Defending young against intruders is a potentially risky behavior, and is energetically costly. Yet female eastern red-backed salamanders, Plethodon cinereus, guard their clutches for many weeks and aggressively defend eggs against predators and conspecifics. I examined the effect of clutch age, clutch size, and attendant size on the level of aggression attained during nest defense by staging conspecific invasions of nests of brooding female P. cinereus in the laboratory. I predicted that older and larger clutches would elicit increased aggression from the guarding females, and that larger females would be more aggressive when defending. The females were significantly more aggressive when guarding older clutches (6 wk postoviposition) than younger clutches (4 wk postoviposition). However, there was no difference in aggressive behavior when females guarded large (10-egg) or small (4-egg) clutches. There was also no relationship between body size and level of aggression; females were aggressive regardless of their size. These results suggest that females are able to evaluate the age (or developmental stage) of their eggs and adjust expenditure accordingly, but are not differentially responsive to clutch size.

I used skeletochronological data to evaluate the contributions of propagule size, larval/juvenile growth, and age at first reproduction to differences in adult body size in two species of plethodontid salamanders of the genus Desmognathus. The traits in question were evaluated in populations of the larger D. quadramaculatus and smaller D. monticola in the southern Blue Ridge Mountains of North Carolina, USA. Gompertz and von Bertalanffy functions were fitted to the plots of standard length on skeletochronological age of each complete sample (larvae and/or juveniles, and adults) of earlier data sets; linear functions were fitted to data of immatures (larvae and/or juveniles). In order to examine the relationship of body mass and age, I conducted regressions of body mass on standard length in later samples of both species, calculated estimated body masses of the salamanders in the skeletochronological data sets, and then fitted a modified Gompertz function to each plot of body mass on age. The results showed that age at first reproduction is the principal factor contributing to differences between the species in size at first reproduction and adult size. Larger propagule sizes (i.e., hatching sizes) in D. quadramaculatus versus D. monticola may also be a factor; however, there is no evidence that a difference in larval/juvenile growth rate contributes to the adult size differential. Comparison of two populations of D. monticola suggested that small differences in adult body size result mainly from slight differences in age at first reproduction. Tradeoffs among propagule size, clutch size, growth, and age and size at first reproduction are discussed in the context of selective pressures that may have generated diversification in body size and life history in the genus.

Because gopher tortoises (Gopherus polyphemus) occupy high-value lands in the southeastern United States, are declining throughout their range, and stir public passion when they are entombed through currently legal take, refined conservation measures for this species are needed. Of particular interest is a determination of how many individuals constitute a population and what sized areas are required by such populations so that animals currently in harm's way might be moved to designated reserve areas. We use surveys of burrows of gopher tortoises from a large sample of areas of differing sizes to test for a relaxation of the linear relationship between area and number of burrows expected at the edge of a population of gopher tortoises. For measures of burrow abundance, some of our data are from sites on which estimates were based on transect samples; on other sites, complete counts were made. The relationship between area and abundance was elevated for transect samples compared to similar data from complete counts, indicating that transect data yield inflated counts when extrapolated over large areas. For complete counts, our data indicate a threshold point at which a linear relationship between area and abundance ends and a loss of this relationship for larger areas begins. This threshold point suggests that, on average, populations of gopher tortoises consist of 444 burrows, cover 755 ha, and contain 240 tortoises. These figures describe features of tortoises inhabiting a variety of lands that differ in current management goals and past land-use history. Our results suggest that many current reserve areas for gopher tortoises are likely to be too small. Our results also provide an example of how key conservation variables can be generated for long-lived species.

The northern Madagascar spider tortoise (Pyxis arachnoides brygooi), is endemic to the coastal Mikea forests of southwest Madagascar. Very little is known of P. a. brygooi's ecology; however, it is suspected that the range is now very fragmented, with remaining populations facing significant threats from habitat destruction and poaching for food and the pet trade. A line-transect survey was undertaken that systematically surveyed the suspected historical range of this subspecies. The results were incorporated into a GIS database, which revealed that the distribution was confined to 20.5% of the suspected historical range, across three fragmented populations covering 499.6 km². It appears that a zone of intergradation has developed in a transitional area between the southern range of P. a. brygooi and the northern range of P. a. arachnoides. The results of this survey are currently being applied to management plans for newly gazetted protected areas in the region, in an effort to safeguard these relatively small remaining populations.

Escape theory is a well-known conceptual framework proposed to predict adaptive behavior patterns of free-ranging prey animals with respect to predator avoidance. Escape-theory models are based on the premise that prey should adopt behavior that balances predation risk incurred by remaining in a chosen location against the cumulative fitness costs resulting from fleeing such locations. Ectotherms are expected to be more vulnerable when their locomotory abilities are diminished at lower ambient temperatures, and risk to prey is expected to increase with the intensity of threat posed by potential predators. We conducted field experiments involving approach by a simulated predator (a human observer) to test both the influence of substrate temperature and the intensity of threat on escape behavior in free-ranging juvenile collared lizards, Crotaphytus collaris. As predicted by theory, flight initiation distance was negatively correlated with substrate temperature. Our results also supported the prediction that the intensity of juvenile responses should increase with perceived threat intensity. Juveniles fled or hid in more trials when they were approached directly; direct approach resulted in subjects responding when the predator stimulus was farther away, and for trials in which hatchlings fled, they moved farther when approached directly. Taken together, our results indicate that juvenile collared lizards alter their behavior with respect to increased risk in a manner that is consistent with the predictions of contemporary escape theory.

During encounters with predators, prey that flee into refuges decide how long to hide. Refuge use theory predicts that hiding time increases as the risk of emerging increases. Lizards that escape by autotomizing their tails incur costs, including temporary decrease in speed and loss of ability to use autotomy. Thus, risk of being captured upon emergence is greater after autotomy. Also, a predator that captures a prey may later be assessed as posing greater threat. We predicted that hiding time increases after a lizard has been captured or has undergone autotomy. A previous study of striped plateau lizards (Sceloporus virgatus) showed that the proportion of lizards that entered refuges increased after autotomy but not after earlier capture. To examine unstudied effects of autotomy and capture on hiding time, we conducted a 2 × 2 factorial field experiment with handling and autotomy as factors. The four groups were (1) unhandled intact controls; (2) unhandled autotomized; (3) captured (and handled) intact, but not autotomized; and (4) captured, handled and autotomized. Because entering cool refuges entails costly decrease in body temperature, hiding times are shorter in cooler refuges. We controlled this effect statistically by conducting analyses of covariance incorporating difference in air temperature inside and outside refuges as the covariate. As predicted, autotomy and handling led to longer hiding times. However, handling affected hiding time only in intact lizards. Our results add autotomy and capture to risk factors known to affect hiding time, augmenting a growing body of knowledge supporting the hypothesis that trade-offs between costs of emerging and remaining in a refuge guide decisions about hiding time.

We examined the question of whether an apparently restricted diet qualifies the Florida sand skink (Plestiodon reynoldsi) as a dietary specialist. We gathered diet data from the three existing sources, added new data from individuals that we collected, and used these data to calculate measures of dietary diversity. We compared the diet of P. reynoldsi with those of 25 species of skinks, nine species of fossorial squamates, and six species of lizards and snakes found in habitats similar to those occupied by P. reynoldsi. We estimated diet choice indirectly and applied standards of specialization drawn from the literature. In every regard, the Florida sand skink did not seem to have a restricted diet. Dietary diversity values for the species are near the center of the distribution of values for skinks and for the species found in similar habitats. The species has a higher than expected H′ value, based on the identity of its main prey, and the highest or nearly highest dietary diversity values among the fossorial species examined. The diet of the species did not stabilize over the course of four diet studies; rather, the cumulative number of prey types taken nearly doubled. We suggest that the apparently restricted diet of P. reynoldsi reflects the restricted prey choices provided by its foraging sites. A major problem in studying dietary specialization is the lack of data on prey availability and therefore a lack of solid information on diet choice.

We describe the gonadal and fat-body cycles and their relationship to environmental factors for Cuban female Anolis lucius (Polychrotidae). We obtained monthly samples of lizards from the karstic caves at Boca de Jaruco, Havana, Cuba. The lizards reached sexual maturity at 45.0 mm snout–vent length and at approximately 7 mo of age. Female A. lucius showed seasonal reproduction from March to August. The nonreproductive season occurred from September to February, as identified by the absence of active ovogenesis. Vitellogenic ovaries, and almost all females having one or two oviductal eggs, characterized the peak reproductive interval from May to August. In contrast, fat-body mass diminished from May to July and reached its highest values from September to January. The clutch size is one egg per oviposition, and oviposition events occurred from July to September. Increased photoperiod and environmental temperature induced ovarian activity.

Los ciclos gonadal y de los cuerpos grasos, y su relación con factores ambientales son descritos para las hembras del lagarto cubano Anolis lucius (Polychrotidae). Mensualmente algunos lagartos fueron capturados en las cuevas cársicas de Boca de Jaruco, La Habana, Cuba. La madurez sexual fue alcanzada con 45 mm de longitud hocico–cloaca y aproximadamente a los 7 meses. El ciclo reproductivo es estacional y la reproducción ocurrió desde marzo a agosto. La estación no reproductiva identificada por ausencia de actividad gonadal, ocurrió desde septiembre a febrero. La máxima actividad reproductiva fue observada desde mayo a julio, todas las hembras presentaron ovarios vitelogénicos y en su mayoría uno o dos huevos oviducales. En contraste, los cuerpos grasos disminuyeron desde mayo a julio y alcanzaron sus máximos valores desde septiembre a enero. Las puestas son de un huevo por cada vez desde el mes de julio a septiembre. Incrementos del fotoperíodo y de la temperatura ambiental indujeron la actividad ovárica.

One critical life-history trait for organisms is how energy is allocated among the individual offspring they produce. One way of examining the expected trade-off between number of offspring and offspring size is by examining how females respond to different amounts of resources. It has been predicted that females with increased energy uptake should allocate these resources to extra eggs if this does not decrease the size of the other offspring from an optimal value. However, the trade-off of egg size and number is more problematic when considering species that have small clutches (and very large eggs), because changing clutch size requires a large investment per additional egg (the fractional egg size hypothesis). Thus, species with large eggs and small clutches may be more likely to apportion additional energy into increasing offspring size than to increasing clutch size. This prediction has been tested rarely in reptiles. In this study, we placed females of the diadem snake, Spalerosophis diadema (a species that produces very large eggs in small numbers), on either high- or low-energy diets and then recorded reproductive traits after oviposition. As predicted, there was a negative correlation between clutch size and mean egg mass. Females on high-energy diets did not modify clutch size but produced larger eggs relative to those on low-energy diets. However, there was no difference in variance in egg size between diets. Our data therefore support one of the predictions from the fractional egg size hypothesis (larger eggs rather than larger clutch sizes) but not the second prediction that egg size should be more variable in smaller clutches.

One of the most important life-history traits for organisms is age at first reproduction. The benefits of early reproduction often trade off with survival of the female and/or with her growth. Prey availability has been shown to be important in determining strategies for adult trade-offs of reproductive traits in snakes, but its impact on maturity has rarely been studied. We examined the role of energy intake on the brown house snake, Lamprophis fuliginosus, on trade-offs in growth, maturity, and reproductive traits. Six female full-sibling offspring from 10 wild-caught dams were raised on either a high diet (50% of their body mass per week) or a low diet (20% per week) until they mated and laid eggs. Both diet and family influenced growth rates. Forty-eight out of 60 snakes mated, and 37 of these laid eggs within the 20 months. Mean days to first mating was nearly 100 days earlier for animals on the high diet. Within each treatment females did not differ from each other in mating age. The females on the low diet mated at a smaller size than the females on the high diet and laid fewer eggs. However, when adjusted by female snout-to-vent length as a covariate clutch size did not differ between diets. These results suggest there is a minimum size and age below which females will not ovulate. Females with faster growth may bypass that minimum even though earlier reproduction would produce a faster generation time. The trade-off with increased reproductive output in these bigger females may offset the benefits of an earlier maturity and produce equivalent fitness. Finally, we provide evidence that age of maturity may have an additive genetic effect, i.e., may be heritable and thus evolvable based on a significant family effect.

We used radiotelemetry to study the movements and habitat use in a population of Nerodia fasciata fasciata in the upper coastal plain of South Carolina from 2002 to 2006. Snakes that were surgically implanted with radiotransmitters were tracked during late spring of each year and located most days until the onset of hibernation in mid-November. Data were divided into summer and fall for seasonal analysis. Most home-range estimates and associated measures were significantly smaller during fall. Banded watersnakes used shoreline and littoral zone habitats in excess of their availability and used open water and terrestrial habitats relatively infrequently. Shoreline habitats were used more often during the fall, whereas littoral zone habitats were used more in the summer. Movement frequency was high relative to what has been reported for other Nerodia species. Females used shoreline habitats more than males, whereas males used littoral zone habitats more frequently.

Recently four subspecies of Chironius multiventris were recognized as valid distinct species: C. m. foveatus, C. m. multiventris, C. m. cochranae, and C. m. septentrionalis. Although C. foveatus and C. septentrionalis clearly deserve specific status, a re-evaluation of the characters pointed in the literature as diagnostic of C. multiventris and C. cochranae does not support their recognition as valid distinct taxa. Additionally, our analysis of the scutellation pattern, continuous characters, and hemipenial morphology of 34 specimens, and of the available data in literature, shows that there are no significant differences between them. We therefore suggest that C. cochranae should be synonymized with C. multiventris.