Marine iguanas are only found on the Galapagos Islands, but how many there are has so far remained unclear. A drone-based count, which also requires the help of laypersons, is intended to remedy the situation. In the citizen science project “Iguanas from Above”, volunteers can help to evaluate the drone images and count marine iguanas, but also other animals and plastic waste. At the same time, biologists have also carried out on-site studies of the endangered iguana species.
Marine iguanas (Amblyrhynchus cristatus) are the only iguanas that forage in the sea. The partly dark colored, partly colored animals dive to the bottom of the sea and graze on algae there. The world’s only occurrence of these marine iguanas is in the Galapagos Archipelago. Different subspecies, some of which can no longer be crossed, live on the various islands. However, it is not known how many of these endangered reptiles still exist. Many areas are difficult to access and a comprehensive inventory has not yet been carried out.
Marine iguanas census by drone
A team led by Amy MacLeod from the University of Leipzig now wants to change that. She has started two projects to better research the number and lifestyle of the rare marine iguanas. “Our ultimate goal is to produce accurate and detailed counts for each of the 11 subspecies,” says MacLeod. For this purpose, the researchers have used drones in recent weeks to photograph the habitats of marine iguanas on the Galapagos Islands from the air. “The use of drones makes many places accessible that were previously inaccessible,” explains the biologist. “He avoids boat landings on these remote islands, which – even when possible – is usually very dangerous due to the rough seas and sharp rocks.”
The aerial photos taken with the drones now have to be evaluated – and laypersons can also help with this. In the citizen science project “Iguanas from Above” it is necessary to look at the recordings and count the marine iguanas in them, but also other species such as Galapagos sea lions and various seabirds. “This would allow us to evaluate our data faster in the future, repeat population size surveys more often and finally monitor this endangered species properly,” says MacLeod. The data obtained in the volunteer project should also help to create a training set of images and counting data for an artificial intelligence capable of learning. It could then help in the future with the evaluation of such aerial photographs.
More insight into threat
“It will take a while to count the iguanas from the pictures. However, we have already seen that the marine iguana subspecies found on Marchena Island appears to be much rarer than expected,” reports MacLeod. This finding is important from a nature conservation perspective. On other islands such as Darwin and Wolf, however, the number of marine iguanas is still largely unknown. “Because these islands are rarely visited by researchers and catching iguanas there is very difficult, they have not been sampled very often in the past and have therefore remained quite mysterious,” explains the biologist. In addition to the aerial photographs, she and her team collected blood and skin samples from iguanas and algae from their habitat in order to gain more insight into their diet.
Also part of the counting project is the question of how badly the beaches and land areas of the Galapagos Islands are polluted with plastic waste. “Because we were concerned and could see the plastics clearly in our images, we reached out to other researchers to work together on using our drone images to study plastics,” explains McLeod. Plastic waste should also be counted in the Citizen Science project. Knowing where the plastic comes from and where it ends up is important to addressing both the source and the outcome of the problem, the researcher said. The data will also be used for targeted cleanups that remove plastic from places where it threatens wildlife. In addition to the plastic waste, more and more people and animals that have been introduced are endangering the rare marine iguanas on the archipelago, and there are also pressures from climate change and an oil spill.
The project “Iguanas from Above” is also on the citizen science platform Zooniverse to find.
Source: University of Leipzig