Tag Archives: Callithrix aurita

Marmosets at REGUA

Marmosets and tamarins (Callithrichidae) are amongst the smallest anthropoids in the new world, they are quite different from monkeys of the old world.    Marmosets are often known as “Squirrel” monkeys for their physical shape and tails resemble squirrels and have noticeably two differences from other monkeys.

Firstly they do not have prehensile tails (which are used to cling with) and secondly, although they are arboreal, they have modified claws rather than nails on all digits except their big toes.   They are omnivorous and have developed specialised lower incisors, which are enlarged and chisel-shaped for gouging tree trunks and branches and vines of certain plant species to stimulate the flow of gum, which they eat, and in some species this forms a notable component of the diet.

The female produces two young a year and they also live in extended family groups of between four and 15 individuals.

The origin of the family Callithrichidae is poorly understood for there are many species (11 marmosets and 16 tamarinds to date with more being discovered principally in the Amazon basin). The Atlantic Rainforest branch sub-divided 13 million years ago coinciding with the actual separation of the Amazonian and Atlantic Rainforest biomes to form Atlantic Rainforest marmosets and tamarins but only recently after genetic studies of the “Callithrix jacchus group” were conducted were they truly separated.   Today six distinct Atlantic Rainforest marmoset species are known and until recently these have been geographically separated.

Common Marmoset
Common Marmoset Callithrix jacchus (© Lee Dingain)

However deforestation of the Atlantic Rainforest to a staggering 7% of its original area has caused migration of two species (C.jacchus, C.penicillata) into C.aurita country whilst the remaining species (C.flaviceps and C.kuhlii) have been reduced to very low numbers. The principle result of the marmoset migration is inter-species hybridisation which is worrying from a conservation point of view as the original species starts to become extinct and a valuable gene type is lost forever.

This is the case for the Buffy-tufted-ear marmoset, C. aurita known from montane Rio de Janeiro state to Sao Paulo and southern Minas Gerais. REGUA is located next to the Três Picos State Park a forested area of some 80,000 hectare of montane sub-tropical forest, home to Callithrix aurita.

Três Picos is located next to the 20,000 hectare Serra dos Órgãos National Park another montane area studied by various University research groups.

These impressive forested mountains are where Rodrigo Carvalho was captivated by this appealing marmoset and initiated his studies on the threatened C.aurita species.   Since then two researchers have helped him in the area of Serra dos Órgãos.   His genetic sampling of specimens in this park as well as local captive breeding populations has led to the conclusion that the species, as we know it, is facing the risk of extinction due principally to the increasing hybridisation with its foreign congeners, C.penicilata and C.jacchus.

What is to be done now? Like every species in distress a master plan is needed, one that locates existing populations; considers species protection in remnant areas; provides a detailed genetic inventory of the captive populations both here and abroad; creates a stud book and the encouragement of further breeding and finally stimulates future reintroductions in safe places that can pull the species back from its plight.

Do we want it to plummet such as the other closely rated species C.flaviceps and C.kuhlii which are bordering extinction today?

There is however another polemic factor. There isn’t a consensual opinion by biologists that species hybridisation is actually negative and some biologists affirm that the current situation is the natural evolution of the species. However others say that we cannot loose an element of our extraordinary diversity that holds a specific function in the complex Atlantic Rainforest due to human irresponsibility, after all the principle is the same; can we loose the panda or the polar bear? Rodrigo and his team believe that this is a very serious issue and they are committed to do something about it.

Fortunately Sao Paulo state and southern Minas Gerais still hold populations of C.aurita, though the forest loss is estimated at more than 95%.   In the interior of Rio de Janeiro`s state, C.aurita can still be found in small forested fragments, however it is clear to all that a consistent plan that directs overall actions is needed.

Fifteen years ago when the Golden Lion Tamarin project was facing the dilemma of the conflict between reintroduced Golden Lion Tamarins and the invasive C.jacchus. Brazil`s Federal Government could not offer clear orders on its sterilisation because no studies had been concluded regarding conflict.    The fact remains that the Golden Lion Tamarin project has been a success.

Rodrigo is a most experienced biologist to lead this initiative and REGUA is most sympathetic to his ideas, but how do we start?

Rodrigo is finalising his own doctorate studies and believes that it is possible to make an inventory of remaining populations of C.aurita as well as its hybrids in the higher altitude forests of REGUA and the National Parks nearby.

Rodrigo wishes to use REGUA as an example of important captive breeding programme eliminating threats, capturing and sterilising non-C.aurita, in a concerted effort to protect them in the higher elevations.    He sees the higher areas as an ideal starting point to reintroduce these marmosets from captive breeding programmes.

Nicholas Locke