Apomys sierrae

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Apomys sierrae

Heaney, et al. 2011. Fieldiana Life and Earth Sciences, 2: 34. Type Locality: 3.5 km SW Mt. Cetaceo peak, Cagayan Province, Luzon Island, Philippines, elevation 1400 m (17.69561d N, 122.01683d E)

© The Field Museum. Photograph by L Heaney and A Niedzielski.



Family: Muridae

English common names:  Sierra Madre apomys, Sierra Madre forest mouse



Total length: 262-296 mm; tail: 124-154 mm; hind foot: 34-39 mm; ear: 18-21 mm; weight: 73-110 g. In the Sierra Madre range, Apomys sierrae has dorsal fur that is dark brown with rusty-reddish tints, while on Mt. Palali (Caraballo Mountains), the dorsal fur is medium brown with a yellow tint. Also, the skin of the ears and feet of this latter group is paler than in the individuals from the Sierra Madre. Ventral fur is medium to pale gray at the base and white or white washed with pale ochraceous at the tips. The tail, which is about equal to head and body length, is distinctly bicolored—dark brown dorsally and, usually, white ventrally; only a few individuals have a white tip.  The dorsal surface of the hind foot is white with scattered dark hairs.  

Apomys minganensis has longer, denser and darker dorsal fur and also many dark hairs on the dorsal surface of the hind foot. Apomys sierrae is usually smaller than A. magnus, and the dorsal fur of the former is dark brown with rusty reddish tones or rich rusty orange-brown as opposed to the dark brown with prominent black guard hairs of the latter. Apomys magnus has ventral fur that is paler gray at the base and nearly white at the tip. Apomys sierrae has a reddish tint in its dorsal fur as opposed to the more yellow tint of A. aurorae; otherwise, they are quite similar externally.  Also, A. sierrae tends to have a longer hind foot, although other measurements are similar. Apomys sierrae is smaller than A. zambalensis in almost all measurements, and the dorsal pelage of A. zambalensis is a bright rusty umber, rather than dark brown with rusty-red tints.  Apomys microdon and A. musculus occur sympatrically in some areas; both are much smaller with proportionately longer tails.



Known from Palaui Island (FMNH), the northern Sierra Madre range in Cagayan Province (USNM); Mt. Lataan and Mungiao Mountains, Quirino Province (FMNH); and Mt. Palali, Caraballo Mountains, Nueva Viscaya (FMNH), Luzon Island (Heaney et al., 2011).  

© The Field Museum


Habitat and Ecology:

Currently documented from ca. 475 to 1800 m on Luzon, although it was found at 153 m on Palaui Island, where the maximum elevation is approximately 300 m. On an elevational survey of Mt. Palali, Apomys sierrae was the most frequently captured species of non-volant small mammals in all the collection sites: 780 m, 900 m, 1040 m, 1300 m, 1420 m, and 1707 m. The forest type at these elevations included lowland disturbed agro-forest, regenerated dipterocarp forest, transitional lowland/lower montane forest, mature montane forest, and mossy forest. On an elevational survey of Mt. Cetaceo, A. sierrae was the most abundant non-volant small mammal at all four survey localities: 1300 m, 1400 m, 1500 m and 1550 m. These elevations represent lower montane forest, montane forest, and old-growth mossy forest. Apomys sierrae forages on the ground at night nocturnally, searching for earthworms and seeds.  Apomys microdon and A. musculus both occur sympatrically over parts of its range; both are small, primarily arboreal species.

Apomys sierrae from Mt. Cetaceo. © The Field Museum. Illustration by V Simeonovski.

Apomys sierrae from Mt. Palali. © The Field Museum. Illustration by V Simeonovski.



Widespread and abundant.



Surveys in the area of where the Caraballo Mountains and the Central Cordillera come together, a potential overlap in the distribution of Apomys sierrae, A. abrae, and A. datae, could produce interesting data as to the comparative habitat usage and interactions of these species.