A triple threat: high population density,high foraging intensity and flexible habitat preferences explain high impact of feral cats on prey

Alien mammalian carnivores have contributed disproportionately to global loss of biodiversity. In Australia, predation by the feral cat and red fox is one of the most significant causes of the decline of native vertebrates. To discover why cats have greater impacts on prey than native predators, we compared the ecology of the feral cat to a marsupial counterpart, the spotted-tailed quoll. Individual prey are 20–200 times more likely to encounter feral cats, because of the combined effects of cats'' higher population densities, greater intensity of home-range use and broader habitat preferences. These characteristics also mean that the costs to the prey of adopting anti-predator behaviours against feral cats are likely to be much higher than adopting such behaviours in response to spotted-tailed quolls, due to the reliability and ubiquity of feral cat cues. These results help explain the devastating impacts of cats on wildlife in Australia and other parts of the world.     

The roles of statistical inference and historical sources in understanding landscape change: the case of feral buffalo in the freshwater floodplains of Kakadu National Park

The statistical analysis of Bowman et al. ( Journal of Biogeography , 2008, 35 , 1976–1988) revealed the weak relationship between the rate of woody cover encroachment onto the freshwater floodplains in the central section of Kakadu National Park (KNP) over a 40-year period and estimates of proximate water buffalo ( Bubalus bubalis ) density. The analysis relied on detailed mapping of buffalo tracks, the best historical record of spatial variation of buffalo density in KNP. In their reply, Petty & Werner ( Journal of Biogeography , 2009, doi: [DOI link] ) prefer to privilege an amalgam of historical sources to claim that buffalo removal is the primary driver of the woody expansion on floodplains. The contrasting weight placed on data analysis and differences of interpretation underscore a tension between statistically based historical ecology approaches and environmental history narratives, a tension that forms part of the broader cultural clash between the Sciences and Humanities.     

Recolonizing carnivores: Is cougar predation behaviorally mediated by bears?

Conservation and management efforts have resulted in population increases and range expansions for some apex predators, potentially changing trophic cascades and foraging behavior. Changes in sympatric carnivore and dominant scavenger populations provide opportunities to assess how carnivores affect one another. Cougars (Puma concolor) were the apex predator in the Great Basin of Nevada, USA, for over 80 years. Black bears (Ursus americanus) have recently recolonized the area and are known to heavily scavenge on cougar kills. To evaluate the impacts of sympatric, recolonizing bears on cougar foraging behavior in the Great Basin, we investigated kill sites of 31 cougars between 2009 and 2017 across a range of bear densities. We modeled the variation in feeding bout duration (number of nights spent feeding on a prey item) and the proportion of primary prey, mule deer (Odocoileus hemionus), in cougar diets using mixed‐effects models. We found that feeding bout duration was driven primarily by the size of the prey item being consumed, local bear density, and the presence of dependent kittens. The proportion of mule deer in cougar diet across all study areas declined over time, was lower for male cougars, increased with the presence of dependent kittens, and increased with higher bear densities. In sites with feral horses (Equus ferus), a novel large prey, cougar consumption of feral horses increased over time. Our results suggest that higher bear densities over time may reduce cougar feeding bout durations and influence the prey selection trade‐off for cougars when alternative, but more dangerous, large prey are available. Shifts in foraging behavior in multicarnivore systems can have cascading effects on prey selection. This study highlights the importance of measuring the impacts of sympatric apex predators and dominant scavengers on a shared resource base, providing a foundation for monitoring dynamic multipredator/scavenger systems.     

Potential vectors of West Nile virus following an equine disease outbreak in Italy

In the late summer of 1998, an outbreak of equine encephalomyelitis due to West Nile virus (WNV) occurred in the Tuscany region of central Italy. The disease was detected in 14 race horses from nine localities in four Provinces: Firenze, Lucca, Pisa and Pistoia. The outbreak area included Fucecchio wetlands (1800 ha), the largest inland marsh in Italy, and the adjacent hilly Cerbaie woodlands with farms breeding horses. To detect potential vectors of WNV, entomological surveys of Fucecchio and Cerbaie were undertaken during 1999-2002 by collecting mosquito larvae from breeding sites and adult mosquitoes by several methods of sampling. Among 6023 mosquitoes (Diptera: Culicidae) collected, 11 species were identified: Aedes albopictus (Skuse), Ae. vexans (Meigen), Anopheles atroparvus Van Thiel, An. maculipennis Meigen s.s., An. plumbeus Stephens, Culex impudicus Ficalbi, Cx. pipiens L., Culiseta longiareolata Macquart), Ochlerotatus caspius (Pallas), Oc. detritus (Haliday) and Oc. geniculatus (Olivier). In Fucecchio marshes, Cx. impudicus predominated with seasonal peak densities in spring and autumn: its greatest abundance during early spring coincides with arrival of migratory birds from Africa. In Cerbaie hills, Cx. pipiens predominated with peak population density in late summer. No viruses were isolated from 665 mosquitoes processed. These findings, plus other data on Italian mosquito bionomics, suggest a possible mode of WNV transmission involving the most abundant Culex in the Fucecchio-Cerbaie areas. Culex impudicus, being partly ornithophilic, might transmit WNV from migratory to non-migratory birds during springtime; Cx. pipiens, having a broader host range, would be more likely to transmit WNV from birds to horses and, perhaps, to humans by late summer.     

Successful restoration of Metrosideros polymorpha (ʻōhiʻa) is possible in forest sites with active Rapid ‘Ōhiʻa Death infections

Rapid ?ōhi?a Death (ROD), caused by the fungal pathogen Ceratocystis, is killing large numbers of ?ōhi?a trees (Metrosideros polymorpha) in Hawai?i. ?ōhi?a are a dominant tree in Hawaiian forests, have a range that goes from arid to wet forest climates, and are important for endangered species habitat and ecosystem function. To test whether actively planting ?ōhi?a seedlings is a viable restoration strategy in areas with high ROD mortality, we planted ?ōhi?a in a ROD‐affected forest and crossed this with weeding and fencing treatments to compare ROD mortality to other stressors. We also tested for viable Ceratocystis spores in soils around planting areas. We found that seedlings were more likely to die in unweeded and unfenced treatments than controls. Although viable Ceratocystis spores were found in soil, none of the 41 dead seedlings tested positive for Ceratocystis. This indicates that competition from exotic plants and exotic feral ungulate damage are more likely to kill seedlings than ROD within the first year after planting.     

Impacts of feral horses in the Australian Alps and evidence‐based solutions

New evidence of impacts by feral horses in Australia's alpine parks systems confirms they endanger threatened species and extensively damage critically endangered bog communities that could take millennia to recover. These impacts are not confounded by effects of deer and accumulate over time, even when only a small number of feral horses (~100) are present. With protected areas representing only a small proportion of the area of the Australian states of New South Wales (9.3%) and Victoria (17%), allowing feral horses to degrade reserves is not a reasonable management compromise, is contrary to the purpose of the protected area system and conflicts with international obligations. Modelling and decades of management experience indicate that trapping alone does not control feral horse numbers. Trapping and fertility control can work in small populations, but not when there are several thousand horses in remote areas. Aerial culling is needed to cost‐effectively and humanely control feral horse populations. The relatively small amount of suffering feral horses experience during a cull is outweighed by (i) avoiding suffering and death of horses from starvation and thirst, (ii) avoiding the suffering of native animals displaced by horses and (iii) avoiding the ethical concerns of driving threatened species towards extinction. Objections to aerial culling on welfare and cultural grounds are contradicted by evidence. Improving knowledge in the general community about what is at stake is long overdue because without this knowledge, small groups with vested interests and unfounded claims have been able to dominate debate and dictate management actions. As a result of ineffective management, horse populations are now expanding and causing well‐documented damage to Australia's alpine parks, placing at risk almost $10M spent on restoration after livestock grazing ended. The costs of horse control and restoration escalate the longer large horse populations remain in the alpine parks. It is crucial that feral horse numbers are rapidly reduced to levels where ecosystems begin to recover. Aerial culling is needed as part of the toolbox to achieve that reduction.     

Camels Out of Place and Time: The Dromedary (Camelus dromedarius) in Australia

The deserts of the Australian outback are ideal territories for dromedary camels, Camelus dromedarius. Dromedaries' flexible adaptations allow them to eat 80% of Australian plant species and they obtain much of their water through ingesting vegetation; they thrive where other species perish. In many ways, the dromedary could be said to “belong” in this harsh environment. Yet for numerous Australians, particularly ranchers, conservation managers, and increasingly local and national governments, camels are perceived as pests and unwelcome invaders. Anthropologists studying human classifications of non-human animals have suggested that those species or populations that fail to fit neatly into existing classification systems come to be considered “out of place,” particularly when they enter human domains or disturb existing perceptual boundaries of environmental order. Through exploring and analyzing academic, government, and media publications, this review proposes that today's Australian dromedaries exemplify “animals out of place” and discusses how and why they have developed this status. It is further suggested that in addition to being classified as “out of place” in Australia, the dromedary has also become “out of time,” as its classification has transformed with temporal shifts in human circumstances, cultural values, and worldviews.     

Retreating Melaleuca swamp forests in Kakadu National Park: Evidence of synergistic effects of climate change and past feral buffalo impacts

Melaleuca swamp forests form a fringe around seasonally inundated freshwater flood plains of Kakadu National Park (KNP). Previous studies based on the analysis of aerial photography reported an increase in woody plant cover on these flood plains, apparently associated with changed fire regimes, increased rainfall and possibly increased atmospheric CO₂. In opposition to this woody vegetation encroachment past high densities of feral buffalo in the 1960 to mid 1980s changed the hydrology of the KNP flood plains, allowing increased penetration of saltwater causing extensive death of Melaleuca forests. Climate change has increased sea levels and there is concern that this will threaten the freshwater ecosystems of KNP. We hypothesized that Melaleuca forests that were previously impacted by high densities of feral buffalo have continued to decline because of salinization driven by sea level rise. We examined this hypothesis by overlaying georeferenced aerial photography taken in 1964, 1984 and 2004 in a geographic information environment, and then constructing generalized linear fixed effects and mixed effects models to rank the statistical strength of different drivers of Melaleuca forest contraction. We found that there has been a 5% overall contraction of Melaleuca forests over the last 50 years on our study sites, although the amount of contraction varied both geographically and temporally. The amount of Melaleuca forest contraction was greatest during the 1984–2004 interval, when buffalo densities were low. Contraction was greatest on the Melaleuca forest edges, at low‐lying sites, and where high densities of buffalo were apparent in 1964. These results suggest the enduring legacy effect of past buffalo damage will amplify the effects of sea level rise on the flood plains of KNP.     

The wild goats Capra aegagrus Erxleben, 1777 of the Mediterranean Sea and the Eastern Atlantic Ocean islands

• 1 Populations of wild goats that can be referred to as phenotypes of the pasang, or Bezoar goat, or wild goat Capra aegagrus Erxleben, 1777, still occur on several of the Mediterranean and Eastern Atlantic islands. Other populations became extinct not many decades ago.
• 2 Fossil evidence for the natural spread of the wild goat to any of these islands has not been found. Originating in the Near East, the region of its natural range and its earliest domestication, the species was introduced by humans onto the Mediterranean islands starting as early as the Pre‐Pottery Neolithic.
• 3 The islands of the Eastern Atlantic were colonized artificially by animals of ‘pre‐Hispanic’ origin. The principal phenotypes expressed by all these populations of goats can be matched with the characteristics of both C. a. aegagrus Erxleben, 1777 (aegagrus phenotype) and C. a. dorcas Reichenow, 1888 (dorcas phenotype).
• 4 Most of these animals currently survive on the islands without being fed by humans, and should be protected.