Population counts, resights and demography of Adelie Penguins in Mac. Robertson Land, Antarctica, 1991-2019
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We estimate population size in terms of the number of occupied nests for the Adélie penguin metapopulation in western Mac. Robertson Land, East Antarctica in 2009/10 and 2019/20. We also assessed demographic data from a single breeding site in the central part of this area (Béchervaise Island: 67°35'S, 62°49'E) including reproductive success, resight data, and fledgling mass from 1991/92 to 2019/20. We collated environmental covariates of potential drivers in this area over the same time period from sources described below. These are presented in the file “Time series demography and environmental covariates.xls”. Environmental covariates: Sea-ice concentration: Summer sea-ice concentration (SIC) was obtained for the area bounded by longitudes 60 - 65°E, to the south by the Antarctic coastline and the north by latitude 66.75°S. This approximately 250 km stretch of coastline incorporates the location of all Adélie penguin breeding sites across the metapopulation. The area defines the most northerly limit of fast-ice during chick rearing and encompasses the longitudinal range of the birds’ summer foraging activities. The sea-ice contained within this ‘near-shore’ region is predominantly composed of fast-ice (ice that is attached to land but covers seawater). Summer SIC was calculated as an average over the three-week period 25th December to 15th January when adults are guarding chicks for each breeding season. Winter SIC was determined in the following three areas of the penguins’ winter migratory route as defined previously. Each area was defined between specific longitudes and from 50°S south to the Antarctic coastline. The sea-ice contained within this area is composed of fast-ice near the coastline and pack-ice (all sea-ice that is not fast-ice) beyond the fast-ice edge. Two sectors defined the outward journey as they travelled westward towards their winter foraging grounds (50 - 65°E during March, and 30 - 50°E during April), a winter area (15 - 30°E during May-Jul) was considered as the sea ice became more extensive with both 15-100% SIC and 15-80% SIC which is considered more in line with suitable winter foraging ice conditions. The final area was associated with their eastwards journey towards the colony (30 - 50°E during Aug-Sep). For each area and time period, an average SIC was determined for each year in each of these areas. SIC values reflect the total area (km2) covered in sea-ice between either 15-100% or 15-80% SIC in each year and time period using 25x25km pixels. Sea-ice data were obtained from the National Snow and Ice Data Center (NSIDC) (Cavalieri et al. 1996) using Raadtools (Sumner 2017). Broad-scale climatic indices and local weather conditions: We determined the weather conditions during periods reflecting the end of the austral summer when the penguins were leaving their colonies (Feb-Mar) and the inter-breeding winter period (Apr-Sep). The Southern Oscillation Index (SOI) and the Southern Annular Mode (SAM) were included as broad indicators of climatic conditions, and local weather conditions included air and windchill temperatures. SOI was obtained from the Australian Bureau of Meteorology (www.bom.gov.au) and SAM from the NOAA Climate Prediction Centre (http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/aao/aao_index.html). Mawson Station local weather: Local weather data recorded at Mawson Station were obtained from the Australian Bureau of Meteorology. We considered two covariates: windchill and air temperatures both reported in °C. Windchill temperatures were determined from the ambient air temperature, wind speed and the relative humidity: AT= Ta +0.33e-0.7ws-4.0, where Ta is the dry bulb temperature (°C), e is the water vapour pressure (hPa), and ws is the windspeed (ms-1) at 10 m elevation. Water vapour pressure was determined from: (see the actual equation in the download file - "Emmerson_AADC Metadata Records_GCB_2022.docx" - unable to be reproduced here), where rh is the relative
Historical Adelie penguin breeding population estimates in the Australian Antarctic Territory
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Ecologists are increasingly turning to historical abundance data to understand past changes in animal abundance and more broadly the ecosystems in which animals occur. However, developing reliable ecological or management interpretations from temporal abundance data can be difficult because most population counts are subject to measurement or estimation error. There is now widespread recognition that counts of animal populations are often subject to detection bias. This recognition has led to the development of a general framework for abundance estimation that explicitly accounts for detection bias and its uncertainty, new methods for estimating detection bias, and calls for ecologists to estimate and account for bias and uncertainty when estimating animal abundance. While these methodological developments are now being increasingly accepted and used, there is a wealth of historical population count data in the literature that were collected before these developments. These historical abundance data may, in their original published form, have inherent unrecognised and therefore unaccounted biases and uncertainties that could confound reliable interpretation. Developing approaches to improve interpretation of historical data may therefore allow a more reliable assessment of extremely valuable long-term abundance data. This dataset contains details of over 200 historical estimates of Adelie penguin breeding populations across the Australian Antarctic Territory (AAT) that have been published in the scientific literature. The details include attributes of the population count (date and year of count, count value, count object, count precision) and the published estimate of the breeding population derived from those attributes, expressed as the number of breeding pairs. In addition, the dataset contains revised population estimates that have been re-constructed using new estimation methods to account for detection bias as described in the associated publication. All population data used in this study were sourced from existing publications.
Annual population counts at selected Adelie Penguin colonies within the AAT
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This indicator is no longer maintained, and is considered OBSOLETE. INDICATOR DEFINITION Breeding populations of Adelie penguins at Davis, Mawson and Casey (including Shirley Island and Whitney Point). TYPE OF INDICATOR There are three types of indicators used in this report: 1. Describes the CONDITION of important elements of a system; 2. Show the extent of the major PRESSURES exerted on a system; 3. Determine RESPONSES to either condition or changes in the condition of a system. This indicator is one of: CONDITION RATIONALE FOR INDICATOR SELECTION The breeding population of Adelie penguins is related to resource availability (nesting space and food), behavioural mechanisms (immigration/emigration and breeding effort/success) in addition to climate change and human impacts (fisheries, tourism, pollution, disturbance). Monitoring these colonies and interpretation of the data provides information on changes in the Antarctic ecosystem. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM Spatial scale: Colonies near Australian Stations - Casey (lat 66 deg 16' 54.5" S, long 110 deg 31' 39.4" E) Davis (lat 68 deg 34' 35.8" S, long 77 deg 58' 02.6" E) Mawson (lat 67 deg 36' 09.7" S, long 62 deg 52' 25.7" E) All colonies on - Shirley Island (lat 66 deg 16' 55.9" S, long 110 deg 29' 17.9" E) and Whitney Point (lat 66 deg 15' 08.6" S, long 110 deg 31' 40.1" E) Frequency: Annual surveys at Shirley Island and Whitney Point. Other colonies every 2-3 years, depending on logistical constraints. Measurement technique: Each colony is visited and all breeding birds are counted from the ground by two or three personnel performing replicate counts. Supplementary census data are obtained from oblique ground and aerial photographs. All breeding adults in a colony are counted. Considerations regarding disturbance associated with census visits are also incorporated into monitoring strategies. The lack of annual census data for some colonies does not reduce the value of these long-term monitoring programmes. RESEARCH ISSUES Adelie Penguin populations throughout East Antarctica have shown sustained, long-term increases for the past 30 or more years; in contrast, populations elsewhere around the Antarctic and on the Antarctic Peninsula have exhibited decreases or no clear long-term trends (Woehler et al. 2001). Greater coverage of colonies throughout the AAT would provide a more accurate estimate of the total annual breeding population in East Antarctica. In addition to basic inventory requirements, data on the population trends would contribute to a better understanding of the role of Adelie penguins in the Antarctic ecosystem, and provide managers with feedback or management strategies. LINKS TO OTHER INDICATORS
Population estimates of emperor penguins, Mawson coast, Antarctica
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Metadata record for data from ASAC Project 484 See the link below for public details on this project. ---- Public Summary from Project ---- Emperor penguins are the only birds that breed in the Antarctic winter. They feed mainly on fish and squid but also ingest krill. Changes in food availability due to oceanographic or climatic factors, or to the extent of sea ice (through the processes of global warming) will have a direct impact on the breeding success and population size of the penguins. By counting the number of males that incubate at mid-winter each year, we can monitor trends in their population size. Counts of fledglings in spring (November) tell us how successful the penguins bred. The download file contains an excel spreadsheet which presents a summary of known Emperor Penguin colonies in the area of the Australian Antarctic Territory (AAT), and a file which details counts of male emperor penguins at the Taylor Glacier colony. A description of the column headings used in the spreadsheet is below. Colony: Colony name lat, long: latitude and longitude of colony discovered: date colony was discovered current est pop (BP): Current estimated population size in breeding pairs - current as at date the colony was last seen last seen: date the colony was last seen counting method: method used to count the breeding pairs in the colony comments: any applicable comments reference: references relating to the colony Taken from the 2009-2010 Progress Report: Public summary of the season progress: Population size of colonies fluctuates which is why long term monitoring studies are necessary to detect trends. At the emperor penguin colony at Taylor Glacier, monitored continuously since 1988, a slight downward trend is apparent but is not (yet?) statistically significant. The colony was visited three times: once in winter to obtain an estimate of the number of adults in the colony (roughly equivalent to the number of breeding pairs), and twice during the late chick rearing season to estimate breeding success. The count of adults in 2009 was the lowest on record. Reasons for this are still unknown.
Adelie penguin breeding success for Bechervaise Island, Mawson
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Adelie penguin breeding success records for Bechervaise Island, Mawson since 1990-91. Data include counts of occupied nests and chick counts when either 2/3 of the nests have creched or when all nests have creched. Breeding success values are calculated as the number of chicks per occupied nest. Breeding Success = the number of chicks raised to fledging per nest with eggs Breeding success is calculated from four different whole island counts: 1) the number of incubating nests (i.e. the number of nest with eggs) - 'incubating nest count' 2) the number of brooding nests (i.e. the number of nests brooding chicks) - 'brooding chick count' 3) the number of chicks present when 2/3 of the nests have creched their chicks - '2/3-creche count' 4) the number of chicks present when all the nests have creche their chicks - 'fully-creche count' Each colony on the island is manually counted by field observers, using 'counters', three times each. Counts within 10% of each other are used to average the number of nests or chicks for each colony and then in later calculations to determine breeding success. Incubating nest counts are conducted on or about 2nd December; Brooding chick counts are conducted on or about the 7th January; 2/3-creche counts on or about the 19th January; and Fully-creche chick counts on or about 26th January. Whole island 2/3-creche and fully-creche chick count dates are determined from calculating when 2/3 and all study nests in the census area (study colonies) have creche their chicks. This work was completed as part of ASAC Project 2205, Adelie penguin research and monitoring in support of the CCAMLR Ecosystem Monitoring Project. The fields in this dataset are: Year Breeding success Occupied nests
Area - population relationships for Adelie Penguin colonies at Mawson.
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The relationship between colony area and population density of Adelie Penguins Pygoscelis adeliae was examined to determine whether colony area, measured from aerial or satellite imagery, could be used to estimate population density, and hence detect changes in populations over time. Using maps drawn from vertical aerial photographs of Adelie Penguin colonies in the Mawson region, pair density ranged between 0.1 and 3.1 pairs/m2, with a mean of 0.63 - 0.3 pairs/m2. Colony area explained 96.4% of the variance in colony populations (range 90.4 - 99.6%) for 979 colonies at Mawson. Mean densities were not significantly different among the 19 islands in the region, but significant differences in mean pair density were observed among colonies in Mawson, Whitney Point (Casey, East Antarctica) and Cape Crozier (Ross Sea) populations. This work was completed as part of ASAC project 1219 (ASAC_1219). The fields in this dataset are: Island Latitude Longitude Date Colony area Breeding Pairs Breeding Pairs per square metre Area per nest Number of nests Number of adults