Decades ago, when I was a medical student at Southampton, I joined an expedition that usually at the time granted permission to carry out wildlife research in Madagascar. I’d known the Great Red Island as a world like no other since Attenborough’s Zoo Quest to Madagascar. Following Independence though, the country had courted Russia and for a decade or so visits from Western researchers were discouraged. 
We happened to apply to work there at the beginning of a new more open policy in 1981 though. Intent on contributing the knowledge of lemur ecology, we visited two forested areas 1000 miles apart. The second was snuggled in the shelter of the sheer cliffs of the Ankarana limestone Massif in the north of Madagascar.
We camped in a yawning cave entrance and found ourselves sharing a water supply with lemurs that hadn’t learned to fear humans, although their big round eyes did make them look constantly startled. The males had a striking black triangle of fur between their teddy-bear ears and the females a chestnut tiara; these were crowned lemurs. At the time I assumed that such engaging and unshy mammals would have been studied by primatologists of international standing so I concentrated on documenting the less obviously attractive invertebrates inhabiting the caves. Yet the caves that riddled the massif gave us access to a sunken forest and otherwise inaccessible luxuriant gorges which acted as natural nature reserves for lemurs and other wildlife and it became clear that this was a very special environment within Madagascar’s other-worldly island-continent.
 

a male crowned lemur, Eulemur coronatus

 

a female crowned lemur, who are very much in charge

Only later did I discover that the elegant crowned lemurs who daily visited the pool where we’d camped hadn’t been studied in the wild by zoologists. I resolved to return to research the crowned lemurs, document their behaviour, attempt to assess how threatened they were and how restricted in their geographical distribution and range. Such a study would enable biologists to understand how best to conserve a species that was, in common with many lemur species, likely to be endangered.
It took five years to assemble a suitable scientific team for the return expedition. They needed to be biologists capable of living in the forest for a month or two as well as competent cavers who could organise a rescue if needed. The environment was remote and the landscape hostile and if there was an accident we couldn’t expect help with any evacuation. 
The Ankarana Massif is small but moving around was challenging. I’d at first assumed we might enter sunken forests by crossing the limestones but although it was possible to summit the massif where there was all manner of weird-looking bottle-bottomed drought-resistant plants, the surface was fakir’s nail-bed of points which ripped boots to pieces in weeks. The spiky rock is known locally as tsingy meaning walking on tiptoes, which we never learned to do. 
During this second expedition, we based ourselves in a forested canyon at a spot that is still known as Le Campement des Anglais. When we attempted to estimate the population of crowned lemurs in the part of this part of the forest, the density of lemurs appeared to be the highest recorded for any wild primates globally, and this was without trying to count mouse lemurs, sportive lemurs and others which also shared the area.
As we became familiar with the terrain, it became clear that the unusually high density of lemurs was a seasonal phenomenon. During the dry season the surface of the massif is parched and lacerating and the few plants that cling on up there are leafless while the surrounding savannah also provides little nutrition for hungry herbivores. The gorges and canyons and isolated forests within the massif, which are irrigated by subterranean rivers, remain green though and provide good foraging opportunities for the lemurs. 
When the rains come the lemurs expand their range, skilfully negotiating the ferocious tsingy to browse on the blossoming and fruiting plants growing in the cracks and crevices of the limestones. Even bare rock becomes covered in mosses and bryophytes which in turn feed grazing snails and other invertebrates providing omnivorous lemurs with protein-rich snacks to augment a fig-rich diet.
Until our study, zoologists had assumed that crowned lemurs were only active during daylight hours, but we slept in hammocks and were made aware that this species like to eat in the middle of the night too. Around 2am there would be activity in the canopy above our camp and half-eaten fruit and a certain amount of poo would rain down on us.
As well as completing and publishing the first study of wild crowned lemurs, we compiled a list of the other animals present and this ecological inventory helped emphasise the zoological importance of Ankarana. It had been designated as a Special Reserve in 1956, during the French colonial era, but by the 1980s there was no protection that should have accompanied that status. Partly due to our efforts, WWF funded the employment of rangers to patrol the reserve on mountain bikes for a while, and over time, the area was recognised as being worthy of National Park status. 
When I returned to Ankarana this year, it was a delight to spend time again with lemurs in their home territory as they move around the forest grunting good-naturedly to keep in contact with the rest of the troop. Their opposable thumbs and lolly-pop-tipped fingers and toes cushioned and facilitating branch and tree-trunk grabbing after prodigious leaps while their big amber eyes forever look as if they had just heard some shocking gossip.
I was nervous of what I would find on this visit though as proper protection of key reserves isn’t easy when government needs to balance competing priorities and pressures. Forests that grow valuable tropical hardwoods can provide rich pickings for people motivated by profit over conservation or development of wildlife tourism. Furthermore, disastrous cyclones or drought may force subsistence agriculturalists to look to the forest for resources to help them survive.   
Hearteningly though there have been excellent developments since I was last in Madagascar. There are now forest corridors between Ankarana and other untouched areas where lemurs thrive. On the east side of the massif there is a staffed park headquarters and from there we employed Gautier, an expert wildlife guide who was impressive in his knowledge and ability to spot well-camouflaged animals indeed in our heat-sapped state, he was far more enthusiastic about showing us everything than we were. He also demonstrated how much we had missed during our researches. There were chameleons and mouse lemurs everywhere!
 

A sleepy sportive lemur at Ankarana

 

Mum and youngster: sportive lemurs at Ankarana looking mildly apprehensive

Several lodges have been built close to the park headquarters along the Route National Six including one with its own private “domaine”. Here Nando, local wildlife enthusiast-cum-barista, took us on a tour of their protected patch of tsingy; he pointed out reptiles and birds, and gave scientific names to rare plants.
Now that the Ankarana Massif is attracting foreign ecotourists, conservation is seen as worthwhile. I hope that now money can be made from foreign visitors, this will be a force for conservation and may help resist those who would otherwise extract valuable ebonies and rosewoods from Madagascar’s rich but threatened forests.

I have posted some Madagascar wildlife photos on my Instagram pages @longdropdoc