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Seasonal activity and energetics of two species of varanid lizards in tropical Australia

Christian, Keith A., Corbett, L.K., Green, Brian and Weavers, Brian W. (1995). Seasonal activity and energetics of two species of varanid lizards in tropical Australia. Oecologia,103(3):349-357.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 49 times in Scopus Article | Citations

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Title Seasonal activity and energetics of two species of varanid lizards in tropical Australia
Author Christian, Keith A.
Corbett, L.K.
Green, Brian
Weavers, Brian W.
Journal Name Oecologia
Publication Date 1995
Volume Number 103
Issue Number 3
ISSN 0029-8549   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-0028797438
Start Page 349
End Page 357
Total Pages 9
Place of Publication Germany
Publisher Springer
Field of Research BIOLOGICAL SCIENCES
Abstract The field metabolic rates (FMR) and rates of water flux were measured in two species of varanid lizards over five periods of the year in tropical Australia. The energetics of these species were further investigated by directly measuring activity (locomotion) and body temperatures of free-ranging animals by radiotelemetry, and by measuring standard metabolic rate (over a range of body temperatures) and activity metabolism in the laboratory. Seasonal differences in the activity and energetics were found in these goannas despite similar, high daytime temperatures throughout the year in tropical Australia. Periods of inactivity were associated with the dry times of the year, but the onset of this period of inactivity differed with respect to habitat even within the same species. Varanus gouldii, which inhabit woodlands only, were inactive during the dry and late dry seasons. V. panoptes that live in the woodland had a similar seasonal pattern of activity, but V. panoptes living near the floodplain of the South Alligator River had their highest levels of activity during the dry season when they walked long distances to forage at the receding edge of the floodplain. However, during the late dry season, after the floodplain had dried completely, they too became inactive. For V. gouldii, the rates of energy expenditure were 196 kJ kg−1 day−1 for active animals and 66 kJ kg−1 day−1 for inactive animals. The rates of water influx for these groups were respectively 50.7 and 19.5 ml kg−1 day−1. For V. panoptes, the rates of energy expenditure were 143 kJ kg−1 day−1 for active animals and 56 kJ kg−1 day−1 for inactive animals. The rates of water influx for these two groups were respectively 41.4 and 21.0 ml kg−1 day−1. We divided the daily energy expenditure into the proportion of energy that lizards used when “in burrows”, “out of burrows but inactive”, and “in locomotion” for the two species during the different seasons. The time spent in locomotion by V. panoptes during the dry season is extremely high for a reptile (mean of 3.5 h/day spent walking), and these results provide an ecological correlate to the high aerobic capacity found in laboratory measurements of some species of varanids.
Keywords Ecological energetics
Field metabolic rate
Seasonality
Varanus
Water flux
DOI http://dx.doi.org/10.1007/BF00328624   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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