Marine iguanas look very primitive and rather repulsive to many people. Even Charles Darwin described the lizards as “hideous creatures” and “stupid and clumsy.” But if you spend a little time with these animals, it is hard to resist their fascination.
Marine iguanas (Amblyrhynchus cristatus) are the only lizards in the world that feed in the sea; they eat algae. These iguanas are found only on the Galápagos Islands, where they are endemic. Originally, it was assumed that the iguanas belonged to a single species, but Dr. Stefan Steinfartz from the University of Leipzig succeeded in proving that there are 11 subspecies of marine iguanas. The animals differ according to the habitat in which they live. However, what they all have in common is that they are classified as endangered by the International Union for Conservation of Nature (IUCN).
Black and yet colorful?
Male marine iguanas are generally larger than females. Depending on the island they live on, marine iguanas vary in size. A male on Genovesa Island weighs about 1 kg, while his counterpart on Isabela can reach 11 kg.
Their black color helps the animals warm up more quickly in the sun. The reason for this is that the cold-blooded marine iguanas, whose body temperature depends on the temperature of their environment, cool down considerably during their dives, which can last up to 45 minutes, when they bite algae off the rocks.
During the mating season (December/January), the males are brightly colored. This coloration depends on the habitat of the animals and includes a wide variety of red and green tones. It is believed that this depends on the color pigments of the algae that the animals eat in their respective habitats. However, the females are not impressed by this colorful spectacle; they choose their mate based on his size.
San Cristóbal is one of the oldest islands in the archipelago. Sebastian Steinfartz made a very unexpected discovery here with an international team from the University of Braunschweig: within a distance of just a few kilometers, two groups of marine iguanas have developed that do not interbreed and are genetically so different that they are classified as two different subspecies.
challenges posed by the habitat
Since marine iguanas live on the rocky coasts of the Galápagos archipelago, which are often very difficult to access, there is no comprehensive census of these unusual and unique animals. However, it is important to obtain clarity about their population sizes in order to protect them. Only then can conservation projects be developed to ensure the long-term survival of these primeval-looking animals.
Dr. Amy MacLeod and Prof. Sebastian Steinfartz from the University of Leipzig have been studying marine iguanas for years. They have launched a highly innovative and scientifically accurate project to count the animals. The marine iguanas will be counted using drones (UVAs), which are less expensive and less disruptive to the islands' hard-to-reach flora and fauna.
help comes from modern technology
In collaboration with local UVA expert Dr. Rivas-Torres and staff from the Galápagos National Park (GNP), the drones will fly over the coastlines of the Galápagos Islands from the ground or from boats to take photos and videos of the coastal landscape. This will cause minimal disturbance to the iguanas and other animals living there. Another advantage is that this type of counting is quick and inexpensive. In parallel with this new method, researchers will visit and count several colonies on various islands. The aim is to ensure that the drone count provides data that is as good as or even better than the previous methods.
Another innovative approach is that the images are then uploaded to a publicly accessible project on the globally available platform Zooniverse.org, where interested private individuals can participate in the count (crowdsourcing). (As soon as the new data is available, we will provide the appropriate link on our homepage). This gives people interested in nature conservation and science the opportunity to actively help/participate in a conservation project. It also gives them a feel for how time-consuming it can be to evaluate data obtained during expeditions.
This new form of counting has delivered impressively accurate results very quickly in the past and was also used in the pilot project carried out in January 2020 on the islands of Santa Fé and San Christóbal.
To ensure the accuracy of the counts carried out by volunteers, they are compared with those of specialists. The volunteers' counts are therefore only used to estimate the population size if they are sufficiently consistent with the counts made by specialists.
A better understanding of marine iguanas
The aim of this ambitious project is to gain a better understanding of the ecological needs of marine iguanas. At the same time, it also aims to provide new insights into the effects of climate change on their food availability. In addition, the census not only records marine iguanas, but also other animal species and environmental pollution. The photos will be used to create an extensive collection of image-based (basic) data about the Galápagos Islands. This will then form an archive documenting the current state of the islands, which can be used for conservation projects involving other coastal animals or environmental protection projects.
The team led by Amy McLeod and Sebastian Steinfartz hopes that the use of drones will greatly facilitate the determination of marine iguana population sizes and thus enable the timely development of a conservation management plan.
This expedition will also enable the further development of new surveying techniques for wild species and improve public understanding of conservation issues in the Galápagos Islands.
Help us!
Support the valuable work of Amy and Sebastian and help ensure effective protection for all 11 subspecies of marine iguanas to save these unique animals from extinction.