Named feature - refers to a specific element of interest or value within a protected area that has been identified as a reason (or one of) for the designation of that site.
Maternal Investment – how much time and energy mothers invest in their pup.
UAV – Unmanned/Uncrewed Aerial Vehicles (AKA a drone).
Across the Southwest of England, the Isles of Scilly are recognised as being regionally important for Grey Seals. The islands support over 60% of all Grey Seal pups born annually in the southwest, meaning our local colony is regarded as being “Of exceptional conservation significance”. Hence why in 1996 the Islands were designated a European Marine site (also known as a Special area of Conservation) with Grey Seals (Halichoerus grypus) listed as a named feature.
Scilly is right at the southern end of Grey Seals normal rage and therefore are more likely to be impacted by climate change, which is why it is incredibly important to consistently and thoroughly monitor our Grey Seal colony for trends and changes. Which is exactly what Thomas Stone is doing as part of his PHD with the Marine Conservation, Ecology and Management group at the University of Oxford supported by Masters’ student Adam Grassly.
The overarching goal of this project is the long-term investigation into population trends of Grey Seals in Scilly, which is already well into its 4th year! To do this Thomas is conducting a full island census every 3 weeks across all the pupping sites in Scilly using drone imagery. Why every 3 weeks? Well, Grey Seal pups only keep that cute white fluffy coat for 3 weeks before moulting, so using this survey frequency means that Thomas and his team can count all the pups born in Scilly across the whole breeding season!
The Drone imagery is also being used to estimate the body volumes of individuals which is useful because it correlates very closely with body mass giving a great indication of how healthy the seals in Scilly are. The data collected in these surveys will be used by Thomas and his colleagues to produce population models to determine the current population trends for seals in Scilly and make projections for how we can expect number to change in the future. This information can then be used by the Trust to inform the ongoing management and conservation of Grey Seals in Scilly.
Additionally, the research team are investigating the importance of maternal investment on the growth and survival of pups. To do this, they are conducting daily drone surveys of Annet, one of the most important pupping sites on Scilly. The data from these surveys can then be used to track the progress and changes in body size by estimating the body volume of both mothers and pups. Conducting these surveys daily is vital as pups can gain up to 2kg a day alone from milk transfers from their mothers! The combination of all this information is then used (with the help of some fancy maths) to work out how much each mother invests in its pup and what impact this level of investment has on how the pup “does” long-term.
The final goal of Thomas’s project is to collect a series of UAV images of the same seals through time in different conditions and postures to use as a training dataset for an AI model. The hope is that this AI model would then be able to repeatedly recognise and identify the same individuals through time from UAV images. The team have highlighted that this is an incredibly ambitious goal, and it is possible that it may not work, but if it did the benefits would be huge. If they were successful, it would allow researchers to track the fate (survival, reproductive success, changes in body size etc) of individual seals (focussing on adult females) across years without causing disturbance, for example eliminating the need to tag individuals. Whilst still conceptual, if successful this methodology would be invaluable for monitoring populations, generating population models and looking at movement of individuals between and within locations as well as much more!
The Isles of Scilly Wildlife Trust has been supporting this important working by helping with general organisational costs such as boating. Members of our staff have been out with the team of researchers from Oxford to better understand the methods and techniques being used and ensure that any disturbance of the seals and other vulnerable wildlife is kept to an absolute minimum. We are working closely with Thomas and the team from Oxford University to ensure this vital information is being shared with the Trust and accessible to the local community in the future.
Despite the challenging weather over the last few weeks, the research team remain positive about the progress of the project. As of the end of August there were already 4 pups on Annet. They have already completed the initial survey of all the islands between breaks in the weather!
“The most exciting moment was definitely when we captured a pup being born during one of our surveys!”Oxford University
