j RaptorRes. 37(3):228-235 ¸ 2003 The Raptor ResearchFoundation, Inc. NEST AND ROOST HABITAT CHARACTERISTICS OF THE GREY-FACED BUZZARD IN NORTHEASTERN CHINA WEN-HONG DENG 1 Ministry of EducationKey Laboratory for BiodiversityScience and EcologicalEngineering, College of Lij•bSciences, BeijingNormal University,Beijing, 100875, China GAO WEI Schoolof Li•[bSciences, Northeast Normal University,Changchun, 130024, China ZHENG GUANG-MEI Ministry of EducationKey Laboratory for BiodiversityScience and EcologicalEngineering, College of Lij• Sciences, BeijingNormal University,Beijing, 100875, China ABSTRACT.--Thehabitat of the Grey-facedBuzzard (Butasturindicus) has diminished substantiallybe- causeof forest managementfor timber production and farmland reclamationin recent years.An un- derstandingof the characteristicsof nest and roost sitesof this bird is important for its conservation. We studiedGrey-faced Buzzards during their breeding seasonin Zuojia Nature Reserve,Jilin Province, China, from March 1996-August 1998. This speciesselected both nesting and roosting sitesin mixed- deciduousforests that containedKorean larch (Larix olgens)more frequently than availablein the study area.Most nests were located in Koreanlarches and in Chinesepines (Pinus tabulaeformis; 70%), whereas nestsin broadleaftrees were relativelyinfrequent (30%). Eight nests(75%) were locatedon the upper third of a slope,three nests(19%) were located on the middle third, and one nest (6%) on the lower third. Buzzardsused 11 tree speciesfor roosting;however, (58%) of all roostswere locatedin three tree species(Korean larch, Chinese pine, and River birch [Betulanigra] ). Higher canopyclosure and taller trees best separatedroost sitesfrom random plots with a discriminantanalysis. Mean roost height was 9.6 _+0.5 m. Roosttrees averaged11.2 -+ 0.6 m in height with mean DBH (diameter at breastheight) of 16.9 _+0.3 cm. Buzzardsselected nest and roost sitesin forestscharacterized by tall (>12 m) conifers, hardwoodunderstory, and high canopyclosure (>70%). I•Y WORDS: Butasturindicus; habitat use;, Grey-faced Buzzard; nest site;, nest tree;, roost site. CARACTERISTICAS DEL HABITAT DE LOS DORMIDEROS Y DE ANIDACION DEL BUITRE DE CARA GRIS DEL NORESTE DE CHINA RESUMEN.--E1habitat del buitre de cara gris (Butasturindicus) ha disminuidosubstancialmente en los filtimos aftos,a causadel manejo del bosquepara la producci6n de madera y la recuperaci6nde tierras para agricultura. Una comprensi6nde las caracteristicasde los skios de nido y de los dormiderosde esta ave, es importante para su conservaci6n.Estudiamos el buitre de cara gris durante su temporada de cria en la ReservaNatural de Zuojia, Provinciade Jilin, China, desde marzo del 1996 hastaagosto del 1998. Esta especieescogi6 sitios de anidaci6n y dormiderosen los bosquesdeciduos mixtos que contenian una mayor frecuencia de Larix olgensen el •irea del estudio. I,a mayorla de los nidos se localizaronen Larix olgensy Pinustabulaeformis; 70%, mientrasque los nidosque estabanen •irbolesde hojasanchas fueron relativamentepoco frecuentes(30%). Ocho nidos (75%) fueron localizadosen el tercio superiorde una pendiente,tres nidos (19%) fueron localizadosen el tercio medio, y un nido (6%) en el tercio inferior. Los buitresutilizaron 11 especiesde •irbolescomo dormideros;sin embargo el 58% fueron localizadosen tres especiesde •irbolesLarix olgens,Pinus tabulaeformisy Betula nigra. La cobertura del dosel y los arbolesmas altos fueron separadosde los dormideros mediante la utilizaci6n del analisisdiscriminante. La media de la altura de los dormiderosfue de 9.6 _+0.5 m. Los •irbolesque sirvieron como dormideros tuvieron una altura promedio de 11.2 -+ 0.6 m, con media DAP (di•imetro a la altura del pecho) de 16.9 _+0.3 cm. Los buitres escogieronnidos y dormideros en bosquescarac- 1 E-mail address:[email protected] 228 SEPTEMBER 2003 GREY-FACEDBUZZARD EAGLE HABITAT 229 terizadospor altas coniferas (>12 m), firbolesdel sub-dosel,de madera dura con copascerradas y altas (>70% alto de dosel). [Traduccitn de Casar Marquez] The large number of published reports that de- STUDY AREA scribe habitat selection and habitat characteristics The studyarea, ca. 84 km2 in size,was located in Zuojia among birds atteststo the enormousvariation ob- Natural Protection Area and included the Tumengling Mountains and Zhujia Mountains ranging from the east- servedand to the biologicalimportance of this top- ern ChangBai Mountains to the western plain (126ø1'- ic. In addition to its importance, an understanding 127ø2'N,44ø6'-45ø5'E). Elevation at the siteranged from of the responseby birds to environmentalhabitat 200-500 masl. The climate is east monsoon, character- ized by hot, dry summers and cold, snowywinters. The change is necessarybefore conservationstrategies vegetation within the study area was quite diverse, al- can be developed and implemented (Schmutz though the existing forest is secondary.The most com- 1989). A theoretical framework for habitat selec- mon trees present in the study area were Mongolian oak tion has been provided by Fretwell and Lucas ( Quercusmongolica), dahur birch (Betula davurica), Man- churian linden ( Tilia mandschmica),Japanese elm ( UImus (1970), and functionaland theoreticalaspects of japonica), Scotch pine (Pinus sylvestris),Korean larch (P•- habitat selection have been summarized by Gody nus koraiensis) and Masson pine (Pinus massoniana) (1985). Within these frameworks, nest and roost (Deng et al. 1997). In the studyarea, hawthorn raspberry characteristicsare very important factorsrelated to ( Rubus crataegifolius),dahurian rose (Rosa dahurica), Ko- rean rose (Rosadoreana), willowleaf spiraea ( Spiraeasah- arian habitat selection. cifolia),ural falsespiraea(Sorbaria sorbifolia), prickly rose Among subtropicalbirds, raptors are one of the (Rosaacicularis) , amur barberry ( Berberisamurensis) , amur least-studiedgroups and relatively little is known honeysuckle (Loniceramaacki), manchur honeysuckle about their nest and roost characteristics.Grey- (Loniceraruprechtiana), and sakhalin honeysuckle(LonG- ceramaximowiczii) dominated the shrub layer. The study faced Buzzard (Butastur indicus) is a summer mi- area consistsof ca. 30% open habitat and 70% forest grant in northeast China (Cheng 1987, Anony- habitat. mous 1988). It seemsthat most of the Grey-faced METHODS Buzzardsthat breed in northeastern China migrate Survey Methods. We surveyedthe study area at least to Okinawa, Taiwan, the Philippines, Indonesia, four times each year, 20 March-20 August, 1996-98, us- Malaysiaor nearbyregions to winter (Chang 1980, ing conventions suggestedby Newton and Marquiss Gheng 1987, Ehimekensibuet al. 1989, Deng et al. (1982) and Steenhof (1987) to describeoccupancy and 1997). This buzzard has been listed as a threatened activitiesat nesting sites.We attempted to locate all buz- zard nestswithin the studyarea. We used behavioral cues speciesin National SecondGlass Protected Species and systematicsearches of potential nest substratesto lo- in China Data Book of Endangered Animals cate nests.We determined the sex of buzzards by body (Zheng and Wang 1998). The habitats of this spe- size and plumage characteristics(Deng et al. 1997). We establishedsix transectsin the study area (2 = 3 km, cies have been substantiallyreduced because of range = 2-5 km). Each transectwas 50 m wide and par- forest management for timber production and allel to the forest edge. Each transect was divided into farmland reclamation in recent years (Zheng and 100 m segments from one end to the other. Sites were Wang 1998). An understanding of the characteris- surveyedwithin a 4-hr period beginning 30 rain after sun- rise by walking along each side, with 5-rain stopsat each ticsof nest and roostsites of this bird is particularly 100 m interval. We walked along one side and came back •mportant for its conservation.However, very little along another one. A nesting area was consideredoccu- is known about nestingecology of Grey-facedBuz- pied if a territorial pair or evidence of a territorial pair (such as observationsof an incubating bird, nest con- zards either in China or in other areas.In this pa- struction, or nest maintenance) was observed, otherwise per we describe the nest and roost characteristics the area was classifiedas unoccupied. We located roosts of this raptor in northeastern China. Our null hy- (the perch location where a bird spendsthe night) by potheses were: (1) no difference exists between observingbuzzards at roost sites.Only roost siteswhere buzzardsremained stationaryupon initial detection were nesting sitesand randomly-placedplots within the used in analyses.We recorded eagle nest and roost lo- study area, (2) no difference exists between the cationswith GPS receiversand plotted these on geologic immediate nest site and general habitat within nest surveymaps to the nearest 10 m using Universal Trans- stands, and (3) no difference exists between roost- verse Mercator (UTM) coordinates. Most of our habitat-sampling protocol was adopted ing sites and randomly-placedplots within the from Searoans and Gutitrrez (1995). We measured site study area. characteristicsin sample plots centered on buzzard nest 230 DENG ET AL. VOL. 37, NO. 3 trees and roost trees and at random locations in forest tween groups. We used cross validation (Capen et al. habitat. Detailed vegetationswere collected in 12 nest 1986) to evaluatethe stabilityof the DA model. stands and 12 random plots. Nesting habitat data were We took detailed measurementsof all nest trees (age, collected at