Geoffrey R. Smith

Reproductive Ecology of the Painted Turtle (Chrysemys picta) in the Nebraska Sandhills and across Its Range

Female painted turtles in western Nebraska matured after 5-6 activity seasons at 160-165 mm carapace length. Annual adult survivorship was at least 91.5%, and some females apparently survive beyond 30 yr of age. Nesting was recorded from 19 May to 17 July, and its onset was inversely related to March-May temperatures. Internesting interval averaged 16.4 days and decreased through the nesting season. Females usually produced two clutches per season, but many produced three clutches, and two may have produced four clutches. Average annual clutch frequency was estimated at 2.78 per female. Egg size was correlated with female size. When standardized for body size, egg size was negatively correlated with body size and clutch size and varied across estimated clutch number (early season clutches having larger, more elongate eggs than later ones) but not among years. Egg size was not constrained by pelvic canal width. Clutch size averaged 13.9, was positively correlated with body size, and varied across estimated clutch number (later clutches being smaller than earlier clutches) as well as across years. Clutch mass increased with body size but remained constant as a proportion of spent female body mass (=RCM). RCM varied across clutch number within years (higher in earlier clutches) and across years (with a trend for higher RCM in years following a warmer Oct.). Actual annual clutch output in triple-nesting females averaged 42 eggs or 30.9% of spent female body mass. Across populations of painted turtles, body size is positively correlated with latitude and elevation and negatively correlated with average frost-free days and mean annual temperature. Clutch frequency remains one of the most elusive traits but seems to be inversely related to latitude and age at maturity and positively related to frost-free days. Both egg size and clutch size tend to vary with body size within and among populations, with clutch size varying the most. Presumably because of its correlation with body size, clutch size also varied with latitude, elevation, the inverse of frost-free days, and the inverse of mean annual temperature. Populations of small turtles (at lower latitudes and/or warmer climates) apparently produce the largest eggs possible within the constraints of their pelvic canal diameter, whereas no such constraint exists for larger-bodied populations at high latitudes. Selection is probably more intense on egg size than clutch size, and clutch size seems to have a much greater environmental component.

Behavioral responses of American toad and bullfrog tadpoles to the presence of cues from the invasive fish, Gambusia affinis

The introduction of non-native predators is thought to have important negative effects on native prey populations. The susceptibility of native prey to non-native or introduced predators may depend on their ability to respond appropriately to the presence of these non-native predators. We conducted a laboratory based behavioral experiment to examine the response of American toad (Bufo americanus) and bullfrog (Rana catesbeiana) tadpoles to the presence of cues from the introduced mosquitofish (Gambusia affinis), a potential tadpole predator. Neither the American toad tadpoles nor the bullfrog tadpoles responded behaviorally to the presence of mosquitofish cues. If tadpoles are unable to respond to the presence of mosquitofish cues appropriately, then their ability to avoid predation by mosquitofish may be compromised and this may contribute to the impacts of mosquitofish on some tadpole populations.

Acute effects of road de-icers on the tadpoles of three anurans

The application of road de-icing compounds during the winter has the potential to result in the contamination of nearby freshwater habitats and affect amphibians breeding in those habitats. We conducted a study of the effects of several de-icing and associated compounds (sodium chloride, magnesium chloride, calcium acetate, magnesium acetate, sodium ferrocyanide, and sodium formate) on the tadpoles of three species of anurans: African clawed frogs (Xenopus laevis), American toads (Bufo americanus), and green frogs (Rana clamitans). The survivorship of X. laevis tadpoles was negatively affected by MgCl2, but not by NaCl. The survivorship of R. clamitans tadpoles was negatively affected by both NaCl and MgCl2. The tadpoles of B. americanus were not affected by the concentrations of NaCl and MgCl2 used in this study. Our results suggest that contamination of freshwater habitats by de-icing and associated compounds could potentially adversely affect at least some anuran populations, but that this potential can vary from species to species, and from compound to compound.

Distribution and abundance of macroinvertebrates within two temporary ponds

We investigated the distributions of macroinvertebrates within two temporary ponds (Spring Peeper Pond and Taylor-Ochs Pond) in central Ohio and examined what environmental factors may be driving those distributions. We sampled macroinvertebrates in Spring Peeper Pond three times from May to July 2001, and Taylor-Ochs Pond two times from May to June 2001. Macroinvertebrate distributions were significantly aggregated on all sampling dates in both ponds. Bivalve abundance in Spring Peeper Pond was higher in shallower water. The distribution of bivalves in Taylor-Ochs Pond was not correlated with any variable we measured. Dragonfly nymph abundance in Taylor-Ochs Pond decreased between the first and second sampling dates, whereas in Spring Peeper Pond no factor examined was correlated with dragonfly nymph density. Snail densities in Spring Peeper Pond were negatively related to dissolved oxygen and depth. In Taylor-Ochs Pond, snail abundance was positively related to temperature. The densities of damselfly nymphs in Spring Peeper Pond were positively related to dissolved oxygen and depth and declined across the study. In Spring Peeper Pond, hemipteran densities were negatively related to depth and increased across the study. Damselfly nymphs and hemipterans were not common enough in Taylor-Ochs to analyze. In general, the abiotic and biotic factors we examined explained relatively little (<37% in all cases) of the within pond distribution of the macroinvertebrates in our two study ponds.

Temperature relationships in the high-altitude viviparous lizard, Sceloporus jarrovi

-The thermal ecology of Sceloporus jarrovi was studied in the Chiricahua Mountains of southeastern Arizona at different elevations and times of year. Mean body temperature (Tb) was 31.8 C (range 6.6-38.8 C). Mean air temperature (Ta) was 20.6 C (range 5.0-36.2 C). The slope of the regression of Tb on Ta was 0.37. Winter Tbs were lower than summer Tbs. Low elevation lizards had higher Tbs than high elevation lizards. Males and females had similar Tbs. Pregnant females had lower Tbs than nonpregnant females. Pregnant females also had a lower slope for the Tb on Ta regression than nonpregnant females. Body temperatures of pregnant females at early stages of pregnancy (November) were not significantly different from pregnant females at late stages of pregnancy (May). Sceloporus jarrovi maintained lower Tbs than the sympatric lizard Sceloporus scalaris. These two species have different Tb on Ta regressions.

Ecology of Xenosaurus grandis agrenon, a Knob-Scaled Lizard from Oaxaca, México

Abstract We studied the ecology of a population of the mountain knob-scaled lizard, Xenosaurus grandis agrenon, from Oaxaca, México. Males and females did not differ in body size (SVL), but males did have larger heads and hind limbs than females. Mean litter size was 3.2. Sex ratio did not differ from 1:1. All lizards were found associated with crevices. The size of the crevice (thickness and depth) increased with lizard SVL. Mean body temperature was 25.6°C. Body temperature was related to air and substrate temperature. Body temperature was influenced by the amount of cover, and the lizards body position in its crevice but not by sex, month, vegetation type, or any crevice characteristics. We compare the ecology of this population to that of other Xenosaurus.

Reproduction in females of three species of crevice-dwelling lizards (genus Xenosaurus) from Mexico

Registramos la reproducción de tres especies de las lagartijas de México (Xenosaurus grandis, X. newmanorum, y X. platyceps; Xenosauridae) para investigar si ellas comparte las características reproductivas de otras especies de morfología aplanada. El tamaño de puesta difirio entre las tres especies, pero la diferencias no podrían ser explicadas por las diferencias en tamaño corporal. El tamaño de la puesta estuvo influenciado por el tamaño de la hembra únicamente en X. grandis. La reproducción en X. grandis y X. newmanorum es estacional, con la copula ocurriendo aparentemente en el oto¤o y la gestacón durando entre 9 y 10 meses. Las hembras de X. grandis aparentemente se reproducen cada do años, mientras que las hembras de X. newmanorum y X. platyceps se reproducen cada año. Nuestras evidencias sugieren que la morfología aplanada no ha resultado en una limitación sobre el tamaño de la puesta en Xenosaurus, como esta lo ha sido para otras especies de lagartijas que viven en comisuras de roca. Sin embargo, la variación en la reproduccón entre especies de Xenosaurus permanece sin ser explicada. We recorded reproductive parameters of three species of lizard from Mexico (Xenosaurus grandis, X. newmanorum, and X. platyceps; Xenosauridae) to investigate if they share the reproductive characteristics of other species with flattened morphology. Litter sizes differed among the three species, but the differences could not be explained by differences in body size. Litter size was influenced by female body size only in X. grandis. Reproduction in X. grandis and X. newmanorum is seasonal, with mating apparently occurring in the fall and gestation lasting 9-10 months. Xenosaurus grandis females apparently reproduce every other year, whereas X. newmanorum and X. platyceps females reproduce every year. Our evidence suggests that the flattened morphology has not led to constraints on litter size in Xenosaurus as it has in other species of crevice-dwelling lizards. However, variation in reproduction among species of Xenosaurus remains unexplained.

Thermal ecology of Sceloporus virgatus from Southeastern Arizona, with comparison to Urosaurus ornatus

The thermal ecology of the striped plateau lizard, Sceloporus virgatus, was studied in the Chiricahua Mountains of southeastern Arizona. Body temperatures averaged 33.4 C (range 14.2-39.3), and air temperatures at the site of capture averaged 24.8 C (range 9.0-34.8). The slope of the regression of body temperature on air temperature was 0.40. Body temperatures did not differ for lizards caught in winter (October to April) and summer (May to September). Individuals using different substrates had different body temperatures, but air temperatures at the site of capture were not different. While males and females maintained the same body temperatures gravid females had lower body temperatures than non-gravid females. Sceloporus virgatus individuals maintain lower body temperatures than did sympatric individual Urosaurus ornatus despite the fact that their mean air temperatures at the site of capture did not differ significantly

Growth and reproduction in the mud turtle Kinosternon hirtipes in Chihuahua, México

-Growth and reproductive data from a single population of Kinosternon hirtipes in Chihuahua, Mexico are reported. Males grow faster and are larger than females by age five or younger. Females mature in six to eight years at 95-100 mm carapace length. Ovulation occurs from at least early May to late September. Given the lengthy reproductive season, evidence from multiple sets of corpora lutea and enlarged ovarian follicles suggests an annual production of four clutches. Egg width and mass correlate positively with body length and mass, and negatively with clutch size when the effects of carapace length are removed. Clutch size based on corpora lutea averages three eggs (range 1-6). Clutch size correlates positively with body length and mass. Relative clutch mass (clutch mass/body mass minus clutch mass) averages 7.1% and is independent of body size. Comparisions are made with other kinosternine turtles. . , i i iles

The roles of predator identity and group size in the antipredator responses of American toad {Bufo americanus) and bullfrog {Rana catesbeiana) tadpoles

Summary Prey must integrate several cues to assess predation risk and determine appropriate antipredator responses. Few studies on anuran tadpoles have simultaneously varied multiple cues related to predation risk. We examined how American toad (Bufo americanus) and bullfrog (Rana catesbeiana) tadpoles respond to predator identity (e.g., dytiscid beetle larvae or bluegill sunfish), group size, and, for American toads, tadpole size. American toads were less active in control and with bluegill, and higher with dytiscids. American toads did not alter habitat use with bluegill, but solitary tadpoles avoided vegetation when with dytiscids. American toads in pairs or groups of 8 used vegetation more than solitary tadpoles in the presence of dytiscids. Smaller American toad tadpoles were more active and used open water more than larger tadpoles. Bullfrogs were less active in the presence of either predator relative to the control. Bullfrogs did not adjust habitat use with dytiscids, but used vegetation less in the presence of bluegill. Bullfrogs in groups of 8 were more active than solitary tadpoles or tadpoles in pairs. Group size in bullfrogs affected the response to predator cues. In conclusion, the behavior of tadpoles responds to a variety of factors, including group size, predator cues, and tadpole size.