Over the last couple of months I have had a busy whirlwind of deploying noise loggers; learning how to program recording schedules and then process acoustic data; complete health and safety forms; obtain permits for area use; train volunteers for visual surveys; organise fieldwork shifts… and this is before the fieldwork has even started! But now it’s all underway and the data is coming in!
Eavesdropping on Dolphins…
Back in November 2013, three noise loggers were deployed in the Swan River as part of my PhD project examining the acoustical and behavioural response of coastal dolphins to noisy environments. I have been lucky enough to have great support from the students and staff at CMST to help me with deployments. Now the first batch of acoustic data from this first logger deployment is in my office, ready for processing!
These noise loggers record underwater sound produced by ambient (wind, waves), biological (dolphins, fish, crustaceans), and human sources (vessels, traffic, and construction). For more info on these noise loggers, see my previous post on recording whale sounds in Albany. Whilst I am examining this first acoustic data batch, the noise loggers have been moved to new locations and are busy recording more underwater sounds.
Over the next year, I will be deploying noise loggers at several spots throughout the river. I can then use these data to describe the underwater soundscape of the Swan River and examine the vocal behaviour of bottlenose dolphins.
… Whilst Watching from Above!
Visual observations of dolphin behaviour began in January 2014. I am conducting visual surveys at various vantage points along the shoreline, using a theodolite to record dolphin movements and behaviours in the river. This visual information can then be used to understand the context of dolphin sounds and their use of the underwater acoustic environment.
A theodolite is traditionally a surveying instrument, used to create 3D models of the landscape. It does this by selecting different points, then measuring the horizontal and vertical angles to give an exact bearing and distance to each point; this creates a scale map of the area. But we can also use this technique to get the position of objects out at sea – such as dolphins! So we can use a theodolite to map a dolphin’s position each time it surfaces, giving a very fine-scale track of how the animals are using an area. The added bonus being that the dolphins are not aware of our presence, so we do not have to worry about disturbing the animals and influencing their behaviour. Although I do often wonder if they have a “feeling of being watched”…
To run these visual surveys, I require a theodolite team: one person entering data on the computer, one collecting positions using the theodolite, and some others to find the dolphins! Thankfully, I have had an overwhelming amount of support from my ex-students (and some marine biologist friends), and currently have around 25 volunteers donating their time to help out in the field. Many are studying or working full-time, making their contributions all the more amazing and appreciated!