Storm Petrels of 2023

Wind and rain inflenced our ringing activities more than our AI precautions did. In the end we 'lost' two nights and spent two nights on the beach - to avoid the wind. We only managed one night on what is one of our more productive sites.

To cut a long story short our captures were the worst on record for over a decade. Having taken, and expected to use, a large number of the 2500 rings taken we only managed 152 new birds, 9 UK recaptures and one Norwegian ringed bird! In any previous year we would have caught this number in a couple of hours.

Night-time ringing station

Ringing storm petrels and taking biometrics and photographs

Our capture rate was typical of other sites around the UK. The Welsh coast, other parts of Scotland, Devon and some sites in Ireland were recording lower capture rates - in one instance in Devon a night of nothing at all! 

Why was this? Obviously the first thing that springs to mind is AI (storm petrels being essentially pelagic may hide mass deaths at sea), however some live sampling of petrels at Mousa returned that all were negative for AI. The next option is the reported and unusally high sea temperatures. The thinking here is that the food source of plankton/krill is considerably further north in cooler waters and that petrels staying with their food source are then much (much) further from land precluding succesful breeding. As such many have not attempted breeding and are therefore not coming to land (to be caught). Let's hope this is the case, next year may be able to answer this question.

However, out of this the lower catch rate there were other benefits. Currently we are trying to build a mechanism for being able to sex storm petrels (nearly all are not). So, with lower numbers, we were able to take a full set of biometrics, photograph, examine for brood patches and take feather samples (under license) on virtually all birds to collect data which may eventually lead to guidelines for phenotypically assigning sex to storm petrels.

An envelope containing plucked feathers and an underwing photograph of the same bird to determine the extent of underwing 'white'.

The Team this Year.

James, Ailsa, Lydia, Liz, Rachel

Sophie, Bob, Peter, Steph

(missing Julia, taking the photo, Tanya and Lora)

With thanks as always to Jean and Andy for transporting us to/from the island.

2023 - a return.

 Following our enforced absence last year - due to all ringing activities being suspended due to Avian Influenza - we managed to get on site this year. It came with caveates though - Nature Scotland said there was to be no ringing of Great Skuas (they have been hard hit by AI), and we had to implement a biosafety procedure to ensure we didn't exacerbate any AI issues. 

That said twelve of us made the journey north to continue our long-term ringing project and this year, besides ringers, we invited along several Wildlife Conservation /Entomology students. 

On the island itself not much was different regarding the houses - a few walls had lost some stones and a few more roof tiles had dropped off. Elsewhere though the weather had created some bigger changes. A new gully to the sea had 'opened up' on the western edge, with much peat-slippage elsewhere, and a large section of rock had broken away from what we call the Slab-Wall (NW corner of the island) to create additional access to the rock face. 

The new gully

The island was 'wet' this year with lots of running streams and large pools. 

Wandering about there were the typical dead Greylag Geese - youngsters taken out by the skua - as well as the requisite number of suicidal sheep (there are about 200 sheep on the island). Checking the island for signs of AI before ringing we discovered only one dead guillemot, one kittiwake and one puffin. There were 'bits' of puffin, fulmar and other seabirds, all within what we would have expected to find. 

Besides ringing storm petrels, see next post, we undertook our usual whole-island fulmar census (numbers slightly down) and did seek out skua chicks (without ringing) to determine what level of breeding had taken place (adult numbers on the island were down by about 70-80%). We also confirmed breeding of Greater Black-backed gull, Herring Gull, Fulmar, Shag, Cormorant, Guillemot, Ringed Plover (2 pairs), Meadow Pipit, Wren, and Oystercatcher, and suspected breeding of Rock Pipit, Rock Dove, Pied Wagtail, Kittiwake and Arctic Tern.

The nine Great Skua chicks found on the island.

With our students we increased our understanding of the island by undertaking Phase 1 and Phase 2 habitat surveys, took soil samples, performed a series of botanical quadrants and started a species list for invertebrates on the island. Unfortunately we did not undertake any moth-trapping this year. 

Although generally a week interrupted heavily by wind and rain we did have a couple of more typical days.

A series of recaptures

These just in - a series of birds all initially caught on Nan Ron and then recaught several years later back on Nan Ron (possibly indicating all are on-island breeders). We made all of the original captures over several years, Stefan made all of the recaptures over 7-8th July 2021.

Figures show - elapsed days between captures, d, and then the (year) of initial capture. x(number) indicates a similar number of birds, two, three, and four, of same elapsed time.

5099d (2007), 4362d (2009), 4006d (2010), 3269dx2 (2012)

2900d (2013), 2898dx2 (2013), 2897d (2013), 2158d (2015), 2157d (2015), 2156d (2015)

1444dx2 (2017), 1443dx2 (2017), 1801d (2016),1061d (2018), 1060dx2 (2018), 1059dx4 (2018), 1058dx3 (2018).

An early July visit pulls in a lot of retraps! Pencil that in for 2023

David Scott PhD thesis

 David's PhD thesis is often quoted by anyone who writes about Stormies. At the time David did not have the time to publish any papers from his thesis and the thesis itself was 'old-school' i.e. still on paper so, for most, unaccessible. Over recent months Oxford University has scanned David's thesis and David himself has made it widely available to anyone who wishes to download a copy for free.

It is available at: https://ora.ox.ac.uk/objects/uuid:24973c21-ab78-42f1-a3c1-a7665b776bbf

Note that it is 35Mb in size (something like 300 odd pages).

A late recovery from this year

2757508 ringed on ENR on the 11.8.2021. was recaught at Score, Highland Region, seven days later having traveled 154km - a mere 22km a day, which is a dawdle by stormie standards.  

End of year bits...

Four stormies we caught on Nan Ron in August have now come back as new ringings all performed in July - so not really that interesting other than that they are still around after a month. We managed to add to data by sexing and aging two as 6Fs.

The Great Skua we resighted by colour-ring was a juvenile bird of this year too, and the one found dead, alongside the dead Greater Black-backed chick were also of this year.

A flood of recoveries

 Many recoveries we get of birds caught and/or recaptured on Nan Ron come about by the contribution of others. To date 46 other permit numbers have contributed to retraps or controls, from individuals to partnerships, ringing groups or observatories.

This flurry of recoveries is a combination of our work on Nan Ron and the work of the Bache, Shearwood and McShane Ringing Partnership (now Belvide RG) and Stefan Bodnar. Fifteen other permit numbers have been responsible for other ringing or recaptures of birds reported here.

This post reports seventy-seven birds caught and recaptured on Nan Ron. The four oldest were greater than 14 years old (5837, 5458, 5111, 5103 days between ringing and recapture) while another four were greater than 11 years old. The graph shows the time elapsed between ringing and recapture of these 77 birds. Twenty-two birds were within year retraps while 28 were recaught approx two years after ringing.

Two birds ringed this year in July were recaptured elsewhere: one at Fair Isle BO (19days and 189km later) and one at Score, Highland Region (10days and 154km later).

Thirty-one birds ringed elsewhere were recaptured (controlled) on the island. These ranged from seven birds all recaptured within a year from St Johns Point, Highland Region to one originally ringed on Priest Island 5867 days previous (c15 years). An interesting movement is abird from Collieston, Aberdeenshire to nan Ron, 196km in two days (although this is well within reported foraging distances for Storm Petrels). Any birds caught with an elapsed time of >1000days between ringing and recapture could be considered to be local breeders.

Note also the one bird from Cork, we don't get that many movements from Ireland, and one bird originally ringed on Skokholm in 2019.