The Impact of Deforestation on Birds of Cebu, Philippines
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Jan.] 37 1959a THE IMPACT OF DEFOKESTATION ON BIKDS OF CEBU, PHILIPPINES, WITH NEW KECOKDS FOK THAT ISLAND BY D. S. RABOR Cebu Island, in the central Philippines, is one of the ten large islandsof the archipelago,with an area of about 4390 squarekilo- meters. Though hilly, it reachesno great height, the maximum eleva- tion being 1013meters in Mr. Cabalasanin the central part. The islandwas probably originally forested. Before the comingof the Spaniards,in 1521,the populationprobably raised only rice as a food crop. This could be grown only on favorable areas in the narrow coastalplain. Thus deforestationwas limited. With the arrival of the Spaniards,and the introduction of corn, sweetpotato and cassava(all native to tropical America),which could be raised more widely on lowlandsand hills, deforestationcontinued. Within historictimes Cebu has been densely populated compared with nearby islands. Before populationpressure the forestsdisappeared. This deforestationwas hastened by the wastefulmethod of shiftingculti- vation (kaingin system)practiced, in which land is cleared,planted to cropsfor a few seasons,then abandonedfor a new clearing. When ornithological collectingwas started on Cebu in 1872, the forestswere limited to patchesin a few partsof the island. In 1906, when McGregor and his assistantscollected on Cebu, they already had difficultyin finding forestsin which to collect. For some decadesthe Bureau of Forestry has been carrying on reforestationprojects on Cebu, the most notable of thesebeing in Toledo and in the hills near the water reservoirof Cebu City at BuhisanDam. Up to 1941,the Bureau'sefforts were progressingand new forestswere being developed. The SecondWorld War broke out and when it endedin 1945,nothing much was left of the govern- ment-createdforests. The peoplehad clearedmost of them as well as the beginningluxuriant growthsin many placesin the hills and mountainsof Cebu. Today, the Bureau of Forestryis again very seriouslycarrying on reforestationwork in severalparts of Cebu. In our work from SillimanUniversity in Cebu,begun in 1947 (see below) and in aerialsurvey of the island,we havebeen unable to find any patchesof originalforest, and the bestbird area we found was the newlydeveloped forest near Buhisan Dam. ORN•O•.OGICA•. His•roR¾ oF CEBU Severalcollectors have worked on Cebu. Among them were A. B. Meyer in 1872, J. B. Steere (First SteereExpedition) in 1874-75, [- Auk 38 R^noR,Impact o! De[orestationon Birdso! Cebu I-Vol.76 J. Murray (ChallengerExpedition) in 1874,A. H. Everettin 1877, Secondsteere Expedition (J. B. Steere,F. S. Bourns,E. L. Moseley, D.C. Worcester)in 1888, Menage Expedition (F. S. Bournsand D.C. Worcester)in 1892,and R. C. McGregorin 1906. SinceMc- Gregor'swork on Cebu in 1906, no seriousornithological collecting hasbeen done on this island until 1947,when my students,assistants and I started to make collections of the land vertebrates on Cebu. One objectivewas to find out how the land vertebratefauna, espe- cially the birds, have fared in the face of the excessivedeforestation sufferedby this island during the twentieth century. In this study, Mr. Filomeno Erapeso,a Field Assistantof the Biology Department of Silliman University,has aided me very efficiently. Collectingwas carried on periodicallyin severalplaces on the island. To date about 1100bird specimens,among other land verte- brates,have been collectedon Cebu. The collectionsare at present in variousinstitutions, the bulk of them in the ChicagoNatural His- tory Museum (CNHM) and in Silliman University (SU), and a few in the Yale PeabodyMuseum (YPM). R. C. McGregor (1909. "A Manual of Philippine Birds,") lists 154 speciesfrom Cebu, of which 123 are resident,30 migrant, and 1 of doubtfulstatus. D.S. Rabor (1952. Auk, 69 (3): 253-257) added two new recordsof residentforms, raising the total to 156. The presentpaper reports 10 new bird recordsfor Cebu, which include 6 residentand 4 migrant forms. This raisesthe total number of birds known from Cebu to 166, of which 131 are resident, 34 migrant, and one of doubtful status. Of the 10 new records, 8 are representedby actualcapture of specimens,and two by sightrecords on various occasions. Three interestingaspects of the bird life on Cebu Island are dis- cussedbelow: a. the statusof the 10 endemicforms; b. forestspecies; c. new records. The vernacular names follow in general those in Delacour and Mayr, 1946,"Birds of the Philippines,"(MacMillan Co.). ENDEMIC FORMS Ten endemicforms (seelist below) have beenrecognized for Cebu. All presumablywere forest birds. We were able to find only one of these,the Black Shama,Copsychus cebuensis. The followingis a list of the endemicbirds with their presentstatus: Phapitreronamethystina Irontails Bourns and Worcester.Amethyst Brown Fruit Dove.--Collectedby Bournsand Worcester,1892, and not found sincethen. Pre- ferred hill and mountain original forests. •9•9a I•o•, Impacto)•De)•orestation onBirds o)• Cebu 39 Loriculusphilippensis chrysonotus Sclater. PhilippineHanging Parakeet.--Col- lectedby: Meyer,Steere, Everett, Steere Expedition (second), Menage Expedition, McGregor.Not foundsince McGregor collected it in 1906. The speciesprefers originalforests of the lowlandsand hills, but alsoranges in the coconutgroves and secondgrowth. Breeding,however, takes place in original forests,at the edgesof same,or in forestclearings. This speciesis one of the commonbirds that are kept as cagepets throughout the Philippines. However,in recentyears, the birds that I have seenon Cebu that werekept as cagebirds, were either the Mindanaorace, L. p. apicalis,or the Negrosrace, L. p. regulus. Both forms are very abundant in their home islands. Regularpeddlers bring them in boatsfrom Mindanaoand Negrosand sell them in Cebu City. Since 1947, I have not collected,nor definitely observed,the Cebu race of the species. On severaloccasions, however, I heard the very characteristicmusical notesof the speciesin the coconutgroves in southernCebu. But then, nobody can be sure of the particularrace of the bird that might be singingat any one time becausethe songsof the variousraces are similar. I heard the notes of the specieson Siquijor Island and thought that at last we would have the chance to collectthe rare Siquijor race,L. p. siquijorensis.The bird was collectedand to our amazement,it turned out to be L. p. regulus of Negros. It must have been a cageescape, one of many cagebirds of this speciesbrought over from Negros. Coracinastriata cebuensisGrant. Barred Graybird.--Collectedby: Everett, Bourns and Worcester,McGregor. Not found sinceMcGregor collected it in 1906. Preferred original forestsof the lowlands,hills and mountains,but also ranged in the secondgrowth. Coracina caerulescensalterurn Ramsay. Black Graybird.--Collectedby: Everett, Bourns and Worcester, McGregor. Not found since McGregor collected it in 1906. Preferred original forestsin the hills and mountains. Microscells siquijorensis monticola Bourns and Worcester. Mottled-breasted Bulbul.--Collected by: Bourns and Worcester, McGregor. Not found since McGregor collected it in 1906. Said to live in mountain forests. Its congener, M.p. philippinus, is still very commonin the hills and mountains,among second growth patchesand even in coconutgroves. Copsychuscebuensis Steere. Black Shama.--Collectedby: Steere Expedition, Bourns and Worcester,McGregor, and Empeso. Lives in original forests,dense thickets,and densesecond growth mixed with thickets. Its adaptation to second growth and thickets will help much in its survival on the island. F. Empeso collecteda singlespecimen, a male with the testesenlarged, on July 16, 1956, in dense secondgrowth mixed with thickets. Its congener,G. saularismindanensis, is a very commonbird in secondgrowth, bamboogroves, hedge growthsin cultivated areas,and even in gardens. Dicaeum trigonostigmapallidius Bourns and Worcester. Orange-breasted Flowerpecker.--Collectedby: Everett, Bournsand Worcester,McGregor. Not found since McGregorcollected it in 1906. Lived in original forestsin the lowlands, hills and mountains, especiallyclose to the edges, but also ranged in second growthand clearings. McGregor (1907,Phil. Journ. Sci.,II A, p. 307) basedon his observationsof the specieson Cebu in 1906,writes: "This speciesis the most commonmember of the family Dicaeidaein Cebu." [- Auk 40 RABOl•,Impact of Deforestationon Birdsof Cebu •_Vol.76 Dicaeum quadricolor Tweeddale. Four-Colored Flowerpecker.--Collectedby: Everett, Bourns and Worcester, McGregor. Not found since McGregor collected it in 1906. Lived in original forests in the lowlands and hills. Its congener, D. a. australe(papuense of authors), remainsvery abundantall over the island. Zosteropseveretti everetti Tweeddale. Everett'sWhite-eye.--Collected by: Everett, SteereExpedition, Bourns and Worcester,McGregor. Not found since McGregor collected it in 1906. Lived in lowland and hill forests and also ranged in second growth. Its congener,Z. everertl slqUi]orensls,on Siquijor Island, is still a fairly com- mon bird in second growth patches. Oriolus xanthonotusassimilis Tweeddale. Dark-throated Oriole.--Collectedby: Everett, Bourns and Worcester, McGregor. Not found since McGregor collected it in 190õ. Bourns and Worcester (in McGregor, 1909, A Manual of Philippine Birds, p. 701) write of this speciesthus: "0. assimilisis exceedinglycommon in the small amount of forest left in Cebu." This observation was made in 1892. FOREST SPECIES Some forest speciesthat we found in the courseof our work on Cebu include the following: Ducula aenea aenea