Mojave desert tortoise(Gopherus agassizii)thermal ecology and reproductive success along a rainfall cline

Desert resource environments(e.g.microclimates,food)are tied to limited,highly localized rainfall regimes which generate microgeographic variation in the life histories of inhabitants.Typically,enhanced growth rates,reproduction and survivorship are observed in response to increased resource availability in a variety of desert plants and short-lived animals.We examined the thermal ecology and reproduction of US federally threatened Mojave desert tortoises(Gopherus agassizii),long-lived and large-bodied ectotherms,at opposite ends of a 250-m elevation-related rainfall cline within Ivanpah Valley in the eastern Mojave Desert,California,USA.Biophysical operative environments in both the upper-elevation,“Cima,”and the lower-elevation,“Pumphouse,”plots corresponded with daily and seasonal patterns of incident solar radiation.Cima received 22%more rainfall and contained greater perennial vegetative cover,which conferred 5°C-cooler daytime shaded temperatures.In a monitored average rainfall year,Cima tortoises had longer potential activity periods by up to several hours and greater ephemeral forage.Enhanced resource availability in Cima was associated with larger-bodied females producing larger eggs,while still producing the same number of eggs as Pumphouse females.However,reproductive success was lower in Cima because 90%of eggs were depredated versus 11%in Pumphouse,indicating that predatory interactions produced counter-gradient variation in reproductive success across the rainfall cline.Land-use impacts on deserts(e.g.solar energy generation)are increasing rapidly,and conservation strategies designed to protect and recover threatened desert inhabitants,such as desert tortoises,should incorporate these strong ecosystem-level responses to regional resource variation in assessments of habitat for prospective development and mitigation efforts.

Tropical Climates May Be Suitable for Endangered Desert Tortoise Exhibits, Rescues, Adoptions

Governmental, educational, environmental and other nonprofit organizations have placed efforts on conservation action for the threatened Mojave desert tortoise (Gopherus agassizii). While federal and state institutions have focused on the desert tortoise in its native habitat of the southwestern United States, there are other conservation groups whose work has been dedicated to the rescue, rehabilitation, rescue, placement and adoption of the desert tortoise in civilian homes and neighborhoods as well as sanctuaries, reserves and exhibits. AWAKE Community (AWAKE), a nonprofit organization dedicated to natural wildlife habitats and endangered species, has focused its research on desert tortoises in captivity. The California Turtle and Tortoise Club (CTTC), the official adoption arm of California’s Department of Fish and Wildlife (CDFW), has provided instruction on methods of care for desert tortoises raised in captivity including housing, feeding, sexing, health and hibernation for both adults and hatchlings. AWAKE’s research has been aimed at benefiting and supplementing the guidelines provided by CTTC, specifically for coastal climates. AWAKE’s research has also aimed to provide insight to be considered for expanding adoption possibilities to other locations, specifically tropical climates, as adoption needs for desert tortoises have increased. This manuscript presents an analysis of one coastal and one tropical climate that can serve as a basis for: 1) understanding and evaluating climate in both existing and potential habitats for desert tortoise adoptions, rescues and exhibits, 2) providing insight and special instruction for desert tortoise adoptions in coastal communities, and 3) expanding awareness around desert tortoise needs in captivity.