College of Science Postgraduate Seminar Series 12th August 2014

College of Science Postgraduate Seminar Series - Summer 2014 

12th August 2014 - 1pm - Zoology Museum (Wallace)

Talk 1

Harbour seals (Phoca vitulina) at sea: Exploring area usage in a central place forager.

William Kay

(Masters student, Swansea University, UK)

Central place foragers such as harbour seals inherently display tendencies to return to fixed areas for a variety of reasons including pupping, moulting and resting at their chosen haul-out sites. Despite this need to return to a fixed location, individuals regularly forage over extensive spatial and temporal scales, spending many days at sea and travelling upwards of 60km offshore. 

Optimal foraging theories suggest however that these movements are not limitless and instead, are restricted due to physiological and energetic demands. Thus, classifying and quantifying areas of importance for these organisms is crucial, for both increasing our understanding of their general behaviours and identifying locations where anthropogenic activities, such as off-shore renewable energy or commercial fisheries, should be conducted with particular care. 

Visual tracking of marine mammals at sea is virtually impossible because they spend such a large majority of their time underwater. Most previous studies are primarily based on VHF and satellite-tracking telemetry, both of which have their limitations in accuracy and transmission. This research uses the recent, preferred technique of dead-reckoning, to fix GPS locations at 5 s intervals in order to examine the fine-scale movement of harbour seals at sea.

From these data we hope to attain information about the paths that individuals take in the Wadden Sea, such as overall track lengths and track tortuosity to identify hotspots for foraging activity. The energetic costs of movement at sea are also considered in an effort to describe behaviours according to novel techniques.

Talk 2

What can accelerometry tell us about soaring flight?

Hannah Jane Williams

(PhD student, Swansea University, UK)

Accelerometry has been used to identify behavioural patterns through the quantification of body posture and motion for a range of species moving in different habitat types. The use of acceleration data to quantify different flight modes, e.g. soaring versus gliding, is however more problematic, as changes in acceleration may also arise if a bird is “pulling g”. This study uses Daily Diary tags, with tri-axial accelerometers, to collect high-resolution data on the flight performance of the Andean Condor (Vultur gryphus), a soaring species that relies on slope lift and thermals to gain height to search of resources. Unlike many of the accelerometer devices used in the study of animal movement, these tags are also equipped with tri-axial magnetometers and pressure sensors, allowing flight to be categorized into gliding and soaring, and the nature of the lift (i.e. thermal or wind-driven) to be identified . We examine patterns in bird posture and vectorial dynamic body acceleration (VeDBA) specific to different phases of flight and so devise a classification tree to allow others to identify these using accelerometry alone. We investigate to what extent information can be extracted from accelerometry regarding soaring performance, including parameters such as bank angle and glide speed.