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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

Microhabitat selection by toads on Hawai’i.Figure shows microhabitat use of 40 radio-tracked and spool-tracked cane toads on the island of Hawai’i. The panels show interactions between time (day vs. night) and toad habitat selection (used places vs. nearby available sites that were not used): (a) substrate temperature, as recorded using an infrared thermometer (recorded only by day); (b) the % of bare ground within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; (c) the % of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; and (d) the height of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away. Figure shows mean values and associated standard errors.
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pone.0151700.g004: Microhabitat selection by toads on Hawai’i.Figure shows microhabitat use of 40 radio-tracked and spool-tracked cane toads on the island of Hawai’i. The panels show interactions between time (day vs. night) and toad habitat selection (used places vs. nearby available sites that were not used): (a) substrate temperature, as recorded using an infrared thermometer (recorded only by day); (b) the % of bare ground within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; (c) the % of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; and (d) the height of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away. Figure shows mean values and associated standard errors.

Mentions: Our surveys yielded an extensive data set on attributes of the microhabitats used by toads, as well as nearby available (but unused) microhabitats. Analysis revealed many non-random patterns. For example, toads were active at night in areas with less bare ground, a more open canopy, less dense understory, and less leaf-litter than were found around their diurnal retreat-sites (Table 2, Fig 4). Similarly, conditions at the place a toad was found differed from those at a nearby randomly-selected (unused) site; toads selected diurnal retreat-sites that gave them access to bare ground, and higher and less dense understory (Table 2, Fig 4). Overall, habitat selection by toads was strongly non-random by day, but not by night (Fig 4).


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)

Microhabitat selection by toads on Hawai’i.Figure shows microhabitat use of 40 radio-tracked and spool-tracked cane toads on the island of Hawai’i. The panels show interactions between time (day vs. night) and toad habitat selection (used places vs. nearby available sites that were not used): (a) substrate temperature, as recorded using an infrared thermometer (recorded only by day); (b) the % of bare ground within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; (c) the % of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; and (d) the height of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away. Figure shows mean values and associated standard errors.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0151700.g004: Microhabitat selection by toads on Hawai’i.Figure shows microhabitat use of 40 radio-tracked and spool-tracked cane toads on the island of Hawai’i. The panels show interactions between time (day vs. night) and toad habitat selection (used places vs. nearby available sites that were not used): (a) substrate temperature, as recorded using an infrared thermometer (recorded only by day); (b) the % of bare ground within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; (c) the % of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away; and (d) the height of understory vegetation within a 1-m quadrat surrounding the toad, compared to a randomly-chosen site 5 m away. Figure shows mean values and associated standard errors.
Mentions: Our surveys yielded an extensive data set on attributes of the microhabitats used by toads, as well as nearby available (but unused) microhabitats. Analysis revealed many non-random patterns. For example, toads were active at night in areas with less bare ground, a more open canopy, less dense understory, and less leaf-litter than were found around their diurnal retreat-sites (Table 2, Fig 4). Similarly, conditions at the place a toad was found differed from those at a nearby randomly-selected (unused) site; toads selected diurnal retreat-sites that gave them access to bare ground, and higher and less dense understory (Table 2, Fig 4). Overall, habitat selection by toads was strongly non-random by day, but not by night (Fig 4).

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