Author Institution:  Dept of Zoology, Miami UniversityRelative clutch mass (RCM), the ratio of total mass of a clutch to the postpartum body mass of the female, is considered by many a life history trait that indirectly quantifies reproductive effort in snakes.   e Northern Watersnake (Nerodia sipedon sipedon) is one of the most abundant and widespread species of snake within Ohio. Litter sizes of N. s. sipedon have been reported to range between four and 99 and RCM values typically fall between 0.20 and 0.38. Two gravid N. s. sipedon were hand collected from Collins Creek (Butler County, Ohio) and maintained in the laboratory until parturition. Females gave birth to three and
six neonates with RCM values of 0.108 and 0.120, respectively.  The extremely small litter sizes and RCM values are, by far, the
lowest ever recorded for this species in Ohio and throughout their entire North American range.  This local population should be investigated further to determine if and how reproductive output is being depressed at Collins Creek

Gerald, Gary W.

Miskell, Courtney A.

The Ohio Journal of Science

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84 VOL.  107SMALL WATERSNAKE LITTER SIZES OHIO JOURNAL OF SCIENCE 85G. W. GERALD AND C. A. MISKELLBRIEF  NOTESmall Litter Sizes and Relative Clutch Mass of Northern Watersnakes (Nerodia sipedon sipedon) in Southwestern OhioGARY W. GERALD1 and COURTNEY A. MISKELL, Department of Zoology, Miami University, Oxford, OHAbstract.  Relative clutch mass (RCM), the ratio of total mass of a clutch to the postpartum body mass of the female, is considered by many a life history trait that indirectly quanti es reproductive e ort in snakes.   e Northern Watersnake (Nerodia sipedon sipedon) is one of the most abundant and widespread species of snake within Ohio.  Litter sizes of N. s. sipedon have been reported to range between four and 99 and RCM values typically fall between 0.20 and 0.38.  Two gravid N. s. sipedon were hand collected from Collins Creek (Butler County, Ohio) and maintained in the laboratory until parturition.  Females gave birth to three and six neonates with RCM values of 0.108 and 0.120, respectively.   e extremely small litter sizes and RCM values are, by far, the lowest ever recorded for this species in Ohio and throughout their entire North American range.   is local population should be investigated further to determine if and how reproductive output is being depressed at Collins Creek.OHIO J.SCI. 107 (4): 84-85, 20071Corresponding author: Gary W. Gerald, 212 Pearson Hall, Department of Zoology, Miami University, Oxford, OH 45056. Email: geraldgw@muohio.eduINTRODUCTIONRelative clutch mass (RCM), which is the ratio of the total mass of a clutch to the postpartum body mass of the female, is considered by many an important life history trait that indirectly quanti es reproductive e ort in reptiles (Seigel and Fitch 1984; Shine 1992).  Because a high RCM will likely reduce the locomotor abilities of females making them more vulnerable to predators, natural selection should favor individuals with an optimal RCM to maximize  tness.  Typical RCM values for snakes range from about 0.14 to 0.40 (Seigel and Fitch 1984).  RCM values tend to be lower in viviparous snakes because they must carry their young for a longer period of time (Shine and Schwartzkopf 1992).  Moreover, RCM values tend to be lower in species that frequently use aquatic locomotion since pregnancy disrupts stream-lining necessary for e  cient swimming (Shine 1988).  Ford and Seigel (1989) showed that clutch size and clutch mass are plastic in relation to resource levels (e.g. food intake) in the viviparous Checkered Gartersnake ( amnophis marcianus), with the reduction of RCM when resource levels are depressed.  Arguably one of Ohio’s most abundant snakes is the Northern Watersnake (Nerodia sipedon sipedon), being found in all 88 counties (Wynn and Moody 2006).   is viviparous species is found in a variety of lentic and lotic freshwater habitats across the state and feeds on a wide variety of prey (Gibbons and Dorcas 2004).   e mean litter size for N. s. sipedon is 26 and litter sizes ranging from four to 99 have been reported throughout their entire North American range (Ernst and Ernst 2003; Gibbons and Dorcas 2004).  Previous reports of RCM for N. s. sipedon range from 0.15 to 0.52 with typical values falling between 0.20 and 0.38 (Barron 1997).  Herein, we provide a report of extremely small litter sizes and RCM values for two female N. s. sipedon originating from a small stream in southwestern Ohio.MATERIALS AND METHODSTwo gravid females were hand collected less than 30 m from each other on 19 July 2006.  Both females were basking in low lying riparian vegetation overhanging Collins Creek, a third order Fathead minnows (Pimephales promelas) daily until parturition. Females and newborns were measured to the nearest 0.1 cm and weighed to the nearest 0.1 g.   is study was conducted in accordance with the Miami University Institutional Animal Care and Use Committee (Protocol # 634).RESULTSOne female (A) gave birth to six o spring (combined weight = 15.5 g) on 17 August 2006 and the second female (B) gave birth to three o spring (combined weight = 14.7 g) on 18 August 2006 (Table 1).  RCM values were 0.120 and 0.108 for females A and B, respectively.DISCUSSIONRelative clutch masses reported here are the smallest ever reported for Nerodia sipedon sipedon within Ohio and throughout its entire range, and are among the smallest reported for the entire genus Nerodia in North America.  Since o spring mass was very similar to those reported elsewhere for N. s. sipedon (Ernst and Ernst 2003; Gibbons and Dorcas 2004), the decrease in RCM is a direct result of the reduced litter sizes of both females.   e observed litter sizes are extremely low compared to those reported for this species throughout the rest of their geographic range and, to our knowledge, the litter size of three is the smallest ever reported for N. s. sipedon.   ese small litter sizes, and hence low RCM values, observed are likely due to decreased energy intake via consumption of low quality food or reduced food intake (Ford and Seigel 1989).  Since these females were captured in the same stream within 30 m of each other, we cannot rule out that these individuals are closely related.  However, the apparently high population density of Northern Watersnakes at Collins Creek (G.W. Gerald, personal observation) suggests that decreased litter sizes could be a result of intense intraspeci c competition for resources.   is population should be investigated further to determine whether or not reduced litter sizes are characteristic of this population and, if so, ascertain precisely the factors depressing the reproductive output of female N. s. sipedon in this particular stream.stream located in Butler County, Ohio (39º29’52”N; 84º43’57”W). Snakes were transported to the laboratory where they were fed Acknowledgments.  We would like to thank M. Kovach and C. Zematis for assistance in the  eld.LITERATURE CITEDBarron JN.  1997.  Condition-adjusted estimator of reproductive output in snakes. Copeia 1997(2):306-318.Ernst CH, Ernst EM.  2003.  Snakes of the United States and Canada. Washington D.C.:  Smithsonian Books. 668 p.Ford NB, Seigel RA.  1989.  Phenotypic plasticity in reproductive traits: evidence from a viviparous snake. Ecology 70(6):1768-1774.Gibbons JW, Dorcas ME.  2004.  North American watersnakes: a natural history. Norman: University of Oklahoma Press. 438 p.Seigel RA, Fitch HS.  1984.  Ecological patterns of relative clutch mass in snakes. Oecologia 61:293-301.Shine R.  1988.  Constraints on reproductive investment: a comparison between aquatic and terrestrial snakes. Evolution 42(1):17-27.Shine R.  1992.  Relative clutch mass and body shape in lizards and snakes: is reproductive investment constrained or optimized? Evolution 46(3):828-833.Shine R, Schwarzkopf L.  1992.   e evolution of reproductive e ort in lizards and snakes. Evolution 46(1):62-75.Wynn DE, Moody SM.  2006.  Ohio turtle, lizard, and snake atlas. Columbus: Ohio Biological Survey. 80 p.Table 1Summary of mass, snout-vent lengths (SVL), tail lengths, total lengths, and relative clutch mass (RCM) for two female Nerodia sipedon sipedon and their o spring.  Each individual o spring, which are denoted by a letter (indicating the mother) and number, are listed directly under the mother.Individual  Pre-birth mass (g) Post-birth mass (g)  SVL (cm)  Tail (cm)  Total (cm)  RCMFemale A          159.2          129.4        65.7      17.9     83.6  0.1198     A1              -              3.0        14.3        3.8     18.1      A2              -              3.0        14.5        3.7     18.2      A3              -              1.6        11.3        3.7     15.0      A4              -              3.1        15.0        4.1     19.1      A5              -              3.2        15.2        4.7     19.9      A6              -              1.6        12.4        3.7     16.1       Female B          161.0          135.7        59.1      13.3     72.4  0.1083     B1              -              4.8        17.2        6.0     23.2      B2              -              5.3        17.9        4.9     22.8      B3              -              4.6        16.0        5.8     21.8 84 VOL.  107SMALL WATERSNAKE LITTER SIZES OHIO JOURNAL OF SCIENCE 85G. W. GERALD AND C. A. MISKELLBRIEF  NOTESmall Litter Sizes and Relative Clutch Mass of Northern Watersnakes (Nerodia sipedon sipedon) in Southwestern OhioGARY W. GERALD1 and COURTNEY A. MISKELL, Department of Zoology, Miami University, Oxford, OHAbstract.  Relative clutch mass (RCM), the ratio of total mass of a clutch to the postpartum body mass of the female, is considered by many a life history trait that indirectly quanti es reproductive e ort in snakes.   e Northern Watersnake (Nerodia sipedon sipedon) is one of the most abundant and widespread species of snake within Ohio.  Litter sizes of N. s. sipedon have been reported to range between four and 99 and RCM values typically fall between 0.20 and 0.38.  Two gravid N. s. sipedon were hand collected from Collins Creek (Butler County, Ohio) and maintained in the laboratory until parturition.  Females gave birth to three and six neonates with RCM values of 0.108 and 0.120, respectively.   e extremely small litter sizes and RCM values are, by far, the lowest ever recorded for this species in Ohio and throughout their entire North American range.   is local population should be investigated further to determine if and how reproductive output is being depressed at Collins Creek.OHIO J.SCI. 107 (4): 84-85, 20071Corresponding author: Gary W. Gerald, 212 Pearson Hall, Department of Zoology, Miami University, Oxford, OH 45056. Email: geraldgw@muohio.eduINTRODUCTIONRelative clutch mass (RCM), which is the ratio of the total mass of a clutch to the postpartum body mass of the female, is considered by many an important life history trait that indirectly quanti es reproductive e ort in reptiles (Seigel and Fitch 1984; Shine 1992).  Because a high RCM will likely reduce the locomotor abilities of females making them more vulnerable to predators, natural selection should favor individuals with an optimal RCM to maximize  tness.  Typical RCM values for snakes range from about 0.14 to 0.40 (Seigel and Fitch 1984).  RCM values tend to be lower in viviparous snakes because they must carry their young for a longer period of time (Shine and Schwartzkopf 1992).  Moreover, RCM values tend to be lower in species that frequently use aquatic locomotion since pregnancy disrupts stream-lining necessary for e  cient swimming (Shine 1988).  Ford and Seigel (1989) showed that clutch size and clutch mass are plastic in relation to resource levels (e.g. food intake) in the viviparous Checkered Gartersnake ( amnophis marcianus), with the reduction of RCM when resource levels are depressed.  Arguably one of Ohio’s most abundant snakes is the Northern Watersnake (Nerodia sipedon sipedon), being found in all 88 counties (Wynn and Moody 2006).   is viviparous species is found in a variety of lentic and lotic freshwater habitats across the state and feeds on a wide variety of prey (Gibbons and Dorcas 2004).   e mean litter size for N. s. sipedon is 26 and litter sizes ranging from four to 99 have been reported throughout their entire North American range (Ernst and Ernst 2003; Gibbons and Dorcas 2004).  Previous reports of RCM for N. s. sipedon range from 0.15 to 0.52 with typical values falling between 0.20 and 0.38 (Barron 1997).  Herein, we provide a report of extremely small litter sizes and RCM values for two female N. s. sipedon originating from a small stream in southwestern Ohio.MATERIALS AND METHODSTwo gravid females were hand collected less than 30 m from each other on 19 July 2006.  Both females were basking in low lying riparian vegetation overhanging Collins Creek, a third order Fathead minnows (Pimephales promelas) daily until parturition. Females and newborns were measured to the nearest 0.1 cm and weighed to the nearest 0.1 g.   is study was conducted in accordance with the Miami University Institutional Animal Care and Use Committee (Protocol # 634).RESULTSOne female (A) gave birth to six o spring (combined weight = 15.5 g) on 17 August 2006 and the second female (B) gave birth to three o spring (combined weight = 14.7 g) on 18 August 2006 (Table 1).  RCM values were 0.120 and 0.108 for females A and B, respectively.DISCUSSIONRelative clutch masses reported here are the smallest ever reported for Nerodia sipedon sipedon within Ohio and throughout its entire range, and are among the smallest reported for the entire genus Nerodia in North America.  Since o spring mass was very similar to those reported elsewhere for N. s. sipedon (Ernst and Ernst 2003; Gibbons and Dorcas 2004), the decrease in RCM is a direct result of the reduced litter sizes of both females.   e observed litter sizes are extremely low compared to those reported for this species throughout the rest of their geographic range and, to our knowledge, the litter size of three is the smallest ever reported for N. s. sipedon.   ese small litter sizes, and hence low RCM values, observed are likely due to decreased energy intake via consumption of low quality food or reduced food intake (Ford and Seigel 1989).  Since these females were captured in the same stream within 30 m of each other, we cannot rule out that these individuals are closely related.  However, the apparently high population density of Northern Watersnakes at Collins Creek (G.W. Gerald, personal observation) suggests that decreased litter sizes could be a result of intense intraspeci c competition for resources.   is population should be investigated further to determine whether or not reduced litter sizes are characteristic of this population and, if so, ascertain precisely the factors depressing the reproductive output of female N. s. sipedon in this particular stream.stream located in Butler County, Ohio (39º29’52”N; 84º43’57”W). Snakes were transported to the laboratory where they were fed Acknowledgments.  We would like to thank M. Kovach and C. Zematis for assistance in the  eld.LITERATURE CITEDBarron JN.  1997.  Condition-adjusted estimator of reproductive output in snakes. Copeia 1997(2):306-318.Ernst CH, Ernst EM.  2003.  Snakes of the United States and Canada. Washington D.C.:  Smithsonian Books. 668 p.Ford NB, Seigel RA.  1989.  Phenotypic plasticity in reproductive traits: evidence from a viviparous snake. Ecology 70(6):1768-1774.Gibbons JW, Dorcas ME.  2004.  North American watersnakes: a natural history. Norman: University of Oklahoma Press. 438 p.Seigel RA, Fitch HS.  1984.  Ecological patterns of relative clutch mass in snakes. Oecologia 61:293-301.Shine R.  1988.  Constraints on reproductive investment: a comparison between aquatic and terrestrial snakes. Evolution 42(1):17-27.Shine R.  1992.  Relative clutch mass and body shape in lizards and snakes: is reproductive investment constrained or optimized? Evolution 46(3):828-833.Shine R, Schwarzkopf L.  1992.   e evolution of reproductive e ort in lizards and snakes. Evolution 46(1):62-75.Wynn DE, Moody SM.  2006.  Ohio turtle, lizard, and snake atlas. Columbus: Ohio Biological Survey. 80 p.Table 1Summary of mass, snout-vent lengths (SVL), tail lengths, total lengths, and relative clutch mass (RCM) for two female Nerodia sipedon sipedon and their o spring.  Each individual o spring, which are denoted by a letter (indicating the mother) and number, are listed directly under the mother.Individual  Pre-birth mass (g) Post-birth mass (g)  SVL (cm)  Tail (cm)  Total (cm)  RCMFemale A          159.2          129.4        65.7      17.9     83.6  0.1198     A1              -              3.0        14.3        3.8     18.1      A2              -              3.0        14.5        3.7     18.2      A3              -              1.6        11.3        3.7     15.0      A4              -              3.1        15.0        4.1     19.1      A5              -              3.2        15.2        4.7     19.9      A6              -              1.6        12.4        3.7     16.1       Female B          161.0          135.7        59.1      13.3     72.4  0.1083     B1              -              4.8        17.2        6.0     23.2      B2              -              5.3        17.9        4.9     22.8      B3              -              4.6        16.0        5.8     21.8 

Small Litter Sizes and Relative Clutch Mass of Northern Watersnakes (Nerodia sipedon sipedon) in Southwestern Ohio

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Small Litter Sizes and Relative Clutch Mass of Northern Watersnakes (Nerodia sipedon sipedon) in Southwestern Ohio

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