J Ornithol (2007) 148 (Suppl 1):S155–S159 DOI 10.1007/s10336-007-0246-x

ABSTRACTS

Abstracts

Published online: 26 October 2007 Ó Dt. Ornithologen-Gesellschaft e.V. 2007

Wanless S: Climate change and north-east Atlantic seabirds Centre for Ecology and Hydrology, Hill of Brathens, Banchory, Aberdeenshire AB31 4BE, Scotland, [email protected] The coastal shelf seas around the north-east Atlantic are among the most biologically productive marine regions in the world. They are already at risk from a range of anthropogenic pressures, such as overfishing, development of wind and tidal energy schemes, and pollution. The situation is currently being exacerbated by marked and rapid changes due to global warming, and one of the highest profile issues attributed to climate change has been the recent widespread and catastrophic breeding failures at seabird colonies bordering the North Sea. Climate change will likely affect seabirds in two major ways: directly through an increased frequency of severe weather resulting in nests being washed off cliffs, breeding burrows becoming flooded etc, or indirectly through changes in prey availability. While instances of the former have been reported, the latter effect is generally thought to be more important and thus how climate change affects seabirds is to a large extent determined by how sensitive their preferred prey is to changes in temperature, salinity etc., and whether alternative prey is, or will become, available. In the north-east Atlantic, particularly northern parts of the North Sea, the lesser sandeel (Ammodytes marinus) is a key prey of many seabirds during the breeding season. Thus the main way climate is expected to affect seabirds in this area is through climate-induced changes in sandeel availability. However, elucidating such relationships is complicated by the fact that sandeels are also the target of a

major fishery. Long-term research on the seabird community on the Isle of May, off the southeast coast of Scotland, has shown that both adult survival and breeding success of a small surface-feeding gull, the black-legged kittiwake (Rissa tridactyla), were significantly reduced when winter sea surface temperature (SST) was high, with a one year lag in the relationship for breeding success (Frederiksen et al. 2004b) , results that were consistent with winter SST indirectly affecting kittiwakes through their food supply with sandeel recruitment being poorer in warmer years (Arnott and Ruxton 2002). In addition, birds bred less successfully and survived less well in years when a sandeel fishery was operating within 50 km of the colony. The results also indicated that the breeding success/temperature relationship was mediated mainly through 1-year old fish while that for adult survival was mediated by the availability of juvenile sandeels. Thus the analysis highlighted the additive negative effects of rising sea temperatures and a local sandeel fishery on kittiwakes at this colony and suggested that closing the fishery could significantly improve breeding output and survival, and thus population growth. Although surface-feeding species such as kittiwake and terns have generally been regarded as being the most sensitive to changes in prey, particularly sandeel, availability (Furness and Tasker 2000), recently diving species such as the common guillemot (Uria aalge) that bring back single items of food for their young, have also started to have bad breeding seasons. Examination of long-term data from the Isle of May on changes in sandeel size provides a clue to why this has been so, with the average length of fish in the early 2000s being only 60% of that 30 years ago (Wanless et al. 2004). The situation was particularly extreme in 2004 when mean sandeel length was the lowest

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recorded over a 30 year period, resulting in the energy value of an individual fish being greatly reduced. Sandeels made up an unusually small proportion of guillemot chick diet in 2004 and were replaced by sprat (Sprattus sprattus), another lipid-rich pelagic fish that should have provided sufficient energy for normal chick growth and fledging success. However, analyses of the energy content of fish brought in for the chicks revealed that values were dramatically lower than expected and thus chicks were being fed a low-lipid rather than a high-lipid diet (Wanless et al. 2005). Recent experimental work has suggested that poor diet at the chick stage could potentially have longer term effects because of impaired spatial learning abilities in juvenile birds (Kitaysky et al. 2006). There is thus good evidence that catastrophic breeding failures of seabirds at North Sea colonies in 2004 stemmed from problems lower down the food web and that not only the birds, but also the fish, were starving. However, despite the widely held view that climate change was responsible, definitive evidence remains lacking and more research is urgently needed. What is clear is that sea temperatures in the North Sea have been rising since the mid-1980s and the abundance and species composition of the plankton, particularly the copepod community, has changed dramatically (Beaugrand et al. 2003). Such conditions appear unfavourable for sandeel recruitment (Arnott and Ruxton 2002) and also for the survival and/or breeding of a wide range of seabirds (Frederiksen et al. 2004b; Harris et al. 2005: Grosbois and Thompson 2005; Votier et al. 2005). In highly seasonal environments one of the most obvious impacts of climate change is disruption of the timing of biological events. Numerous studies have shown that breeding phenology in birds varies in relation to the climate and temperature regime and moreover is an important fitness-related trait (Crick et al. 1997; McCleery and Perrins 1998). Recent research on the Isle of May using individually marked common guillemots has demonstrated that females tend to breed earlier following mild winters (as indicated by the winter North Atlantic Oscillation index), presumably because prey availability occurs earlier (Frederiksen et al. 2004a). However, although at the population level breeding time is highly plastic, there is remarkably little between-individual variation, i.e. all females respond in the same way and there appears to be strong stabilising selection against individuals that deviate from the average population-level response to the NAO (Reed et al. 2006). This result differs markedly from other avian studies where individual variation has been stronger and highlights the importance of social constraints on colonial seabirds and the limits they may impose on populations adapting to rapidly changing conditions.

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The evidence to date suggests that conditions in the North Sea are becoming less favourable for sandeels and thus for species such as seabirds that depend on them for food. However, it remains possible that the conditions will favour other prey species and that at least some seabirds may be able to take advantage of this. Recent surveys have indeed suggested that a new potential prey species is now available, with a dramatic increase in the abundance of the snake pipefish (Entelurus aequoreus) being recorded since 2003 (Kirby et al. 2006; Harris et al. 2007). The cause of this increase is currently unknown, although it does seem to be part of a general spread of Atlantic shelf species into the North Sea. Many seabird species have been recorded bringing snake pipefish to their chicks at colonies around the UK and feeding on them outside the breeding season. However, pipefish have a rigid, bony structure that makes them very difficult for birds, particularly chicks, to swallow and there are numerous records of chicks either choking to death on them or being unable to swallow fish brought in by their parents. Thus it seems highly unlikely that snake pipefish are a viable alternative food source for seabirds. Because seabirds are very long lived, often with annual adult survival rates in excess of 90%, have small brood sizes and take many years to start breeding, changes in population size tend to be rather slow. However, some dramatic declines in UK seabirds have occurred recently, although the extent to which these changes are climateinduced has not yet been investigated (Mavor et al. 2006). It is becoming clear that there are marked regional variations, with the biggest declines in seabird numbers and consistently lowest productivity being in the north of Britain, particularly Shetland. Sandeel distribution in British waters is patchy, with distinct spawning aggregations around the coast (Proctor et al. 1998; Pedersen et al. 1999). Differing fortunes of these sandeel stocks linked to changing ocean climate may thus be responsible for the pronounced geographical variation in breeding success observed in black-legged kittiwakes (Frederiksen et al. 2005, Frederiksen et al. in press) and now becoming apparent in other species that rely on sandeels. Ecologists are often accused of being alarmist, of taking a half-empty rather than a half-full view of the world. However, in the case of North Sea seabirds it is currently hard to be optimistic about the future and options to reverse the situation, at least in the short term seem limited. References Arnott, S. A. and Ruxton, G. D. (2002) Sandeel recruitment in the North Sea: demographic, climatic and trophic effects. Marine Ecology Progress Series 238: 199–210.

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Beaugrand, G., Brander, K. M., Lindley, A., Souissi, S. and Reid, P. C. (2003) Plankton effect on cod recruitment in the North Sea. Nature 426: 661–664. Crick, H. Q. P., Dudley, C., Glue, D. E., and Thomson, D. L. (1997) UK birds are laying eggs earlier. Nature 388: 526. Frederiksen, M., Harris, M. P., Daunt, F., Rothery, P. and Wanless, S. (2004a) Scale-dependent climate signals drive breeding phenology of three seabird species. Global Change Biology 10: 1214–1221. Frederiksen, M., Wanless, S., Harris, M. P., Rothery, P. and Wilson, L. J. (2004b) The role of industrial fishery and oceanographic changes in the decline of the North Sea black-legged kittiwakes. Journal of Applied Ecology 41: 1129–1139. Frederiksen, M., Wright, P. J., Harris, M. P., Mavor, R. A., Heubeck, M. and Wanless, S. (2005) Regional patterns of kittiwake Rissa tridactyla breeding success are related to variability in sandeel recruitment. Marine Ecology Progress Series 300: 201–211. Frederiksen, M., Edwards, M., Mavor, R. A. and Wanless, S. (in press) Regional and annual variation in Black-legged Kittiwake breeding productivity is related to sea surface temperature. Marine Ecology Progress Series. Furness, R. W. Tasker, M. L. (2000) Seabird-fishery interactions: quantifying the sensitivity of seabirds to reductions in sandeel abundance and identification of key areas for sensitive seabirds in the North Sea. Marine Ecology Progress Series 202: 253–264. Grosbois, V. and Thompson, P. M. (2005) North Atlantic climate variation influences survival in adult fulmars. Oikos 109: 273–290. Harris, M. P., Anker-Nilssen, T., McCleery, R. H., Erikstad, K. E., Shaw, D. N. and Grosbois, V. (2005) Effect of wintering area and climate on the survival of adult Atlantic puffins Fratercula arctica in the eastern Atlantic. Marine Ecology Progress Series 297: 283–296. Harris, M. P., Beare, D., Toresen, R., Nøttestad, L., Kloppmann, M., Do¨rner, H., Peach, K., Rushton, D. R. A., Foster-Smith, J. and Wanless, S. (2007) A major increase in snake pipefish (Entelurus aequoreus) in northern European seas since 2003: potential implications for seabird breeding success. Marine Biology 151: 973–983. Kirby, R. R., Johns, D. G. and Lindley, J. A. (2006) Fathers in hot water: rising sea temperatures and a Northeastern Atlantic pipefish baby boom. Biology Letters 2: 597–600. Kitaysky, A. S., Kitaiskaia, E.V., Piatt, J.F., and Wingfield, J.C. (2006) A mechanistic link between chick diet and decline in seabirds. Proceedings of the Royal Society Series B 273: 445–450.

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Mavor, R. A., Parsons, M., Heubeck, M. and Schmitt, S. (2006) Seabird numbers and breeding success in Britain and Ireland, 2005. Peterborough, Joint Nature Conservation Committee. (UK Nature Conservation, No.30). McCleery, R. H. & Perrins, C. M. (1998) Temperature and egg-laying trends. Nature 391: 30–31. Pedersen, S. A., Lewy, P. and Wright, P. (1999) Assessments of the lesser sandeel (Ammodytes marinus) in the North Sea based on revised stock divisions. Fisheries Research 41: 221–241. Proctor, R., Wright, P. J. and Everitt, A. (1998) Modelling the transport of larval sandeels on the north west European shelf. Fisheries Oceanography 7: 347– 354. Reed, T. E., Wanless, S., Harris, M. P., Frederiksen, M., Kruuk, L. E. B. and Cunningham, E. J. A. (2006) Responding to environmental change: plastic responses vary little in a synchronous breeder. Proceedings of the Royal Society series B 273: 2713–2719. Votier, S. C., Hatchwell, B. J., Beckerman, A., McCleery, R. H., Hunter, F. M., Pellatt, J., Trinder, M. and Birkhead, T. R. (2005) Oil pollution and climate have wide-scale impacts on seabird demographics. Ecology Letters 8: 1157–1164. Wanless, S., Wright, P. J., Harris, M. P. and Elston, D. A. (2004) Evidence for decrease in size of lesser sandeels Ammodytes marinus in a North Sea aggregation over a 30-yr period. Marine Ecology Progress Series 279: 237–246. Wanless, S., Harris, M. P., Redman, P. and Speakman, J. R. (2005). Low energy values of fish as a probable cause of a major seabird breeding failure in the North Sea. Marine Ecology Progress Series 294: 1–8.

du Plessis MA: Delayed dispersal and cooperative breeding in birds DST/NRF, Centre of Excellence at the Percy Fitzpatrick Institute, University of Cape Town, Rondebosch 7701, South Africa, [email protected] Cooperative breeding, a reproductive system in which more than a pair of individuals behave parentally towards young in a single nest or brood, has attracted significant attention over the past four decades. By the early 1990s, signs of agreement among workers in the field seemed to draw the earlier excitement in the field to a close. More recently, however, several new lines of argument have reinvigorated the field, not the least of which have been the

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debates centered on the role of its evolution on ecology, life history and phylogeny. In order to understand the evolutionary basis of cooperative breeding, a framework involving the dissociation of two key questions has generally been used. First, why do birds delay dispersal, and second, given delayed dispersal, why do the large majority of philopatric birds provide care to offspring on the territory in which they live? I propose to focus largely on the first question, but with cursory reference to some of the current thinking on the second. As reproductive maturity is reached, an individual is faced with the decision to breed independently or delay breeding. In the latter case, there are three options: delay breeding by staying on the natal territory either as a helper or as a non-helper, or to leave the natal territory as a ‘‘floater’’. If the cost and likelihood of successful breeding vary spatially and temporally, individuals may delay dispersal and/or independent breeding in response to the following: the quality of the territory, the depressibility of key resources, the risks associated with dispersal, and/or, in unpredictably variable environments, the seasonal variation in territory quality. The dispersal threshold model suggests that delayed reproduction may in some instances ultimately yield higher lifetime reproductive success than breeding independently in territories of poor quality. Various constraints and opportunities affect our attempts to understand the relative importance of the above factors. First, measures of territory quality have been fraught with complications and generally the best that can be done is to control indirectly for their effects in demographic analyses. Secondly, when breeders allow offspring to remain on the parental territory, there is potential for competitive conflict for access to critical resources on the territory. It is therefore important to consider the nature of the critical resources in terms of their depressibility. Thirdly, it is difficult to quantify the risks associated with dispersal accurately. In this connection, some colonial species breed in circumstances where most individuals in the colony have access to nest sites and experience similar environmental conditions. Thus, colonial birds are not necessarily exposed to the risks commonly associated with dispersal, which has been suggested to have a strong influence on the reproductive decisions that territorial cooperatively breeding birds take. Fourthly, in unpredictable environments, the severity of environmental conditions during different breeding seasons vary greatly. This presents some non-breeders with the opportunity to base their reproductive strategies on seasonal variation in territory quality. While it is possible to identify constraints operating on individual cooperative breeders or to agree on shared life-history characteristics, it still cannot be predicted when species will adopt the strategy of staying at home or to float non-territorially as non-breeders. The absence of strong predictive capacity to explain the

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phenomenon of delayed dispersal is of concern, particularly given that similar ecological and life-history features are shared by a large majority of species that do not delay dispersal and/or breed cooperatively. A potentially fruitful approach could lie in the study of delayed dispersal and cooperative breeding among irregular cooperative breeders or those species that show extensive variability in degree of sociality.

Merton DV: The Kakapo: some highlights and lessons from five decades of applied conservation Department of Conservation, PO Box 10420, Wellington, New Zealand, [email protected] The Kakapo (Strigops habroptilus) is a giant, flightless, nocturnal parrot endemic to New Zealand, in the monotypic subfamily Strigopinae. It is the largest parrot, adults weighing \4.0 kg. The kakapo has combinations of features not shared by any other bird and is unique amongst parrots in having a ‘‘lek’’ mating system. Its origin and relationships with other parrots are obscure and distant, and it is one of the last surviving members of a unique avianherbivore/plant system that disappeared with the extinction of the moas. The Kakapo was well-adapted to ground mammal-free conditions in prehistoric New Zealand, but proved pathetically vulnerable to predation by introduced mammalian carnivores. By the 1990s it had declined to extinction throughout its natural range and was critically endangered. It survives today on three off-shore islands to which it was relocated in 1975 for its protection. Attempts to avert its extinction were first made in the late 1890s when the New Zealand government transferred *375 birds to islands in Dusky Sound, Fiordland. Stoats reached the islands soon after, and the venture failed. Fifty years were to elapse before a further conservation attempt was made. In the late 1950s and 1960s, *10 birds were located within Fiordland’s Milford catchment and an attempt was made to establish a captive population. All nevertheless proved to be male, and most died within a few months. A third attempt to save the species was launched in 1974 and continues to the present time. Using a range of ‘‘close-order management’’ techniques on free-living birds, effort is now directed at maximizing survival of naturally produced eggs and young, increasing breeding frequency and managing genetic diversity in order to improve low fertility and hatchability. Techniques include manipulation of the breeding population to optimize genetic diversity; interisland transfer of breeding stock in order to capitalise on locally abundant foods that trigger breeding because Kakapo breed at two to five yearly intervals in synchrony with unusually heavy fruiting or seeding of certain native

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plants; support of breeding females through supplementary feeding; manipulation of female pre-breeding weights to increase the proportion of female young produced; artificial insemination to increase fertility and improve genetic representation; physical protection of nests; and intensive monitoring of nests throughout breeding coupled with intervention as necessary. A great deal has been learned during the course of the program—much of it relevant to other rescue and recovery programs. Since 1995, Kakapo numbers have increased by 68%; the global population now stands at 86 individuals.

Bezzel E: Birds in Germany: Some insights after nearly two centuries of comprehensive bird recording by birdwatchers and ornithologists Wettersteinstraße 40, 82467 Garmisch-Partenkirchen, Germany, [email protected] The breeding bird fauna of Germany forms a representative sample of the bird fauna of the temperate zone of the western Palaearctic region. According to atlases of breeding birds at the end of the 20th century, the breeding ranges of species in Germany match those in surrounding areas. Germany has no endemic species. Of species found on more grid units than expected, those of forest and farmland dominate; and those that are sparser and rarer are birds of oligotrophic open land and wetlands. The present differences in the ranges of species between Germany and adjacent parts of Europe seem to be determined more by available habitat than by zoogeographic gradients. Population sizes vary similarly. According to data in the BirdLife/EBCC European Bird Database, those breeding species that are abundant in Germany are similarly abundant in adjacent countries as well. Only several very rare species show different patterns; but there is no species that is rare in continental Europe yet common in Germany. In the middle of the 19th century, the well-known German ornithologist Johann Friedrich Naumann published a detailed review in which he bewails the decline of birds in central Germany. As a result of fifty years of birdwatching and experience in professional bird trapping for food, he saw ‘‘modern’’ practices of increased farming and human persecution as the main causes for alarming decreases. Thirty years later, Karl Theodor Liebe published a list, according to which more species had declined than increased in Thuringia, particularly the larger non-passerines, due mainly to human exploitation of forests and open land. So there is a reliable history of the German bird fauna from before the Industrial Revolution in the second half of

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the 19th century, an event that marks the beginning of the change which has affected so many bird habitats up to the present. Detailed local and regional bird reports have existed since that time, giving insight into the dynamics of species diversity in central Europe. More than a hundred years ago, the relative number of records indicating negative trends or extinction in local or regional populations per time unit seem to have been higher than during the 20th century. In the 20th century, rather more regional species seem to have increased than declined. This may be due to prior preoccupation with recording species that were declining or disappearing locally; but it is surely also a result of successful efforts in protecting threatened and rare species nowadays. For some of the larger areas of Germany, published data and documented birdwatching over periods of differing socio-economic and technical conditions enable reconstruction of the number of species breeding annually over a long period through the 20th century. In Bavaria, the number of species breeding annually has increased by seven percent over the last hundred years, and the number breeding per decade by eight percent. This small but nevertheless surprising increase is contradictory to the findings of some local studies, and has to be interpreted carefully because the present situation may be masked by several influences. The increase is unlikely to reflect more bird recording activity in recent decades, but may well result from conservation efforts. Though the balance between new and lost breeders is positive over the last hundred years, it has still fallen in the last three decades. The number of introduced species increased from less than one percent in the first decade of the 20th century to nearly eight percent in the last. Moreover, the balance between new and lost species is related to the size of the area involved indicating a species-area relationship. The decline in common and widespread species within the last decades has involved populations in smaller rather than larger areas. Thus in Bavaria, where the overall trend per decade is positive, turnover in species in smaller areas tends to be negative: species diversity reacts more sensitively at local than regional scales. A hundred years ago, birdwatchers and ornithologists in Germany focused on describing the situation rather than documenting the dynamics. So a huge amount of collected data was often published in detailed reports or lists. These irreplaceable historical sources not only provide information on the distribution of species but also such seasonal events as the arrival or departure of well-known migrants. The first seasonal records of migrants at the beginning of the 20th century compared with data collected a hundred years later indicate considerable changes in migratory behaviour in some species.

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