Census data were collected from two penguin monitoring sites in the Antarctic peninsula region between 1977 and 2015 using traditional census methods. Seabirds observed in this study are Adélie (Pygoscelis adeliae), chinstrap (P. antarctica), and gentoo (P. papua) penguins. The two study sites are the US AMLR Program sites at Cape Shirreff (Livingston Island) and Copacabana (King George Island) Antarctica.

We assessed reproductive success for the Adelie penguin colonies breeding on the Windmill Islands (Whitney Point, Odbert Island, Shirley Island, Blakeney Point 66°15' S, 110°33' E) from the 2011/12 – 2020/21 breeding seasons. We modelled nest survival against a range of potential environmental and behavioural drivers assessed over the same time period which are described below. Sites: We used four different sites with five camera locations for this study: Odbert Island = Odbt1, Shirley Island = Shrl1, Blakeney Point = Blak1, Whitney Point camera site 1 = Whit1, Whitney Point camera site 2 = Whit2. Individual nest identifier: For each nest, we developed a unique nest identifier (Year_Site_Nest). This includes the breeding season and camera site the nest was observed in, and also the number of the nest (1-10) observed. Reproductive success data: We used two metrics of reproductive success, breeding success and nest survival to creche. Breeding success was recorded as 0, 1, or 2 for each nest (0 = no chicks, 1 = one chick, 2 = two chicks). Nest survival was measured as binomial data and collected as 0,1 where 0 = nest failure and 1 = at least one chick survived to creche (Success.Fail). Nest failure occurred when either the parents abandoned the nest, both eggs failed to hatch, or chicks died. Failure and creche dates were recorded and the number of days since October 1 were calculated (Nest_Fail_date and Creche_Date). The breeding phase when failure occurred was noted for failed nests (Fail_Period). See BehaviouralData.csv. Environmental covariates: Southern Oscillation Index (SOI) and Southern Annular Mode (SAM) SOI and SAM values were averaged for the October – January (SOI_OctJan and SAM_OctJan) and the April to October (SOI_JulyJune, SAM_JulyJune) periods to correlate with the Adelie penguin reproductive cycle and the winter season respectively. The NOAA Climate Prediction Centre https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/monthly.aao.index.b79.current.ascii.table provided the SAM values, while the Australian Bureau of Meteorology http://www.bom.gov.au/climate/enso/soi/ provided the SOI data. SOI values range from ~-35 - +35, and the value is quoted as a whole number, and we used monthly values to obtain our reproductive cycle and winter value averages. SAM values are collected on an index where positive and negative values relate to different polar pressures, and similarly to SOI, values we used for reproductive cycle and winter season averages were collected monthly. See file BehaviouralData.csv. Fast ice extent (Fast_Ice) Shapefiles of fast-ice distribution in the Windmill Islands were obtained from the Natice website www.natice.noaa.gov. We measured the shortest distance between the four study sites and the fast-ice edge in ArcGIS during mid-November for each breeding season during the study (2011/12 – 2020/21). See file BehaviouralData.csv. Potential foraging overlap (Foraging_Intensity) Here, values were based on those presented in Southwell et al. (2021). This data is estimated using the ‘foraging radius approach’ developed by Critchley et al. (2018) and Handley et al. (2021) and recent population estimates for the region’s breeding sites, the distance between penguin breeding sites, and foraging distances from colonies to estimate the degree of potential overlaps between local breeding penguins when foraging at sea. See file BehaviouralData.csv. Windchill (WC) Mean windchill (°C) was calculated for incubation, guard, and creche for each breeding season. These are calculated from ambient air temperature, wind speed, and relative humidity recorded at Casey Station using the formula provided by the Australian Bureau of Meteorology http://www.bom.gov.au/info/ thermal_stress/. We calculated values for incubation, guard, and creche during each breeding season, and also for the period of time prior to incubation when penguins are arriving at the nest (arrival windchill: AWC; incubation: IWC;

These data have been superseded by a more recent dataset, described here - https://data.aad.gov.au/metadata/records/AAS_4088_Oblique_Aerial_Photos This dataset comprises oblique aerial photographs of multiple Adelie penguin breeding sites in East Antarctica. The photographs were taken using hand-held digital cameras from fixed-wing aircraft and helicopters used by the Australian Antarctic Program. The aircraft flew at or above the minimum wildlife approach altitude of 750 m with a horizontal offset distance from the site of approximately 500-600m. The date and exact location of the aircraft when each photo was taken is embedded in the EXIF data of each photo. All photographs that were taken are included despite varying image quality due to environmental conditions, camera type and altitude. Generally an attempt was made to photograph the entire breeding site (usually an island, occasionally an outcrop of continental rock) with a series of zoomed, overlapping photos. Sometimes this was not possible when the site was large, and in these cases the overlapping photos covered the locations where colonies were known to exist from previous survey work. In some cases a site was over-flown at an altitude of 1200m so that a single photo of the entire site could be taken. These photos are useful in piecing together the detailed photos. The database of potential Adelie penguin breeding habitat in Southwell et al. (2016a) was used to associate photos to a particular breeding site and structure how the photos are stored. The breeding site database has a unique identifying code of every site of potential breeding habitat in East Antarctica, and the sites are aggregated into sub-groups and then groups. The file structure in which the photos are stored has a combination of 'group' and 'split-year breeding season' at the top level (eg VES 2015-16 contains all photos in group VES (Vestfold Hills and islands) taken in the 2015-16 breeding season). Within each group-year folder are sub-folders for each breeding site where photos were taken (eg IS_72276 is Gardner Island in the VES group). If an overview photo was taken there are separate sub-folders for overview and detailed photos in the site sub-folder. Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

This dataset comprises oblique aerial photographs of multiple Adelie penguin breeding sites in East Antarctica. The photographs were taken using hand-held digital cameras from fixed-wing aircraft and helicopters used by the Australian Antarctic Program. The aircraft flew at or above the minimum wildlife approach altitude of 750 m with a horizontal offset distance from the site of approximately 500-600m. The date and exact location of the aircraft when each photo was taken is embedded in the EXIF data of each photo. All photographs that were taken are included despite varying image quality due to environmental conditions, camera type and altitude. Generally an attempt was made to photograph the entire breeding site (usually an island, occasionally an outcrop of continental rock) with a series of zoomed, overlapping photos. Sometimes this was not possible when the site was large, and in these cases the overlapping photos covered the locations where colonies were known to exist from previous survey work. In some cases a site was over-flown at an altitude of 1200m so that a single photo of the entire site could be taken. These photos are useful in piecing together the detailed photos. The database of potential Adelie penguin breeding habitat in Southwell et al. (2016a) was used to associate photos to a particular breeding site and structure how the photos are stored. The breeding site database has a unique identifying code of every site of potential breeding habitat in East Antarctica, and the sites are aggregated into sub-groups and then groups. The file structure in which the photos are stored has a combination of ‘group’ and ‘split-year breeding season’ at the top level (eg VES 2015-16 contains all photos in group VES (Vestfold Hills and islands) taken in the 2015-16 breeding season). Within each group-year folder are sub-folders for each breeding site where photos were taken (eg IS_72276 is Gardner Island in the VES group). If an overview photo was taken there are separate sub-folders for overview and detailed photos in the site sub-folder. These data also superseded an earlier dataset of 2009-2016 data - https://data.aad.gov.au/metadata/records/AAS_4088_Adelie_oblique_photos Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

Occupancy surveys in November 2009 and December 2010 (Southwell and Emmerson 2013) found a total of 2 Adelie penguin breeding sites in the Bolingen Island group between longitudes 75.333oE-75.912oE. The boundaries of breeding sub-colonies at 1 of these sites (Lichen Island, 73030) were subsequently mapped from vertical aerial photographs taken for abundance surveys on 20 November 2010 (for details of aerial photography see Southwell et al. 2013). The boundaries were mapped with a buffer distance of approximately 1-3 m from the perimeter of penguin sub-colonies. The other breeding site (73156) was photographed obliquely from a helicopter using a hand-held camera on 6 December 2010. Colony boundaries for this site were drawn and digitised by eye. Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

The dataset comprises scanned copies of the boundaries of Adelie penguin breeding colonies and sections of island coastlines made from aerial photographs taken between 9-15 December 1981. The original tracings by Michael Whitehead were scanned by Colin Southwell.

Fourteen colonies with breeding Adelie colonies were mapped this season in the Rookery Island group between the 29th November and 14th of December 2015. Subcolonies were mapped by circumnavigating the perimeter on foot while carrying a Garmin GPS (Etrex30) to record the track. When mapping the perimeter of the subcolonies, generally an average buffer distance of 2.5 meters was maintained between the mapper and breeding birds. However on Gibbney and Rookery Island one of the mappers was mapping at a distance between 3 and 5m. Buffer distances were reduced accordingly for the varying tracks to produce a combined average buffer distance of 2m in the final layer. Given this the boundary mapping for these two islands may vary in accuracy. Note on Gibbney and Giganteus there were at least two subcolonies on both islands that were mapped but the density of breeding birds in these mapped sections was much less than that in the surrounding colonies. Subcolonies were tagged with L at the end of their name in the track files. This will not be shown in the final layer and if information on this is needed then the subcolonies can be identified from the original track data or created shapefiles for the individual subcolonies on the island. Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

Two colonies with breeding Adelie colonies were mapped this season in the Rookery Island group in conjunction with colony counts. Subcolonies were mapped by circumnavigating the perimeter of sub-colonies on foot while carrying a Garmin GPS (Legend Cx) to log the track taken. The person walking the perimeter of the sub-colonies maintained a buffer distance of approximately 2.5m between themselves and the breeding birds along the sub-colony boundary. This buffer distance was reduced to approximately 2m in the final shapefiles. Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

An occupancy survey in December 2009-February 2010 and January 2011 found a total of 6 islands along the Knox coast had populations of breeding Adelie penguins. The survey in 2009/10 was conducted from a fixed wing aircraft and oblique aerial photographs were taken of occupied sites. The aerial photographs were geo-referenced to satellite images or the coastline shapefile from the Landsat Image Mosaic of Antarctica (LIMA, tile E157) and the boundaries of penguin colonies were digitised from the geo-referenced photos. Details for each island are: Merrit: Photographs taken on 1 February 2010 and geo-referenced to LIMA tile E157 Cape Nutt: Photographs taken on 5 January 2010 and geo-referenced to a Quickbird satellite image taken on 17 February 2011 Ivanoff Head: Photographs taken on 27 December 2009 and geo-referenced to LIMA tile E157 Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.

An occupancy survey in November 2006 found a total of 29 islands in the Robinson Group of islands had populations of breeding Adelie penguins. The boundaries of breeding colonies at 27 of these were mapped in Nov 2006 for abundance surveys. Nine of these breeding sites were remapped on the 29th of November 2013 in conjunction with colony counts. Subcolonies were mapped by circumnavigating the perimeter of sub-colonies on foot while carrying a Garmin GPS (Legend Cx) to log the track taken. The person walking around the sub-colonies maintained a buffer distance of approximately 2.5m between themselves and the breeding birds along the sub-colony boundary. This buffer distance was reduced to approximately 2m in the final shapefiles. Please refer to the Seabird Conservation Team Data Sharing Policy for use, acknowledgement and availability of data prior to downloading data.