Population Dynamics of Red Kangaroos (Macropus rufus) in Relation to Rainfall in the South Australian Pastoral Zone

Cairns, S. C.; Grigg, G. C.

doi:10.2307/2404185

Cited by 55 publications

(72 citation statements)

References 32 publications

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“…1). This pattern is consistent with that observed in natural populations (Caughley et al 1984, Bayliss 1985, Cairns and Grigg 1993. Harvesting reduces simulated kangaroo abundance, and kangaroo numbers fluctuate around a lower mean value.…”

Section: Resultssupporting

confidence: 88%

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses to Selective Harvesting?

Tenhumberg

Tyre

Pople

et al. 2004

Ecology

124

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Abstract. There is a wealth of literature documenting a directional change of body size in heavily harvested populations. Most of this work concentrates on aquatic systems, but terrestrial populations are equally at risk. This paper explores the capacity of harvest refuges to counteract potential effects of size-selective harvesting on the allele frequency of populations. We constructed a stochastic, individual-based model parameterized with data on red kangaroos. Because we do not know which part of individual growth would change in the course of natural selection, we explored the effects of two alternative models of individual growth in which alleles affect either the growth rate or the maximum size. The model results show that size-selective harvesting can result in significantly smaller kangaroos for a given age when the entire population is subject to harvesting. In contrast, in scenarios that include dispersal from harvest refuges, the initial allele frequency remains virtually unchanged.

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Section: Resultssupporting

confidence: 88%

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses to Selective Harvesting?

Tenhumberg

Tyre

Pople

et al. 2004

Ecology

124

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“…The trends for both species in each area were similar and mirrored the trends in the entire pastoral zone for that period (Pople et al 1991;Cairns and Grigg 1993). The decline in red kangaroo numbers in 1991 in Area A was certainly far greater than that recorded in the broader region, which showed a more gradual decline to the level in 1992.…”

Section: Resultssupporting

confidence: 58%

“…Within the sheep rangelands of Australia, where dingoes (Canis lupus dingo) are either absent or rare, red kangaroos (Macropus rufus) are food limited (Bayliss 1987;Cairns and Grigg 1993). Density dependence (operating as a feedback loop between kangaroos and pasture) appears weak (Caughley 1987).…”

Section: Introductionmentioning

confidence: 99%

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Trends in the numbers of red kangaroos and emus on either side of the South Australian dingo fence: evidence for predator regulation?

Pople¹,

Grigg²,

Cairns³

et al. 2000

Wildl. Res.

Self Cite

142

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Most of Australia’s sheep rangelands are enclosed by a dingo-proof fence. Within these rangelands, where dingoes (Canis lupus dingo) are rare, red kangaroos (Macropus rufus) are considered to be food limited because their numbers respond to fluctuations in pasture biomass that are driven by highly variable rainfall. Outside this region, where dingoes are common, kangaroo densities are generally substantially lower, suggesting that dingoes are an important limiting factor. However, it is unclear whether dingoes can regulate kangaroo populations. In this study, red kangaroo and emu (Dromaius novaehollandiae) numbers were monitored for varying periods during 1978–92 by aerial survey on both sides of the dingo fence in three areas in the north of the South Australian pastoral zone. Densities of red kangaroos and emus were lower outside the fence, although the disparity varied between areas and over time. The similarity in the environments on both sides of the fence and the marked step in kangaroo density at the fence are consistent with dingoes strongly limiting these prey populations. In the north-east of the pastoral zone, where kangaroo and emu densities are greatest, the contrast in density across the fence was most pronounced. Furthermore, the trends in density over time differed across the fence. Outside the fence, red kangaroos and emus remained at low densities following drought as dingo numbers increased. Inside the fence, red kangaroo and emu populations showed a ‘typical’ post-drought recovery. The data therefore suggest that, in some situations, dingoes may not simply limit red kangaroo and emu populations, but also regulate them. For this to occur, predation rate would need to be density dependent at low prey densities. The availability of alternative prey, and the reduction in the numbers of all prey during drought may provide the mechanism.

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“…In arid and semi-arid Australia, rainfall is the most notable environmental factor affecting kangaroo populations (Newsome et al, 1967;Bayliss, 1985a;Bayliss, 1985b;Robertson, 1986;Shepherd, 1987;Caughley et al, 1985;Cairns and Grigg, 1993;Dawson, 1995;McCullough and McCullough, 2000). Rainfall has a strong influence on cohort survivorship and population age-structure (Robertson, 1986).…”

Section: Introductionmentioning

confidence: 99%

Forage fibre digestion, rates of feed passage and gut fill in juvenile and adult red kangaroosMacropus rufusDesmarest: why body size matters

Munn

Dawson

2006

Journal of Experimental Biology

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SUMMARY Using red kangaroos Macropus rufus Desmarest, a large (>20 kg)marsupial herbivore, we compared the digestive capabilities of juveniles with those of mature, non-lactating females on high-quality forage (chopped lucerne Medicago sativa hay) of 43±1% neutral-detergent fibre (NDF)and poorer quality, high-fibre forage (chopped oaten Avena sativahay) of 64±1% NDF. On chopped lucerne apparent dry matter (DM)digestibilities by young-at-foot (YAF) red kangaroos (an age that would normally be taking some milk from their mother), weaned juveniles and mature females were similar (55–59%). On chopped oaten hay apparent DM digestibility was lower in the YAF (35.9±2.3%) followed by weaned(43.4±2.8%) and mature females (44.6±1%). The digestion of NDF and its components (mainly cellulose and hemicellulose) was lowest among the YAF followed by weaned and then mature females. The YAF and weaned kangaroos could not sustain growth on the poor-quality diet, and appeared to be at or near maximal gut fill on both forages; the values being 114–122 g DM for YAF and 151–159 g DM for weaned kangaroos. Mean retention times (MRT) of particle and solute markers were significantly longer for the YAF and weaned kangaroos on oaten hay than on lucerne hay, and DM intake (g d–1) was ∼50% lower on the oaten hay. In contrast, solute and particle MRTs in the mature females were not significantly affected by diet; they maintained DM intakes by increasing DM gut fill from 264±24 g on chopped lucerne to 427±26 g DM on chopped oaten hay. Clearly, the mature female kangaroos did not maximise gut fill on the high-quality forage,presumably as a consequence of their proportionally lower energy requirements compared with still-growing juveniles. Overall, we have provided the first mechanistic link between the physiological constraints faced by juvenile red kangaroos in relation to their drought-related mortalities, rainfall and forage quality.

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Population Dynamics of Red Kangaroos (Macropus rufus) in Relation to Rainfall in the South Australian Pastoral Zone

Cited by 55 publications

References 32 publications

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses to Selective Harvesting?

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses to Selective Harvesting?

Trends in the numbers of red kangaroos and emus on either side of the South Australian dingo fence: evidence for predator regulation?

Forage fibre digestion, rates of feed passage and gut fill in juvenile and adult red kangaroosMacropus rufusDesmarest: why body size matters

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