Characteristics of Litters and Juvenile Dispersal in the Endangered Australian Skink Tiliqua adelaidensis

Milne, Tim; Bull, C. Michael; Hutchinson, Mark N.

doi:10.2307/1565812

Cited by 13 publications

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“…It also coincides with the time when lizards are most frequently trapped in pitfalls, and most frequently taken by predators (Milne 1999). Despite these movements, and the dispersal movements of juvenile lizards (Milne et al 2002), burrows appear to be an essential resource for lizards for a range of activities.…”

Section: Discussionmentioning

confidence: 84%

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Use of burrows by the endangered pygmy blue-tongue lizard, Tiliqua adelaidensis (Scincidae)

Milne¹,

Bull²,

Hutchinson³

2003

Wildl. Res.

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The pygmy blue-tongue lizard, Tiliqua adelaidensis, had been considered extinct until its recent rediscovery near Burra in the mid-north of South Australia. The lizards apparently rely on spider burrows with a single entrance as refuge sites. In this paper we describe observations from all-day video recordings of the entrances of burrows occupied by lizards on 31 days across the spring and early summer of 1996. The lizards spent most of each day either retreated down the burrow or basking at the burrow entrance. Early in the season, when temperatures were cooler, lizards spent more of each day basking, and more of their basking time fully emerged from the burrow, than later in the season. Results are consistent with the hypothesis that the lizards thermoregulate by moving in and out of the burrow. Lizards also fed by making short excursions from the burrow, often to catch passing invertebrate prey, although they also fed on flowers early in spring. Later in the season lizards were more likely to vacate their burrows for longer times, or to move away from their burrows, and mating activity was observed when males approached burrows occupied by females. The observations suggest that pygmy blue-tongue lizards rely heavily on burrows for many activities, and that any conservation management scheme for this endangered species will rely on maintaining an adequate supply of burrows. W R 0 2 0 8 7 B u r r o w u s e i n p y g m y bl u e -t o n g u e l i z a r d s T . Mi l n e e t a l .

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Section: Discussionmentioning

confidence: 84%

“…This was the site where the species was rediscovered in 1992 (Armstrong et al 1993), and has been described previously (Milne et al 2002). The area has hot, dry summers and cool, moist winters, and an average annual rainfall of 446 mm.…”

Section: Methodsmentioning

confidence: 93%

Use of burrows by the endangered pygmy blue-tongue lizard, Tiliqua adelaidensis (Scincidae)

Milne¹,

Bull²,

Hutchinson³

2003

Wildl. Res.

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“…Tiliqua adelaidensis is a long-lived (up to 9 years) skink that gives birth to 2-4 live young in late summer (Milne et al 2002). For over 30 years T. adelaidensis was considered extinct; however, since its rediscovery in 1992 (Armstrong et al 1993) it has been found inhabiting remnant patches of degraded native grassland in the mid-northern agricultural region of South Australia (Hutchinson et al 1994;Fig.…”

Section: Introductionmentioning

confidence: 99%

Restricted gene flow in the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) in a fragmented agricultural landscape

et al. 2009

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Habitat fragmentation can have several adverse genetic impacts on populations. Assessing the extent of these threatening processes is essential in conservation management. In the present study, we investigated the genetic population structure of the endangered pygmy bluetongue lizard, Tiliqua adelaidensis, which is now restricted to a few small fragments of its previously more extensive grassland habitat. The aim of our study was to investigate genetic diversity and gene flow both among and within sample sites. The information will assist in making recommendations for habitat conservation and translocation programs. We collected DNA from 229 individuals from six isolated sample sites and genotyped them for 16 polymorphic microsatellite loci. Across all six sample sites, observed heterozygosity ranged from 0.75 to 0.82. There was no evidence of population bottlenecks and little evidence of inbreeding due to consanguineous mating. Genetic differentiation was low to moderate although significant for all pairs of sample sites (F ST = 0.021-0.091). Results from Bayesian clustering analyses revealed distinct clusters in the overall sample and suggested restricted gene flow between sample sites separated by distances ranging from 1.7 to 71.6 km. By using spatial autocorrelation, we also found a significant genetic structure within sample sites at distances up to 30 m, suggesting restricted gene flow even in small patches of continuous habitat. It will be important to preserve this finely clustered population structure in captive breeding and translocation programs. Increasing opportunities for gene flow through habitat corridors or population augmentation may help maintain genetic diversity and prevent an increase in differentiation. Although endangered species do not always present model systems for studying fragmentation, our approach shows how important genetic information can be acquired to aid conservation in highly fragmented ecosystems.

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“…Pygmy bluetongue lizards rarely make social contacts with conspecifics, except during mating when males seek out females (Milne et al 2003;Fenner and Bull 2009), and following parturition when live-born neonates may remain in the mother's burrow for several weeks before dispersing (Milne et al 2002). In the current study we have shown that these lizards may use scats located close to their burrows as social signals.…”

Section: Indirect Social Interactionsmentioning

confidence: 99%

“…Lizards prefer the deepest burrows available, and optimal refuges are often in short supply (Souter 2003;Fellows et al 2009). Mating takes place in late October and early November (Fenner and Bull 2009;Milne et al 2002), and one to four live young are born in late January to early March (Milne et al 2002). Lizards move infrequently from their burrow refuges, usually for periods less than 20 min, and rarely have direct encounters with neighbouring conspecifics outside of the mating season (Fellows 2008;Milne et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Responses of the endangered pygmy bluetongue lizard to conspecific scats

Fenner

Bull

2010

J Ethol

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Many animals use chemical signals for communication between conspecifics and for territory marking. The pygmy bluetongue lizard is normally solitary, focussing activity around the entrance of its burrow, from where it ambushes prey, and rarely contacts other individuals. In this paper we examined whether lizards in laboratory experiments alter their behaviour in the presence of scats from conspecifics. In the first experiment, when lizards were offered a choice of two vacant burrows with or without a scat close to the entrance, they tongue flicked more often at the burrow entrance when the scat was present, and more often chose to occupy the burrow with the scat. An interpretation is that lizards use scat signals to recognise burrows that may be suitable because they have previously been occupied by a conspecific, but that they approach those burrows cautiously in case a resident is still present and likely to resist a takeover. Scats from male lizards were inspected (by both sexes) for longer than scats of female lizards. In the second experiment, when resident lizards were presented with scats outside of their burrows, they inspected and tongue flicked at those scats more often if the scat came from a male than a female lizard, but there was no definitive evidence from our experiments that lizards differentiated in their response to scats from lizards that were found close to or far from the test lizard. The results were consistent with a communication system in which lizards use scats to advertise their presence, independent of any direct contact.

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Characteristics of Litters and Juvenile Dispersal in the Endangered Australian Skink Tiliqua adelaidensis

Cited by 13 publications

References 0 publications

Use of burrows by the endangered pygmy blue-tongue lizard, Tiliqua adelaidensis (Scincidae)

Use of burrows by the endangered pygmy blue-tongue lizard, Tiliqua adelaidensis (Scincidae)

Restricted gene flow in the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) in a fragmented agricultural landscape

Responses of the endangered pygmy bluetongue lizard to conspecific scats

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