Vol. 15 - Deutsches Primatenzentrum

Page 68 Lemur News Vol. 15, 2010
human-induced fire nearby Andasivodihazo,one of the forest
fragments at Tsinjoarivo (Fig. 1). At the time, "May" was believed
to be, as were all eastern rainforest dwarf lemurs, C.
major. Unfortunately, this female could not fully recover and
died soon after the salvage, but her skeletal remains were
carefully preserved and stored at the University of Antananarivo
by Irwin’s team. Seven years later this specimen came
to play a key role in our morphological analysis of dwarf
lemurs at Tsinjoarivo.
Fig.1: Map showing Tsinjoarivo and other localities associated
with Sibree’s dwarf lemurs; see text for details.
In 2006, with the logistic help of Mitchell Irwin and Jean-Luc
Raharison, I began a survey of nocturnal lemurs at Tsinjoarivo.
My assistants and I successfully trapped dwarf lemurs
at two study sites: in one of the forest fragments (Andasivodihazo,
19º41’15"S, 47º46’25"E, 1660 m) and within continuous
forest (Vatateza, 19º43’15"S, 47º51’25"E, 1396 m)
(Blanco et al., 2009). Even to an inexperienced eye, fragment
dwarf lemurs looked different from continuous forest individuals,
in that they were overall smaller, with grayer fur,
marked eye rings and significantly larger female genitalia (Fig.
2). Our morphological and dental analyses determined that
of all the species described by Groves,C.sibreei was the most
similar to forest fragment dwarf lemurs (Blanco et al., 2009).
(Hopefully, sampling of C.sibreei’s holotype will be allowed in
the near future to definitely determine whether or not there
is a genetic match between this specimen and fragment
dwarf lemurs from Tsinjoarivo.) Recent genetic analyses
have confirmed not only that dwarf lemurs from Andasivodihazo
constitute a different clade (and therefore an independent
phylogenetic lineage), but also that the fragment
dwarf lemur species had branched off first and was ancestral
to the other dwarf lemur species (Groeneveld et al., 2010).
To date, no other living population of C. sibreei has been
reported in the wild and more intensive surveys around the
Tsinjoarivo area (including possibly remaining forests nearby
Ankeramadinika, ~100 km from Tsinjoarivo) are warranted
to assess geographic boundaries and population density.
Fig.2: Sibree’s dwarf lemur captured at Andasivodihazo, one
of the forest fragments at Tsinjoarivo.
Conservation concerns
The genetic confirmation of three clades corresponding to C.
medius, C. major and C. crossleyi, each of which has broad
geographic distributions, implied that dwarf lemurs might be
less threatened than previously thought (Groeneveld et al.,
2009). However, the situation for C. sibreei is radically different.
Tsinjoarivo’s unique geographic setting, continuous
with the central plateau on the west and the steep escarpment
of rainforest in the east, may harbor a unique array of
animal communities. To date, C. sibreei has been captured in
sympatry with C. crossleyi at one forest fragment, Andasivodihazo,and
at one intermediate location,Ankadivory.Both of
these areas are subjected to illicit logging and heavy deforestation
(Fig.3).Furthermore,these forest sites are located towards
Tsinjoarivo’s western boundary which reaches some
of the highest altitudes (up to ~1650 m) known in eastern
Fig. 3: Example of logging near Ankadivory, one of the forest
sites where Sibree’s dwarf lemurs were captured.