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| A view north along the west coast of Lundy (c) Tom Dickins |
The island is ideal for observational animal behaviour work as it is home to many species. This year the team visited from 25 June until 9 July and this enabled us to look at breeding bird populations as well as some of the resident mammals (Soay sheep, feral goats, and Sika deer).
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| Sika seen through Soay in Middle Park, Lundy (c) Tom Dickins |
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| Guillemots on breeding ledges in Jenny's Cove, Lundy (c) Tom Dickins |
We only brought three students with us this year, compared with our normal ten or more, as I am redeveloping the trip with colleagues for a full launch in June 2014. However, I had promised these students that a trip would run for them and so it did. It also gave me an opportunity to plan projects for the new version of the trip so I spent much of my time, when not with the students, going from site to site and taking field notes for future work. I also had the opportunity to have a couple of very fruitful meetings with the warden and the island manager.
One student was doing a final year project for her BSc in psychology (UEL). She decided to work on Soay movements and collected data about all ram groups. Her core concern was to try and identify possible phenotypic markers of dominance (horn thickness and testicle size were among her measures) and use this to predict how group decisions to move foraging patch worked. In short, she wanted to know if these features consistently predicted the first to move. Whilst on the island she trailed a number of ram groups, took photographs and also filmed their behaviours for later coding back at the lab.
Our MSc student (Brunel) was running a foraging experiment on interference and ideal free distributions with sparrows. She was much helped by the University of Sheffield team (my alma mater I was pleased to note) who have been running a study on the Lundy sparrows for many years now. She was effectively replicating a study by Cheryl Johnson, which is available at this link, however we hope to collect more data from other passerine species in Essex and London.
Finally, our PhD student (Middlesex) was field testing a puzzle box for herring and lesser black backed gulls. This box is designed to test gulls' exploration and learning in urban, coastal and offshore areas. His principal interest is in urban gulls and possible behavioural and cognitive differences that enable them to survive in an urban ecology foraging for anthropogenic food sources. The field test was hard work, but yielded some data. The notable effect was that gulls began to explore the baited puzzle box when it was placed nearer to human habitation, suggesting an already learnt association.
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| A fledgling Wheatear on a path in Middle Park, Lundy (c) Tom Dickins |
Whilst on the island I became interested in the Wheatears. This was due to a comment from a colleague. He had noted the adults hopping along the path in front of him, emitting bursts of a chat-chat-chat sound terminated with a more high pitched note, which to him sounded like a juvenile. He wondered if this sound were a part of the general behaviour to lure predators away from nestlings.
I was uncertain of this so I devised a quick walking study that would enable us to collect data on Wheatear behaviour as we moved around the island, as there were many to be found. The basic conceit of the study was to count chat bouts and high pitched note bouts under three conditions after engagement by a Wheatear - continuous walking, stopping for ten seconds and then walking on, and stopping for twenty seconds and then walking on. All walking would continue along the path in the original trajectory. Later we perhaps could add in moves off track etc. But this simple study would perhaps uncover a pattern as we altered the potential threat level we presented. I devised a checklist:
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| Extract from my field notebook showing Wheatear study plan. |
From my initial observations it seemed that Wheatears would only emit the high pitched sound occasionally, and then it tended to be as they would suddenly fly off at a right angle to my trajectory and into scrub. However, this pattern began to break down in the second week and I soon realized why - their chicks had fledged and left the nest. Now the adults were all over the place, engaging us differently and less predictable to the casual observer. So, the study became a little disjointed. None the less, it has given me something to think about for 2014.
Many more observations could be related - about sea birds, peregrine behaviour, ravens, seals, and invertebrate life but blogs should not be too long.
Next year will see a mixed group of ecologists and behavioural scientists tackling a variety of projects and I am very excited by this prospect.
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| Sunset off Lundy, seen from 'the secret pond' (c) Tom Dickins |
Having now reviewed my limited data collected from Lundy, the commonly recorded 'chack-chack' call of the Wheatear appears more frequently heard when the bird is stationary, or more than approx 25 metres away.
ReplyDeleteThe 'chack-chack-tweet' sound (the subsequent 'tweet' being more high pitched and what was perceived to be the juvenile sounding note)is made by male and female adults, and is heard more frequently when they were in flight or within 20-25 metres of the researcher.
I note that one author of a bird identification guide suggests that the 'plaintive tweet' following the chack-chack call is emitted when the bird is anxious.
It is interesting that another pattern emerging from the data was that chack-chack-tweet was heard more frequently when the observer was alone than when in pairs or groups. This may be because pairs and groups of researchers provide more warning of their presence and, speculatively, were therefore less likely to be spotted for the first time within close proximity to the nest.
The plan for next year will be to set up a study exploring the relationship between various calls and the motion of the Wheatears - motion on the path ahead, flight trajectory and visual flashes of the distinctive tail pattern.
Some planning to do before June 2014.
This is interesting. We will need to make sure the notion of anxiety is not too anthropomorphic in its use. I am sure there are internal states at play but perhaps not rendered in quite the way we imagine our intentional psychology. So, we might expect and increase in this behaviour across the season, such that egg guarding, chick guarding and fledgling minding might all see different frequencies of these behaviours. And, as you say, the number of individuals approaching as well as the formation and direction they approach in could all have an impact.
ReplyDeleteIt is possible there are individual differences here also. Some wheatears will be more bold - something that is much discussed in the animal personality literature - and this might be part of a behavioural syndrome. So, more observations are also needed.