These data were compiled to evaluate the reproductive ecology of Agassiz's desert tortoises (Gopherus agassizzi) in the Sonoran Desert of California using two populations within Joshua Tree National Park, including five reproductive seasons that spanned 20 years (1997-1999, 2015-2016). Compared to their conspecifics inhabiting the Mojave Desert, the reproductive ecology of G. agassizii in the Sonoran Desert is understudied. Climatic variation between the two deserts can affect reproductive ecology, including fecundity and clutch phenology. Mature female tortoises (straight-line carapace length ≥ 20 cm) outfitted with radiotransmitters were located and X-radiographed approximately every 10-14 days during the reproductive season (April-July). The appearance of shelled eggs on X-radiographs allowed for the determination of clutch phenology (dates of appearance and disappearance of shelled clutches), as well as clutch size, clutch number, and X-ray egg width (XREW). XREW was measured at the widest portion of each egg, from the outermost point of each side of the shell, using dial calipers for film and K-PACS software for digital X-radiographs. XREW was determined from the first X-radiograph in which a clutch of eggs was clearly detectable. Data were also compiled on temperature and cumulative precipitation by wet and dry seasons using WestMap (https://cefa.dri.edu/Westmap/), and these data were used to reflect how temperature and precipitation potentially affect reproductive ecology. As a federally listed species, it is important to understand geographic variation in desert tortoise ecology for effective management of the species.

These data were acquired from 7 study sites distributed across the range of Gopherus agassizii. Data were collected from 1997 to 2002 as part of three separate studies, although data were not collected at all sites in each year. Radio-transmitters were attached to the carapace of 151 females and VHF radio-telemetry was used to relocate animals to assess reproductive status. Egg production was determined from X-radiographs taken weekly/biweekly intervals (depending on the study) using a portable X-ray machine between April and July or August of each year. In addition, the mean carapace length (MCL) of each tortoise was measured at each time of capture or recapture using calipers (mm). A nesting event was recorded if a female previously observed with eggs was observed without eggs during a subsequent X-ray session.

These data were acquired from 7 study sites distributed across the range of Gopherus agassizii. Data were collected from 1997 to 2002 as part of three separate studies, although data were not collected at all sites in each year. Radio-transmitters were attached to the carapace of 151 females and VHF radio-telemetry was used to relocate animals to assess reproductive status. Egg production was determined from X-radiographs taken weekly/biweekly intervals (depending on the study) using a portable X-ray machine between April and July or August of each year. In addition, the mean carapace length (MCL) of each tortoise was measured at each time of capture or recapture using calipers (mm). A nesting event was recorded if a female previously observed with eggs was observed without eggs during a subsequent X-ray session.

During a long-term study at the Desert Tortoise Research Natural Area in the western Mojave Desert of California, factors affecting the decline of desert tortoises were evaluated inside the protective fence vs. outside. During the five-survey years, 1,645 sightings of 13 species of avian predators were collected. Eleven species occurred both inside and outside the fenced Desert Tortoise Research Natural Area, and two species, the short-eared owl and great horned owl, occurred only inside the fence. The most abundant predator was the common raven with more observations outside the fence than inside the fence in most years. Ravens are hyper-predators of the desert tortoise and, at the Desert Tortoise Research Natural Area, are one of four drivers of population decline. This species also inhibits recovery because of the high numbers (Berry et al. 2020, Wildlife Monographs 205:1-53). References: Berry, K.H., Yee, J.L., Shields, T.A. and Stockton, L., 2020. The Catastrophic Decline of Tortoises at a Fenced Natural Area. Wildlife Monographs, 205(1), pp.1-53.

This dataset provides spatial predictions of clustering and the genotype association index for the Mojave genotype in local species-environment relationships of Desert Tortoises (Gopherus agassizi and Gopherus morafkaii) for individuals in the subregion encompassing the genetic sampling locations used by Edwards et al. (2015). This region offered an opportunity to explore habitat selection across the ecotone between the Mojave and Sonoran deserts and the secondary contact zone between G. agassizii and G. morafkai, and is referred to as the focal study area. The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to identify multivariate clusters and map them back to geographic space. Inman et al. 2019. Local niche differences predict genotype associations in sister taxa of desert tortoise. Diversity and Distributions. https://doi.org/10.1111/ddi.12927

This dataset provides spatial predictions of clustering and the genotype association index for the Mojave genotype in local species-environment relationships of Desert Tortoises (Gopherus agassizi and Gopherus morafkaii) for individuals in the subregion encompassing the genetic sampling locations used by Edwards et al. (2015). This region offered an opportunity to explore habitat selection across the ecotone between the Mojave and Sonoran deserts and the secondary contact zone between G. agassizii and G. morafkai, and is referred to as the focal study area. The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to identify multivariate clusters and map them back to geographic space. Inman et al. 2019. Local niche differences predict genotype associations in sister taxa of desert tortoise. Diversity and Distributions. https://doi.org/10.1111/ddi.12927

We developed a model for analyzing multi-year demographic data for long-lived animals and used data from a population of Agassiz’s desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area in the western Mojave Desert of California, USA, as a case study. The study area was 7.77 square kilometers and included two locations: inside and outside the fenced boundary. The wildlife-permeable, protective fence was designed to prevent entry from vehicle users and sheep grazing. We collected mark-recapture data from 1,123 tortoises during 7 annual surveys consisting of two censuses each over a 34-year period. We used a Bayesian modeling framework to develop a multistate Jolly-Seber model because of its ability to handle unobserved (latent) states and modified this model to incorporate the additional data from non-survey years. For this model we incorporated 3 size-age states (juvenile, immature, adult), sex (female, male), two location states (inside and outside the fenced boundary) and 3 survival states (not-yet-entered, entered/alive, and dead/removed). We calculated population densities and estimated probabilities of growth of the tortoises from one size-age state to a larger size-age state, survival after 1 year and 5 years, and detection. Our results show a declining population with low estimates for survival after 1 year and 5 years. The probability for tortoises to move from outside to inside the boundary fence was greater than for tortoises to move from inside the fence to outside. The probability for detecting tortoises differed by size-age state and was lowest for the smallest tortoises and highest for the adult tortoises. The framework for the model can be used to analyze other animal populations where vital rates are expected to vary depending on multiple individual states. The model was incorporated into the manuscript that included several other databases for publication in Wildlife Monographs in 2020 by Berry et al.

We developed a model for analyzing multi-year demographic data for long-lived animals and used data from a population of Agassiz’s desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area in the western Mojave Desert of California, USA, as a case study. The study area was 7.77 square kilometers and included two locations: inside and outside the fenced boundary. The wildlife-permeable, protective fence was designed to prevent entry from vehicle users and sheep grazing. We collected mark-recapture data from 1,123 tortoises during 7 annual surveys consisting of two censuses each over a 34-year period. We used a Bayesian modeling framework to develop a multistate Jolly-Seber model because of its ability to handle unobserved (latent) states and modified this model to incorporate the additional data from non-survey years. For this model we incorporated 3 size-age states (juvenile, immature, adult), sex (female, male), two location states (inside and outside the fenced boundary) and 3 survival states (not-yet-entered, entered/alive, and dead/removed). We calculated population densities and estimated probabilities of growth of the tortoises from one size-age state to a larger size-age state, survival after 1 year and 5 years, and detection. Our results show a declining population with low estimates for survival after 1 year and 5 years. The probability for tortoises to move from outside to inside the boundary fence was greater than for tortoises to move from inside the fence to outside. The probability for detecting tortoises differed by size-age state and was lowest for the smallest tortoises and highest for the adult tortoises. The framework for the model can be used to analyze other animal populations where vital rates are expected to vary depending on multiple individual states. The model was incorporated into the manuscript that included several other databases for publication in Wildlife Monographs in 2020 by Berry et al.

These data include environmental covariates used to develop species distribution models for Gopherus agassizii and Gopherus morafkai, along with PCA-reduced environmental covariates used to explore local species-environment relationships within a subregion of the ectone between the two species. We also provide the genotype association used to test the mapped clusters of multiscale geographically weighted regression coefficients against models of (i) a geographically-based taxonomic designation these two sister species, and (ii) an environmental ecoregion designation. These data support the following publication: Inman et al. 2019. Local niche differences predict genotype associations in sister taxa of desert tortoise. Diversity and Distributions. https://doi.org/10.1111/ddi.12927

These data include environmental covariates used to develop species distribution models for Gopherus agassizii and Gopherus morafkai, along with PCA-reduced environmental covariates used to explore local species-environment relationships within a subregion of the ectone between the two species. We also provide the genotype association used to test the mapped clusters of multiscale geographically weighted regression coefficients against models of (i) a geographically-based taxonomic designation these two sister species, and (ii) an environmental ecoregion designation. These data support the following publication: Inman et al. 2019. Local niche differences predict genotype associations in sister taxa of desert tortoise. Diversity and Distributions. https://doi.org/10.1111/ddi.12927