Aarhus University Seal / Aarhus Universitets segl

Drone technology

Drones for use in research and consultancy are constantly being developed, and tools are adapted to the tasks. We continuously develop and refine our technical equipment so that it matches the needs. We use both flying and diving drones for photos and video, and images are put together as required.

Here are some examples:


Marine mammals

Observations and measurements of marine mammals can be challenging, e.g. because they spend a lot of time under water, are located in inaccessible places and can be difficult to find. Among other things, we use drones for behavioural observations, counts, measuring animals for age determination and assessing the condition of their bodies. This information is important when, for example, studying how human activities affect the animals ' behaviour, habitat use, breeding and foraging success or energy consumption.

In addition, the drones have also become an important part of the inventory in connection with tagging seals. Here, they are used to examine the bottom conditions prior to catching and thus increase safety and the chances of successful capture, as well as to monitor and reduce the time that trapped seals stay in the nets.

Birds

We use drones as a supplement when monitoring breeding bird colonies and performing more detailed counting of certain migratory birds, where we can get close without disturbing the animals. The images can then be analysed when we return home.

This photo is taken from the drone in Nørreballe Nor at Sydlangeland on 15 January 2021 and shows flocks of freshwater diving ducks (tufted duck, pochard and greater scaup). The recordings were subsequently used to look at the age and gender distribution of particularly the greater scaups in the flocks. This information is important in order to understand the population dynamics of the species. In this context, it is particularly interesting to be able to study the number of juveniles produced a given year, i.e. the species ' reproductive rates. Previously, we have, to some extent, received this information from wings that hunters have submitted from hunted birds.

Contacts

The Arctic

In the Arctic, we use drones e.g. to assess the marine vegetation in the shallow waters along the coast. As there are great tidal ranges in different areas, it is advantageous to record the images at low tide, where the tidal vegetation is laid bare and the submerged vegetation is also more visible (see the image). Drones are also used to quantify the size of icebergs, which also makes it possible to calculate the melting of icebergs over time. We use flying drones and diving drones (ROV) in our work.

The drone images here are recorded at low tide, and the mosaic shows the tidal vegetation as a small brown strip along the coast, while submerged seaweed appears as brown fields/patterns in deeper water in the bay.

Thermal camera

A drone with a thermal camera can, for example, be used to monitor deer game and to record outflowing groundwater and metabolic turnover in washed up seaweed. For example, a publication has been issued: Issue 169. Brug af drone med termisk kamera til overvågning af hjortevildt (au.dk)

Contacts

The photos here are taken by a Marvic 2 drone with a dual camera, which can switch between a thermal and photographic camera. In a lake near Viborg, a rubber boat with a diver is seen a few metres to the right of the boat on the photographic image. When water is cold (below 4 degrees), it is coldest at the surface and warmer at depth. This is a special characteristic of water, which means that ice settles at the surface. The thermal camera reveals that the boat has stirred up the water during the voyage, as water behind the boat and the diver has become a few degrees warmer than the rest of the lake's surface (see the red stripe). In addition, the red area along the edge of the lake indicates that seepage of groundwater or perhaps another inlet of water is slightly warmer than the lake surface.

3D technology

3D technology from drone recordings has been used, for example, in mapping algae blooms. The animation is from Skive Fjord recorded in May/June 2019. Read more about this.

Underwater camera

For instance, a drone equipped with an underwater camera has been used in a project that mapped the prevalence of eel grass. The illustration to the left shows how the drone flies to a position that is programmed in advance, lowers the camera and takes a picture. The images were then merged into a mosaic to create the picture shown to the right, which could then be analysed.

Above are images from a single immersion from drone and camera, respectively.