Acknowledgements
The author would like to express his appreciation to Bisrat Haile,
Weldegebriel Hadera and Yirga Halefom for their assistance during the
field work, driving through rugged difficult terrains. The running
expenses of this study was funded by Mekelle University and Tigray
Biological and Biodiversity Association (in kind contribution) through
projects: VPRCS/RB/25/2012, VPRCS/RB/20/2012 and
CRPO/CNCS/PhD/MU-NMBU/001/2011.