Denning and Related Activities of Black Bears in the Coastal Plain of North Carolina1

DENNINGAND RELATEDACTIVITIES OF BLACKBEARS IN THE COASTALPLAIN OF NORTHCAROLINA1

ROBERT J. HAMILTON,School of Forest Resources, University of Georgia, Athens 30602 R. LARRY MARCHINTON,School of Forest Resources, University of Georgia, Athens 30602

Abstract: Black bear (Ursus americanus) activities in southeasternNorth Carolina were determinedby radiotelemetry,trapping success, track counts, scat collections, and hunterharvests from May 1974 to January1977. All data indicatedthat bear activity decreasedprogressively in autumn.The only significant wintermovement was by males, 3 years old and younger. Four bears dennedon the groundin dense Carolinabay vegetation. One adult female denned in a bald cypress (Taxodiumdistichum) with an entrancecavity approximately25 m above the water. The earliest date for denningby radio-monitoredbears was 5 December and latest emergence was 22 April. five bears remainedinactive for periods rangingfrom 85 to 113 days, averaging102. An adultmale had the shortestperiod of inactivity. Two subadultmales remainedactive throughout the midwinter. Postdenning movements graduallyincreased and reached a peak duringbreeding season in June and July.

Black bears are most often associated with moun- tainous areas of the western and easternUnited States, but there are also well-established populations in swampy areas throughout the Coastal Plain of the Southeast. A black bear study in the North Carolina Coastal Plain was conducted from May 1974 to January 1977. Information on behavior and ecology associated with denning in a relatively mild climate is presented in this paper. Our study is the first documentedreport of native black bears denning in the southeasterncoastal region. We are grateful to private landowners, personnel of the North Carolina Wildlife Resources Commission and Bladen Lakes State Forest, and to many friends and sportsmen for their cooperation and assistance throughoutthis study. STUDY AREA The study area, located in Bladen County, North Carolina, consisted of about 55,930 ha, including 13,051 ha in Bladen Lakes State forest (Fig. 1). Eleva- tion varies from 9 to 30 m above sea level, and local relief averages less than 1 percent fall over the 45- km-long study area. Annual rainfall averages approximately 135 cm and the growing season averages about 220 days per year. Snowfall is uncommon and did not occur duringthe study period. The climate is mild and pleasant with temperaturesseldom reaching 38 C in summer and below -12 C in winter. Fig. 1. Location of the 55,930-ha study area in Bladen County, North Carolina. Illustration shows 8 of the many Carolina bay lakes characteristic of this The largestsingle habitatcomponent (41 percent)was region. Carolinabays. These elliptical craterscommonly occur from north-central Georgia to southeastern North Carolina (Murray 1961:512-519). Bays contain ex- dense thickets of mat- 1Study supported by Federal Aid in Wildlife Restoration tremely evergreen woody plants Act, Project No. W-57, Job No. 6-B, and conducted under ted with laurel-leaf greenbrier(Smilax laurifolia) and the auspices of the North Carolina Wildlife Resources Com- related species. The name bay apparentlywas derived mission and North Carolina State University, Raleigh; from the trees Gordonia School of Forest Resources, Institute of Natural Resources, bay (e.g., loblolly bay, and Agricultural Experiment Station of the University of lasianthus; sweet bay, Magnolia virginiana; and red- Athens. Georgia, bay, Persea borbonia) frequently scatteredthroughout 122 BEARS- THEIR BIOLOGY AND MANAGEMENT the oval depressions(Johnson 1944:1). Other common (Etorphine) injected intramuscularlyby a dart from a trees were red maple (Acer rubrum), white cedar CO2-powered gun. The antidote used was M50-50 (Chamaecyparis thyoides), and pond pine (Pinus (Diprenorhine). Each bear was ear-tagged, lip- serotina). The shrub layer grew from a peat bog floor tattooed, weighed, and measured. An upper first pre- and contained fetterbush (Lyonia lucida) and various molar was extractedfor age determinationby counts of berry-producingshrubs such as huckleberries(Gaylus- tooth cementum layers (Stonebergand Jonkel 1966). sacia spp.), sweet gallberry (Ilex coriacea), winter- Selected animals were fitted with collars containing berry (I. verticillata), and blueberries (Vaccinium radio transmitterswith a frequency range of 150.850- spp.). Occurringin associationwith bays and having an 151.125 MHz. Radio-taggedbears were located daily, elliptical shape, bay lakes covered 3 percentof the area if possible, by triangulationwith a 12-channelreceiver (Fig. 1). and directional 4-element, hand-held yagi antenna. Ridges of fine-grained, sandy loam soals, constitut- Sudden changes in location or movement into an inac- ing 33 percent of the study area, partially surrounded cessible area often resulted in unsuccessful attemptsto the bays. These sand ridges were dominated by long- locate bears from the ground. A Piper Supercubwith a leaf pine (Pinus palustris) and scrub oaks (Quercus 4-element yagi antenna attached to a wing strut was spp.). Persimmon trees (Diospyros virginiana) were invaluable in locating "missing" bears. Seasonal ac- common. Shrubs such as small gallberry(Ilex glabra), tivity patterns, habitat preferences, and range sizes wax myrtle (Myrica crifera), and blackberry(Rubus were determinedby repeatedlyradiotracking individual cuneifolius) were sparse. Ground story vegetation in- bears during 24-hour periods. cluded clumps of legumes (e.g., Baptisia sp., Lupinus A 55-km track census route was traveled 1-3 times spp.) and grasses (e.g., Aristida stricta, Panicum spp., each month for 2 years as an aid in determiningsea- Sporobolus spp.). sonal activity patterns. Weather permitting, track Colly Creek and an 8,000-ha swamp system, over 2 counts were conducted at least 3 days after a rain. The km wide in places, comprising 14 percent of the study numberof tracks observed was divided by the number area, bisected the area. A dense canopy formed by red of 24-hourperiods since the last rain. Results expressed maple, yellow popular (Liriodendron tulipifera), in tracks/track-nightgave an overall view of monthly blackgum (Nyssa sylvatica), red bay, and bald cypress activity. Scats were collected daily throughout the shaded such common shrubs as pepperbush(Clethra study period and the monthly totals were used to indi- alnifolia), titi (Cyrilla racemiflora), and fetterbush. cate activity patterns. Data were collected from legal Greenbriervines were common and usually occurred harvests during 3 bear-huntingseasons to gain insight with patches of shrubs. The organic, black, mucky into sex ratio, age structure, and population density. loam soil was covered by decaying plant matteron sites Changing sex ratio and age structurethroughout each above water, while some openings, associated with hunting season were used to estimate vulnerabilityre- timberharvests on wet sites, supportedstands of emer- sulting from differentialactivity patternsbetween sexes gents. and between age-classes (adults, >3 years old; sub- Residential areas (2 percent) and farmlands(7 per- adults, <3 years old). of the area. cent) composed the remainder study Major RESULTS crops produced were corn, soybeans, and blueberries. Twenty-one differentbears were captured38 times. Approximately45 percent of the private land (42,600 Ten animals (6 males, 4 females) were selected for ha) was owned by timber companies practicing short- radio-monitoring.Seasonal activity patterns and den- rotation even-age management with clearcutting fol- ning behavior were determinedby daily locations and lowed by replantingof slash pine (Pinus elliottii). Dur- by monitoring individual bears during 68 complete ing a 20-yearspan from the mid-1930s to the mid-1950s, 24-hour periods. Telemetry provided information on sawtimberwas harvested from the Colly Swamp sys- the activities of animals whereas suc- tem. specific trapping cess, monthly track counts, scat collections, and har- served as indicatorsof activities at the METHODS vest data population level. Bears were capturedin box-type trapsconstructed of a metal framecovered with chain-linkwire. Traps were Winter Inactivity permanentlymounted on trailers to aid in transporta- The scarcity of tracks and scats indicated that most tion. All capturedbears were immobilized with M99 bears were inactive during the winter (Fig. 2). No DENNINGAND RELATED ACTIVITIES* Hamilton and Marchinton 1123

- SCAT COLLECTIONS Three adult females began denning between 5 De- - -- TRACKS/TRACK-NIGHT cember and 21 December. An adult male became inactive by 28 December and a young female bedded down 0 for the winteron 3 January.Two young males (2 and 3 u years old), tracked for only short periods during mid- .. 0 winter (6 January- 28 January, and 15 January- 9 February 1976, respectively), remained active during those periods. None of the 4 females were lactatingor z accompaniedby cubs when trapped, and there was no evidence that any bore cubs during the radio tracking

FALL WINTER SPRING SUMMER period. (O-N-D) (J-F-M) (A-M-J) (J-A-S)

Fig. 2. Predenning, denning, and postdenning activity indicated by track count Den Site Selection and Related Activity and scat collection data compiled on a season basis for a 2-year period. No movement by denningbears was detected during trackswere observedon the regularcensus route during any of 41 complete 24-hour monitoringperiods, indi- winter although several small tracks (apparentlythose cating that bears rarely ventured from their den sites of young bears) were found in other parts of the study duringthe day or night. Several bears were forced from area. Three subadultmales were the only bears trapped their dens for shortperiods in midwinter, apparentlyby from Januarythrough March during both winters. rising water or other disturbances.An adult male (No. The 3 bears radio-monitoredthrough the winter of 8), located in a 1,040-ha bay, vacated his den on 17 1974-75 and 2 of the 4 monitoredthe next winter re- February 1975 after several days of heavy rain. He mained inactive for extended periods despite relatively returnedto the same location on 21 February and re- mild temperatures(Fig. 3). The earliest date for den- mained there until 23 March 1975. In late January ning of radio-tagged bears was 5 December and the 1976, the same conditions evidently caused a 22-year- latest emergence was 22 April. Periods of inactivity old female (No. 33) to leave her den site in a 115-ha ranged from 85 to 113 days, averaging 102 (Fig. 3). bay. Two days later, she settled in the northwesternend

BEAR AGE WINTER NO, SEX (YEARS) INACTIVE PERIOD No. DAYS DEN SITE 1974-75 7 F 3 1 110 BAY 1974-75 19 F 6 i .-. 113a BAY 1974-75 8 M 8 -- 85 BAY

1975-76 33 F 22 106 BAY

1975-76 45 F 6 - -96 HOLLOWTREE l l l~~~~~~

DEC JAN FEB MAR APR I I I I 1974-75 9.06 10,45 10.89 12.61 16.17

1975-76 7.95 6.39 12,72 15,61 17,61

AVERAGEMONTHLY TEMPERATURE (?C) aSIGNAL LOST27 MARCH1975

bDEN SITE OBSERVED

Fig. 3. Periods of inactivity of 5 radio-monitored black bears and relatively mild average monthly temperatures in Bladen County, North Carolina, during the winters of 1974-76. Temperatures were recorded at the U.S. Army Corps of Engineers Lock and Dam No. 2 on the Cape Fear River approximately 16 km from our study area. 124 BEARS- THEIR BIOLOGY AND MANAGEMENT

of the same bay, 966 m from the original den site, and Carolina bays, because the bays have homogeneous remained inactive until 29 March 1976. vegetation and terrainand lack large trees or logs. A 6-year-old female (No. 45) began denning in a A fecal plug expelled as the bearfled was darkgreen 4-ha bay on 21 December 1975. Disturbanceby a pack and encased in a sheathof mucus. It weighed 139 g and of deer dogs on 1 January 1976 apparentlymade her measured approximately10 cm long. Contents of the move into nearbyColly Swamp, where she was found plug measuredby volume included leaves of fetterbush in a hollow bald cypress tree on 3 January.The den tree (53.8 percent)and laurel-leafgreenbrier (46.1 percent). measured 1.1 m in diameterabove the butt swell, was Occuringin trace amounts(<0.1 percentvolume) were approximately 37 m tall, and was surrounded by sericea lespedeza (Lespedeza cuneata), pokeberry standingwater 1 m deep. The base was not hollow and (Phytolacca americana) seeds, intestinal lining, and the cavity entrance was about 25 m above the water. unidentifieddead leaves and stems. Telemetric signals indicatedthat the bear was no more than a few meters below the cavity entrance. She re- and moved her collar on 9 April 1976, 2 weeks after leav- Predenning Postdenning Activity ing the den tree. Telemetric data suggested a steady decrease in ac- A 6-year-old female (No. 19), located in a 910-ha tivity during autumn, prior to denning, and a gradual bay, moved 332 m when an unsuccessful attemptwas increase in movements during the spring after leaving made to find her den. She was still at a "new" location the den. These trendsare shown by the numberof days in the same bay when her radio transmitterceased an individual bear was radio-located relative to the functioning on 27 March 1975. number of different positions mapped for that bear On 12 March 1975, we examined the den of a 3- during each month (Table 1). Excluding the winter year-old female (No. 7). Vegetation in the 36-ha bay period of inactivity (late December through March), was very dense and we used a macheteto open a trail to movement was detected at some time during all 24- her location. This disturbancecaused her to withdraw hour monitoring periods except 1 occurring in late when we approachedwithin 15 m. She returnedshortly November and 2 in mid-December. thereafterand did not leave again until 22 April 1975. Monthly trackcounts and scat collections were com- This animal's "den" was a shallow depression piled by season for the study period. Movement de- measuring61 cm x 56 cm with an 11-cm rim of litter creasedprior to winterinactivity and graduallyincreased and was located at the base of a pond pine approxi- during spring, peaking during the breeding season in mately 10 m tall. Bedding materialconsisted of pond June and July (Fig. 2). The combination of limited pine needles and leaves from surroundingfetterbushes. activity and increased use of bait piles during autumn Insteadof using a site with a protectivecanopy of veg- facilitated collection of scats. In spring and summer, etation, as may have been expected, the female had bears ranged more widely and preferredthe abundant removed the overheadfetterbush branches evidently by natural foods; therefore, scats were not concentrated clipping them with her teeth. This open-groundnest is aroundbait piles-especially during the breeding sea- assumed to be representativeof the dens located in son.

Table 1. Monthly activity of radio-equipped bears from 1974 to 1976 as indicated by dividing the number of days they had changed locations by the total daily locations determined each month and expressed as a percentage.

Month Bear Age no. Sex (years) Oct Nov Dec Jan Feb Mar Apr May June

8 M 8 100 100 100 0 13 30 100 100 100 7 F 3 68a 83 75 80 0 4C 35 87 92 45 F 6 26 10c 0 16 66 33 F 22 94 44 10 7b 0 12C 70 100 19 F 6 75 14 0 80 46 49 M, 2 92 31 M 3 100 100 aBear was wounded by a hunter and remained in one location from 17 October to 24 October 1974. Movement resulted from excessive rainfall. 'Movement resulted from human disturbance. DENNINGAND RELATED ACTIVITIES* Hamilton and Marchinton 125

North Carolina has a split hunting season for bears. and above-averageprecipitation but that good physical In 1974-75 and 1975-76, the seasons were mid-October condition was an ultimateprerequisite to denning. Car- through mid-November and mid-December through 1 penter (1973) reportedthat bears low in storedbody fat January. The 1976-77 seasons were 1-20 November often remained active throughoutthe winter. and 13 December-1 January. Bladen County had a Bears in our study area were not subjectedto extreme known kill of 44 bears (27 males, 16 females, and 1 weather conditions prior to denning. Although food unknown) for this 3-year period. The percentage of availabilitydecreased markedlyas autumnprogressed, adults, particularly females, in the total harvest de- most bears in our area apparentlywere able to build creased from October through December. These data adequatefat reserves before entering dens. There was suggest a trend toward decreased activity, especially evidence, however, that subadultmales may not den at among adult females, during autumn. The common all. This failureto den may have been relatedto low fat hunting practice is to search for bear sign along dirt reserves in this age-class, as subadultsharvested in late roads and aroundbait piles and then select the largest autumngenerally had less fat than older bears. track on which to release dogs. This procedure may Adult females and subadultbears of both sexes usu- result in a disproportionatelyhigh harvest of adults ally den earlier than adult males (Erickson et al. 1964, during early autumn. Adults and subadults probably Lindzey and Meslow 1976). Jonkel and Cowan (1971) exhibited similar movement patterns during the early found adult males emerging from dens before sub- season, but subadults, particularlymales, apparently adults, but Lindzey and Meslow (1976) reportedthat remainedmore active and were more vulnerableto har- adult males and 2-year-olds of both sexes emerged at vest late in the hunting season. approximately the same time, followed by adult females. In our study, females denned earlier and remained inactive later than males. DISCUSSION Black bears use a variety of den sites throughout their range (e.g., Erickson et al. 1964:100). Females of the black bear to a of habitats Adaptation diversity and yearlings have been found to select sites offering throughoutthe United States and Canada is due par- better protection from weather than do adult males tially to its ability to become dormantduring winter, a (Cahalane 1947, Erickson et al. 1964). Protected sites of period harsh weather and minimal food supply. In may not always be selected, however, as several au- the northern reaches of the bear's its annual range, thorities reported finding females with cubs in open consists of for winter dor- activity cycle preparing nests, or depressionsin thickets, or underthe boughs of for to 6 months mancy, denning periods up (Erickson coniferous trees when the ground was covered with Hatler Jonkel 1965, 1967, and Cowan 1971), and re- snow (Morse 1937, Smith 1946, Cahalane 1947). As from the cuperating dormancy. Moving southward, mentioned, 4 bears radio-monitoredduring our study of decreases to less than 3 period dormancy usually selected den sites in Carolinabays. These densely veg- months as winter weatherbecomes more moderateand etated bays appeared to provide adequate protection, the durationof available food increases. Duffy (1971) except after extended periods of rainfall. The bear that that native bears in Louisiana remained suggested ac- selected a hollow tree was the only one known to den tive whereas those from during winter, transplanted outside a bay. Suitabletrees for denningwere scarce on Minnesota denned for extended periods. the study area as most of the large trees we examined Most studies concerning factors that elicit denning were hollow to the ground and contained swamp water have been conducted in regions with severe winters. during winter. Eight such trees (7 bald cypress, 1 Winter weather conditions, particularlysnowfall, were blackgum)bore signs of having been climbed by bears, reported to have induced denning of bears in Ontario an indicationthat they were examined and found to be (Northcott and Elsey 1971) and Montana (Jonkel and unsuitablefor denning. Cowan 1971). Decreased food availabilityand physical Attemptsto observe bears in bay den sites resultedin condition are also importantfactors (Erickson 1965, bears leaving before visual contact was made. The ex- Carpenter1973). Lindzey and Meslow (1976) studied periences of Poelker and Hartwell (1973:74) and black bears during the dormantperiod in southwestern Lindzey and Meslow (1976:411) in southwestern Washington, an area of mild winters. They concluded Washingtonindicated that bears, except most females that the stimulus for bears proximal to enter dens was with newborn cubs, left their dens as humans ap- providedby the cumulativeeffects of low temperatures proached. However, accounts of bears observed in 126 BEARS -THEIR BIOLOGYAND MANAGEMENT

dens are common in the literature (Morse 1937, dormancy,and graduallyincreased in springafter bears Schoonmaker1938, Matson 1954, Duffy 1971, Jonkel emergedfrom dens. These trendshave been reportedin and Cowan 1971). a number of other studies (Jonkel and Cowan 1971, Fecal plugs such as the one found during our study Hardy 1974, Amstrup and Beecham 1976, Lindzey have been reported commonly (Morse 1937, Smith and Meslow 1976). 1946, Matson 1954, Svihla and Bowman 1954), but a quantitativeanalysis of the contents has not been previ- MANAGEMENTRECOMMENDATIONS ously reported. Smith (1946) described the accumu- Black bears in the North Carolina Coastal Plain related residue in the lower colon as a heterogeneous quire a diversity of habitattypes. One of the most im- collection of material picked up at random, after the portanthabitat components is that which provides the suspension of active feeding in fall, together with a necessary protection during winter dormancy, a par- residue of secretions. Conversely, it appearsthat bear ticulary critical period when females are rearing cubs. No. 7, a 3-year-old female, "selected" the leaves of Large, relatively impenetrableCarolina bays on our greenbrierand fetterbushthat comprised 99.9 percent study area served this purpose; however, we feel that volume of the fecal plug we found in March 1975. bears would have used tree activities almost exclu- Greenbriarleaves were not considered a major food sively, if available, because of the added protection item, especially duringwinter, but were most prevalent from weather, high water, man, and hunting dogs. in scats collected in May; leaves of fetterbushdid not Most of the large trees were removed by extensive occur in any of the 732 scats collected duringour study logging in the past. Now, vast acreages of bay habitat (unpublisheddata). are being convertedto farmland.If black bearsare to be All of our radiotelemetric,track count, scat collec- maintainedin viable numbersand hunted as game ani- tion, and harvestdata indicated that activities decreased mals in eastern North Carolina, their existing habitat progressively in autumn as bears preparedfor winter must be preserved.

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