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ABSTRACT: The non-breeding movements of marine birds were poorly known until recently, but this information is essential to understanding
the risk to different geographical populations from events on the wintering grounds. We tracked the migration routes and wintering
areas of Thick-billed Murre Uria lomvia from two breeding colonies in eastern Canada: Coats Island in northern Hudson Bay and The Minarets, Baffin Island, during
the period August 2007–May 2008 using geolocation loggers. Birds from The Minarets moved south rapidly post-breeding and wintered
principally off Newfoundland and southern Labrador, or between Newfoundland and southern Greenland, remaining south of 55°N
until at least the spring equinox. Those from Coats Island remained in Hudson Bay until at least mid-November, after which
they moved rapidly through Hudson Strait to winter in southern Davis Strait and the northern Labrador Sea, mostly north of
55°N. Many individuals stayed throughout the winter in areas of heavy ice cover. Adults from the two colonies appear to be
completely segregated in winter and those from Coats Island probably did not enter the area of the winter hunt in Newfoundland.
Unexpectedly, some birds from The Minarets wintered in waters beyond the continental slope and outside the distribution of
pack ice, demonstrating that particular individuals can be wholly pelagic throughout the winter. Coats Island birds returned
through Hudson Strait as soon as open water areas became available in spring. Their sojourn in Hudson Bay coincided very closely
with the occurrence of areas with <90% ice cover. In spite of the relatively large error in positions obtained from geolocation
loggers, our results demonstrated the value of these devices by uncovering a number of previously unknown aspects of Thick-billed
Murre non-breeding ecology in the Northwest Atlantic. Comparison of the non-breeding ecology based on SST experienced in winter
show that the winter niche is broader than hitherto assumed, demonstrating that separate populations may experience different
selection in the face of climate change.
Marine Biology 04/2012; 158(9):1929-1941. · 2.28 Impact Factor
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ABSTRACT: Past studies suggest that polar bears (Ursus maritimus) consume terrestrial food only opportunistically and derive little nutritional benefit from it. Here, we present observations
of at least 6 bears consuming large numbers of snow goose (Chen caerulescens) eggs at two locations in the eastern low Arctic in 2004 and 2006. We also report two records of a polar bear eating the
eggs and chicks of cliff-nesting thick-billed murres (Uria lomvia) in 2000 and 2003. Climatic warming has resulted in progressively earlier ice break-up in Hudson Bay, forcing bears ashore
much earlier than historical records indicate. Advancement in the nesting dates of birds has been more modest, and this mismatch
in timing could lead to an increasing overlap between the nesting period of birds and the period during which bears are on
land. At these sites in these years, bears were on land prior to the hatch of nests, and the predation that ensued was catastrophic
for the birds at a local scale. Although anecdotal, our observations highlight the complexity of trophic interactions that
may occur in a changing Arctic.
KeywordsPolar bear-
Ursus maritimus
-Snow goose-
Chen caerulescens
-Climatic change-Thick-billed murre-
Uria lomvia
-Predation
Polar Biology 04/2012; 33(8):1149-1153. · 1.66 Impact Factor
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ABSTRACT: Endogenous reserves influence both survival and reproduction of many waterfowl species, but little is known about reserve levels of most species during the nonbreeding season, particularly those wintering at high latitudes. We investigated whether age, sex, and season were related to carcass composition of northern common eiders (Somateria mollissima borealis) wintering in southwest Greenland during 1999–2002. Adults carried more lipid and protein than juveniles during all winters. Among both age classes, males and females had similar fat levels but males carried slightly more protein. There was no dramatic seasonal variation in lipid or protein content. This suggests that during the period of this study, these eiders did not experience large-scale nutritional shortfalls. As predicted, Greenlandic eiders carried more lipid reserves than eider populations wintering in more temperate environments. Contrary to prediction, there was little relation between reserve levels and photoperiod, ambient temperature, or hunting disturbance intensity. Our results suggest that both sexes are equally capable of dealing with nutritional deficits, and that juvenile birds are more prone to nutritional stress as evidenced by their consistently poorer body condition.
Polar Biology 04/2012; 29(7):585-594. · 1.66 Impact Factor
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ABSTRACT: Evidence that infectious diseases cause wildlife population extirpation or extinction remains anecdotal and it is unclear whether the impacts of a pathogen at the individual level can scale up to population level so drastically. Here, we quantify the response of a Common eider colony to emerging epidemics of avian cholera, one of the most important infectious diseases affecting wild waterfowl. We show that avian cholera has the potential to drive colony extinction, even over a very short period. Extinction depends on disease severity (the impact of the disease on adult female survival) and disease frequency (the number of annual epidemics per decade). In case of epidemics of high severity (i.e., causing >30% mortality of breeding females), more than one outbreak per decade will be unsustainable for the colony and will likely lead to extinction within the next century; more than four outbreaks per decade will drive extinction to within 20 years. Such severity and frequency of avian cholera are already observed, and avian cholera might thus represent a significant threat to viability of breeding populations. However, this will depend on the mechanisms underlying avian cholera transmission, maintenance, and spread, which are currently only poorly known.
PLoS ONE 01/2012; 7(2):e29659. · 4.09 Impact Factor
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ABSTRACT: Surgically implanted satellite transmitters have been widely used in studies of avian ecology, yet little is known about their potential impacts on birds. We implanted satellite transmitters with percutaneous antennae (approx. 50 g) in 17 female common eiders (Somateria mollissima) at a breeding colony in Arctic Canada. Among females implanted during incubation, 11 of 12 nests were abandoned within 1 week of being radioed. We observed no differences in the proportion of time that implanted female eiders allocated to basic behaviors. Radioed birds were more likely to pick or preen their abdominal (site of surgical incision) and posterior–dorsal (site of antenna exit) regions than unmarked females, although these behaviors were rare (approx. 0.3% of total time budget). Three of 10 females re-observed had a pronounced limp following surgery, but we observed no walking difficulties among these females in subsequent seasons, and we observed some implanted eiders nesting in subsequent years. Mark–resighting models suggest eiders with transmitters had lower apparent survival the year after implantation (67.0%; 85% CI: 47.8–81.9%) than did color-banded eiders (87.5%, 85% CI: 82.5–91.2%), but there was no model support for a survival difference in subsequent years. We conclude that transmitter implantation in common eiders leads to short-term changes in behavior and a decline in first year survival. We encourage researchers to collect similar data on their study subjects where possible and use it to determine the degree to which data are representative of the greater population. © 2011 The Wildlife Society.
Journal of Wildlife Management 08/2011; 75(7):1553 - 1557. · 1.52 Impact Factor
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ABSTRACT: Summary1. Optimality theory predicts that both timing of arrival and arrival state on the breeding area will determine reproductive timing and investment in migratory organisms. We tested this idea using a condition-dependent individual optimization model (Ardea68, 1980, 225 and The American Naturalist143, 1994, 698) in common eider ducks through descriptive data, path analyses and experimental manipulation.2. Our results support the causal pathways drawn from the optimization model indicating that individuals adjust their reproductive decisions as a function of their arrival date and body condition at arrival.3. Independent of body condition, early-arriving females had a longer pre-laying period, but still initiated their nests earlier, and produced larger clutches than late-arriving birds. Independent of arrival date, females in good condition laid earlier than those in poor condition. Manipulation of pre-laying female body condition confirmed that the relationship between condition and laying date was causal.4. Female common eiders appear to optimize reproductive decisions in response to both their external (i.e. environmental conditions affecting the egg-value) and internal (i.e. body condition) states. These adjustments seem to minimize the fitness costs of reproduction, in which higher clutch size is not associated with an apparent lower survival or future breeding probability.5. Our study emphasizes the importance of (i) simultaneously considering the timing of migration, the state of individuals and the seasonal change in egg-value to understand clearly birds’ breeding decisions and (ii) appreciating the potential proximate and ultimate factors explaining why some individuals delay breeding and/or produce small clutches.
Functional Ecology 05/2011; 25(3):671 - 681. · 4.57 Impact Factor
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ABSTRACT: Researchers often consider the importance of minimizing holding time during research activities; however, the long-term costs of such handling stress is rarely measured explicitly. As part of an ongoing study of common eiders (Somateria mollissima) at a breeding colony in East Bay, Southampton Island, Nunavut, we recorded duration of restraint for females captured during avian cholera epizootics (2007 and 2008) and monitored female fates (breeding probability, onset of laying, and survival) relative to holding time. Probability of death increased with holding time in 2007 from an estimated 0.05 for females held 20 min to 0.33 for females held for 150 min. In 2008, we responded by limiting holding time to <90 min and mortality was no longer positively correlated with holding time, although total mortality was greater due to increased severity of avian cholera. In both years, longer restraint durations delayed onset of egg-laying after capture by 0.5 days for each 10 min of additional restraint but did not prevent breeding. This delay of nest initiation did not enhance survival probability. Our results show that prolonged holding time can exacerbate mortality during epizootics and emphasize the importance of minimizing restraint time in wild birds, especially in the presence of diseases. © 2011 The Wildlife Society.
Journal of Wildlife Management 03/2011; 75(2):283 - 288. · 1.52 Impact Factor
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ABSTRACT: The strategy of relying extensively on stored resources for reproduction has been termed capital breeding and is in contrast to income breeding, where needs of reproduction are satisfied by exogenous (dietary) resources. Most species likely fall somewhere between these two extremes, and the position of an organism along this gradient can influence several key life-history traits. Common eiders (Somateria mollissima) are the only flying birds that are still typically considered pure capital breeders, suggesting that they depend exclusively on endogenous reserves to form their eggs and incubate. We investigated the annual and seasonal variation in contributions of endogenous and exogenous resources to egg formation in eiders breeding at the East Bay colony in the Canadian Arctic. We collected prey items along with females and their eggs during various stages of breeding and used two complementary analytical approaches: body reserve dynamics and stable isotope [δ(13)C, δ(15)N] mixing models. Indices of protein reserves remained stable from pre-laying to post-laying stages, while lipid reserves declined significantly during laying. Similarly, stable isotope analyses indicated that (1) exogenous nutrients derived from marine invertebrates strongly contributed to the formation of lipid-free egg constituents, and (2) yolk lipids were constituted mostly from endogenous lipids. We also found evidence of seasonal variation in the use of body reserves, with early breeders using proportionally more exogenous proteins to form each egg than late breeders. Based on these results, we reject the hypothesis that eiders are pure capital layers. In these flying birds, the fitness costs of a strict capital breeding strategy, such as temporary loss of flight capability and limitation of clutch and egg size, may outweigh benefits such as a reduction in egg predation rate.
Oecologia 03/2011; 165(3):593-604. · 3.41 Impact Factor
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ABSTRACT: Infectious diseases can have dramatic impacts on animal population dynamics, but how they influence vital rates remains understudied. We took advantage of the appearance of an avian cholera epizootic in an arctic colony of common eiders Somateria mollissima to study variation in juvenile survival and selection on hatch characteristics in relation to this highly infectious disease. Avian cholera is one of the most important infectious diseases affecting wild birds and is thought to primarily affect adult survival. Here, we show that avian cholera was associated with a 90% decline in duckling survival, leading to almost zero recruitment. Before the cholera outbreak, there was significant stabilizing selection on hatching date and significant positive directional selection on hatching mass. During cholera outbreaks, selection on hatch characteristics was no longer significant. These results were based on a low sample of surviving ducklings in cholera years, but suggested that date and mass at hatching did no longer affect duckling survival in the presence of cholera. These effects of avian cholera on post-hatching survival were likely not only the consequence of the disease per se, but also a consequence of an increase in predation rates that followed the emergence of avian cholera. Our results emphasize the dramatic direct and indirect impacts that infectious disease can have on vital rates, and thus population dynamics.
Journal of Avian Biology 12/2010; 42(1):39 - 48. · 2.28 Impact Factor
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ABSTRACT: Life-history theory predicts that there should be negative fitness consequences, in terms of future reproduction and survival, for parents with increased reproductive effort. We examined whether increased incubation demand affected innate immunity and body condition by performing a clutch-size manipulation experiment in black guillemots (Cepphus grylle). We found that plasma from males incubating experimentally enlarged clutches exhibited significantly reduced lysis titers compared with plasma from males incubating control clutches, while this was not observed in females. The increased incubation demand also impacted agglutination titers differently in males and females, although the effect of treatment was not significant in either sex. Among all birds, lysis titers increased and haptoglobin concentrations decreased from mid- to late incubation. Natural antibody-mediated agglutination titers and body condition were highly repeatable within the incubation bout and between years. This suggests that agglutination titers may serve as a reliable and resilient index of the immunological character of individuals in future studies. Overall, this study demonstrates that increased incubation demand impacts indices of innate immunity differently in males and females. The potential for different components of the immune system to be impacted sex-specifically should be considered in future studies linking immune function and life-history trade-offs.
Physiological and Biochemical Zoology 12/2010; 84(2):222-9. · 2.20 Impact Factor
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ABSTRACT: Individuals breeding in seasonal environments are under strong selection to time reproduction to match offspring demand and the quality of the post-natal environment. Timing requires both the ability to accurately interpret the appropriate environmental cues, and the flexibility to respond to inter-annual variation in these cues. Determining which cues are linked to reproductive timing, what these cues are predicting and understanding the fitness consequences of variation in timing, is therefore of paramount interest to evolutionary and applied ecologists, especially in the face of global climate change. We investigated inter-annual relationships between climatic variation and the timing of reproduction in Canada's largest breeding population of Arctic common eiders (Somateria mollissima) in East Bay, Nunavut. Warmer spring temperatures predicted both earlier mean annual laying dates and the earlier ice-free conditions required by ducklings for post-natal growth. Warmer springs had higher variation in this temperature cue, and the population laying distribution became increasingly positively-skewed in warmer summers, potentially indicating that more low-quality females had the opportunity to commence laying in warmer years. Females that timed laying to match duckling hatching just prior to fully ice-free conditions obtained the highest duckling survival probability. Inter-annual data on repeated breeding attempts revealed that the individuals examined show a similar degree of laying flexibility in response to climatic variation; however, there was significant individual variation in the absolute timing of laying within an average year. This work sheds light on how reproductive timing is related to and influenced by variation in local climate and provides vital information on how climate-related variation in reproductive timing influence a fitness measure in an Arctic species. Results are especially relevant to future work in polar environments given that global climatic changes are predicted to be most intense at high latitudes.
Oecologia 09/2010; 164(1):277-86. · 3.41 Impact Factor
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ABSTRACT: Plastic debris has become ubiquitous in the marine environment and seabirds may ingest debris which can have deleterious effects on their health. In the North Atlantic Ocean, surface feeding seabirds typically ingest high levels of plastic, while the diving auks which feed in the water column typically have much lower levels. We examined 186 thick-billed murres from five colonies in the eastern Canadian Arctic for ingested plastic debris. Approximately 11% of the birds had at least one piece of plastic debris in their gastrointestinal tracts, with debris dominated by user plastics. This is the first report of ingested plastics in an auk species in Canada's Arctic, and the highest incidence of plastic ingestion to date for thick-billed murres (Uria lomvia).
Marine pollution bulletin 09/2010; 60(9):1406-11. · 2.63 Impact Factor
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ABSTRACT: Arctic breeding shorebirds travel thousands of kilometres between their wintering and breeding grounds, yet the period over which they arrive and begin to initiate nests spans only several weeks. We investigated the role of local conditions such as weather, snow cover and predator abundance on the timing of arrival and breeding for shorebirds at four sites in the eastern Canadian arctic. Over 11 years, we monitored the arrival of 12 species and found 821 nests. Weather was highly variable over the course of this study, and the date of 50% snow cover varied by up to three weeks between years. In contrast, timing of arrival varied by one week or less at our sites, and was not well predicted by local conditions such as temperature, wind or snow melt. Timing of breeding was related to the date of 50% snow melt, with later snow melt resulting in delayed breeding. Higher predator abundance resulted in earlier nesting than would be predicted by snow cover alone. We hypothesise that when predation risk is high, the value of potential re-nesting exceeds the energetic risks of early breeding. Synchrony of breeding was significantly higher in late breeding years suggesting a relatively fixed date for the termination of nest initiation, after which nesting is no longer profitable.
Journal of Avian Biology 06/2010; 41(3):292 - 304. · 2.28 Impact Factor
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ABSTRACT: The Black Guillemot (Cepphus grylle) is a monomorphic, socially monogamous member of the Alcidae. Although aspects of their breeding and foraging ecology have been extensively studied, less is known about possible sex-based differences in morphology, nor whether Black Guillemots mate assortatively based on body size. Using molecular techniques, we identified the sex of 26 male and 21 female Black Guillemots captured in the Canadian Arctic, and measured six external body measurements: outer tarsus length, wing length, culmen length, bill depth, head plus bill length and body mass to test for sexual size dimorphism (SSD) and assortative mating. Overall, males were 1.7% and 8% larger than females in outer tarsus length and bill depth, respectively. Within breeding pairs, bill depth was the most dimorphic trait. Despite these morphological differences no evidence of assortative mating based upon body size was found. Thus, mate choice for body size does not appear to be an underlying mechanism of SSD in bill depth in Black Guillemots.
Waterbirds 09/2009; · 0.76 Impact Factor
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ABSTRACT: ABSTRACT Despite being widespread and easily observed, little is known about the life history of Glaucous Gulls (Larus hyperboreus). From 1984 to 2007, we examined their breeding biology and demography at Coats Island, Nunavut, Canada, where they nest alongside a colony of 30,000 pairs of Thick-billed Murres (Uria lomvia). The gulls fed mainly on murre eggs and chicks and by scavenging adult carcasses. The median age at first breeding was 5 yr, and the mean age was 4.8 ± 0.9 yr. Adult survival was estimated as 0.84 ± 0.03 (SE). The mean clutch size was 2.56 eggs and the mean number of young reared per year was 1.6 (range = 0.9–2.2). Birds reared at the colony provided 40% of recruits. Assuming that survival of locally reared chicks that emigrated was similar to that of chicks that returned to the colony, about 22% of the young gulls survived to breeding age. The timing of breeding by Glaucous Gulls appeared related to the timing of laying by murres. Although the demographic characteristics of Glaucous Gulls in our study were similar to those of populations of other large gulls, adult survival was at the lower end of the range for populations of large Larus gulls. There is some evidence that Glaucous Gulls exhibit lower survival than large gulls breeding in temperate areas, possibly because of contaminant burdens. In general, however, the demographic characteristics of large gulls show little variation and are probably a product of their common phylogeny.SINOPSISA pesar de su amplia distribución y fácil observación, poco se conoce sobre la historia de vida de la gaviota Glaucous Gull (Larus hyperboreus). Entre 1984 y el 2007, nosotros examinamos su biología reproductiva y demografía en la isla Coats, Nunavut, Canadá, en donde ellas anidan a lo largo y junto a una colonia de 30 000 parejas de Thick-billed Murres (Uria lomvia). Las gaviotas consumieron principalmente huevos, polluelos y carroña de las carcasas de los Murres adultos. La edad media de la primera reproducción fue 5 años y la edad promedio fue de 4.8 ± 0.9 años. La supervivencia de los adultos fue estimada en 0.84 ± 0.03 (SE). El tamaño promedio de la nidada fue de 2.56 huevos y el numero promedio de polluelos criados por año fue 1.6 (rango = 0.9–2.2). Aves criadas en la colonia aportaron el 40% de los reclutamientos. Asumiendo que la supervivencia de los polluelos criados localmente que emigraron fueron similares a la de los polluelos que retornaron a la colonia, aproximadamente el 22% de los polluelos de las gaviotas sobrevivieron hasta la edad reproductiva. El comienzo de la época reproductiva de la gaviota Glaucous Gulls esta aparentemente relacionada con el inicio de la puesta de huevos de los Murres. A pesar que las características demográficas de la gaviota Glaucous Gulls en nuestro lugar de estudio fueron similares a las de la poblaciones de otras gaviotas de gran tamaño, la supervivencia de los adultos estuvo en la parte baja del rango para poblaciones de gaviotas de gran tamaño del genero Larus. Existen evidencias que las gaviotas Glaucous Gulls, presentan baja supervivencia comparado a gaviotas grandes que se reproducen en las zonas temperadas, posiblemente debido a contaminantes. Sin embargo, en general, las características demográficas de las gaviotas grandes presentan poca variación y probablemente son el resultado de su filogenia común.
Journal of Field Ornithology 05/2009; 80(2):135 - 145. · 1.20 Impact Factor
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ABSTRACT: Fitness costs of reproduction are expected to be more pronounced when the environmental conditions deteriorate. We took advantage of a natural experiment to investigate the costs of reproduction among common eiders (Somateria mollissima) nesting at a site in the Arctic, where an avian cholera epizootic appeared at different magnitudes. We tested the predictions that larger reproductive effort (clutch size) is associated with lower survival or breeding probability the following year, and that this relationship was more pronounced under heightened exposure to the disease. Our results indicate that large clutch sizes were associated with lower survival of female eider ducks, but only when there was heightened exposure to avian cholera, as indexed by eider mortality on site. No cost was observed when cholera was absent or when lesser exposure was evident. This supports the hypothesis that fitness costs of high reproductive effort are higher under unfavourable conditions such as a disease epizootic, and further indicates that being a conservative breeder can increase survival probability, given the presence of a highly virulent disease.
Biology letters 05/2009; 5(2):278-81. · 3.76 Impact Factor
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ABSTRACT: The northern fulmar (Fulmarusglacialis) is a common seabird of the North Atlantic Ocean, with breeding colonies broadly dispersed between 45°N and 80°N. At higher
latitudes, breeding fulmars experience extensive sea-ice and presumably snow and low temperatures which do not affect fulmars
in the southern part of the breeding range. We studied the relationship between weather and reproductive success of northern
fulmars breeding at two colonies in the Canadian high Arctic. Collectively, hatching success, fledging success, and productivity
(chicks fledged per egg laid) were similar between our study and results from colonies located south of the Arctic. However,
a larger proportion of fulmars at apparently occupied sites (AOS) in high Arctic colonies appeared to forego egg-laying, resulting
in lower proportions of chicks fledged per AOS. Extreme inclement weather was the major factor influencing nesting success,
resulting in pulses of egg or chick loss during or immediately following major storms, although the mechanism of effects appeared
to differ between the two colonies. For Arctic fulmars, the risks of nest failure due to stochastic, deleterious weather events
may be offset by the predictable abundance of food supplies during chick-rearing in Arctic waters.
Polar Biology 03/2009; 32(4):529-538. · 1.66 Impact Factor
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ABSTRACT: The distribution and abundance of the Harlequin Duck (Histrionicus histrionicus) is poorly known in Arctic Canada. The limited historical information on this species is summarized, and new field surveys and interviews with Inuit hunters in 1998-2002 were also conducted. Recent data confirmed that Harlequins still occur on Baffin Island and are breeding. The majority of new data on this duck come from the Kimmirut area of southeastern Baffin Island, where surveys in the 1930s also found the species. However, it occurs as far west as Cape Dorset, and as far north as Clyde River. Few birds were observed during recent field surveys, suggesting that the population on Baffin Island is small and dispersed. Future monitoring of Harlequin Ducks in Nunavut will probably be best accomplished using community-based surveys by hunters.
Waterbirds 03/2009; · 0.76 Impact Factor
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ABSTRACT: Los cronogramas de reproducción de las aves podrĺan no cambiar a una tasa suficientemente rápida como para seguir el patrón actual de cambio climático, lo que causarĺa una reducción en su éxito reproductivo. Esta perturbación de la sincronĺa se conoce como la “hipótesis del desajuste.” Analizamos datos de la reproducción de Uria lomvia en la parte norte de la bahĺa de Hudson, Canada, para examinar la importancia relativa del ajuste y desajuste temporal de la reproducción en determinar las tasas de crecimiento de los pichones. Entre 1988 y 2007, la fecha de ruptura y desaparición del hielo oceanico en las areas circundantes se adelantó en 17 dias, y la fecha en que los conteos de U. lomvia exhibieron un pico (un ĺndice de la disponibilidad de alimento) se adelantó en la misma cantidad de tiempo. Sin embargo, la fecha mediana de postura de huevos se adelantó en sólo cinco dĺas, de modo que el número de dĺas entre la fecha de eclosión y las fechas de asistencia pico y de 50% de cobertura de hielo aumentó durante el periodo de estudio. E1 crecimiento de los pichones se redujo en aquellos años en los que los conteos de los adultos que los atendĺan presentaron picos a inicios de la tem-porada y temprano en relación con la fecha de eclosión. Estas observaciones sugieren que el momento en que tiene lugar la reproducción no se está adelantando para seguir la tasa de cambio de los eventos que suceden en el ambiente marino ártico, lo que conduce a una mayor dificultad en el aprovisionamiento de las crĺas. También demostramos que existe una relación entre el estado de la Oscilación del Atlantico Norte con la fecha de asistencia maxima de aves a la colonia, asĺ como con el crecimiento de los pichones. Esto sugiere que las interacciones océano—atmósfera de gran escala influencian la disponibilidad de presas para U. lomvia, aunque el mecanismo a través del cual sucede esto todavia es desconocido. Nuestros resultados apoyan la idea de que el desajuste de los ciclos reproductivos de las aves con los picos en la abundancia de alimento es una consecuencia importante del cambio climático global.
The Condor 02/2009; · 1.12 Impact Factor
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ABSTRACT: Effets de la Salinité de l’eau sur la Croissance et la Survie des Canetons de Somateria mollissima Le besoin en eau douce pourrait affecter la croissance et la survie des jeunes chez la sauvagine, incluant les canetons des canards de mer qui sont généralement élevés dans des habitats côtiers marins. Nous avons étudié l’influence de la salinité de l’eau sur la croissance et la survie de canetons de Somateria mollissima prélevés dans des nids sur Southampton Island, Nunavut, Canada, en juillet 2001 et 2002. En 2001, 50 canetons ont été séparés en cinq groupes (n = 10) et assignés à un traitement de salinité de l’eau pendant 6,5 jours. Les traitements incluaient de l’eau douce (<1 ppt NaCl), de l’eau saumâtre (11 ppt ou 21 ppt), de l’eau de mer (33 ppt), et un régime mixte (<1 ppt pour 12h, suivi de 33 ppt pour 6 jours). En 2002, l’expérience a été répliquée deux fois avec différents canetons. En général, le taux de croissance était négativement corrélé et le taux de mortalité positivement corrélé, avec la salinité de l’eau : 3%, 17% et 60% des canetons appartenant aux groupes avec les traitements <1-ppt, 11-ppt et 21-ppt, respectivement, sont morts alors que 100% sont morts pour les groupes avec les traitements 33-ppt et régime mixte. Les résultats confirment que de l’eau douce est requise pour la croissance et la survie des canetons de Somateria mollissima juste après l’éclosion. Ceci suggère que les sources d’eau douce dans les aires d’élevage des couvées constituent des éléments essentiels à une reproduction fructueuse.
The Auk 01/2009; · 2.16 Impact Factor
