scholarly journals Increased rates of dispersal of free-ranging cane toads (Rhinella marina) during their global invasion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Richard Shine ◽  
Ross A. Alford ◽  
Ryan Blennerhasset ◽  
Gregory P. Brown ◽  
Jayna L. DeVore ◽  
...  
Keyword(s):  
French Guiana ◽  
Native Range ◽  
Rhinella Marina ◽  
Range Edge ◽  
Population Spread ◽  
Eastern Australia ◽  
Tropical Australia ◽  
Free Ranging ◽  
Global Invasion ◽  
Daily Changes

AbstractInvasions often accelerate through time, as dispersal-enhancing traits accumulate at the expanding range edge. How does the dispersal behaviour of individual organisms shift to increase rates of population spread? We collate data from 44 radio-tracking studies (in total, of 650 animals) of cane toads (Rhinella marina) to quantify distances moved per day, and the frequency of displacement in their native range (French Guiana) and two invaded areas (Hawai’i and Australia). We show that toads in their native-range, Hawai’i and eastern Australia are relatively sedentary, while toads dispersing across tropical Australia increased their daily distances travelled from 20 to 200 m per day. That increase reflects an increasing propensity to change diurnal retreat sites every day, as well as to move further during each nocturnal displacement. Daily changes in retreat site evolved earlier than did changes in distances moved per night, indicating a breakdown in philopatry before other movement behaviours were optimised to maximise dispersal.

scholarly journals Spatial ecology of cane toads (Rhinella marina) in their native range: a radiotelemetric study from French Guiana

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jayna L. DeVore ◽  
Richard Shine ◽  
Simon Ducatez
Keyword(s):  
Invasive Species ◽  
Body Condition ◽  
Spatial Ecology ◽  
French Guiana ◽  
Source Region ◽  
Behavioural Flexibility ◽  
Native Range ◽  
Environmental Niche ◽  
Rhinella Marina ◽  
Free Ranging

AbstractLike most invasive species, cane toads have attracted less research in their native range than in invaded areas. We radio-tracked 34 free-ranging toads in French Guiana, a source region for most invasive populations, across two coastal and two rainforest sites. Coastal toads generally sheltered in pools of fresh or brackish water but nocturnally foraged on beaches, whereas rainforest toads sheltered in forested habitats, moving into open areas at night. Over five days of monitoring, native toads frequently re-used shelters and moved little between days (means = 10–63 m/site) compared to invasion-front toads from Australia (~ 250 m). Larger toads moved less between days, but displaced in more consistent directions. At night, foraging toads travelled up to 200 m before returning to shelters. Foraging distance was related to body condition at coastal sites, with toads in poorer body condition travelling farther. Rain increased the probability of coastal toads sheltering in the dry habitats where they foraged. Dispersal and rainfall were lower at coastal sites, and the strategies utilized by coastal toads to minimize water loss resembled those of invasive toads in semi-desert habitats. This global invader already exhibits a broad environmental niche and substantial behavioural flexibility within its native range.

scholarly journals Long distance homing in the cane toad (Rhinella marina) in its native range

2021 ◽  
Author(s):  
Daniel A. Shaykevich ◽  
Andrius Pašukonis ◽  
Lauren A. O'Connell
Keyword(s):  
Life Histories ◽  
Site Fidelity ◽  
French Guiana ◽  
Spatial Behavior ◽  
Native Range ◽  
Short Term ◽  
Long Distance ◽  
Amphibian Species ◽  
Rhinella Marina ◽  
Current Paradigm

Many animals exhibit complex navigation over different scales and environments. Navigation studies in amphibians have largely focused on species with life histories that require accurate spatial movements, such as territorial poison frogs and migratory pond-breeding amphibians that show fidelity to mating sites. However, other amphibian species have remained relatively understudied, leaving open the possibility that well-developed navigational abilities are widespread. Here, we measured short-term space use in non-territorial, non-migratory cane toads (Rhinella marina) in their native range in French Guiana. After establishing site fidelity, we tested their ability to return home following translocations of 500 and 1000 meters. Toads were able to travel in straight trajectories back to home areas, suggesting navigational abilities similar to those observed in amphibians with more complex spatial behavior. These observations break with the current paradigm of amphibian navigation and suggest that navigational abilities may be widely shared among amphibians.

Encounters between freshwater crocodiles and invasive cane toads in north-western Australia: does context determine impact?

2020 ◽  
Vol 41 (1) ◽  
pp. 94-101
Author(s):  
Gregory S Clarke ◽  
Cameron M Hudson ◽  
Richard Shine
Keyword(s):  
Western Australia ◽  
French Guiana ◽  
Native Range ◽  
Taste Aversion Learning ◽  
Rhinella Marina ◽  
Physiological Tolerance ◽  
Crocodylus Johnstoni ◽  
A Site ◽  
Riverine Systems ◽  
North Western

ABSTRACT The potent defensive chemicals of cane toads (Rhinella marina) protect them against predators that lack coevolved physiological tolerance to those toxins. That relative invulnerability may explain why major injuries (such as limb loss) appear to be rare in cane toads from most of their global range; however, we noted frequent predator-induced injuries (>4% of adults) in samples from within the toad’s native range (in French Guiana) and from a site (Lake Argyle) in north-western Australia. Toads at Lake Argyle enter the edge of the lake at night to rehydrate, exposing them to foraging freshwater crocodiles (Crocodylus johnstoni). Crocodiles rarely consume toads, but the attacks often result in loss of a limb. Because limbs contain relatively little toxin, attacks to the limbs expose a crocodile to nauseating but non-lethal amounts of toxin; and hence, facilitate taste aversion learning by the predator. The context of the encounters, such as differences in geography, may help to explain why the invasion of cane toads has not significantly impacted on crocodile populations at this site, in contrast to heavy impacts reported from nearby riverine systems.

scholarly journals Long distance homing in the cane toad (Rhinella marina) in its native range

2021 ◽  
Author(s):  
Daniel A Shaykevich ◽  
Andrius Pasukonis ◽  
Lauren A O'Connell
Keyword(s):  
Home Range ◽  
Life Histories ◽  
French Guiana ◽  
Spatial Behavior ◽  
Native Range ◽  
Cane Toad ◽  
Short Term ◽  
Long Distance ◽  
Rhinella Marina ◽  
Current Paradigm

Many animals exhibit complex navigation over different scales and environments. Navigation studies in amphibians have largely focused on species with life histories that require advanced spatial capacities, such as territorial poison frogs and migratory pond-breeding amphibians that show fidelity to mating sites. However, other species have remained relatively understudied, leaving the possibility that well-developed navigational abilities are widespread. Here, we measured short-term space use in non-territorial, non-migratory cane toads (Rhinella marina) in their native range in French Guiana. After establishing home range, we tested their ability to return to home following translocations of 500 and 1000 meters. Toads were able to travel in straight trajectories back to home areas, suggesting map-like navigational abilities similar to those observed in amphibians with more complex spatial behavior. These observations break with the current paradigm of amphibian navigation and suggest that navigational abilities may be widely shared among amphibians.

Uraba lugens (eucalypt leaf skeletonizer).

2021 ◽  
Author(s):  
Lisa Berndt
Keyword(s):  
New Zealand ◽  
Western Australia ◽  
Timber Production ◽  
Native Range ◽  
Natural Forests ◽  
Eastern Australia ◽  
Important Pest ◽  
Eucalypt Forests

Abstract U. lugens was first considered a serious pest of natural eucalypt forests in Western Australia in 1983 when the first severe outbreak occurred there (Strelein, 1988). Prior to that it was widely known as a pest of eucalypt forests in eastern Australia (Campbell, 1962; Harris, 1974). As these natural forests are or were managed for timber production, it is considered an economically important pest in its native range. Damage to amenity trees is also a common problem, although few trees are killed by this defoliation (Anonymous, 1979).U. lugens was recorded as invasive in New Zealand by Crabtree (1997). In its exotic range it has become a significant pest of amenity trees, particularly Lophestemon confertus (Australian brush box), which is commonly planted in some parts of Auckland City (Kriticos et al., 2007).

Precision, accuracy and bias of walked line-transect distance sampling to estimate eastern grey kangaroo population size

2015 ◽  
Vol 42 (8) ◽  
pp. 633 ◽  
Author(s):  
Ruth Glass ◽  
David M. Forsyth ◽  
Graeme Coulson ◽  
Marco Festa-Bianchet
Keyword(s):  
Population Size ◽  
Distance Sampling ◽  
Accurate Method ◽  
Line Transect ◽  
Good Precision ◽  
Design Elements ◽  
Abundance Estimates ◽  
Grey Kangaroo ◽  
Eastern Australia ◽  
Free Ranging

Context Distance sampling is widely used to estimate the size of wildlife populations, including kangaroos. However, the performance of distance-sampling abundance estimates has seldom been evaluated for wild mammal populations of known size. Aims We evaluated the precision, accuracy, bias and interval coverage of abundance estimates from walked line-transect sampling, a commonly used distance-sampling method, for a marked free-ranging population of eastern grey kangaroos (Macropus giganteus) at Yanakie Isthmus, Wilsons Promontory National Park, south-eastern Australia. Methods In each of two study periods (November 2012 and May 2013) we first determined the true size of the uniquely marked kangaroo population by conducting 10 intensive searches of the study area. We then conducted distance sampling along six systematically spaced line transects. We walked each transect four times in November 2012 and seven times in May 2013. Data were analysed using Program DISTANCE. Key results Our intensive searches revealed that 141 and 124 collared kangaroos were present in the study area in November 2012 and May 2013, respectively. When transects were walked four or more times (i.e. ≥400 observations), maximum precision (coefficient of variation; CV of ~13%) was achieved in both survey periods. Walking transects twice (i.e. ~200 observations) produced abundance estimates with CVs of <20% in each study period. The accuracy (root mean square error) of abundance estimates varied from 1 to 13 (November 2012) and from 3 to 28 (May 2013). Bias ranged from −9% to +23%, but stabilised at between −1% and −9% when transects were walked four or more times in each study period. The 95% confidence intervals for the abundance estimates always included the true population size. Conclusions Our results indicated that walked line-transect distance sampling is a precise and accurate method for estimating eastern grey kangaroo abundance. The small negative biases that occurred when sample sizes were large were likely to be due to some animals moving outside the study area. Implications Provided that the key design elements and assumptions are met, estimates of kangaroo abundance from walked line-transect distance sampling should have good precision (CV < 20%) and minimal (<10%) bias.

An introduced pentastomid parasite (Raillietiella frenata) infects native cane toads (Rhinella marina) in Panama

Parasitology ◽  
2014 ◽  
Vol 142 (5) ◽  
pp. 675-679 ◽  
Author(s):  
CRYSTAL KELEHEAR ◽  
KRISTIN SALTONSTALL ◽  
MARK E. TORCHIN
Keyword(s):  
Central America ◽  
First Record ◽  
Host Shift ◽  
Native Range ◽  
Host Switch ◽  
Rhinella Marina ◽  
Introduced Populations ◽  
A Site ◽  
Hemidactylus Frenatus

SUMMARYThe pentastomid parasite, Raillietiella frenata, is native to Asia where it infects the Asian House gecko, Hemidactylus frenatus. This gecko has been widely introduced and recently R. frenata was found in introduced populations of cane toads (Rhinella marina) in Australia, indicating a host-switch from introduced geckos to toads. Here we report non-native adult R. frenata infecting the lungs of native cane toads in Panama. Eight of 64 toads were infected (median = 2·5, range = 1–80 pentastomids/toad) and pentastomid prevalence was positively associated with the number of buildings at a site, though further sampling is needed to confirm this pattern. We postulate that this pattern is likely due to a host shift of this parasite from an urban-associated introduced gecko. This is the first record of this parasite infecting cane toads in their native range, and the first instance of this parasite occurring in Central America.

scholarly journals Embryonic exposure to conspecific chemicals suppresses cane toad growth and survival

2011 ◽  
Vol 8 (2) ◽  
pp. 226-229 ◽  
Author(s):  
Michael R. Crossland ◽  
Richard Shine
Keyword(s):  
Chemical Cues ◽  
Ecological Impacts ◽  
Cane Toad ◽  
Growth And Survival ◽  
Rhinella Marina ◽  
Embryonic Exposure ◽  
Body Sizes ◽  
Tropical Australia ◽  
Survival And Growth ◽  
Invasive Taxa

Adaptations to suppress the viability of conspecifics may provide novel ways to control invasive taxa. The spread of cane toads ( Rhinella marina ) through tropical Australia has had severe ecological impacts, stimulating a search for biocontrol. Our experiments show that cane toad tadpoles produce waterborne chemical cues that suppress the viability of conspecifics encountering those cues during embryonic development. Brief (72 h) exposure to these cues in the egg and post-hatching phases massively reduced rates of survival and growth of larvae. Body sizes at metamorphosis (about three weeks later) were almost twice as great in control larvae as in tadpole-exposed larvae. The waterborne cue responsible for these effects might provide a weapon to reduce toad recruitment within the species' invaded range.

scholarly journals Geographic Spread ofGnamptogenys triangularis(Hymenoptera: Formicidae: Ectatomminae)

2012 ◽  
Vol 2012 ◽  
pp. 1-4
Author(s):  
Joseph A. MacGown ◽  
James K. Wetterer
Keyword(s):  
Costa Rica ◽  
Central America ◽  
French Guiana ◽  
Buenos Aires ◽  
South American ◽  
Native Range ◽  
Southeastern Usa ◽  
The North ◽  
Geographic Spread ◽  
Major Pest

Gnamptogenys triangularis(Mayr), native to the forests of South and Central America, is a predatory ant that feeds on millipedes. In its native range, this species is known from Buenos Aires, Argentina (38.1°S) in the south to Costa Rica (10.4°N) in the north, with records from eight countries in South America (all except Chile, French Guiana, and Paraguay), and the two southernmost countries of Central America (Panama and Costa Rica). The first records ofG. triangularisoutside its native range came from Florida beginning in 1985 (six sites: 25.5°–30.4°N) and Alabama in 1996 (one site: 30.4°N). Here we present the first records ofG. triangularisfrom Mississippi, dating from 2002–2010 (five sites: 30.5°–31.2°N). Based on its South American range, it appears thatG. triangularishas the potential to spread to forests throughout much of the southeastern USA. There are no documented impacts ofG. triangularis,and it seems unlikely that this species will ever become a major pest.

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