Despite the amount of species and sights I have described in
my previous blogs on Iceland I spent the majority of my time there working on
the LOMVIA project; a study of Brunnich’s and common guillemots by BAS and its
partners. More details can be found here but I will explain it briefly:
As climate change impacts the oceans via warming
temperatures the distribution of species alters. This has been noted in the
movement of prey fish species, such as sandeels and capelin, whose distribution
changes can disrupt seabird populations.
As prey species distribution changes the distribution of
seabirds may change as well, causing competition between species that wasn’t so
prevalent in the past. The LOMVIA projects aims to ascertain if there is any
competition caused between two closely related species – the common guillemot
and the Brunnich’s guillemot – brought about by these changes in the
environment.
Common guillemots are a temperature species; spread across
the North Atlantic and North Pacific they live in areas closer to warmer waters
but do range far north to places like Iceland and Norway. Brunnich’s guillemots
are a colder water species, preferring the temperatures of the Arctic and so
have a more restricted range. But the two species do overlap in areas where
warm and cold ocean currents pass each other and mix – this is very noticeable
in Iceland and our reason for being here.
Spot the Brunnich's! |
The study we conducted collected a lot of data, focusing on
where the two species were foraging for their food and what they were eating.
We collected the data in a number of ways, predominantly through tagging work
and diet observations; but first we had to find suitable locations to work in.
A guillemot colony on the edge of a heavily populated puffin area. Some work could be carried out here but another location was better. |
The main common guillemot study ledge on Papey, birds were accessible for deploying tags and observations of diet - a perfect combination. |
The tagging work consisted of deploying devices on the birds
for a short period of time. These devices are carefully attached to a few
feathers, can be simply removed and are incredibly light – all so as to not
harm the bird in any way.
We utilised two types of device: GPS and TDR (time-depth
recorder). The GPS tells us where the bird is and the TDR tells us its depth in
the water. More specific information can be gleaned by combining the two on one
bird, thereby establishing its behaviour along the entirety of its journey from
the colony and out to sea to fish.
TDR attached to the belly so as to be in contact with water more often, GPS attached to the back to map the constellations. |
Each bird was given a unique mark; a coloured shape on the
GPS tag, which was repeated on a bit of tape covering a few feathers on the
head. This head flag allowed us to see which of our birds were present in a
busy colony, even if the tags themselves were not visible, so we could watch
their behaviour and recover the tags.
Once the tags were removed from a bird the head flags
remained so that we could identify individuals we had already studied and so
did not bother them again later in the season when deploying more tags. If we
were unable to recover a tag the birds would gradually preen them off anyway,
in this way no bird was left with devices on it after a week.
The tagging work was one main focus, the second was diet observations.
Studying diet is primarily done by direct
observation; then, by combining such observations with the tagging data we get a fuller workup of
what the birds are doing away from the colony. The adults bring a whole fish back to their chicks in their beaks. By
watching the colony the species of fish can be identified as we watch the
adults bring back a meal. Each fish has its own characteristics that we look
out for.
By being able to observe the birds we were working with we
could at times get a full dataset for one individual. The tags tell us where
the bird went and when and how deep it dived, and the observation of it bringing a fish back to the chick tells us what it
caught on the last dive it did in the foraging trip. So much vital information
in understanding the ecology of these birds for conservation purposes!
By ascertaining the foraging range and diet of the two
species we can determine if the distribution of the temperate species – the
common guillemot – is altering as the seas warm and, if these changes are
occurring, are they causing clashes with the arctic species – the Brunnich’s
guillemot.
Initial results are interesting but for that information you
will have to watch out for publications from the LOMVIA project over the next
year or so. For now though, it was a privilege to be involved in a study at the
forefront of this area of research, with a great team in a stunning country.
And of course, working with such amazing birds is always the highlight!
The chicks fledged at the end of the season and hopefully they continue to grow well! |