The Shags of Bass Rock

I’m going to revisit the theme of colour ringing in this blog and give you another example of how they are used in sea bird research.

Since 1973 the Centre for Ecology and Hydrology (CEH) have been running a long-term study on 5 species of sea birds that live on the Isle of May.  One of the biggest studies of its type in the world, the project involves using colour rings to follow individuals and learn about survival, breeding success and behaviour. One of the five study species is the shag. CEH colour ring over 90% of breeding shags and their off-spring every year on the Isle of May with the aim of establishing where they spend the winter. You can read more about the study here.

Now it might be hard to believe, but Bass Rock is not just home to gannets.  Look closely at the lower sections of the steep cliffs and rocky outcrops and you’ll spot kitiwakes, razorbills, guillemots, herring gulls, fulmars and the beautiful green-eyed shags.

On our first visit over to Bass this year, Beckie and I noticed a female shag (female shags hiss as they shake their heads at you, the males honk) wearing a colour ring breeding up on the prison wall. We couldn’t read the code at time as the ring was at the wrong angle, however the next day we got lucky …


White PSP breeding on Bass Rock – she has at least two chicks in the hole in the wall behind her

It’s not a great photo as I quickly snapped it on my phone but if you peer closely, or zoom in on it’s right leg, you can see it reads ‘PSP’. I excitedly reported the sighting to CEH through their dedicated email address ( and a week later got a lovely reply.

It’s turned out to be quite an exciting record as White PSP hasn’t been seen since she fledged from the Isle of May in 2003. I guess it’s no wonder if she’s been hiding in the prison wall for 13 years!

But our colour-ringed shag sightings didn’t end there.

I’ll save you the long story but on another visit we were locked out of the rock and had an hour to hang around the landings before we could get in. Just as we got settled on the path I spotted a shag with a red colour ring, on a ledge, just a few meters above the sea. I scrambled for my camera and quickly took a picture before it made the leap. It was Red LXA.


Red LXA just above the east landing on Bass Rock

Shortly afterwards by the south landing I spotted Blue AJX and later in the day Green AZE.

Again, I excitedly reported the sightings to CEH and got another lovely reply with details of where and when the birds had been ringed and of other sightings:

Green AZE was ringed as a chick on Craigleith in 2014. It made a trip over to the Isle of May in October 2014 but hasn’t been seen since.

Blue AJX was also ringed on the Isle of May in 2014, it was seen three times during the winter on the May and at St Monans in Fife but again, has not been seen since October 2014.

Red LXA was ringed as a chick on Inchmickery (another of the Firth of Forth islands just north of Edinburgh) in 2010. She was then not seen until 2014 when she had an unsuccessful nesting attempt on the Isle of May. In 2015 she returned to the Isle of May and raised three chicks. Earlier this summer she was recorded on an early nest but wasn’t seen after 9th May – maybe she fancied a change of scenery and that’s why she turned up on Bass in mid-July!

Finding out these little life histories of the birds you’ve seen is so interesting and rewarding and provides extremely valuable information for the BTO, CEH and other researchers working to understand more about the ecology of these birds. So keep your eyes peeled for colour rings when out walking on beaches or visiting seabird colonies and report your sightings!




Catching, tagging and measuring

It’s been a busy last few weeks collecting data from the Bass rock gannets.

As I’ve not had much time to sit down and write anything I thought that I’d just share some pictures with you.

When we fit a gannet with a GPS logger and altimeter, we not only fit it with two identification rings but we also take the opportunity to take some quick and basic biometric measurements from it. These measurements not only provide an indication of the condition of the individuals we are tracking but they will also allow us to look at relationships between size and behaviour.

The whole process from catching to releasing take no more than about 10 minutes and is documented in the photos below (taken on a number of different days!)

Click on an image to see a larger version with a description of what is taking place.


Meet B037

Meet B037, or 1446262 as I affectionately know him (1446262 is his BTO ring number)!

B037 in 2016. Photo Jude Lane

B037 was first ringed and GPS tracked in 2010. Although we tracked some immature gannets last year, prior to that all tracking had been of breeding adults as they are far easier to re-catch and remove data loggers from. As gannets don’t breed until they are at least 5 years of age we know that B037 was at least 5 years old in 2010.

Last year he was breeding again so we GPS tracked him for a second time. We also gathered flight height data from him. As you can see from the photo above, he’s back at the colony again this year although sadly it looks as though his breeding attempt has failed.

Tracking the same bird in multiple years is really exciting. The data gathered from the trips can tell us how repeatable individuals are in their foraging behaviour and allows us to compare their behaviour with others in the colony. We can also look at how behaviour can be affected by weather conditions and other environmental variables in different years.

Here you can see the tracks of B037’s foraging trips in 2010 (pink) and 2015 (blue).


We recorded 3 trips from him in 2010 and 8 in 2015. His trip durations were slightly longer in 2010 (25 hours average) than in 2015 (23 hours average). Corresponding with that, he covered a greater distance on each trip in 2010 (538 km average) than in 2015 (470 km average).

So this part of the data I am gathering and analysing again this year (I’ll blog more on flight height later in the summer). Hopefully I’ll be able to tag some of the birds I tracked last year so that I can see how consistent they are in how high they fly as well as seeing if they are going to the same places.

Who’s back?

Every gannet on Bass Rock that has been tracked with a GPS logger over the last 15 years has been fitted with two identification rings. A small metal BTO ring with a long identification number and a larger plastic colour ring with a unique four digit code. The metal rings are extremely difficult to read in the field but the colour rings are much easier, allowing us to identify which individuals are back without re-catching them.

You can read more about the reasons for ringing and colour ringing on the BTO’s site here.

Gannets are fitted with two identification rings, a metal BTO ring and a colour ring

Gannets are fitted with two identification rings, a metal BTO ring and a colour ring

The purpose of our first two trips over to Bass this season were to identify which birds are back, where they have established their territories and whether they are breeding or not. For Beckie Lakin, an MSc student studying Biodiversity and Conservation at the University of Leeds, this will add to the long term dataset on survival of breeding adults which she will use to look into the relationships between breeding success, foraging behaviour and survival. For me, it has given me a chance to see which of the birds tagged last year are back and what stage their breeding attempts are at in order to plan the first trip out to fit the GPS loggers and altimeters.

Beckie looking for colour ringed birds

Beckie looking for colour ringed birds

If you ever spot a seabird with a colour ring on it then it would be really fantastic if you could report it. The BTO has a reporting form here for any species and of course if you see a gannet with a colour ring then I would love to hear from you!



Back on the Bass

So after 9 long months I am finally back working on Bass Rock – and it’s bloomin’ brilliant!

We timed our first visit pretty well. According to Maggie Sheddan from the Seabird Centre, landing over the last few weeks has been pretty much impossible due to the unfavourable combination of swell and slippery landing steps.

There were no such problems this week though; some great skippering by Robbie Dale put us on the east landing on Monday afternoon allowing us to spend a fabulous 3 hours looking for colour ringed gannets in the sunshine.

I’m going to keep this blog really short. In my next post I’ll tell you why we were looking for colour ringed birds but now I’m going to leave you with this short film I made of Monday’s landing which captures why Bass Rock is such an incredible place to work (and yes, of course it’s always that sunny!)


World Seabird Twitter Conference – did you miss it?

The 2nd World Seabird Twitter Conference has been and gone but don’t worry if you didn’t manage to catch it live – you haven’t missed out. Max Czapanskiy (@mfczap) has done a brilliant job of making a Storify out of all the presentations so you can read through them at your leisure (and you don’t even need to be a Twitter user!).

Follow the link here and it’ll take you right there.

It was a fantastic event to be part of. Reaching over 2 million people across 6 continents it was a huge science communication event and a brilliant opportunity to share my research  on the Bass gannets with the seabird science community for the first time. A Storify of my tweets can be found here.

If you’ve been checking out the Bass Rock webcams and the Wildlife Sightings blog you’ll know that the birds are all back now and some are even incubating eggs. My work on Bass is due to start in a few weeks so I’ll do my best to post more regular blogs from June.


Bass Rock Gannets in the 2nd World Seabird Twitter Conference

Just a short post from me today about the 2nd World Seabird Twitter Conference taking place this week.


On Wednesday 14th April I will be presenting some of my work on three-dimensional gannet flight in my first international conference – via Twitter!

Twitter conferences are a fantastic medium, not only for enabling scientists to communicate and exchange information but also for providing a unique opportunity for the general public to find out about and engage with the work of scientists around the world.

It’s a really simple format: scientists will be tweeting about their work throughout the 13th and 14th April. Each presentation will take the form of 6 tweets over a 15 minute period. This year 71 scientists from 11 countries will be taking part. So if you’re interested in the work I’ve been doing or finding out more about other seabird research taking place around the globe, then be sure to tune in. And here’s how you can …

Already on twitter? Log in on Wed 13th and Thursday 14th April and follow the event with the hashtag #WSTC2. The first tweets will start at 11am BST (10am UTC).

Not on twitter? will be streaming all the tweets live so you can be a conference spectator without having to negotiate and learn a new social media tool!

I (@heyjooode) will be tweeting about my work with the Bass Rock gannets on Wednesday 14th April at 1pm BST (12pm UTC) – hope you can join me!

Other gannet presentations to check out are:

13th April

@Harriet_Clark_ at 10.45 BST (11.45 UTC) discussing the potential of new 3G GPS tags to provide information about important at-sea areas for a previously untracked gannet population

@v_warwickevans at 12.15 BST (11.15 UTC) on the potential impacts of wind farms on gannets in the English Channel

14th April

@JamesGrecian at 12.30 BST (11.30 UTC) talking about the differences in the foraging behaviour of immature and adult gannets (using data collected on Bass Rock last summer)

@BethanyClark36 at 12.45 BST (11.45 UTC) discussing her work on gannet sensory ecology using 3D tracking and accelerometry

It’s all about the Z’s and the W’s

In humans it is the combination of X and Y chromosomes that determine sex; females have two of the same sex chromosomes, XX, and males have two distinct sex chromosomes, XY. In birds it is Z and W chromosomes which determine sex but with the assignment the other way round to humans, females contain ZW sex chromosomes and males contain ZZ. It is the presence of these Z and W chromosomes in breast feathers, collected last summer, which I have been trying to determine these last few weeks at the NBAF Facility in Sheffield.

Working in a lab is a completely new experience for me and the complete antithesis of working on Bass Rock. The lab, as you would expect, is spotlessly clean, tidy, calm and quiet. Bass is noisy, smelly, dirty (filthy if it’s been raining) and a little bit crazy!


The process to get from feather to sex probably takes 3-4 days and involves 4 stages which I’ll attempt to outline below.

Firstly the DNA needs to be extracted from the feather. The end of the feather, or quill, which was attached to the bird, needs to be cut off and cut into tiny fragments. Working with small breast feathers requires a modicum of patience as small fragments of feather have a frustrating habit of pinging off if you fail to hold them down adequately!

Preparing feathers for DNA extraction.

A process involving the use of ammonia acetate is then carried out to leave you with a miniscule (so small you can’t see it with the naked eye) pellet of DNA in the bottom of a 1.5ml tube. To be able to assess and use the DNA it needs to be in liquid form and so is then dissolved in a buffer solution. There is a substantial difference in the quantity of DNA that you can extract from feathers and bird blood. This is because bird blood is nucleated and so contains much more DNA. The photo below of two 1.5ml tubes shows the difference.


The quantity of DNA in the sample can then be assessed using an agarose gel.


The next step is to run a PCR , or polymerase chain reaction, on the sample to see if it contains two identical Z alleles (male) or a Z and W allele (female). The Z and W alleles differ in size and this allows us to distinguish between them. A primer set that targets the Z/W alleles and an enzyme (Taq DNA polymerase) are added to the sample followed by a process of heating and cooling to three different temperatures. This allows the Z or W alleles to be identified and replicated millions of times. The Z and W alleles are then separated based on size using a DNA Analyser. The use of PCR in this technique means that even with a very small quantity of starting DNA, you can still get a sexing result.


Then it’s time for the exciting bit, it’s time to put the samples into the DNA Analyser and see whether my pipetting skills have been up to scratch and if ZZ or ZW alleles have been identified from the samples.

So after much pipetting and spinning down I have managed to successfully  sex all 40 of the birds tested, which is a third of the birds we tagged last summer. That might not sound very many but I’m quite pleased with how it’s gone especially given how much more difficult it is to extract DNA from feathers than blood. Apparently mouth swabs are also pretty reliable but we’ll have to see whether we’re brave enough to get any of those!


Finally I’d just like to say a huge thank you to Gavin Horsburgh and Deborah Dawson at the NBAF Facility (NERC Biomolecular Analysis Facility) who have both been incredibly patient with me and taken me through every step. Hopefully when I go back next year I’ll be a little more self-sufficient now I know what’s in store!




Who’s the daddy?

As you may have noticed the gannet research blog has been quiet over the last 6 months … the gannets left the colony at the end of the summer and I returned to Leeds to make a start analysing some of the data we collected. Until now there hasn’t really been too much to blog about, my days have mostly been filled with the joy and frustration of learning how to use a piece of very useful open source software called R which is integral for my analysis. However, for the last few weeks I’ve been enjoying a change of scenery working at the University of Sheffield.

What am I doing in Sheffield? Well, with another few months before I can get back out on the Bass to work with the gannets, I’m spending some time at the NERC (Natural Environment Research Council) Biomolecular Analysis Facility establishing whether the birds we tagged last summer were male or female.

Despite the fact that gannets, like many seabirds, are a monomorphic species (by this I mean male and females look identical) differences in their foraging behaviour have been discovered. Researchers from the University of Exeter found that male gannets from the Grassholm colony are more likely to forage off fisheries discards than females, whilst a recent paper published on the Bass Rock gannets demonstrated that female gannets make longer (in time and distance) foraging trips than males and that they are more likely to be associated with tidal mixing fronts. This is fascinating stuff but we don’t know the reason for these differences, especially considering the two genders are so physically similar.


So given that males and females look identical, how is it that we are able to undertake these sex based comparisons? Work by a number of authors in the 60’s, 70’s and 80’s suggested that the sexes could be told apart through a number of subtle morphological and behavioural differences. These included the colour of the head plumage, the colour of the web-lines on the foot, the collection of nest material and a behaviour known as nape-biting.



In 2000, these criteria were evaluated alongside DNA profiling from blood samples. The results of over 500 hours of observations at each nest found the only reliable non-molecular method for sex determination is nape-biting. It is only the males which will display this behaviour. You can find the paper here if you’d like to read more about what they did.


So we can reliably tell males and females apart by observing nape-biting. The only down side to this is that it only occurs when there is a change over at the nest. With foraging trips averaging around 24 hours in length you would have to live on Bass all summer in order to have a chance of observing this at every nest you are monitoring. This is why I am now in the Molecular Ecology lab in Sheffield learning how to determine sex using a DNA-based method.

If you’re interested, my next post will give you a bit more detail about the how we go about doing this.

Texting teenage gannets

So as promised in my last post, I’m handing over to Dr Jana Jeglinski from the University of Glasgow this week. As you’ll find out, it’s not just myself and the University of Leeds team that have been tagging immature gannets this summer. Jana has been doing the same, not just on Bass Rock but at a couple of other European colonies too. Read on to hear more about her exciting work.


Seabird colonies during the breeding season are a full-blown, multi sensual impression, if not impact, of movement, noise and, if you are (un)lucky to be close enough, smell. First your eye takes in everything at ones, birds swarming the sky around the colony like bees and clinging to cliffs literally everywhere. You give yourself time and you will see that this seabird city, this large entity is really made up by tens of thousands of individuals, pairs that work together to bring up their chick, shuttling to and fro from foraging grounds, bringing fish and nesting material, disputing with neighbouring breeding pairs and dealing vicious blows towards unlucky intruders into their miniscule breeding territory. You see some birds clustering at the fringe of this bustle, obviously not breeding, but peering with long necks around, and wonder what they are up to. You can spend hours just watching.

Colonies like this have long been thought to be separate entities, more or less likened to populations, with their own dynamics and their own characteristics. This is reflected in the design of many ecological studies, which are interested in aspects of the behaviour and ecology of breeding birds in one colony, or compare these data between different colonies. For most adult breeding seabird species, the concept holds true: once you have established your breeding territory you are likely to spend the rest of you life breeding in this colony, or trying to. For Northern gannets, we know that this segregation between colonies extends also to foraging grounds– adult breeders from different colonies are unlikely to meet each other during their foraging trips as the foraging ranges are highly segregated1. There is also a general understanding of high natal site fidelity – you are likely to breed in the colony in which you have been born.

A two-three year old Northern gannet defends itself against a neighbouring immature bird. Site ownership is still transitory in this age class, and both immatures might have left by the evening exploring other colonies.

The problem with the concept is obvious, but surprisingly hasn’t found much general attention to date: how do new colonies come about? And why do we observe young colonies to grow much more rapidly than their own production of chicks would allow them to2? The Northern gannet population offers a great illustration to these puzzling questions, having been exploited by large scale harvesting of eggs, chicks and adult birds for centuries, and having recovered since protection around 1900 from a population size of about 70.000 to more than 440.000 breeding pairs and from 16 colonies in 1900 to 51 in 2014 in their North-eastern Atlantic distributional range3.

The key to answering these questions is an almost completely overlooked age class in ecology: teenagers. We might know a lot about chick survival until fledging and about adult foraging strategies, but there is a gaping hole in our understanding of much that goes on in between. For a gannet the hole is big, covering four – five years, because gannets only start breeding at an age of about five tears or older. As it turns out, this gap is also very important for understanding seabird population dynamics. Information, e.g. from ring resightings and from a single tracking study4, shows that these young prebreeding birds spend the summer months investigating breeding colonies, the one in which they were born, but also others. We call this behaviour ‘prospecting’, checking out potential breeding sites and, first things first, meeting potential breeding mates on the way. A non-ecologists friends face lit up when I explained this aspect of the gannets’ ecology: “A gap year!”

Two 2-3 year old Northern gannets forming a preliminary and maybe lasting bond through ritualised ‘fencing’. Jana Jeglinski

A very long and influential gap year indeed, and one about which we have almost no direct observations and data. The relevance of these prospecting years lies in the decision making process that takes place during these years: where to breed. And with this one decision, taken by hundreds of thousands of first time breeding seabirds every year, ripened over the course of their prospecting years, the whole population can shift and change. A good illustration is the Norwegian Northern gannet population, which did not exist before 1946, because a few birds, amongst them chicks ringed at Les Etac, Ailsa Craig, Grassholm and other UK and Icelandic colonies5 decided to head east and breed on spacious Norwegian cliffs and not in their crowded natal colonies.

Not incidentally, I am specialised in and passionate about the ecology and behaviour of young animals, which is why I chose to investigate the prospecting behaviour and space use of immature Northern gannets during my Fellowship at the University of Glasgow. One of the reasons we know so little about this age class is their elusiveness – they might be spotted at the fringe of breeding colonies in so called club-sites, but take off at the least disturbance, or might catch our eye fleetingly out at sea, but that’s not much basis to an ecological study. For real insights into immature movement, we need advanced technology.

I am using GPS GSM tags, one of the cutting edge developments of biologging technology. These small electronic instruments can be programmed to collect GPS positions at predetermined times, and to store these positions amongst other sensor readings, for example flight height, temperature or salinity. They also have a solar panel to reload their battery so that I can deploy them for months at a time. What makes them uniquely suitable to my work is that they also transmit data: equipped with a sim card with roaming ability, they detect mobile phone coverage and send me the data they have collected using the mobile phone network. The reward for deploying these tags on immatures, by no means an easy task, is leaning back and receiving text messages from teenage gannets!

One of the study animals with a GPS GSM tag glued onto of the tail feathers with white TESA® tape. This deployment method is common practice and has been tested in many studies, showing minimal impact on the birds if the tags are lightweight enough. My tags weigh 37g, about 1.3 % of the body weight of the study animals – only half of the suggested upper limit of 3%. The dark top of the tag is the solar panel, which allows the tag to recharge its battery over the next few months. Tail deployed tags fall off when the birds moult their tail feathers, approx. 2 months after deployment.

I am currently working in three different gannet colonies in Europe, together with collaborators from the Centre for Ecology and Hydrology, the University of Kiel and the Research and Technology Centre Buesum in Germany, the University of Leeds and the University of Exeter. The Bass Rock, the largest gannet colony in the world6, is one of my study sites, with kind permission of the Dalrymple family and organisational support of the Seabird Centre, working together with Prof. Keith Hamer’s group from the University of Leeds. Keith’s PhD student Jude Lane (@heyjoode) and PostDoc James Grecian (@JamesGrecian) and I, sometimes accompanied by Maggie Sheddan, would travel out to the Rock, safely transported by Robbie and Jack Dale, spending the whole day helping each other capturing, taking notes and deploying tags – a great team working experience!  The Bass Rock is, through the sheer size of the colony but also the number of historical buildings on the island (now mostly occupied by gannets!) an amazing and literally breath-taking place to work.

Having long gotten used to side effects such as smell and dirt, I as most other ecologists, adore fieldwork and the deeply insightful bliss of being with and amongst our study species in their habitat. We usually settle with a somewhat resigned air back in front of our computers once the field season has passed. I currently find myself almost skipping to the office every day, brimming with excitement to connect to the server and find another data package received, another aspect of the hidden years revealed!

The year until next field season will see me analysing the tracking data of the immature gannets in detail, investigating the range of their movements and the frequency of their colony visits and why they might visit certain colonies but not others. The results of my analysis and more tracking data collected next year, will then allow me to integrate the network structure of the gannet breeding colonies into a model to understand better the drivers of the dynamics of the gannet metapopulation. We are also investigating a very applied question when investigating the space use of immature Northern gannet. We are looking into the overlap of immature gannet habitat use with anthropogenic use of their marine habitat, particularly offshore windfarms – a particularly relevant topic for the birds travelling to and from the Bass Rock and the German colony on Heligoland in the North Sea. My preliminary data already shows that immature birds use space very differently than adults do, and for a holistic understanding of the effect and impact of anthropogenic change to the marine environment it is paramount to include all relevant age classes.

To hear more about my work, you can follow me on Twitter: @JWEJeglinski

References and further reading: 1 Wakefield et al (2013) Science, 2 Moss et al (2002)3 Jeglinski et al. in prep, 4 Votier et al. (2011)5 Barrett & Folkestad (1996)6 Murray et al (2013) Scottish Birds