Because of local crested newts: The celebrities of our domestic amphibian world are more enthusiastic about hiking than previously thought, shows a study. In doing so, they are apparently specifically looking for the best ponds for reproduction in their region. This may also apply to other amphibian species, say the scientists. The results thus contribute to the understanding of the ecology of these animals and can benefit the applied protection of special species.
With their serrated back crest, they look like little dragons – in addition to this characteristic of the male, the northern crested newt (Triturus cristatus) also the length of up to 18 centimeters to one of the most spectacular amphibian species on our doorstep. The amphibians belonging to the salamanders occur in and around small standing water bodies in almost all of Central Europe. As is typical for amphibians, they alternate between water and land: adult crested newts are often out and about in ponds, but also hunt on land and usually spend the winter there under stones or moss. However, they are dependent on water for reproduction and are therefore found in the ponds during the mating season.
Great crested newts are strictly protected in Germany because in many places their populations are in a critical state of conservation. Like other amphibian species, they mainly suffer from the changes in their habitats caused by humans. A research team led by Sebastian Steinfartz from the University of Leipzig has now devoted a study to the crested newt. “In order to counteract the current worrying decline in amphibians and to develop suitable protective measures, it is particularly important to better understand the behavior of amphibian species in their natural habitats,” says Steinfartz. Specifically, the scientists dealt with the investigation of the individual migratory movements of crested newts in their local areas of distribution.
On the trail of spatial dynamics
The focus was on an area of around 7.7 square kilometers near Hamburg, in which there are a total of 33 small bodies of water in which crested newts occur. For the study, the researchers carried out genetic examinations and got to know many animals personally: Combed newts are characterized by a conspicuous yellow-orange spotted belly drawing that is unique for each individual and can therefore be used like a fingerprint to differentiate. Over the course of three years, the researchers collected data from 5564 individuals through repeated trapping and releasing in the various ponds. They also recorded the ecological characteristics of the respective sites.
In this way, the team was able to show that the newts, previously considered to be rather local, change their breeding waters significantly more frequently than previously assumed. “We were very surprised how many individuals could be caught in different bodies of water in the three years of our study and that the animals, which supposedly can only cover very short distances, did not necessarily go to the closest body of water,” reports first author Bianca Unglau. Some animals traveled up to a kilometer to do this.
Picky for reproductive success
The migration patterns showed that the animals are evidently looking for bodies of water with a higher quality – they migrate from ponds with rather poorer characteristics. It is noteworthy that in the waters with the high quality, at least the adult animals did not have a better chance of survival, but there were better reproductive successes there, according to the data. “The results of the investigation suggest that crested newts and probably many other amphibians prefer to immigrate to waters that offer them better environmental conditions and thus greater reproductive success,” says Steinfartz. The water quality is therefore of crucial importance for the movements of animals and thus for the demographic and genetic structure of populations, say the researchers.
“However, the study also gives clear indications of how the crested newt can be better protected,” says co-author Benedikt Schmidt from the University of Zurich. “Existing crested newt waters can be made more attractive through simple maintenance measures, for example by minimizing fish stocks and optimizing bank shading.” In this way, the reproductive success and thus the survivability of the entire population can be increased, according to the researcher.
Source: University of Leipzig, specialist article: Molecular Ecology, doi: 10.1111 / mec.16114