There will be winners and losers as climate change alters the habitats of polar organisms. For an Adélie penguin (Pygoscelis adeliae) colony on Beaufort Island (Beaufort), part of a cluster of ...colonies in the southern Ross Sea, we report a recent population increase in response to increased nesting habitat as glaciers have receded. Emigration rates of birds banded as chicks on Beaufort to colonies on nearby Ross Island decreased after 2005 as available habitat on Beaufort increased, leading to altered dynamics of the metapopulation. Using aerial photography beginning in 1958 and modern satellite imagery, we measured change in area of available nesting habitat and population size of the Beaufort colony. Population size varied with available habitat, and both increased rapidly since the 1990s. In accord with glacial retreat, summer temperatures at nearby McMurdo Station increased by ~0.50 °C per decade since the mid-1980s. Although the Ross Sea is likely to be the last ocean with an intact ecosystem, the recent retreat of ice fields at Beaufort that resulted in increased breeding habitat exemplifies a process that has been underway in the Ross Sea during the entire Holocene. Furthermore, our results are in line with predictions that major ice shelves and glaciers will retreat rapidly elsewhere in the Antarctic, potentially leading to increased breeding habitat for Adélie penguins. Results further indicated that satellite imagery may be used to estimate large changes in Adélie penguin populations, facilitating our understanding of metapopulation dynamics and environmental factors that influence regional populations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Sexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by ...environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin (Pygoscelis adeliae) chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11%) as well as bill (~8%) and flipper length (~3%). We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d(-1) faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species--one krill (Euphausia crystallorophias) and one fish (Pleuragramma antarctica), with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors may impact the two sexes differently.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We conducted the first assessment of Adélie Penguin (Pygoscelis adeliae) chick survival that accounts for imperfect resighting. We found that when chicks are larger in size when they enter the crèche ...stage (the period when both parents forage at the same time and chicks are left relatively unprotected), they have a higher probability of survival to fledging. We investigated the relationships between growth, crèche timing, and chick survival during one typical year and one year of reduced food availability. Chicks that hatched earlier in the season entered the crèche stage older, and chicks that both grew faster and crèched older entered the crèche at a larger size. These relationships were stronger in the year of reduced food availability. Thus, parents increased their chicks' chance of fledging if they provided sufficient food for faster growth rates and/or extended the length of the brood-guarding period. Early nest initiation (i.e., early hatching) provided parents with the opportunity to extend the guard period and increase chick survival. However, to extend the guard stage successfully, they must provide larger meals and maintain higher chick growth rates, even if just one parent at a time is foraging, which previous work has shown is not possible for all individuals. We show that the factors governing tradeoffs in chick-rearing behavior of Adélie Penguin parents may vary in accord with environmental conditions, a result from which we can better understand species' adaptations to environmental changes. LAY SUMMARY When raising dependent young, animals must balance how much to invest in guarding the brood versus finding food for them. These so-called tradeoffs can influence how well the current brood grows and survives to independence. During two breeding seasons, one typical and one apparently food limited, we related Adélie Penguin chick survival rates to how fast they grew and the timing of a critical transition in brood-rearing when chicks switch from being guarded continuously by a parent to being left alone while both parents forage at the same time. We found that with a combination of early hatching and fast-growing, chicks entered the unguarded (“crèche”) stage older and larger and, therefore, had a better chance of surviving to independence. Certain parents can manage tradeoffs to maximize breeding success even during unfavorable conditions. These results can help us understand how populations will respond to changing climate and habitats. Realizamos la primera evaluación de la supervivencia de los polluelos de Pygoscelis adeliae que consideran los re-avistamientos imperfectos. Encontramos que cuando los polluelos son más grandes en tamaño al momento de ingresar a la etapa de guardería (el período en el que ambos progenitores se alimentan al mismo tiempo y los polluelos quedan relativamente desprotegidos), tienen una mayor probabilidad de sobrevivir hasta emplumar. Investigamos las relaciones entre el crecimiento, el tiempo de guardería y la supervivencia de los polluelos durante un año típico y un año de disponibilidad reducida de alimentos. Los polluelos que nacieron más temprano en la temporada entraron en la etapa de guardería más viejos, y los polluelos que crecieron más rápido y comenzaron la guardería más viejos entraron a la guardería con un tamaño más grande. Estas relaciones fueron más fuertes en el año de menor disponibilidad de alimentos. En consecuencia, los padres aumentaban la posibilidad de que sus polluelos emplumaran si proporcionaban suficiente alimento para alcanzar tasas de crecimiento más rápidas y/o si extendían la duración del período de cuidado de la nidada. La iniciación temprana del nido (i.e., eclosión temprana) brindó a los progenitores la oportunidad de extender el período de cuidado y aumentar la supervivencia de los polluelos. Sin embargo, para extender la etapa de cuidado con éxito, deben proporcionar comidas más grandes y mantener tasas de crecimiento de los polluelos más altas, incluso si solo uno de los progenitores a la vez está buscando alimento, lo que no es posible para todos los individuos, según lo indicado por trabajos anteriores. Mostramos que los factores que rigen las soluciones de compromiso en el comportamiento de cría de los polluelos por parte de los progenitores de P. adeliae puede variar de acuerdo con las condiciones ambientales, un resultado a partir del cual podemos comprender mejor las adaptaciones de las especies a los cambios ambientales.
The American Ornithological Society (AOS) is pleased to recognize Dr. Kristen Covino and Dr. Scott Taylor as the 2018 recipients of the Early Professional Awards: the James G. Cooper Young ...Professional Award and the Ned K. Johnson Young Investigator Award, respectively. The Early Professional Award winners presented plenary talks at the 2018 AOS Annual Meeting in Tucson AZ on Apr 13, 2018. The James G. Cooper Young Professional Award recognizes early-career ornithological researchers (up to three years post-Ph.D.) for their outstanding contributions in any field of ornithology. First awarded in 2009 by the Cooper Ornithological Society, this award recognizes early-career researchers for outstanding scientific research and contributions to the ornithological profession.
Abstract
Group-size variation is common in colonially breeding species, including seabirds, whose breeding colonies can vary in size by several orders of magnitude. Seabirds are some of the most ...threatened marine taxa and understanding the drivers of colony size variation is more important than ever. Reproductive success is an important demographic parameter that can impact colony size, and it varies in association with a number of factors, including nesting habitat quality. Within colonies, seabirds often aggregate into distinct groups or subcolonies that may vary in quality. We used data from two colonies of Adélie penguins 73 km apart on Ross Island, Antarctica, one large and one small to investigate (1) How subcolony habitat characteristics influence reproductive success and (2) How these relationships differ at a small (Cape Royds) and large (Cape Crozier) colony with different terrain characteristics. Subcolonies were characterized using terrain attributes (elevation, slope aspect, slope steepness, wind shelter, flow accumulation), as well group characteristics (area/size, perimeter-to-area ratio, and proximity to nest predators). Reproductive success was higher and less variable at the larger colony while subcolony characteristics explained more of the variance in reproductive success at the small colony. The most important variable influencing subcolony quality at both colonies was perimeter-to-area ratio, likely reflecting the importance of nest predation by south polar skuas along subcolony edges. The small colony contained a higher proportion of edge nests thus higher potential impact from skua nest predation. Stochastic environmental events may facilitate smaller colonies becoming “trapped” by nest predation: a rapid decline in the number of breeding individuals may increase the proportion of edge nests, leading to higher relative nest predation and hindering population recovery. Several terrain covariates were retained in the final models but which variables, the shapes of the relationships, and importance varied between colonies.
Unlike in many polar regions, the spatial extent and duration of the sea ice season have increased in the Ross Sea sector of the Southern Ocean during the satellite era. Simultaneously, populations ...of Adélie penguins, a sea ice obligate, have been stable or increasing in the region. Relationships between Adélie penguin population growth and sea ice concentration (SIC) are complex, with sea ice driving different, sometimes contrasting, demographic patterns. Adélie penguins undergo a complete molt annually, replacing all their feathers while fasting shortly after the breeding season. Unlike most penguin species, a majority of Adélies are thought to molt on sea ice, away from the breeding colonies, which makes this period particularly difficult to study. Here, we evaluate the hypothesis that persistent areas of high SIC provide an important molting habitat for Adélie penguins. We analyzed data from geolocating dive recorders deployed year-round on 195 adult penguins at two colonies in the Ross Sea from 2017 to 2019. We identified molt by detecting extended gaps in postbreeding diving activity and used associated locations to define two key molting areas. Remotely sensed data indicated that SIC during molt was anomalously low during the study and has declined in the primary molt area since 1980. Further, annual return rates of penguins to breeding colonies were positively correlated with SIC in the molt areas over 20 y. Together these results suggest that sea ice conditions during Adélie penguin molt may represent a previously underappreciated annual bottleneck for adult survival.
Age-related variation in foraging performance can result from both within-individual change and selection processes. These mechanisms can only be disentangled by using logistically challenging ...long-term, longitudinal studies. Coupling a long-term demographic data set with high-temporal-resolution tracking of 18 Adélie penguins (
, age 4-15 yrs old) over three consecutive annual cycles, we examined how foraging behaviour changed within individuals of different age classes. Evidence indicated within-individual improvement in young and middle-age classes, but a significant decrease in foraging dive frequency within old individuals, associated with a decrease in the dive descent rate. Decreases in foraging performance occurred at a later age (from 12-15 yrs old to 15-18 yrs old) than the onset of senescence predicted for this species (9-11 yrs old). Foraging dive frequency was most affected by the interaction between breeding status and annual life-cycle periods, with frequency being highest during returning migration and breeding season and was highest overall for successful breeders during the chick-rearing period. Females performed more foraging dives per hour than males. This longitudinal, full annual cycle study allowed us to shed light on the changes in foraging performance occurring among individuals of different age classes and highlighted the complex interactions among drivers of individual foraging behaviour.
Evaluating the fitness of organisms is an essential step towards understanding their responses to environmental change. Connections between energy expenditure and fitness have been postulated for ...nearly a century. However, testing this premise among wild animals is constrained by difficulties in measuring energy expenditure while simultaneously monitoring conventional fitness metrics such as survival and reproductive output.
We addressed this issue by exploring the functional links between field metabolic rate (FMR), body condition, sex, age and reproductive performance in a wild population.
We deployed 3D accelerometers on 115 Adélie penguins Pygoscelis adeliae during four breeding seasons at one of the largest colonies of this species, Cape Crozier, on Ross Island, Antarctica. The demography of this population has been studied for the past 18 years. From accelerometry recordings, collected for birds of known age and breeding history, we determined the vector of the dynamic body acceleration (VeDBA) and used it as a proxy for FMR.
This allowed us to demonstrate relationships among FMR, a breeding quality index (BQI) and body condition. Notably, we found a significant quadratic relationship between mean VeDBA during foraging and BQI for experienced breeders, and individuals in better body condition showed lower rates of energy expenditure.
We conclude that using FMR as a fitness component complementary to more conventional fitness metrics will yield greater understanding of evolutionary and conservation physiology.
A plain language summary is available for this article.
Plain Language Summary
Greater Sage-Grouse Vital Rates After Wildfire FOSTER, LEE J.; DUGGER, KATIE M.; HAGEN, CHRISTIAN A. ...
The Journal of wildlife management,
01/2019, Letnik:
83, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Greater sage-grouse (Centrocercus urophasianus) have been subject to long-term and continuing declines in population and habitat since European settlement of western North America. Increased wildfire ...activity constitutes a primary threat to the species in western portions of their range, with documented declines in wildfire-affected populations. Following a 187,000-ha wildfire in southeastern Oregon and northern Nevada, USA, we used global positioning system (GPS) telemetry to monitor nest initiation, nest survival, nesting habitat, and adult survival of female sage-grouse during 2013 and 2014. We used known-fate models in Program MARK to estimate daily nest survival and monthly adult survival in relation to temporal patterns, physiological characteristics of females, and habitat and land-cover characteristics. We assessed habitat characteristics using geographic information system (GIS)-derived measures of post-fire habitat condition and land cover. Nest initiation rate following the fire was comparable to that observed in unaltered habitat. We observed nesting rates of 90% and 100% during 2013 and 2014, respectively, and renesting rates of 23% and 57% during the same years. Daily nest survival was consistently low in comparison to rates observed in concurrent studies in the region, for first nests during both years, and for second nests during 2013, but survival markedly increased for second nests during 2014. Sage-grouse generally did not leave the fire perimeter to nest, with 64% and 73% of nests located in the fire boundary during 2013 and 2014, respectively. Approximately 27% of nests were located in burned habitat during 2013, and 20% of nests in 2014 were located in burned habitat. Adult survival varied by month, and although patterns of monthly survival were similar between years, monthly survival rates were significantly reduced from the beginning of the study through the end of the first post-fire growing season. Our results indicate that sage-grouse continue to use fire-affected habitat in the years immediately following wildfire and sage-grouse experienced lower nest survival and adult female survival than other populations during the same period.
Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy ...needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea‐ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins (Pygoscelis adeliae) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large‐scale movement of sea ice. We used remotely sensed sea‐ice movement data together with geolocation‐based penguin movement data to test the hypothesis that penguins use gyre‐driven sea‐ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea‐ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.
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