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Desert Tortoise Ecology and Precipitation, Mojave and Sonoran Deserts—Data

Desert tortoise (Gopherus agassizii and Gopherus morafkai) reproductive ecology and precipitation data, Arizona and California, 1995-2013


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Lovich, J.E., Ennen, J.R., Averill-Murray, R.C., and Agha, Mickey, 2017, Desert tortoise reproductive ecology and precipitation, Mojave and Sonoran Deserts—Data: U.S. Geological Survey data release,


Estimated precipitation data were compiled using the WestMap web site ( from 1995-2013. We selected pixels on the map shown on their web site that were in the core of our study areas: one near Palm Springs, California and the other at Sugarloaf Mountain in the Tonto National Forest of Arizona. WestMap uses PRISM data to make point measurements of climate data and a digital elevation model of terrain to create estimates of monthly climate elements. Estimates are derived for a 4km grid, for ease in mapping and GIS applications. PRISM is an integrated set of rules, decision making, and calculations designed to imitate the process an expert climatologist would go through when mapping climate data. We were [...]


Point of Contact :
Josh Ennen
Originator :
Joshua R. Ennen, Jeffrey E. Lovich, Roy C. Averill-Murray, Mickey Agha
Metadata Contact :
Terence Arundel
Publisher :
U.S. Geological Survey
Distributor :
U.S. Geological Survey - ScienceBase
USGS Mission Area :
SDC Data Owner :
Southwest Biological Science Center

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USGS_2017_JLovich_Ecology_Evolution_Precipitation_Data.xml 53.25 KB


The purpose of the tortoise data are to compare and contrast the reproductive strategies of the two species relative to their environments and test theories related to reproductive investment related to egg size and clutch size/frequency. The purpose of the precipitation data are to understand the influence of the amount and timing (e.g., winter or summer) of precipitation on egg width and variability. We collected monthly precipitation from two biologically important periods (i.e., winter and summer) for each site. We collected winter precipitation (October-March) because germination of annual plants, which are staples in tortoise diets, in the Mojave and Sonoran Deserts are associated with timing and quantity of winter precipitation. Both timing and amount of winter precipitation are associated with reproductive output in both species. We collected summer precipitation (i.e., June-September) as a variable associated with environmental conditions experienced by eggs and hatchlings.


The authors of these data request that data users contact them regarding intended use and to assist with understanding limitations and interpretation. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

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DOI doi:10.5066/F7JS9NN9

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