Philippine brown deer (Rusa marianna)

GenusCervus (1)
SizeHead-body length: 100 – 151 cm(2)
Shoulder height: 55 – 70 cm (2)
Weight40 – 60 kg (2)

Classified as Vulnerable (VU) on the IUCN Red List (1).

The Philippine brown deer is a diminutive, compactly-built deer with relatively short antlers that only reach 20 to 40 centimetres in length. In general, this species is entirely brown, with the exception of the underside of the tail, which is white. However, there are regional variations in colour, such as one population found on Mindanao where the deer’s coat has been reported to be a pale, sandy grey (2). Certain populations of the Philippine brown deer also differ significantly in body size (3). Consequently, the Philippine brown deer has been split by some authorities into a number of regionally separated subspecies (4) (5).

The Philippine brown deer occurs throughout most of the Philippines, with the exception of the islands of Negros, Panay, Palawan, Sulu, and the Babuyan and Batanes island groups (3). In addition to its native range, introduced populations of this species are found on the islands of Guam, Saipan and Rota in the Mariana Islands and Pohnpei in the Caroline Islands (2). The Philippine brown deer was also historically introduced to Japanese Bonin Islands, where it later became extinct (6).

The Philippine brown deer occupies a variety of habitats, from wooded lowlands to forested mountain slopes, up to 2,900 metres above sea level (2).

There is currently a lack of detailed information about the life history of the Philippine brown deer. It is known that breeding most commonly occurs from September to January, with females giving birth to a single fawn marked with light coloured spots, which disappear after a few weeks. During the rut, females may form small groups of up to eight individuals, but the males remain solitary and are aggressive (7).

Resting during the day, hidden in dense vegetation, the Philippine brown deer commences activity in the evenings which continues throughout the night until dawn. This species generally favours the edges of forests or forest clearings, browsing upon a variety of vegetation such as grasses, leaves, fallen fruit and berries (7). In the regions where it has been introduced, the Philippine brown deer has caused significant damage to indigenous ecosystems, preventing forest regeneration as well as eating large amounts of crops (6) (8) (9).

The main threat to the Philippine brown deer is hunting for its meat, compounded by the ongoing destruction of its habitat (2) (8). Despite portions of this species’ range being located in protected areas within the Philippines, poor enforcement of regulations allows widespread illegal logging activity, mining, and conversion of land to agriculture (10). As a consequence of these threats, the Philippine brown deer’s population is highly fragmented and declining throughout most of its range (1).

In the areas where it has been introduced, the Philippine brown deer is afforded some protection, as it is illegal to hunt the deer on Saipan, and hunting regulations are in effect on Guam and Rota. Unfortunately, despite this regulation, illegal hunting continues unabated (8). In its native range, there are currently no specific measures in place to conserve the Philippine brown deer. In order to effectively protect this species, National Park regulations must be properly enforced and the protective area network expanded (1). Conservation International-Philippines is currently collaborating with the Field Museum in Chicago, the Haribon Foundation and local partners in the Philippines to identify and delineate Key Biodiversity Areas containing globally threatened or geographically restricted species. These areas will help to inform policy makers about where the most important areas requiring protection are situated (10).

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  1. IUCN Red List (December, 2009)