Foraging Area Size and Habitat Use by Red Bats (Lasiurus borealis ...

Am. Midl. Nat. 153:405–417

Foraging Area Size and Habitat Use by Red Bats (Lasiurus borealis) in an Intensively Managed Pine Landscape in Mississippi LESLIE W. ELMORE1 Mississippi Cooperative Fish and Wildlife Research Unit, Mississippi State 39762

DARREN A. MILLER2 Southern Timberlands R&D, Weyerhaeuser Company, P.O. Box 2288, Columbus, Mississippi 39704 AND

FRANCISCO J. VILELLA Mississippi Cooperative Fish and Wildlife Research Unit, Mississippi State 39762 ABSTRACT.—Forest managers are increasingly expected to incorporate biodiversity objectives within forest landscapes devoted to timber production. However, reliable data on which to base management recommendations for bats within these systems are extremely limited. Although the red bat (Lasiurus borealis) is a widespread common species in temperate forests of North America, little is known of its ecology within intensively managed pine (Pinus spp.) forests of the southeastern United States. Therefore, we investigated size of foraging areas and habitat use by red bats during summer 2000 and 2001 in an intensively managed pine landscape in east-central Mississippi, USA. We captured bats using four-tier mist nets placed over water and attached radiotransmitters to red bats. Radiotagged red bats (n ¼ 16) used habitat types randomly at the study area and foraging area scale. Mean size of foraging areas and mean maximum distance traveled between diurnal roosts and foraging locations were not different (P , 0.05) among adult male, adult female, juvenile male or juvenile females (n ¼ 18). Most foraging areas contained a reliable source of water and all but one diurnal roost was located within foraging areas. Location of diurnal roosts may dictate location of foraging areas. Open canopy conditions in intensively managed pine stands (young, open canopy stands, thinned stands and riparian hardwood stands) likely provide appropriate foraging habitat for red bats. Landscape context may influence size of foraging areas and commuting distances of red bats. Provision of appropriate aged forest stands for diurnal roosts may be the best management action for red bats within intensively managed pine landscapes.

INTRODUCTION Within the southeastern United States, intensively managed pine (Pinus spp.) forests are a primary forest type with total area of these forests expected to increase from 12.9 million ha in 1999 to 21.8 million ha in 2040 (Wear and Greis, 2002). Although intensively managed forests can support a diversity of wildlife species (e.g., Perkins et al., 1988; Wigley et al., 2000; Wilson and Watts, 2000), little information is available regarding bat communities within these landscapes (Campbell et al., 1996; Miller, 2003). Bats are an important component of forested ecosystems that are likely affected by forest management (e.g., Campbell et al., 1996; Krusic and Neefus, 1996; Morrell et al., 1999). As forest managers are increasingly being 1

Present address: Division of Wildlife Resources, 1594 W. North Temple, Suite 2110, Salt Lake City, Utah 84116 2 Corresponding author: Telephone: (662)245-5249; FAX: (662)245-5228; e-mail: darren.miller@ weyerhaeuser.com

405

406

THE AMERICAN MIDLAND NATURALIST

153(2)

asked to consider biodiversity (American Forest and Paper Association, 2002), reliable data on suitability of managed forests for wildlife species, including bats, are needed (Miller et al., 2003). Although research on habitat relations of bats in managed forests has been conducted (Thomas, 1988; Erickson and West, 1996; Hayes and Adam, 1996; Grindal and Brigham, 1999; Humes et al., 1999; Jung et al., 1999), such data are limited for the southeastern United States in general and managed pine landscapes in particular. Although red bats (Lasiurus borealis) are one of the most common and widely distributed bat species in North America (Barbour and Davis, 1969; Shump and Shump, 1982), quantitative data on size of foraging areas and habitat use are limited. Furlonger et al. (1987) found that red bats in southwest Ontario were active over terrestrial habitats (e.g., fields and forests) significantly more than over water habitats (e.g., ponds and streams). However, in Kentucky, Hutchinson and Lacki (1999) determined red bats in mixed mesophytic forests foraged over water more than expected. In the White Mountain National Forest in New Hampshire, red bats were most active over water, but within forests, their activity did not differ between hardwood and softwood habitats (Krusic and Neefus, 1996). Carter (1998), working in South Carolina, documented size of foraging areas and habitat use of red bats within a landscape that had 27% of the study area in pine forest. He found red bats most often used bottomland hardwood stands followed by pine stands, with bottomland hardwoods preferred over upland hardwoods. Because red bats may have different habitat use patterns across their geographic range, comparisons among different forested landscapes and biogeographical regions may not be appropriate. Scant information exists about red bat foraging and habitat ecology in landscapes dominated by intensively managed pine stands. Our objectives were to examine size of foraging areas and habitat use of red bats in a landscape dominated by intensively managed, short-rotation pine plantations with the goal of better understanding ecology of red bats within such landscapes. METHODS STUDY AREA

We conducted our study on approximately 24,000 ha of mostly contiguous, intensively managed loblolly pine forest, owned and managed by Weyerhaeuser Company for the production of pine sawtimber, in Kemper County, Mississippi. We defined a 4000 ha study site within the study area as the area encompassing all foraging locations and day roost sites of radiotagged red bats, with a 100 m buffer around the entire area (Welch, 2003). This area was located in the Interior Flatwoods of the East Gulf Coastal Plain, approximately 6 km southwest of Scooba, Mississippi, USA (328479300E, 888309610N). Topography was flat with numerous ephemeral, intermittent and perennial streams. Dominate overstory tree species included loblolly pine, oaks (Quercus spp.) and hickory (Carya spp.). Common midstory species included oaks, hickory, maple (Acer spp.), sweetgum (Liquidambar spp.) and dogwood (Cornus spp.). Confirmed bat species present on this area were red bat, Seminole bat (Lasiurus seminolus), evening bat (Nycticeius humeralis), eastern pipistrelle (Pipistrellus subflavus), hoary bat (Lasiurus cinereus) and southeastern myotis (Myotis austroriparius; Miller, 2003). Typical silviculture on this area included clearcut harvest of pine plantations at approximately 27–32 y of age followed by site preparation and planting, vegetation management, one or two commercial thinnings, pruning and fertilization. Non-plantation habitats, comprising approximately 15% of the area, included mature pine-hardwood and hardwood forests, associated with streamside management zones (SMZs) and in isolated upland sites and small (,5 ha) wildlife openings. Adjacent land was primarily forested. Mississippi had a warm humid climate, with long summers and short mild winters;

2005

ELMORE ET AL.: RED BATS HABITAT USE

407

temperatures averaged approximately 28 C in July and 9 C in January. Average temperatures for summers of 2000 and 2001 were 26.6 and 24.6 C, respectively. Average monthly precipitation for summers of 2000 and 2001 was 2.64 and 4.63 cm, respectively (National Oceanic and Atmospheric Administration, www.srh.noaa.gov). We classified stands within the study site using a geographic information system (GIS) developed by Weyerhaeuser Company, information from Weyerhaeuser Company foresters and ground-truthing. We characterized five habitats within the study area based on stand type and thinning history. The five habitats were: (1) young open pine stands (0–8 y old pine plantations with open canopies), (2) closed canopy pine stands (approximately 9–15 y old pre-thinned pine plantations with closed canopies), (3) thinned pine stands (13–37 y old thinned pine plantations with open canopies), (4) mixed pine-hardwood (150 ha stand of non-Weyerhaeuser, unmanaged forest with closed canopy; approximately 10–15 y old) and (5) SMZs that included pines and hardwoods at least 80 y old. Due to timber harvest during the study, relative proportion of thinned stands and young open pine stands changed. During the four radiotracking periods (see below; Jun.–Jul. 2000, Aug. 2000, Jun. 2001 and Jul. 2001), proportion of the landscape in thinned pines stands was 68%, 67%, 63% and 60%, respectively. Correspondingly, proportion of the landscape in young open pine was 17%, 18%, 22% and 25%, respectively. Additionally, 7% of the study site was in SMZs, 4% was in mixed pine-hardwood, 3% in closed canopy pine plantation and 1% in food plots, odd areas and nonstocked land. OBTAINING BAT LOCATIONS

We captured bats over water at four separate sites using four-tier mist nets during Jun.– Aug. 2000 and May–Jul. 2001. We conducted mist-netting once per month at one or two sites per night for up to four consecutive nights, or until a maximum of 10 red bats had been radiotagged. We recorded species, gender, age, weight (g), forearm length (cm) and reproductive status (e.g., scrotal, lactating, non-lactating) of all captured bats (Racey, 1988). We classified bats as adults or juveniles by shining a light through the wing membrane and observing degree of fusion of the finger joints (Anthony, 1988). All red bats weighing at least 8 g received a 0.47–0.54 g LB-2 radiotransmitter (Holohil Systems Limited, Ontario, Canada). Mean radiotransmitter load was 4.66% (range ¼ 3– 6.75%) of the body mass of radiotagged bats (Aldridge and Brigham, 1988). We trimmed the fur between the scapulae prior to radiotransmitter attachment and used Skin-bondÒ surgical cement (Smith and Nephew United, Largo, Florida, USA) to secure radiotransmitters. Juvenile red bats have been observed having difficulty flying after radiotransmitter attachment (M. Lacki, Univ. of Kentucky, pers. comm.). However, we did not directly observe any abnormal behavior by radiotagged juveniles, juveniles had similar foraging area size as adults (see Results) and juveniles traveled similar distances as adults among consecutive roost sites and between roosts sites and foraging areas (Welch, 2003). Therefore, we assumed that transmitter attachment did not influence behavior of juvenile bats. All bat capture and handling procedures were approved by the Mississippi State University Institutional Animal Care and Use Committee protocol number 00-038. Seminole bats, which closely resemble red bats, were common on our study area (Miller, 2003). Distinguishing between the two species in hand is based on pelage characteristics (Barbour and Davis, 1969; Sealander and Heidt, 1990). In our area, female red bats and Seminole bats were sometimes difficult to distinguish, especially under artificial light. Therefore, we did not radiotag any bats that were not definitively identified as red bats. We used Wildlife Materials TRX-2000S radio receivers (Wildlife Materials, Inc., Carbondale, Illinois, USA) within the 148.000–149.999 MHZ frequency range and three-element

408


153(2)

Yagi antennas to obtain locations of day roosts of radiotagged bats. We located, flagged and recorded universal transverse mercator (UTM) coordinates for day roosts of all radiotagged bats beginning two mornings after capture. We did not document day roosts of bats the day after capture to minimize roosts selected by bats while adjusting to capture and handling procedures. This was done because on several occasions we observed released red bats flying to the nearest large tree where they remained throughout the night. However, these bats were usually located in a different roost tree the following day, thus indicating a possible bias due to capture and handling. To triangulate foraging locations, we established individually numbered and flagged radiotelemetry stations (n ¼ 165) throughout the study area, generally separated by approximately 350 m. We recorded UTM coordinates of these stations. We began telemetry on radiotagged bats the evening after capture to avoid recording unusual movements on the night of capture. We conducted telemetry nightly, beginning 30 min before sunset and ending 30 min after sunrise, for up to 10 consecutive nights or until the transmitter could no longer be heard. Two or three field personnel equipped with TRX-2000S receivers, threeelement Yagi antennas, compasses and two-way radios recorded simultaneous azimuths on radiotagged bats from the established radiotelemetry stations. We used all radiolocations when three azimuths were recorded and all three of the azimuths intersected. If only two azimuths intersected, either because only two were recorded or one of three did not cross, we only included locations when the difference in the azimuths was between 45 and 135 degrees. If the difference did not fall in this range, we deleted the location as such an angle greatly increases deviation from the true location to the estimated location. We did not explicitly test for radiotelemetry error. However, because we were selective in which locations we used and because of the habitat use analysis used (see below), we do not believe that error produced significant biases in data interpretation. We attempted to locate each bat every 15 min. We recorded bat activity (determined by fluctuating radiotransmitter signal strength) as an indication of whether the bat was foraging or night roosting and signal strength. Because we obtained bearings at irregular intervals and because locations were more easily and commonly recorded near the roosting areas of the bats, we discarded bearings that were recorded less than 30 min apart to more realistically estimate size of foraging areas and habitat use. Moreover, this procedure helped meet the assumption of independence of successive locations (Swihart and Slade, 1985; White and Garrot, 1990). We placed bats into four ‘‘classes’’ based on age and gender (adult male, adult female, juvenile male and juvenile female). We defined tracking period as the month and year that bats were captured and tracked (four periods, Jun.–Jul. 2000, Aug. 2000, Jun. 2001, Jul. 2001). Due to short radiotransmitter battery life, no bats were monitoring for more than one tracking session. FORAGING AREA ANALYSES

To determine size of foraging areas, we used the default settings in program Locate II (Nams, 2000) to generate UTM coordinates of bat locations using 2–3 bearings taken from UTM-located radiotelemetry stations. We imported location coordinates for each bat into ArcView 3.2 (ESRI, 1996) and generated home ranges using the 95% adaptive kernel estimator within the Animal Movement extension (Hooge and Eichenlaub, 1997). We used the adaptive kernel method (Worton, 1989) because it is a nonparametric technique that is less affected by fewer observations than are other techniques (e.g., minimum convex polygon; Hansteen et al., 1997). Home range estimation of mammals is often feasible using 20–40 independent radiotelemetry locations (Hawes, 1977; Seaman et al., 1999). We included all bats (n ¼ 17) with at least 30 locations in the analyses. We also included a juvenile female with

2005


409

24 locations because few juvenile females were radiotracked. This number of locations is similar to what other bat studies have used in the southeastern United States (e.g., Adam et al., 1994; Carter, 1998; Menzel et al., 2001). With the bat as the experimental unit, we tested the null hypothesis that no difference in size of foraging areas existed among bat classes. Due to sample size constraints, we pooled bats across tracking periods (White and Garrot, 1990). For the above hypothesis, we examined data for homogeneity of variance using Levene’s test. Data with unequal variances were reciprocally transformed to meet homogeneity of variance assumptions (Zar, 1974). If the transformed data had variance homogeneity, we used a two-way analysis of variance (ANOVA) to test hypotheses using gender and age as independent variables. Data that did not meet homogeneity of variance assumptions after transformation were analyzed using a Friedman’s test (Daniel, 1990). We used the least significant means procedure for mean separation. All data were analyzed using SAS 8.0 (SAS Institute, 2001). We used an alpha level of 0.05 for all tests. We also estimated maximum distances (m) from day roost sites to foraging locations for radiotagged bat using the XTools extension (http://arcscripts.esri.com/details. asp?dbid¼11526) in ArcView 3.2 (ESRI, 1996). This was done to estimate maximum distance bats traveled from diurnal roosts to foraging locations. We then calculated a mean maximum distance for each bat by averaging maximum distances traveled each night. We used a two-way mixed model ANOVA to compare maximum distance moved among bat classes. HABITAT USE ANALYSES

As stated above, timber harvest resulted in landscape changes within and between years. Consequently, four ‘‘snapshots’’ were designated by creating four GIS coverages that corresponded with habitat conditions during the 4 tracking periods. Bat foraging areas were overlaid on the habitat coverage appropriate for each tracking session in ArcView 3.2 (ESRI, 1996) to relate bat locations to the habitat coverage. We used Euclidean distances (Conner and Plowman, 2001; Conner et al., 2003) to examine habitat use of radiotagged red bats. The Euclidean distance technique, like compositional analysis (Aebischer et al., 1993), uses the animal as the sampling unit. This technique did not assign estimated locations to habitat types but rather uses distances from estimated locations to all available habitat types. We used our GIS to generate distances between each estimated bat foraging location and each different habitat type. A distance value of zero was assigned for the habitat type in which the foraging location was estimated to occur. These distances were then compared to a null model to determine if habitat selection occurred and to rank habitats in order of preference (Conner et al., 2003). Habitat data were analyzed with multivariate analysis of variance (MANOVA), allowing for testing of main effects (bat class) relative to habitat use. As the Euclidean distance approach does not require the animal to be ‘‘assigned’’ to a particular habitat, it is extremely robust to radiotelemetry error (Conner and Plowman, 2001; Conner et al., 2003). We estimated habitat use at two spatial scales. At the foraging area scale, animal locations represented habitat use and each foraging area represented available habitat. At the study area scale, animal locations represented habitat use and available habitat was that contained within the entire study site. Similar to the foraging area analyses, we pooled bats across tracking periods. RESULTS We captured 163 bats (64 red bats, 45 evening bats, 41 Seminole bats and 13 eastern pipistrelles) during Jun.–Aug. 2000 and May–Jul. 2001 (Table 1). Of the 64 red bats, we attached radiotransmitters to 46 of them; 12 were too small for radiotransmitters, four escaped prior to radiotransmitter attachment and two experienced mortality upon capture.

410


153(2)

TABLE 1.—Number of bats captured, by species, age and gender in Kemper County, Mississippi, summer, 2000 and 2001. This table does not include captures that did not have species, age and/or sex determined (bats captured that escaped prior to this determination) Capture period Age/Gendera

Jun.–Jul. 2000

Aug. 2000

Jul. 2001

Total

Lasiurus borealis

AF AM JF JM

9 0 2 11

2 8 0 4

6 4 0 0

2 0 5 3

19 12 7 18

Nycticeius humeralis

AF AM JF JM

2 1 0 1

4 4 1 1

11 1 0 0

1 1 0 0

18 7 1 2

Lasiurus seminolus

AF AM JF JM

4 0 17 5

10 2 2 0

1 0 0 0

0 0 0 0

15 2 19 5

Pipistrellus subflavus

AF AM JF JM

0 0 2 2

0 0 0 0

1 0 0 0

1 0 1 0

2 0 3 2

Species

a

Jun. 2001

AF ¼ adult female; AM ¼ adult male; JF ¼ juvenile female; JM ¼ juvenile male

We did not obtain signals from 19 bats for a variety of reasons (e.g., dropped radiotransmitters, moved out of the study area, radiotransmitter not functioning) and 9 bats had too few locations for tracking. We radiotracked three adult females during Jun.–Jul. 2000, one during Aug. 2000 and three during June 2000. We radiotracked one adult male during Aug. 2000 and two during Jun. 2001. We radiotracked three juvenile females during July 2001. We radiotracked two juvenile males during Jun.–Jul. 2000, two during Aug. 2000 and one during July 2001. Mean number of days (6SE) we tracked bats was 7 6 0.5 for adult females, 8 6 0.8 for adult males, 4 6 0.8 for juvenile females and 7 6 0.7 for juvenile males. We included 18 red bats (7 adult females, 3 adult males, 3 juvenile females and 5 juvenile males; Table 2) in foraging area analyses with an average of 46.9 locations (range 24–128; Table 2) per bat. Size of foraging areas was not correlated with number of locations (r2 ¼ 0.14, P ¼ 0.12). Foraging areas were composed of 1–7 distinct areas of activity (Table 2, Fig. 1) and foraging areas of red bats captured at the same site often overlapped. Similar to size of foraging areas, there was no relation between number of areas of activity and number of locations (r2 ¼ 0.02, P ¼ 0.61). There was no interaction between age and gender for size of foraging areas (F1,14 ¼ 2.02, P ¼ 0.178). Size of foraging areas did not differ between males (n ¼ 8) and females (n ¼ 10; F1,14 ¼ 0.00, P ¼ 0.96) nor between adults (n ¼ 10) and juveniles (n ¼ 8; F1,14 ¼ 0.24, P ¼ 0.63). Mean size of foraging areas was 94.2 6 26.7 for males, 94.5 6 30.6 for females, 101.6 6 28.9 for adults and 85.4 6 29.4 for juveniles (Table 2). For all bat classes combined, average size of foraging areas was 94.4 6 20.2 ha (Table 2). Mean maximum distance traveled from diurnal roosts to foraging locations varied from 0.19 km–2.85 km for adult females, 0.64 km–3.28 km for adult males, 0.99 km–1.64 km for juvenile females and 0.48 km–1.02 km for juvenile males (Table 2). There was not an age by gender interaction (F1,14 ¼ 1.92, P ¼ 0.188) for mean maximum distance traveled. Similarly,


2005

411

TABLE 2.—Mean and standard error (SE) for radiotelemetry locations, size of foraging areas (ha), maximum distance from diurnal roosts to foraging locations (km; distance moved) and number of activity centers (adaptive kernel estimator) for radiotagged red bats in Kemper County, MS, summer 2000 and 2001 Radiotelemetry locations

Size of foraging area

Maximum distance traveled

Number of activity centers

Age/Gendera

Mean

SE

Mean

SE

Mean

SE

Mean

SE

AF (n ¼ 7) AM (n ¼ 3) JF (n ¼ 3) JM (n ¼ 5)

59.8 39.3 32.7 42.0

11.7 4.7 5.5 5.8

82.1 146.7 123.0 62.6

31.8 63.3 80.3 11.7

1.2 2.1 1.4 0.7

0.34 0.8 0.2 0.1

2.3 2.3 4.7 2.2

0.6 0.9 1.5 0.5

a


no differences were detected between adults and juveniles (F1,14 ¼ 0.04, P ¼ 0.852), or between males and females (F1,14 ¼ 0.03, P ¼ 0.867). During one monthly telemetry session, timber harvesting was occurring in the same area as we were tracking bats for approximately 4 d, resulting in a dynamic landscape. We excluded two adult females from habitat analyses as we could not ascertain what habitats were available to them during this time. Therefore, we used 16 red bats (5 adult females, 3 adult males, 3 juvenile females and 5 juvenile males) for habitat analyses. Red bats exhibited no preferences for particular habitats within foraging areas (F5,8 ¼ 0.20, P ¼ 0.954, Wilk’s Lambda ¼ 0.89; Table 3). We did not detect an age by gender interaction for habitat selection within foraging areas (F5,8 ¼ 0.67, P ¼ 0.66, Wilk’s Lambda ¼ 0.71). Males and females did not select habitat differently (F5,8 ¼ 1.00, P ¼ 0.476, Wilk’s Lambda ¼ 0.62) within foraging areas, nor did adults and juveniles (F5,8 ¼ 0.07, P ¼ 0.995, Wilk’s Lambda ¼ 0.96). Habitat selection within the study area was not detected with regards to age (F5,8 ¼ 0.57, P ¼ 0.726, Wilk’s Lambda ¼ 0.74), gender (F5,8 ¼ 0.49, P ¼ 0.775, Wilk’s Lambda ¼ 0.77) or age by gender interaction TABLE 3.—Mean distance (m) from radiotelemetry locations of red bats to each habitat type, Kemper County, Mississippi, during summer 2000 and 2001 at two scales of habitat availability (within the entire study area and within foraging areas). Habitat types were: young, open pine plantation (Young), close canopy pine plantation (Closed), thinned pine plantations (Thinned), mixed pine-hardwood (Mixed) and streamside management zone (SMZ) Young Age/Gendera

Closed

Thinned

Mixed

SMZ

Mean

SE

Mean

SE

Mean

SE

Mean

SE

Mean

SE

473 508 183 443

6 7 5 5

1685 1046 1290 1957

15 9 15 26

13 11 17 10

1 2 2 1

1761 1344 1728 2009

8 8 13 7

186 224 403 141

6 4 10 3

443 454 169 433

7 8 3 5

1697 1092 1226 1972

17 9 15 20

16 16 26 10

2 3 2 1

1747 1333 1662 2026

9 8 14 8

172 253 315 158

6 4 9 3

Within foraging areas AF (n ¼ 5) AM (n ¼ 3) JF (n ¼ 3) JM (n ¼ 5) Within study area AF (n ¼ 5) AM (n ¼ 3) JF (n ¼ 3) JM (n ¼ 5) a


412


153(2)

FIG. 1.—Foraging areas, as determined with a kernel estimator, for selected red bats to demonstrate multiple centers of activity within a landscape of intensively managed pine forest in Kemper County, MS, summer 2000 and 2001. Examples are of an adult female (Bat 001), adult male (Bat 015), juvenile female (Bat 046) and juvenile male (Bat 007). Habitat types were streamside management zone (SMZ), thinned loblolly pine stands (post-thinned pine), young open canopy pine stands (Open) and closed canopy mixed pine-hardwood forest (MPH)

(F5,8 ¼ 0.63, P ¼ 0.68, Wilk’s Lambda ¼ 0.72; Table 3). Overall, habitat types within the study area were used randomly (F5,8 ¼ 0.54, P ¼ 0.743, Wilk’s Lambda ¼ 0.75). DISCUSSION Reported sizes of foraging areas were most likely underestimates due to difficulties in maintaining contact with radiotagged bats (e.g., short transmitter range, lack of roads in

2005


413

some parts of the study area and ability of red bats to travel quickly over large distances; e.g., Hutchinson and Lacki, 1999). Further, because of small sample sizes, it is possible that differences among bat classes existed but were not detected. Finally, data interpretations regarding centers of activity must be done cautiously given the low number of radio locations per center of activity for some bats. Red bats are fast fliers and concentrate foraging activity from below tree top level down to only inches above the ground (Barbour and Davis, 1969; Sealander and Heidt, 1990) predisposing them to forage over uncluttered habitat such as clearcuts and thinned stands (Hart et al., 1993; Jung et al., 1999). Jung et al. (1999) suggested red bats prefer open stands in conifer-dominated systems. Additionally, thinned forest stands in general have been documented as important foraging habitat for bats (Thomas, 1988; Humes et al., 1999). Given that approximately 90% of our study area was young open pine stands, thinned stands and mature hardwood stands, it is possible that most of the area offered similar foraging space for red bats. Young open pine stands were recent (,9 y old) clearcuts, providing open foraging space. Thinned stands had approximately 250 overstory pine trees/ha which provided an open canopy condition throughout the stand with a varying density of midstory hardwoods (Wilson and Watts, 2000). This forest structure provided open foraging space below the pine canopy and above the midstory layer. Mature hardwood stands were located primarily along streams with an open forest structure and was the most often used habitat by red bats in South Carolina (Carter, 1998). Preponderance of open habitat conditions on our study area likely explains lack of demonstrable habitat preference by red bats. As documented for red bats in Kentucky, all foraging areas contained a water source (Hutchinson and Lacki, 1999). Red bats are often observed flying low over water to drink and capture insects (Sealander and Heidt, 1990) and in Kentucky, seemed to select water proportionally higher than available (Hutchinson and Lacki, 1999). Most of the water sources on our area were streams possibly providing travel corridors for red bats (T. Jung, pers. comm.). Given that this species seems to be a habitat generalist able to forage over a diversity of habitat types (e.g., Furlonger et al., 1987; Hart et al., 1993; Carter, 1998; Hutchinson and Lacki, 1999; this study), a reliable water source may be more important for drinking or as travel corridors (i.e., streams) than foraging. Similar to past studies (McCracken et al., 1997; Hutchinson and Lacki, 1999), all diurnal roosts in our study, except one, were located in the respective bat’s foraging area. According to Kunz (1982), this would be expected to help reduce energy expenditure from commuting. However, the conclusion of Kunz (1982) is counter to that of Hutchinson and Lacki (1999) who observed similar size of foraging areas and commuting distances for red bats as for caveroosting bats (Corynorhinus spp.) in the same area of eastern Kentucky. They posited that foraging areas may be determined by location of preferred diurnal roosts. On our study area, red bats switched roosts frequently but roosts for each bat were mostly located in a small (,1 ha) area, indicating a preference for certain stand characteristics (Welch et al., 2004). Given that red bats on our area displayed roost site selection but not habitat selection, our study suggests that location of diurnal roosts may be more important than location of foraging areas. Additionally, because red bats are fast flyers (Barbour and Davis, 1969) and able to quickly cover distances, it is likely less important for red bats to choose locations of diurnal roosts based on location of foraging sites. This evidence supports the conclusion of Hutchinson and Lacki (1999) regarding relations between foraging areas and diurnal roosts. In Kentucky, maximum distance from diurnal roosts to foraging sites was 1.2 to 5.5 km for females and 1.4 to 7.4 km for males (Hutchinson and Lacki, 1999). We found that mean maximum distances moved were within this range, but tended to be lower than reported by Hutchinson and Lacki (1999). Similarly, size of foraging areas was considerably smaller than

414


153(2)

reported by Hutchinson and Lacki (1999; mean of 334 ha) in upland hardwood forests and Carter (1998; mean of 453 ha) in an area dominated by bottomland hardwoods with associated upland pine and hardwood forests. McCracken et al. (1997) reported home ranges of four red bats on the Galapagos Islands as between 10–20 ha that were concentrating foraging activity around street lights. Although our foraging areas were mostly larger than those reported by McCracken et al. (1997), we observed four bats that had comparable foraging area sizes (3 ha and 14 ha for two adult females 21 ha for an adult male and 24 ha for a juvenile male). However, there were no permanent dwellings or street lights within our study area and the closest artificial light was at least 3 km from our study area. Therefore, bats in this study were not able to exploit artificially high concentrations of insects as reported in other studies (Furlonger et al., 1987; McCracken et al., 1997; Hutchinson and Lacki, 1999). The smaller foraging areas in our study compared to those reported by Hutchinson and Lacki (1999) and Carter (1998) could be the result of differences in landscape characteristics. Our study was conducted in a contiguous forested area, whereas Hutchinson and Lacki (1999) found shorter commuting distances in a less fragmented forest landscape, suggesting that large blocks of forest may provide better habitat. It may be argued that our study area, because it is intensively managed, is actually a fragmented forest given the relatively small stand sizes and mixture of clearcuts with older plantations and mature forests. However, given the lack of habitat preference we observed and because a large proportion of the study area was potential foraging habitat, our study area can likely be considered contiguous for red bats. We agree with Hutchinson and Lacki (1999) that landscape context dictates foraging habitat for red bats but would suggest that intensively managed landscapes can provide high quality foraging habitat for red bats, depending on proportion of the area with an open canopy. Red bats in our study had at least one, and usually several, areas of activity (Fig. 1). This has not been previously documented for this species. These areas of high activity likely resulted from two factors. First, red bats may have been exploiting localized insect abundance as has been observed for this species around artificial light (Barbour and Davis, 1969; Hickey and Fenton, 1990; McCracken et al., 1997). Second, red bats have been observed to forage repeatedly along established routes (Barbour and Davis, 1969), which may be represented by these centers of activity. It is unclear if these areas of high activity were associated with specific habitat characteristics, but it does suggest that although red bats may be generalists, there are specific foraging areas that are used disproportionately. Use of intensively managed forests by red bats is not indicative of the potential of these landscapes to provide foraging habitat for other bat species (e.g., Jung et al., 1999). As stated previously, red bats appear very adaptable to a wide range of forest conditions, the common feature being open habitat for foraging. Other species that occur in the southeast region may not demonstrate the same habitat plasticity as red bats and thus may not be as tolerant of management practices within intensively managed pine landscapes. Further research is the only means to fully document the conservation value of intensively managed pine landscapes for bat communities. Within our study area, providing appropriate forest stands (SMZs and post-thinned pine plantations) for diurnal roosts of red bats may be the most practical management action to maintain this species on the landscape. This is based on selectiveness of red bats for roosting sites (Welch et al., 2004) and apparent lack of selectiveness for foraging areas. However, the landscape in our study was dominated by open canopy conditions which are highly conducive to foraging for red bats (Jung et al., 1999). Landscapes with a high proportion of the forest in a closed canopy condition may restrict foraging opportunities for red bats, which may make them become more selective regarding habitat use.

2005


415

Acknowledgments.—Funding was provided by Weyerhaeuser Company; Department of Wildlife and Fisheries, Forest and Wildlife Research Center, Mississippi State University; the National Council on Air and Stream Improvement; Bat Conservation International; and International Paper. We are grateful to the Joseph W. Jones Ecological Research Center (Newton, GA) and the Utah Department of Natural Resources for use of facilities for the senior author during her graduate work. We thank T. C. Carter, L. M. Conner, T. Jung and two anonymous reviewers for manuscript reviews; T. B. Wigley and D. Taylor provided logistic support. We thank R. Crandall, B. Davis, L. DeGroote, A. Quig and J. Sloan for assistance in the field.

LITERATURE CITED ADAM, M. D., M. J. LACKI AND T. G. BARNES. 1994. Foraging areas and habitat use of the Virginia big-eared bat in Kentucky. J. Wildl. Manage., 58:462–469. AEBISCHER, N. J., P. A. ROBERTSON AND R. E. KENWARD. 1993. Compositional analysis of habitat use from animal radio-tracking data. Ecology, 74:1313–1325. ALDRIDGE, H. D., J. N. AND R. M. BRIGHAM. 1988. Load carrying and maneuverability in an insectivorous bat: a test of the 5% ‘‘rule’’ of radio-telemetry. J. Mamm., 69:379–382. AMERICAN FOREST AND PAPER ASSOCIATION. 2002. Sustainable Forestry InitiativeÒ (SFI) Program: 2002–2004 SFI Standard and Verification Procedures. American Forest and Paper Association, Washington, D.C. 47 p. ANTHONY, E. L. P. 1988. Age determination in bats, p. 47–58. In: T. H. Kunz (ed.). Ecological and behavioral methods for the study of bats. Smithsonian Institution Press, Washington, D.C. BARBOUR, R. W. AND W. H. DAVIS. 1969. Bats of America. University of Kentucky Press, Lexington. 286 p. CAMPBELL, L. A., J. G. HALLETT AND M. A. O’CONNELL. 1996. Conservation of bats in managed forests: use of roosts by Lasionycteris noctivagans. J. Mamm., 77:976–984. CARTER, T. C. 1998. The foraging ecology of three species of bats at the Savannah River Site, South Carolina. M.S. Thesis, University of Georgia, Athens. 74 p. CONNER, L. M. AND B. W. PLOWMAN. 2001. Using Euclidean distances to assess nonrandom habitat use, p. 275–290. In: Joshua J. Millspaugh and John M. Marzluff (eds.). Radiotelemetry and animal populations. Academic Press, San Diego, California. ———, M. D. SMITH AND L. W. BURGER. 2003. A comparison of distance-based and classification-based analyses of habitat use. Ecology, 84:526–531. DANIEL, W. W. 1990. Applied nonparametric statistics, 2nd ed. PWS-KENT Publishing Company, Boston, Massachusetts. ERICKSON, J. L. AND S. D. WEST. 1996. Managed forests in the western Cascades: the effects of seral stage on bat habitat use patterns, p. 215–227. In: R. M. R. Barclay and R. M. Brigham (eds.). Bats and Forests Symp. British Columbia Ministry of Forests, Victoria. ESRI. 1996. ArcView GIS. Redlands, California. 340 p. FURLONGER, C. L., H. J. DEWAR AND M. B. FENTON. 1987. Habitat use by foraging insectivorous bats. Can. J. Zool., 65:284–288. GRINDAL, S. D. AND R. M. BRIGHAM. 1999. Impacts of forest harvesting on habitat use by foraging insectivorous bats at different spatial scales. Ecoscience, 6:25–34. HANSTEEN, T. L., H. P. ANDREASSEN AND I. A. ROLF. 1997. Effects of spatiotemporal scale on autocorrelation and home range estimators. J. Wildl. Manage., 61:280–290. HART, J. A., G. L. KIRKLAND, JR. AND S. C. GROSSMAN. 1993. Relative abundance and habitat use by tree bats, Lasiurus spp., in southcentral Pennsylvania. Can. Field Natur., 107:208–212. HAWES, M. L. 1977. Homerange, territoriality and ecological separation in sympatric shrew, Sorex vagrans and Sorex obscurus. J. Mamm., 58:354–367. HAYES, J. P. AND M. D. ADAM. 1996. The influence of logging riparian areas on habitat utilization by bats in western Oregon, p. 228–237. In: R. M. R. Barclay and R. M. Brigham (eds.). Bats and Forests Symp. British Columbia Ministry of Forests, Victoria. HICKEY, M. B. C. AND M. B. FENTON. 1990. Foraging by red bats (Lasiurus borealis): do intraspecific chases mean territoriality? Can. J. Zool., 68:2477–2482.

416


153(2)

HOOGE, P. N. AND B. EICHENLAUB. 1997. Animal movement extension in ArcView, Version 1.1. Alaska Biological Science Center, U.S. Geological Survey, Anchorage. Unpaginated. HUMES, M. L., J. P. HAYES AND M. W. COLLOPY. 1999. Bat activity in thinned, unthinned and old-growth forests in western Oregon. J. Wildl. Manage., 63:553–561. HUTCHINSON, J. T. AND M. J. LACKI. 1999. Foraging behavior and habitat use of red bats in mixed mesophytic forests of the Cumberland Plateau, Kentucky, p. 171–177. In: J. W. Stringer and D. L. Loftis (eds.). 12th Central Hardwood Forest Conf., U. S. For. Serv., South. Experiment Stat., Asheville, North Carolina. JUNG, T. S., I. D. THOMPSON, R. D. TITMAN AND A. P. APPLEJOHN. 1999. Habitat selection by forest bats in relation to mixed-wood stand types and structure in central Ontario. J. Wildl. Manage., 63: 1306–1319. KRUSIC, R. A. AND C. D. NEEFUS. 1996. Habitat associations of bat species in the White Mountain National Forest, p. 185–198. In: R. M. R. Barclay and R. M. Brigham (eds.). Bats and Forests Symp. British Columbia Ministry of Forests, Victoria. KUNZ, T. H. 1982. Roosting ecology of bats, p. 1–56. In: T. H. Kunz (ed.). Ecology of bats. Plenum Publishing Corporation, New York. MCCRACKEN, G. F., J. P. HAYES, J. CEVALLOS, S. Z. GUFFEY AND F. C. ROMERO. 1997. Observations on the distribution, ecology and behaviour of bats on the Galapagos Islands. J. Zool., 243:757–770. MENZEL, M. A., J. M. MENZEL, W. M. FORD, J. W. EDWARDS, T. C. CARTER AND J. B. CHURCHILL. 2001. Home range and habitat use of male Rafinesquii’s big-eared bats (Corynorhinus rafinesquii). Am. Midl. Nat., 145:402–408. MILLER, D. A. 2003. Species diversity, reproduction and sex ratios of bats in managed pine forests of Mississippi. Southeast. Nat., 2:59–72. ———, E. B. ARNETT AND M. J. LACKI. 2003. Habitat management for forest-roosting bats of North America: a critical review of habitat studies. Wildl. Soc. Bull., 31:30–44. MORRELL, T. E., M. J. RABE, J. C. DEVOS, JR., H. GREEN AND C. R. MILLER. 1999. Bats captured in two ponderosa pine habitats in north-central Arizona. Southwest. Nat., 44:501–506. NAMS, V. O. 2000. Locate II: user’s guide. Pacer Computer Software. Truro, Nova Scotia, Canada. PERKINS, C. J., G. A. HURST AND E. R. ROACH. 1988. Relative abundance of small mammals in young loblolly pine plantations, p. 589–591. In: Proc. 5th Biennial South. Silv. Res. Conf., USDA. Gen. Tech. Rep. SO-74. RACEY, P. A. 1988. Reproductive assessment in bats, p. 31–46. In: T. H. Kunz (ed.). Ecological and behavioral methods for the study of bats. Smithsonian Institution, Washington, D.C. SAS INSTITUTE. 2001. Version 8. SAS Institution, Inc., Cary, North Carolina. SEALANDER, J. A. AND G. A. HEIDT. 1990. Arkansas mammals. University of Arkansas Press, Fayetteville. 308 p. SEAMAN, D. E., J. J. MILLSPAUGH, B. J. KERNOHAN, G. C. BRUNDIGE, K. J. RAEDEKE AND R. A. GITZEN. 1999. Effects of sample size on kernel home range estimates. J. Wildl. Manage., 63:739–747. SHUMP, K. A., JR. AND A. U. SHUMP. 1982. Lasiurus borealis. Mammalian species. No. 183, Amer. Soc. Mamm., Lawrence, Kansas. SWIHART, R. K. AND N. A. SLADE. 1985. Influence of sampling interval on estimates of home-range size. J. Wildl. Manage., 49:1019–1025. THOMAS, D. W. 1988. The distribution of bats in different ages of douglas-fir forests. J. Wildl. Manage., 52:619–626. WEAR, D. N. AND J. G. GREIS. 2002. Southern forest resource assessment: summary report. USDA For. Serv. Gen. Tech. Rep. SRS-54. Asheville, North Carolina. 103 p. WELCH, L. D. 2003. Movements, foraging areas, habitat selection and roost site selection of red bats in an intensively managed pine forest in Mississippi. M.S. Thesis, Mississippi State University, Mississippi State. 92 p. ———, D. A. MILLER AND F. J. VILELLA. 2004. Selection of diurnal roost sites by red bats (Lasiurus borealis) in an intensively managed pine forest in Mississippi. For. Ecol. and Manage., 199:11–20. WHITE, G. C. AND R. A. GARROT. 1990. Analysis of wildlife radio-tracking data. Academic Press, Inc., San Diego, California. 383 p.

2005


417

WIGLEY, T. B., W. M. BAUGHMAN, M. E. DORCAS, J. A. GERWIN, J. W. GIBBONS, D. C. GUYNN, JR., R. A. LANCIA, Y. A. LEIDEN, M. S. MITCHELL AND K. R. RUSSELL. 2000. Contributions of intensively managed forests to the sustainability of wildlife communities in the South. Proc. of the Conf.: sustaining southern forests, the science of forest assessment. USDA For. Serv., South. For. Resour. Assess. http://www.srs.fs.fed.us/sustain/conf/abs/wigley.htm. 45 p. WILSON, M. D. AND B. D. WATTS. 2000. Breeding bird communities in pine plantations on the coastal plain of North Carolina. Chat., 64:1–14. WORTON, B. J. 1989. Kernel methods for estimating the utilization distribution in home range studies. Ecology, 70:164–168. ZAR, J. H. 1974. Biostatistical analysis, 4th ed. Prentice-Hall, New Jersey. 931 p. SUBMITTED 23 FEBRUARY 2004

ACCEPTED 30 JUNE 2004