When the British Royal Society for Bird Protection (RSPB) set out to mark the razorbills, their aim was to track their behavior and movements along the North Wales coast. Tag data reveals that, at night, these seabirds spend a lot of their time idle at sea level. "We see this as an opportunity to reuse data and test whether birds might be swept away by tidal currents," said Matt Cooper, a graduate of the Masters in Marine from Bangor University in Wales. Apparently they, according to a new study led by Cooper who showed the potential to use seabirds to measure ocean currents. The results were published today in the journal European Geosciences Union Ocean Sciences.
Using seabirds to tell us about tides can be very useful for the marine renewable energy industry. Producing tidal energy requires detailed knowledge of current speed. Scientists and engineers traditionally measure currents using radar or attach anchors and buoys with scientific instruments. However, this guiding method is challenging and expensive. If marked seabirds can provide tidal data over a large area, they can help identify sites that will be a good source of tidal energy.
Superintendent Cooper at Bangor University learned of his interest in tidal energy and data collection, so they suggested that he look at seabird data collected by RSPB to see if it was possible to extract tidal information from it. Several years earlier, from 2011 to 2014, aRSPBteam had installed GPStags on razorbills in Puffin Island, North Wales, to study their distribution and breeding and feeding behavior. These black and white seabirds, similar to puffins and guillemots, only come ashore to breed. They spend most of their time at sea, looking for food or resting at sea level.
Data collected when the birds sit at sea level for hours is interesting in terms of bird behavior, but Bangor University researchers see other potential uses. "We took data that was discarded from the original study and applied it to test hypotheses in different research areas," Cooper said. "As far as we know, this paper is the first to describe the use of seabirds that are marked to measure any current," the researchers wrote in Ocean Sciences learn.
The non-invasive GPStags in the razorbills record their position every 100 seconds. With a series of positions and known time between them, scientists can calculate the speed and direction of the bird's movements. After sunset, the birds spend a long time resting on the surface of the sea, drifting passively with the current. "[At these times] their changes in position will reflect the movement of water at sea level, "Cooper explained.
At speeds of more than 1 meter per second, the average tidal currents in the Irish Sea region that researchers focus on are very fast, faster than razorbill that can row, but much slower than the speed that birds reach when flying. This means the team can filter the time when the birds fly. In addition, filtered data shows that, when birds roam, the direction of movement changes during low tide and high, when the currents in that area are expected to change from tides to currents and vice versa. Therefore, the team can ensure that they track the speed and direction of ocean currents rather than independent movements of birds.
Using seabirds to measure tidal currents has limitations. "We must remember that these birds behave naturally and we cannot determine where they go," Cooper said. But Ocean Sciences Studies show there is potential for this inexpensive method to provide important tidal information in a large area. By studying other marked seabirds, we can learn more about our oceans, especially in more remote areas where it is challenging to collect oceanographic data.
Cooper also hopes that this method can reduce the cost of producing tidal renewable energy, "which has become a barrier to this much-needed industrial development."
European Union of Geoscience. .