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Camiguin Island, with an area of ca. 265 km2 and maximum elevation of ca. 1620 m, lies about 10 km north of Mindanao but is isolated from Mindanao by a deep (385 m) channel. It originated from volcanic activity as a dryland island not earlier than 1 million years ago, but most growth of the island has occurred within the past 340,000 years. Current landforms are dominated by large, scenic volcanic peaks, several of which are active. Lowland rain forest originally occurred up to about 1100 m elevation, with montane rain forest from 1100 m to about 1350 m and mossy forest from 1350 m to the peaks. By the mid-1990s, deforestation had removed most natural vegetation below about 600 m, with degree of disturbance to forest decreasing with elevation and ending at about 1250 m. The climate is tropical, with rainfall of 2–3 m per year in the lowlands and probably about 7.5 m near the peaks. Mammal and/or bird specimens are available from 18 sites from the 1960s and 1990s; these sites are here located and described to the extent possible. Given the presence of two endemic species of mammals (one described in this volume), one endemic bird (described in this volume), and previously described endemic plants and a frog, Camiguin is one of the smallest but most distinctive centers of biodiversity in the Philippines and should be a priority site for conservation. The remaining forest on Camiguin is essential habitat for these unique species, but it is also essential for watershed protection and control of floods and landslides, and it contributes significantly to the tourism trade that provides substantial income on the island. Deforestation for logging and agriculture and overhunting are current threats. A protected area on the island should include the full range of original habitat diversity, which would encompass both the existing high-quality forest at upper elevations and also significant tracts of disturbed but natural lowland forest, especially along rivers and streams, that should be allowed to regenerate in the future.
An inventory of the mammals of Camiguin Island conducted in 1994 and 1995 documented the presence of a previously unknown species of Philippine forest mouse of the endemic Philippine genus Apomys, which is here named and described. Based on molecular data, the new species is most closely related to two species (A. hylocoetes and A. insignis) from Mindanao Island and to an unnamed species from Leyte, Biliran, and Bohol islands. The new species is diagnosed in comparison to its three closest relatives on the basis of slightly browner and less russet fur, slightly greater size overall, a moderately long and broad hind foot with small plantar pads, large tail scales, slightly narrower zygomatic width and mastoid breadth, deep rostrum of moderate length, a long orbit and braincase, narrow palate, large incisive foramina, short distance from the posterior edge of the incisive foramina to the anterior edge of the first upper molar, bony palate that extends well to the posterior of the posterior edge of the last upper molar, bullae that are more strongly oriented toward the cranial midline axis, third upper molar without a conspicuous anterolabial cusp, and a number of more subtle features. It is one of two species of mammals now known to be endemic to Camiguin, the other being Bullimus gamay (Rickart et al., 2002). Both are common in rain forest on Camiguin Island at upper elevations. The presence of two endemic mammals on this small (265 km2) island is remarkable; there are no smaller islands in the Philippines known to support endemic mammal species.
Biodiversity surveys in the 1960s and 1990s on Camiguin Island, a geologically young, volcanically active oceanic island surrounded by deep water, have demonstrated the presence of 24 species of land mammals. Three species (one insectivore and two rodents) are not native to the Philippines, but all others (one insectivore, 12 bats, one monkey, four rodents, two small carnivores, and one ungulate) are indigenous. Among those captured in the 1990s were two previously unknown species of murid rodents in the genera Apomys and Bullimus that are endemic to Camiguin. The discovery of two new species on such a small island (ca. 265 km2) is remarkable; Camiguin is currently the smallest island in the Philippines known to have unique species of mammals. Total species richness of nonvolant mammals on Camiguin is low, but relative to islands that were once part of Pleistocene Greater Mindanao, Camiguin is not depauperate. However, its fauna is not ecologically balanced in the same way as the faunas of the islands that were part of Greater Mindanao: ground-living shrews (Crocidura) and rodents (Apomys, Bullimus, Crunomys, and Rattus) from lowland forest, along with some large mammals (Macaca, Paradoxurus, and Sus) are well represented on Camiguin, but all the arboreal small mammals that characterize lowland forest on Mindanao (Sundasciurus, Exilisciurus, Cynocephalus, and Tarsius), ground-living small mammals from montane habitats (Urogale, Podogymnura, Batomys, Limnomys, and Tarsomys), and one large mammal (Cervus) are absent. Additionally, at least two genera of fruit bats (Haplonycteris and Megaerops) that are fairly common in lowland rain forests on Mindanao are absent on Camiguin. The presence of some nonvolant mammals demonstrates that dispersal across the deep but narrow intervening channel takes place, but the presence of two species endemic to Camiguin and the absence of other species that are present on nearby Mindanao implies that dispersal probably is rare. The Asian house shrew (Suncus murinus) was remarkably abundant in primary forest at high elevation; this species has also been found to be abundant in montane primary forest on Negros Island, which also has low total species richness. Species richness of small nonflying mammals was greatest at fairly high elevation.
A new species of Hanging-Parrot or Colasisi, Loriculus, is described from a series of 23 specimens (19 males, 4 females) collected in the 1960s on Camiguin Island, Camiguin Province, Philippines, at elevations between 300 and 1350 m. The new species lacks sexual dimorphism in plumage coloration, which distinguishes it from all other members of the L. philippensis group and all other Loriculus. The overall color pattern of the new species appears most like females of L. p. worcesteri and L. p. apicalis but differs in plumage characteristics (the width and extension of the orange-scarlet crown patch, the amount and intensity of blue in the face and thighs, and the intensity of the blue in the tail above inner edges and the tail below). In addition, males of the new species are larger than males of nearby populations of L. philippensis, having significantly longer tails and wing chords. Nothing is known about the habits of the new species; however, the small size of the island of Camiguin, coupled with extensive deforestation, makes the status of the new species a significant conservation concern.
Fifty-five species of resident breeding and two species of migratory land birds have been documented on Camiguin Island, including one bittern, one eagle, one junglefowl, two rails, eight doves and pigeons, one parrot, three cuckoos, one owl, three swiftlets, one dollarbird, two kingfishers, one bee-eater, one hornbill, one pitta, one triller, two bulbuls, one crow, four thrushes, three warblers, six flycatchers, one pipit, one wood swallow, two starlings, three sunbirds, two flowerpeckers, two white-eyes, and two munias. At least seven species reported here are first records for Camiguin. Ten species are widespread Philippine endemics, two are near-endemics, and one (Loriculus camiguinensis, described in this volume) is endemic to Camiguin. Additionally, four endemic subspecies are recognized from Camiguin, Ixos everetti catarmanensis, Hypothymis azurea catarmanensis, Diceum trigonostigma isidroi, and Zosterops nigrorum catarmanensis. While this list is not comprehensive, the presence of 57 species demonstrates that many species were able to cross a narrow but permanent sea channel, and the presence of four endemic subspecies and one endemic species indicates that some genetic differentiation has resulted.