American black bears and bee yard depredation at Okefenokee Swamp, Georgia Joseph D. Clark1'4, Steven Dobey2, Darrin V. Masters3, Brian K. Scheick3, Michael R. Pelton2, and Melvin E. Sunquist3 1US GeologicalSurvey, SouthernAppalachianField Branch,274 EllingtonPlant Sciences Building, Universityof Tennessee, Knoxville,TN37996, USA 2Departmentof Forestry,Wildlifeand Fisheries, 274 EllingtonPlant Sciences Building, Universityof Tennessee, Knoxville,TN 37996, USA 3Departmentof WildlifeEcology and Conservation,Universityof Florida,Gainesville,FL 32611, USA Abstract: We studied American black bears (Ursus americanus), on the northwest periphery of Okefenokee Swamp in southeast Georgia, to assess landownerattitudestoward bars, estimate the extent of damageto commercialhoney bee operationsby bears, and evaluatemethods to reducebear depredationsto apiaries.We collected 8,351 black bear radiolocationsand identified51 bee yards on our study area.Twenty-sevenof 43 home ranges contained>1 bee yard, averaging 11.3 and 5.1 bee yards/home range of males (n = 7) and females (n = 20), respectively. From 1996 to 1998, we documented7 instances of bears raidingbee yards within our study area and 6 instances in adjacent areas.All but 1 of the 13 raidedyardswere enclosed by electric fencing. In the 12 cases of damageto electricallyfenced yards,however, the fences were not active because of depletedbatteries.Based on compositionalanalysis, bearuse of areas 800-1,400 m from bee yards was disproportionatelygreater than use 0-800 m from bee yards. Bears disproportionatelyused bay (red bay: Persea borbonia, loblolly bay: Gordonia lasianthus, and southernmagnolia:Magnolia virginia), gum (water tupelo: Nyssa aquatic and black gum: N. sylvatica), and cypress (Taxodiumspp.) and loblolly bay habitats, however, compared with slash pine (Pinus elliottii) or pine-oak (Quercus spp.), where bee yards usually were placed. The distributionof bearradiolocationslikely reflectedthe use of those swampand riparianareas,ratherthan avoidanceof bee yards. Distances to streamsfrom damagedbee yards (x = 1,750 m) were less than from undamagedyards (x = 4,442 m), and damagedbee yards were closer to unimprovedroads(x = 134 m) thanwere undamagedbee yards(x = 802 m). Ouranalysissuggests that bee yard placementaway from bear travelroutes (such as streamsand unimprovedroads) can reduce bear depredationproblems. Our results strongly indicate that working electric fences are effective deterrentsto bear damage to bee yards, even in areas frequentedby bears. A survey of beekeepers indicatedthatapiaristsoften relied on more expensive, less effective, and sometimesillegal methodsto protecttheir bee yards from bears. Beekeeperswithin bear range should be urged to considerelectric fencing, which can almost eliminatebear damage to their yards. Key words: American black bear, apiary, bees, damage, electric fencing, Florida, Georgia, habitat, Okefenokee, Ursus americanus Ursus16(2):234-244(2005)
Beekeeping is an importantindustry the US. More than 82 million kg of honey was produced in 2003, worth >$255 million (National AgriculturalStatistics Service 2004). Unfortunately,high quality bee range often coincides with black bear habitat; American
cause of damage to apiaries in North America (Huygens and Hayashi 1999). Damage is difficult to estimate, but losses to individual beekeepers can be economically devastating (Lord and Ambrose 1981, Maehr and Brady 1982, Jonker et al. 1998). It is, therefore, important to better understand bear behavior
black bears (Ursus americanus) are the most significant
relative to bee yards so that effective management techniques can be developed to reduce losses to apiarists.
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dations. Movement of Americanblack bears near bee yards has not been intensively studied, however, nor has the frequency with which bears encounterbee yards and factorsthat may lead to those encounters. Bears that raid properlyfenced bee yards in Georgia are most commonly relocated; killing depredating bears generally is not permitted.Relocation is sometimes perceived by beekeepers
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as ineffective and, consequently, has generated negative attitudes about managementagencies and black bears. Management agencies, on the other hand, want to address damage issues withoutcompromisingthe statusof the bearpopulation.Ourobjectiveswere to assess local landownerattitudestoward bears, evaluate movement of bears relative to bee yards, estimate the extent of losses to bears in an area with a high density of apiaries, and evaluate methods to reduce bear depredations.
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Our researchwas centeredat 30?40' north latitude and 82?30' west longitude, adjacentto the northwestportion 10 O of Okefenokee National Wildlife Refuge (ONWR) in Charlton,Clinch, and Fig. 1. Study area location and landscape characteristics along the Ware counties in southeast Georgia northwestern portion of Okefenokee NationalWildlifeRefuge, Georgia, (Fig. 1). Privatelands within the study 1995-99. area were predominatelypine plantations, managed by Jefferson Smurfit and ContainerCorporationand by RayonierIncorporatElectric fences have long been used to deter bears ed. Nearby huimanpopulationcenters were the cities of from bee yards (Storeret al. 1938) and are consideredto be the most effective method to protectapiaries(Maehr Waycross to tlhe north and Folkston to the east of the 1984, Huygens and Hayashi 1999). Other measures, study area. OkefenokeeSwamp lies within ONWR and is one of such as the use of aversive baits and on-site release of the largest fre;shwaterwetlands in the United States. trapped nuisance bears, have been used with varying Water input pirimarilyoccurs throughprecipitation,but success (Colvin 1975, Wooldridge 1976, Brady and Maehr 1982). Evaluationof the effectiveness of electric springs and stream runoff from higher lands to the fencing to deter bears has largely been anecdotal, northwestadd to the volume (Duever 1982). Soils in this region, formedIfrom marinesedimentsdepositedduring althoughHuygensand Hayashi(1999) performeda more the Pleistocenie and Holocene epochs, are typically rigorous assessment of Asiatic black bear (Ursus acidic and poc,r in nutrients(Cohen et al. 1984, Loftin thibetanus) depredation rates at fenced apiaries and et al. 2000). The vertebratediversity of this wetland crop fields in Japan.They documentedbearactivitynear no fences based on field sign but documented depresystem is greater than in any area of similar size in the Km
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southeasternUS; this is a result of the dynamic and complex landscape mosaic (Meyers and Odum 1991, Wigley and Lancia 1998) and because many species reachthe geographicallimit of theirrangesat or nearthe area (Laermet al. 1980). The climate in southernGeorgia is subtropical,characterized by cool, dry winters and hot, wet summers (Howell 1984). The average annualtemperaturefor the region is 20?C and ranges from an averageminimumof 13?C to an average maximum of 27?C (Henry et al. 1994). Wetland habitats of Okefenokee Swamp are comprised of pure to mixed stands of bay (red bay: Persea borbonia,loblolly bay: Gordonialasianthus,and southern magnolia: Magnolia virginia), gum (water tupelo:Nyssa aquatic and blackgum:N. sylvatica), and cypress (Taxodiumspp.), shrub swamps, prairies, and open water.The drieruplandareason the remoteislands and surroundingthe swamp basin are made up of forested pinelands interspersedwith smaller bayheads and cypress domes. The surroundingprivate lands are predominantlymanaged as industrialslash pine plantations on cutting rotationsof about 25 years. Prescribed fire is frequentand the understoryof those plantationsis primarilycomprisedof saw palmetto(Serenoa repens), wax myrtle (Myrica cerifera), and bitter gallberry(Ilex glabra). Dense vegetationthroughoutboth wetland and upland habitats affords bears nearly ubiquitousescape and restingcover. Blueberry(Vacciniumspp.) andhuckleberries(Gaylussaciaspp.) areprimaryspringfoods for bears at Okefenokee, followed by sweet gallberry(Ilex coriacea), saw palmettofruit, and grapes (Vitis spp.) in summer, and palmetto fruit, black gum, and acoms (Quercus spp.) in autumn (Dobey et al. 2005). Black gum and acorns are patchily distributed in wetland areas, whereas sweet gallberry,blueberry,huckleberry, grapes,and saw palmettoarewidespreadin uplandareas. In additionto wood products,honey is an important agriculturalcommodityof the region (NationalAgricultural Statistics Service 2004). Bee yards on our study area were located outside ONWR on privatelands. Bee yard plots were designatedand leased to beekeepersby corporatelandownerson a yearly basis.
Methods Capture and handling We capturedblackbearswith Aldrichspring-activated foot snares (Aldrich Animal Trap Company, Clallam Bay, Washington,USA) equippedwith automobilehood springs(Johnsonand Pelton 1980). Trappingtook place from early June throughlate September1995-98. Trap-
sites were generallyestablishedto completelysamplethe area and avoid large gaps in the sampling grid. Traps were set nearknown beartravelroutesandbearsign. We immobilizedcapturedbears with a 2:1 mixtureof ketamine hydrochloride(ketaset, Burns VeterinarySupply Incorporated,FarmersBranch, Texas, USA) and xylazine hydrochloride(rompun, Haver-LockhartIncorporated,Shawnee,Kansas,USA). Immobilizationdrugwas administeredwith a pushpole at a dosage intramuscularly of 4.4 mg of ketamine hydrochlorideand 2.2 mg of xylazine hydrochlorideper kg of estimatedbody mass. We monitoredbody temperature,pulse, and respiration throughouteach immobilization. We tattooeda permanentidentificationnumberon the insideupperlip or innerthighof each bear.Numberedear tags, correspondingto individual tattoo identification numbers,were placed in both ears of each bear. Each female bear estimatedto be > 1 year of age and a select number of male bears received radiocollars (Telonics Incorporated,Mesa, Arizona,USA and Lotek Engineering Incorporated,Ontario,Canada).We equipped each collar with a 12.5-cm wide x 0.4-cm thick leatherspacer that served as a breakawaydevice (Hellgrenet al. 1988). We extracteda first upper premolartooth for aging by cementumannulianalysis (Willey 1974). Tooth sectioning, staining, and age assignment were conducted by Matson Laboratories(Milltown, Montana, USA). At the conclusionof handlingeach bear,we administered yohimbine hydrochloride(Lloyd Laboratories,Shenandoah, Iowa, USA), an antagonistfor xylazine hydrochloride,throughthe sublingualvein at a dosage of 0.2 mg/kg of body mass. All trappingandhandlingactivitieswere in accordance with approved University of Tennessee Animal Careand Use Protocols(UT-ACUC#760). Radiotelemetry We estimated the location of radiocollared bears from the groundwith a Model TR-4 receiver (Telonics Incorporated,Mesa, Arizona, USA) and a 5-element, vehicular roof-mounted antenna (Wildlife Materials, Carbondale,Illinois, USA). Aeriallocationswere collected from a Cessna 172 fixed-wingaircraftwith a receiver and a toggle switch that enabledus to change reception between H-antennae (Telonics Incorporated)mounted to each wing strut. Telemetrylocations estimatedfrom the ground were determined by triangulationusing the loudest signal method (Springer 1979, Mech 1983). Bear locations were calculated from >3 azimuths that were between 45? and 135?apartand collected within 20 min. Ground telemetrydata were plotted on 1:24,000 US Geological Ursus 16(2):234-244 (2005)
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identical to those described above. Radio fixes were known by the recorder to be test collars but locations of those collars were not known. In additionto
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Study area boundary
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knownden sites into our telemetryerror analysis. In those cases, error was determinedby calculatingthe distance betweenthe actuallocationand the first recorded telemetry location when we presumedcollar loss or den emergence occurredbased on clustered sequential locations.Telemetryerrorwas obtained by calculatingthe distancebetween the estimatedlocation and the actual location, the latter determinedwith a GPS (Zimmermanand Powell 1995).
Spatial analysis We used the 95% fixed kernel Okefenokee National method (Worton 1989) to estimate Wildlife Refuge overall home ranges of bears. All 95% fixed kernel estimates were calculated using the Animal MovementExtension * a (Hooge and Eichenlaub 1997) to ArcView? GeographicInformationSystem (GIS, EnvironmentalSystems Research Institute, Redlands, California, USA). home ranges were calculated Overall Km for all bears with >40 radiolocations 60 0 (Seaman et al. 1999) that were monitored for >6 months during the active Fig. 2. Bee yard locations adjacent to the northwestern portion of season (late Apr to Dec). Okefenokee National Wildlife Refuge, Georgia, 1995-99. Study area To determine whether bear moveboundaries were delineated by buffering each bee yard with an arc with a radius equal to the average minimum distance between bee ments were associated with bee yards, yards (1,611 m). The outside periphery of those arcs represent the we identified all bee yards within the study area boundary. study area and determinedUTM coordinateswith a GPS. Bee yard locations were entered into ArcView? as a point coverage. Bear Survey (USGS) topographicmaps at the time of collection and subsequentlyrecordedas universal transverse telemetrylocations and home rangeswere overlaidwith Mercator (UTM) coordinates. Aerial locations were the bee yard coverage. obtained by flying increasingly smaller circles over We were interested in evaluating bear movements radiocollared bears until we presumed individuals to be only in the portion of the study area where bee yards directlyunderthe aircraft.Locationswere then recorded were present.Therefore,to restrictour analysis to areas near bee yards, we circumscribedeach bee yard with using a global positioning system (GPS; MagellanGPS a circle, the radius of which was equal to the average Systems, Osborne Park, Australia).All GPS locations were recordedas UTM coordinates. minimum distance between bee yards. Boundaries We estimatedtelemetryerrorby placing test collars in were defined by overlaying those circles around bee all habitat types that were used by bears. Test collars were yards and connectingthe outermostseries of arcs using located with groundand aerialtelemetryusing methods the BUFFER procedurein ArcView? GIS (Fig. 2). We _J_
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created 8 distance categories consisting of a series of 200-m wide bands surroundingeach bee yard, again using the BUFFER procedure.We then used compositional analysis (Aebischer et al. 1993) to determine whether some distance bands were disproportionately used by bears relative to availability within their respective home ranges (third-orderselection, Johnson 1980). Compositional analysis uses multivariateanalysis of variance to analyze use and availabilitydata in which variablesarerepresentedas proportions.The technique determines statistical significance of differences and the rankorderof differencesbetween the variables. Additionally,we established7 cover types based on a digital map layer (30- x 30-m resolution;FloridaGap Analysis Project,FloridaCooperativeFish and Wildlife Research Unit, University of Florida, Gainesville, Florida, USA): gum-bay-cypress, loblolly bay, pineoak, pine, swamp forest, shrubwetlands, and disturbed (Dobey et al. 2005; Table 1). Again, we restrictedour analyses to the area near bee yards. The disturbed classificationwas representedby open water, bare soil, and urban or agriculturallands; those classifications were pooled because they comprised
