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Our knowledge of the conservation status of reptiles, the most diverse class of terrestrial vertebrates, has improved dramatically over the past decade, but still lags behind that of the other tetrapod groups. Here, we conduct the first comprehensive evaluation (~92% of the world's ~1714 described species) of the conservation 1 Joint senior authors. D.G. Chapple et al.

Various proximate mechanisms have been proposed to explain sexual size dimorphism (SSD) in vertebrates. Identifying the proximate causation of SSD allows insight into the ultimate reasons why SSD exists. I explored whether differential growth rates and (or) mortality explain SSD in the lizard Elgaria coerulea (Baird and Girard, 1852). I estimated growth parameters for males and females using the logistic-by-weight growth curves and determined survivorship using two complimentary methods: standard life-table calculations and capture–recapture methods. The former calculated age-specific survivorship, whereas the latter tested for differences in survivorship between males and females while considering differences in their recapture rates. I considered age-specific SSD as further evidence of SSD independent of differential mortality. Differences in growth asymptote, not intrinsic growth rate, contribute to SSD in this population. SSD is not due to differential mortality, as there is no difference in survivorship of males and females over 3 years of age. In addition, there is age-specific SSD with females larger than males for individuals 4 years of age and greater. The female-biased SSD may be a result of selection for large body size, although further studies are necessary to identify the ultimate cause of SSD in this species.

Northern regions limit ectotherms to relatively short periods of feeding and breeding interrupted by long periods of inactivity. This may force cool-climate ectotherms into different ecological or demographic trade-offs than their southern conspecifics. Our aim is to examine demography, morphology, reproduction, habitat use, and hibernation by populations of Red-bellied Snake (Storeria occipitomaculata) near their northern range limit. This research was conducted in southwestern Manitoba and data on summer activity were collected from April to September 2007–2009 using coverboard and pedestrian surveys. Hibernation sites were monitored over three winters (2007–2008, 2008–2009, and 2009–2010), and thermal profiles of Formica ant mounds were collected in 2008–2009 and 2009–2010. Females reached sexual maturity at a smaller size than most other populations that have been reported but appear to have similar clutch sizes to the rest of the range. The majority of adult females captured at our summer sites were gravid (96%) suggesting annual reproduction, and activity patterns suggest fall breeding. Near its northern range maxima, this species appears to use relatively warm habitat, have rapid reproduction, and co-opt ant mounds to survive in a difficult climatic environment. Much remains unknown and future studies should further examine the variation in size at maturity and the relationship between body size and clutch size. In addition, little is known about diet, benefits of fall mating, use of open prairie habitats, and late-season migration by S. occipitomaculata.

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