Jonathan Kennedy Webb

Jonathan Kennedy Webb
University of Technology Sydney | UTS · School of Life Sciences

BSc (Hons), PhD

About

147
Publications
44,479
Reads
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6,684
Citations
Additional affiliations
May 2001 - May 2012
The University of Sydney
Position
  • PostDoc Position
Description
  • Intraguild predation in snakes; chemical communication in snakes; cane toad impacts on frogs, lizards, snakes and mammals; using conditioned taste aversion to reduce toad impacts on northern quolls.

Publications

Publications (147)
Article
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In many lizards, a mother’s choice of nest site can influence the thermal and hydric regimes experienced by developing embryos, which in turn can influence key traits putatively linked to fitness, such as body size, learning ability, and locomotor performance. Future increases in nest temperatures predicted under climate warming could potentially i...
Article
The 2019–2020 Australian megafires were unprecedented in their intensity and extent. These wildfires may have caused high mortality of adult broad-headed snakes Hoplocephalus bungaroides which shelter inside tree hollows during summer. We evaluated the impacts of two high-intensity wildfires (2002 Touga Fire and 2020 Morton Fire) on a broad-headed...
Article
In many oviparous reptiles, thermal conditions inside nests influence phenotypic traits of hatchlings that are linked to survival. Maternal nest-site selection can therefore have long-term implications for offspring and maternal fitness. We studied nest-site selection in a nocturnal lizard (Amalosia lesueurii) from south eastern Australia. Females...
Article
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The arrival of novel predators can trigger trophic cascades driven by shifts in prey numbers. Predators also elicit behavioral change in prey populations, via phenotypic plasticity and/or rapid evolution, and such changes may also contribute to trophic cascades. Here, we document rapid demographic and behavioral changes in populations of a prey spe...
Article
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In urban bushland, the installation of nest boxes is widely used to compensate for the loss of natural tree hollows. However, current nest box designs may not provide thermal refuges for wildlife during summer heatwaves, particularly if internal temperatures exceed the upper critical temperatures of wildlife. We investigated whether the addition of...
Article
The loss of hollow-bearing trees is a key threat for many hollow-dependent taxa. Nesting boxes have been widely used to offset tree hollow loss, but they have high rates of attrition, and, often, low rates of usage by target species. To counter these problems, chainsaw carved hollows (artificial cavities cut into trees) have become a popular altern...
Article
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Stressful environments in utero can have a profound influence on cognitive functions and learning ability. In lizards, thermal environments experienced by embryos can shape a range of traits, including sex, body size, and locomotor performance, which may influence fitness. Recent studies suggest that incubation temperatures may also influence brain...
Article
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With recent and predicted increases in the frequency and intensity of wildfires, there is a pressing need for mitigation strategies to reduce the impacts of wildfires on human lives, infrastructure and biodiversity. One strategy involves the use of low-flammability plants to build green firebreaks at the wildland–urban interface. It is common, howe...
Article
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Invasive vertebrates are frequently reported to have catastrophic effects on the populations of species which they directly impact. It follows then, that if invaders exert strong suppressive effects on some species then other species will indirectly benefit due to ecological release from interactions with directly impacted species. However, evidenc...
Article
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Heatwaves are a regular occurrence in Australia, and are predicted to increase in intensity and duration in the future. These changes may elevate temperatures inside lizard nests, shortening the incubation period, so that hatchlings are more likely to emerge during heatwaves. Potentially, developmental plasticity or heat hardening could buffer hatc...
Article
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Animals use irruptive movement to avoid exposure to stochastic and pervasive environmental stressors that impact fitness. Beneficial irruptive movements transfer individuals from high stress areas (conferring low fitness) to alternate localities that may improve survival or reproduction. However, being stochastic, environmental stressors can limit...
Article
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The invasion of a toxic prey type can differentially affect closely related predator species. In Australia, the invasive Cane Toad (Rhinella marina) kills native anurophagous predators that cannot tolerate the toad’s toxins; but predators that are physiologically resistant (i.e., belong to lineages that entered Australia recently from Asia, where t...
Article
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Understanding the impacts that invasive vertebrates have on terrestrial ecosystems extends primarily to invaders’ impacts on species with which they interact directly through mechanisms such as predation, competition and habitat modification. In addition to direct effects, invaders can also initiate ecological cascades via indirect population level...
Article
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In many regions, the frequency and duration of summer heatwaves is predicted to increase in future. Hotter summers could result in higher temperatures inside lizard nests, potentially exposing embryos to thermally stressful conditions during development. Potentially, developmentally plastic shifts in thermal tolerance could allow lizards to adapt t...
Article
Invasive species are a leading cause of animal extinctions. It is difficult to eradicate established and widespread populations of invaders, so we need novel approaches to reduce their impact on imperilled wildlife. In Australia, the toxic cane toad Rhinella marina has caused local extinctions of northern quolls Dasyurus hallucatus. Quolls lack imm...
Article
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Despite compelling evidence for substantial individual differences in cognitive performance, it is unclear whether cognitive ability influences fitness of wild animals. In many animals, environmental stressors experienced in utero can produce substantial variation in the cognitive abilities of offspring. In reptiles, incubation temperatures experie...
Article
Many animals use chemical cues to detect conspecifics and predators. On sandstone outcrops, flat rock spiders Morebilus plagusius and Polyrachis ants use sun-exposed rocks as nest sites, and defend rocks from intruders. We investigated whether chemical cues influenced retreat-site selection by spiders. In the field, spiders showed significant avoid...
Article
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Conditioned Taste Aversion (CTA) is an adaptive learning mechanism whereby a consumer associates the taste of a certain food with symptoms caused by a toxic substance, and thereafter avoids eating that type of food. Recently, wildlife researchers have employed CTA to discourage native fauna from ingesting toxic cane toads (Rhinella marina Linnaeus,...
Article
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Communal nesting lizards may be vulnerable to climate warming, particularly if air temperatures regulate nest temperatures. In southeastern Australia, velvet geckos Oedura lesueurii lay eggs communally inside rock crevices. We investigated whether increases in air temperatures could elevate nest temperatures, and if so, how this could influence hat...
Article
Estimating population size is crucial for managing populations of threatened species. In the Top End of northern Australia, populations of northern quolls (Dasyurus hallucatus), already affected by livestock grazing, inappropriate burning regimes and predation, have collapsed following the spread of the toxic cane toad (Rhinella marina). Cane toads...
Article
Prey can enhance their survival by eliciting an appropriate response to predators. Theoretically, prey should distinguish odors of predators and nonpredators. The manifestation of defensive antipredator behaviors has been extensively researched in domestic species (i.e., the relationship between laboratory-bred rats and domestic cats). However, lit...
Article
Fire is a key ecological process influencing the population dynamics of small mammals. Whilst shifting competitive advantage amongst small mammal species following a single fire event is well-documented, there has been little investigation of the potential influence of fire frequency on small mammal interspecific interactions. In this study, we inv...
Article
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Territorial behaviour, whereby dominant animals gain priority access to critical resources, is widespread in some animal lineages, but rare in others. Theory suggests that territoriality will evolve only when animals can economically defend sites that contain critical resources (typically mates, sometimes food). In striking contrast to their close...
Article
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Depredation of nests by native and introduced predators is contributing to the decline of beach-nesting shorebirds in many parts of Australia. Determining the relative importance of these predators is crucial for designing and implementing appropriate management strategies for shorebird conservation. We deployed and monitored 82 artificial Red-capp...
Article
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Introduction: Recent studies at sites in northern Australia have reported severe and rapid decline of several native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic group...
Article
1. Biological invasions often occur through expansion of satellite populations that become established at 'invasion hubs'. Invasion hubs can result from random dispersal events, but fre-quently arise when invading individuals actively choose habitats using cues that signify high-quality environments where the fitness consequences are positive. Theo...
Article
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Introduction: Recent studies at sites in northern Australia have reported severe and rapid decline of several native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic group...
Article
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Many predators are also scavengers that feed on carrion and human refuse. Therefore, the availability of carrion can elevate the abundance or activity of facultative scavengers, amplifying predation pressure on prey. On Australian beaches, fishermen often discard fish carcasses that could attract facultative scavengers, both native, such as Austral...
Article
The spread of invasive species after their initial introduction is often facilitated by human actions. In some cases, invaders only become established in habitats where dominant native species have been displaced as a result of human actions or where humans inadvertently provide essential resources such as food, water or shelter. We investigated if...
Article
Detection and avoidance of predator cues can be costly, so it is important for prey to balance the benefits of gaining food against the costs of avoiding predators. Balancing these factors becomes more complicated when prey are threatened by more than one type of predator. Hence, the ability to recognize species-specific predator odours and priorit...
Data
1. The spread of invasive species after their initial introduction is often facilitated by human actions. In some cases, invaders only become established in habitats where dominant native species have been displaced as a result of human actions or where humans inadvertently pro-vide essential resources such as food, water or shelter. 2. We investig...
Article
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The success of an invasive species can be reduced by biotic resistance from the native fauna. For example, an invader that is eaten by native predators is less likely to thrive than one that is invulnerable. The ability of invasive cane toads (Rhinella marina) to spread through Australia has been attributed to the toad’s potent defensive chemicals...
Article
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Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad (Rhinella marina) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April-October). We investigated whet...
Chapter
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Australia has a spectacular and diverse reptile fauna approaching 1000 species, 93% of which are endemic to the continent. Despite this, there is a paucity of information on the biology of Australian reptiles compared with mammals and birds. The single greatest threat to Australian reptiles is the removal of native vegetation, most of which has occ...
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Continued range expansion into physiologically challenging environments requires invasive species to maintain adaptive phenotypic performance. The adrenocortical stress response, governed in part by glucocorticoid hormones, influences physiological and behavioural responses of vertebrates to environmental stressors. However, any adaptive role of th...
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It is virtually impossible to eradicate invasive organisms once they have spread widely, and even low densities of invaders may have devastating impacts. We need to explore alternative management options that accept the inevitability of encounters between alien and native taxa, but reduce the negative consequences of those encounters. Conditioned t...
Article
Snakes have traditionally been viewed as solitary, asocial animals whose habitat use is driven by temperature, prey and predators. However, recent studies suggest that snake spatial ecology may also be socially mediated. We examined the influence of conspecific chemical cues on refuge selection in a small nocturnal snake (the small-eyed snake) that...
Article
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A detailed understanding of how extensively animals move through the landscape, and the habitat features upon which they rely, can identify conservation priorities and thus inform management planning. For many endangered species, information on habitat use either is sparse, or is based upon studies from a small part of the species' range. The broad...
Article
Worldwide, efforts to restore habitat quality are rarely matched by efforts to evaluate the effects of those restoration attempts. Simply documenting usage of the newly created habitats by biota is not enough, because such areas may serve as sink populations. We need to monitor viability (growth, survival, reproduction) of individuals that colonize...
Article
Fire‐induced changes in canopy openness may affect sunlight penetration to the forest floor, and thus the operative temperatures available to terrestrial ectotherms. We examined thermal regimes for two types of ectotherms: diurnally active species that utilize sun‐exposed patches to regulate their body temperatures, and nocturnally active species t...
Article
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The ecological impact of an invasive species can depend on the behavioural responses of native fauna to the invader. For example, the greatest risk posed by invasive cane toads (Rhinella marina Bufonidae) in tropical Australia is lethal poisoning of predators that attempt to eat a toad; and thus, a predator's response to a toad determines its vulne...
Article
Australia's biogeographical isolation has rendered many endemic species vulnerable to invaders. The recent spread of the cane toad (Rhinella marina) has caused serious population declines for some predatory reptile and mammal species. To determine a priori whether or not cane toad poisoning endangers native species, we can test the fates of predato...
Article
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Abstract In many animal species, males direct more intense courtship towards females they have not previously encountered, than towards females with which they have previously mated. To test the factors responsible for this "Coolidge Effect", we need studies on a wide range of taxa – including those with mating systems in which we would not expect...
Article
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Organisms selecting retreat sites may evaluate not only the quality of the specific shelter, but also the proximity of that site to resources in the surrounding area. Distinguishing between habitat selection at these two spatial scales is complicated by co-variation among microhabitat factors (i.e., the attributes of individual retreat sites often...
Article
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Background To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii) are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides), which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velve...
Data
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Pairwise ΦST values between populations and p-values.
Data
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Maximum parsimony (MP) consensus tree (50% majority rule).
Article
1. In oviparous species providing maternal care, the choice of nest site is crucial for the survival of both the eggs and the mother. Most embryos only develop successfully within a narrow range of incubation conditions, which may differ from the mother's own requirements. 2. How, then, do nest-attending mothers select sites that provide suitable c...
Article
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Context: Invasive species are a leading cause of extinctions, yet predicting their ecological impacts poses a formidable challenge for conservation biologists. When native predators are naïve to invaders, they may lack appropriate behaviours to deal with the invader. In northern Australia, the invasion of the highly toxic cane toad (Rhinella marina...
Article
The ecological impact of an invasive species can be heterogeneous through space and time. One such case in Australia involves native freshwater crocodiles Croco-dylus johnstoni, which are highly sensitive to invasive cane toads Rhinella marina in some areas, whereas other populations experience little or no mortality from ingestion of the toxic toa...
Data
Stomach contents of 4-5 month freshwater crocodiles ( Crocodylus johnstoni ) from Lake Argyle, Western Australia. (XLS)
Article
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Animals almost always use habitats non-randomly, but the costs and benefits of using specific habitat types remain unknown for many types of organisms. In a large lake in northwestern Australia (Lake Argyle), most hatchling (<12-month-old) freshwater crocodiles (Crocodylus johnstoni) are found in floating vegetation mats or grassy banks rather than...
Article
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Detailed observations on interactions between parasites and prospective hosts during the infection process can clarify (1) the routes by which parasites enter the host and (2) the ability of prospective hosts to detect, avoid, or resist potential parasites. Such information can clarify determinants of host vulnerability. Infective larvae of the nem...
Article
The introduction of invasive alien predators often has catastrophic effects on populations of naïve native prey, but in situations where prey survive the initial impact a predator may act as a strong selective agent for prey that can discriminate and avoid it. Using two common species of Australian small mammals that have persisted in the presence...
Article
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For endangered species that persist as apparently isolated populations within a previously more extensive range, the degree of genetic exchange between those populations is critical to conservation and management. A lack of gene flow can exacerbate impacts of threatening processes and delay or prevent colonization of sites after local extirpation....
Article
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Predation on eggs is an important source of mortality for many long-lived organisms, but causes of egg mortality from specific predators remain poorly known in most cases. Understanding the identity of predators, and the rates and determinants of their effects on a cohort of recruits, can provide a valuable background for attempts to exploit, contr...
Article
The invasion of cane toads (Rhinella marina) through Australia imperils native predators that are killed if they consume these toxic anurans. The magnitude of impact depends upon the predators’ capacity for aversion learning: toad impact is lower if predators can learn not to attack toads. In laboratory trials, we assessed whether bluetongue lizard...
Article
In oviparous species lacking parental care, successful reproduction depends on females selecting nest sites that facilitate embryonic development. Such sites may be limited in the environment, which can lead to multiple females using the same nest site simultaneously. However, there are several alternative explanations for communal nesting, includi...
Article
Summary  In many ecosystems, increases in vegetation density and the resulting closure of forest canopies are threatening the viability of species that depend upon open, sunlight-exposed habitats. Consequently, we need to develop management strategies that recreate open habitats while minimizing the impacts on non-target areas. Selective logging cr...
Article
Predicting the ecological impacts of invasive species on native fauna is a formidable chal-lenge for conservation biologists. One way to deal with that challenge is to stage encounters between the invader and native species in the laboratory, to illuminate likely outcomes of en-counters in the wild. The invasion of the highly toxic cane toad Rhinel...
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Many biological invasions do not occur as a gradual expansion along a continuous front, but result from the expansion of satellite populations that become established at 'invasion hubs'. Although theoretical studies indicate that targeting control efforts at invasion hubs can effectively contain the spread of invasions, few studies have demonstrate...
Article
Humans are rapidly altering natural systems, leading to changes in the distribution and abundance of species. However, so many changes are occurring simultaneously (e.g., climate change, habitat fragmentation) that it is difficult to determine the cause of population fluctuations from correlational studies. We used a manipulative field experiment t...
Article
The arrival of a toxic invasive species may impose selection on local predators to avoid consuming it. Feeding responses may be modified via evolutionary changes to behaviour, or via phenotypic plasticity (e.g. learning, taste aversion). The recent arrival of cane toads (Bufo marinus) in the Northern Territory of Australia induced rapid aversion le...