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Effect of an invasive plant and moonlight on rodent foraging behavior in a coastal dune ecosystem.

Johnson MD, De León YL - PLoS ONE (2015)

Bottom Line: We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat.There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase.This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats.

View Article: PubMed Central - PubMed

Affiliation: Department of Wildlife, Humboldt State University, Arcata, California, 95521, United States of America.

ABSTRACT
Understanding how invasive plants may alter predator avoidance behaviors is important for granivorous rodents because their foraging can trigger ripple effects in trophic webs. Previous research has shown that European beach grass Ammophila arenaria, an invasive species in coastal California, affects the predation of other seeds by the rodents Microtus californicus, Peromyscus maniculatus, and Reithrodontomys megalotis. This may be due to lower perceived predation risk by rodents foraging in close proximity to the cover provided by Ammophila, but this mechanism has not yet been tested. We examined the perceived predation risk of rodents by measuring the 'giving up density' of food left behind in experimental patches of food in areas with and without abundant cover from Ammophila and under varying amount of moonlight. We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat. There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase. Our findings illustrate that foraging rodents, well known to be risk-averse during moonlit nights, are also affected by the presence of an invasive plant. This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats. Future research in this system should work to unravel the complex trophic links formed by a non-native invasive plant (i.e., Ammophila) providing cover favored by native rodents, which likely forage on and potentially limit the recruitment of native and non-native plants, some of which have ecosystem consequences of their own.

No MeSH data available.


Related in: MedlinePlus

Effect of habitat and moonlight on giving up density.Mean (±1 SE) nocturnal giving-up-density of food (GUD) left behind on feeding stations deployed in Ammophila-dominated and restored habitats in the coastal dunes of Northwestern California, June-July 2011. The experiment was run under three moonlight conditions based on the number of lunar-minutes (product of fractional moon illumination and the number of minutes the moon was above the horizon after the end of civil twilight and before the onset of twilight the following morning): low moonlight (116.4), intermediate moonlight (155.0), and high moonlight (176.8).
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pone.0117903.g002: Effect of habitat and moonlight on giving up density.Mean (±1 SE) nocturnal giving-up-density of food (GUD) left behind on feeding stations deployed in Ammophila-dominated and restored habitats in the coastal dunes of Northwestern California, June-July 2011. The experiment was run under three moonlight conditions based on the number of lunar-minutes (product of fractional moon illumination and the number of minutes the moon was above the horizon after the end of civil twilight and before the onset of twilight the following morning): low moonlight (116.4), intermediate moonlight (155.0), and high moonlight (176.8).

Mentions: A two-way ANOVA revealed strong effects of habitat, lunar-minutes, and their interaction on GUD (Table 2). Overall, there was a significant main effect of habitat, with higher GUDs in the restored than in the Ammophila-dominated habitat, consistent with the hypothesis that perceived predation risk diminishes with abundant cover. The main effect of lunar-minutes was also significant, with GUDs highest at intermediate values and the lowest GUDs on nights with low lunar-minutes. There also was a strongly significant interaction between habitat and lunar-minutes; GUD was lower in Ammophila (lower predation risk) only when the number of lunar minutes was intermediate or high (Fig. 2).


Effect of an invasive plant and moonlight on rodent foraging behavior in a coastal dune ecosystem.

Johnson MD, De León YL - PLoS ONE (2015)

Effect of habitat and moonlight on giving up density.Mean (±1 SE) nocturnal giving-up-density of food (GUD) left behind on feeding stations deployed in Ammophila-dominated and restored habitats in the coastal dunes of Northwestern California, June-July 2011. The experiment was run under three moonlight conditions based on the number of lunar-minutes (product of fractional moon illumination and the number of minutes the moon was above the horizon after the end of civil twilight and before the onset of twilight the following morning): low moonlight (116.4), intermediate moonlight (155.0), and high moonlight (176.8).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4334550&req=5

pone.0117903.g002: Effect of habitat and moonlight on giving up density.Mean (±1 SE) nocturnal giving-up-density of food (GUD) left behind on feeding stations deployed in Ammophila-dominated and restored habitats in the coastal dunes of Northwestern California, June-July 2011. The experiment was run under three moonlight conditions based on the number of lunar-minutes (product of fractional moon illumination and the number of minutes the moon was above the horizon after the end of civil twilight and before the onset of twilight the following morning): low moonlight (116.4), intermediate moonlight (155.0), and high moonlight (176.8).
Mentions: A two-way ANOVA revealed strong effects of habitat, lunar-minutes, and their interaction on GUD (Table 2). Overall, there was a significant main effect of habitat, with higher GUDs in the restored than in the Ammophila-dominated habitat, consistent with the hypothesis that perceived predation risk diminishes with abundant cover. The main effect of lunar-minutes was also significant, with GUDs highest at intermediate values and the lowest GUDs on nights with low lunar-minutes. There also was a strongly significant interaction between habitat and lunar-minutes; GUD was lower in Ammophila (lower predation risk) only when the number of lunar minutes was intermediate or high (Fig. 2).

Bottom Line: We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat.There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase.This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats.

View Article: PubMed Central - PubMed

Affiliation: Department of Wildlife, Humboldt State University, Arcata, California, 95521, United States of America.

ABSTRACT
Understanding how invasive plants may alter predator avoidance behaviors is important for granivorous rodents because their foraging can trigger ripple effects in trophic webs. Previous research has shown that European beach grass Ammophila arenaria, an invasive species in coastal California, affects the predation of other seeds by the rodents Microtus californicus, Peromyscus maniculatus, and Reithrodontomys megalotis. This may be due to lower perceived predation risk by rodents foraging in close proximity to the cover provided by Ammophila, but this mechanism has not yet been tested. We examined the perceived predation risk of rodents by measuring the 'giving up density' of food left behind in experimental patches of food in areas with and without abundant cover from Ammophila and under varying amount of moonlight. We found strong evidence that giving up density was lower in the thick uniform vegetation on Ammophila-dominated habitat than it was in the more sparsely and diversely vegetated restored habitat. There was also evidence that moonlight affected giving up density and that it mediated the effects of habitat, although with our design we were unable to distinguish the effects of lunar illumination and moon phase. Our findings illustrate that foraging rodents, well known to be risk-averse during moonlit nights, are also affected by the presence of an invasive plant. This result has implications for granivory and perhaps plant demography in invaded and restored coastal habitats. Future research in this system should work to unravel the complex trophic links formed by a non-native invasive plant (i.e., Ammophila) providing cover favored by native rodents, which likely forage on and potentially limit the recruitment of native and non-native plants, some of which have ecosystem consequences of their own.

No MeSH data available.


Related in: MedlinePlus