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Datasheet

Rusa marianna
(Philippine deer)

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Datasheet

Rusa marianna (Philippine deer)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Animal
  • Preferred Scientific Name
  • Rusa marianna
  • Preferred Common Name
  • Philippine deer
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Chordata
  •       Subphylum: Vertebrata
  •         Class: Mammalia
  • Summary of Invasiveness
  • Philippine deer are a medium-sized deer native to the Philippines. The species was first introduced to Micronesia in about 1771, when it was released on Guam. Additional introductions followed on four other Micronesia...

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Pictures

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PictureTitleCaptionCopyright
Rusa marianna (Philippine deer); adult male.  (formerly Cervus mariannus), the endangered Philippine deer, found on the outskirts of Davao, Philippines. March 2012.
TitleAdult male
CaptionRusa marianna (Philippine deer); adult male. (formerly Cervus mariannus), the endangered Philippine deer, found on the outskirts of Davao, Philippines. March 2012.
Copyright©Gregg Yan - CC BY-SA 3.0
Rusa marianna (Philippine deer); adult male.  (formerly Cervus mariannus), the endangered Philippine deer, found on the outskirts of Davao, Philippines. March 2012.
Adult maleRusa marianna (Philippine deer); adult male. (formerly Cervus mariannus), the endangered Philippine deer, found on the outskirts of Davao, Philippines. March 2012.©Gregg Yan - CC BY-SA 3.0

Identity

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Preferred Scientific Name

  • Rusa marianna (Desmarest, 1822)

Preferred Common Name

  • Philippine deer

Other Scientific Names

  • Cervus mariannus Desmarest, 1822
  • Cervus unicolor Kerr, 1792

International Common Names

  • English: Philippine brown deer; Philippine sambar

Local Common Names

  • Guam: binadu
  • Northern Mariana Islands: binadu
  • Philippines: ugsa; usa

Summary of Invasiveness

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Philippine deer are a medium-sized deer native to the Philippines. The species was first introduced to Micronesia in about 1771, when it was released on Guam. Additional introductions followed on four other Micronesian Islands and the Ogasawara Islands through 1966. Only Rota and Saipan (Commonwealth of the Northern Mariana Islands), Guam and Pohnpei (Federated States of Micronesia) currently support populations. Numbers on these islands grew rapidly when adequately protected from hunting. Deer became common enough to cause serious agricultural damage in the Ogasawara Islands (1880s), Guam (1890s to 1940s), and Pohnpei (1940s-1960s), and ecological damage on Pohnpei (1940s), Rota (1970s-1980s), and Guam (1980s to present). Currently, deer abundance is very high (more than 60 animals/km2) in parts of Guam, where deer and feral pigs combine to cause extensive damage to native forests. The species is not on any alert list for pest species. It is listed as Vulnerable by the IUCN in its native range.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Chordata
  •             Subphylum: Vertebrata
  •                 Class: Mammalia
  •                     Order: Artiodactyla
  •                         Suborder: Ruminantia
  •                             Family: Cervidae
  •                                 Genus: Cervus
  •                                     Species: Rusa marianna

Notes on Taxonomy and Nomenclature

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Philippine deer have a complex taxonomic history, with numerous taxa assigned to various populations in the species native range in the Philippines (Grubb and Groves, 1983; Whitehead, 1993; Grubb, 2005). The species was originally described from the extralimital population on Guam, which added further confusion to the identification of Philippine populations. Rusa marianna has been variously treated as a full species or a subspecies of sambar (R. unicolor) within the genus Cervus (subgenus Rusa). Taxonomic assessment by Grubb and Groves (1983) confirmed it as a distinct species. Recent genetic analyses have supported the designation of Rusa as a genus (Pitra et al., 2004). 

Morphometric analysis (Meijaard and Groves 2004) placed the species within the genus Cervus.

Four subspecies are currently recognized, with the nominate form, R. m. marianna, present from Luzon south to Leyte, and in Micronesia; R. m. barandana on Mindoro; R. m. nigella at higher elevation sites on Mindanao; and R. m. nigricans in lowland areas of Mindanao and on Basilan (Grubb and Groves, 1983; Oliver et al., 2008). Taxonomic relationships within the species are yet not fully understood, especially for R. m. nigella and R. m. nigricans, which display variation in body size, pelage colour, and other characters (Heaney et al., 1998; Oliver et al., 2008). The taxonomic status of a light coloured form on Leyte has not yet been assessed (C.R. Cox, in Oliver et al., 2008). 

Philippine deer are most closely related to the Visayan spotted deer (R. alfredi), which is now restricted to Panay and Negros in the west-central Philippines and does not overlap geographically with R. marianna (Meijaard and Groves, 2004).

Description

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Philippine deer are medium-sized deer demonstrating some geographic variation in size (Heaney et al., 1998). The two Mindanao subspecies, R. m. nigricans and R. m. nigellus, are the largest and smallest subspecies, respectively (Grubb and Groves, 1983; Oliver et al., 2008), although average size differences remain poorly quantified for all subspecies. For the species as a whole, measurements include a weight of 40-96 kg, a head and body length of 100-170 cm, a shoulder height of 55-95 cm, a tail length of 8-14.5 cm, and an ear length of 9-12 cm (Nowak, 1999; Wiles et al., 1999). Fawns at 4-8 days of age weigh about 3.0 kg and have a shoulder height of about 32 cm (Wheeler, 1979). Like most deer, R. m. marianna exhibits pronounced sexual dimorphism, with males weighing on average about 50% more than females and being about 12-13% larger in body length and shoulder height (Wiles et al., 1999).

Most populations feature nearly uniform medium to dark brown pelage with coarse hair, although the undersides and legs may be somewhat paler. A rump patch does not exist, and the underside of the tail and insides of the ears are whitish or light brown. Some populations may be darker or paler overall (Grubb and Groves, 1983; Nowak, 1999; C.R. Cox, in Oliver et al., 2008). Head features include deep suborbital pits and relatively small ears.

Antlers of mature bucks are typically slender and three-tined, featuring a rear-facing terminal fork and a single brow tine. An extra point or two is occasionally present (Wiles et al., 1999). Antlers generally measure 16-40 cm long, but can reach a maximum length of 53 cm (Wheeler, 1979; Grubb and Groves, 1983; Nowak, 1999). Spike bucks generally have antlers measuring less than 15 cm. Unusually massive and non-typical antlers are regularly noted on Rota and occasionally on Pohnpei (Wiles et al., 1999). Antlers of this enlarged type are variable in shape with up to 5-10 points per side, sometimes show a tendency to become palmate near the terminal fork, and have basal diameters 1.2-1.7 times larger than normal antlers.

Distribution

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Philippine deer are native to the Philippine Islands, where they are distributed across much of the country. The species has been recorded on the following islands (and provinces): Luzon (Abra, Bataan, Batangas, Cagayan, Ilocos Sur, Isabela, Kalinga, Nueva Ecija, Rizal, Sorsogan, and Tarlac provinces), Mindanao (Augusan del Norte, Bukidnon, Davao del Norte, Davao del Sur, Davao Oriental, Lanao del Norte, Lanao del Sur, Misamis Occidental, North Cotabato, Sarangani, South Cotabato, Sultan Kudarat, Zamboanga del Norte, and Zamboanga del Sur provinces), Basilan, Leyte, Mindoro, Polillo, and Samar (Oliver et al., 2008; Heaney et al., 2010). It is extinct on Biliran and Catanduanes, possibly extinct on Bohol and Marinduque, and apparently absent from Dinagat and Siarga. Current distribution is highly fragmented on most islands and is much reduced from the historical distribution (Oliver et al., 2008). The species does not occur on the main west-central islands of Bohol, Cebu, Negros, Palawan, and Panay.

Philippine deer have been successfully introduced to the US territory of of Guam (540 km2), Rota (85 km2) and Saipan (123 km2) in the Commonwealth of the Northern Mariana Islands, and Pohnpei (355 km2) in the Federated States of Micronesia (Wiles et al., 1999). Failed introductions have occurred on Tinian (102 km2) in the Northern Mariana Islands and in the Ogasawara Islands (104 km2) of Japan (Wiles et al., 1999; Miura and Yoshihara, 2002). Guam was the site of the first Micronesian introduction, using animals from the Philippines. Subsequent introductions in Micronesia used deer from within the region.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

JapanAbsent, formerly present1966Introduced1700-1800sWiles et al., 1999; Miura and Yoshihara, 2002Subspecies of first introduction unknown, second was R. m. marianna; introduced to the Ogasawara Islands of Chichi-jima, Haha-jima, and Ototo-jima
PhilippinesLocalisedNative Not invasive Grubb and Groves, 1983; Rickart et al., 1993; Heaney et al., 1998; Oliver et al., 2008; Heaney et al., 2010Present on Basilan, Leyte, Luzon (Bataan, Cagayan, Ilocos Sur, Isabela, Kalinga, Nueva Ecija, Rizal, Sorsogon, and Tarlac provinces), Mindanao (Agusan del Norte, Bukidnon, Davao del Sur, Davao Oriental, Lanao del Norte, Lanao del Sur, Misamis Occidental, Sarangani, South Cotabato, Sultan Kudarat, Zamboanga del Norte, and Zamboanga del Sur provinces), and Mindoro. Extinct on Biliran and Catanduanes

Oceania

GuamWidespreadIntroduced1771 Invasive Wiles et al., 1999R. m. marianna; distributed islandwide; population size unknown but large
Micronesia, Federated states ofLocalisedIntroduced1904/5 Invasive Wiles et al., 1999R. m. marianna; present only on Pohnpei,where it is widespread; population size unknown but fairly common in parts of the island
Northern Mariana IslandsLocalisedIntroduced1880 Invasive Wiles et al., 1999R. m. marianna; present only on Rota and Saipan; widespread on Rota where population size unknown but fairly common on much of the island; localized on Saipan, where population size unknown, but small; extirpated on Tinian

History of Introduction and Spread

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Wiles et al. (1999) summarized all Micronesian introductions of Philippine deer based on a review of historical literature. These records were incomplete in many details, especially regarding whether initial introductions were supplemented with additional animals. Most of the introductions were conducted by colonial governments, and in all cases, deer were presumably transplanted to act as a food source for islanders and colonial officials, and possibly as a resource for hunting. Philippine deer were successfully introduced to Guam by the island’s Spanish colonial governor, probably in 1771. The source of these animals in the Philippines is undocumented, but was likely Luzon. The original number of animals brought to Guam is also unknown, but was probably small because of the limited cargo capacity of ships at the time. Deer have generally been considered common to abundant on the island for much of the time since the late 1700s, although several periods of decline have occurred. Agricultural and ecological damage was first noted in the 1890s and early 1980s, respectively, but likely went unreported prior to these dates. A recent attempt to introduce deer as game animal to Tinian occurred in 2010 with a small number of deer moved from Rota (A. Brooke, Navy Natural Resources, Guam, personal communication, 2012).

The first introduction to the Commonwealth of the Northern Mariana Islands occurred on Rota in about 1880 and was conducted by the Spanish governor of Guam. No other information about this event is available, except that deer were confined for a number of years to a fenced-off forested peninsula on southwestern Rota, where they became common. They eventually were released to other parts of the island no later than the early 1930s. Ecological damage from deer was noted on Rota in the 1970s and 1980s, and may be continuing. They also cause minor agricultural damage. German colonial authorities transported six deer from Rota to Saipan in 1900. Deer increased swiftly and spread to multiple locations on the island within a decade. Six animals were taken from Saipan and Rota to Tinian in the early 1960s, presumably by American Trust Territory officials or local residents. Numbers on Tinian initially increased, but the population then declined and died out by the late 1970s or early 1980s.

An attempt to establish Philippine deer in the Federated States of Micronesia was made in 1880, when a few animals were taken to Pohnpei from Guam. Foreign citizens living on the island may have conducted this introduction, which occurred six years before formal colonial occupation of the Caroline Islands began. This introduction apparently failed within a decade. Another was attempted in 1904 or 1905, when the German colonial government brought three deer from Saipan. It was apparently successful, although little information is available on the population’s status until 1940, when deer were noted as present in the mountainous interior of the island. Deer were both an agricultural and ecological pest by the late 1940s.

Philippine deer were also introduced to Japan’s Ogasawara Islands sometime before 1853 (Wiles et al., 1999; Miura and Yoshihara, 2002). No information exists on who conducted the introduction, the number of animals involved, or their source, although the Philippines and Guam were the only two locations from which they could have originated. This introduction was successful, with deer becoming numerous enough to become an agricultural pest by the 1880s. Control efforts to limit crop damage reduced the population, which was eventually extirpated by the 1920s. In 1966, during U.S. administration of the islands, the U.S. Navy transported two deer from Guam to Chichi-jima, but the population never grew beyond a few animals and disappeared by 1980. 

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Guam Philippines 1771 Animal production (pathway cause) Yes Wiles et al. (1999) Deliberate introduction as game animal
Guam Micronesia, Federated states of 1880 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No Wiles et al. (1999) Deliberate introduction as game animal
Guam Japan 1966 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No Miura and Yoshihara (2002); Wiles et al. (1999) Deliberate introduction as game animal
Northern Mariana Islands Micronesia, Federated states of 1904-1905 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes Wiles et al. (1999) Deliberate introduction as game animal
Northern Mariana Islands Guam 1880 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes Wiles et al. (1999) Deliberate introduction as game animal to Rota
Northern Mariana Islands Northern Mariana Islands 1900 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
Yes Wiles et al. (1999) Deliberate introduction as game animal from Saipan to Rota
Northern Mariana Islands Northern Mariana Islands 1960s Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No Wiles et al. (1999) Deliberate introduction as game animal from Saipan and Rota to Tinian
Philippines Japan before 1853 Animal production (pathway cause) ,
Hunting, angling, sport or racing (pathway cause)
No Miura and Yoshihara (2002); Wiles et al. (1999) Deliberate introduction as game animal from either the Phillipines or Guam

Risk of Introduction

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In recent decades, informal interest has been expressed in conducting additional introductions of Philippine deer in Micronesia, including the Commonwealth of the Northern Mariana Islands (to the island of Aguiguan and one or more of the volcanic islands north of Saipan; Wiles et al., 1999) and the Republic of Palau. These transplants would be done primarily to establish populations for hunting. Without government sanction, these introductions seem unlikely to occur. Philippine deer are currently not listed as a quarantine pest by any Pacific island government. There is no risk of accidental introduction within the Pacific region.

Habitat

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In the Philippines, this species historically ranged from sea level to 2,900 m in primary and secondary forests, with grasslands also used (Taylor, 1934; Sanborn, 1952; Rabor, 1986; Heaney et al., 1998, 2006, 2010; Oliver et al., 2008). Specific habitat types used are lowland moist forest, montane moist forest (including mossy forest), dry forest, seasonally wet/flooded grasslands, and montane grasslands (including grassy clearings in forest) (Heaney et al., 1998, 2010; Oliver et al., 2008; Balete et al., 2011). In Micronesia, Philippine deer occupy most habitats with the exception of urban areas and forests growing on extremely rugged limestone karst (Wiles et al., 1999). Habitats include moist secondary and primary limestone and volcanic forests, scrubby secondary growth, grasslands, freshwater wetlands, and farmlands. In both regions, this species readily enters recently burned grasslands to feed on new plant growth (Wheeler, 1979; Wiles et al., 1999; Heaney et al., 2010).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedCultivated / agricultural land Secondary/tolerated habitat Harmful (pest or invasive)
Managed forests, plantations and orchards Secondary/tolerated habitat Harmful (pest or invasive)
Terrestrial ‑ Natural / Semi-naturalNatural forests Principal habitat Harmful (pest or invasive)
Natural forests Principal habitat Natural
Natural grasslands Principal habitat Harmful (pest or invasive)
Natural grasslands Principal habitat Natural
Wetlands Present, no further details
Scrub / shrublands Secondary/tolerated habitat Harmful (pest or invasive)
Scrub / shrublands Secondary/tolerated habitat Natural

Biology and Ecology

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Genetics

Diploid number (2n) is 64 or 65, and there are 56-58 acrocentric autosomes and 5-6 metacentric and submetacentric autosomes (Hsu and Benirschke, 1973). Wiles et al. (1999) suspected some minor genetic variation among Micronesian populations based on differences in the frequency of occurrence of enlarged antlers on various islands.

Reproductive Biology

The species breeds year-round on Guam, where the occurrences of bucks in velvet, pregnant females, and fawns are relatively constant during all months (Wheeler, 1979). It is also reported to reproduce year-round on Pohnpei (G.J. Wiles, Washington Department of Fish and Wildlilfe, Washington, USA, unpublished data, 2012). One young is born at a time (Wheeler, 1979); twinning has not been reported. Birth interval is not known. The number of recognizable fawns per 100 females was 26:100 and 22:100 in two study areas on Guam from 1964 to 1978 (Wheeler, 1979).

Longevity

A captive individual on Guam lived to 15 years of age (Wheeler, 1979). Average and maximum life spans are poorly known on Guam, where the population is heavily hunted, but Wheeler (1979) suggested that few deer live past 8 years.

Activity Patterns

Philippine deer are primarily active at night. Their loud barking calls occur most often near dawn and dusk in the Philippines (Heaney et al., 2010), but are heard throughout the night on Guam (G.J. Wiles, Division of Aquatic and Wildlife Resources, Guam, USA, personal observation, 1997).

Population Size and Density

Population sizes and densities have not been reported in the Philippines or in most of the introduced range. Many remaining populations in the Philippines are small and fragmented, although deer are still locally common in some remote sites (Oliver et al., 2008; Heaney et al., 2010). Guam’s population size has never been determined. Deer densities are variable on the island, being fairly high to high in many forested locations, especially on military lands, but much lower (probably 0-5.0/km2) near human habitation in civilian areas (G.J. Wiles, Division of Aquatic and Wildlife Resources, Guam, USA, personal observation, 1997). In one 8 km2 area of heavily over-browsed forest, Wiles et al. (1999) suggested a minimum density estimate of 60-80 deer/km2 in the 1990s. A survey in the same area in 2001 suggested much higher densities of as many as 183 deer/km2 (95% confidence interval = 144-215) (S. Vogt, U.S. Navy, Hawaii, USA, unpublished data, 2005). Population trends based on spotlight surveys were described for two parts of the island from 1963 to 1996, with average annual numbers varying from 4.5-16.6 deer/km of road in one area to 0.6-3.0 deer/km in the second area (Wiles et al., 1999). Deer are considered fairly common in much of Rota and some parts of Pohnpei, and rare on Saipan (Wiles et al., 1999).

Nutrition

Very little information on diet is available in the Philippines, although a few observations have been published (Balete et al., 2011). Food records from Micronesia are more extensive and reveal a diverse diet comprised of at least 82 plant species, including trees, shrubs, grasses, herbaceous plants, vines, ferns, and mushrooms (Wheeler, 1979; Wiles et al., 1999). Foliage, fruits, shoots, seeds, and tree bark are eaten. Diet includes agricultural plants and fruits. Relative preferences among food plants remain unknown. Conry (1986) reported differences in dietary quality in northern versus southern Guam, based on fecal concentrations of diaminopimelic acid.

Associations

None.

Environmental Requirements

None.

Natural Food Sources

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Food SourceLife StageContribution to Total Food Intake (%)Details
Adult
Adult
Angiopteris palmiformis Adult
All Stages foliage, seeds
Adult foliage, fruits
Artocarpus mariannensis All Stages foliage, fruits, seeds and bark
Balanophora fungosa Adult shoots
Adult
All Stages seeds
All Stages fruit, seeds
Adult
Adult
Adult
All Stages fruit
Clinostigma ponapense All Stages fruit
All Stages foliage, fruit, seeds
All Stages foliage, seeds
Adult
Adult
All Stages foliage, fruit, seeds
All Stages frond stems, fruit, seeds, bark
All Stages
Adult
Davallia subsolida Adult
Adult
All Stages fruit
Discocalyx megacarpa All Stages seeds
Elatostema calcareum Adult
Elatostema stenophyllum Adult
Eragrostis amabilis Adult
All Stages seeds
Adult
Ficus prolixa Adult
Ficus tinctoria All Stages foliage, fruit
Fungi Adult unidentified mushrooms
Adult
Adult
Adult
Adult
All Stages foliage, seeds
All Stages foliage, fruit
Adult
Adult
Melochia villosissima Adult
Adult
Merrilliodendron megacarpum All Stages fruit
All Stages foliage, fruit, seeds
Adult
Adult
All Stages foliage, fruit
Adult
Ochrosia mariannensis All Stages fruit
Oryza sativa Adult
Palaquium karrak Adult
Adult
All Stages foliage, fruit
Pangium edule All Stages fruit
Adult
All Stages foliage, seeds
All Stages foliage, fruit
Adult
Adult
All Stages fruit
All Stages foliage, seeds
Adult
Adult
Adult
All Stages foliage, bark
All Stages foliage, seeds, bark
Psychotria mariana Adult
Adult
All Stages foliage, seeds
Scleria Adult
Adult
Adult
Adult
All Stages fruit, seeds
All Stages foliage, fruit
All Stages bark
All Stages foliage, seeds
Adult

Climate

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ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
18.6-27.2 5.6

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) 6 22
Mean annual temperature (ºC) 19 28
Mean maximum temperature of hottest month (ºC) 21 37
Mean minimum temperature of coldest month (ºC) 11 25

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Amblyomma Parasite All Stages not specific
Canis lupus familiaris Predator All Stages not specific
Damalinia cordillerai Parasite All Stages to species
Haemaphysalis luzonensis Parasite All Stages not specific
Haemaphysalis psalistos Parasite All Stages not specific
Haemaphysalis rusae Parasite All Stages not specific
Haemaphysalis susphilippensis Parasite All Stages not specific
Haematopinus nigricantis Parasite All Stages to species
Lipoptena rusaecola Parasite All Stages not specific
Ogmocotyle indica Parasite All Stages not specific
Rhipicephalus microplus Parasite All Stages not specific

Notes on Natural Enemies

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Natural factors limiting populations of this species have not been described in the native range, where large and medium-sized carnivores are absent (Heaney et al., 1998, 2010). Introduced feral dogs (Canis lupus familiaris; Canidae) exert some predation pressure in Micronesia (Wiles et al., 1999). The extent of mortality from this cause is unknown, but is probably relatively minor.

Nine species of ectoparasites (including six ticks) and one endoparasite are known to infect Philippine deer (Eduardo, 2000). Individuals with heavy infestations of the tropical cattle tick Rhipicephalus microplus (Ixodidae) are commonly observed on Guam (Wheeler, 1979; Wiles et al., 1999). These deer often show hair loss and open sores on their necks and chests that probably result from extensive rubbing on trees and rocks to dislodge the ticks. It is unknown whether severe tick loads may predispose deer to dog predation or other mortality.

Means of Movement and Dispersal

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Eight introductions of Philippine deer have been documented, all to Pacific islands measuring 540 km2 or less in size (Wiles et al., 1999; Miura and Yoshihara, 2002). All introductions were intentional, occurred between the 1770s and 1960s, and made by transporting animals via ship. All were conducted to bring a food source to the islands and possibly to establish a resource for hunting. None were considered illegal at the time they were made, and most were performed under the sanction of colonial governments. No serious attempts to conduct additional introductions have occurred since 1966. Distances between source and recipient islands ranged from a minimum of 5 km (from Saipan to Tinian) to a maximum of about 2,400 km (from Luzon to Guam).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Animal productionDeliberately introduced 8 times to Pacific islands (1770-1960s) - islands less than 540km2 in size Yes Yes Miura and Yoshihara, 2002; Wiles et al., 1999
Hunting, angling, sport or racingDeliberately introduced 8 times to Pacific islands (1770-1960s), one introduction every 28 years Yes Yes Miura and Yoshihara, 2002; Wiles et al., 1999

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Ship structures above the water lineSmall numbers of live adult animals deliberately transported aboard ships Yes Yes Miura and Yoshihara, 2002; Wiles et al., 1999

Impact Summary

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CategoryImpact
Cultural/amenity Positive
Economic/livelihood Positive and negative
Environment (generally) Negative

Economic Impact

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The introduction of Philippine deer to Micronesia has produced negative and positive economic impacts, all but one of which are currently relatively small. Agricultural damage from deer on Guam, Rota, and Pohnpei was greater in the past (Dybas, 1948; Jackson, 1962; Wiles et al., 1999), when farming was much more important to island economies. Minor damage to melons, cucumbers, bananas, sweet potatoes, corn, and beans continues to the present on these islands. The Guam Division of Aquatic and Wildlife Resources issued 5-10 deer control permits to farmers annually during the 1990s. Philippine deer also caused significant damage to agriculture in the Ogasawara Islands during the late 1800s (Miura and Yoshihara, 2002).

The negative environmental effects of overbrowsing of forest plants and grassland fires set by deer hunters has not been assessed in economic terms, but includes damage to coral reefs from siltation (a major impact on Guam) and declines in the availability of medicinal plants and various other forest products (minor impact).

The availability of venison, which is eaten by hunters’ families and friends or is sold legally or illegally, produces some minor economic benefits. Legal harvests averaged more than 600-1,000 deer per year on Guam and 20-40 deer per year on Rota from 2004 to 2011 (JRMNRS, 2012; R. Benford, Department of Fish and Wildlife, Commonwealth of the Northern Mariana Islands, USA, personal communication, 2012). Illegal harvest probably exceeds legal harvest on Guam, Rota, and Saipan (Wiles et al., 1999). Harvest is not regulated on Pohnpei.

Environmental Impact

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Impact on Habitats

The most serious impacts resulting from the introduction of Philippine deer to Micronesia are those relating to the environment. When present in moderate to high densities, the species has been documented to cause substantial damage to native plant communities on Guam, Rota, and Pohnpei (Wiles et al., 1999). Damage can be comparable in severity to that caused by feral pigs (Sus scrofa) and feral goats (Capra hircus) on other oceanic islands.

Ecological impacts have been by far the greatest on Guam, where extensive damage to ecosystems has occurred since at least the early 1980s (Wiles et al., 1999). In many parts of the island, deer and feral pigs both contribute to the damage. However, deer are much more numerous than pigs in parts of northern Guam, and therefore are responsible for most of the observed changes in forest composition and structure in these areas. Although these changes have been poorly quantified to date, it is apparent that overbrowsing by deer has caused elimination of most herbaceous ground cover and low epiphytic growth over large areas; a browse line on some trees and shrubs; poor or no regeneration in many woody species, causing localized disappearances of some trees and shrubs; proliferation of three apparently unpalatable native trees, Guamia mariannae, Aglaia mariannensis, and Ochrosia mariannensis; and major decreases in plant diversity (Conry, 1988; Schreiner, 1997; Wiles et al., 1999; Wiles, 2005). The degradation of native forest by deer has also prevented forest regeneration on the Guam National Wildlife Refuge lands, including overlay lands of the US Navy (A. Brooke, Navy Natural Resources, Guam, personal communication, 2012). Furthermore, deer have helped to promote the spread of invasive weeds through the removal of natural ground cover and dispersal of seeds.

Herbivory by deer caused obvious damage to native forests on Rota in the 1970s and 1980s and Pohnpei in the mid-1900s (Dybas, 1948; Wiles et al., 1999). These negative impacts declined in the following decades, but have not been recently reassessed on either island.

Deer presence has also led to the problem of poachers regularly burning grassland fires to attract deer to the new plant growth (Wiles et al., 1999). This occurs most commonly on Guam and has happened there for more than a century. From 1986 to 1995, an average of 790 fires totalling 2,133 ha occurred annually, with most started by deer poachers in southern Guam (D.T. Limtiaco, Guam Division of Forestry and Soil Resources, Guam, USA, personal communication, 1997.). Fires of this type are less frequent on Rota, Saipan, and Pohnpei. The fires cause increased soil erosion that harms the islands’ freshwater streams and fringing coral reefs. They also burn into the edges of bordering forest, resulting in a gradual loss of forest cover.

Deer numbers are typically higher in the more remote parts of Guam, Rota, and Pohnpei, many of which represent areas of high biodiversity and conservation value. These sites include the following protected areas: 1) Guam: Guam National Wildlife Refuge, Anao Conservation Reserve, Cotal Conservation Reserve, Guam Territorial Seashore Park and Bolanos Conservation Reserve; 2) Rota: Sabana Heights Wildlife Conservation Area, I'Chenchon Park Bird Sanctuary and Wedding Cake Wildlife Conservation Area; and 3) Pohnpei: Watershed Forest Preserves.

Impact on Biodiversity

Philippine deer have contributed to the declines of at least several native plant and animal species. These include the trees Artocarpus mariannensis and the IUCN critically endangered and US federally listed endangered Serianthes nelsonii , which suffer excessive seedling mortality and/or seed predation from deer on Rota and Guam, respectively (Wiles et al., 1996; Wiles, 2005). Although empirical evidence is lacking, chronic deer herbivory also appears to have played a role in the localized declines of a variety of other plants on Guam, such as the IUCN endangered Cycas micronesica (Wiles et al., 1999; G.J. Wiles, Division of Aquatic and Wildlife Resources, Guam, USA, personal observation, 1997). The elimination of two plants, Elatostema calcareum and Procris pedunculata, in many areas of Guam due to heavy deer and pig feeding may be related to the rarity of the butterfly Hypolimnas octocula, which is endemic to Guam and Saipan (I.H. Schreiner, University of Guam, USA, personal communication, 1998). Degraded forest conditions have undoubtedly altered animal communities as well.

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Cycas micronesicaEN (IUCN red list: Endangered) EN (IUCN red list: Endangered)GuamHerbivory/grazing/browsing
Serianthes nelsoniiCR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered speciesGuam; Northern Mariana IslandsHerbivory/grazing/browsingWiles et al., 1996

Social Impact

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Deer are a sought-after game animal and food item on Guam, Rota, and Saipan, where venison is a favoured food at social gatherings.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Long lived
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Increases vulnerability to invasions
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Negatively impacts aquaculture/fisheries
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Pest and disease transmission
  • Herbivory/grazing/browsing
  • Parasitism (incl. parasitoid)
  • Trampling

Uses List

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General

  • Sociocultural value
  • Sport (hunting, shooting, fishing, racing)

Human food and beverage

  • Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

Similarities to Other Species/Conditions

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Philippine deer do not overlap geographically with other deer species anywhere in their native or introduced ranges. In comparison with the two other deer species occurring in the Philippines, they are similar in size with Visayan spotted deer, but lack spotting and have broader skulls and coarser pelage (Nowak, 1999). They are slightly larger in size than Calamian deer (Axis calamiensis; restricted to the Islands of Busuanga, Culion, and Calauit), but that species is richer brown in colour and has a white tail tip, spotted fawns, and often a wider antler spread (Heaney et al., 2010). Among other species in the genus Rusa, Philippine deer are somewhat smaller in size and have a different antler shape than rusa deer (R. timorensis), and are substantially smaller than sambar (R. unicolor) (Nowak, 1999).

Prevention and Control

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Public Awareness

Increased awareness of the actual or potential ecological damage caused by Philippine deer is greatly needed among government officials, hunters, the public, and conservation groups in Micronesia, especially on Guam. Efforts to reduce or eradicate deer populations on Guam and Rota conflict with the goals of the hunting community, who support the retention of sizeable deer populations. This makes control efforts more difficult to implement. Military officials on Guam have also been apathetic toward undertaking deer reductions on their lands to limit ecological damage. 

Physical/Mechanical Control

Philippine deer have proliferated at times on Guam and other Micronesian islands when managed under strictly regulated hunting programs (Guam, Rota) and/or because some populations inhabit areas with limited hunter access due to land closures (e.g. U.S. military bases on Guam) or rough terrain (e.g. central Rota). Wiles et al. (1999) identified management options for controlling deer populations in the region, but these recommendations have not been implemented to date, with the exception of one military base on Guam, which has increased hunting and drafted an ungulate management plan (JRMNRS, 2012).

Philippine deer are easily controlled through liberalized or unregulated hunting regimes, wherein bag limits and seasonal restrictions are expanded or eliminated, and night hunting might be allowed (Wiles et al., 1999). This is most appropriate on Guam and Rota, where only one antlered male can currently be killed per 3 or 4 month hunting season, with a few exceptions. Year-round protection of deer should be ended on Saipan and protective regulations should not be enacted on Pohnpei. At present, illegal hunting is beneficial in controlling populations on Rota, Saipan, and parts of Guam. Deer management on Guam’s military lands is somewhat more problematic because of restricted public access, but control of deer populations could be easily accomplished by hiring companies specializing in ungulate control to conduct shooting programs. Fencing areas of ecological value is a potentially useful tool, but is expensive due to the initial cost of construction and the need for constant maintenance.

Ecosystem Restoration

Reducing or eradicating deer populations should immediately benefit forest recovery on all islands. However, on Guam, where ecosystems are particularly degraded for a variety of reasons, additional steps may be necessary to accomplish recovery, such as outplanting or reseeding native plant species.

Gaps in Knowledge/Research Needs

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Basic research is needed on all aspects of the biology and management of Philippine deer. Studies investigating the ecological impacts of the species in Micronesia would also be of great value.

References

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Balete DS; Alviola PA; Duya MRM; Duya MV; Heaney LR; Rickart EA, 2011. The mammals of the Mingan Mountains, Luzon: evidence for a new center of mammalian endemism. Fieldiana: Life and Earth Sciences, 2:75-87.

Conry PJ, 1986. Division of Aquatic and Wildlife Resources Annual Report, Fiscal Year 1986. Mangilao, Guam: Guam Department of Agriculture, 114-118.

Conry PJ, 1988. Management of feral and exotic game species on Guam. Transactions of the Western Section of the Wildlife Society, 24:26-30.

Dybas HS, 1948. Comments on conservation in Micronesia. In: Conservation in Micronesia [ed. by Coolidge, H. J.]. Washington, DC, USA: National Research Council, 58-59.

Eduardo SL, 2000. Damalinia cordillerai n.sp. (Mallophaga: Trichodectidae) and two other previously known arthropod parasites of the Luzon sambar deer, Cervus (Rusa) philippinus Smith, 1827 (Mammalia: Artiodactyla: Ruminantia). Philippine Journal of Veterinary Medicine, 37(2):72-81.

Grubb P, 2005. Artiodactyla. In: Mammal species of the world: a taxonomic and geographic reference [ed. by Wilson, D. E. \Reeder, D. M.]. Baltimore, USA: Johns Hopkins University Press, 637-722.

Grubb P; Groves CP, 1983. Notes on the taxonomy of the deer (Mammalia, Cervidae) of the Phillipines. Zoologischer Anzeiger, 210:119-144.

Heaney LR; Balete DS; Dolar ML; Alcala AC; Dans ATL; Gonzales PC; Ingle NR; Lepiten MV; Oliver WLR; Ong PS; Rickart Tabaranza Jr EABR; Utzurrum RCB, 1998. A synopsis of the mammalian fauna of the Philippine Islands. Fieldiana: Zoology, 88:1-61.

Heaney LR; Dolar ML; Balete DS; Esselstyn JA; Rickart EA; Sedlock JL, 2010. Synopsis of Philippine mammals. Chicago, USA: Field Museum of Natural History and Philippine Department of Environment and Natural Resources, Protected Areas and Wildlife Bureau. http://archive.fieldmuseum.org/philippine_mammals/

Heaney LR; Gonzales PC; Utzurrum RCB; Rickart EA, 1991. The mammals of Cataduanes Island: implications for the biogeography of small land-bridge islands in the Philippines. Proceedings of the Biological Society of Washington, 104(2):399-415.

Heaney LR; Tabaranza Jr BR; Rickart EA; Balete DS; Ingle NR, 2006. The mammals of Mt. Kitanglad Nature Park, Mindanao, Philippines. Fieldiana: Zoology, 112:1-63.

Hsu TC; Benirschke K, 1973. An atlas of mammalian chromosomes. Volume 7. Berlin and Heidelberg, New York, USA, Springer-Verlag., German Federal Republic xvi + 248 pp.

Jackson WB, 1962. Area of study. Bulletin of the B.P. Bishop Museum, 225:14-20.

JRMNRS, 2012. Draft Joint Region Marianas; Andersen Air Force Base ungulate management plan. Guam: Joint Region Marianas Integrated Natural Resources Management Plan, US Navy, 70.

Meijaard E; Groves CP, 2004. Morphometrical relationships between South-east Asian deer (Cervidae, tribe Cervini): evolutionary and biogeographic implications. Journal of Zoology, 263(2):179-196.

Miura S; Yoshihara M, 2002. The fate of Philippine brown deer Cervus mariannus on the Ogasawara Islands, Japan. Mammalia, 66(3):451-452.

Nowak RM, 1999. Walker's mammals of the world. Baltimore, Maryland: The Johns Hopkins University Press.

Oliver W; MacKinnon J; Ong P; Gonzales JC, 2008. Rusa marianna. IUCN red list of threatened species, Version 1, 2012. Gland, Switzerland: International Union for Conservation of Nature. http://www.iucnredlist.org

Oliver WLR, 1993. International Zoo Yearbook, 32. 131-144.

Pitra C; Fickel J; Meijaard E; Groves PC, 2004. Evolution and phylogeny of old world deer. Molecular Phylogenetics and Evolution, 33(3):880-895.

Rabor DS, 1986. Guide to Philippine flora and fauna. Volume 11, Birds and mammals, 11. Quezon City, Philippines: Ministry of Natural Resources and University of the Philippines, 213.

Rickart EA; Heaney LR; Heideman PD; Utzurrum RCB, 1993. The distribution and ecology of mammals on Leyte, Biliran, and Maripipi islands, Philippines. Fieldiana: Zoology, 72:1-62.

Sanborn CC, 1952. Philippine zoological expedition, 1946-1947; Mammals. Fieldiana (Zoology), 33:87-158.

Schreiner IH, 1997. Demography and recruitment of selected trees in limestone forest of Guam in relation to introduced ungulates. Micronesica, 30(1):169-181.

Taylor EH, 1934. Philippine land mammals. Bur. Sci. Monogr. (Manila), 30:548.

Wheeler ME, 1979. The biology of the Guam deer. Division of Aquatic and Wildlife Resources Technical Report, 3. Mangilao, Guam: Division of Aquatic and Wildlife Resources, 53.

Whitehead GK, 1993. The Whitehead encyclopedia of deer. Shrewsbury, UK: Swan Hill Press, 604.

Wiles GJ, 2005. Decline of a population of wild seeded breadfruit (Artocarpus mariannensis) on Guam, Mariana Islands. Pacific Science, 59(4):509-522.

Wiles GJ; Buden DW; Worthington DJ, 1999. History of introduction, population status, and management of Philippine deer (Cervus mariannus) on Micronesian islands. Mammalia, 63(2):193-215.

Wiles; GJ; Schreiner IH; Nafus D; Jurgensen LK; ; Manglona JC, 1996. The status, biology, and conservation of Seranthes nelsonii (Fabaceae), an endangered Micronesian tree. Biological Conservation, 76(3):229-239.

Links to Websites

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WebsiteURLComment
Synopsis of Philippine mammalshttp://archive.fieldmuseum.org/philippine_mammals/species/SP_56.asp

Organizations

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USA: DFW CNMI Division of Fish and Wildlife, DFW Lower Base, PO Box 10007, Saipan, MP 96950, http://www.dfw.gov.mp/Wildlife/Wildlife%20Research.html

USA: GDAWR Guam Division of Aquatic and Wildlife Resources, 163 Dairy Road, Mangilao, GU 96913, GUAM, http://www.guamdawr.org/

Contributors

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28/08/2012 Original text by:

Gary J. Wiles, Washington Depeartment of Fish and Wildlife, 600 Capitol Way North, Olympia, Washington 98501, USA  

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