Activity and Burrow Structure of Attwater's Pocket Gopher (Geomys attwateri)

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Abstract
Activity of Attwater's pocket gopher (Geomys attwateri) was monitored by radio-telemetry and related to burrow structure and temperature at the Welder Wildlife Refuge, Texas. In May 1984, radio fixes were taken hourly over a 2-day period on 10 individuals and each position was marked aboveground. After completion of radiotracking, entire burrow systems were excavated and mapped. Architecture of burrow systems did not reflect local variation in total above-ground biomass. Average area covered by the burrow systems was 202 m2, mean total length of burrows in a system was 91 m, and mean minimum distance moved between fixes was 4.3 m with no difference between sexes. Distance moved was less in more convoluted burrow systems and was correlated positively with length of burrow systems. Body mass was not correlated with burrow length or distance between fixes. More than 60% of the fixes were localized in the vicinity of a nest or refuge and neither sex exhibited a diel activity period. There was little daily variation in temperature in the burrow because of insulation by the soil. We conclude that architecture of burrow systems was not adaptive to resource availability, and that burrow size and configuration affected underground movement, but not frequency of activity. The looping burrow structure of G. attwateri contrasts with the linear, branched systems reported for other geomyids and may be an adaptation to low primary production or social interactions in southern Texas.