Does sheep grazing affect burrow choice of the pygmy bluetongue lizard ( Tiliqua adelaidensis )?

Nielsen, Torben P.; Fildes, Stephen; Bull, C. Michael

doi:10.1016/j.jaridenv.2017.03.001

Cited by 2 publications

(4 citation statements)

References 39 publications

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“…Vegetation cover indexes derived from satellite images of the field site shows the effect of the grazing regimes, by showing that ungrazed paddocks had more vegetation cover than paddocks grazed by 2.7 sheep/hectare/day in year 1 and paddocks grazed by 2.7 sheep/hectare/day had less vegetation cover than paddocks grazed by 1.5 sheep/hectare/day in year 2 (Nielsen et al . ). Both the paddocks grazed by 2.7 sheep/hectare/day in year 1 and paddocks grazed by 1.5 sheep/hectare/day in year 2 did, however, have vegetation cover index values that were higher than the values of ungrazed paddocks in year 1 and lower than the values of the most intensively grazed paddocks (2.7 sheep/hectare/day) in year 2 (Nielsen et al .…”

Section: Methodssupporting

confidence: 61%

“…The results from the December surveys of year 2 confirm that lizards in paddocks grazed by 1.5 sheep/hectare/day had higher relative body mass than in the paddocks with the more intense grazing treatment, but, contrary to the hypothesis, lizards in ungrazed paddocks in year 1 had a higher relative body mass than lizards in paddocks grazed by 2.7 sheep/hectare/day even though this stocking level resulted in a moderate vegetation density (Nielsen et al . ). Among our grazing treatments, these results indicate that grassland without grazing is the best habitat for the lizards.…”

Section: Discussionmentioning

confidence: 99%

“…Due to variations in vegetation growth and climate, sheep numbers were adjusted between years, based on local farming advice, to allow comparable reductions in vegetation cover (Nielsen et al . ). In year 1 (October 2013–March 2014), three paddocks were ungrazed, while an average of 2.7 ± 0.11SE sheep/hectare/day grazed the remaining three paddocks.…”

Section: Methodsmentioning

confidence: 97%

“…Both the paddocks grazed by 2.7 sheep/hectare/day in year 1 and paddocks grazed by 1.5 sheep/hectare/day in year 2 did, however, have vegetation cover index values that were higher than the values of ungrazed paddocks in year 1 and lower than the values of the most intensively grazed paddocks (2.7 sheep/hectare/day) in year 2 (Nielsen et al . ). This trend was further supported by Clayton and Bull () who compared vegetation dry weight in the paddocks in year 1 and found less vegetation in the grazed paddocks.…”

Section: Methodsmentioning

confidence: 99%

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Effects of grazing regime on the relative body mass of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

Nielsen

Bull

2019

Austral Ecology

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Many animals rely on fat reserves, to keep them alive through extended periods of food shortage, such as the winter, and to provide additional energy for reproduction. Fat reserves, measured relative to an animal's size, are often referred to as the animal's body condition. The present study investigated how different levels of grazing by domestic stock in native grassland habitat affect the body condition of the pygmy bluetongue lizard (Tiliqua adelaidensis), and if these effects are related to changes in the abundance and size of grasshoppers which are the lizards primary source of food. The initial hypothesis was that lizards would have the highest body condition in moderately grazed paddocks, because those paddocks would have more grasshoppers than heavily grazed paddocks, and better visual conditions for lizards to catch those grasshoppers than in ungrazed paddocks. The results, however, showed that both lizard body condition and the abundance of grasshoppers increased with decreasing grazing intensity. The connection between lizard body condition and abundance of grasshoppers was complex. Within an activity season, lizard body condition generally declined from spring to summer, while the number of grasshoppers grew. The mean size of grasshoppers seemed to be more important, as lizard body condition was higher in spring, the time of year with the largest grasshoppers. These results show that the intensity of grazing by domestic stock influences the body condition of pygmy bluetongue lizards, but that this effect is not entirely due to the reduction in the number of grasshoppers resulting from grazing.

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Section: Methodssupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of grazing regime on the relative body mass of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

Nielsen

Bull

2019

Austral Ecology

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The impact of sheep grazing on the fecundity and timing of reproduction in the endangered pygmy bluetongue lizard, Tiliqua adelaidensis

Nielsen

Bull

2017

Amphib Reptilia

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The endangered pygmy bluetongue lizard (Tiliqua adelaidensis) is found only in a few remaining patches of South Australian native grassland, most of which are used for live stock grazing. The lizards occupy spider burrows, they mate in October-November and females produce litters of one to four live born neonates in mid-January-mid-March. In this study we use ultrasound scans of females and observations of neonates in their maternal burrows to investigate how grazing affects the fecundity of the pygmy bluetongue lizard. We predicted that lizards in moderately grazed paddocks would have a higher reproductive output than lizards in hard grazed paddocks. Ultrasound scans indicated that this hypothesis was correct by showing a higher mean number of yolk sacs in females from moderately than from hard grazed paddocks. Females from moderately grazed paddocks also gave birth significantly earlier than females in hard grazed paddocks. The higher number of yolk sacs did not result in a significantly higher number of neonates observed in the burrows, which indicates that the weekly burrow observations used in this study may underestimate true fecundity. Understanding how grazing affects the fecundity of the pygmy bluetongue lizard is essential to the future management of this endangered species. This is not only because grazing is used to manage the habitat of all currently known lizard populations, but also because successful reproduction will be needed in those populations to supply the “surplus” individuals predicted to be essential for relocation programs to ensure the survival of the species.

show abstract

Does sheep grazing affect burrow choice of the pygmy bluetongue lizard ( Tiliqua adelaidensis )?

Cited by 2 publications

References 39 publications

Effects of grazing regime on the relative body mass of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

Effects of grazing regime on the relative body mass of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

The impact of sheep grazing on the fecundity and timing of reproduction in the endangered pygmy bluetongue lizard, Tiliqua adelaidensis

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