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Post date: Jul 16, 2014 2:15:48 PM
With the majority of the razorbill and guillemot chicks now on their way out to sea having taken the plunge from the cliffs of Puffin Island, you could well be forgiven for thinking that the season is at an end. And for most of the birds it is. In addition to the razorbills and guillemots, the shag chicks have also left the relative safety of their nests and are to be found congregating at the water’s edge, learning to forage and getting used to the notion of flying. The remaining gull chicks are also taking to the air, with the greater black-backed chicks already looking rather formidable. The majority of the kittiwakes, however, still have a way to go yet before their breeding season is done.
The kittiwakes are the latest of the breeding seabirds on the island, with chicks only having started hatching within the last few weeks. Personally it’s the time I've been eagerly anticipating, as even though I am monitoring kittiwake breeding from laying to fledging, now is the time my workload (and stress level) is amped up as I deploy data loggers on some of the breeding adults.
As with the razorbills and guillemots which were focused on earlier in the season (by Steve Dodd, RSPB), we deploy GPS loggers on kittiwakes to identify their foraging distributions during this period. As much as I could write about these devices, the maps which can be almost instantaneously generated upon their retrieval defy the need for long-winded waffle on my part (cue a collective sigh of relief). See below.
Example GPS tracks from two kittiwakes this year.
Even though maps generated by the GPS devices float my boat (and are a big part of what got me hooked on all this bird science), my main focus is on deploying accelerometers. These devices take a tad more describing as the data collected are less intuitive to interpret, but in my opinion they offer up equally fascinating insights into the at-sea (and also at-colony) behaviours of these birds. Accelerometers record movement across three axes (up-down, side to side, back-forward) which can ultimately be used to work out the behaviour of the birds for the duration of the deployment. These devices also confer the advantage of recording at high temporal resolution (I set mine to record 25 times per second), allowing identification of finescale features such as individual wing beats and short lived foraging bouts. Below is an example of how I interpret these data. As it stands, I'm reaching the end of deploying and retrieving these devices for this year, so I have a fair amount of data analysis to get cracking on with. The accelerometry data I've collected will be interpreted in relation to other behavioural data (from time-lapse cameras) as well as morphological data(I've been taking a range of other measurements from the birds throughout the season). The aim is to examine if and how such behavioural and morphological measurements relate to each other, as well as how they relate to individual breeding success. Wish me luck...
Example accelerometry data from kittiwakes. The heave axis relates to change in vertical acceleration (mostly from flight). The pitch denotes the angle of the bird, and salt water immersion is recorded by a separate device on the birds leg.
For those keen to read more, further information on how I am interpreting the accelerometry data can be found on a poster I present at The Seabird Group conference earlier this year. Available here.
Away from my project, there have been other goings-on on the island, mostly in the form of ringing days by the SCAN ringing group. All three scheduled ringing days for this year have now been completed, with chicks from all of the more abundant seabird species breeding on the island having been fitted with uniquely numbered metal rings. Unfortunately I could only make the last of the ringing days, which focused (rather aptly) on kittiwake chicks. A fair number of chicks were ringed, however this year is far from being a great year for kittiwakes on Puffin Island (although it is nowhere near as poor as last year). I’ll be able to say more about this when the chicks (hopefully) fledge!
Other species were also paid their due attention on the ringing day, or rather more than their due attention in the case of the puffin caught and ringed much to the adoration of all involved (myself included, although I hate to admit it). There currently aren't too many puffins on the island (~30 breeding pairs being a high estimate), so catching and ringing one is a bit of a break from the norm. It also gives me an excuse to include a photo of a puffin on here; a shameless way of generating more page views.
The Puffin caught on the last ringing day.
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