Thursday, 7 September 2017

Lemurs; ghosts of Madagascar

If asked where the greatest number of families of primates could be found, I suspect that most people (including me until 12 months ago) might suggest Africa or Asia because of apes as well as monkeys and bushbabies, pottos, lorises etc, or maybe even take a punt on the richness of South America. Well, both Asia and South America do support whole five families - but so does Madagascar, in its case all lemurs. With an area of 1.3% and 3.3% respectively of those continents, this island off the south-east coast of Africa is home to a third of all living primate families.

The original lemures were Roman, spirits of the unhappy or even malevolent dead. Just how and why the derived singular came to be attached to Madagascan lemurs (which don't seem at all unhappy in general, and certainly never malevolent) is unclear, though originally it was applied to the Slender Loris, which doesn't help our understanding at all...
Well, if we hear 'lemur', this is what most people visualise, so who am I to disappoint?!
Ring-tailed Lemurs Lemus catta, Anja Community Reserve, southern Madagasca.
It is important to understand that Madagascar is not part of Africa; it parted company from it when Africa-South America left the rest of Gondwana some 160 million years ago, leaving Madagascar on the coast of a mass that included India, Australia and Antarctica. 100 million ago years it and India sailed off on their own, and 88 million years ago India dropped Madagascar off in the Indian Ocean, where it has remained in isolation ever since. Of sizeable land masses, only New Zealand comes even close to this period of evolution unaffected by what was happening elsewhere in the world. Thus the apparently logical presumption that lemurs are part of the African primate group that were separated from their cousins when Gondwana broke up, is entirely wrong. The oldest primates appeared long after Madagascar parted from Africa, or even India.

So, how did they get there? It seems that their ancestors, parents of the primitive Strepsirrhine primate group, which is represented in Africa by bushbabies and pottos and in Asia by lorises, separated from the pottos in Africa somewhere around 60 million years ago. Shortly after that (or at least somewhere between 50 and 60 million years ago) one small intrepid group - theoretically even just one pregnant female - unwillingly made the crossing of the Mozambique Channel on a vegetation raft, assisted by ocean currents which ceased to flow that way between 15 and 20 million years ago. 

But it wasn't so long ago - well within the fairly brief human history of Madagascar - that the island was the undisputed world title-holder for primate diversity. Three entire families, and at least 17 known species, have disappeared since people arrived and began clearing the vast central tablelands for agriculture. Among them were huge lemurs the size of modern gorillas.
Archaeoindris fontoynontii the largest of the family of extinct sloth lemurs, weighing up to 160kg,
making it the largest lemur ever, and one of the largest primates ever to live.
Illustration courtesy Wikipedia.
Additionally, there was a family of koala lemurs, strange tailless apparently exclusively arboreal big lemurs with eyes on the side of their heads, and the so-called monkey lemurs, which seem to have been primarily ground-dwellers.

And now? Well despite the horrific scale and rate of forest destruction in Madagascar, we know of over 100 living lemur species, many of them restricted to one small geographical area, even just one park - and few species can find a living outside of the parks. The key figure however is that less than 10 years ago only around 50 species were recognised; new tools are discriminating similar-looking species every year. At one level of course that is good news, but the other side of the coin is that there are ever more species to conserve, and each time an apparent species is sub-divided, the resultant species have even fewer individuals, and the range in which each lives shrinks. Grimly, for most of these species, the IUCN considers their future bleak in the near future.

But, for now let's just celebrate what there is, with an introduction to each of the five living lemur families. 

Family Daubentoniidae contains just one species, the remarkable Aye-aye Daubentonia madagascariensis. This, the world's largest nocturnal primate, has teeth that grow forever, like those of a wombat or rodent, and thus need constant gnawing to keep them short, and it employs a hunting technique shared by only one other (entirely unrelated) mammal species.
Female Aye-aye, part of population on an island in the Pangalenes Lakes system on the east coast which
has been partially habituated to come to coconuts left for them. It is remarkable to watch their teeth
rip through the shell of the coconut.
Quite properly, flash photography is forbidden, and the animal was constantly on the move, so these photos aren't as clear as I'd like. (My current camera, bought in emergency in a country town when my previous one expired - admittedly a year after a solid dousing in the Amazon basin - is not as good in this situation as its predecessor, a situation I feel forced to rectify, having seen these pics!).
If you enlarge this photo by clicking on it, you can see the very long fingers and skeletally thin
middle one on her right hand.
As well as seeds and fruit, wood-boring insect larvae are a major food source. The Aye-aye taps rapidly on branches, listening for a different sound which tells of a hollow. At that she gnaws into the wood and uses her thin middle finger to extract the snack. Remarkably the Striped Possum of north Queensland and New Guinea uses the exact same technique.
This late night encounter was a highlight of my natural history life.

Family Indriidae has around 20 species of mostly larger lemurs, including one for which the family was named, the Indri Indri indri (just to emphasise the point!), which is the biggest living lemur; a male can be more than 70cm long (they are unique among living lemurs in having no tail) and weigh nearly 10kg.
Indri female and baby, Antasibe-Mantadia NP. This baby will continue to live with its parents and older
siblings until it is time to go and start its own family.
Groups communicate by 'singing', a thrilling wail mostly produced as a duet by the adult pair, that carries far across the forest.
The Indri diet consists mostly of leaves, along with other plant parts.
Tragically the Indri, along with many other lemur species, is classified as Critically Endangered.

Sifakas and Woolly Lemurs comprise the rest of this family.
Diademed Sifaka Propithecus diadema, Vakona, near Antasibe-Mantadia NP.
This lemur is almost as big as the Indri, and beautifully coloured.
This individual is a 'rescue lemur' kept on an island, from which individuals are released back to the wild.
Unfortunately the capriciousness of Air Madagascar meant that we were unable to see wild sifakas,
when they cancelled our flight (at very short notice) to the famed Berenty Reserve in the far south.
This sifaka lives in the eastern rainforests, but other species live across the island in every habitat. Six of the nine species of woolly lemurs (or avahi) have been described in the past decade.

Family Lemuridae contains 27 species of 'true' lemurs' - not a helpful name, as there is nothing false about the others! However they include the genus Lemur, which might explain it. This genus contains just one species, the most famous of all, the dry forest Ring-tailed Lemur, well-represented in zoos around the world, but listed as Endangered in the wild. This is the most terrestrial of living lemurs, and lives in groups of dozens, dominated by females.
Ring-tailed Lemur, Isalo NP.

Eating the fruit of White Cedar - though I'm not sure if this is Melia azederach, which is not native to Madagascar,
and whose fruit are toxic. They eat a wide range of plant food and small animals.
There is a genus of 'typical'(!) lemurs, including the Crowned Lemur, two species of ruffed lemur and seven of brown lemurs, plus six bamboo lemurs. Like the Ring-tailed Lemur they have long bushy tails, woolly fur and are very agile.

Crowned Lemurs Eulemur coronatus, Ankarana NP, are restricted to the dry vine forests of the north.

Sandford's Brown Lemur Eulemur sanfordi, Amber Mountain NP;
female above, male (with white whiskers) below.
Sandford's Brown Lemur was only recognised as a separate species in 2001; it is restricted to
forests of the very far north.
Common Brown Lemur Eulemur fulvus, Antasibe-Mantadia NP.
This one is found in a range of forest types across the northern half of Madagascar.
Red-fronted Brown Lemur Eulemur rufifrons, Isalo NP, gathering fallen figs.
Eastern Grey Bamboo Lemur Hapalemur griseus, Pangalanes Lakes. Like other bamboo lemurs
this is a smaller species, which lives in and on bamboo - except when, as here, it scrounges banana
from a lodge restaurant.
Golden Bamboo Lemur Hapalemur aureus, Ranamofana NP, which was declared in 1991 to
protect this species, five years after it was discovered there.
In bamboo shoots they eat quantities of cyanide which would be lethal to most mammals of their size.
My thanks to Murray Delahoy, who was with me at the time, for offering me this photo, far superior
to what I was able to manage; I could not get a clear window to the lovely animal!
Family Lepilemuridae comprises just one genus, Lepilemur, of at least 26 species of sportive or weasel lemurs  - for obvious reasons the genus name lepilemur is often preferred as a common name! This is a group of medium-sized solitary and nocturnal, long-tailed, powerfully leaping leaf-eating lemurs, found right across the island. Their taxonomy has changed dramatically in recent years, with the number of recognised species trebling. Many are physically indistinguishable but their ranges do not overlap. Despite being nocturnal they are often seen by day, roosting in tree forks or peering from hollows.
Ankarana Sportive Lemur L. ankaranensis, Ankarana NP. This species lives in northern dry vine forests,
especially in Ankarana and Amber Mountain National Parks.

Black-shouldered Sportive Lemur, a hitherto undescribed species, Ifaty Spiny Forest.
This remarkable habitat, in the extremely arid south-west, comprises many spiny tree species, plus baobabs;
it will feature in a posting in the not too distant future. There are no official reserves in this zone.
Family Cheirogaleidae has at least 33 species (the number grows by the year) of the nocturnal little dwarf and mouse lemurs. For the record dwarf lemurs are larger than mouse lemurs; there are even giant dwarf lemurs! The most abundant of these are the highly active mouse lemurs, of at least 21 species all weighing less than 75 grams; in fact, at only around 30 grams Madame Berthe’s Mouse Lemur is the world’s smallest primate. Dwarf lemurs are somewhat slower as well as being larger. I am unable to offer you any photos of my own of these, regrettably; instead I am grateful to my friend Stewart McPherson, whose knowledge of Madagascar and its sometimes unexpected ways smoothed an otherwise rather challenging adventure.
Golden-brown Mouse Lemur Microcebus ravelobensis, Ankarafantsika NP;
photo courtesy Stewart McPherson. This species, described in 1998, is restricted to the
dry forests of this one north-western national park.

Grey Mouse Lemur Microcebus murinus, Ankarafantsika NP;
photo courtesy Stewart McPherson. This species is more widely distributed in a range of western
Madagascar forest types, and is one of the few lemurs not regarded as at risk.
I hope you get to Madagascar one day; it is not always an easy place to visit, but with a good local company (we were unlucky in that, but that is not the norm) it will be well worth your while. (And there is always excellent local rum to smooth your way...) Meantime I'd like to think that the wonderful lemurs will always be there, but unfortunately I can't be that sanguine about at least some of them.

(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.)


Flabmeister said...

What can one say, other than another excellent post!


KayePea said...

An excellent, educational and enjoyable read thanks Ian. :)

Ian Fraser said...

Thank you both, you are very kind! I am so glad you enjoyed it - makes it all worth while!