counts of breeding populations of these higher-order marine predators are one of few data sources available for inferring past change in marine ecosystems. However, historical abundance estimates derived from these population counts may be subject to unrecognised bias and uncertainty because of variable attendance of birds at breeding colonies and variable timing of past population surveys. We retrospectively accounted for detection bias in historical abundance estimates of the colonial, land-breeding Adélie penguin through an analysis of 222 historical abundance estimates from 81 breeding sites in east Antarctica. The published abundance estimates were de-constructed to retrieve the raw count data and then re-constructed by applying contemporary adjustment factors obtained from remotely operating time-lapse cameras. The re-construction process incorporated spatial and temporal variation in phenology and attendance by using data from cameras deployed at multiple sites over multiple years and propagating this uncertainty through to the final revised abundance estimates. Our re-constructed abundance estimates were consistently higher and more uncertain than published estimates. The re-constructed estimates alter the conclusions reached for some sites in east Antarctica in recent assessments of long-term Adélie penguin population change. Our approach is applicable to abundance data for a wide range of colonial, land-breeding marine species including other penguin species, flying seabirds and marine mammals.

Time for concern: is the health of Antarctica's wildlife in danger?

The high degree of isolation of Antarctica may well have protected its seals and birds from many of the diseases found in related species outside the continent. Our recent review of diseases in penguins has shown that birds taken into captivity are susceptible to a wide range of diseases, many of which have not been recorded in the wild. The same situation presumably applies to Antarctic seals. Adelie penguins in Antarctica have been shown to have antibodies to Newcastle disease virus, avian influenza virus and the Chlamydia group of bacteria. From this we could infer that wild birds have had contact with these diseases but, in the cases of viral diseases at least, a more likely explanation could be that the antibodies are the result of cross-infection with related but benign viral strains. There is no evidence to date that any major exotic diseases have been introduced into the Antarctic ecosystem. However, unless non-pathogenic strains are present to provide cross-immunity, all birds and seals are likely to be highly susceptible to such introductions.

Antarctic Communities: Species, Structure and Survival Edited by B. Battaglia, J. Valencia & D.W.H. Walton Cambridge University Press, Cambridge (1997). 464 pages. £95 (

Symposia on Antarctic Biology have been held every four to five years under the auspices of the Scientific Committee on Antarctic Research. The present volume presents the proceedings for sixth symposiumheldinVenice, Italy30May to 3 June 1994. Antarctic Biology is a term often used as if it were a scientific discipline in itself. The reality, however, is that Antarctic Biology is onlybiological research carried out in the south polarregions or on polar organisms. The more we study these organisms the more it is shown that there is a great commonality with organisms elsewhere a feature that this volume makes clear. The research papers included range across the biological spectrum and the principles and methods familiar to the biological community at large are applied to the investigation of the generally less familiar organism and communities ofwhich they are part. A compendiumofpapers such as this serves to bring together the most recent research and point to new directions for research for a very large region of the planet. Although the papers deal primarily with research in the Antarctic there is much of interest in this book for those with interests in the warmer regions as well as in the Arctic. The book contains 63 peer reviewed papers drawn fromthe 53 oral and 252 poster papers presented at the Symposium. The papers are grouped under five headings: I Biodiversity andevolution (9papers), 11. Community structure and function (1 5 papers), 111 Survival mechanisms (9 papers) IV Adaptive mechanisms (14 papers) and V Human impacts and environmental change (16 papers). The papers report on a wide range oftopics, some ofwhich do not fit easily under the section’s headings andindeedinto the theme ofthe book. The editors are to be commended, however, for providing a preface to each section which I d s the papers, notes the way in which each contributes to answer key questions and how the many individual efforts take the understanding of community ecology forward. I found these introductions excellent in explaining the relevance of many of the papers covering topics with which I was not familiar and having read the summaries I went on to read papers I might well have passed over. The publication is of avery high standard. The contributions are well presented and edited and supported by a comprehensive index. The three years from Symposium to publication is long and takes away from the timeliness of some of the papers. This was undoubtedly of concern to many of the authors and may impact on the willingness of authors at future symposia to allow their papers to be published in the proceedings rather than in journals. I have to admit, as editor of an earlier symposium volume, to a certain degree of sympathy with the editors who have had to extract key manuscripts from authors and reports from referees. I believe it is important to continue to hold similar symposia and to produce further volumes of proceedings. Such volumes provide signposts to the past and directions to the future for the biology of a whole continent where there are only a relatively small number of biologists. Antarctic Communities introduces two major new directions in Antarctic biological research. The first is the application of molecular biology to studies on evolution and populations and the role of specific gene sequences in controlling stress responses and behaviouralpatterns. The second is the studies of human impacts as a branch of biological science. These include the consequences of ozone depletion on organisms and biological systems, pollutants, introduced species, oil spills. Papers on birds and seals which have dominated earlier symposia are remarkably few. Old problems still exist. Species numbers, community diversity and the degree of endemism in the marine environment, and particularly in the benthos, have still to be determined. Taxonomic confusion on lichens still reigns. The large number of species and the supposedly high degree of endemism suggested by Dodge (1973) has been called into question. Castello & Nimmis suggest fewer species in total with a largerpercentage of them bipolar or cosmopolitan. They suggest that the lichen flora mainly originated by long-distance dispersal in the Quaternary. The moss Bryum argenteum (a haploid plant reproducing vegetatively) shows fromDNA analysis high levels of genetic variability. Present populations of this species must have arisen from genetically variable indigenous populations or as a result of immigration by a range of genetically different propagules or a combination of both. Bargelloni ef af. have provided a fascinating insight into phylogeny and evolution of Nototheniod fish for which there is no fossil record. Using partial sequences ofribosomal FWA mitochondrialgenes to construct a distance basedphylogenetic tree they estimated the time of divergence of species and related these to paleaoclimatic events including the development ofthe East Antarctic ice sheet and significant sea ice formation (1 5-1 1 Ma) and the northward expansion ofthe Antarctic polar front (6.5-5 Ma). In a similar manner the 16s rRNA sequences were used as a molecular clock to date the occurrence of representatives of the Antarctic prokaryotes. These organisms function optimally at a higher temperature