Most of us go on holiday to find new ways to relax and have fun, or if we're a bit more pretentious we might go to find ourselves. Primatologist Charlie Gardner went on holiday and found a new population of dwarf lemurs, which might even be a new species.
Gardner, who is based at the University of Kent in Canterbury, UK, has spent the last ten years living and working in Madagascar. In April 2015, he went on holiday with his wife Louise Jasper, a nature photographer.
They spent four days camping on a small island called Nosy Hara, which lies 6km off the northern tip of Madagascar.
On the evening of 9 April, they went for a walk in the forest and saw two lone dwarf lemurs within ten minutes of each other. The next night, they found a group of four feeding together.
They described their discovery in the journal Primates.
Gardner and Jasper were taken completely by surprise, because no lemurs were known to live on Nosy Hara. The question now is, what kind of lemur are they and how did they get there?
Madagascar is home to dozens of species of lemurs, a group of primates that are found nowhere else on Earth.
The dwarf lemurs all belong to one genus, Cheirogaleus. Until 2000, there were thought to be only two species: a small, grey one in the western dry forests (Cheirogaleus medius) and a larger, reddish one from the eastern rainforests (C. major).
The animals on Nosy Hara clearly belong to a western lineage
Then scientists started analysing the lemurs' DNA, and it turned out that there were many more species than that, most of which look pretty much alike. A study published in 2014 estimated that there were actually 18 species.
So far we know almost nothing about the new dwarf lemurs. They are active at night and they eat fruit, like all dwarf lemurs, but that is about it. As a result it is hard to place them.
"The animals on Nosy Hara clearly belong to a western lineage, since they are small and grey coloured, but beyond that we cannot say," says Gardner.
They are a fair way from their neighbours, Gardner says. "The nearest population of grey dwarf lemurs is from the Ankarana massif about 65 km south." That population might be a separate species, distinct from all the others on mainland Madagascar.
The Nosy Hara lemurs might have arrived very recently, perhaps after drifting over to the island on a raft of vegetation.
They were incredibly tame, showing no fear of us at all
That would explain why no one has seen them before. It would also mean they aren't a new species, because they will still be genetically similar to the population they came from.
However, Gardner says there is some "rather circumstantial" evidence that the lemurs have been there for a while.
"The animals appeared quite small, and they were incredibly tame, showing no fear of us at all," says Gardner. Species that live on isolated islands often evolve to be a different size. If there are no predators around they also become quite fearless, which can be dangerous if a predator turns up later: that's what did for the dodo.
These points suggest that the lemurs have been isolated on Nosy Hara for a long time. "If this is the case then they would likely represent a new species," says Gardner. However, he says it is "impossible to know without analysing some genetic material."
Whether they are a new species or not, the dwarf lemurs of Nosy Hara are in a precarious situation. "The population is likely to be incredibly small," says Gardner.
A single fire or disease outbreak could affect the whole island
The island has an area of 320 hectares (3.2 sq km), which is smaller than New York's Central Park. What's more, "much of that is covered with bare, craggy limestone rather than forest, and thus wouldn't support dwarf lemurs."
Based on the population densities of other dwarf lemur species, Gardner says he "would 'guesstimate' that the total population may be in the hundreds."
That puts them at immediate risk, because a single harmful event could obliterate them. "A single fire or disease outbreak could affect the whole island, or a drought could prevent trees from fruiting for a single year, and that could be enough to wipe out the whole population," says Gardner.
"If this does turn out to be a new species, it will meet the criteria to be listed as critically endangered," says Gardner. He suggests setting up a small colony in captivity, so that if the wild lemurs do get wiped out, the species – if it is one – would survive.
All lemurs on mainland Madagascar are threatened primarily by deforestation, and to a lesser extent hunting
On the positive size, the Nosy Hara dwarf lemurs are probably in less danger from humans than other lemurs – simply because people don't visit the island very often.
"All lemurs on mainland Madagascar are threatened primarily by deforestation, and to a lesser extent hunting," says Gardner. "These shouldn't be an issue for the dwarf lemurs of Nosy Hara since the island is uninhabited and completely unsuitable for farming, so there is no reason for anyone to clear the forest."
Dwarf lemurs are the only primates that hibernate, and this may be what allows the Nosy Hara population to keep going. "It may be that this capacity to hibernate is what allows the dwarf lemurs to survive on such a small island as Nosy Hara, because they can survive times of scarcity during the dry season," says Gardner.