Abstract
During the 2019 breeding season (October-December), a battery-powered DIJ Inspire 2 drone was used to investigate a breeding southern elephant seal colony located at Patelnia Point (ASPA 128, King George Island, South Shetland Islands, maritime Antarctica). Twelve unmanned aerial vehicle (UAV) missions conducted 50–70 m above ground level (AGL) were completed to monitor the breeding ground with a maximum of 0.348 km2. The missions were planned in Pix4D Capture software. A drone, with the support of ground cameras and observations, was used to derive population counts, map harems, and track the phenology of the southern elephant seals. Based on data obtained from the UAV missions, orthophotomaps were created in PIX4D Mapper and then analyzed in QGIS. Calculated values of body size parameters such as body length and orthogonal body surface area were used to determine the age and sex of individuals. Analysis of the ranges of the harems on particular days, supported by an analysis of land conditions that generate physical barriers to the movement of animals, allowed zones in which the transformations of groups of harems took place to be determined. The hypothesized hermeticity of the designated zones was supported by statistical tests. The use of drones allows for comprehensive population analyses of the breeding colonies of elephant seals such as censuses of pups and adult individuals, determination of the sex ratio, and spatial analysis of the distribution of breeding formations. In addition, it allows for a more accurate result than ground counting.
Highlights
The southern elephant seal is the most studied pinniped species in Antarctica [1] and is divided into four genetically distinct populations: those from South Georgia, the Valdes Peninsula, Kerguelen, and Macquarie Island [2,3]
The first southern elephant seal bull usually appears at Patelnia Point in September, when the waters of Admiralty Bay are covered with patches of sea ice and temperatures remain well below 0 ◦C, with average values of −3.9 ◦C and −1.7 ◦C in September and October, respectively [37]
The following statements summarize our findings: 1. This paper confirmed that counting southern elephant seals using unmanned aerial vehicle (UAV) is more accurate than counting by humans, and it is strongly recommended that drones be used to monitor breeding colonies of southern elephant seals
Summary
The southern elephant seal is the most studied pinniped species in Antarctica [1] and is divided into four genetically distinct populations: those from South Georgia, the Valdes Peninsula, Kerguelen, and Macquarie Island [2,3]. The statuses of three subpopulations are unknown including that from the South Shetland Islands. Southern elephant seals on the South Shetland Islands have been found breeding only on King George Island [6], Livingston Island [7], and Nelson Island [8]. At Stranger Point (ASPA No 132, Figure 1B), censuses were conducted only between 1980 and 1988 [10] and in 1999 [11]. Further research focused mainly on the sex structure and physiology of southern elephant seals at Remote Sens. 2020, 12, 2964; doi:10.3390/rs12182964 www.mdpi.com/journal/remotesensing
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