Factors influencing haul-out behaviour in non-reproductive Weddell seals (Leptonychotes weddellii) at Cape Royds, Antarctica.

• Main Author: Aspinwall, Arkady Michael Tadeusz
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Canterbury 2021
• Subjects: Antarctic; Southern Ocean; The Antarctic; Ross Sea; Weddell; Royds; Cape Royds; Antarc*; Antarctica; Weddell Seal; Weddell Seals
• Online Access: https://dx.doi.org/10.26021/11898; https://ir.canterbury.ac.nz/handle/10092/102764

The Weddell seals (Leptonychotes weddellii) are a fast-ice obligate phocid that plays a pivotal role as both predator and prey within the wider Antarctic marine ecosystem. Weddell seals face an uncertain future with the threat of habitat loss and pressures of marine resource extraction from the Southern Ocean. Monitoring of Weddell seal population dynamics provides us with an understanding of wider ecosystem health. Remote sensing technologies such as satellite imagery are increasingly being used to monitor remote populations in the Antarctic. However, satellite imagery needs to be validated by ground-truthing data, and an understanding of Weddell seal behaviour is critical for accurately interpreting Weddell seal counts from space. While the presence of a diurnal haul-out cycle in Weddell seals has been well documented, it is often not corrected for the variation of environmental conditions over a 24-hour period. I review 5,054 images from Cuddeback trail cameras between the 30th of October and 28th December 2017 from Cape Royds, Antarctica for a colony of non-reproductive Weddell seals. I use Generalised Additive Models to correct haul-out behaviour for the environmental variables of temperature, pressure, and wind-speed to determine a more accurate diurnal haul-out pattern. I find that more Weddell seals haul-out when air temperatures are higher, or wind speeds lower. Secondly, the haul-out cycle persists, with most seals hauled-out in the afternoon, and the fewest seals hauled out in the morning. Haul-out patterns can be used to calibrate satellite census counts of Weddell seals, integrating environmental parameters to correct time-of-day patterns may be the next step in generating better population estimates for the Ross Sea region and the wider Antarctic continent.