Fleming & Heithaus, 1986. Seasonal Foraging Behavior of the Frugivorous Bat Carollia Perspicillata

8/2/2019 Fleming & Heithaus, 1986. Seasonal Foraging Behavior of the Frugivorous Bat Carollia Perspicillata

1/13

American Society of Mammalogists

Seasonal Foraging Behavior of the Frugivorous Bat Carollia perspicillataAuthor(s): Theodore H. Fleming and E. Raymond HeithausSource: Journal of Mammalogy, Vol. 67, No. 4 (Nov., 1986), pp. 660-671Published by: American Society of MammalogistsStable URL: http://www.jstor.org/stable/1381127

Accessed: 18/05/2010 07:51

Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at

http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless

you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you

may use content in the JSTOR archive only for your personal, non-commercial use.

Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at

http://www.jstor.org/action/showPublisher?publisherCode=asm.

Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed

page of such transmission.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of

content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms

of scholarship. For more information about JSTOR, please contact [email protected].

American Society of Mammalogists is collaborating with JSTOR to digitize, preserve and extend access to

Journal of Mammalogy.

http://www.jstor.org
http://www.jstor.org/stable/1381127?origin=JSTOR-pdfhttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/action/showPublisher?publisherCode=asmhttp://www.jstor.org/action/showPublisher?publisherCode=asmhttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/stable/1381127?origin=JSTOR-pdf


2/13

SEASONAL FORAGING BEHAVIOR OF THE FRUGIVOROUS BATCAROLLIAPERSPICILLATA

THEODORE H. FLEMING AND E. RAYMONDHEITHAUSDepartment of Biology, University of Miami, Coral Gables, FL 33124 (THF)Department of Biology, Kenyon College, Gambier, OH 43022 (ERH)

ABSTRACT.-We studied the foraging behavior of the frugivorous bat Carollia perspicillata(Phyllostomidae)during two dry seasons and two wet seasonsin northwesternCosta Rica usingradio-telemetryand capture-recapturetechniques. Seasonalchanges occur in both quantitativeand qualitative aspects of this bat's foraging behavior, primarily as a result of changes in thedensity and distribution of food. Compared to bats in the wet season, bats fly greater distancesto harvest fruit, are concentrated in fewer resource patches, change general feeding locationsmore frequently,and are more sensitive to moonlightconditionsin the dry season.In both seasons,bats show high short-termfidelity to the 2-3 feeding areas they visit each night. Food distribu-tions,predatorrisk, and, in males, social status,influencethe foragingbehaviorof C. perspicillata.

The foraging behavior of many bats changes seasonally. Seasonal changes in types of preyeaten, night roosting behavior, and intensity of foraging effort are ubiquitous in temperate zonehibernating species (Anthony and Kunz, 1977; Anthony et al., 1981; Barclay, 1982; Davis andHitchcock, 1965; Erkert, 1982; Humphrey et al., 1977; Kunz, 1974; O'Shea and Vaughan, 1977;Stebbings, 1968; Tuttle, 1976). In tropical bats, seasonal changes are known to occur in thefollowing foraging parameters: diet breadth and type of food, patterns of habitat use, defenseof feeding areas, foraging group size, and migratory behavior (Barclay, 1985; Bonaccorso, 1979;Bradbury, 1977; Bradbury and Vehrencamp, 1976; Fenton et al., 1985; Fenton et al., 1977;Heithaus et al., 1975; Lemke, 1984; Start and Marshall, 1976; Thomas, 1983; Thomas andFenton, 1978; Vaughan, 1976; Whitaker and Black, 1976). All or most of these behavioralchanges ostensibly reflect seasonal changes in climate and the availability of suitable food items.In this paper we examine seasonal changes in the foraging behavior of the common neotropicalfrugivorous bat, Carollia perspicillata (Phyllostomidae), by addressing the following questions:(1) Are there qualitative or quantitative seasonal differences in the foraging behavior of C.perspicillata? (2) Within seasons, do significant year-to-year changes occur in its foraging be-havior? (3) What is the relative importance of food distribution, predation risk, and social statusas factors affecting its foraging behavior? To answer these questions we studied the foragingbehavior of C. perspicillata during two dry seasons in northwestern Costa Rica and comparedour results with those of a similar study conducted during two wet seasons at the same site(Heithaus and Fleming, 1978).

STUDYAREAANDMETHODSThis study was conducted in Parque Nacional Santa Rosa, GuanacasteProvince, Costa Rica, from mid-January to mid-to-late March in 1977 and 1978. The study area lies in the Tropical Premontane MoistForest life zone (Holdridge, 1967) at an elevation of about 300 m. SantaRosaconsistsof a mosaic of forestpatches of varioussuccessionalstages and fire-maintainedgrasslands; ts vegetation is described in detail byHartshorn(1983). In upland partsof the park where we worked, seasonally-deciduous ropicaldry forest isthe majorhabitat. Widely scattered patches of evergreen forest occur in moist ravines in the uplands andare more extensive in the park's lowlands. Rainfall is highly seasonal and virtually all of the annual total(about 1,600 mm) falls between early May and mid-November. Our study was conducted at the height ofthe dry season when most tree species were leafless. Our previous study was conducted in June throughAugust of 1975 and 1976 during the first half of the wet season after the forest canopy had completelyleafed out.We used radiotelemetry to study the foraging movements of 26 individuals of C. perspicillata, 12 (11males and one female) in 1977 and 14 (10 males, four females) in 1978. None of the females was repro-ductively active. These individuals were capturedin mist nets as they left the SenderoCave justafter sunset

J. Mamm., 67(4):660-671, 1986 660


3/13

FLEMING AND HEITHAUS-FORAGING OF CAROLLIA

(see Heithaus and Fleming, 1978). The weights of radio-tagged bats ranged from 18.5 to 21.5 g in 1977and from 17.0 to 24.0 g in 1978. We attached an AVM-SM1 transmitter equipped with a battery andantenna (2 g total weight) to the back of each bat with Silasticmedical adhesive. Transmittersremained onthese bats for an average of 11.7 days (range = 4-19 days) in 1977 and 10.6 days (range = 5-22 days) in1978. We tracked the bats using triangulationand other techniques as described in Heithaus and Fleming(1978) for 4-5 h on an average of 10.4 nights (range = 3-18 nights) and 7.8 nights (range = 3-17 nights)in 1977 and 1978, respectively.To determine the relative densities of bats in various areas away from the roost and to obtain dietaryinformation(Heithauset al., 1975), we captured bats in mist nets, collected fecal samples, and banded themon one forearm with a numbered plastic band (A. C. Hughes, Ltd., Hampton Hill, England). In 1977 wedusted 38 individuals with a cube of pollen gel (Beattie, 1971) and examined the melted gel under acompound microscope for evidence of flower visitation. Stashko(1982) similarly dusted 76 individuals forpollen in 1978.Additional data that are relevant to this comparisonhave been collected since 1978. These studies includeradio-tracking 40 bats during the summers of 1980 and 1981, studies of the social organization of C.perspicillata in 1980 and 1981, and a year-long capture-recaptureand plant phenology study in 1983 and1984. Detailed results of these studies have appeared (Williams, 1986) or will appear elsewhere.Whenever possible, we used the methods of Heithaus and Fleming (1978) to summarize and analyze ourradio-trackingdata. Our goal was to determine as precisely as possible the following foraging parameters:(1) number and location of each bat's feeding areas(hereafterabbreviatedas FAs),which we have previouslydefined as any area in which a bat remains for at least 30 min; (2) rates of movements between FAs; (3)night-to-night consistency in the use of FAs;and (4) total distance flown each night. We often had difficultyin measuring these parametersprecisely, because compared with individuals in our wet season study, batsgenerally were a long distance (>1 km) from our receiving stations. Together with our measured errormargin of 5-6% in accurately determining the known locations of transmitters, ong distance triangulationscaused our data plots of feeding locations to be spread out over a greater area than was the case with thewet season data. Our dry season triangulationdata, therefore, sometimes made it difficult to resolve nearbyFAs and to quantify rates of movements between them.

Owing to seasonal differences in resolution,we have attempted to be conservative in the identification ofspatially-distinctactivity areas (i.e., FAs). For the 1977 data, Fleming used a combination of field plots oftriangulationdata made the day after a tracking session and computer-drawn maps to define the locationsof FAs. Heithaus worked with hand-drawnmaps after the 1978 field season. We identified FAs on the basisof two criteria:(1) a reasonably tight cluster of points, and (2) repeated visits to these areas on two or morenights. We ignored outlying points and small clusters of points that appeared only on one tracking night ifthere were multiple-night clustersnearby on the assumptionthat these points were "noise"in the data. Todetermine distances between FAs and the roost, we measured from the center of each cluster of points tothe center of other FAs or to the roost. Because bats often did not fly in a straightline between FAs and toand from the roost,these measurementsmust be considered minimum estimates of the distancesbats actuallyflew.

RESULTSFood Habits and Food Availability

Our previous work in GuanacasteProvince (Heithaus et al., 1975) indicated that C. perspicil-lata eats fruit and visits flowersfor nectar in the dry season,whereas it is exclusively frugivorous(and, to a minor extent, insectivorous)in the wet season. Our early wet season food habit dataat Santa Rosa (Heithaus and Fleming, 1978) indicate that the bulk of its diet comes from fruitsproducedby the shrubspecies (Piperamalago, P. pseudo-fuligineum, and P. jacquemontianumand fruits of the tree species Muntingia calabura, Cecropia peltata, and Chlorophoratinctoria.With the exception of P. jacquemontianum, which is restricted to patches of evergreen forest(Fleming, 1985), each of these species is common, but patchily-distributed, in deciduous andevergreen forests. Estimates of the nightly ripe fruit biomass of these species in the wet seasonrange from 12 to 45 kg per ha in suitable habitats (Heithaus and Fleming, 1978).

In the dry season at Santa Rosa, C. perspicillata is mainly frugivorousbut occasionally visitsflowersof two species of canopy trees. Characteristicsof its dry season diet are summarized in

November 986 661


4/13

JOURNALOF MAMMALOGY

TABLE 1.-Summary of general characteristics of the diet of Carollia perspicillatain the dry season.Sources of data include Fleming (1985), Heithaus and Fleming (1978), and Stashko(1982).Generalimportance Habitat' and densityFamily and species in diet Period available (no. plants per ha)

A. Fruit speciesPiperaceae

Piper marginatum Major Jan-Feb D, E (100-300)P. amalago Minor Feb-March D, E (100-200)P. jacquemontianum Major March-April E (100-200)P. tuberculatum Minor April-May R (low)Elaeocarpaceae

Muntingia calabura Major Feb-July D, E (10-500)Moraceae

Cecropiapeltata Minor April-Oct D, E, R (5-100)LeguminosaeAcacia collinsii Major March-May D, E (20-300)

RhamnaceaeKarwinskiacalderoni Major Jan-Feb D, R (1-2)

MelastomataceaeClidemia octona Major? Jan-March E (low)

ChrysobalanaceaeLicania arborea Minor March D (3-4)

GuttiferaeVismia baccifera Minor April-May E (low)B. Flower Species

BombacaceaeBombacopsis quinatum Minor Jan-Feb D (common)Ceibapentandra Minor Jan-March D (rare)aHabitat abbreviationsare: D = deciduous forest, E = evergreen forest, R = riparianforest.

Table 1. With the exception of P. jacquemontianum, none of its wet season fruits are majorcomponents of its dry season diet. Compared with wet season fruits, species eaten in the dryseason tend to have shorterfruiting periods (which leads to higher turnover rates in month-to-month diet composition in the dry season than in the wet season), and many of them arerestricted in distribution to moist habitats (i.e., evergreen or riparian forests). Only Acaciacollinsii and Piper marginatum are common plants in deciduous habitats. Nightly biomass ofripe fruits (


5/13

TABLE 2.-Summary of the foraging behavior of Carollia perspicillata in four seasons. The 1975-76 data conoted, values are means and ranges (in parentheses).Parameter 1975-76 (wet) 1

Consistencyof roost use (proportion) 0.86 0.6Total known feeding areas (=FAs) 4.1 (2-6) 4.2Number of FAs visited per night 2.2 (0.33)a 2.1Distance from cave to FAs (km) 0.94 (0.1-3.2) 1.4Nightly FA overlap, within individuals 0.70 (0.19)b 0.6FA overlap between individuals 0.0025 0.3Distance between an individual's FAs (km) 0.65 (0.14)p 1.3Rate of movement between FAs (no. moves/h) 0.65 (0.46-0.82)a 0.71Minimum distance flown/night (km) 7.24 12.

a95% confidence limit of items.bStandarddeviation.* Subjectiveestimate (see Fig. 2).


6/13

JOURNALOF MAMMALOGY

FIG. .-Map of the locations f feedingareasof radio-taggedats n 1977.Location f the Sendero oostis indicatedby the solidtriangle.Uppercase letters ignify he feedingareasof different ndividuals. hestippled reasarepatchesof forest;bareareasareabandoned astures.

Foraging BehaviorA quantitative summary of the foraging behavior of C. perspicillata based on four seasons(two wet and two dry seasons)of fieldwork is presented in Table 2. We discussthese data andour qualitative observationsbelow.Consistency of roost use.-Individuals are highly faithful to a single day roost (i.e., theSendero Cave) in both wet and dry seasons. The probability of an individual returning to theSendero Cave each morning ranged from 0.69 (72/105 bat-mornings)in the 1977 dry season to0.86 in the wet seasons of 1975 and 1976 (Table 2). The failure of some individuals to returnto their regular day roost probably reflects a responseto the trauma of being radio-tagged. In

Vol. 67, No. 464


7/13


FIG. 2.-Map of the locations of feeding areasof radio-tagged bats in 1978. Upper case letters signify thefeeding areas of different individuals. Other symbols as in Fig. 1.

each field season, a few individuals temporarily moved to an alternate roost for a few daysimmediately after being radio-tagged. Most of these bats eventually returned to the SenderoCave.Number and locations of individual feeding areas. Regardless of season, bats visited fromone to eight different FAs during their tracking tenure. On a given night, individuals visited,on average, two or three of these FAs. Bats had visited a majority (90%and 72%in 1977 and1978, respectively) of their known FAs by their third tracking night in the dry season just asthey had in the wet season (Heithaus and Fleming, 1978). There were no obvious seasonaldifferences in total number of known FAs or number of FAs visited per night (Table 2).The general locations of FAs changed seasonally to some extent. In the wet season, most bats

November 1986 665


8/13

JOURNALOF MAMMALOGY

living in the Sendero roost foraged in deciduous forest north of the roost;a minority of individ-uals (ca. 20%of all wet season individuals we have tracked) foraged either east or south of theroost (Heithaus and Fleming, 1978 and more recent data). In the 1977 dry season, in contrast,most individuals foraged northwest or south of the Senderoroost (Fig. 1). Prior to 15 February,most (20/21) known FAs were north or northwest of the roost;after 15 February,most (15/19)of the known FAs were located south of the roost. The location of the 1978 FAs more closelyresembled the distributionof wet season FAs in that most individuals foraged either north orsouth of the roost (Fig. 2). No strong intra-seasonal hift in foraging locations occurred in 1978.A higher proportion (58%,n = 26) of Sendero individuals foraged south of the roost, oftenoutside the parkboundaries,in the dry season than in the wet season (x2 = 9.19, d.f. = 1, P


9/13


Fleming, 1978). Since we rarely tracked individuals continuously for entire nights, we cannotpresent actual data on flight distances. Instead, we rely on average values of tracked individualsto estimate the (minimum) distance flown by bats each night; most of the values needed forthese calculations are shown in Table 2.

Nightly flight distance was calculated as 2C + DbFA + DWFAn which C = mean commutedistance (i.e., average distance between the roost and all FAs), DbFA = distance flown betweenFAs, and DWFA= distance flown within FAs as bats harvest fruit and carry them to a night roost(see Heithaus and Fleming, 1978). DbFAwas calculated as 7(RbFA)(MbFA) in which 7 representsan estimate (based on evening and morning tracking sessions of the same bat) of the averagetime (in hours)that a bat spends away from its day roost,RbFA= the rate of movement betweenFAs, and MbFAs the mean distance between FAs (Table 2). The calculation of DWFAas basedon the harvest of 30 fruits (bats harvest more fruits than this when eating Piper and less fruitswhen they eat Chlorophoraor Cecropia fruits) times a flight distance of 80 m between nightroost and fruit source in the wet season and 100 m in the dry season (see below, Return to dayroost).Resultsof these calculations (Table 2) indicate that an "average"bat usually flies a minimumof about 7-8 km per night. Nightly flight distancesin 1977 were nearly twice this value becauseof the longer commute distances and greater distances between FAs. The proportionalcontri-bution of the major components of flight varied relatively little between seasons and years andaveraged 19.8%(commutes), 44.6% (moves between FAs), and 32.6% (harvesting fruit withinFAs).As previously noted, these calculations are minimum estimates of actual flight distances be-cause they are based on straightline measurements between destinations. The actual distancesflown while commuting or moving between FAs were often longer than this because bats usuallyavoided flying over open grasslandand instead traveled through forest when changing sites. Asecond reason why our calculations minimize flight distances, especially in the dry season, isthat some batsoccasionallyused the Sendero Cave as a night roost.In the wet season,only haremmales and other individuals feeding close to the cave used the day roost as their night roost(Heithaus and Fleming, 1978; Williams, 1986). In contrast, a greater number of individuals,including those feeding > 1 km from the cave sometimes returned to the cave between feedingbouts during the dry season. In 1977, four of 12 bats made relatively long-distance moves backto the cave on 13 occasions. In 1978, six of eight individuals made similar moves on 23 out ofa possible 44 nights. These returns to the day roost greatly elevate the total distance that batsfly when they are harvesting fruit in the dry season. If these longer moves had been fullyaccounted for in calculations of total flight distances in 1977 and 1978 (Table 2), dry seasonflight distances would certainly exceed those in the wet season,and the proportionof total flightrepresented by travel between fruit sourcesand night roostswould be higher in the dry than inthe wet season.

Exploratoryflights and rates of change of FA locations.-Because the locations of suitablefeeding sites change through time, bats need to spend some time and energy looking for newFAs. Exploratorybehavior is difficult to define operationally, and we have been conservative inidentifying such flights. Heithaus and Fleming (1978) reported that these flights representedonly 1.5%of the estimated 393 km moved by the bats they tracked.

We cannot estimate the frequency of exploratory flights in our dry seasonbats, but one 1977bat (individual D in Fig. 1) provided us with a clear picture of how bats are likely to shift froman old FA to a new one. Between 11 and 18 February this female foraged northwest of theroost as was the case for the bulk of our radio-taggedbats (Fig. 1). Before flying to her northwestFA(s) at 2215 on 20 February, she flew 1 km southeast of the roost (site X in Fig. 1) and wasactive there for three hours. On 21 February, she spent 1.3 hrs in the southeast area beforeflying to the northwest. She foraged in the northwest on the morning of 23 February, butremained in a new area farther south of the roost (site * in Fig. 1) until at least 2300 thatnight. On 24-25 February, she was in the south from 1830 to 1940 and then spent the rest of

November 986 667


10/13

JOURNALOF MAMMALOGY

28----*----

26_25 _.: -.....-23.

< . ?{......IiI.II,---

D 22m 21.Ui. 19 _0 18^ * __ _ ___

Fb15 . The m- .. ....lln..... t n of -F u

I-17

14e3igthe n o nlight On25 and 27 February ._ 7.e e bars_

indicate the time of darkness(both sun and moon below the horizon). Solid lines indicate times that a batwas in the Sendero roost. Bat #051028 was monitored on all nights; its activity is shown just above the"darkness bars." Bat #031028 was monitored from 11 to 19 February and bat #122128 from 22 to 28February. The moon was full on the night of 22 February.

the night in the northwest. On 25 and 27 February she remained south of the roost during thetime she was tracked, and her transmitter fell off in her south FA on 28 February. In summary,this individual gradually changed the location of her feeding site over a period of days byvisiting the new site(s) early in the evening before flying to her old site(s).Bats probably continue returning to a set of FAs as long as possible in both the wet and dryseasons. The relatively short residence time of the transmitter on a bat's back (2-3 weeks)prevents us from directly measuring how long a set of FAs is used. The 1983-84 netting program,however, gives us additional insight into this matter. In the 1983 wet season, for example, theprobability that a bat captured in a resource patch would be recaptured in the same patch onemonth later was 0.67 (n = 51 bats), whereas it was only 0.39 (n = 52 bats) in the 1984 dryseason. These differences are statistically significant (X2 = 8.21, d.f. = 1, P < 0.05) and areconsistent with our prediction that bats should change feeding locations at a higher rate in thedry season than in the wet season.

Vol. 67, No. 468


11/13


Activity rhythms and the response to moonlight.-In both the wet and dry seasons, theactivity of radio-tagged individuals, as measured by tallying the proportionof 15 minute timeblockscontaining one or more actively moving bats during all tracking sessions,was high (0.50-0.60) early in the evening (between sunset and ca. 2100) and again from ca. 0230 to sunrise;activity levels were lowest in the middle of the night (Heithaus and Fleming, 1978). In the wetseason, general levels of activity were not depressed on moonlit nights, but the distance thatbats moved between FAs was negatively related to levels of moonlight (Heithaus and Fleming,1978). The average moving distance on bright nights was only 21% of the distance moved ondark nights.

Moonlighthad a strong effect on activity levels and timing of feeding during the dry season.For example, general activity levels were significantly lower during the first half of the nighton moonlit nights (x = 0.37 ? 0.09 SD) than on dark nights (f = 0.43 ? 0.12) (Binomial Test,n = 18, P = 0.004); levels of moonlight did not influence activity levels during the last half ofthe night (Binomial Test, n = 15, P = 0.85). Bats sometimes stayed in the cave when the moonwas above the horizon early in the evening and did not leave to feed until the moon was down(Fig. 3). Intermittent returns to the cave from distant FAs, however, were no more frequentduring the bright half of the month (n = 6 instances in 1977) than during the dark half (n =7 instances in 1977).

DISCUSSIONBased on knowledge of seasonalchanges in the abundance and distributionof food (fruit and

flower)resources,we predicted that during the dry season individuals of C. perspicillata should(1) forage farther away from their day roost, (2) visit more FAs per night, (3) concentrate theirfeeding activity in a narrowerrange of habitats,and (4) change the locations of their FAs morefrequently than in the wet season. Our radio-trackingand more recently-obtained mist nettingresults indicate that predictions (1), (3), and (4) are likely to be correct. Because a higherproportionof bats fly south to woodlots off park property in the dry season, average commutedistancesprobably are longer than in the wet season. (Calculationsof average distance betweenthe Sendero roost and known FAs (Table 2) did not take these long commutes into accountbecause the locations of FAs outside of the park were not precisely known.) Commute distanceswere significantlylonger in 1977 than in either 1975 or 1976. Batsforage in a variety of habitats,including deciduous, evergreen, and riparianforests in both seasonsbut, based on the results ofmist-netting studies, they tend to be concentrated in fewer resource patches in the dry season.Bats also appear to shift the locations of their FAs more frequently, presumably in response toa higher rate of food species turnover per month in the dry season. Finally, the activity of batsappears to be more strongly influenced by moonlight conditions in the dry season.At least two important features of the foraging behavior of C. perspicillata do not appear tochange seasonally,namely the number of FAs that an individual visits each night and the highnight-to-night consistency with which bats visit a given set of FAs. These unchanging aspectsof foraging in C. perspicillata indicate that individualsuse the same qualitative foraging strategyyear-round.This strategy involves concentrating on fruit species of low nightly density but highspatio-temporalpredictability whenever possible to minimize the energetic costs of commutingand searching for food. A similar strategy is used by the phyllostomid Phyllostomus hastatuson Trinidad (McCrackenand Bradbury, 1981). In contrast, Artibeus jamaicensis concentrateson ephemeral but abundant fruit species (e.g., Ficus species) on BarroColoradoIsland, Panama(Morrison,1978a).Based on radio-trackingdata from four wet seasonsand two dry seasons, it appears that thewet seasonforaging locations of bats roostingin the Sendero Cave are more similar year-to-yearthan are the locationsof dry seasonforaging areas. Only in the dry season of 1977 have we seenSendero bats foraging in numbers west of the roost. In other seasons, most individuals forageeither north or south of the roost. Although we do not know precisely why bats were foragingwest of the roost in 1977, it likely was related to the availability of flowersof Ceiba pentandra,a favorite nectar source of C. perspicillata and other non-specialized flower visiting bats during

November 986 669


12/13

JOURNALOF MAMMALOGY

the dry season in northwestern Costa Rica (Heithaus et al., 1975). We netted individuals of C.perspicillata bearing pollen of C. pentandra at two sites in 1977: near the Sendero roost(within100 m of a flowering individual) and at the Laguna site (Fig. 1). We assume that bats bearingCeiba pollen at Laguna obtained the pollen at that site rather near the roost before flying west.Whatever the reason for the high concentrationof bats in the Laguna area in February 1977,this shift in foraging locations markedly increased the average commute distances of bats inthat seasoncompared to other seasons and years.The intermittent return of many individuals to the day roost also increased overall flightdistance in the dry season. This behavior was seen in males and females and did not alwaysoccur on moonlit nights. These returns do not appear to be associated with increased socialactivity in the roost during the dry season (Williams, 1986). We do not know why bats makelong flights back to the roost before they have finished feeding but speculate that it is relatedto predatoravoidance. If correct, this hypothesis implies that the cost of these irregularflightsis less, in terms of energy expenditure and exposureto predators,than is the regularuse of oneor more night roosts located closer to food sources. The most plausible reason why this mightbe so is that safe night roostsare much scarcer in the dry season when many partsof the forestare leafless.

Another indication that predation risk outside the roost is higher in the dry season than inthe wet season is the response of C. perspicillata to bright moonlight. In our experience, it isunusual for bats to delay departure from the day roost much beyond 0.5 h after sunset in thewet season. Most bats promptly leave the roost, regardlessof time of month or weather condi-tions, near sunset at that time of the year (Heithaus and Fleming, 1978). In contrast, in dryseasonmany individualsdelay their departureor return to the day roostduringperiodsof brightmoonlight (Fig. 3). Since fruit availability is not affected by moonlight, the only plausibleexplanation for this behavior is that it reduces the exposure of C. perspicillata and other fru-givorous (and sanguinivorous)bats to predators(Morrison,1978b; Wilkinson, 1985).In conclusion,the foraging behavior of C. perspicillata appearsto be sensitive to at least threemajorfactors:the abundance and distributionof food, exposure to predators,and social status.Characteristicsof the food supply influence where bats feed, how long they return to the sameset of FAs, and how often they need to search for new FAs. Avoidance of predatorsinfluencesthe bats' choices of night roostsand their activity periods, especially during the leaflessportionof the dry season. Finally, although not a topic of this study, the social status of males (haremmales vs. bachelor males; Porter, 1979) influencestheir foraging behavior. Harem males foragecloser to the day roostand use this roostas their night rooston most nights throughoutthe year,whereas bachelor males, like females, forage at various distances away from the day roostthroughout the year (Williams, 1986). The relative importance of these factors appears to be:food distribution> predatorrisk > social status.

ACKNOWLEDGMENTSIt is a pleasure o acknowledgehe CostaRican NationalParkService AlvaroUgalde,Director) orpermissiono workat ParqueNacionalSantaRosaandtheparkpersonnelor theirsupport ndhospitality.Fieldassistancewasprovidedby Pat Skerrett,MichaelZimmerman,nd SandyMcRae n 1977 and EdStashko, amelaAnderson, ichard tovel,and DebbieShields n 1978.Barbarachneideromputer-coded

the 1977data.Neil Gillieswrote he computer rogramhatsummarizedmostof the 1977radio-trackingdata.Thisresearchwassupported y NSFgrantsDEB75-23450 ndDEB78-26493.Thispaper s Contri-butionNo. 224 from the Programn Ecology,Behavior, nd TropicalBiology,Department f Biology,University f Miami.LITERATURE CITED

ANTHONY,. L. P., ANDT. H. KUNZ. 1977. Feeding 1981. Night roostingand the nocturnaltime bud-strategies f the littlebrownbat,Myotis ucifu- get of the littlebrownbat,Myotis ucifugus: f-gus, in southernNew Hampshire.Ecology,58: fectsof reproductivetatus,preydensity,anden-775-786. vironmentalonditions.Oecologia, 1:151-156.ANTHONY, E. L. P., M.H. STACK,ND T. H. KUNZ. BARCLAY,. M. R. 1982. Nightroosting ehavior

Vol. 67, No. 470


13/13


of the little brown bat, Myotis lucifugus. J.Mamm., 63:464-474.. 1985. Foraging behavior of the Africaninsectivorousbat, Scotophilus leucogaster. Biotro-pica, 17:65-70.BEATTIE,. J. 1971. A technique for the study ofinsect-bornepollen. Pan-PacificEntomol., 47:82.BONACCORSO,. J. 1979. Foraging and reproduc-tive ecology in a Panamanianbat community.Bull.Florida State Mus., Biol. Sci., 24:359-408.BRADBURY,. W. 1977. Lek mating behavior in thehammer-headed bat. Z. Tierpsychol., 45:225-255.BRADBURY,.W., AND . VEHRENCAMP.976. Socialorganization and foraging in emballonurid bats.1. Field studies. Behav. Ecol. Sociobiol., 1:337-381.

DAVIS,W. H., ANDH. B. HITCHCOCK. 1965. Biol-ogy and migration of the bat, Myotis lucifugus,in New England. J. Mamm., 46:296-313.ERKERT. . G. 1982. Ecological aspects of bat ac-tivity rhythms. Pp. 201-242, in Ecology of bats(T. H. Kunz, ed.). Plenum Press, New York.FENTON,M. B., N. G. H. BOYLE, . M. HARRISON,ANDD. J. OXLEY.1977. Activity patterns, habi-tat use, and prey selection by some African insec-tivorous bats. Biotropica,9:73-85.FENTON,M. B., R. M. BRIGHAM,. M. MILLS,ANDI. L. RAUTENBACK.985. The roosting and for-aging areas of Epomophorus wahlbergi (Pteropi-dae) and Scotophilus viridis (Vespertilionidae)inKruger National Park, South Africa. J. Mamm.,66:461-468.FLEMING,. H. 1982. Foraging strategiesof plant-visiting bats. Pp. 287-325, in Ecology of bats (T.H. Kunz, ed.). Plenum Press,New York.

? 1985. Coexistence of five sympatric Piper(Piperaceae) species in a tropical dry forest. Ecol-ogy, 66:688-700.HARTSHORN,. S. 1983. Plants. Pp. 118-183,inCosta Rican natural history (D. H. Janzen, ed.).Univ. Chicago Press,Chicago, Illinois.HEITHAUS, E. R., AND T. H. FLEMING. 1978. For-aging movements of a frugivorous bat, Carolliaperspicillata(Phyllostomatidae).Ecol. Monogr.,48:127-143.

HEITHAUS, E. R., T. H. FLEMING, AND P. A. OPLER.1975. Patterns of foraging and resource utiliza-tion in seven species of bats in a seasonal tropicalforest. Ecology, 56:841-854.HOLDRIDGE,L. R. 1967. Life zone ecology. Trop-ical Science Center, San Jose, Costa Rica.HUMPHREY, S. R., A. R. RICHTER, AND J. B. COPE.

1977. Summerhabitat and ecology of the endan-gered Indiana bat, Myotis sodalis. J. Mamm., 58:334-346.KUNz,T. H. 1974. Feeding ecology of a temperateinsectivorousbat (Myotisvelifer). Ecology, 55:693-711.LEMKE,. 0. 1984. Foraging ecology of the long-

nosed bat, Glossophaga soricina, with respect toresourceavailability. Ecology, 65:538-548.MCCRACKEN, G. F., ANDJ. W. BRADBURY.1981. So-cial organization and kinship in the polygynous

bat Phyllostomus hastatus. Behav. Ecol. Socio-biol., 8:11-34.MORRISON,. W. 1978a. Foraging ecology andenergetics of the frugivorousbat Artibeus jamai-censis. Ecology, 59:716-723.. 1978b. Lunar phobia in a neotropicalbat,Artibeus jamaicensis (Chiroptera: Phyllostomi-dae). Anim. Behav., 26:852-855.O'SHEA, T. J., ANDT. A. VAUGHAN. 977. Noctur-nal and seasonal activities of the pallid bat, An-trozous pallidus. J. Mamm., 58:269-284.PIANKA, . R. 1974. Niche overlap and diffuse

competition. Proc. Natl. Acad. Sci. USA, 71:2141-2145.PORTER,. L. 1979. Social behavior in the leaf-nosed bat, Carollia perspicillata. I. Social organi-zation. Z. Tierpsychol., 49:406-417.START, . N., ANDA. G. MARSHALL.976. Nectar-ivorous bats as pollinatorsof trees in West Malay-sia. Pp. 141-150, in Tropical trees: variation,breeding, and conservation (J. Burley and B. T.Styles, eds.). Academic Press,London.STASHKO,. R. 1982. Foraging ecology of a neo-tropical bat, Carollia perspicillata. Ph.D. dissert.,

NorthwesternUniversity, Evanston, Illinois.STEBBINGS,. E. 1968. Measurements, composi-tion, and behaviour of a large colony of the batPipistrellus pipistrellus. J. Zool., London 156:15-33.THOMAS, . W. 1983. The annual migration ofthree species of West African fruit bats (Chirop-tera: Pteropodidae). Canadian J. Zool., 61:2266-2272.THOMAS,. W., ANDM. B. FENTON.1978. Noteson the dry seasonroostingand foraging behaviourof Epomophorus gambianus and Rousettus ae-gyptiacus (Chiroptera: Pteropodidae). J. Zool.,London 186:403-406.

TUTTLE,M. D. 1976. Population ecology of thegray bat (Myotis grisescens): philopatry, timing,and patternsof movement, weight lossduring mi-gration and seasonal adaptive strategies. Occas.PapersMus. Nat. Hist., Univ. Kansas,54:1-38.VAUGHAN,. A. 1976. Nocturnal behavior of theAfrican false vampire bat (Cardioderma cor). J.Mamm., 57:227-248.WHITAKER,. O., ANDH. BLACK.1976. Food habitsof cave bats from Zambia, Africa. J. Mamm., 57:199-204.WILKINSON,. S. 1985. The social organizationofthe common vampire bat. I. Pattern and cause ofassociation.Behav. Ecol. Sociobiol., 17:111-121.WILLIAMS,. F. 1986. Social organization of thebat Carollia perspicillata (Chiroptera: Phyllo-stomidae). Z. Tierpsychol., 71:265-282.

Submitted 4 December 1985. Accepted 17 March 1986.

November 1986 671

Date post:	06-Apr-2018
Category:	Documents
Upload:	tzanata
View:	220 times
Download:	0 times

Fleming & Heithaus, 1986. Seasonal Foraging Behavior of the Frugivorous Bat Carollia Perspicillata

Documents