The northern voalavo is found at 1,250 to 1,950 m (4,100 to 6,400 ft) above sea level in montane wet and dry forests in the Marojejy and Anjanaharibe-Sud massifs.

The northern voalavo is a small, mouse-like rodent with soft, grey fur that is only slightly darker above than below.

[6] Meanwhile, in 1999, Sharon Jansa and colleagues published a molecular phylogenetic study of the Nesomyinae, the native Malagasy rodents, using the mitochondrial gene cytochrome b.

However, the DNA of Petter's tufted-tailed rat, a possible close relative of northern voalavo, could not be sampled, so Jansa and colleagues recommended further evaluation of the problem.

[3] The fur is soft, short, and thick,[15] and appears dark grey on most of the upperparts, but more brownish on the sides.

The tail is longer than the head and body and appears naked for most of its length, but fine hairs are visible near the tip.

The rostrum, the front part of the skull, is narrow and fairly long;[16] it is shorter in eastern voalavo.

The zygomatic arches (cheekbones) are narrow, but as usual in nesomyines contain a relatively long jugal bone.

[17] The incisive foramina (openings in the front part of the palate) are medium in length, and do not reach the first molars.

[14] The bony palate is broad and lacks notable ridges and other features, except for a pair of foramina (openings) near the place where the first and second molars (M1 and M2) meet.

[17] A thin alisphenoid strut (a piece of bone on the lower side of the skull separating two foramina) is present in specimens from Marojejy, but not in those from Anjanaharibe-Sud.

[19] The upper incisors are orthodont (with their cutting edge perpendicular to the plane formed by the molars) and have yellow to light orange enamel.

[14] As in Eliurus, the molars are incipiently hypsodont (high-crowned) and the individual cusps have lost their identities, having merged into transverse laminae not connected longitudinally.

[2] At Anjanaharibe-Sud, the species has been found in wet mountain forest at 1,950 m (6,400 ft), where it occurred with the indigenous rodents Major's tufted-tailed rat and island mouse as well as the introduced black rat (Rattus rattus), and in drier forest at about 1,300 m (4,300 ft), where it may live alongside other species of Eliurus and Voalavoanala.

[3] The species is nocturnal (active during the night), is solitary, probably eats fruits and seeds, and bears up to three young per litter.