The Herpetofaunal Community of Temporary ponds in North Florida Sandhills: Species Composition, Temporal Use, and Management Implications1
C. Kenneth Dodd, Jr.2 and Bert G. Charest3
Abstract.Amphibians and reptiles use an isolated temporary wetland in a north Florida sandhills throughout the year despite variation in environmental conditions. Species composition and number of individuals varies seasonally and annually. Temporal variation in habitat use must be considered in managing small wetlands and assessing their importance to the herpetofaunal community.
The sandhills and xeric live oak her-petofauna of Florida is diverse and contains a number of endemic species. Whereas the terrestrial herpe-tofauna has been described for a few sandhills communities (Campbell and Christman 1982, Mushinsky 1985), there have been no long-term studies of the ecology of species using temporary ponds. For breeding amphibians, sandhills temporary ponds are often the only sources of water that are free of predatory fish and many larger predatory insects, and such ponds may be extremely important for amphibian reproductive success (Macan 1966, Sexton and Phillips 1986, Semlitsch 1987, Moler and Franz 1988). At the same time, the ephemeral nature of these breeding sites makes reproductive success uncertain and thus provides an opposing selective pressure for their use (Semlitsch 1987).
Since January 1985, we have been conducting studies on the herpetofaunal community at a temporary pond in a north-central Florida long-leaf pine-turkey oak ("high pine")
'Paper presented at symposium. Management of Amphibians. Reptiles, and Snail Mammals in North America. (Flagstaff. AZ. July 19-21. 1988).
}C. Kenneth Dodd. Jr. is Zoologist (Research). National Ecology Research Center. US. Fish and Wildlife Service. 412N.E. 16th Avenue, Room 250. Gainesville. FL 32601.
'Bert G. Charest is Biological Aid (Wild-e). National Ecology Research Center.
Fish and Wildlife Service. 412 N.E. 16th Avenue. Room 250. Gainesville. FL 32601.
sandhills. Little is known of the composition of such Florida herpetofaunal communities, although Moler and Franz (1988) reported 16 anuran species breeding in various types of wetlands surrounded by sandhills on the 3750 ha Katharine Ordway Pre-serve-Swisher Memorial Sanctuary in Putnam County. Nothing is known about movement patterns and activity cycles of the herpetofauna, or about the numbers of individuals breeding at such ponds and the numbers of offspring produced.
The purposes of our study are to gain insight into the structure of the herpetofaunal community using a temporary pond in a sandhills ecosystem, to assess variation in species composition and temporal use of the pond, and to gather basic biological information on the species that comprise the community. This paper presents findings based on two years of fieldwork of a projected five year study.
Breezeway Pond, a 0.16 ha isolated temporary pond in a shallow 1.3 ha basin on the Katharine Ordway Pre-serve-Swisher Memorial Sanctuary, Putnam County, Florida, was encircled with a 230 m drift fence (mean height = 36 cm above the substrate) following the general procedure of Gibbons and Semlitsch (1982), reviewed by Jones (1986a).
Buckets were spaced at 10 m intervals and paired on opposite sides of the fence, making 23 stations of two buckets each. Sloping covers were put over the buckets and wet sponges were placed in them to minimize exposure to direct rays of the sun and desiccation, respectively. As a result, mortality among captured animals was < 1.0% and was caused primarily by invertebrate predation (sjfiders, ants, centipedes, and beetles).
Breezeway Pond is located at an ecotone. To the immediate south and west, the predominant habitat is "high pine" sandhills dominated by longleaf pine (Pinus palustris), turkey oak (Quercus laevis) and wiregrass (Aristida stricta). A xeric hammock dominated by sand live oak (Q. gemi-mta) and laurel oak (Q. laurifolia) faces the north, while a small "Pani-cum meadow" dominated by maidencane (Panicum hetnitomon), lies to the east. The distance from the drift fence to6the nearest forested plant association is no more than about 50 m in any direction.
Buckets were checked 5 days per 0 week in the morning (beginning 0700-0900 h depending on season) from January 16 through April 12, 1985, and from October 1,1985, until September 30,1987. For purposes of discussion and analysis, a year refers to a 12-month period from October through the following September (e.g. 1986 = October 1985 through September 1986) because reproduc-
tion and metamorphosis generally cease in early autumn while winter breeding has yet to commence.
All reptiles and amphibians were measured in the field (snout-vent length, carapace and plastron length [for turtles], tail length [for snakes and glass lizards]), weighed and marked for future identification using a year code (e.g., 0022 identifies animals marked in 1986) or an individual identification number (all turtles, snakes, gopher frogs [Rana areolata], red-tailed skinks [Eumeces egregiusl, and ground skinks [Scin-cella lateralis]). Very small animals, mostly juvenile frogs and lizards, were not marked because of their extremely small toes.
Notes were recorded on tail regeneration and damage, breeding and hatchling coloration, and reproductive status. All animals, except lizards, were released on the opposite side of the fence from site of capture; lizards were released on the same side as captured. Weather conditions, rainfall, pond water level, and maximum and minimum air and water temperatures were recorded. These data are similar to those recorded in other long-term studies employing drift fences to study amphibian communities (Gibbons and Bennett 1974, Gibbons and Semlitsch 1982) and are vital to the inventory and management of ecological communities and individual species (Jones 1986b).
In this paper we concentrate our analyses on the two most commonly captured amphibians, the striped newt (Notophthalmus perstriatus), a species listed as of special concern in Florida (Christman and Means 1978), and the eastern narrow-mouthed toad (Gastrophryne carolinensis), a common Florida frog (Carr 1940).
We also divided the year into biweekly sampling periods and plotted the cumulative number of species captured versus sampling period. The three years were plotted separately. Data from October 1985 through September 1987 were treated
two ways: (1) as if sampling began in October, and (2) as if sampling began in April. This provided a between year comparison of how effective sampling for species numbers would be if sampling began in the autumn as opposed to the spring.
Variation in the overall biweekly capture of amphibians and reptiles between 1986 and 1987 was compared using a Chi-square contingency table. The Spearman Rank Correlation Matrix then was used to compare bucket capture frequency between first capture and recaptured individuals, in both 1986 and 1987, of G. carolinensis and N. perstriatus. Since there were no significant differences, captures and recaptures were combined in subsequent analyses.
We tested for within-year variation in capture frequency inside and outside the fence using a one sample Chi-square goodness of-fit-test. The Spearman Rank Correlation Matrix was again used to make the following comparisons: (1) a within year comparison of animals captured inside the fence with those captured outside the fence for both 1986 and 1987 [both species], (2) a comparison of juvenile with adult G. carolinensis in 1986, (3) a comparison of juvenile G. carolinensis inside and outside the fence, and (4) a between year comparison of animals captured per bucket inside or outside the fence [both species].
To determine if N. perstriatus and G. carolinensis preferentially oriented to or from one of the three habitat types surrounding the pond, data were collapsed and analyzed using a Kruskal-Wallis 1-way ANOVA. Buckets 1-3 and 21-23 faced a xeric hammock, 4-6 faced a small open field, and 7-20 faced sandhills, thus producing the three habitat categories.
Statistical analyses were carried out using the SAS program for
microcomputers (SAS Institute Inc 1985) or program ABSTAT version 4.09 (Anderson-Bell 1984). For all analyses, P < 0.05 was considered ir dicative of statistical significance.
Severe cold weather and a prolonged drought characterized the sampling period from January through April 1985. In Gainesville, 33 km west of Breezeway Pond, low temperatures reached -12 C and rainfall was 152.4 mm below normal for the three month period. Breezeway Pond was dry throughout this period. Summer rains filled the pond in mid-July, and water remained until December 16; maximum pond depth was 60 cm but declined steadily after September. Free water was present from January 10-February 3 and from March 14 to April 22,1986. The pond remained dry throughout the summer of 1986 despite summer thunderstorms and did not refill until February 24,1987. From then until June 20 (115 days), up to 60 cm of water filled the pond. On June 20, the pond dried and remained dry through September 30.
Thirty-nine species (7161 individual captures) used the pond or its periphery at some point during the 27 months that the traps were monitored (table 1). The amphibians captured most often were the winter/ spring breeding striped newt, Notophthalmus perstriatus, and the spring/ i summer breeding eastern narrow-mouthed toad, Gastrophryne carolinensis. Only one other salamander was collected at Breezeway Pond, the dwarf salamander, Eurycea quad-ridigitata. Fourteen species of frogs visited the pond, and six were present at virtually any time of the year: Acris gryllus, Bufo querckus, B. ter-
fgstris, G. carolinensis, Limnaoedus ocu-frfis, and Scaphiopus holbrooki. Adult flylafetnoralis and juvenile Rana
catesbeiana were caught mainly in the summer. Adult R. areolata were caught in the early spring as they
Table 1.Species and numbers of Individual amphibians and reptiles captured (first number) and recaptured (second number) at Breezeway Pond, January 1985 through September 1987. = very small Individuals not marked.
Species 1985 1985-1986 1986-1987 Total
(January- (October- (October-
April) September) September)
'Eurycea quadridigitata 5/0 10/0 8/0 23/0
Monophthalmus perstriatus 29/5 558/309 744/226 1331/540
'Acris gryllus 5/0 74/5 64/1 143/6
Bufo quercicus 1/0 111/31 96/50 208/81
Bufo terrestris 6/2 65/46 109/109 180/157
Eleutherodaciylus planirostris 0/0 0/0 2/0 2/0
'Gastrophryne carolinensis 2/0 1500/226 379/274 1881/500
Hyla chrysoscelis 0/0 1/0 0/0 1/0
Hyla femoralis 0/0 4/0 39/2 43/2
Hyla squirella 0/0 3/0 0/0 3/0
*Limnaoedus ocularis 14/0 20/0 49/0 83/0
Rana areolata 2/1 9/5 46/23 57/29
Rana catesbeiana 2/4 9/4 0/0 11/8
Rana grylio 1/0 0/0 5/0 6/0
Rana sphenocephala 0/0 5/0 15/2 20/2
Scaphiopus holbrooki 1/1 66/19 165/92 232/112
Apalone ferox 0/0 6/4 0/0 6/4
Deirochelys reticularia 0/0 2/0 0/0 2/0
Kinosternon subrubrum 9/0 7/0 11/4 27/4
Pseudemys Horidana 0/0 17/14 2/2 19/16
Cnemidophorus sexlineatus 18/7 140/135 122/115 280/257
'Eumeces egregius 14/2 54/8 30/4 98/14
Eumeces inexpectatus 0/0 0/0 1/0 1/0
'Ophisaurus ventralis 0/0 14/2 15/0 29/2
Sceloporus undulatus 4/0 7/2 2/0 13/2
'Scincella lateralis 23/0 217/2 207/2 447/4
Cemophora coccinea : VI 2/0 2/0 5/1
Coluber constrictor 2/0 7/0 8/8 17/8
Diadoph'is punctatus 0/0 2/0 2/2 4/2
Micrurus fulvius 0/0 6/0 8/0 14/0
Nerodiafasciata 3/0 4/1 13/1 20/2
Nerodia Horidana 1/0 6/1 4/0 11/1
Regina alleni 2/1 1/0 2/0 5/1
Seminatrix pygaea 59/14 18/10 13/11 90/35
Sistrurus miliarius 0/0 4/0 2/1 6/1
moved toward breeding ponds, and juvenile jR. areolata and R. sphenocephala were caught in late summer and early autumn presumably as they emigrated to terrestrial habitats.
The most commonly captured reptiles were the lizards Scincella lateralis, Cnemidophorus sexlineatus and Eumeces egregius, and the snake Seminatrix pygaea (table 1). Recent hatch-lings accounted for all individuals of the lizards Ophisaurus ventralis and most S. lateralis, as well as the snakes Coluber constrictor, Nerodia fasciata and Thamnophis sirtalis, and the turtles Pseudemys floridana and Kinosternon subrubrum. The only snake caught in substantial numbers was the swamp snake, S. pygaea, especially as they left the pond during the 1985 drought.
Cumulative Capture Rates
The rate at which species were captured varied between 1986 and 1987 (fig. 1). More species were captured at a faster rate in 1986 than in 1987 for sampling begun in October. However, the reverse was true for sampling begun in April. In autumn, the number of new species reached an asymptote after about six weeks of sampling in both years but at different levels (25 in 1986,23 in 1987). In spring, the capture of new species rose steadily both years; in 1986 it never leveled off whereas in 1987 it leveled off (at 31) only after four months of sampling. In 1985, the rate at which new species were observed rose rapidly throughout the period and was beginning to level off only when the observations were terminated.
In 1985, three months of sampling produced 25 of the 39 (64%) species now known to be present at Breezeway Pond. Corresponding percentages for other years and durations of sampling are as follows: 1986 6 months begun in October = 74%, 6 months begun in April = 77%, 12 months = 85%; 1987 6 months be-
gun in October = 59%, 6 months begun in April = 82%, 12 months = 87%.
Variation in Biweekly Capture
The numbers of amphibians and reptiles captured biweekly varied and was significantly different between 1986 and 1987 for both amphibians (X2 = 1366.46, 1 df, P < 0.001) and reptiles (X2 = 128.08, 1 df, P < 0.001). For amphibians, very few were caught from October 1986 through January 1987 compared with the same period in 1985-1986. There also were many fewer individuals caught during the summer of 1987 compared with 1986. This was due to a late summer drought which resulted in the complete drying of the pond with subsequent reproductive failure of G. carolinensis. Successful reproduction by this species in the summer of 1985 accounted for the large numbers of amphibians captured in 1986 (fig. 2). Even if juvenile narrow-mouthed toads are excluded (N = 690), there were still nearly 1000 more amphibians recorded in 1986 compared with 1987 (3425 in 1986, 2475 in 1987).
The numbers of reptiles recorded in and around Breezeway Pond were very similar between years, although there was enough variation to make the patterns significantly different. As might be expected, reptile activity decreased during the winter from late October through mid-March although some individuals were active year round (fig. 3). The peak in numbers in mid-July 1986 represents both a large number of species captured as well as an influx of hatchling S. lateralis.
Temporal Capture Variation: Notophthalmus perstriafus and Seminafrix pygaea
An example of annual variation in numbers of individuals and dates of
= S = *> i
O O A
Figure 1 .A comparison of the rate at which species were recorded tor sampling from January-April 1985 (1985), October 1985-Sepfember J986 (1986), and October 1986 through September 1987 (1987). For 1986 and 1987, the data were treated as if sampling began either in October or April.
Figure 2.Number of amphibians captured at Breezeway Pond in 1986 and 1987 by 2-week
o o o
8 8 8
Figure 3.Number of reptiles captured at Breezeway Pond in 1986 and 1987 by 2-week Intervals.
N0T0PHTHALMU3 PERSTRIATUS BREEZEWAY POND
* me n-j4
i* i if
figure 4.Comparison of the numbers of striped newts (Notophthalmus perstriatus) cap-JUred from January 16 through April 16, 1985-1987. The stars indicate days of > 10 mm rainfall.
capture is illustrated by comparing collecting data from 1985 through 1987 for striped newts, N. perstriatus (fig. 4), and swamp snakes, S. pygaea (fig. 5). From mid-January through mid-April, the numbers of newts captured varied from 34 in 1985 to 364 in 1986 and 449 in 1987. Most captures occurred from the first week of February through the latter part of March, and were associated with rainfall > 10 mm. Movements in 1985 occurred despite bitter cold and prolonged drought.
In contrast, striped swamp snakes did not leave the pond during the cold weather of 1985, but waited until temperatures moderated in early March (fig. 5). Unlike newts, however, they did not return in appreciable numbers later in 1986 or 1987 despite favorable habitat and climatic conditions.
Orientation and Movement Patterns: Gastrophryne carolinensis and Notophthalmus perstriatus
The frequency of bucket capture, both inside and outside the drift fence, varied significantly for both adult G. carolinensis and N. perstriatus in 1986 and 1987 (table 2). These data indicate non-random movement into and out of the pond. There was no significant correlation between inside and outside bucket capture frequency for G. carolinensis in 1986 (rt = -0.20, 22 df) or 1987 (rf = -0.25, 22 df). There was significant correlation between inside bucket captures between 1986 and 1987 (rs = 0.35, 22 df) but not between outside bucket captures between years (r = 0.06, 22 df). These results indicate that narrow-mouthed toads left the pond in similar directions but entered it from different directions.
Juvenile G. carolinensis entering and exiting Breezeway Pond showed distinct differences between capture frequency at different stations (X2 = 535.73, df = 22, P < 0.001). However,
SEMINATR1X PYQAEA BREEZEWAY POND
*- 188 N-2
I I I
Figure 5Comparison of the numbers of swamp snakes (Seminatrix pygaea) captured from January 16 through April 16,1985-1987. The stars indicate days of > 10 mm rainfall.
they showed no correlation with adult capture frequency per station (rs = 0.09,22 df). There also was no correlation in bucket capture frequencies for juveniles caught inside and outside the drift fence (ra = 0.26, 22 df). These data apply only to 1986 because no juveniles were observed in 1987.
For N. perstriatus, there was likewise no significant correlation in inside versus outside bucket capture frequency in 1986 (rs = 0.23,22 df) or 1987 (rs = 0.03, 22 df). Capture frequencies were compared outside the fence in 1986 versus 1987 (rs = 0.07, 22 df, P > 0.05) and inside the fence in 1986 versus 1987 (r, = 0.55,22 df, P < 0.01). As with Gastrophryne, these results suggest that newts were leaving the pond in similar directions between years, but that they were entering it from different directions.
Adult Gastrophryne did not move toward specific habitats in either 1986 (X2 = 2.62,2 df, P = 0.27) or 1987 (X2 = 0.32, 2 df, P = 0.85). On the other hand, juvenile narrow-mouthed toads moved toward the sandhills at a higher frequency than would be expected if movements were random (X2 = 13.31, 2 df, P = 0.001), but not toward the pond from any particular direction (X2 = 2.26,2 df, P = 0.32). Striped newts showed non-random movement in 1986 (X2 = 7.79, 2 df, P 0.02) toward the sandhills but in 1987 moved toward the Panicum meadow more often than would be expected by chance alone (X2 = 9.42, 2 df, P = 0.009). Movement in relation to nearby habitat is illustrated in figure 6.
Was Sampling Effective?
Although we caught 39 species in > 7000 captures, it is likely that more
species of amphibians and reptiles occasionally visit Breezeway Pond. Some species, such as the eastern coachwhip snake (Masticophis flagel-lum), Florida pine snake (Pituophis melanoleucus), and gopher tortoise (Gopherus polyphemus), are common
in adjacent sandhills but have not been observed in or near the pond. Large snakes (e.g., Pituophis, Masticophis) could easily go over the fence and thus avoid capture. The barking treefrog (Hyla gratiosa) bred in the pond before the initiation of our
Table 2.Is the frequency of bucket capture random inside and outside the drift fence? For all analyses, there were 23 stations and 22 df. A significant value indicates non-random movement.
Species Year Orientation P
Gastrophryne 1986 Inside 55.68 < 0.001
carolinensis 1986 Outside 81.25 < 0.001
1987 Inside 84.00 < 0.001
1987 Outside 100.69 < 0.001
Notophthalmus 1986 Inside 243.56 < 0.001
perstriatus 1986 Outside 93.44 < 0.001
1987 Inside 88.45 < 0.001
1987 Outside 145.48 < 0.001
(R. Franz, pers. comm.), but ^ have never captured it or heard it filing from the pond.
gome species, particularly ^frogs such as Hyla femoralis, fright be able to climb over the fence ,nd thus go undetected (Gibbons ind Semlitsch 1982). Newts (N. qiridescens) are known to scale drift fences (Semlitsch and Pechmann 1935) although we have riot observed fl,perstriatus doing so. We have ob-jjrved a substantial number of unmarked newts inside the drift fence even after two years of study, but we do not know if they were residents that were moving after remaining in the pond area for several years, or if they entered by crawling over or under the drift fence. Harris et al. (1988) noted that many adult N. viridescens burrowed into mud at the edge of North Carolina sandhills ponds as the ponds dried.
For these reasons, our data probably underrepresent both the number of species and individuals using the pond during the two years of observation. On the other hand, it is unlikely that some species (e.g., Bufo, Scaphiopus) are able to climb the fence. As such, capture results of these species may provide a reasonably accurate estimate of pond use.
GC 1986 JUV : LEAVING POND
GC 1986 ADULT
It is difficult to interpret data on activity patterns of species with only two years of data because there are many variables that influence activity tycles and the timing of reproduction. These variables, such as rainfall amount and distribution, maximum and minimum temperatures, and tydroperiod (Wiest 1982, Semlitsch 1985, Pechmann et al. 1988), vary daily, seasonally and yearly, and may affect different species in different ways. The subtle interaction of |hese parameters probably accounts 'Or the variation in activity patterns observed between years (Semlitsch l985, Semlitsch and Pechmann 1985).
Figure 6.Diagram illustrating the relationship between buckets, emigration from the pond, and nearby habitat for Gastrophryne carolinensis (GC) and Notophthalmus perstriatus (NP).
Amphibians breeding in sandhills ponds are faced with substantial uncertainty as to whether or not suitable conditions will prevail for reproduction. Breezeway Pond was chosen as the site for our study because it had consistently held water from the spring of 1983 through January 1985 (R. Franz, pers. comm.). Beginning in January, climatic conditions changed resulting in two years of drought with only sporadic free water. Temporary ponds may allow reproduction free of certain predators, but their use comes at the cost of reproductive uncertainty.
Amphibians are active during or immediately after periods of rainfall or high humidities. However, the interaction of moisture and temperature and how they affect condensation probably affects diel activity (Semlitsch and Pechmann 1985, Du-ellman and Trueb 1986, Pechmann and Semlitsch 1986) but also seasonal activity.
The extremely dry conditions at Breezeway Pond during the study makes it difficult to predict whether patterns observed in early 1985 and from late 1985 through late 1987 are "typical" for the amphibian community using the pond. Observations from other long-term studies of herpetofaunal communities suggest that there is wide variation in numbers of individuals at a site and in reproductive success from year to year (Gill 1978, Semlitsch 1983,1985,1987, Pechmann et al. 1988).
Because of their lack of dependence on standing water, temperature is probably more important than hy-droperiod in governing reptile daily and seasonal activity, at least for species in direct spatial proximity to the pond. However, reptile predators that opportunistically visit temporary ponds, such as garter snakes (Thamnophis sp.), might increase the number of visits and duration of stay if a sufficiently long hydroperiod allows amphibian reproduction to take place. Our data are insufficient as yet to answer this question.
Some individuals are active even during unfavorable environmental conditions of drought and unseason-ally cold temperatures. Amphibians and reptiles are generally, but not always inactive during cold or dry weather. For instance, Semlitsch (1983,1985) noted that mole salamanders (Ambystoma sp.) in South Carolina bred during the coldest but not necessarily the wettest months. He felt that most animals moved to breeding ponds at this time to allow sufficient time for larval development prior to pond drying (Semlitsch 1987). Such may not explain winter/ early spring breeding in N. perstriatus because the breeding period is extended (Bishop 1947) and larvae have been found from April through December (Christman and Means 1978). The larval period is unknown, but its duration is critical to successful reproduction in temporary sandhills ponds.
Individuals moving at times of unusually cold and dry weather may be searching for more favorable retreats or escaping adverse conditions. If the onset of migration (sensu Semlitsch 1985) commenced during unusually adverse conditions, and the unfavorable conditions extended for a long period of time, the population could be vulnerable to local extinction via mortality or emigration. Prolonged drought brought about the local extinction, via emigration, of the resident Seminatrix population.
Movement Patterns and Orientation
Because of the small size of Breezeway Pond, it is difficult to ascribe directed movements of individuals as migrating to, or originating from, a specific habitat type. Because the pond was located in an ecotone, an animal captured at buckets facing the interface between sandhills and xeric hammock could move in either direction once beyond the fence. Likewise, an animal originating from one habi-
tat type could be misclassified if ft moved a relatively short distance and fell into a bucket facing a different habitat type. The open field was also rather small and, although we did not feel comfortable assigning buckets 4-6 to sandhills or xeric ham-mock, it is likely that animals exiting or entering the pond through these buckets came from or went to one or the other habitat.
Given these qualifications, adult Gastrophryne did not exhibit habitat preferences, although juveniles left the pond primarily toward sandhills Gastrophryne are commonly recorded in sandhills (Carr 1940, Campbell and Christman 1982, Mushinsky 1985) and have been found in sandhills > 100 m from the nearest water source (Franz 1986, Dodd pers. obs.). Xeric hammock or sandhills apparently provide narrow-mouthed toads suitable cover and resources away from the breeding pond, but why juvenile Gastrophryne would njove toward sandhills is unknown.
Striped newts are most commonly found in flatwoods ponds in pine-palmetto habitats (Christman and Means 1978) as well as ponds in sandhills and scrub areas (Campbell and Christman 1982). To what extent they use sandhills habitats away from ponds is unknown. Carr (1940, reported as N. v. symmetrica) recorded efts in high and mesophytic hammocks in light, porous soil. However, striped newts at Breezeway Pond moved toward sandhills or meadow rather than hammock. Migration distances of striped newts are unknown although displaced N. viridescens can move 400 m through deciduous forest to return to a resident pond (Gill 1979). N. perstriatus probably can travel similar distances in its migrations.
The Florida sandhills are undergoing extensive habitat alteration because of rapid human population growth
nd associated development. In the 1970's, Auffenberg and Franz /1982) estimated that 70.6% of the Lnd pine-scrub oak, 57% of the long-leaf Pine'anc* 37.7% of the xeric ham-jriock communities had been de-Stroyed by forest plantation agricul-Hjfe and urbanization. In Putnam County' the site of our study, > 50% 0f the land area originally supporting juCh communities no longer does so. With projected human population Increases of more than 300% between 1972 and 2000 (Auffenberg and Franz 1982), there has been increasing content for the loss of sandhills habitats jn northern and central Florida. Extensive loss of habitat is occurring in other portions of the state and Southeast, such that only 14% of the long-leaf pine (Pinus palustris) forests remain from estimates of over 70 million acres that once comprised this community (Means and Grow 1985).
Because of habitat loss, amphibian and reptile populations dependent upon sandhills probably are declining. Many of the amphibians, such as the Florida gopher frog, Rana areolata tesopus, and the striped newt, N. perstriatus, are considered endangered, threatened, or rare (Fogarty 1978, Christman and Means 1978), yet there are few data on their life histories or population dynamics.
The paucity of information on species composition and population dynamics of amphibians and reptiles that use temporary ponds in xeric habitat masks the probable importance of such habitats. Variation in annual habitat use, both intraspecifi-cally and inter-specifically, appears to be considerable. Long-term ecological studies of the herpetofaunal community are needed to underhand the magnitude of such vari-, at!on and its potential significance.
Information on the biology of the species comprising the sandhills herpetofaunal community could be important in planning for the management of sandhills ecosystems by ^tate and Federal agencies. For instance, Florida Statutes Section
373.414 required Water Management Districts to adopt rules to establish specific permitting-criteria for small isolated wetlands, including size thresholds below which impacts on fish and wildlife habitats would not be considered. When these rules were adopted, almost no data were available on herpetofaunal communities on which to make recommendations for size threshold considerations. Lack of information led, in part, to variation among regulations adopted by the different Water Management Districts.
There is considerable interest among Florida biologists, conservationists, and land use planners in the concept of wildlife corridors to maintain biotic diversity (Harris 1985). Unfortunately, most discussions have centered on riparian habitats. The lack of data on sandhills habitat use, especially by candidate endangered or threatened species, could hamper the long-term survival of such species. Many sandhills species are likely dependent on small isolated wetlands for at least a portion of their life cycle. By focusing on riparian habitats, planners may be overlooking the importance of upland habitats and their associated small wetlands to the maintenance of biotic diversity.
The following are the most important implications of our study for the conservation and management of small isolated wetlands and their associated herpetofaunal communities in "high pine" xeric habitats in northern and central Florida. These should be kept in mind when evaluating impacts of habitat loss and planning assessment studies.
1. Many species use these habitats: some are permanent residents, some are migrants, and some wander through the area on an irregular basis. All pond-breeding species live in surrounding terrestrial habitats during the non-breeding season. Thus,
the pond and a portion of the terrestrial habitat are both critical to species persistence.
2. Such habitats are used year-round despite seemingly unfavorable periods of drought and cold weather.
3. Species composition varies within a year: some species are found only in one season, some predominate at one time but are found commonly at other times, some are very rarely observed.
4. Reproductive output among species varies considerably: in one year spring breeders may be successful, in other years summer breeders may be successful, in some years both probably produce young, in other years neither may successfully reproduce. The longer that studies are conducted, the greater is the likelihood that multiple patterns will emerge.
5. Activity patterns change seasonally and annually probably in response to environmental cues, particularly rainfall, temperature, and hydroperiod.
6. To determine the total number of species using such wetlands, spring and early summer sampling produces the best results, but single season or even yearly sampling will not catch all species.
7. Quick surveys underestimate both numbers of species and individuals, as well as annual variation, and thus underestimate the importance of temporary isolated wetlands in sandhills.
8. To adequately understand complex communities, long-term studies are absolutely essential for management and conservation.
We thank H. I. Kochman for advice on statistical analyses, and R. Ash-ton, R. Franz, J. Oldemeyer, J. H. K. Pechmann, R. Seigel and R. D. Semlitsch for their comments on the manuscript. R. L. Burke, K. M. Enge, and J. N. Stuart assisted with various phases of fieldwork.
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