The Auk 110(3):529-540, 1993 USE OF AN EXOTIC TREE PLANTATION BY BORNEAN LOWLAND FOREST BIRDS SHAIBAL S. MITRA • AND FREDERICK H. SHELDON 2 1Committeeon EvolutionaryBiology, University of Chicago,Chicago, Illinois 60637, USA; and 2Departmentof Ornithology,Academy of Natural Sciences, 1900 BenjaminFranklin Parkway, Philadelphia, Pennsylvania 19103, USA ABSTRACT.--DuringMay to July 1982,we surveyedbirds in primary forestand in different- aged grovesof the exotictree Albiziafalcataria at SabahSoftwoods, a lowland tree plantation in Sabah,East Malaysia (formerly British North Borneo).We found that the Albiziawas in general attractive to many native birds. About 60% of primary-forestspecies used the plan- tation, and the frequencyat which individuals were observedin the oldestgroves was almost twice that of nearby primary forest. The Albiziaattracted birds because,as an extremely fast- growing legume with thin leaves,it permitted the rapid development of a well-structured secondaryforest. It alsowas heavily infestedwith pestinsects, which providedan abundant food source. Despite its apparent richness,however, the Albizia lacked several important featuresof natural forest(e.g. canopyfruits and nestholes). As a result,some primary-forest bird groupswere poorly represented(e.g. large canopy frugivores and flycatchers)and others could make only limited use of the plantation(e.g. woodpeckers).In addition, the Albiziais expectedto loseits diversityas the plantationas a whole ages.Many of the plantationbirds were transientsfrom nearbyforest that visited daily to feed, and someprobably had been displacedby intense logging. The number of daily transientsshould decreaseas primary forestrecedes due to logging and development.Refugee species diversity should sufferfrom attrition as the plantation is cropped and predation and age take their toll. Received9 March 1992, accepted20 November1992. As THERESULT of development,many tropical forestcommunities (e.g. as a sourceof food or rain foreststhroughout the world face rapid competitors)?Answers to such questionsare and generallydestructive change. One form of neededbecause they not only bear on issuesof tropical land development that has become in- tropicalcommunity ecology, but they relatedi- creasinglypopular in the last 20 years is the rectly to practicalproblems of plantation man- planting of exotic, fast-growingtrees for chip agementand the conservationof organismal and pulp production.Tracts of primary rain for- diversity.Although plantationsare inevitable, estin Asia,Africa, and the Neotropicsthat have they canbe developedto preserveand exploit been exploited for timber subsequentlyhave natural forests.For example,plantations that been clearedand replacedwith plantationsof are intercalatedwith or surroundedby natural treessuch as Eucalyptus deglupta, Gmelina arborea, forestalmost certainly benefit from biological Albiziafalcataria, Acacia manglum, Pinus carabaea, control of infesting pests(e.g. insectsand ro- P. oocarpa,and Anthocephaluschinensis. Unlike dents)by forest-dwellingpredators. The useof agricultural crops, such plantations do not re- forestconservation in plantationmanagement quire good soilsor intensive management(e.g. and the influenceof plantationson forestcom- of understorygrowth). Thus, they offer an at- munitieswill dependupon many potentialfac- tractive alternative for sustainedyield of rev- tors, including the types,ages, and mixture of enues. trees that are cultivated, crop rotation, prox- Although the prospectof sterile monocul- imity of primaryforest, plantation physiogno- tures replacing diverse, rich forestshas raised my (e.g. presence of streams, cliffs, etc.), and concerns(e.g. Andrews 1973, Wells 1985, Shel- timing and complexityof pestinfestations. don 1986), the ecologicalconsequences of this To understand elements of the interaction be- type of land use have received little attention, tween plantation and forest bird communities, and many basic questions remain to be an- we censused birds at Sabah Softwoods Planta- swered. In particular, how will native plants tion in Sabah,East Malaysia (formerly British and animals respond to plantations,and how North Borneo)during May to July 1982. Ours will plantationcommunities influence adiacent is one of only a few suchstudies that have been 529 530 MITRA^NO SHELDON [Auk, Vol. 110 TABLE1. Dates and times of surveys. of our survey, about 25,000 ha of a 61,000-ha concessionhad been replanted,principally with No. the exotic treesAlbizia falcataria, Acacia mangium, Plot type Plot sur- Early/ (age) no. veys Dates late" Gmelinaarborea, and Eucalyptusdeglupta. Anoth- er 3,300ha were planted with agriculturalcrops Primaryforest 1 2 10, 15 June 2/0 such as cocoa and coffee (Duff et al. 1984). Cir- 2 ! 10 June 0/! cumscribedstands of primary forest persisted Albizia about 1 to 2 km from the plantation in 1982, !975(7years) ! 8 28 May-25 July 4/4 2 3 29 May; 8, 14 June !/2 and logging was active at distancesfrom 5 to 3 1 20 July 1/0 20 kin. !977(5years) ! 2 30 May; 4 June !/1 We were interestedin assessing(1) the extent 2 3 2, 3, 12 June 2/! to which primary-forestbirds used the planta- 3 2 22 July 1/ 1 tion, (2) how the bird community in the plan- 4 4 24, 30 July 2/2 tation developed through time, and (3) ecolog- !979(3years) ! 6 3, !3 June;17, 3/3 ical factors that played a role in this 29 July 2 4 7 June;18 July 2/2 development. To this end, we censusedbirds !981 (! year) ! 5 6, !1 June;23 July 3/2 in different age groups of one speciesof plan- 2 3 6, 9, 1! June 1/2 tation tree, Albizia falcataria.We selected this All surveys 44 28 May-30 July 23/21 speciesbecause preliminary observations(e.g. "Early (0600-0900)/late(0930-1230). A. G. Davies unpubl. manuscript) indicated that Albiziagroves were more attractiveto birds than were those of other plantation trees. conducted in Asia. Others include Davies (un- Locally called "Batai," Albiziafalcataria is na- publ.manuscript), Davies and Payne(1982), Duff tive to the Molucca Islands, New Guinea, New et al. (1984), and Stuebing and Gasis (1989), Britain, and the Solomon Islands, but has been which were surveysmainly of mammalsin Sa- introduced to most parts of Malaysia (Cockburn bah Softwoods, and Wilson and Johns (1982), 1976).Synonyms are A. falcataand A. moluccana; which examined a restricted set of mammal and sometimesthe speciesis placed in the genus bird speciesin a similar plantation in east Ka- Serianthes(Mabberley 1987).Albizia is a popular limantan (Indonesian Borneo). These investi- plantation tree becauseit grows fast,gaining as gations complement data collected in recent much as 6 m in height and over 12.5 cm in girth years on the effectsof logging on Malayan and per year in its first few years.It is alsoa legume Bornean bird and mammal communities (e.g. that improves soil quality (Cockburn 1976, K.- Wilson and Wilson 1975, Johns 1983,1986,1989, C. Tan pers. comm.). Wong 1985,Lambert 1992). Beehler et al. (1987) also surveyed birds in several plantation and METHODS man-disturbed forest habitats in the Eastern Ghats of India. However, the age and config- Data were collectedin each of the following five habitatsor "plot types":one-, three-, five-, and seven- uration of the forestsand plantations they stud- year-old Albizia,and primary forest (summarizedin ied (including coffeeand teak groves)differed Table !). To comparerichness and diversity, we com- from the newer exotic-treeschemes of Malaysia piled accuratelists of the kinds and numbersof birds and Indonesia. present in each plot type and converted these into Sabah Softwoods is located in the Kalabakan frequency values. For each plot type we surveyed Forest Reserve in southeastern Sabah (4ø37'N, replicate "plots." To ensure consistencyamong plots, 117ø45'E,altitude < 300 m). The plantation was we selected areas with similar altitudes, terrains, and begun as a joint venture by the SabahFoun- distancesfrom streamsand primary and loggedforest. dation and North Borneo Timber Company in In each plot, a quadrat trail of 300 m on a side was cut; one of the four sides consisted of an access road. 1972. Prior to development, most of the region To census,we walked the trails,allowing 3 h for each had been covered with primary forest, domi- quadrat.Surveys were conductedat two differenttimes nated by trees of the family Dipterocarpaceae of day: 0600 to 0900 and 0930 to 1230 standardtime. (Wood and Meijer 1964, Whitmore 1984). This We consideredall surveys of a given plot to be rep- forest was heavily logged in the early and mid- licates,but endeavoredto complete equal numbers of 1970s, and a large area was clear-felled and early- and late-morningsurveys for eachplot and plot burned to establish the plantation. At the time type. Every bird that was seen or heard was noted. July 1993] BorneanPlantation Birds 531 TABLE2. Feeding-guild classificationwith examples. 1 Raptors (r): Hawks and owls. 2 Terrestrial insectivores (ti): Pittas, some babblers, and thrushes. 3 Bark-gleaninginsectivores (bgi): Woodpeckers,nuthatches, and somebabblers. 4 Foliage-gleaninginsectivores (fgi): Many babblersand warblers. 5 Sallying substrate-gleaninginsectivores (ssgi): Trogons, some kingfishers, broadbills, and drongos. 6 Sallying insectivores(sai): Flycatchers. 7 Nectarivores (n): Sunbirds, spiderhunters, Loriculusgalgulus, and Dicaeumtrigonostigma. 8 Arborealfrugivores (af): Most pigeons,most barbets, Calyptomena, Irena, crows, mynas, and mostbulbuls. 9 Arboreal frugivores/faunivores(aft): Hornbills and Megalaimachrysopogon. 10 Terrestrial