Francis L. Rose's research while affiliated with Texas State University and other places

We combined three separate sequential annual data sets (2008–2010) to document general phenology of nesting seasons, reproductive frequency, and interclutch intervals (ICIs) of female Pseudemys texana (Texas River Cooter) and Trachemys scripta (Red-eared Sliders) occupying a spring system in Hays, County, Texas. Detection of gravid females was done through frequent monitoring of nesting areas over three entire nesting seasons. Of the 108 Pseudemys texana that nested in the first year, 54 (50%) also nested in two subsequent years. Of the 65 Trachemys scripta that nested in the first year, only 13 (20%) nested in all three years. Percent of females that nested only in the first year was 10% and 19% for P. texana and T. scripta, respectively. Individuals that nested only once in a season, did so over all days in a season. Multiple clutching within a season was observed for both species. Within year ICIs of females was approximately 30 days for both species and only about 30% of both species nested.

Knowledge of somatic growth rates is important for acquiring information on life-history traits and population demography. Estimating growth rates for long-lived organisms, such as turtles, is challenging because it requires long sampling times for adequate growth rate estimation. Within the same species, growth can vary among populations due to variation in latitude, environmental conditions, diet, competition, genetics, and timing of sexual maturity. Here, we studied the somatic growth rates of male and female Common Snapping Turtles (Chelydra serpentina) from Spring Lake, Hays County, Texas, USA. We applied the Wang's modified von Bertalanffy Model to mark-recapture data of individuals with unknown age collected from 1995 to 2021. We found the growth trajectories to follow the patterns observed in other freshwater turtle species: juveniles exhibited a rapid growth rate and the growth slowed as individuals approached the assumed size of sexual maturity. Estimated growth coefficients were higher for females (k = 0.40) than males (k = 0.22). Female growth slowed significantly after the age of 12 or at a straight-line carapace length (SCL) of 275 mm. Male growth slowed at the age of 20 or at SCL of 312 mm. Although growth rates of C. serpentina have been widely studied, previous research focused mainly on northern populations. We estimated growth rates in a region where turtles are active year round, which aids in understanding the life-history traits of C. serpentina in the southern portion of their distribution.

We tested whether individual females of two species of aquatic turtles, Texas cooters (Pseudemys texana) and red-eared sliders (Trachemys scripta elegans), inhabiting headwaters of the San Marcos River, Hays County, Texas, selectively used the same nesting areas within and among years over a 20-year period. The study area was divided into four quadrants, and chi-square analyses confirmed that for within and among years, females of both species selected quadrants unequally. Our results thus confirm that females of both species at the study site exhibited nest area fidelity within and among years.

We conducted a mark-recapture study on snapping turtles (Chelydra serpentina) at the headwaters of the San Marcos River, Hays County, Texas. The site is within a highly modified urban environment partially surrounded by a golf course, athletic fields, remnants of a theme park, and roadways supporting high traffic volume. We conducted the study from 1996-2011. We captured 179 turtles (89 adult females, 77 adult males, and 13 juveniles). We recaptured males significantly more frequently than females. We estimated population size to be 215 individuals with a density of 26/ha. The annual estimated probability of capture was 0.33, and estimated annual survivorship was 0.94 for males, 0.93 for females, and 0.81 for juveniles.

We studied the morphological characters of the keeled earless lizard, Holbrookia propinqua, in Guadalupe County, Texas, near its type locality (Wilson County, Texas) and at the northern extension of its range. Adults of this population were similar to those of other mainland populations but significantly smaller than adults of coastal island populations. Juveniles of the population in Guadalupe County and a coastal population showed no significant differences in size. Tail length of males did not differ among mainland populations but differed significantly from those of the island populations.

Freshwater turtles are appropriate organisms for studying maternal investment in offspring because, unlike most long-lived vertebrates, turtles show high fecundities and most provide no parental care. We studied reproductive patterns of two emydine freshwater turtle species, the Texas river cooter (Pseudemys texana) and the red-eared slider (Trachemys scripta elegans) at Spring Lake, Hays County, Texas during the 2009 nesting season. Forty-six percent of all nesting Texas river cooters and 25% of all nesting red-eared sliders nested twice, with some Texas river cooters nesting more than twice. Mean egg mass, egg length, and egg width decreased in subsequent clutches in Texas river cooters. However, there was an insufficient sample size of subsequent clutches (n = 6) to draw conclusions for red-eared sliders. Red-eared sliders did not show a positive relationship between clutch size and body size. We found that in both species there was a positive relationship between egg width and egg mass in relation to maternal body size. However, only Texas river cooters showed a positive relationship between clutch size and maternal size, while only red-eared sliders showed a positive relationship between egg length and maternal size. By comparing reproductive parameters of these two coexisting populations, we concluded that the members of these two species allocate resources differently for reproduction.

We studied two closely situated (6.4 km distance) coastal populations of the Gopherus berlandieri in Cameron County, Texas. The Yturria Ranch population was monitored from 1972 through 1987, and the Reed Ranch population was monitored from 1977 through 1987. Tortoises were located by searching between grid lines 18.3 m apart that encompassed 3.3 ha on the Yturria Ranch and 2.0 ha on the Reed Ranch. Nine (3.7%) of 244 tortoises marked on the Yturria Ranch and 16 (10.5%) of 151 marked on the Reed Ranch died during the study. Timing of known deaths were distinctly different for the two sites, with nine tortoises found dead on the Yturria Ranch from 1983-87, whereas all known tortoise deaths occurred on the Reed Ranch from 1977-79. Annual survivorship estimates were higher for males and females on the Yturria Ranch, but survivorships at both sites were similar. Abundance of prickly pear (Opuntia engelmannii), on which tortoises feed, on the Yturria Ranch site may have contributed to a higher survivorship by providing high water content biomass during droughts and by providing cover that reduced predation.

I observed 215 nesting events of Pseudemys texana (134) and Trachemys scripta (81) from 25 April to 14 July 2008 on a golf course in Hays County, Texas. For P. texana, 111 (82.8%) nested one time, 21 (15.7%) nested twice, and 2 (1.5%) nested three times. For T. scripta, 53 (65.4%) nested one time, 24 (29.6%) nested twice, 3 nested three times (3.7%), and 1 nested four times (1.2%). Both species had an internesting interval of ca. 30 days between first and second clutches. Subsequent internesting intervals were shorter but samples were not sufficient to address whether this was fortuitous. On their first attempt, 82% of P. texana and 78% of T. scripta completed nesting. Nesting was diurnal with most activity occurring before noon. Neither distance to nesting site from water nor number of days from the first nesting event to the next nesting event varied with length of plastron. Observé 215 acontecimientos de nidificación de Pseudemys texana (134) y de Trachemys scripta (81) del 25 abril a 14 julio del 2008 en un campo de golf en el condado de Hays, Texas. Ciento once (82.8%) P. texana anidaron sólo una vez, 21 (15.7%) anidaron dos veces, y 2 (1.5%) anidaron tres veces. Cincuenta y tres (65.4%) T. scripta anidaron sólo una vez, 24 (29.6%) anidaron dos veces, 3 anidaron tres veces (3.7%), y 1 anidaron cuatro veces (1.2%). Ambas especies tuvieron un intervalo de tiempo entre nidificación de aproximadamente 30 días entre las primeras y segundas puestas. Los intervalos subsiguientes entre puestas fueron más cortos pero los tamaños de la muestra no fueron suficientes para concluir si esto fue fortuito. El ochenta y dos por ciento de P. texana y 78% del T. scripta terminaron la nidificación en su primer intento. La nidificación fue diurna con la mayoría de las actividades ocurriendo antes del mediodía. Ni la distancia del lugar del nido hasta el agua ni el número de días del primer acontecimiento de nidificación hasta el segundo varió con la longitud del plastrón.

En Texas central, la mocasín boca de algodón (Agkistrodon piscivorus) habita en pequeñas corrientes de baja productividad con lecho de piedra caliza caracterizadas por variabilidad en flujos estacionales. Un estudio de 11 años de la mocasín boca de algodón fue realizado en Honey Creek, una corriente, alimentada por manantiales, que fluye 3.2 km a su confluencia con el río Guadalupe, condado de Comal, para determinar cómo este depredador usó espacio en este sistema estrecho, lineal y dinámico. Durante 57 muestreos a lo largo del área de estudio de 1,564 m, 39 adultos sexualmente maduros, 14 subadultos y 4 juveniles fueron marcados. Las tasas de recaptura no variaron entre los sexos, pero hubo más hembras que machos (2.31) y los adultos fueron recapturados más frecuentemente que los juveniles. Las distancias entre capturas fueron menos que lo pronosticado (si las distribuciones fueran aleatorias), y las distancias no variaron con el número de capturas, ni con el tiempo entre capturas.

Presentamos las primeras estimaciones robustas de supervivencia aparente de la mocasín de boca de algodón (Agkistrodon piscivorus leucostoma) en Texas central. Las estimaciones presentadas fueron obtenidas utilizando el modelo de Cormack-Jolly-Seber que se ajusta por la detectabilidad. La probabilidad anual aparente de supervivencia de la mocasín de boca de algodón localizada en Honey Creek, condado de Comal, Texas, una corriente alimentada por un manantial que fluye 3.2 km a su confluencia con el río Guadalupe, fue 0.81 y fue consistente con estimaciones para especies semejantes de serpientes. A pesar de la probabilidad baja del descubrimiento (0.12) y la muestra relativamente pequeña (n  =  51), la estimación de supervivencia fue razonablemente precisa (coeficiente de variación de 4%). Un beneficio de nuestro estudio es que utilizamos un conjunto de datos a largo plazo (11 años) que abarcó inundaciones y sequías múltiples, y por lo tanto, representa una relativamente gran variedad de condiciones a las que las mocasines de boca de algodón están expuestas en esta localidad.