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| Lace monitor - Varanus varius | |
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| Tweet Topic Started: Jan 8 2012, 11:06 PM (67 Views) | |
| Venomous Dragon | Jan 8 2012, 11:06 PM Post #1 |
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![]() The Lace Monitor is one of Australia's largest monitor species, probably being second in size to the Perentie Varanus giganteus of arid Australia. Specimens over 2 metres are known. Although Brattstrom (1973) reports a maximum total length for a sample of this species at 765cm, larger specimens almost certainly occur. Queensland specimens don't appear to grow as large as those from New South Wales and Victoria. Lace Monitor's are found in most wooded parts of east and south-east Australia including along the Murray/Darling river basins and nearby areas. Large males attain up to about 2 metres in length, while adult females are consistently smaller, rarely attaining 1.5 metres in length. They are distinguished from all other Australian monitors by the following suite of characteristics, (as taken from Reptiles and Amphibians of Australia by H.G. Cogger, (1975). The tail is laterally compressed, except at the base. There is a distinct median double keel dorsally along the posterior half of the tail. The caudal scales are not arranged in regular rings, as ventral caudal scales are larger than the dorsal caudals. The nostrils are directed laterally and the caudal keel is low to moderate. All supraoculars are small and irregularly distributed. A row of enlarged scales forms a ridge on the inner edge of the basal part of the fourth toe. Having said the above, Lace Monitors are usually easily distinguished from other Australian and non-Australian monitors on the basis of their colour pattern/s and/or general appearance. Examples of fairly typical Lace Monitors, including some of the subjects of this article are pictured in my book Australian Reptiles and Frogs, on pages 121-122 and 201. Essentially two colour morphs are known, both being pictured by Hoser (1989). The broad-banded form was thought to be restricted to males as a sex-linked recessive trait, although John Montgomery in 1988 claimed to have seen a female of that colour morph. Further investigation into the causes or origins of these broad-banded specimens is necessary. Broad-banded specimens seem to be most common in particular places, (usually inland areas), and are usually absent from coastal areas. Juveniles tend to be much more brightly coloured and this fades with age. I have seen what appeared to be a very old broad-banded male from Lightning Ridge, NSW whose colour had evidently faded to be an almost uniform grey. It is not rare for 'normal' morph Lace Monitors to appear to be a near uniform grey colour. In the wild this species only lives in timbered habitat and both colour forms are commonly sympatric. In arid areas it tends to be restricted to along rivers and other treed places. It is normally a shy species and will usually take to a tree when disturbed, keeping the tree trunk between itself and it's observer when possible. Bush walkers often become aware of the presence of a Lace Monitor when a group of birds will gather and attack a roaming specimen, commonly as a result of its intrusion to nesting areas. In the nine year period to 1978, I had dog that was adept at finding specimens of this species by following their scent trails and barking when he found them. Invariably I would have to climb the tree with a noose to catch the lizard. This was usually a lot easier said than done. Although a forager of both ground and trees, the species often appears to remain within a given home range. Stebbins and Barwick (1968) found that a wild specimen of this species wandered 3/4 of a mile in a single day (over 1km). They noted that some wild Lace Monitors seem to have a large home range which they 'tour' spending a few days in each section and sheltering in a particular tree hollow each night. Frauca (1966) noted a Lace Monitor occupying the same tree hollow for three years indicating that home ranges or territories may be long standing. Monitors of the Varanus gouldii species group, commonly found in the same areas as Lace Monitors appear to be far more nomadic in habit and as a consequence more commonly seem to enter built up areas. In areas of the North Coast of New South Wales, Lace Monitors commonly forage around rubbish bins in picnic areas for food scraps, such as bones. Some specimens become so bold as to lose a lot of their fear of humans, and can be approached quite closely. Gary Stephenson noted finding specimens in some areas actually hiding in garbage bins containing rubbish. In early April 1998, this author found a large male foraging amongst rubbish in a picnic area at Akuna Bay, in Kurringai Chase National Park, about 20 km north of Sydney city. The lizard had relatively little fear of humans. Around Sydney where both Lace Monitors and the Heath Monitor (herein called Varanus rosenbergi), (formerly known as a form of Varanus gouldii) occur, the Lace Monitor seems to be most common in the Valleys where the trees are largest whereas the Heath Monitor is more common on the scrubby high ridges. The two areas with the largest populations (and highest densities) of Lace Monitors near Sydney seem to be Bobbin Head and nearby areas and to a lesser extent Arcadia. The Lace Monitor is however fairly common throughout it's range and like all Australian monitors does not appear in any way to be endangered or threatened (as per IUCN or similar classifications). Within Australia there appears to be little if any commercial exploitation of this or any other monitor species and few monitors are kept in captivity here. Most Zoos and sizeable fauna parks in eastern Australia tend to have a pit containing Lace Monitors. These specimens are invariably very large and obese males. Preferred body temperatures for active Lace Monitors were found to be between 34 and 36 degrees celsius by Bartholomew and Tucker (1964), Stebbins and Barwick (1968) and Spellerberg (1972). Heatwole (1976) determined the near lethal temperature for this species to be 43.7 degrees celsius. Monitors do not pant when overheated, but will pump the gular area, (Greer, 1989). I cannot recall ever seeing an obviously overheated Lace Monitor, except on a day when the air temperature got to nearly 50 degrees celcius just outside of Warren, NSW. Three specimens were caught on the ground near a watercourse in the heat of the day and were unable to flee when approached. All recovered later that night as the air temperature dropped. Even when basking in relatively cool weather of under 20 degrees celsius (in captivity), large adult Lace Monitors seem to have little difficulty in elevating their body temperature to such an extent that they feel very warm to touch. Pianka (1982) and Brooker and Wombey (1986) have both noted the 'intelligence' of large monitors, including Lace Monitors, with Pianka describing it as 'Mammalian-level intelligence'. In the period 1970-85, I encountered over a hundred wild-caught Lace Monitors and noted a strong bias in favour of male specimens. The apparent surplus in males of this species has also been noted by others, including John Baker and Gary Stephenson, both who have also come into contact with substantial numbers of adult Lace Monitors. The reason for this apparent surplus of males isn't known, although it may be due to more nomadic 'human eye-catching' habits, or there actually being more males in the wild. LONGEVITY Captive specimens usually appear to live indefinitely without showing signs of ageing (to the untrained observer) and obviously live for many years. Anecdotal evidence on wild specimens indicates a similar situation. I would assume (but not backed up by fact at this stage) that some specimens of this species may live up to 40 years of age. I have received a number of anecdotal, (but not documented), reports of specimens in captivity living for 20 or more years. Kim Kennerson of Wentworthville in Sydney and prior to him some others held an adult male in captivity for 15 years and seven months before it apparently escaped from it's outdoor cage and was attacked and killed by dogs. That specimen was adult when caught at Coonamble, NSW and was apparently in good health when killed. Kennerson (1979) cited a case published in 1937 of a specimen of the same species living for 15 years, Flower (1937). Three of the adults held by myself in the period 1975-83 were obtained from a Mr. John Baker of Greenacre, a Sydney suburb. He had kept them in an outdoor pit, 2.4 metres (8 feet) by 3.6 metres (12 feet), since he caught them in 1969 near Bingarra, NSW. The pit had minimal furnishings and the monitors appeared to be in excellent health at all times. The climates of Sydneyand Bingarra seemed sufficiently similar to present no problems in keeping this species in outdoor enclosures. All specimens were mature adults when caught. In 1983 I passed ALL my adult Lace Monitors (7 in all) to a Mr. Ken Sheppherd of the Sydney suburb of St. Clair, where until 1991 all continued to be in good health, whereupon they were released in a wildlife reserve. The three specimens from Bingarra would have to have been at least nearly 30 years of age if not more. None appeared to have shown visible (to me) signs of ageing, although all three keepers (Baker, myself and Sheppherd) avoided overfeeding the lizards. http://www.smuggled.com/lacmon2.htm |
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| Venomous Dragon | Jan 8 2012, 11:07 PM Post #2 |
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My favourite species |
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