Individual and population energetics of a lizard on a Mediterranean islet

Richard P. Brown*, V. Pérez-Mellado, J. Diego-Rasilla, J. A. Garcia, A. Naranjo, J. R. Speakman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Population density in the lacertid lizard Podarcis lilfordi on the Mediterranean islet of Nitge, Menorca, Balearic Islands, was found to be 12 190 ind · ha -1 (SE, ±2135), exceeding densities reported for other island or mainland lizard populations. Field metabolic rates in P. lilfordi were measured by the doubly labeled water method, allowing estimation of a population metabolizable energy demand of 13.86 MJ · ha -1 · day -1 -only 9.8% of that for a theoretical mammal population of the same body mass and density. Energy demand was considerably higher than that estimated for other lizard populations, primarily due to high population density but also because of high individual daily energy expenditure (1255 KJ · day -1 ; body mass=5.13 g). Field metabolic rates were partitioned into maintenance and activity components by respirometry of captive animals at field body temperatures. Activity metabolism formed the main component (77.4%) of total respiratory metabolism resulting from a combination of long daily activity periods (ca. 12 h), and greatly elevated metabolism during activity (5.7 times greater than resting levels). It is hypothesized that low food availability per individual constrains the time-energy budget of this species, obligating long periods of intense foraging.

Original languageEnglish
Pages (from-to)500-504
Number of pages5
Issue number4
Publication statusPublished - 31 Oct 1992


  • Balearic islands
  • Energy expenditure
  • Islet
  • Lizard
  • Population density


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