205.

Sierra Madre Forest Mouse

Apomys sierrae

French: Apomys de la Sierra Madre / German: Sierra-Madre-Philippinenwaldmaus / Spanish: Raton de bosque de Sierra Madre

Other common names: North Sierra Madre Forest Mouse, Sierra Apomys

Taxonomy. Apomys sierrae Heaney et al., 2011, “Philippines: Luzon [Island]: Cagayan Province: 3-5 km SW Mt. Cetaceo peak, 1400 m elevation, 17-69561°N, 122-01683°E.”

Apomys sierrae 1s a member of subgenus Megapomys. It seems not to have any particularly close affinities, but nearest phylogenetic relatives may be A. magnus, A. aurorae, A. zambalensis, and A. iridensis . A. sierrae was tentatively reported as A. datae by F. Danielsen and colleagues in 1994; it has been newly collected over much of its geographic range only since the mid-2000s. Currently regarded as monotypic but in need of further assessment.

Distribution. Luzon I (Sierra Madre, Mt Lataan, Mungiao Mts, and Mt Palali) and adjacent Palaui I, Philippines.

Descriptive notes. Head—body 122-171 mm,tail 118-154 mm, ear 18-21 mm, hindfoot 31-40 mm; weight 64-111 g. Apomys species are soft-furred, small to medium-sized murines with relatively unspecialized body form; distinguished from other Philippine murines by a distinctive suite of features, including long, narrow hindfeet, thinly furred tail, unreduced eyes, relatively large and thinly furred ears, vibrissae on snout very elongate and, folded back, reach to shoulder or beyond, reduction to two mammae on each side, both inguinal, and a simplified molar pattern with cusps united into transverse laminae. Members of subgenus Megapomys are larger, shorter-tailed species active primarily on ground; in most forest habitats across Luzon they are the most abundant terrestrial mammal in any given community. The Sierra Madre Forest Mouse is a medium-sized Megapomys with fur on upperparts variable, dark brown with rusty tints dorsally in Sierra Madre populations and medium brown with yellowish tints in Caraballo Mountains populations; in both populations, fur on underparts and inside of limbsis white or nearly white with orange wash, hairs medium to pale gray at bases; border between upperside and undersideis slightly diffuse; head has whitish-gray furon throat but cheek and sides of snout brown. Dark fur on foreand hindlimbs terminates at wrist and ankle, upper surfaces of foreand hindfeet mostly white with scattered dark hairs; hindfeet relatively long and narrow, undersurface heavily pigmented for most of length though not on plantar pads, hallucal pad long and narrow, other plantar pads relatively small, digits relatively long and narrow, and bearing sharp, curved claws. Tail is relatively long (95-100% of head-body length) and sharply bicolored, dark brown above and white below for all or most of length, sometimes with short white tip. Cranium is similar to those of other Megapomys but rostrum relatively slender, braincase globular, and molars relatively narrow.

Habitat. Evergreen tropical rainforest, including lowland and montane rainforest types, and narrowly extending into “mossy forest.” At lower elevations, it occurs in lightly to heavily disturbed forest, as well as inprimary forest. Elevational range on Luzon 475-1700 m; recorded at 153 m on Palaui I.

Food and Feeding. L.. R. Heaney and others stated in 2016 that Sierra Madre Forest Mice “showed a strong preference for earthworm bait rather than fried coconut on Mount Cetaceo, but a roughly equal preference on Mount Palali; they appear to be omnivorous overall.”

Breeding. Seven pregnant females had average of 1-7 embryos (range 1-2).

Activity patterns. According to Heaney and others, nearly all captures of Sierra Madre Forest Mouse were made at night, and nearly all on ground surface.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List but its wide distribution and elevational range, local abundance, and occurrence in regrowth habitat following heavy disturbance all attest to its resilience. Sierra Madre Forest Mice were the most commonly captured small ground mammal between 780 m and 1707 m on Mount

Palali inthe Caraballo Mountains, and they were similarly common at 1300-1500 m on Mount Cetaceo in Cagayan Province.

Bibliography. Alviola et al. (2011), Danielsen et al. (1994), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Alviola et al. (2011).