Bendami, S. & M. Znari

Estimating food and water intakes by the herbivorous Moroccan Uromastyx nigriventris using a calibrated faecal output method and microhistological analyses. pp. 240-250.

Abstract. The Moroccan Spiny-tailed lizard Uromastyx nigriventris is a desert agamid species distributed from western Algeria to Morocco northeast to southwest of the Atlas range. In spite of a few studies investigating its dietary habits information regarding the daily food intake rate of this non-drinking desert species under natural conditions is lacking. Our study aimed at assessing the daily food consumption in spring and autumn calculated as dry matter intake (DMI), using calibrated faecal and nitrogenous waste outputs collected during 12 days from unfed wild-caught adult lizards originating from a desert area in southeastern Morocco. We used microhistological analyses to identify plant fragments in faecal pellets. Percentages of dry weights of individual plant species in individual diets were estimated from their fragment density, using the Sparks and Macheleck’s conversion method. The obtained results indicate that these herbivorous lizards fed on a total of 18 different plant species belonging to 17 genera and nine plant families depending on the season. The total faecal and nitrogenous waste outputs were significantly correlated to the DMI of captive lizards. The combination of the two methods along with the moisture content of the plant species consumed allowed estimating the lizards’ daily water intake rate (WIR). Estimated values of both DMI and WIR were compared to those predicted from body weight using  allometric (or scaling) equations derived from isotopic measurements of field metabolic rate and water influx in free-ranging herbivorous lizards. The obtained results have important implications for conservation such as captive-breeding programmes and habitat restoration.

Key words. Squamata, Agamidae, Spiny-tailed lizard, faeces calibration, food consumption, water intake, frequency conversion, microhistological faecal analysis.