enhg.4t.com/newsletter/apr2000.htm
Seasonal comparisons for Spiny-tail Lizards (Dhubs)
by Peter Cunningham
"Winter observations of the daily activity pattern, of a population of Spiny-tail lizards (Uromastyx aegyptius microlepis), in the Al Ain region has resulted in the following comparisons: [Summer comparisons are indicated in bold parenthesis]
The lizards emerge later than during the hot summer months, with the earliest emergence recorded at 09h10 (06h55) and the peak between 10h30 and 12h00 (with an average ambient temperature of 22’C (30’C) at emergence). More time above ground is spent basking, with an average of 2 hours 32 minutes (1h40m) spent on this activity. Basking accounts for 23% (14%) of the total available daylight.
Five of the 20 study individuals did not emerge at all to bask and/or forage, something not observed during the summer observations. Time spent foraging was on average 53 minutes (33 minutes) which is 8% (4%) of the available daylight. A peak foraging period occurs between 12h00 and 14h00 (09h00 and 10h00) with lizards returning to their burrows when the ambient temperature is 23’C (40’C). Only 45% of the observed individuals ventured out to forage as opposed to 95% during summer. This can be attributed to the individuals weighing up the cost benefits of energy expenditure during foraging when the available vegetation is scarce and of low quality (higher cellulose & lignin and lower protein values of vegetation).
Lizards spend more time basking, after foraging bouts, compared to the often immediate submergence during summer. The latest submergence of an individual witnessed during winter was at 15h55. Dhubs spent more of the available daylight hours, during winter, above ground (31% VS 13%) and less time submerged 69% (87%).
The furthest distance travelled to forage by an individual was 120 metres (280 m) with the mean distance being 48 metres (60m).
A faecal analysis of 85 fresh pellets was conducted to determine insect utilisation during winter as a source of protein supplement. No insect remains were found although 11% of the pellets analysed contained sheep faeces and 4% date kernels and feathers, respectively. This suggests a more opportunistic foraging behaviour during winter than during summer.
No differentiation was made between the sexes as it is virtually impossible to tell the sexes apart in the field and it would also be expected that the behaviour and diet selection would change after good rains, something not able to be determined during this study.
A total of 480 observation hours (40 dhubs) was conducted (summer & winter) during above mentioned study."
www.wetlands.org/RSDB/_COP9Directory/Directory/1DZ009.html
"Importance: The Iherir Valley contains sites of international importance that provide rare and unique representative examples of an ancient wetland. The isolated nature of the site has led to remarkable evolutionary phenomena described as "both a laboratory and a museum of evolutionary processes." Species which have been most able to adapt to the desertification of the area are the lizards Agama bibroni, A. mutabilis and Uromastyx acanthinurus, and the snakes Cerastes cornutus mutila and Psammophis spp."
"The area is characterised by the presence of endemic vegetation such as Myrtus nivelli and Olea laperrini. The Rocky mountain walls bear rich pictoral evidence of some of the first human inhabitants of the Sahara."
Interesting about the babies.....
ubcouncil.kuniv.edu.kw/kjse/english/wordfile/Volume_31_2004/Volume_1/pdf/effect.pdf Cunningham AND "Uromastyx aegyptius"&hl=en&gl=ca&ct=clnk&cd=9" target="_blank">72.14.203.104/search?q=cache:5ZVrOMnfNhIJ
ubcouncil.kuniv.edu.kw/kjse/english/wordfile/Volume_31_2004/Volume_1/pdf/effect.pdf Cunningham AND "Uromastyx aegyptius"&hl=en&gl=ca&ct=clnk&cd=9
"When the eggs hatch, the mother returns and eats all except three of her young, which she carries on her back until they are able to fend for themselves (Clayton & Wells 1994)."
More...about the vegetation...
www.ctfc.es/symposium/abstracts/Abstract book.htm
"An interesting adaptation is the use of microhabitats provided by burrows of Uromastyx aegyptius; squatting on the surface of the carpet-like foliage of Corchorus depressus; shading in under Acacia tortillus tree and Panicum turgidum grass or standing on top of tall vegetation. During the midday, Lanius excubitor sheltered in the shade of the same trees they use as hunting perch during morning and late afternoons."
Corchorus depressus
www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=250064389
Panicum turgidum grass
www.fao.org/AG/AGP/AGPC/doc/gallery/pictures/newpictures/pantur.htm
www.tortoisetrust.org/articles/uromastyx.html
The Spiny-Tailed Lizard at home - Uromastyx acanthinurus in southern Morocco
A C Highfield & Tahar Slimani
