Breeding and recruitment phenology of amphibians in Missouri oak-hickory forests.
Many species of amphibians with complex life cycles use the same ponds for mating, reproduction and larval development. Competition for pond resources necessitates that species partition the aquatic habitat in space or time. Aquatic breeding habitats generally change over time, often seasonally, and amphibian species adjust the timing of reproductive activities to exploit these changing resources (Wilbur, 1980). The resulting differences in breeding phenologies presumably allow more species to coexist through reduced larval competition and predation.
Conditions in the aquatic habitat strongly influence length of the amphibian larval stage, which may last from weeks to years depending on the species (e.g., Werner, 1986; Alford and Harris, 1988). Although timing of and size at metamorphosis are flexible life history traits, minimum size and maximum length of the larval period are generally bounded for species (e.g., Wilbur and Collins, 1973; Smith, 1987; Alford and Harris, 1988). In harsh aquatic environments, larvae metamorphose quickly and at a small size due to rapid pond drying, high levels of competition or predation. Under favorable aquatic conditions, larvae may postpone metamorphosis and benefit from increased growth and large size at metamorphosis (Alford, 1999).
Although mechanisms influencing breeding patterns have been tested in experimental communities, few studies have reported the breeding phenology of natural amphibian communities (but see Paton et al., 2000; Paton and Crouch, 2002; Todd and Winne, 2006). Pond-breeding amphibians may be broadly classified as winter, spring, summer, or fall breeders. Factors such as rainfall and temperature are important constraints on the seasonal timing of reproduction (e.g., Semlitsch, 1985; Sexton et al., 1990; Redmer, 2002; Todd and Winne, 2006). Some studies have also examined the effects of timing of oviposition on larval performance through "priority effects" and how these community interactions potentially affect breeding and recruitment phenologies (Alford and Wilbur, 1985; Wilbur and Alford, 1985; Morin et al., 1990).
Knowledge of breeding phenologies is necessary for designing appropriate monitoring and inventory assessments and for conserving biodiversity of aquatic communities (Paton and Crouch, 2002). For example, land managers can schedule management activities, such as controlled burning and timber harvesting, to minimize the impacts on amphibians based on their phenologies. Although there is growing concern over the effect of global climate change on breeding phenologies and resulting species interactions (Beebee, 1995; Reading, 1998; Blaustein et al., 2001; Gibbs and Breisch, 2001), few detailed studies have examined phenology of multiple species at multiple locations. Having a baseline to compare phenologies in the future is essential when considering the impacts of global climate change on wildlife populations. Furthermore, the timing and length of the larval period is critical when evaluating hydroperiod, especially for design of restoration and mitigation wetlands.
Our objective was to quantify the breeding and recruitment phenology of pond-breeding amphibians in central Missouri oak-hickory forests. We discuss differences between two sites located approximately 100 km apart. Additionally, we discuss ecological processes potentially contributing to these differences and implications for managing isolated wetlands and the surrounding forests.
We studied amphibian breeding and recruitment phenologies from 2000-2004 at two sites in the Outer Ozark Border Subsection of central Missouri (Nigh and Schroeder, 2002). The first site was the University of Missouri's Thomas S. Baskett Wildlife Research and Education Area (hereafter Baskett), a 911-ha area located in Boone County, Missouri. We studied amphibian populations at two ponds year-round from Apr. 2000 to Sep. 2003. The ponds were constructed as wildlife ponds in the 1930s and are surrounded by forest consisting of oak (primarily Quercus alba and Q. rubra) and hickory (Carya spp.) with an understory of sugar maple (Acer saccharum) and dogwoods (Cornus spp.). Both ponds are less than 0.1 ha in size. One pond has a nearly permanent hydroperiod while the other dries in most summers.
The second site was the Missouri Department of Conservation's Daniel Boone Conservation Area (hereafter Boone) in Warren County, Missouri. The conservation area is 1424 ha dominated by oak-hickory forest (Quercus spp. and Carya spp.) and located approximately 100 km east of Baskett. Of the more than 40 ponds in Boone, we selected five ponds that were fishless, more than 200 m from the nearest public-use road and constructed 27-47 y ago. We monitored these ponds from 20 Feb. through 31 Oct. 2004. All five ponds are semi- to nearly- permanent, contained water for the duration of the study and ranged in size from 0.016 to 0.034 ha. We used constructed ponds because there are very few natural ponds in Missouri outside of the Missouri and Mississippi River floodplains. Most of the species breeding in these constructed ponds would likely have bred in floodplain ponds which have been drained or filled for agriculture. Additionally, they may have bred in small pools created by large tree blowdowns, which are likely less common now as forests have been harvested, leaving few large trees to create large blowdown ponds. Currently, most pond-breeding amphibians in central Missouri require fishless, constructed ponds due to the absence of suitable natural ponds.
To monitor amphibian populations and phenology, we completely encircled all seven ponds with a drift fence and pitfall traps. The drift fences were constructed of aluminum flashing buried approximately 30 cm into the ground and extending 60 cm above ground. At Baskett, pitfall traps consisted of number 10 coffee cans buried such that the top was flush with the ground. Traps were paired every 4.5 m along each side of the fence. At Boone, pitfall traps were located approximately every 3 m and we used plastic nursery pots for traps (23 cm diameter, 24 cm deep). At both sites, a wooden board was held 4 cm above each trap to reduce predation, and a moist sponge was placed in the bottom of each trap to reduce desiccation. Traps were checked every 1-3 d depending on weather conditions and time of year. We recorded date, species, sex, age class and migration direction for all individuals captured in our traps and we released them on the opposite side of the fence. Some species were also measured and marked (toe-clipped or pit-tagged) as part of population studies, but data on recaptures are not presented here.
The length of time that premetamorphic amphibians require aquatic habitat (from egg oviposition to metamorphosis) is important to consider when planning activities that may alter hydroperiods (i.e., timber harvest, impervious surfaces). We calculated the minimum value by subtracting the Julian date when 5% of the adult females had immigrated from the date when 5% of the metamorphs had emigrated from the ponds. The maximum is calculated from the dates of the 95th percentile of metamorph emigration minus the 5th percentile of female immigration (Paton and Crouch, 2002).
We recorded 13,521 adult and metamorph amphibian captures representing 11 species at the two ponds in Baskett during 4 y (Table 1). All 11 species occurred at both ponds. The western chorus frog (Pseudacris triseriata) was the only species not captured in all years. We captured seven species in sufficient abundance (>100 adult or metamorph captures) to examine phenologies.
We recorded 21,041 amphibian captures of 14 species at the five ponds in Boone during 1 y (Table 1). Nine of the species occurred at all ponds. We captured seven species in sufficient abundance (>100 adult or metamorph captures) to examine phenologies. Of the 15 species captured at Baskett and Boone, 10 were present at both sites and most species captured at only one site were found in small numbers. A notable exception was the ringed salamander (Ambystoma annulatum), which was among the most abundant species at Boone ponds but was absent from Baskett because the site is outside its geographic range.
The ringed salamander made up 45.0% of all captures at the five ponds in Boone. Ringed salamanders immigrated to breeding ponds from late Aug. through Oct.. Males and females immigrated simultaneously but the majority of males reached the pond prior to females (Table 2; Fig. 1). Following oviposition, the eggs hatched and the aquatic larvae over-wintered in the ponds. Most surviving offspring reached metamorphosis and emigrated in May, but metamorph emigration extended into Jul. (Fig. 1).
Salamanders comprised 85% and 96% of the adult captures and 67% and 62% of metamorph captures at Baskett and Boone, respectively. In addition to ringed salamanders, Boone ponds had large numbers of central newts (Notophthalmus viridescens louisianensis) and spotted salamanders (Ambystoma maculatum) (Table 1). Some ponds also had small numbers of marbled (Ambystoma opacum) and four-toed (Hemidactylium scutatum) salamanders (Table 1). Baskett is outside the current geographic range of marbled and four-toed salamanders, but spotted salamanders and central newts still comprised the majority of adult captures at Baskett ponds (Table 1). Although captured in small numbers, frogs constituted the majority of the amphibian species richness at both sites (Table 1).
There was considerable temporal partitioning of the breeding season among species. The majority of adult wood frogs (Rana sylvatica), spotted salamanders, central newts, spring peepers (Pseudacris crucifer), western chorus frogs, American toads (Bufo americanus), pickerel frogs (Rana palustris) and southern leopard frogs (Rana sphenocephala) immigrated to ponds between 5 Mar. and 30 Apr. at Boone and between 16 Mar. and 27 May at Baskett (Table 2; Fig. 2). The only species with complete overlap in breeding were wood frogs and spotted salamanders at Boone and spring peepers and pickerel frogs at Baskett (Table 2). Central newts had substantial overlap with spotted salamanders and wood frogs, but were also captured in significant numbers during the fall, especially at Boone (Fig. 1). The southern leopard frog was the only species to have a bimodal annual breeding distribution, with immigration and observed oviposition documented from Mar. through Apr. and again from Aug. through Oct. (Fig. 1).
Ninety-percent of metamorphs emerged between 11 May and 25 Oct. at Boone and between 25 May and 16 Oct. at Baskett. At Boone, ringed salamanders were the first to emigrate with the majority leaving the ponds by 25 May. Spotted salamander metamorph emigration began immediately following ringed salamander emigration and lasted through Nov. (Fig. 1). Thus, peak spotted salamander metamorph emergence was later at Boone than at Baskett (Table 2; Fig. 1). Similar to spotted salamanders, central newt metamorphs tended to emigrate 2-3 wk later at Boone ponds than from Baskett ponds (Table 2). However, in the case of central newts, the number of days from female immigration until metamorph emigration was similar at the two sites (Table 2). Spring peeper metamorphs emigrated from late-May through July. Metamorphs emigrated earlier and after fewer days at the Baskett ponds than at the Boone ponds (Table 2).
[FIGURE 1 OMITTED]
American toads had the shortest time from adult immigration to metamorph emigration. Metamorph emergence occurred between Jul, and Sep., 60-112 d after females entered the ponds (Table 2). We were not able to determine the length of time from female emigration until metamorph emigration for green frogs and southern leopard frogs because an unknown number of tadpoles overwintered in the ponds prior to metamorphosis.
Additionally, our drift fences were not completely effective at capturing adult green frogs (Rana clamitans), southern leopard frogs, bullfrogs (Rana catesbeiana), gray treefrogs (Hyla versicolor), spring peepers, western chorus frogs or northern cricket frogs (Acris crepitans). Nor were fences completely effective at capturing metamorphs of the family Hylidae including cricket frogs, spring peepers, chorus frogs and gray treefrogs. Bullfrogs were uncommon in our ponds, whereas cricket frogs and gray treefrogs were observed in large numbers despite avoiding our traps. In separate studies, gray treefrogs in Boone were found to breed from late-Apr, through Jun. and metamorphs emerged in Jul. to early-Sep. (Hocking and Semlitsch, 2007). At Baskett, breeding occurred from mid-May to mid-Jun, in 2003 and 2004, with metamorph emergence from early-Jul, through Sep. (Johnson, 2005).
Small, isolated wetlands within contiguous forest are important for maintaining biological diversity. We found that ponds in central Missouri oak-hickory forests support a total of 15 species of pond-breeding amphibians, with up to 14 species using a single pond during a year. Species richness was greater than reported in Paton and Crouch (2002) for ponds in Rhode Island, despite having similar breeding phenologies and growing seasons. They found 10 species among the seven ponds studied (Paton and Crouch, 2002) with as many as nine species using a single pond (Paton et al., 2000). Another study in the northeastern U.S. (New Hampshire), found nine species in 42 wetlands with as many as seven in a single wetland (Babbitt et al., 2003). In the southeastern U.S., as many as 27 species of amphibians have been documented at a single wetland (Semlitsch et al., 1996). Other studies in the southeast have also found high species richness (16-22 species in Semlitsch and Bodie, 1998; 24 in Gibbons et al., 2007). The species richness in our study was therefore intermediate between that of the northeast and southeast U.S. and slightly higher than other studies in the midwestern U.S (Upper Midwest: 11 species in Evrard and Hoffman, 2000; Indiana: 10 species in Brodman et al., 2006; Illinois: 10 species in Walston and Mullin, 2007).
The ponds we studied were dominated by salamanders in abundance but supported higher species richness of frogs (Table 1). While drift fences with pitfall traps are more effective for capturing salamanders than anurans (Todd et al., 2007), we observed relatively few anurans in nearby ponds without fences with the exception of Hyla versicolor, which were still an order of magnitude less abundant than caudates (Hocking and Semlitsch, 2007). We suggest that the ponds we studied are dominated by salamanders, but relative abundances captured are skewed by trap bias. Mark-recapture studies with additional trapping techniques will be necessary to accurately determine the population sizes and relative abundances of all species.
[FIGURE 2 OMITTED]
Although most frog and salamander species at our sites are considered spring breeders, there was substantial temporal partitioning in pond-use among species. As found in previous studies, the order of metamorph emigration does not strictly correspond to the order of adult emigration among species (Paton et al., 2000; Paton and Crouch, 2002). For example, although spring peepers bred slightly later than spotted salamanders, spring peeper metamorphs emerged before spotted salamanders due to differences in the length of the larval period (Table 2). Spring peepers and American toads have relatively short larval periods, whereas central newts, ringed salamanders, green frogs and bullfrogs have long larval periods.
Additionally, despite being conducted in a different region of the country and at different latitudes, the timing of adult breeding migrations at our sites is remarkably similar those reported for Rhode Island by Paton et al. (2000) and Paton and Crouch (2002). This similarity in amphibian phenology can potentially be explained by annual temperatures and length of the growing season. For example, Missouri and Rhode Island fall within the US Department of Agriculture plant hardiness zones 5b and 6a, respectively (Cathey, 1990). Timing of metamorph emigration at our sites was also remarkably similar to emigration in Massachusetts (Timm et al., 2007).
Another unexpected result was the difference in central newt captures among Baskett and Boone sites (Fig. 1). At the Boone ponds, adult newts were observed moving into and out of the pond in the fall but this phenomenon was never observed at Baskett. Many individuals moving in both directions had morphologies (i.e., laterally compressed tails) suggesting the newts were making frequent, short forays into the terrestrial habitat and intersecting the drift fence. We hypothesize that these migrations may only have occurred at Boone sites due to differences in aquatic food resources and individuals may have been moving into the terrestrial habitat to forage, however, many newts were observed over-wintering in all seven of the ponds. Future research should examine the duration, distance and newt behavior during these fall movements.
Similarly, spotted salamanders exhibited large variability in the duration of their breeding through metamorphosis (112-223 d) and this variation may result from differences in resource availability, thereby altering the length of the larval period. Intraspecific competition among larvae changes as metamorphs emerge and food resources also change through the seasons (Wilbur and Alford, 1985; Morin, 1987; Morin et al., 1990; Ryan and Plague, 2004). Additionally, spatial and temporal differences in pond hydroperiods may help maintain variation in length of the larval period. From the perspective of emigrating and dispersing metamorphs, seasonal climatic factors may influence the timing of metamorphosis. Early metamorphs may benefit from late-spring rains while later emerging metamorphs might benefit by emigrating during cool fall rain events, again maintaining variation in the larval period (Todd and Winne, 2006).
Despite temporal partitioning of resources, interspecific interactions influenced recruitment phenology in our study. We hypothesize that the presence of ringed salamanders caused spotted salamander metamorphs to emerge later in the season and after a longer larval period. We propose two possible explanations. First, spotted salamander larvae may have reduced their activity in the presence of larger ringed salamander larvae, which prey upon spotted salamander larvae (DJH, pers. obs.). The reduction in activity may have reduced foraging opportunities and therefore slowed the growth rates of spotted salamander larvae. Alternatively, the longer larval period may have been due to competition for common resources. Fall-breeding salamanders gain a size advantage over their spring-breeding congeners, which may give them a competitive advantage (but see Stenhouse et aL, 1983). The potential influence of ringed salamanders as an abundant predator in pond communities warrants further examination.
The timing of pond drying and length of the hydroperiod are important factors controlling pond communities and phenologies (e.g., Pechmann et al., 1989; Skelly, 2001; Babbitt et al., 2003). In addition to ringed salamanders, bullfrogs, green frogs, and the fall-breeding cohort of leopard frogs produce tadpoles that typically overwintered in our ponds prior to metamorphosis in the spring. These species take advantage of the relative permanence of man-made ponds in central Missouri. With large-scale land alteration from agriculture, timber harvest and development, these man-made ponds are the primary breeding source for many species of amphibians in this region of the country (Knutson et al., 2004). In Missouri, many of the protected amphibian breeding sites in the state were created on Missouri Department of Conservation land and have permanent or semi-permanent hydroperiods (Shulse and Semlitsch, unpubl.). Species with relatively long larval periods that overwinter in ponds have an advantage in ponds with predictably long hydroperiods and no fish.
Species that are greatly affected by high levels of competition or predation often have short larval periods and thus oviposit in ponds with short hydroperiods. Short hydroperiods prevent the accumulation of competitors and aquatic predators (Wilbur, 1987; Skelly, 2001; Babbitt et al., 2003; Baber et al., 2004). In the relatively permanent ponds we studied, however, salamanders comprised the majority of adult and metamorph amphibian captures. Newts and larval ambystomatid salamanders are often important predators in these aquatic communities (Wilbur, 1972; Caldwell et al., 1980; Morin, 1983). Thus, we assume that salamander predators reduced the recruitment of species such as the American toad, spring peeper, pickerel frog, southern leopard frog, western chorus frog and wood frog. Although anurans could potentially alter their breeding phenology to reduce salamander predation on their offspring, the abundance of salamander predators during a large part of the year (i.e., both fall- and spring-breeding species and adult newts) at our sites probably precludes this tactic. Future studies might benefit by experimentally excluding salamanders to examine changes in breeding phenology, length of the larval period and subsequent success of anuran populations.
Constructing ponds with short hydroperiods may be important for the conservation of anuran species in our region, especially a Missouri species of concern like the wood frog. With the increased use of restoration to mitigate for wetland loss and the general increase in concern for biodiversity, considering hydroperiod and amphibian reproductive phenology when designing ponds is essential for amphibian conservation (e.g., Lehtinen and Galatowitsch, 2001; Pechmann et al., 2001; DiMauro and Hunter Jr., 2002; Petranka et al., 2003; Porej and Hetherington, 2005). For our salamander community, particularly the ringed salamander, ponds lacking fish with a semi-permanent to permanent hydroperiod provide ideal breeding habitat (Porej and Hetherington, 2005). Ponds with a long hydroperiod also benefited green frogs. American toads, spring peepers and wood frogs had the shortest larval period and may, therefore, benefit from a short hydroperiod. American toads only need ponds to hold water from Apr. through Aug., while spring peepers and wood frogs need ponds to hold water from Feb. through Jun.. However, considering how the breeding phenology of anurans might differ in the absence of other species, especially salamander predators, is important when creating wetland habitat. In Missouri, ponds that are dry from Aug. to Nov. might be ideal for many species of frogs that suffer from predation in ponds with long hydroperiods. Overall, community interactions suggest that a matrix of ponds with varying hydroperiods is probably best for maintaining maximum species richness at the landscape scale (Semlitsch, 2000).
Finally, amphibians play an important role in aquatic and forest ecosystems (e.g., Burton and Likens, 1975; Beard et al., 2002; Davic and Welsh, 2004; Regester et al., 2006). Given the importance of amphibians to the ecosystem, land managers conducting management activities that disturb habitat surrounding ponds should account for amphibian reproductive phenologies during the planning stage. Terrestrial management activities such as burning, mowing and timber harvest should be avoided near ponds (within several hundred meters; see Semlitsch and Bodie, 2003; Rittenhouse and Semlitsch, 2007) during peak amphibian migrations, because species such as wood frogs, spotted salamanders and ringed salamanders migrate en masse during the peak of breeding. During this peak, a large portion of the population is susceptible to even localized disturbances. We suggest concentrating management activities with high levels of disturbance or traffic in Nov. through early Feb. (Fig. 2). Additional activities could potentially be conducted in Jun.-Aug. during dry periods when amphibian movements are curtailed (Todd and Winne, 2006). While call surveys and other less intensive methods may be used to monitor breeding phenologies, detailed breeding phenologies reported here provide baseline information for the conservation and management of amphibian populations in Missouri, especially in light of expected alterations due to climate change.
Acknowledgments.--We would like to thank K. Aldeman, T. Altnether, S. Altnether, S. Crouch, M. Doyle, C. R. Mank, J. Deters, N. Mills, B. Williams, S. James, G. Johnson, D. Johnson, B. Maltais, C. Rittenhouse, D. Patrick, S. Spears and Z. Slinker for help with field work and data collection. Earlier drafts of this manuscript were improved by the insightful comments of B. Todd, L. Hocking and three anonymous reviewers. We appreciate the support provided by the Missouri Department of Conservation with special thanks to J. Briggler and G. Raeker and to J. Millspaugh and the University of Missouri Department of Fisheries and Wildlife for access to the Baskett sites. This research was supported through grants from the U. S. Geological Survey 01CRAG0007 and the National Science Foundation DEB-0239943. D. Hocking, E. Harper and C. Conner were supported through Life Sciences Fellowships provided by the University of Missouri.
SUBMITTED 7 JULY 2007 ACCEPTED 11 DECEMBER 2007
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DANIEL J. HOCKING, (1) TRACYA. G. RITTENHOUSE, BETSIE B. ROTHERMEL, (2) JARRETT R. JOHNSON, (3) CHRISTOPHER A. CONNER, ELIZABETH B. HARPER (4) AND RAYMOND D. SEMLITSCH
Division of Biological Sciences, University of Missouri, Columbia 65211
(1) Corresponding author present address: University of New Hampshire, 215 James Hall, Durham 03824; e-mail: firstname.lastname@example.org
(2) Present address: The Center of Excellence for Field Biology, P.O. Box 4718, Austin Peay State University, Clarksville, Tennessee 37044
(3) Present address: Section of Evolution and Ecology, University of California, Davis 95616
(4) Present address: State University of New York College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse 13210
TABLE 1.--The mean number of captures per pond per year for all pond-breeding amphibian species (SE). Data at the two Baskett ponds were collected from 2000-2003. Data for the five Boone ponds were collected in 2004 Baskett Species Adults Metamorphs Caudata Ambystoma annulatum * * Ambystoma mwculatum 695 (202) 540 (279) Ambystoma opacum * * Hemidactylium scutatum * * Notophthalmus viridescens 97 (37.7) 193 (165) Anura Acris rupitans 2 (1.1) 0 (0.5) Bufo americanus 14 (8.1) 5 (5.5) Hyla versicolor 4 (2.5) 2 (1.1) Pseudacris cruaifer 43 (28.3) 1 (0.9) Pseudacris triseriata 0 (0.2) 2 (2.4) Rana catesbeiana 2 (1.4) 5 (3.6) Rana clamitans 18 (7.6) 255 (138) Rana palustris 18 (12.3) 5 (4.2) Rana sphenocephala 4 (1.0) 22 (20.9) Rana sylvatica * * Boone Species Adults Metamorphs Caudata Ambystoma annulatum 1756 (392) 139 (66.5) Ambystoma mwculatum 1318 (208) 269 (96.3) Ambystoma opacum 8 (3.2) 0 (0.2) Hemidactylium scutatum 4 (1.5) 2 (1.2) Notophthalmus viridescens 244 (63.8) 56 (32.4) Anura Acris rupitans 2 (1.5) 2 (1.8) Bufo americanus 33 (19.6) 0 (0.2) Hyla versicolor 7 (1.9) 7 (3.8) Pseudacris cruaifer 22 (6.1) 4 (2.4) Pseudacris triseriata 0 0 Rana catesbeiana 3 (0.9) 0 (0.2) Rana clamitans 44 (6.0) 234 (88.6) Rana palustris 6 (4.6) 0 Rana sphenocephala 1 (0.4) 0 Rana sylvatica 7 (3.3) 40 (38.7) * Baskett was outside the geographic range of these species TABLE 2.--Cumulative percent of individuals immigrating and emigrating from the ponds at the Boone and Baskett areas in central Missouri. Minimum days in the pond was calculated by subtracting the Julian date when 5% of females had immigrated from the date when 5% of the metamorphs had emigrated. Maximum days in the pond was calculated by subtracting the 5th percentile of female immigration from the 95th percentile of metamorph emigration Adult immigration Species sex n 5% Daniel Boone Conservation Area Ambystoma annulatum M 2904 20-Aug F 1569 22-Aug Ambystoma maculatum M 2249 5-Mar F 1182 4-Mar Bufo americanus M 59 25-Mar F 27 25-Mar Pseudacris crucifer M 27 3-Mar F 34 4-Mar Rana clamitans M 54 21-Apr F 56 1-Mav Rana sylvatica M 12 29-Feb F 11 4-Mar Notophthalmus viridescens M 397 24-Feb F 403 1-Mar Thomas S. Baskett Wildlife Research & Education Area Ambystoma maculatum M 1665 14-Feb F 1186 24-Feb Bufo americanus M 29 11-May F 21 7-May Pseudacris crucifer M 59 8-Mar F 58 5-Mar Rana clamitans M 29 11-Apr F 30 13-Apr Rana palustris M 84 13-Mar F 34 9-Mar Rana sphenocephala M 14 6-Mar F 11 9-Mar Notophthalmus viridescens M 244 14-Feb F 303 14-Feb Adult immigration Species sex 50% 95% Daniel Boone Conservation Area Ambystoma annulatum M 30-Aug 3-Oct F 17-Sep 9-Oct Ambystoma maculatum M 5-Mar 25-Mar F 11-Mar 25-Mar Bufo americanus M 25-Apr 11-May F 30-Apr 15-May Pseudacris crucifer M 9-Apr 21-Apr F 17-Apr 21-Apr Rana clamitans M 8-Jun 27-Oct F 22-Jun 23-Oct Rana sylvatica M 4-Mar 7-Mar F 5-Mar 24-Mar Notophthalmus viridescens M 4-Mar 23-Oct F 5-Mar 21-Oct Thomas S. Baskett Wildlife Research & Education Area Ambystoma maculatum M 9-Mar 20-Mar F 16-Mar 3-Apr Bufo americanus M 27-May 28-Sep F 27-May 8-Sep Pseudacris crucifer M 4-Apr 17-Apr F 4-Apr 14-Apr Rana clamitans M 2-Jul 22-Oct F 22-Jun 19-Oct Rana palustris M 3-Apr 27-Apr F 3-Apr 4-May Rana sphenocephala M 5-Apr 1-Oct F 24-Apr 22-Oct Notophthalmus viridescens M 16-Mar 10-Nov F 16-Mar 22-Oct Adult Metamorph immigration emigration Species sex n 5% Daniel Boone Conservation Area Ambystoma annulatum M F 697 11-May Ambystoma maculatum M F 1343 6-Jul Bufo americanus M F 1 Pseudacris crucifer M F 21 10-Jun Rana clamitans M F 1169 31-May Rana sylvatica M F 202 9-Jun Notophthalmus viridescens M F 278 8-Aug Thomas S. Baskett Wildlife Research & Education Area Ambystoma maculatum M F 3647 16-Jun Bufo americanus M F 38 6-Jul Pseudacris crucifer M F 9 28-May Rana clamitans M F 2037 25-May Rana palustris M F 39 12-Jul Rana sphenocephala M F 172 12-Jul Notophthalmus viridescens M F 1545 24-Ju1 Metamorph emigration Species sex 50% 95% Daniel Boone Conservation Area Ambystoma annulatum M F 25-May 2-Jul Ambystoma maculatum M F 20-Aug 13-Oct Bufo americanus M F Pseudacris crucifer M F 22-Jun 20-Jul Rana clamitans M F 20-Jul 21-Oct Rana sylvatica M F 10-Jun 16-Jun Notophthalmus viridescens M F 17-Sep 25-Oct Thomas S. Baskett Wildlife Research & Education Area Ambystoma maculatum M F 5-Aug 24-Sep Bufo americanus M F 14-Jul 27-Aug Pseudacris crucifer M F 4-Jun 19-Jun Rana clamitans M F 13-Jun 5-Oct Rana palustris M F 28-Jul 13-Aug Rana sphenocephala M F 29-Aug 30-Sep Notophthalmus viridescens M F 24-Aug 16-Oct Days in pond Species sex minimum maximum Daniel Boone Conservation Area Ambystoma annulatum M F 262 314 Ambystoma maculatum M F 124 223 Bufo americanus M F Pseudacris crucifer M F 98 138 Rana clamitans M F Rana sylvatica M F 97 104 Notophthalmus viridescens M F 160 238 Thomas S. Baskett Wildlife Research & Education Area Ambystoma maculatum M F 112 212 Bufo americanus M F 60 112 Pseudacris crucifer M F 84 106 Rana clamitans M F Rana palustris M F 125 157 Rana sphenocephala M F Notophthalmus viridescens M F 160 244 * Days in pond not calculated because an unknown portion overwinter as larvae
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|Author:||Hocking, Daniel J.; Rittenhouse, Tracy A.G.; Rothermel, Betsie B.; Johnson, Jarrett R.; Conner, Chri|
|Publication:||The American Midland Naturalist|
|Date:||Jul 1, 2008|
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