We entered our 2021 annual Seabird survey season with a spring in our step, after the disappointments of 2020 whereby the main survey windows were missed as a result of Covid-19.  Annet surveys were back on the table and our full monitoring went ahead as planned; with interesting findings once again!

Scilly's Seabird breeding records comprise one of the best long-term environmental data sets we have for our Islands; with detailed all-Island counts first being conducted in 1970.

Recording of numbers of breeding Seabirds on Annet started in 2006, and across St Agnes and Gugh in 2012; these surveys have been carried out on an annual basis ever since (other than a little blip last year, courtesy of Covid-19). 

These records and datasets have allowed us to identify worrying declines in many of our breeding Seabird populations.

One of the most significant, and possibly most shocking, findings is that since 1983 we can evidence our breeding Seabird pairs, here in Scilly, have declined by 31.3%!  Further analysis enables us to show that five species of Seabird have declined across Scilly by more than 20% since 2006; those being the Kittiwake -89%; Common tern -65%; Lesser black-backed gull -26%; Herring gull -22%; European shag -21%.

We know that our Seabirds are in trouble (not just here in Scilly, but globally) what is less certain is exactly what is causing those declines; it is likely that a number of complex, and in many-cases linked, factors are contributing to the breeding successes and failures recorded across our Islands, some of which we'll touch on here.  

Below we share some of the highlights!  You can read the full report here.

Start of the Season:

The Seabird Survey season started, as usual, in late April with boat trips to count returning breeding adult Puffin on land, at sea and in the air around Annet; the counts are done at this time to ensure accurate records of breeding adults prior to the juvenile, non-breeding Puffins returning to the Islands in June. 

Outcome:  Annet counts indicated that numbers of breeding Puffin remain stable for another year, which we have to take as incredibly positive given that numbers in other locations across the UK are reported to be in decline.

Moving into May, surveying of our Gull species (Herring, Lesser and Greater black backs) begins along with visits to various nesting sites to start Shag and Manx shearwater counts.  In addition to this we carry out the first of the season's visits to the closed Island of Annet; a highlight for our Team which we were able to share with a handful of lucky individuals this year, including 3 Five Islands Academy students who joined us on their work experience placements and 11 residents who assisted with our first ever community coastal clean to remove marine debris.

Scilly is internationally important for the Lesser black-backed gull, holding just over 10% of the UK's breeding population.  We know that Gulls as a group can be incredibly unpopular with residents and visitors but as a species their numbers are in decline globally and consequently they are protected.  They have a bad reputation due to their opportunistic, scavenging nature and often get the blame for any multitude of problems; many of which can be traced back to humans in origin.

This year we embarked on some exciting new trial surveys with our Gulls, for both breeding pairs and fledging chicks, with drones.  Our trials took place on Samson and Gugh with some really interesting results, and food for thought in relation to how we carry out future surveys.

Traditionally, we use a "walk-through" method for counting Gull nest; a forensic style line-up whereby observers, a metre or two apart, systematically cover all the ground in a colony and count active nests (fully formed nests, with or without eggs and later in the season, chicks).  This is a recognised and effective, but relatively invasive, technique which causes temporary disturbance and the potential for error in terms of missing or double counting nests.  Additionally it requires a fair amount of "man-power" (ordinarily 5-7 Team members/observers).

In contrast drone surveys can be carried out with a team of 2 with the possibility of less disturbance; the results from our trials were interesting and surprising.

Outcome:  On Gugh the drone survey proved useful and effective, with the birds being unconcerned by the presence of the drone at a height of 25-30 metres.  In contrast on Samson, even at a height of 70 metres, disturbance was still occurring and the resulting quality of images obtained were not particularly useful.  However, Gareth (our drone operator) has plans to upgrade to a newer, improved drone in time for the 2022 survey season which will allow for clearer images at greater heights, so watch this space!

In terms of how the Gulls are fairing?  Our internationally important Lesser black backed gulls appear to have stablised in relation of numbers at the Gugh colony, with 397 pairs recorded (this is decline of more than half since 2006, but on par with the average recorded since 2012).

Our Herring gull numbers decreased by 22% between 2006 and 2016, with the Tresco colony being monitored becoming deserted in 2014 and numbers in the Samson colony declining; the number of birds in the third monitored colony in Hugh Town has seen a substantial increase in productivity (the number of chicks successfully fledged).

As we moved into June we added FulmarKittiwake and Common tern to our survey trips. 

Fulmar are monitored from the sea at two main colonies (Menawethan and near the Daymark on St Martin's).  Kittiwake are monitored both from the sea and on land at their current remaining nesting site, on Gugh.  Whilst the Common tern are monitored wherever they choose to settle (if they do) both from the sea and on land.

Monitoring of our Terns took an unexpected but welcome turn; the cause of much excitement, for the Team, during June and July which also means that we can offer bit of a "poo-sandwich" in relation to the outcomes for these species.

Outcome: Fulmar surveys show that the numbers settling, at our two monitored sites, have been fairly consistent since 2006; however, fledging success has been quite variable.  Even so, Fulmar numbers are stable, on the whole.

All Kittiwake sub-colonies across Scilly have been counted annually since 2006. Over this time dramatic declines have been recorded, with the lo ss of 5 sub-colonies and a total breeding failure in 9 of the last 16 years.  Sadly this year was one of those years; although a small number of ittiwake pairs showed some initial interest in their one remaining site on the east of Gugh, no breeding attempts, or chicks, were recorded during 2021.

The big surprise came from our Common terns, who haven't successfully nested since 2017.  Despite arriving late to the Islands, a small number (18 pairs) settled and laid eggs in mid to late June on the south end of Annet (ordinarily nesting is expected to occur around mid-May).

Moving forwards: 

This year has been an exciting one not only in terms of how we survey our Seabirds but also in relation to what our Seabirds have been up to; and the best part?  There's still more to come!  Make sure you check back for part two!  Watch this space to discover how our other Seabirds have fared during 2021 as well!

For full details of of most recent whole Island Seabird Survey and the valuable conservation work that is taking place to support and protect our Seabirds please have a look at the Isles of Scilly Seabird Conservation Strategy (2018-2023) for the results of last years Seabird Surveys please read the Seabird Monitoring & Research Project 2020; the 2021 report is also available to read in full - Seabird Monitoring & Research Project 2021 technical report.  

Our Seabird Survey work is kindly part-funded

by DEFRA through the Isles of Scilly AONB.

Do remember that we rely on your support to continue our work.  If you have enjoyed learning about our work with Scilly's Seabirds, please Support Us and give what you can.  Thank you 💚

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