j. RaptorRes. 36(1):51-57 ¸ 2002 The Raptor ResearchFoundation, Inc.

RAPTOR ABUNDANCE AND HABITAT USE IN A HIGHLY-DISTURBED-FOREST LANDSCAPE IN WESTERN

NATHANIEL E. SEAVY• AND CHRISTINE K. APODAC^ Departmentof Zoology,223 BartramHall, P.O. Box 118525, Universityof Florida, Gainesville,FL 32611-8525 U.S.A.

ABSTRACT.--Weconducted roadsideraptor surveysin an area of western Uganda that included undis- turbed forest, agriculturalmosaics, and tea plantations.Between September 1997-April 1998, we sur- veyed three transects(51 km of roadway)twice each month, once during the morning and again in the afternoon. During these surveys,we detected 14 falconiform speciesand 77 individuals.We detected significantlymore raptorsduring morning than afternoon surveys.Wahlberg's (Aquila wahlbergi) and Long-crestedEagles (Lophaetus occipitalis) were observedmost frequently and were sightedconsis- tently throughout the study.Most raptors observedwere resident ,whereas Palearctic migrants comprisedless than 25% of all raptors,noteworthy considering their abundancein other African re- gions.We did not detect an equal number of raptors in all habitat types.Agriculture mosaicsaccounted for 61% of the habitatwe surveyedand 75% of all raptor detectionswere in thesehabitats. In contrast, tea plantationswere 14% of the area surveyed,but only 3% of all raptorswere detected there. Based on these results,we suggestthat tea plantations may be suboptimal habitat for larger, open-habitat raptors. We did not detect large, forest-dwellingeagles outside of large areas of undisturbed forest, which are probablycritical to their persistencein these landscapes. KEYWORDS: Uganda;roadside survey; conservation; habitat use,, deforestation; tea plantation; Aquila wahlbergi; Wahlberg'sEagle,, Lophaetus occipitalis; Long-crested .

Abundancia de repacesy uso de habitat en un paisajede bosque altamente disturbadoen el oeste de Uganda RESUMEN.--Hicimosestudios de rapacesalrededor de las carreterasen un •trea del oeste de Uganda que inclunabosque sin intervenci6n,mosaicos agrfcolas, plantaciones de te. Entre septiembrede 1997- abril de 1998, estudiamostres transeptos(51 km de carreteras) dos veces cada mes, una vez en la mafianay otra en la tarde. Durante estosestudios detectamos 14 especiesfalconiformes y 77 individuos. Detectamossignificativamente m•ts especies durante los estudiosde la mafiana queen los de la tarde. Las ftguilasde Wahlberg (Aquila wahlbergi)y las ftguilasde crestaalargada (Lophaetusoccipitalis) fueron observadasrafts frecuentemente y fueron avistadasconsistentemente a lo largo del estudio.La mayoria de rapacesobservadas fueron especiesresidentes, mientras que las migratoriaspalearticas comprendie- ron menos del 25% de todas las rapaces,esto es digno de mencionarlo considerandosu abundancia en otrasregiones africanas. No detectamosun nfimero igual de rapacesen todoslos tipos de h•tbitats. Losmosaicos agricolas dieron cuentade 61% del h•tbitatque estudiamosy 75% de todaslas detecciones de rapacesestuvieron en esosh•tbitats. En contraste,las plantacionesde te fueron 14% del •trea estu- diada, pero 6nicamente 3% de todas las rapacesfueron detectadasalli. Basadosen estosresultados, sugerimosque las plantacionesde te pueden ser habitatssub 6ptimos para las rapacesm•ts grandes y de habitats abiertos. No detectamosgrandes •tguilasresidentes de bosque fuera de grandes •treasde bosqueno perturbado, los cualesprobablemente son criticospara su supervivenciaen estospaisajes. [Traducci6n de CdsarMarquez]

When coinpared to Nearctic and Palearctic spe- edge of 79 raptors breeding in East Africa, they cies, Afrotropical raptors are relativelyunstudied. considered only 6.3% of these species "well- This deficiency was recently illustrated by Virani known,"while rating 60.8% "unknown."For many and Watson (1998); describing the state of knowl- of theseunknown species, little or no information exists on distribution, abundance, breeding biolo- 1 E-mail address:[email protected] gy,or feeding ecology--basicinformation for iden-

51 52 SE^vY ^ND APOD^CA VOL. 36, No. 1 tifying populations that are threatened by habitat the Makerere University Biological Field Station in KNP, alteration. Determination of populations that are averaged1778 mm between 1990-98 (L. Chapmanand C. Chapman unpubl. data) and peak periods of rainfall threatened is an important aspectof conservation, occurin April and October (Struhsaker1997). especiallyin areaswhere forestsare being cleared We conducted roadside raptor surveysalong three to support growing human populations. transects(19, 15, and 17 km in length; Fig. 1) between With ca. 104 people per kme, Uganda has one September1997-April 1998. We surveyedtransects twice of the densest populations in sub-SaharanAfrica each month, once in the morning (between 0800-1000 H) and again in the afternoon (between1500-1700 H), and it continuesto grow at a yearly rate of 2.6% usuallyon the sameday. Driving at speedsof 20-40 km/ (FAO 1999). This population has driven wide- hr with five observersin the vehicle, we stoppedbriefly spread deforestation. A hundred years ago, ca. to identify raptors on both sidesof the transectand re- 13% of Uganda was covered by moist, broadleaf corded the time, distancefrom the transect,habitat type, forest, but only 3% of this forest remains (Sayeret and activity (perched or flying) for each . During heavy rain we did not conduct surveys. al. 1992). The remaining forested areas, many in To quantify habitat availability, we visually estimated reservesand national parks, are under increasing habitat composition(10% increments)within 100 m of pressurefrom growingrural populations.Thus, in- either side of the road of each km traveled. For this anal- formation on raptor abundance and habitat use ysis,we recognized eight habitat types:mature forest, ag- both inside and outside of these protected areas is riculture/forest mosaic, agriculture/grassland mosaic, tea plantation, secondary vegetation, villages, papyrus important for management and conservationde- swamp,and lakeshore.MatureJbrest was primarily encoun- cisions. tered when transectspassed through portions of Kibale Roadside raptor surveyshave been widely used National Park. This forest is consideredmoist, evergreen to study relative abundance, community composi- forest, transitional between lowland rainforest and mon- tion, and habitat use of raptors (e.g., Woffinden tane forest (Struhsaker 1997). Canopy height ranges from 25-30 m, with a few trees as tall as 55 m, and com- and Murphy 1977, Ellis et al. 1990). Although lim- mon tree speciesinclude Diospyrosabyssinica, Markhamia itations of roadside surveys are well-recognized platycalyx,Celtis durandii, Uvariopsiscongensis, and Bosqueia (Millsap and LeFranc 1988, Bunn et al. 1995), the phoberos(Chapman et al. 1997). Agriculture/Jbrestmosaic method offers an efficient meansof describingrap- was characterizedby a patchwork of remnant forest frag- tor communities. Roadside raptor surveys have ments surrounded by subsistenceagriculture (primarily bananas, millet, cassava, and corn), fallow fields domi- been conducted in East Africa (Brown 1971, Thio- nated by elephant grass (Pennisetumpurpureum, 3-5 m 11ay1978, Sorley and Andersen 1994), but these tall), cattle pasture, pine and eucalyptusplantations, and efforts have occurred mostly in savannahabitats scatteredhouses. Similar to this habitat, agriculture/grass- that are characterized by high densities of large land mosaicwas also a patchwork of farmland, cattle pas- mammals, vultures, and eagles. Here we present ture, and forest plantations, but uncultivated land was covered by large areas of elephant grass,and there were results from eight months of roadside raptor sur- no remaining natural forest fragments.Agriculture/grass- veys in the Kabarole District of western Uganda. land mosaicoccurred in the southern portion of the study We describe the abundance and diversityof raptors area. Teaplantations are large fields of tea shrubs grown in mature forest, agriculture/forest mosaic, agri- in rows and trimmed regularly to maintain a uniform culture/grasslandmosaic, tea plantation, second- height of about 1 m. This crop is one of the few intensive, large-scale agricultural industries in western Uganda. ary vegetation,villages, papyrus swamp, and lake- Four other habitat types--secondaryvegetation, villages, pa- shore habitats. pyrusswamp, and shoresof cT'aterlakes•together comprised <10% of the area surveyed. STUDY AREIX AND METHODS Becausethe number of raptors detected per transect The studyarea (0ø13'-0ø41'N,30ø19'-30ø32'E) lies just waslow, we pooled surveyresults from the three transects north of the equator at the foot of the Ruwenzori Moun~ and considered them a single transect, though surveyed transin western Uganda (Fig. 1). This area is volcanic in on different days.We considered monthly surveysinde- origin and characterizedby rolling hills. Elevationranges pendent samplesand used a Wilcoxon signed-rankstest from 1100 m in the south to 1590 masl in the north. to compare distributions of raptor count data from Although historicallyforested, much of the land hasbeen morning and afternoon surveys.We investigated the re- cleared for subsistencefarming and banana (Musa spp.) lationship between monthly rainfall and raptor detec- and tea ( Theasivensis) plantations to support the growing tions (morning and afternoon surveyspooled) using human population. Within this agricultural landscape, Spearman rank correlation. We used Chi-squaregood- forest fragments remain, especially on steep slopes ness-of-fittests to compare observed and expected num- around crater lakes (Onderdonk and Chapman 2000), bers of raptors among months and habitat types (all but the onlyextensive forested area is within the 766 km2 months pooled). We recognize that pooling survey re- K•bale National Park (KNP). Yearlyrainfall, measuredat suits violates conditions of statisticalindependence, but IVI•CH 2002 SURW• IN A DISTURBED-FOREST LANDSCAPE 53

Kibale National Park Uganda

N

/ ...'•..SurveyRoad Route [

Scale (km)

Figure 1. Map of studyarea and roadsidesurvey transects in Kabaroledistrict, Uganda.

our limited sample size prevented us from using other RESULTS AND DISCUSSION techniquesto compare data. To meet the assumptionsof the Chi-squaregoodness- We observed14 falconiform speciesand 77 in- of-fit test for the habitat analysis,we combined habitat dividualsduring our study (Table 1). During morn- typesthat made up lessthan 5% of the transectlength ing surveyswe detected more raptors (median = (secondaryvegetation, villages, papyrus swamp, and lake- shore) into one category,so all categorieshad >5 ex- 5.5, i = 6.5 raptors/survey)than during afternoon pected detections.Differences between observed use and surveys(median = 2.5, i = 3.1, Wilcoxon signed- availabilitymay occur if raptor detectabilityvaries system- ranks test, z = -2.54, N = 8, P < 0.05). This dif- atically among habitat types.To evaluatewhether detect- ference is consistentwith temperate zone studies abilityvaried among habitats,we compareddetection dis- demonstrating that roadside raptor surveysare af- tances (Kruskal-Wallis test) for mature forest, agriculture/forestmosaic, and agriculture/grasslandmo- fected by raptor activity patterns (Bunn et al. saic.Significance level for all testswas P = 0.05. 1995). The mean number of detections per month Finally,based on eight months of pooled data, we pre- was 8.0 raptors, ranging from 5 (December) to 20 sent three measures of relative abundance to facilitate (October). The number of detections in October comparisonto other roadside raptor literature: (1) indi- was inflated when we observed 13 Common Buz- viduals detected per km traveled, (2) km traveled per individual detected, and (3) Woffinden and Murphy's zards (Buteobuteo vulpinus) migrating southward. (1977) Index of Relative Abundance (IRA), calculated as: When these sightings were omitted there was no significantdifference between the number of rap- No. ind. of each speciesobserved tors detected each month (X27 = 4.25, P > 0.05). IRA = X 1000 No. km traveled There was no relationship between monthly rain- 54 S•^vY AND /SG'ODACA VOL. 36, NO. 1

Table 1. Numbers of raptors detected, detection frequencies, and relative abundance indices of raptors during roadside surveysin Kabarole district, Uganda.

INDEX OF NO. IND1V. PER Km TR•V. REL. SPECIES OBSERVED km PER INDIV. ABUND. a

Black-shouldered Kite (Elanus caeruleus) 3 0.004 272.0 3.7 (Milvus migrans) 5 0.006 163.2 6.1 Afi:ican Fish-Eagle ( Haliaeetusvocifer) 1 0.001 816.0 1.2 Palm-nut Vulture ( Gypohieraxangolensis) 3 0.004 272.0 3.7 Afi:ican Harrier-Hawk (Polyboroides typus) 4 0.005 204.0 4.9 Unidentified harrier (Circusspp.) 1 0.001 816.0 1.2 Afi:ican Goshawk ( Accipitertachiro) 2 0.002 408.0 2.5 L•zard ( Kaupifalcomonogrammicus) 2 0.002 408.0 2.5 Common (Steppe) Buzzard (Buteobuteo vulpinus) 14 0.017 58.3 17.2 Wahlberg'sEagle (Aquila wahlbergi) 18 0.022 45.3 22.1 Long-crestedEagle (Lophaetusoccipitalis) 16 0.020 51.0 19.6 Crowned Hawk-eagle (Stephan0aetuscoronatus) 2 0.002 408.0 2.5 Gray Kestrel (Falcoardosiaceus) 2 0.002 408.0 2.5 Northern (Falcosubbuteo) 1 0.001 816.0 1.2 Unidentified hobby (E subbuteoor cuvieri) 3 0.004 272.0 3.7 Analysisof relativeabundance after Woffindenand Murphy (1977). f•tll and the number of raptors detected (h = 0.13, surveyed,but only 3% of all raptor detections.In N = 8, P = 0.76). Omitting the October flight of this habitat, we detected0.02 raptors/km amdonly Common Buzzardsdid not change the significance a single species,the small, insectivorousGray Kes- of this relationship(rs = -0.12, N -- 8, P = 0.77). trel (Falcoardosiaceus; Table 2). Larger, vertebrate- Raptorswere not equallyabundant in all habitats eating raptors were conspicuouslyabsent fi:om tea (X24= 19.0, P < 0.05). However, the detection dis- plantation habitats, despite the fact that these tances fbr mature fbrest (median = 0, • = 0.9 m, fields were often bordered by fbrest fi:agmentsor N = 9), agriculture/fbrest mosaic (median = 40, crossedby rows of utility poles, providing suitable œ = 44.7 m, N = 31) and agriculture/grassland perches. mosaics(median = 40, œ= 64.2 m, N = 27) were In mature fbrest we detected only Crowned significantlydifferent (Kruskal-Wallis,//'2 = 20.26, Hawk-Eagles (Stephanoaetuscoronatus) and Com- P < 0.05). As a result, raptor detectabilitywas un- mon . All observations (N = 7) of Com- doubtedlyreduced in fbrest habitats,but when fbr- mon Buzzards in this habitat occurred during a est habitat was excluded fi:om the analysis,raptor singlesurvey in October while this specieswas pass- detections were still not equally abundant in all ing through on migration. Common Buzzardsnor- habitats (X2• = 15.57, P < 0.05). Therefbre, we do mally winter in open savannahabitats throughout not believe that this result simply reflects differ- Africa, and their occurrence in this fbrested area ential detectability. wasprobably an unusualevent associatedwith mi- Agricultural/fbrest mosaic was the most com- gration. In contrast, Crowned Hawk-Eagles are mon habitat along the route and accordinglyhad breeding residents in KNP, where they prey pri- the greatestspecies richness (N = 8) and total de- marily upon arboreal monkeys (Skorupa 1989, M•- tections (N = 31; Table 2). Agriculture/grassland tani et al. 2001). The absence of Crowned Hawk- mosaichad the secondhighest speciesrichness (N Eagles outside of mature forest suggeststhat they = 6) and total number of detections (N = 27; Ta- may be sensitiveto defbrestation in this region of ble 2). However, detectionsper km were higher in Africa, perhaps becausemany primates are absent agriculture/grasslandmosaic (0.17 raptors/km) fi:om fbrest fi:agmentsoutside of the park (Onder- than in agriculture/fbrest mosaic (0.09 raptors/ donk and Chapman 2000). km). The least common habitat, lakeshore, occurred Tea plantationsaccounted fbr 14% of the area only where one transectpassed a small crater lake MARCH 2002 SURVEYSIN A DISTUP,BED-FOREST LANDSCAPE 55

Table 2. Number of raptorsobserved in eight habitat typesduring roadsidesurveys in Kabaroledistrict, Uganda.

HABITAT TYPE a

SPEcms AFM AGM TP MF VI SV PS 1,S

Black-shouldered Kite 3 Black Kite 3 African Fish-Eagle Palm-nut Vulture African Harrier-Hawk 3 1 Unidentified harrier 1 African Goshawk 2 Lizard Buzzard 2 2 3 7 1 I Wahlberg'sEagle 2 16 Long-crestedEagle 13 3 Crowned Hawk-Eagle Gray Kestrel Northern Hobby 1 Unidentified hobby 3

Total species 8 6 1 2 2 I 2 Total individuals 31 27 2 9 3 1 4 Raptorsper km 0.09 0.17 0.02 0.06 0.10 0.05 0.0 1.25 Km habitat surveyed 337.6 160.0 110.4 148.8 28.8 22.4 4.8 3.2 Percent of total survey length 41.4 19.6 13.5 18.2 3.5 2.8 0.6 0.4 Habitat types:AFM = Agriculture/forest mosaic,AGM = Agriculture/grasslandmosaic, TP = Tea plantation, MF = Mature forest, VI = Village, SV = Secondaryvegetation, PS = Papyrusswamp, and LS = Lakeshore.

and accountedfor <1% of the habitat surveyed. is difficult, because some or all of the unidentified However, this habitat was the only area where we raptors (e.g., Circusspp. and Falcospp.) may have observed an African Fish-Eagle (Haliaeetusvocifer) been migratory and some species,such as Black and Palm-nut Vultures ( Gypohieraxangolensis; Table Kites (Milvus migrans),may have been represented 2). by both migrant (M. m. migrans)and resident (M. Long-crested Eagles (Lophaetusoccipitalis) and m. parasitus)subspecies. However, even if we as- Wahlberg'sEagles (Aquila wahlbergi)were the most sume that all unidentified specieswere wintering abundant raptors,accounting for 34 of 77 (44%) Palearctic migrants, these individuals account for raptors detected (Table 2). We observed no true only 8% of all raptor detectionswhen Common vultures during our surveys,despite the fact that Buzzards are omitted. Brown (1971) recorded four vulture speciesduring Basedon raptor surveysin Mexico, Guiana, and roadsidesurveys in Queen ElizabethNational Park, , Thiollay (1985) demonstrated that less than 50 km south of our study area. Most when tropical forestsare fragmented and convert- (75%) of the raptors we observedwere either res- ed to open agricultural habitats, resident species identsor intra-Africanmigrants. The other 25% of tolerant of open habitats and northern migrants detectionswere Palearctic migrants, but this per- replace resident forest species.Similarly, in a re- centageis inflated by migrating Common Buzzards view of roadside raptor surveysin , that did not have a sustainedpresence in the area. Cade (1969) recognized that Palearctic migrants Thus, the proportion of migrant specieswintering were abundant in the disturbed agricultural habi- in the area was much lessthan 25%, even though tats of Transvaal and Orange Free State, where they our surveystook place during the Palearcticwinter accountedfor 33-95% of all raptor detections,but when northern migrantswould be present. Deter- were relatively rare in Kruger National Park and mining the exact proportion of wintering migrants Kalahari Gemsbok Park, where they accounted for 56 S}•^w •ND APOD^C• VoI•. 36, No. 1 only 2-4% of all detections.In savannahabitats of unsuitable habitat for many larger, open-habitat Uganda, Palearcticmigrants comprisedonly 11% raptors.In short, not all open habitatsare of equal of the raptorsdetected by Brown (1971) and 31- value to all open-habitat raptors. These results 43% of raptors detectedby Thiollay (1978). Most shouldbe consideredby managersand researchers of our study area was deforested and highly-dis- concerned with raptor conservationand protected turbed, and although the commonly-detectedres- area design in forested landscapesof East Africa. idents were associatedwith open, agricultural mo- ACKNOWLEDGMENTS saichabitats, we did not observea large proportion of wintering migrants. Invaluable assistancein the field was provided by E. Roadsideraptor surveysgenerally work well in Aliganyiri, S. Balcomb, A. Ermosi, T. Lawrence, and J. Mugenyi. We thank LJ. Chapman and C.A. Chapmanfor open habitats; however, they are less effective in support of this project. We expressour gratitude to the forestedhabitats (Millsap and LeFranc 1988). This Makerere UniversityBiological Field Station for provid- may be especiallyproblematic in tropical forests ing logisticalsupport in Kibale National Park. J. Piascik where raptor communitiesare notoriouslydifficult prepared the figure of the study area. C.A. Chapman, to sample and complete surveysoften involvespe- R.S. Duncan, P. Mundy, J. Paul, D.F. Whitacre, and two anonymous reviewersprovided comments on drafts of cial techniques (Thiollay 1989, Whitacre et al. the manuscript. 1992). Thus, the low number of raptorswe detect- ed in mature forest is probably not indicative of LITERATURE CITED overall raptor abundance and speciesrichness in B•tOWN,L. 1971.African birdsof prey.Houghton Mifflin this habitat. For instance, we did not detect Cas- Co., Boston, MA U.S.A. sin's Hawk-Eagles (Spizaetusafricanus) nor Ayres' BUNN, A.G., W. KLEIN, AND K.L. BII.DSTEIN. 1995. Time- Hawk-Eagles(Hieraaetus ayresii). Both are large,un- of-day effects on the numbers and behavior of non- common, forest-dwellingeagles that breed in Ki- breeding raptors seen on roadside surveysin eastern bale National Park (Skorupa et al. 1985, Seavy Pennsylvania.J. Field Ornithol.66:544-552. 2000). Similarly, smaller raptors that use easily CADE,T.J. 1969. The statusof the peregrine and other overlooked perch sitesare often difficult to detect Falconiformesin Africa. Pages289-321 inJ.J. Hickey [ED.], Peregrine populations, their biology (Millsap and LeFranc 1988) and these biases and decline. Univ. of Wisconsin Press, Madison, WI should be consideredwhen interpreting our survey U.S.A. results. Species that were observed in the study CH•M•, C.A., LJ. CHAPMAN,R.W. WRANGHAM,G. ISA- area, but not detected on our transects, were Os- 13IP,•-BASUTA,ANt) K. BEN-D^•t). 1997. Spatial and prey (Pandionhaliaetus), Banded Snake-Eagle(Cir- temporal variability in the structure of a tropical for- caetuscinerascens), Black-chested Snake-Eagle ( Cir- est. Afr.J. Ecol.35:287-302. caetuspectoralis), African Marsh-Harrier (Circus ELLIS,D.H., R.L. GI,INSKI,AND D.G. SMITH. 1990. Raptor ranivorus), Black Goshawk( Accipitermelanoleucus) , road surveysin South America. J. RaptorRes. 24:98- ( minullus), Martial Ea- 106. FAO. 1999. State of the world's forests. 1999. United Na- gle (Polemaetusbellicosus), and African Hobby (Falco tions, Rome, Italy. cuvieri). MILLSAP,B.A. ANDM.N. LF•F•NC, JP,.1988. Road transect The results of our surveysprovide two conclu- cout)tsfor raptors:how reliable are they?J. RaptorRes. sionswith implicationsfor raptor conservationin 22:8-16. East African fbrest landscapes.First, in the domi- MITANI,J.C., w.J. SANDERS,J.S. LWANGA,AND T.L. WIND- nant agricultural habitat we detected speciesasso- FELDER.2001. Prcdatory behavior of Crowned Hawk- crated with agricultural habitats, but very few for- Eagles (Stephanoaetuscoronatus) in Kibale National est-associatedspecies. Thus, althoughsome raptors Park, Uganda. Behar.Ecol. Sociobiol. 49:187-195. may be numerous in these cleared habitats,forest- ONDERDONK,D.A. ANDC.A. CHAPMAN.2000. Coping with associatedspecies appear to be uncommon, re- forest fragmentation:the primatesof Kibale National stncted to large tracts of forest, and sensitiveto Park, Uganda. Int. J. P•imatol.21:587-611. SAyE•,J.A.,C.S. HAUtOUST,AND N.M. COLt.INS. 1992. The deforestation. If the large, forest-dwellingraptors conservationatlas of tropical forests:Africa. Macmil- are entirely absentfrom open habitatssurrounding lan, U.K. KNP, then these speciesmay be confined to the SFAVY,N.E. 2000. Observationsat an Ayres' Hawk-Eagle forest inside the park. Second, our resultssuggest nest in Kibale National Park, Uganda. J. RaptorRes. that tea plantations may provide unique foraging 34:59-60. opportunities for small insectivorousraptors, but S•:OP,UPA, J.P. 1989. Crowned Eagles Stephanoaetuscorona- MARCH 2002 SURVEYSIN A D•STURBED-FOREST LANDSCAPE 57

tusin rainforest:observations on breedingchronology prey: conservation studies on raptors. ICBP Tech. and diet at a nest in Uganda. Ibis 131:294-298. Publ. No. 5, Cambridge, U.K. , J. KALINA,T.M. BUTYNSKhG. TAgOR,AND E. KEL- 1989. Censusingof diurnal raptors in a primary t.OC. 1985. Notes on the breeding biologyof Cassin's rainforest:Comparative methods and speciesdetect- Hawk-EagleHieraaetus africanus. Ibis 127:120-122. abilityßJ. RaptorRes. 23:72-84. SORLEY,C.S. AND D.E. ANDERSEN.1994. Raptor abun- VIRANI,M. AND R.T. WATSON.1998. Raptors in the east dance in south-centralKenya in relation to land-use African tropics and western Indian Ocean islands: patterns.Afr. J. Ecol.32:30-38. stateof ecologicalknowledge and conservationstatus. STRUHSAKER,T.T. 1997. Ecologyof an African rainforest: J. RaptorRes. 32:28-39ß logging in Kibale and the conflict betweenconserva- WHITACRE,D.F., L.E. JONES,ANDJ. SUTI'ER.1992. Census- tion and exploitationßUniv. Pressesof Florida, Gaines- ing raptors and other in tropical forest:further ville, FL UßSßA. refinementsof methodology.Pages 39-52 in D.F. Whi- THIOLLAY,J.-M. 1978. Populationstructure and seasonal tacre and R.K. Thorstrom [EDS.],Maya Project Report fluctuationsof the Falconiformesin Uganda National No. 5. The Peregrine Fund, Boise, ID U.S.A. Parks.E. Afr. Wildl.J. 16:145-151. WOFFINDEN,N.D. ANDJ.R.MUP, PH¾. 1977. A roadsiderap- ß 1985. Compositionof Falconiform communities tot censusin the easternGreat Basin--1973-74.Rap- along successionalgradients t?om primary rainforest tot Res. 11:62-66. to secondaryhabitats. Pages 181-190 in I. Newton and R.D. Chancellor [EDS.], World conference on birds of Received 25 January 2001; accepted 21 November 2001