First data on nesting ecology and behaviour in the imperial cave salamander Hydromantes imperialis

During the dry season, the European Plethodontid salamanders (genus Hydromantes) usually occupy underground environments (i.e. caves), where they can find cold temperatures and high moisture. Hydromantes breed in hypogean environments, where they usually lay eggs in hidden shelters. Mothers perform a long-lasting parental care of the eggs, which also continues after hatching. Due to the cryptic habitat and behaviour, their breeding biology is poorly known. Most of the available data refer to observations in captivity, while data from wild populations are scarce and deal with the findings of single nests. Here we report the first study on the Imperial cave salamander H. imperialis nesting ecology and behaviour, by performing quantitative observations on multiple nests. We found four nests in a cave located in Central Sardinia. We monitored them through five months, recording environmental features. Nests were associated with cold, humid and dark sectors of the cave, but sectors with nests did not show greater climatic stability than the superficial ones. Nests were continuously attended by females; temporary desertion became more frequent when temperatures were high and it was later in the season. Newborns were attended by their mothers for up to 52 days after hatching. The comparison of breeding biology across multiple Hydromantes species suggests earlier hatch in population/species living in warmer areas, with similar post-hatch brood attendance among species.