Artificial water points: Hotspots of extinction or biodiversity?

Copyright © 2009 Elsevier Ltd. All rights reserved.Arian D. Wallach and Adam J. O’neil

Threatened species indicate hot-spots of top-down regulation

© 2009 Museu de Ciències NaturalsThe introduction of alien mesopredators and herbivores has been implicated as the main driver of mammalian extinction in Australia. Recent studies suggest that the devastating effects of invasive species are mitigated by top-order predators. The survival of many threatened species may therefore depend on the presence and ecological functioning of large predators. Australia's top predator, the dingo (Canis lupus dingo), has been intensively persecuted across the continent and it is extremely rare to find dingo populations that are not being subjected to lethal control. We predicted that the presence of threatened species point out places where dingo populations are relatively intact, and that their absence may indicate that dingoes are either rare or socially fractured. A comparison of a site which harbors a threatened marsupial, the kowari (Dasyuroides byrnei), and a neighboring site where the kowari is absent, offers support for this suggested pattern.A. D. Wallach & A. J. O’Neil

Roe deer and decapitated anemone flowers

The roe deer (Capreolus capreolus) has been locally extinct from the East Mediterranean since the beginning of the 20th century. A reintroduction program has been initiated in Israel where several deer have been released in the southern Carmel Mountains. The diet of roe deer is markedly different from that of other local ungulates. Their unique dietary preference for the generally unpalatable geophyte Anemone coronaria is especially notable. They typically consume anemone by "decapitating" the flowers, leaving the rest of the stem intact. We studied the consumption rate of anemone in four hand-reared deer in the Hai Bar Nature Reserve. During the flowering season, each deer consumed 65.5 ± 13.13 and 37.6 ± 13.85 anemone flowers/day in 2003 and 2004, respectively. These results indicate that roe deer may have a profound influence on anemone populations. Being secretive and flighty animals, roe deer are hard to detect. A preliminary survey conducted in Ramat HaNadiv Park, where a roe deer population of an unknown size exists, suggested that with proper calibration, the typical, easy-to-detect decapitated anemone flower might be used for monitoring roe deer presence and density.Arian D. Wallach, Moshe Inbar and Uri Shana

Can threatened species survive where the top predator is absent?

Copyright © 2009 Elsevier B.V. All rights reserved. ScienceDirect® is a registered trademark of Elsevier B.V.Top predators have been described as highly interactive keystone species. Their decline has been linked to secondary extinctions and their increase has been linked to ecological restoration. Several authors have recently argued that the dingo Canis lupus dingo is another example of a top predator that maintains mesopredators and generalist herbivores at low and stable numbers, thereby increasing biodiversity and productivity. Due to the sensitivity of many Australian species to introduced mesopredators and herbivores, the top predator hypothesis predicts that threatened species will not survive where dingoes are rare or absent. However, several threatened species have survived inside the Dingo Barrier Fence (DBF). We present a new view on the survival of the yellow-footed rock-wallaby Petrogale xanthopus xanthopus and the malleefowl Leipoa ocellata inside the DBF where the dingo is considered very rare, or in areas where the dingo is believed to have been eradicated several decades ago. We found that dingoes co-occurred with both threatened species. Dingoes were present at all wallaby colonies surveyed and occurred throughout their range. The most common predator detected in areas inhabited by the wallabies was in fact the dingo, and we found no significant difference between dingo abundance inside compared to outside the DBF. Malleefowl nests were found to be scent marked by dingoes at the three sites that we surveyed, despite these sites being close to human settlement and sheep farms, and in small and fragmented patches of wilderness. These findings provide further evidence for an association between the presence of dingoes and the survival of threatened species, which is in agreement with the top predator hypothesis. The results of this study challenges the current assumption that the presence and ecological consequence of dingoes in sheep country are negligible and we suggest that wildlife managers verify whether dingoes are present before predator control is initiated.Arian D. Wallach, Brad R. Murray and Adam J. O’Neil

Predator control promotes invasive dominated ecological states

Arian D. Wallach, Christopher N. Johnson, Euan G. Ritchie and Adam J. O'Neil