Land use and dingo baiting are correlated with the density of kangaroos in rangeland systems

Rangelands worldwide have been subject to broadscale modification,such as widespread predator control,intro-duction of permanent livestock water and altered vegetation to improve grazing.In Australia,these landscape changes have resulted in kangaroos(i.e.large macropods)populations increasing over the past 200 years.Kan-garoos are a key contributor to total grazing pressure and in conjunction with livestock and feral herbivores have been linked to land degradation.We used 22 years of aerial survey data to investigate whether the density of 3 macropod species in the southern rangelands of Western Australia was associated with:(i)land use,including type of livestock,total livestock,density of feral goats,type of land tenure,and kangaroo commercial harvest effort;(ii)predator management,including permitted dingo control effort,estimated dingo abundance,and presence of the State Barrier Fence(a dingo exclusion fence);and(iii)environmental variables:ruggedness,rainfall,fractional cover,and total standing dry matter.Red kangaroos(Osphranter rufus)were most abundant inflat,open vegetation,on pastoral land,where area permitted for dingo control was high,and numbers were positively associated with antecedent rainfall with a 12-month delay.Western grey kangaroos(Macropus fuliginosus)were most abundant onflat,agricultural land,but less abundant in areas with high permitted dingo control.Euros(Osphranter robustus)were most abundant in rugged pastoral land with open vegetation,where permitted dingo control was high.While environmental variables are key drivers of landscape productivity and kangaroo populations,anthropogenic factors such as land use and permitted dingo control are strongly associated with kangaroo abundance.

Keeping an ear out:size relationship of the tympanic bullae and pinnae in bandicoots and bilbies(Marsupialia:Peramelemorphia)

Bandicoots and bilbies(Order Peramelemorphia)occupy a broad range of habitats across Australia and New Guinea,from open,arid deserts to dense forests.This once diverse group has been particularly vulnerable to habitat loss and introduced eutherian predators,and numerous species extinctions and range retractions have occurred.Understanding reasons for this loss requires greater understanding of their biology.Morphology of the pinnae and tympanic bullae varies markedly among species.As hearing is important for both predator avoidance and prey location,the variability in ear morphology could reflect specialization and adaptation to specific environments,and therefore be of conservation relevance.We measured 798 museum specimens representing 29 species of Peramelemorphia.Controlling for phylogenetic relatedness and head length,pinna surface area was weakly negatively correlated with average precipitation(rainfall being our surrogate measure of vegetation productivity/complexity),and there were no environmental correlates with effective diameter(pinna width).Controlling for phylogenetic relatedness and skull length,tympanic bulla volume was negatively correlated with precipitation.Species that inhabited drier habitats,which would be open and allow sound to carry further with less obstruction,had relatively larger pinnae and tympanic bullae.In contrast,species from higher rainfall habitats,where sounds would be attenuated and diffused by dense vegetation,had the smallest pinnae and bullae,suggesting that low-frequency hearing is not as important in these habitats.Associations with temperature did not reach statistical significance.These findings highlight linkages between hearing traits and habitat that can inform conservation and management strategies for threatened species.