J. Field Ornithol., 70(1):58-70 AVIAN DISTRIBUTION IN DOMINICAN SHADE COFFEE PLANTATIONS: AREA AND HABITAT RELATIONSHIPS JOSEPHM. WUNDERLE,JR. InternationalInstitute of TropicalForestry USDA b orest Service P. O. Box 490 Palm• Puerto Rico 00721 USA Abstract.--Residentsand wintering Nearctic migrantswere sampledby point countsin 40 smallto medium-sized(0.07-8.65 ha) shadecoffee plantations with an overstoryof Inga vera in the CordilleraCentral, DominicanRepublic. The purposeof the studywas to determine the relative importance of plantation area, isolation, and habitat structure to avian distribu- tion and abundance.Variation in abundancewas unrelated to plantation area for all migrant species(n = 7), whereasthe local abundanceof four of ten resident speciesincreased significantlywith area. Elevationwas the only variablethat significantlycontributed to the total number of speciesper plantation (fewer speciesat higher elevation), and no habitat variablessignificantly contributed to variation in the total number of migrant species.In contrast,significantly higher numbers of resident specieswere found in larger and older plantationsat lower elevations,characterized by numerous stems-•3 cm DBH, little or no pruning of overstorybranches, and maximum canopycover at 12.0-15.0 m. Coffee planta- tions with high levelsof structural and floristic diversityshould be encouragedfor avian conservation,and even the smallestplantations, if not too isolated by treelessareas, can contribute to avian abundanceand diversityin tropical agricultural regions. DISTRIBUCION DE AVES EN ALGUNAS PEANTACIONE$ DE CAF• DE $OMBRA EN LA REPI•BLICA DOMINICANA: RELACIONE$ ENTRE • Y HABITAT Sinopsis.--Enla Cordillera Central de la Reptblica Dominicana,se muestrearon(por conteo de puntos)40 plantacionesde caf• de sombra(cuyo tamafio vari6 de 0.07-8.65 ha) con un docel de Inga vera.E1 proptsito del estudiofu• determinar la importanciarelativa del •rea de la plantacitn, el aislamiento de la misma y la estructura del habitat, en relacitn a la distribucitn y abundanciade aves.La variacitn en abundanciano estuvorelacionada al frea de la plantacitn para las especiesmigratorias estudiadas (n = 7), aunque la abundancia,de cuatro de un total de diez especiesresidentes, aument6 significativamentecon el incremento en frea. La elevacitn fue la 6nica variableque contribuy6significativamente al ntmero total de especiespor plantacitn (a mayor elevacitn menos especies),y ninguna variable en el habitat contribuy6 significativamentea la variacitn en el ntmero total de especiesmigrato- rias. En contraste,un ntmero significativamentemayor de especiesresidentes fue encontra- do en plantacionesde mayor tamafioy de mflstiempo, establecidasa elevacionesmfls bajas. Estasse caracterizaronpor tener tallos > a 3 cm DBH, un sotobosquepoco alterado y un docel mSximo de 12.0-15.0 m. Deben promoverseplantaciones de caf• con altos nivelesde diversidad(tanto estructuralcomo floristico) para la conservacitnde las aves.Inclusive las plantacionesmfls pequefias,si no estan muy aisladasde otras fireascon firboles,pueden contribuir a la abundanciay diversidadde avesen las regionesagricolas del trtpico. Traditiorial coffee plantationsthat include an overstoryof shadetrees have a relativelyrich avifauna (e.g., Wetmore 1916; Griscom1932; Augilar- Ortiz 1982; Wunderle and Latta 1996; Greenberg et al. 1997a,b). The relativelyhigh diversityof birds found in shade coffee plantationsand the presencethere of some forest-dwellingspecialists suggest that shade coffee may provide a valuable refugia for birds and other organismsin heavily deforested agricultural regions of the tropics (Perfecto et al. 58 Vol.70, No. 1 Birdsin CoffeePlantations [59 1996). However, not all shade coffee plantations may be equivalent in their attractivenessto birds, as variation in canopy structure and compo- sition influence avian abundance and diversity in some plantations (Greenberget al. 1997a;Calvo and Blake 1998;Johnson, in press).Dem- onstrationof the potential value of shade coffee to birds requires iden- tificationof particularhabitat characteristics of the plantationswith which variousbird speciesare associated. Plantation area should influence avian distribution in shade coffee plantations,based on other studiesof species-areaeffects on birds (re- viewedin Burgessand Sharpe1981; Williamson 1981; Harris 1984). None- theless,species differ considerablyin their responseto patch size. For instance,many Nearctic migrantsavoid small isolatedforest patcheson the breeding grounds (e.g., Lynch and Whigham 1984; Robbinset al. 1989), although they may readily inhabit similar or even smaller-sized patcheson the tropicalwintering grounds (Robbins et al. 1987; Green- berg 1992). Although most species-areastudies have been conductedin the temperateregion, the few tropical studiesindicate that many tropical residentspecies are sensitiveto habitatpatch size (e.g., Willis 1974, 1979; Lovejoyet al. 1986). Thus, smallisolated shade coffee plantations should support fewer speciesper unit area of habitat. In the Dominican Republic shade coffee plantations often constitute the only broadleaftree coverremaining in mid-elevationagricultural ar- eas.There plantationsof different sizesare typicallyisolated by pastures or croplandfrom other plantationsor forestpatches of pine or mixed pine and broadleafspecies. A varietyof residentand migrant bird species occupythese plantations,thereby maintainingavian diversityin an oth- erwise inhospitableagricultural landscape (Wunderle and Latta 1996). However,the relativeimportance of plantationarea, isolation, and habitat structurefor attractingdifferent speciesis unknown.The objectiveof this studywas to examinethe relativeimportance of thesevariables on species- area relationshipsin shade coffee plantations.A multivariateapproach wasused to identify the plantation characteristicsassociated with individ- ual migrant and resident species. METHODS Studysite.--Forty shade coffee plantations(mean = 1.1 ha, range 0.1- 8.7 ha) were sampledin the vicinityof Constanza(18ø54'N, 70ø37'W), Ebano Verde (19ø2'N, 70ø34'W), Manabao (19ø6'N, 70ø48'W) and Jara- bacoa (19ø9'N, 70ø39'W),La Vega province,at an elevationof 480-1240 m in the Cordillera Central of the Dominican Republic. The plantations are located in a zone that receivesan annual rainfall of approximately 1200 mm (Hartshorn et al. 1981) and is classifiedas subtropicalmoist forestin the Holdridge life zone system(Anonymous 1967). In this re- gion, coffee is cultivatedin areasthat were originallypine forest (Pinus occidentalis).Pine forests,most of which have been logged selectively,re- main in scatteredpatches on the steeperslopes. These relict standscon- 60] J.M. Wunderle,Jr. j. FieldOrnithol. Winter 1999 tain variableamounts of broadleafunderstory that hasbeen degradedby fire, cutting, or grazing. Broadleafcanopy trees are restrictedprimarily to shadecoffee plantations,fruit and ornamental trees along fence rows and around homes, and in arroyos lined primarily with the exotic Syzygiumjambos.Broadleaf forest or woodlandare absentand pastureand cultivatedground cropsare the predominant cover type. Bird censuses.--Birdpopulations were sampled 6-19 Feb. 1992 using fixed-radiuspoint counts (Hutto et al. 1986). An observerrecorded all birds seen or heard during a 10-min period at each point. Pointswere placed in the center of the smallestplantations. In larger plantations, each point wasset at least 100 m from each other and equidistantfrom the plantation edge, at least 20 m from the edge. Each point was 100 m or more from all others. Only in the ten largestshade coffee plantations was it possibleto conduct more than one point count. Countswere ini- tiated at sunrise and terminated before 1100 h, with most counts com- pleted before 1030 h. During the count, the observerestimated the min- imum distanceto each bird detectedwithin a 25-m radius.Analyses were restricted to counts of birds detected only within a 15-m radius circle ensuringthat all plots, including those in the smallestplantations, con- tained equivalentamounts of coffee habitat. The surveysexcluded swal- lows,swifts, and raptors. Habitat measurements.mVegetationwas measured in 16-m diameter plots (0.02 ha) centered at each point. Stemsof all standingtrees and saplings->3 cm were measured 1.3 m above the base (DBH) and identi- fied to species.Stem density of coffee plantsat breastheight wasestimated along four 8-m transectsrunning in the cardinal directionscentered with- in the 0.02-hacircle. Shrub densitywas determined by an observerwalk- ing along the transectand counting all woodystems (<3 cm) touching the observer'sbody and outstretchedarms at breastheight. The contri- bution of coffee and other plant specieswas recorded separately. Foliage-heightprofiles were determined at 20 points located at 1.6-m intervalsalong the north, south,east, and westradii of each circularplot (Schemskeand Brokaw 1981). A 3-m pole (2.0-cm diameter) marked at 0.5-m intervalswas placed verticallyat each sample point. The presence or absenceof foliage touching the pole within each height classwas re- corded aswell as the identity of the foliage.For height intervalsabove 3 m, we sightedalong the pole and recorded the presence/absenceof fo- liage in each of the following height intervals:3-4, 4-6, 6-8, 8-10, 10- 12, 12-15, 15-20, and 20-25 m. Total foliage per height interval wascal- culated by summing the number of points (maximum = 20) with the presenceof foliage at a particular height interval. Foliage densitywas calculatedby