THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC.

VOL. 23 SUMMER 1989 NO. 2

J. RaptorRes. 23(2):27-38 ¸ 1989 The Raptor ResearchFoundation, Inc.

NEOTROPICAL RAPTORS AND DEFORESTATION: NOTES ON DIURNAL RAPTORS AT FINCA EL FARO, QUETZALTENANGO,

J^¾ P. VANNINI

ABSTRACT.--Twenty-onespecies of diurnal raptors (Family Cathartidae, Pandionidae,Acciptridae and Falconidae)are reportedfrom Finca El Faro, Quetzaltenango,Guatemala. Observationswere made from 1 March 1987 through 5 March 1989. Data are alsoincluded for an additionaleleven of diurnal raptorswhose presence is suspected.Comparisons with known diurnal raptor componentsof 4 well-studied Central American parks and reservesare presented.

Our currentknowledge of ecologicalrequirements total avifauna. This percentagerelationship is the of tropical raptors is poor (Newton 1979; Thiollay highest for a political region in the northern and 1985a). A recentsummary of data availableon trop- middle Neotropics(this study).Guatemala's diurnal ical forestraptors suggestsa dearth of basicnatural raptorsinclude 6 migrant taxa which spendvarying history data for most species(Thiollay 1985a). periodsof time in the Nearctic region; 35 resident In particular studies on diurnal raptors of the speciesand 8 specieswith migrant and residentpop- Neotropicsare lacking. A review of recentliterature ulations (Land 1970; Vannini, unpubl. ms.). (e.g., Burton 1983) suggeststhat older references Finca El Faro is a privately owned plantation on continueto be cannibalized(Dickey and van Rossem Guatemala's Pacific vetsant (Fig. 1), owned and 1938; Blake 1953; Slud 1964; Wetmore 1965; Smithe managedby AgroindustriasTamer, S.A. The plan- 1966; Brown and Amadon 1968; Monroe 1968; Land tation has been the focusof a joint researchproject 1970; Meyer de Schauensee1970; Alvarez del Toro since 1 March 1987 between the Fundaci6n Inter- 1971). While recentpublications on the region'savi- americanade Investigaci6nTropical (FLIT) and the fauna have addedminor ecologicalnotes and distri- University of Texas at Arlington (UTA). During butional data (Ridgely 1976; Blake 1977; Parker et the course of floral and faunal inventories a number al. 1982; Hilty and Brown 1986), few comprehensive of observationswere made on the diurnal raptorsof studieshave been made. Notable exceptionsdeal this reserve. with reproductivebiology of more spectacularspecies This paper summarizesthe data collectedduring (Harrison and Kiff 1977; Rettig 1978; Bierregaard the course of these inventoriesand comparesthe 1984; Lyon and Kuhnigk 1985; Jenny and Cade known diurnal raptor fauna of Finca E1 Faro with 1986). While publicationsdealing with diurnal rap- other well-studiedparks and reservesin the northern tors of the Indo-australian region have provided us Neotropicsin an attempt to demonstratethat plan- with insight into the habits of thesebirds (Hollands tation areas are utilized by a wide range of native 1984; Coates 1985), raptors of the Neotropicsre- and migrant raptors, and may provide valuable main largely neglected. "buffer" areas when adjacentto native forest. Guatemala'savifauna is amongthe better studied STUDY SITE AND METHODS in Central America (Salvin and Godman 1897-1904; Griscom 1932; Smithe 1966; Land 1970; Vannini, Finca E1 Faro is a 670 ha subtropicalplantation located on the south-westernslopes of VolcanesSanta Maria and unpubl. ms.). The known avifaunal componentto- Santiaguito,in the departmentof Quetzaltenango,Gua- tals 714 species(Vannini, unpubl. ms.). Diurnal temala. Elevationswithin the farm range from ca. 800- raptorscomprise 49 speciesor 6.86% of the country's 2500 m. Mean annual precipitation at 875 m elevationis

27 28 JAY P V^NNINI VOL. 23, NO. 2

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"G EO -- TECNICA# Figure 1. Hypsometricmap of Guatemalaand showing the locationof FincaE1 Faro (Star)in southwestern Guatemala. ca. 4500 mm with peaksfrom late May-September (IN- analysis shows ca. 220 ha-under coffee (Coffea arabica), SIVUMEH 1969). The site has been under continuous ca. 80 ha under cardamom (Elettaria cardarnornurn),ca. 40 cultivation sincethe early 1930s and has been subjected ha under macadamia(Macadamia integrifolia) cultivation to severaldevastating periods of volcanicactivity sincethe and ca. 330 ha as wildlife refuge area. 1902 eruption of Volcan Santa Maria (McBryde 1945). Conditionswithin the cultivatedareas range from high The most dramatic of these nuke eruptionsoccurred in density coffee plantings under heavily pruned Inga sp. November 1929 and 19 April 1973 (Rose, unpubl. ms.). shadethrough "climax plantation" cardamomunder forest Presently,the site is being managedas a diversified canopywith a considerableamount of nativeundergrowth. plantation and premontane researchfacility. Land use The area is rich in hydrologicalresources. Largest streams SUMMER 1989 NEOTROPICALRAPTORS 29

on the farm are Rios Nima' 1 and 2 which originate on not as commonas Coragyps,during October-Novem- the property above2000 m elevation. ber when migrants are present, Turkey Vultures Vegetationin the wildlife refuge area datesprimarily may be observedin considerablenumbers above 1100 from April 1973 and is extremelydynamic. Although there are few treeswhich exceed50 cm dbh, natural regeneration m elevation.Both adult andjuvenile have been hasbeen rapid. Conditionswithin this successionaryforest recorded. are comparableto thoseencountered in many mature pre- montaneforests elsewhere along Guatemala'sPacific ver- Black Vulture (Coragypsatratus) sant excepttank bromeliadsand orchidsare rare (pers. obs.). Black Vultures are the most commonlyobserved Data for this studywere collectedon weekendsbetween diurnal raptor at Faro during all periods except 0500 and 1900 H from March 1987 throughMarch 1989. October-November. Although observedat all ele- Road Surveys(adapted from Fuller andMosher 1987). The farm has ca. 15 km of well-ballasted access roads at vations within the farm, Black Vultures are most elevations from 800-1480 m on the east reserve entrance common at elevations below 1450 m. Due to limited to ca. 1650 m on the west reserve entrance. Observations refuse availability, this specieshas not become a were made from various four wheel drive vehicles in the problemscavenger as at other parks and reservesin companyof other observers.Vehicles were stoppedonly when raptors were observedand no standardspeed was Central America (Burnham et al. 1988; pers. obs.) employedduring the courseof the study. Foot Surveys(adapted from Fuller and Mosher 1987). Osprey (Pandionhaliaetus) In addition to use of vehicleaccess roads for foot surveys, the wildlife refugearea has7.5 kmsof steppedtrails, 2 m A singlejuvenile Ospreywas observedon 14 Feb- wide which were used for surveys.Elevations on the trail ruary 1988 at 875 m elevationflying eastwardca. rangefrom 1480-2200 m (range= 720 m). Althoughsteep 10 m overhead.No other observationsof this species in sections,visibility from the trail is generally excellent. havebeen made and Ospreyare obviouslyrare tran- Artificial light gaps have been cut in order to increase sients at Faro. Several coastal avian speciesfre- visibilityand to createedge within the forest.Observations were made while walking the trail or standingat light quently are observedat higher elevationsalong the gapsin the companyof otherobservers. No standardspeed volcanicchain (Land 1970; pers. obs.). was employedduring the courseof the study. Mist Nets (adapted from Karr 1979). Three primary Cooper's Hawk (Accipitercooperi) mist net stations have been established for avian and chi- ropteraninventories, located at 875 m (plantation);1100 Cooper's Hawks have been observedon 4 occa- m (plantation/riparian forest)and 1450 m (premontane sionsat Faro at elevationsranging from 1100-1600 forestedge). Nets are generallyused in pairs and range m. On 14 November 1987 a juvenile was observed from 5-19 m in length and have 3-4 trammels.Nets are set at heightsvarying from ground level to 8 m and are in companywith a mixed flock of migrating and supervisedby a minimum of 2 observers.Although mist residentraptors. On 12 March 1988 an adult female nets resultedin only 2 diurnal raptor capturesfrom Jan- was observedsoaring over gallery forest at 1100 m. uary-June 1988, the presenceof vocalizingbirds in mist On 8 May 1988 a poorlymoulted adult wasobserved netsor in hand attractedraptors to within closerange on soaringover an area with newly planted coffeeand many occasions. Observationswere made using Bushnell 10 x 40 bin- on 13 November 1988 an adult was observedsoaring oculars,Swift 10 x 44 binoculars,Jason 7 x 50 binoculars over premontaneforest edge. Cooper's Hawks are and a Celestron100-200 x spottingscope anchored on any rare migrants in Guatemala, and observationsdur- convenientperch. Photographic records of individualdiur- ing this studyrepresent the first confirmationsof this nal raptorsand intraspecific/interspecificinteraction were made whenever feasible with Canon A1 and AE1 35mm species'presence in the westernhighlands. cameraswith lensesranging from 28-500 mm. Identification proceduresat Finca El Faro require: Sharp-shinnedHawk (A. striatus) voucherspecimens in the caseof plants and lower verte- brates;unmistakable photographic identification or mul- A migrant species. Sharp-shinned Hawks are tiple confirmationsby reliable fieldworkersfamiliar with commonly observedat Faro at elevationsranging the taxon in questionfor birdsand mediumto large mam- from 1100-1600 m from January-April. Two adult mals (see Acknowledgments). femaleswere mist-nettedduring March 1988. Pur-

SPECIES ACCOUNTS suit and capture of Swainson'sThrush (Catharus ustulatus)has been observed,and collectedprey re- Turkey Vulture (Cathartesaura) mains have included doves(Leptotila sp.). During Turkey Vulturesare common throughout the year periodsof heavyInga sp. and Cecropiasp. flowering at all elevationswithin the farm. Althoughgenerally in February, up to 3 adult Sharp-shinnedHawks 30 Jay P. VANNINI VOL. 23, NO. 2 havebeen observed aggressively defending small ter- Roadside Hawk (B. magnirostris) ritories (<3 ha) containinghigh densitiesof native Surprisingly, RoadsideHawks are uncommonon and migrant passetines. Faro. Although year-round residentsand breeding birds occurin the area, encountersare infrequent. Zone-tailed Hawk ( albonotatus) Juvenile and adult birds have been observedat el- Zone-tailed Hawks are frequently observed evations ranging from 875-1100 m. I hypothesize throughoutthe year at Faro from ca. 900-1200 m that diversity of habitats on Faro, in addition to elevation.At least 1 adult pair is residentin the area competitionfrom other small raptors,does not favor and single adults are observeddaily during the dry high Roadside Hawk populations. In sugarcane season(January-May). An adult was observedto (Saccharumofficinalum) fields within 15 km airline maintain a foraging territory during February- of Faro the speciesutilizes power poles as perches March 1988. Prey were primarily Basilisks(Basi- and is presentat high densitieswhere there is little liscusvittatus) and Ameivas(Ameiva undulata). Cap- or no competitionfrom other similar-sized diurnal tures were effectedby soaringover recentlyplanted raptors (per. obs.). coffeeand stoopingfrom an altitudeof 50 m. Success rate during brief observationsappeared to be ca. 25% Grey Hawk (B. nitidus) and observationsduring this studyrepresent the first Grey Hawks are abundant raptors at Faro at confirmationof this species'presence in the western elevationsranging from ca. 800-1500 m. Several highlands. adult pairs are conspicuousthroughout the year. Soaring aggregationsof up to 4 birds have been Short-tailed Hawk (B. brachyurus) observedand aggressiveinteractions between indi- This small hawk is commonthroughout the year viduals over territories are frequent. Grey Hawks at elevationsranging from ca. 800-1700 m. At least are adaptablebirds with catholicdiets and may use 2 pair, and possiblya third, are believedto nest in severaltechniques to captureprey. In mostcases the the area. Three colormorphs; white-chested, grey- simply drops from a perch onto small verte- chestedand uniformly dark birds were observed. brates such as and .During March Courtship flights occurred from February-April 1988 severalunsuccessful attempts by an adult to 1988. Three Short-tailed Hawks were observed capture feeding Green Parakeets (Aratinga holo- soaring at ca. 1500 m elevationson different dates chlora)were observed.Prey capturetechnique was in May 1988 and may have representeda breeding strongly reminiscentof that used by Accipiterspp. pair with the fledgling(s).An immature bird was and were madeby glidingat high speedunder plan- observedperched and eating a at 1550 m on tation canopy.Most often observedin open habitats 5 March 1989. Reported observationsrepresent the on Faro, 1 pair is most regularly observedperched first confirmationof this specieson Guatemala'sPa- and hunting in mature, enclosedplantation. cific versant. Broad-winged Hawk (B. platypterus) Red-tailed Hawk (B. jarnaicensis) A singleadult Broad-wingedHawk was observed Red-tailed Hawks are infrequently observed on Faro at 875 m elevation17 January 1988. The throughoutthe year on Faro at elevationsranging bird soaredbriefly overcoffee plantation and moved from ca. 1100-2200 m. During January 1988 a pair slowlyeast. Commonly observed in the westernhigh- was observeddisplaying over grasslandsand pine lands (Land 1970; pers. obs.), this migrant species forestsof upper Volcan Santa Maria. No juveniles may be more commonat upper elevationsthan this havebeen observed. Red-tailed Hawks are normally single record would suggest. restrictedto open areason Faro and appear to reach lower elevationsvia the Santiaguito/Rio Nima 2 Swainsoh's Hawk (B. swainsoni) corridor,thus avoidingthe belt of premontaneforest A migrant species.Small aggregationsof Swain- between 1500-2200 m. However, on 18 February son'sHawks are frequentlyobserved during migra- 1989 a uniformly dark Red-tailed Hawk was ob- tion (September-Octoberand April-May). Individ- served soaring over premontane forest canopy at uals are uncommonlyobserved September-May. On 1750 m. several occasions in October-November 1987 1 noted SUMMER 1989 NEOTROPICAL RAPTORS 31 singlebirds gliding eastward along the volcanicchain confirmation of this speciesfor the western high- at approximatelythe elevationof the coneof Volcan lands. Santa Maria (3772 m). Several birds were observed to drop rapidly to an altitude of 1200-1500 m in Tyrant Hawk-Eagle (S. tyrannus) order to group with other Swainson'sHawks and Tyrant Hawk-Eagles are commonlyobserved on migrating Turkey Vultures. Faro betweenca. 800-3000 m. Aerial displayflights by a resident pair were observedduring March- Solitary Eagle (Harpyhaliaetussolitarius) April 1988. A complex courtshipdisplay flight in- On 2 occasionsduring January-February 1988, volving contactand roll-overs was observedin the I briefly observedwhat I am certain were adult company of Peregrine Fund biologistson 18 Feb- Solitary Eaglessoaring at elevationsfrom ca. 1000- ruary 1989 at ca. 2200 m. The pair is believed to 1100 m. Subsequentobservations by a field associate nest on the reserve'slowest edge at 1400 m or just familiar with Solitary Eagles elsewhereconfirmed east of Faro. From February-June 1988, the adult the presenceof at least1 adult bird on Faro. A single male was observedsoaring daily from 0900-1100 observationon 23 June 1988 of a juvenile bird at H. Vocalizations were made constantly while soar- ca. 1500 m elevationwas made by a group of biol- ing and couldbe heard for severalkms on clear days. ogistsfrom the University of Texas at Arlington. On 27 February 1988 a juvenile female made a very Likely, a pair of these eaglesbreeds on the upper close approach (<8 m ) while I was removing a forestedslopes of Volcan Santa Maria or Volcan protesting Grey-cheekedThrush (Catharusmini- Zunil immediately to the east. Observationsduring mus) from a mist net in riparian forest at 1100 m this study represent the first confirmation of this elevation. The bird appeared from down a gorge, specieson Guatemala'sPacific versant. adjacent to a cardamom plantation and remained perchedin a Cecropiasp. for ca. 15 min. The hawk- eagle appeared extremely interested in the thrush White Hawk (Leucopterr•isalbicollis) vocalizations,raising the crestand craningto obtain A singleWhite Hawk was observedsoaring over a better view when the thrush struggledin my hand, the runway on Faro at 850 m elevationon 15 March yet remarkably unconcernedover the excitedcon- 1987. Although conspicuousat a distancewhen sit- versation I was having with a field assistant.A ju- ting along forestedge, White Hawks may occurin venile Tyrant Hawk-Eagle, possiblythe same in- mature plantation or forest without being observed dividual, has since been observed close to the house for some time. Comments by agricultural laborers at 875 m on several occasions from March-Decem- on the neighboringLa Florida plantation lead me ber 1988. Although no observationsof hunting be- to believethat investigationthere would reveal a pair haviour have been witnessed, Crested Guans (Pe- of these birds. nelope purpurescens)and Magpie-Jays (Calocitta formosa)have been observedto give alarm when a Ornate Hawk-Eagle (Spizaetusorrzatus) Tyrant Hawk-Eagle passesoverhead. Observations A large adult female Ornate Hawk-Eagle was reportedin this studyrepresent the first confirmation of this species'presence in the western highlands. observedat closerange on 19 July 1987. The bird was perched15 m from the ground in a large Ce- cropia sp. at 1480 m elevation, exactly along the Falcon (Falco rufigularis) wildlife refuge area boundary.The bird calledcon- Individual female Bat Falcons have been observed stantlyfor 5 min with crestraised, then soaredslowly on severaloccasions at 875 m elevation. On 17 June downhill over newly-planted coffee.Two additional 1988, severalbiologists from the University of Texas observationswere made in 1987; 1 of a much smaller at Arlington observeda bird at closerange near the bird flying over gallery forest and plantation along house.The Bat Falcon resultedin omnipresentflocks Faro's eastern border at ca. 1300 m elevation. No of Vaux's Swifts (Chaetura vauxi) and White-col- observationswere made in 1988 or early 1989. I lared Swifts (Streptoprocnezonaris) "skying up," al- suspectthat the birds breed further east on Volcan though no chaseswere observed.An adult female Santa Maria and visit Faro occasionally.Observa- was observedhunting Vaux's Swiftsduring January tions recordedduring this study representthe first 1989 by a field associate.Interestingly, several cap- 32 J^Y P. VANNINI VOL. 23, NO. 2 tive Bat Falcons are housedin a breeding chamber just belowwhere the bird was perched.On 4 March nearby.Although no interactionwas witnessed,the 1989 at 1830 H an adult femalewas observedto fly presenceof a vocalbreeding pair may attract wild over a river canyon at 1650 m and perch for ca. 15 individuals.Bat Falconsare extremelyrare on Gua- min under canopy. The observationsduring the temala's Pacific versant. Indiscriminate use of or- courseof this studyrepresent elevational records for ganochlorinepesticides may be affectingpopulations the speciesin Guatemala. in certain areas(Cade 1982). Captive-bredBat Fal- conswill be releasedat Faro during 1989. Crested Caracara (Polyborusplanca) Caracaras are irregular transients at Faro American Kestrel (F. sparverius) throughoutthe year. Individuals have beenobserved A migrant species;presence of residentsubspecies at elevationsfrom ca. 800-900 m, and occasionally suspected.Kestrels were frequently observedfrom an individual may take up residencefor severaldays October 1987 through April 1988 and appear to near the plantation houseat 875 m. Caracaras fre- establish winter territories. At least 1 adult male was quently harasscaptive in the breedingproj- observedon 25 June 1988, suggestingthat it may ect, and the speciesis very commonat lower ele- also be presentas a resident.Kestrels favor newly vations within 10 km airline of Faro. plantedcoffee plantations and areasadjacent to San- SPECIES WHICH POSSIBLY OCCUR AT FINCA EL FARO tiaguito at elevationsfrom ca. 1100-1500 m but have not beenseen in mature plantationsor in the wildlife King Vulture (Sarcoramphuspapa) refuge area. As newer plantings mature, kestrels Probable.King Vultures are rare or uncommonly may ultimately be restrictedto Rio Nima 2 drainage observed on Guatemala's Pacific versant due to ex- on Faro. tensive deforestationand improved livestockman- agement(Dickerman, unpubl. ms.; pers. obs.). Oc- Laughing Falcon (Herpetotherescachinnans) casionallystill observednear Siquinalfi, Escuintla, A single Laughing Falcon was briefly observed the bird is probablya rare transientin westernGua- on 14 November1987 in an aggregationof soaring temala. migrant and native raptors at ca. 1300 m elevation. An individual was observed30 June 1988 perched Bicolored Hawk (Accipiterbicolor) in a dead tree near the plantation houseat 875 m. Probable. Bicolored Hawks are known from iso- Absenceof a breedingpopulation is surprising.Con- lated locationson the Pacific versant(Griscom 1932) ditionson Faro favorLaughing Falcons, and common and range to elevationsof 1350 m in Guatemala prey itemssuch as medium-sizedlizards and snakes (Land 1970). A crypticbird which doesnot vocalize are abundant (Campbell and Vannini 1988). Pres- frequently, accousticalluring or deep forestmist net ently, the LaughingFalcon is considereda transient at E1 Faro. stationsmay be required to confirm presence.On 5 March 1989 1 briefly observeda medium-sized,white Collared Forest-Falcon (Micrastursemitorquatus) breastedAccipiter sp. at 1550 and 1700 m elevation. Suspectedpresence of a resident Sharp-shinned A resident Collared Forest-Falcon was heard call- Hawk (A. striatuschionogaster) which is similar to ing from March-May 1987 and during April 1988 pale morph BicoloredHawks made a positiveiden- at ca. 1600 m in early evening.Although the bird tification difficult. respondsto imitationsof its call, this individual has not beenseen. Prey remainsfound within 100 m of Common Black Hawk (Buteogallusanthracinus) Its preferredperch include White-faced Quail-Dove Known from similar elevations and habitat within (Geotrygonalbifacies) and Ruddy Quail-Dove (Geo- trygonmontana). Size of the dovesand frequencyof 15 km airline (Griscom 1932). Now rare on Gua- remains found at this perchsuggest kills by the for- temala's Pacific piedmont. est-falcon. A Collared Forest-Falcon was flushed in a mature macadamiaorchard on 10 April 1988 at Marsh Hawk (Circuscyaneus) ca. 1000 m elevation. A large flock of Red-billed Probable. Marsh Hawks are known from within Pigeons(Columba flavirostris) flushed seconds later, 10 km airline at Quetzaltenango(Griscom 1932). SUMMER 1989 NEOTROPICALRAPTORS 33

Presenceas a migrant at elevations >2200 m in (Land 1970; J.P. Jenny, pers. comm.; pers. obs.). grasslandalmost certain. Peregrinesare infrequently seen in thewestern high- lands,perhaps due to the presenceof few observers. White-tailed (Elanus caeruleus) The Nima 2 river valley and Santiaguito'sslopes Known from similar elevations and habitat within provide suitable habitat and abundant quarry for 15 km airline (Vannini, unpubl. ms.) and rapidly migrant individuals. expandingits range in northern Central America. INTERSPECIFIC INTERACTION OBSERVED IN Black Crane Hawk (Geranospizanigra) DIURNAL RAPTORS AT FINCA EL FARO Rare or uncommon on Guatemala's Pacific ver- 1) Cathartesaura: mixed flocksof C. aura, Coragyps sant and known from very few localitiesat upper atratusand occasionallyPolyborus planca have elevationsalong the piedmont(Griscom 1932; Land been observed.On 14 November 1987, an ag- 1970). gregationof C. aura, C. atratus,Accipiter cooperi Double-toothed Kite (Harpagusbidentatus) (1), Buteonitidus (1), B. swainsoniand Herpeto- therescachinnans (1) was observed at ca. 1300 Probable.The specieshas only recentlybeen con- firmed as a resident of Guatemala's Pacific versant m elevation at 0600 H. No aggressionwas not- ed. (pers.obs. with photo).An adult Harpaguswas re- 2) Coragypsatratus: see C. aura. portedlyobserved at closerange on Faro in mature 3) Accipitercooperi: see C. aura. plantation during June 1987 (J. Darling, pers. 4) Accipiterstriatus: on 6 March 1988 an adult A. comm.)but presenceremains unconfirmed. striatuswas observedto fly out of riparian forest Grey-headed Kite (Leptodoncayanensis) at 1100 m elevation and harass a soaring ju- venile Spizaetustyrannus. Three initial stoops A lowlandspecies in muchof Guatemala.Known were made without contact.A fourth stoopre- from 2 localities in the area; Finca El Carmen, 25 sultedin a visible strike to the eagle'sdotsum. km airline from Faro (pers. obs.)and Mazatenango The hawk-eagle commenced vocalizing and (P. Rockstroh,pers. comm. with specimendeposited rolled to repel a fifth stoopbefore rapidly mov- at National Museum of Natural History). Both rec- ing out of the area. Intraspecificaggression be- ordsare from mature plantationat somewhatlower elevations. tween similar sized A. striatus was commonly observedin February-March 1988. Merlin (Falco columbarius) 5) Buteoalbonotatus: on 14 February 1988 an adult Knownfrom very few records in Guatemala(Land B. albonotatusand an adult B. jamaicensiswere 1970) but recorded at low and middle elevations observedsoaring at similar altitudesat 1100 m elevation at 0930 H. After ca. 15 rain of obser- along the Pacific versantas a migrant. vation the B. albonotatuswas observedto stoop Orange-breastedFalcon (F. deiroleucas) the B. jamaicensis,which rolled and vocalized. A remotepossibility. A singlespecimen known The B. jamaicensismoved off upslopeand dis- from the Pacific versant of Guatemala is from Finca appeared from view while the B. albonotatus E1 Cipr•s, a plantationon the southernslope of continuedto forage. Volcan Zunil, 15 km airline from Faro at 600 m 6) Buteo brachyurus:commonly observed soaring elevation(Griscom 1932). A large tract of pristine in company with B. nitidus with no apparent premontaneand montaneforest remainson the interaction. southernslope of Zunil and the easternface of Vol- 7) Buteomagnirostris: occasionally observed perched can Santa Maria, althoughconditions described by or soaring near B. nitidus. No aggressionhas Jenny and Cade (1986) as required for Orange- been noted. breastedFalcons have not beenpresent for decades. 8) Buteo nitidus: see C. aura, C. atratus, B. brach- yurus and B. magnirostris.B. nitidusare com- Peregrine Falcon (F. peregrinus) monly observedadjacent to other soaringrap- Probable.Peregrines are now known to occurat torswith no signsof interestor aggression.Faro a variety of elevationsand habitats in Guatemala has high populationdensities and intraspecific 34 J^¾ P. V^NNINI VOL. 23, No. 2

aggressionamong unpaired B. nitidusis intense. though it has long been suspectedthat speciessuch A climax plantation area at 1100 m is partic- as Buteo rnagnirostris,Elanus caeruleusand Falco ularly subjectto confrontationsbetween a res- rufigularisare expandingtheir rangesparallel to the ident pair and intruders.Up to four birdswere agricultural frontier (Land 1970; Cade 1982), ob- observeddisputing this area on different dates servationspresented in this studysuggest that other during March 1988. diurnal raptor speciesmay benefit from habitat 9) Buteo su•ainsoni: see C. aura. transformation.Comparative studiesat parks and 10) Spizaetustyrannus: see A. striatus. reserves with similar elevations and biotas would be 11) Herpetotherescachinnans: see C. aura. of considerablevalue (e.g., Parque Nacional Braulio 12) Polyborusplanca: see C. aura. Carillo, ). A comparisonof the avifauna and diurnal raptor DISCUSSION faunas of 5 Central American parks and reserves Thiollay (1985a) listed 37 Neotropical diurnal and 6 political regionsin the northern and middle raptorswhich he considerstropical rainforestspecies. Neotropics is presentedin Tables 1-2. A clear re- Four are identified as being associatedwith small lationship existsbetween the total known avifaunal clearings,edges, etc., and selectniches are suggested componentof Guatemala, Costa Rica and Panam• for many of these "rainforest" species(Thiollay and the percentagecomposition of respectivediurnal 1985b). Field observationsof Neotropical raptors raptor faunas.Compared to theseMiddle American over a 13-yr period and commentsby other re- regions, (to the north), and searcherslead me to believethat groupingsare large- (to the south)have a significantlylower percentage ly artificial. Although there is no way of examining of diurnal raptor specieswhen comparedto total precolumbianhabitat partitioning in Neotropical known avifauna.It would be interestingto studythe raptors,extensive use of "atypical"habitat (dry for- reasonsbehind the fact that Middle America pos- ests,plantations), in areasoften adjacentor closeto sessessuch statistically diverse diurnal raptor faunas. pristinetropical moist or wet forestsinfers a certain Percentagerelationships between the parks and degreeof adaptabilityto changes.I acknowledgethat reserves listed in Table 1 at lower elevations are suchmay not be sofor all taxa. Sevenof the species closerthan thoseof 2 premontanereserves (Faro/ identified as tropical rainforestindicator speciesby Monteverde).Interestingly, 2 factorscommonly cit- Thiollay occur on Finca E1 Faro in successional ed as being of primary importancefor preservation vegetationand varying types of plantation. I em- of diversityin the Neotropics(i.e., sizeand latitude), phasizethat much of the vegetationat Faro may be do not appear to be of real importance(Willis 1974; dated. Furthermore, a careful examination of re- Thiollay 1985a). Finca E1 Faro and Finca La Selva gional works on Neotropicalavifauna revealsa num- are the smallestreserves listed in this study,yet have ber of observations and collections made of these the highestnumber of diurnal raptor speciesfor their same speciesin degradedhabitat (e.g., Wetmore elevational groups (premontane and tropical, re- 1965). spectively)in addition to being rich in total avian Finca E1 Faro has a known diurnal raptor fauna diversity(Stiles 1977; Vannini 1989). that includes21 species.Ten speciesare resident Clearly, factorsother than size and latitude must which have been observedat different times during be taken into accountwhen discussingbiodiversity the courseof this study; 5 speciesare infrequently potential in Central America. Although size of re- observed transients; 5 are long-distance migrants servesis of undoubtedimportance throughout the which were observedfrom Octoberto May, and 1 Neotropics(Lovejoy et al. 1984), biogeographyand has both residentand migrant populations. elevation are of primary importance in Central Faro providesa unique opportunityto study na- America. Both E1 Faro and La Selva are located in tive vertebratesunder a variety of conditionsand regionsof high vertebratediversity, with corridors elevations.Vegetational successionstudies are being of mature vegetation connectedto highlands. Im- effected on both man-altered habitats and forest de- portanceof vegetationalcorridors in maintaining di- stroyedby the 1973 nu•e ardenteof Volcan Santia- versebiotas has only recentlybegun to be understood guito. I am not aware of any studiesmade on diurnal (Hartshorn 1983). Stiles (1985) studiedlocal move- raptorsin the Neotropicsalong an elevationaltran- mentsin hummingbirds(Family Trochilidae) and sect,or communitystudies in degradedhabitat. AI- foundthat elevationalmigrations effected seasonally o [-.-.- o un o ',..o un ('• o c',,I .,.-, ',..o 36 JAY P. VANNINI VOL. 23, NO. 2

Table 2. A comparisonof avifaunaldiversity and diurnalraptor diversity in 6 countriesin the neotropics.

TOTAL KNOWN TOTAL NO. OF SPECIES AVIFAUNAL OF DIURNAL RAPTORS COUNTRY COMPONENT(TKAC) (TNDR) ø70TNDR/TKAC Mexico 1 1018 58 5.70% Guatemala2 714 49 6.86% Costa Rica3 820 53 6.46% Panama4 883 55 6.23% Colombias 1695 75 4.42% Peru6 1689 71 4.20% References:• Peterson and Chalif 1973; 2 Land1970; Vannini unpubl. ms.; 3 Stiles1983; 4 Ridgely1976; s Hiltyand Brown 1986, 6 Parker et al. 1982.

are the rule for manytaxa. Similarly,Janzen (1986) plantations on Guatemala's Pacific versant differed discussedthe importanceof corridor-linkedpre- little, if at all, from that of adjacentforest. Many montanehabitats in Cordillerade Tilarfin with dry raptors may be able to maintain viable breeding forestlowlands of GuanacasteNational Park in pre- populationsin areaswhich have suffereddegrada- servingdiversity. Thus E1 Faro and La Selva,while tion, yet offer active protectionto both prey and smallreserves, benefit from the pristine"sanctuary predator. Craighead and Craighead (1956) stated areas"which lie above,namely Volcan SantaMaria that raptor populationsare relatedto vulnerability and the CordilleraCentral, respectively. Tikal and of prey, rather than prey densitiesin a given area. Monteverdeare convenient"tourist" parks,selected Successionaryvegetation undoubtedly increases prey with criteria differentfrom thoseprevalent at Faro, vulnerability and coupledwith high densitiesof a La Selva or Pipeline Road. That Tikal and Mon- highly diverseprey basemay accountfor diurnal teverdeare alsolarger and more interestingto the raptor diversityat E1 Faro. lay visitorhas no bearingon speciesdiversity, a fact I concludethat a biasby researcherstowards work which shouldnot be lost on organizationswith an in mature, lowland forests in Central America re- interest in wildlands and wildlife preservationin sultsin an assumptionthat environmentallysensitive Central America. ,including many diurnal raptors,can ex- Why Faro possessessuch a diversediurnal raptor ist only as associatesof pristine habitat. I predict fauna remainspoorly understood. While elevational that more researchin plantationsand otherwise rangeon the farm andthe biogeographyof the west- modifiedhabitats in the northernNeotropics will ern highlandspoints towards diversity, conventional reveala greaterdegree of adaptabilityin manydiur- wisdomregarding agricultural transformation in the nal raptor speciesthan has previouslybeen sus- Neotropicsand subsequent impacts on wildlifepoint pected. towardsa depauperatefauna. Assumptions based on conventionalwisdom would imply that Faro has no SUMMARY value as a reserve. While we haveno way of knowingwhat original Observations at Finca E1 Faro have revealed the vertebratedensities were in plantation areas, I sus- presenceof 4 diurnal raptor speciesnot previously pectthat the actualsituation does not mirror pristine recordedfrom the westernhighlands of Guatemala, habitat.Although a numberof environmentallysen- 2 speciesnot previouslyrecorded from Guatemala's sitive vertebratesmaintain breeding populations Pacificversant and 1 elevationalrecord (Land 1970). (Pharomachrusmocinno, Crax rubra, Vampyrum spec- It is unlikely that thesedistributional records rep- trum,Plectrohyla avia, etc.) numbers may be far low- resentlocal displacement;there are large tractsof er than original densities.Undoubtedly, other taxa, pristine premontane forest within 8 km airline of E1 includingmany diurnal raptors,have benefitted from Faro. Due to the natureof the faunal inventory,no agricultural transformationwhile othershave main- attemptwas made to seeknests, but courtshipdis- tainedstable populations. As early as 1932, Griscom playsand juvenile birds observed suggest that further notedthat the avifaunalcomponent of mature coffee investigationwill reveal nestingdiurnal raptors. SUMMER 1989 NEOTROPICALRAPTORS 37

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