Phenology based adjustments to population survey data show no temporal change in the status or distribution of Cape petrels in the Vestfold Islands.

1. The Excel spreadsheet titled "1_Cape Petrel Population adjusted Estimates_Table1.xlsx is population survey count data and estimates of Cape petrels in the Vestfold islands, East Antarctica in 1974 and 2017. Numbers present the number of occupied nests in each year. Adjusted data as per ICESCAPE modelling and provides a value based on attendance of Cape petrels relative to phenology, values in brackets are the lower and upper confidence intervals based on 95% confidence. No data is where there was no survey data available; however a 0 indicates the island was searched, however no breeding birds recorded at that site. Four surveys of Cape petrel breeding populations have been conducted in the Vestfold Islands: 1972-73 (Johnstone et al 1973), 1974-75 (AAD unpublished data), 2016-17 (Louise Emmerson and Anna Lashko) and 2017-18 austral summers (Kimberley Kliska and Marcus Salton). Here we refer to breeding seasons as the year eggs were laid, which was also when surveys were conducted. For example, 1972-73 breeding season spans from October 1972 until April 1973 and is referred to as 1972; 1974/75 is referred to as 1974 and 2017/18 as 2017. In 1972, numbers of occupied nests and distribution were assessed from ground surveys across the Vestfold Islands region and Cape petrels were found only in the southern half of the Vestfold Islands. In 1974, all accessible islands in this southern region were again surveyed from the ground or sea ice for Cape petrels from Bluff Island south to the Sørsdal Glacier. In addition, the ‘Northern Islands’ (Figure 1) were opportunistically searched during seal surveys conducted from 1-8th November 1974, and no sign of breeding Cape petrels were recorded (Williams, pers. comm. 2020). The 2016 survey focussed on identifying islands with cape petrels present in the south from ground-based activities, and in the north from aerial surveys. The 2017 survey focused search effort on all the islands where breeding Cape petrels were observed in 1972 and 1974. Similar to the 1974 survey, the Northern Islands were opportunistically searched for Cape petrels during seal surveys between the 5-13th December 2017, and no Cape petrels were observed. To our knowledge, no Cape petrels have been observed in the Northern Islands. We are therefore confident that this study encompasses the entire Vestfold Islands population. To assess the status and temporal change in population numbers of Cape petrels in the Vestfold Islands, datasets from the three breeding seasons were analysed, with two complete datasets, one a combination of both the 1972 and 1974 surveys and one from the 2017 survey were used in the final analysis. Three islands surveyed in the 1972 survey were not surveyed in 1974, therefore to complete the dataset for the 1974, the counts from these three islands in 1972 (Magnetic, Turner and Gardner Islands) were used to fill data gaps in 1974. The complete dataset is referred to as the 1974 dataset. Historical count data from 1972 and 1974 seasons were obtained from Johnstone et al 1973 and the Australian Antarctic Division Davis Biology species log 1974, respectively. In the 1972 survey, breeding pairs were estimated at various locations by island name and symbol shape on hand drawn maps. These symbols indicated which side of an island Cape petrels were located. In the 1974 survey breeding pairs of Cape petrels were recorded, as counted from the sea ice or by ground searching on the 17th of November and the 17th of December 1974. Locations of breeding Cape petrels were recorded with cross marks on hand drawn maps, indicating which gully or slope on an island Cape petrels were located. To ensure consistency of survey dates, both the Davis Station log book 1974 and the personal journal of Richard Williams (the biologist who undertook the survey work in 1974) were cross checked for survey dates. In the 2017 season, the survey was conducted over three days (18th, 20th and 30th of November) at all known Cape petrel breeding colonies. At each breeding colony a combination of ground searches and/or binocular counts were conducted from a vantage point on the sea ice tens of meters perpendicular away from Cape petrel breeding areas with the aim of counting all occupied nests. Occupied nests were classified as Confirmed if a bird was present at the nest and Unconfirmed if a nest was suspected but no bird observed (i.e. bowls of small pebbles and/or large amounts of guano on rocks were indicative of nests). Counts of confirmed nests were used to represent the number of occupied nests in 2017, and were considered consistent with breeding pair estimates in historic surveys. Birds observed on ledges without guano were considered loafing rather than breeding and not included in counts. The locations of breeding colonies were recorded using a combination of geographical positioning system (GPS) locations, hand-drawn maps and photographs of breeding colonies from the vantage point where counts were conducted. To compare changes between surveys, the Vestfold Island region was divided into two sections: Northern Islands and Southern Islands. The Southern Islands were further classified into three areas labelled A, B, and C. Area A is the northern part of the Southern Islands and includes Bluff, Turner, Magnetic and Gardner Islands and the Davis Station, and has the most persistent fast ice. Area B includes Hawker and Mule Islands and is further south, with intermediate fast ice duration, and Area C includes Zolotov and Kazak Islands and is furthest south, just north of the Sørsdal Glacier, and has the earliest loss of fast ice (Figure 1).To account for potential uncertainty in the population counts, we assumed the counts were within ±10% (with 95 % confidence) of the true number present. We refer to this as ‘count repeatability’. 2. Attendance data titled "2_Attendance_CapePetrels_BluffIsland_2019-2020.csv." The attendance data is derived from images taken with a remotely deployed camera at the Bluff Island Cape petrel colony near Davis station, East Antarctica. This phenology of cape petrel at this colony was used to adjust historical and contemporary population estimates of the Cape Petrel population. The .csv file includes latitude and longitude, season, calendar time and date, and an occupied nest count from the 6th of November 2019 until the 8th of March 2020. The camera data were counted by Kimberley Kliska in June 2020 as part of a project investigating the phenology of Cape petrels in this region. 3. The dataset in folders titled "1970s polygons" and "2017 polygons revised" contains boundaries of Cape petrel nesting areas at numerous breeding sites on islands off the Vestfold Hills, Antarctica, for the purpose of assessing change in the bird’s distribution between the early 1970s and 2017 (Kliska et al. 2021 manuscript in review). Nest areas were identified in the early 1970s during three surveys over three years 1972, 73 and 74, and in 2017 during one survey that year. Details of the surveys in 1970s were presented in the ANARE SCIENTIFIC REPORTS publication N. 123 ‘The Biology of the Vestfold Hills, Antarctica’ 1972-73 summer, and in the Davis Biology Species Log 1974 (included 1973-74 summer and 1974-75 summer) (the latter by Richard Williams). Details of the survey in 2017 were presented in the Seabirds Research end-of-season field report Davis 2017-18 summer (by Kim Kliska and Marcus Salton). Polygons created from the 2017 survey are published with the AADC (Emmerson and Southwell 2020). In both periods the islands were surveyed either by ground searching an area on foot or by visualising the birds from a distance with or without binoculars, and then transcribing the area with nests onto hand drawn maps. These hand drawn maps were transcribed on to spatially projected electronic maps by Marcus Salton to represent the maximal perimeter of the cape petrel nest areas. In the 1970’s surveys, the depicted nesting areas represented locations where birds were observed sitting on or next to nests (or extensive guano deposits that were indicative of a nest). Birds that were on rocks and not associated with a nest or extensive guano deposits were considered non-breeding, and areas with extensive guano deposits without birds considered inactive nests, which were both omitted from the nesting area. The polygons that had already been created from the 2017 survey (Emmerson and Southwell 2020) were modified to match this representation of nesting area, by excluding areas within inactive nests (based on recollections of Kim Kliska and Marcus Salton). Polygons were created using R computing software version 4.0.2 (2020-06-22). The spatially projected electronic maps were derived from two shapefiles from the AADC: a coastline file (‘all_coast_poly_2003.shp’ DOI) and a contour file (‘vestfold_contours.shp’ DOI). These shapefiles were projected using Azimuthal equidistant, with the centre of the study area at latitude = -68.5785 and longitude = 77.8709 for visualisation purposes. Polygons are grouped by island. Not all islands have formal names. Therefore the number system created by Southwell (2016 a, b) for a project on Adelie penguins was adopted.

1. 标题为“1_Cape Petrel Population adjusted Estimates_Table1.xlsx”的Excel表格包含1974年和2017年南极洲东部Vestfold群岛的海角鹱（Cape Petrel）种群调查计数数据及调整后估算值。数值代表每年的占用巢数量。调整后的数据基于ICESCAPE模型，结合海角鹱相对于物候学（phenology）的出勤情况得出；括号内数值为95%置信水平下的置信区间（confidence interval）上下限。“无数据”表示无可用调查数据；而“0”表示该岛屿已被搜索，但未记录到繁殖鸟类。海角鹱繁殖种群在Vestfold群岛共进行过四次调查：1972-73年（Johnstone等人，1973）、1974-75年（澳大利亚南极局[AAD]未发表数据）、2016-17年（Louise Emmerson与Anna Lashko）及2017-18年南极夏季（Kimberley Kliska与Marcus Salton）。本文中繁殖季节以产卵年份指代，即调查开展年份：例如1972-73繁殖季跨度为1972年10月至1973年4月，记为1972年；1974/75年记为1974年，2017/18年记为2017年。1972年，通过Vestfold群岛区域的地面调查评估占用巢数量及分布，仅在群岛南部发现海角鹱。1974年，从Bluff岛向南至Sørsdal冰川的南部区域所有可访问岛屿均通过地面或海冰调查；此外，1974年11月1日至8日海豹调查期间对“北部群岛”（图1）进行了 opportunistic搜索，未记录到繁殖海角鹱（Williams，个人通讯，2020）。2016年调查通过地面活动聚焦南部有海角鹱分布的岛屿，北部则采用航空调查。2017年调查重点搜索1972年和1974年观测到繁殖海角鹱的所有岛屿；与1974年调查类似，2017年12月5日至13日海豹调查期间对北部群岛进行opportunistic搜索，未发现海角鹱。据我们所知，北部群岛从未观测到海角鹱，因此本研究可覆盖Vestfold群岛全域种群。为评估海角鹱种群数量的现状及时间变化，最终分析使用了三个繁殖季的数据：两个完整数据集（1972与1974年调查合并数据、2017年调查数据）。1972年调查的三个岛屿未在1974年被调查，因此为补全1974年数据集，采用1972年该三岛（Magnetic、Turner及Gardner岛）的计数填补空缺，补全后的数据集记为1974年数据集。1972年和1974年的历史计数数据分别来自Johnstone等人1973年研究及澳大利亚南极局Davis站1974年生物物种日志。1972年调查中，繁殖对数量通过手绘地图上的岛屿名称及符号形状估算，符号指示海角鹱所在岛屿的方位。1974年调查中，11月17日及12月17日通过海冰计数或地面搜索记录繁殖对数量，繁殖位置以手绘地图上的十字标记表示，指示岛屿上的沟壑或斜坡。为确保调查日期一致性，交叉核对了1974年Davis站日志与Richard Williams（1974年调查生物学家）的个人日记。2017年繁殖季，在所有已知海角鹱繁殖群（colony）开展了为期三天（11月18日、20日及30日）的调查；每个繁殖群结合地面搜索及/或从海冰上垂直于繁殖区数十米的观测点进行双筒望远镜计数，目标为统计所有占用巢。占用巢分为“确认”（巢中有鸟）和“未确认”（疑似巢但无鸟观测，如小卵石碗状结构及/或岩石上大量鸟粪指示巢存在）两类。2017年采用确认巢计数代表占用巢数量，与历史调查的繁殖对估算一致；未与巢或大量鸟粪关联的岩石上鸟类视为游荡（非繁殖），不纳入计数。繁殖群位置通过全球定位系统（GPS）坐标、手绘地图及观测点拍摄的繁殖群照片记录。为比较调查间变化，Vestfold群岛区域分为北部群岛和南部群岛；南部群岛进一步划分为A、B、C三个区域：A区为南部群岛北部，含Bluff、Turner、Magnetic及Gardner岛与Davis站，拥有最持久的固定冰；B区含Hawker及Mule岛，更靠南，固定冰持续时间中等；C区含Zolotov及Kazak岛，最靠南（Sørsdal冰川以北），固定冰消融最早（图1）。为考虑种群计数的潜在不确定性，假设计数在真实数量的±10%范围内（95%置信水平），称为“计数重复性”。

2. 标题为“2_Attendance_CapePetrels_BluffIsland_2019-2020.csv”的出勤数据集来自南极洲东部Davis站附近Bluff岛海角鹱繁殖群的远程部署相机拍摄图像。该繁殖群的海角鹱物候学数据用于调整其历史及当代种群估算。csv文件包含纬度、经度、季节、日历时间与日期，以及2019年11月6日至2020年3月8日的占用巢计数。相机数据由Kimberley Kliska于2020年6月计数，作为该区域海角鹱物候学研究项目的一部分。

3. 文件夹“1970s polygons”与“2017 polygons revised”中的数据集包含南极洲Vestfold Hills附近岛屿多个繁殖点的海角鹱筑巢区边界，用于评估1970年代初至2017年的分布变化（Kliska等人，2021年待审手稿）。筑巢区在1970年代三次调查（1972、1973、1974年）及2017年一次调查中确定。1970年代调查细节见ANARE科学报告第123号《南极洲Vestfold Hills的生物学》（1972-73夏季）及Davis站1974年生物物种日志（含1973-74及1974-75夏季，由Richard Williams记录）；2017年调查细节见海鸟研究2017-18夏季Davis站季末报告（Kim Kliska与Marcus Salton）。2017年调查生成的多边形已由澳大利亚南极数据中心（AADC）发布（Emmerson与Southwell，2020）。两个时期均通过地面步行搜索区域或使用/不使用双筒望远镜远距离观测鸟类，再将巢区转录到手绘地图；Marcus Salton将这些手绘地图转录为空间投影电子地图，以表示海角鹱巢区的最大周长。1970年代调查中，筑巢区代表观测到鸟类坐于巢上或巢旁（或大量鸟粪指示巢存在）的位置；未与巢或大量鸟粪关联的岩石上鸟类视为非繁殖，无鸟的大量鸟粪区视为非活跃巢，两者均排除在筑巢区外。2017年已创建的多边形（Emmerson与Southwell，2020）经修改以匹配该筑巢区定义，排除非活跃巢区域（基于Kim Kliska与Marcus Salton的回忆）。多边形使用R计算软件4.0.2版本（2020-06-22）创建；空间投影电子地图源自AADC的两个shapefile文件：海岸线文件（“all_coast_poly_2003.shp” DOI）及等高线文件（“vestfold_contours.shp” DOI）。这些shapefile采用方位等距投影，研究区域中心坐标为纬度=-68.5785、经度=77.8709（用于可视化）。多边形按岛屿分组；并非所有岛屿均有正式名称，因此采用Southwell（2016a,b）为阿德利企鹅项目创建的编号系统。