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Toads on Lava: Spatial Ecology and Habitat Use of Invasive Cane Toads (Rhinella marina) in Hawai'i.

Ward-Fear G, Greenlees MJ, Shine R - PLoS ONE (2016)

Bottom Line: Because moist sites are scarce on the highly porous lava substrate, Hawai'ian toads depend on anthropogenic disturbance for shelter (e.g. beneath buildings), foraging (e.g. suburban lawns, golf courses) and breeding (artificial ponds).Foraging sites are further concentrated by a scarcity of flying insects (negating artificial lights as prey-attractors).Cane toads in Hawai'i thrive in scattered moist patches within a severely arid matrix, despite a scarcity of flying insects, testifying to the species' ability to exploit anthropogenic disturbance.

View Article: PubMed Central - PubMed

Affiliation: School of Life and Environmental Sciences, Heydon-Laurence Building A08, University of Sydney, Sydney, New South Wales, Australia.

ABSTRACT
Most ecological research on cane toads (Rhinella marina) has focused on invasive populations in Australia, ignoring other areas where toads have been introduced. We radio-tracked and spool-tracked 40 toads, from four populations on the island of Hawai'i. Toads moved extensively at night (mean 116 m, from spool-tracking) but returned to the same or a nearby retreat-site each day (from radio-tracking, mean distance between successive retreat sites 11 m; 0 m for 70% of records). Males followed straighter paths during nocturnal movements than did females. Because moist sites are scarce on the highly porous lava substrate, Hawai'ian toads depend on anthropogenic disturbance for shelter (e.g. beneath buildings), foraging (e.g. suburban lawns, golf courses) and breeding (artificial ponds). Foraging sites are further concentrated by a scarcity of flying insects (negating artificial lights as prey-attractors). Habitat use of toads shifted with time (at night, toads selected areas with less bare ground, canopy, understory and leaf-litter), and differed between sexes (females foraged in areas of bare ground with dense understory vegetation). Cane toads in Hawai'i thrive in scattered moist patches within a severely arid matrix, despite a scarcity of flying insects, testifying to the species' ability to exploit anthropogenic disturbance.

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Related in: MedlinePlus

Distances moved by toads between diurnal retreats.Figure shows movement distances between successive diurnal shelters made by 40 radio-tracked cane toads on the island of Hawai’i. Data are shown for two sites on the leeward (dry) side of the island, and for two sites on the windward (wet) side.
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pone.0151700.g002: Distances moved by toads between diurnal retreats.Figure shows movement distances between successive diurnal shelters made by 40 radio-tracked cane toads on the island of Hawai’i. Data are shown for two sites on the leeward (dry) side of the island, and for two sites on the windward (wet) side.

Mentions: Three toads moved distances of >100 m overnight (140 m, 140 m, 520 m; all from Dry side 2) but all others selected diurnal retreats that were close to the one used the previous night (Fig 2). The mean distance between successive retreat-sites was 11.1 m (SE = 3.67) if all records were included, and 7.01 m (SE = 1.5) if the three atypically large movements were excluded. In 70% of cases (111 of 158), the toad was found in the same shelter as the previous day. Frequently, multiple toads used the same shelter-site at the same time. The three long-range movements show that toads are capable of dispersing across this harsh landscape. The longest move (520 m) was by a male toad (98 mm SUL, 119 g) on the night it was released. It dispersed across a wide lava flow between greens on the golf course into a small crevice at one edge of the lava flow, and was found in that same crevice every day thereafter for the duration of radio-tracking.


Toads on Lava: Spatial Ecology and Habitat Use of Invasive Cane Toads (Rhinella marina) in Hawai'i.

Ward-Fear G, Greenlees MJ, Shine R - PLoS ONE (2016)

Distances moved by toads between diurnal retreats.Figure shows movement distances between successive diurnal shelters made by 40 radio-tracked cane toads on the island of Hawai’i. Data are shown for two sites on the leeward (dry) side of the island, and for two sites on the windward (wet) side.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814139&req=5

pone.0151700.g002: Distances moved by toads between diurnal retreats.Figure shows movement distances between successive diurnal shelters made by 40 radio-tracked cane toads on the island of Hawai’i. Data are shown for two sites on the leeward (dry) side of the island, and for two sites on the windward (wet) side.
Mentions: Three toads moved distances of >100 m overnight (140 m, 140 m, 520 m; all from Dry side 2) but all others selected diurnal retreats that were close to the one used the previous night (Fig 2). The mean distance between successive retreat-sites was 11.1 m (SE = 3.67) if all records were included, and 7.01 m (SE = 1.5) if the three atypically large movements were excluded. In 70% of cases (111 of 158), the toad was found in the same shelter as the previous day. Frequently, multiple toads used the same shelter-site at the same time. The three long-range movements show that toads are capable of dispersing across this harsh landscape. The longest move (520 m) was by a male toad (98 mm SUL, 119 g) on the night it was released. It dispersed across a wide lava flow between greens on the golf course into a small crevice at one edge of the lava flow, and was found in that same crevice every day thereafter for the duration of radio-tracking.

Bottom Line: Because moist sites are scarce on the highly porous lava substrate, Hawai'ian toads depend on anthropogenic disturbance for shelter (e.g. beneath buildings), foraging (e.g. suburban lawns, golf courses) and breeding (artificial ponds).Foraging sites are further concentrated by a scarcity of flying insects (negating artificial lights as prey-attractors).Cane toads in Hawai'i thrive in scattered moist patches within a severely arid matrix, despite a scarcity of flying insects, testifying to the species' ability to exploit anthropogenic disturbance.

View Article: PubMed Central - PubMed

Affiliation: School of Life and Environmental Sciences, Heydon-Laurence Building A08, University of Sydney, Sydney, New South Wales, Australia.

ABSTRACT
Most ecological research on cane toads (Rhinella marina) has focused on invasive populations in Australia, ignoring other areas where toads have been introduced. We radio-tracked and spool-tracked 40 toads, from four populations on the island of Hawai'i. Toads moved extensively at night (mean 116 m, from spool-tracking) but returned to the same or a nearby retreat-site each day (from radio-tracking, mean distance between successive retreat sites 11 m; 0 m for 70% of records). Males followed straighter paths during nocturnal movements than did females. Because moist sites are scarce on the highly porous lava substrate, Hawai'ian toads depend on anthropogenic disturbance for shelter (e.g. beneath buildings), foraging (e.g. suburban lawns, golf courses) and breeding (artificial ponds). Foraging sites are further concentrated by a scarcity of flying insects (negating artificial lights as prey-attractors). Habitat use of toads shifted with time (at night, toads selected areas with less bare ground, canopy, understory and leaf-litter), and differed between sexes (females foraged in areas of bare ground with dense understory vegetation). Cane toads in Hawai'i thrive in scattered moist patches within a severely arid matrix, despite a scarcity of flying insects, testifying to the species' ability to exploit anthropogenic disturbance.

Show MeSH
Related in: MedlinePlus