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. (2008). Behavioural strategies of cormorants Phalacrocoracidae foraging under challenging light conditions. Ibis (Lond. 1859), 150, 231–239.
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. (2010). Sustained increase in food supplies reduces broodmate aggression in black-legged kittiwakes
. Animal Behaviour, 79(5), 1095–1100.
Abstract: The amount of food ingested by chicks has often been suggested as being the main proximate factor controlling broodmate aggression in facultatively siblicidal species. Although several experiments have demonstrated that short-term food deprivation causes a temporary increase in aggression, no study has, to our knowledge, experimentally manipulated overall food supplies and considered long-term effects on chick behaviour and life history traits. We provided supplemental food to breeding pairs of black-legged kittiwakes, Rissa tridactyla, over an entire breeding season and compared the aggressive behaviour of their chicks with that of chicks of control pairs. Control A-chicks (first to hatch) showed more frequent and intense aggression than their experimental counterparts. Furthermore, the more A-chicks begged and the lower their growth rate the more aggressive they were. The consequences of increased aggression for B-chicks (second to hatch) were lower begging rate, lower growth rate and lower survival. We thus provide evidence that a sustained increase in food availability affects broodmate aggression and chick survival at the nest and we discuss the various proximate and ultimate causes involved in the evolution of broodmate aggression.
Keywords: black-legged kittiwake, broodmate aggression, brood reduction, food amount hypothesis, food supplementation, Rissa tridactyla, siblicide,
Programme: 1162
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White J.W.C., Barlow L.K., Fisher D., Grootes P., Jouzel J., Johnsen S.J., Stuiver M. & Clausen H. (1997). The climate signal in the stable isotope of Summit, Greenland snow: results of comparisons with modern climate observations. J. Geophys. Res., 102(c12), 26425–26439.
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White J.W.C. (1993). Don't touch that dial. Nature, 364, 186.
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White J, Mirleau P, Danchin E, Mulard H, Hatch SA, Heeb P, Wagner RH, . (2010). Sexually transmitted bacteria affect female cloacal assemblages in a wild bird
. 1461-023X, 12, 1515–1524.
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White J, Helfenstein F, Danchin E, Hatch S A, Wagner R H, . (2006). Sperm age and reproductive performance in a strictly monogamous bird – an experimental study
. J. Ornithol., 147(5), 88.
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. (2011). Metabolic rate throughout the annual cycle reveals the demands of an Arctic existence in Great Cormorants
. Ecology, 92(2), 475–486.
Abstract: Aquatic endotherms living in polar regions are faced with a multitude of challenges, including low air and water temperatures and low illumination, especially in winter. Like other endotherms from cold environments, Great Cormorants (Phalacrocorax carbo) living in Arctic waters were hypothesized to respond to these challenges through a combination of high daily rate of energy expenditure (DEE) and high food requirements, which are met by a high rate of catch per unit effort (CPUE). CPUE has previously been shown in Great Cormorants to be the highest of any diving bird. In the present study, we tested this hypothesis by making the first measurements of DEE and foraging activity of Arctic-dwelling Great Cormorants throughout the annual cycle. We demonstrate that, in fact, Great Cormorants have surprisingly low rates of DEE. This low DEE is attributed primarily to very low levels of foraging activity, particularly during winter, when the cormorants spent only 2% of their day submerged. Such a low level of fo...
Keywords: arctic, basal metabolic rate, catch per unit effort, cpue, daily energy expenditure, day length, diving depths, field metabolic rate, foraging efficiency, great cormorant, greenland, phalacrocorax carbo, seasonal variation,
Programme: 388
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. (2011). The relationship between sea surface temperature and population change of Great Cormorants Phalacrocorax carbo breeding near Disko Bay, Greenland
. Ibis (Lond. 1859), 153(1), 170–174.
Abstract: Arctic seas have warmed and sea ice has retreated. This has resulted in range contraction and population declines in some species, but it could potentially be a boon for others. Great Cormorants Phalacrocorax carbo have a partially wettable plumage and seem poorly suited to foraging in Arctic waters. We show that rates of population change of Cormorant colonies around Disko Bay, Greenland, are positively correlated with sea surface temperature, suggesting that they may benefit from a warming Arctic. However, although Cormorant populations may increase in response to Arctic warming, the extent of expansion of their winter range may ultimately be limited by other factors, such as sensory constraints on foraging behaviour during long Arctic nights.
Keywords: Arctic warming, climate change, diving, Phalacrocorax, thermoregulation, vision,
Programme: 388
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. (2013). Energetic constraints may limit the capacity of visually guided predators to respond to Arctic warming
. J. Zool. (Lond.), 289(2), 119–126.
Abstract: For many polar species, climate change is likely to result in range contractions and negative population trends. For those species whose distribution is limited by sea ice and cold water, however, polar warming could result in population increases and range expansion. Population increases of great cormorants Phalacrocorax carbo in Greenland are associated with warmer sea surface temperatures, but the actual impact of environmental change on cormorant spatial ecology remains unclear. In the present study, we investigate how Arctic warming is likely to influence the distribution of cormorants in Greenland. Using geolocation data, we show that many individuals that breed above the Arctic Circle migrate south and winter at lower latitude. We then couple estimates of migratory flight costs with a model that predicts daily energy expenditure during winter on the basis of water temperature, ambient illumination during diving, dive depth and day length. This model shows that the most energy efficient strategy predicted for any breeding location is to migrate as far south as possible, and that, for a given wintering location, it is more energetically expensive to breed at high latitude. We argue that cormorants currently undertake a winter migration to escape the polar night and reduce winter energy costs and that their wintering grounds in Greenland will remain largely unchanged under Arctic warming. This is because low levels of ambient illumination during the polar night will continue to restrict foraging opportunities at high latitude during winter. Northward expansion of the breeding range will result in increased energy expenditure associated with long migratory flights, and the cost of such flights may ultimately limit the breeding range of cormorants. Such limitations are likely to represent a general constraint on the capacity of visually guided predators to respond to climate warming, and may limit the predicted poleward range shifts of these species.
Keywords: Phalacrocorax carbo, great cormorant, climate change, temperature, illumination, diving,
Programme: 388
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. (2013). Energetic constraints may limit the capacity of visually guided predators to respond to Arctic warming
. J. Zool. (Lond.), 289(2), 119–126.
Abstract: For many polar species, climate change is likely to result in range contractions and negative population trends. For those species whose distribution is limited by sea ice and cold water, however, polar warming could result in population increases and range expansion. Population increases of great cormorants Phalacrocorax carbo in Greenland are associated with warmer sea surface temperatures, but the actual impact of environmental change on cormorant spatial ecology remains unclear. In the present study, we investigate how Arctic warming is likely to influence the distribution of cormorants in Greenland. Using geolocation data, we show that many individuals that breed above the Arctic Circle migrate south and winter at lower latitude. We then couple estimates of migratory flight costs with a model that predicts daily energy expenditure during winter on the basis of water temperature, ambient illumination during diving, dive depth and day length. This model shows that the most energy efficient strategy predicted for any breeding location is to migrate as far south as possible, and that, for a given wintering location, it is more energetically expensive to breed at high latitude. We argue that cormorants currently undertake a winter migration to escape the polar night and reduce winter energy costs and that their wintering grounds in Greenland will remain largely unchanged under Arctic warming. This is because low levels of ambient illumination during the polar night will continue to restrict foraging opportunities at high latitude during winter. Northward expansion of the breeding range will result in increased energy expenditure associated with long migratory flights, and the cost of such flights may ultimately limit the breeding range of cormorants. Such limitations are likely to represent a general constraint on the capacity of visually guided predators to respond to climate warming, and may limit the predicted poleward range shifts of these species.
Keywords: climate change, Diving, great Cormorant, illumination, Phalacrocorax carbo, temperature,
Programme: 388
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