Near-global impact of the Madden-Julian Oscillation on rainfall

The accuracy of synoptic-based weather forecasting deteriorates rapidly after five days and is not routinely available beyond 10 days. Conversely, climate forecasts are generally not feasible for periods of less than 3 months, resulting in a weather-climate gap. The tropical atmospheric phenomenon known as the Madden-Julian Oscillation (MJO) has a return interval of 30 to 80 days that might partly fill this gap. Our near-global analysis demonstrates that the MJO is a significant phenomenon that can influence daily rainfall patterns, even at higher latitudes, via teleconnections with broadscale mean sea level pressure (MSLP) patterns. These weather states provide a mechanistic basis for an MJO-based forecasting capacity that bridges the weather-climate divide. Knowledge of these tropical and extra-tropical MJO-associated weather states can significantly improve the tactical management of climate-sensitive systems such as agriculture.

Increased reproductive success in older female red kangaroos and the impact of harvesting

Wildlife harvesting has a long history in Australia, including obvious examples of overexploitation. Not surprisingly, there is scepticism that commercial harvesting can be undertaken sustainably. Kangaroo harvesting has been challenged regularly at Administrative Appeals Tribunals and elsewhere over the past three decades. Initially, the concern from conservation groups was sustainability of the harvest. This has been addressed through regular, direct monitoring that now spans > 30 years and a conservative harvest regime with a low risk of overharvest in the face of uncertainty. Opposition to the harvest now continues from animal rights groups whose concerns have shifted from overall harvest sustainability to side effects such as animal welfare, and changes to community structure, genetic composition and population age structure. Many of these concerns are speculative and difficult to address, requiring expensive data. One concern is that older females are the more successful breeders and teach their daughters optimal habitat and diet selection. The lack of older animals in a harvested population may reduce the fitness of the remaining individuals; implying population viability would also be compromised. This argument can be countered by the persistence of populations under harvesting without any obvious impairment to reproduction. Nevertheless, an interesting question is how age influences reproductive output. In this study, data collected from a number of red kangaroo populations across eastern Australia indicate that the breeding success of older females is up to 7-20% higher than that of younger females. This effect is smaller than that of body condition and the environment, which can increase breeding success by up to 30% and 60% respectively. Average age of mature females in a population may be reduced from 9 to 6 years old, resulting in a potential reduction in breeding success of 3-4%. This appears to be offset in harvested populations by improved condition of females from a reduction in kangaroo density. There is an important recommendation for management. The best insurance policy against overharvest and unwanted side effects is not research, which could be never-ending. Rather, it is a harvest strategy that includes safeguards against uncertainty such as harvest reserves, conservative quotas and regular monitoring. Research is still important in fine tuning that strategy and is most usefully incorporated as adaptive management where it can address the key questions on how populations respond to harvesting.