Invasion by a non-native ecosystem engineer alters distribution of a native predator
Article first published online: 10 APR 2012
© 2012 Blackwell Publishing Ltd
Diversity and Distributions
Volume 18, Issue 12, pages 1190–1198, December 2012
How to Cite
Cameron, E. K. and Bayne, E. M. (2012), Invasion by a non-native ecosystem engineer alters distribution of a native predator. Diversity and Distributions, 18: 1190–1198. doi: 10.1111/j.1472-4642.2012.00912.x
- Issue published online: 6 NOV 2012
- Article first published online: 10 APR 2012
- Alberta Conservation Association
- Canadian Circumpolar Institute
- Northern Scientific Training Program
- Alberta Sport, Recreation, Parks and Wildlife Foundation
- Natural Sciences and Engineering Research Council Canada Operating Grant to EMB
- Natural Sciences and Engineering Research Council Vanier Canada Graduate Scholarship to EKC
- Alberta Ingenuity Scholarship to EKC
- Biological invasions;
- Dendrobaena octaedra ;
- habitat alteration;
- invasive prey;
- linear feature;
Shifts in diet composition, abundance or distribution of native predators can occur as a result of exotic prey introductions. We examined effects of non-native earthworms and anthropogenic landscape disturbance on habitat selection by the American robin (Turdus migratorius), a generalist predator, at landscape and local levels. We also investigated whether robins could act as vectors of spread for earthworm cocoons (egg cases).
Boreal forest of Alberta, Canada.
We conducted robin and earthworm surveys at campgrounds, well pads, roads, pipelines, seismic lines and forest interiors across northern Alberta. At a subset of paired locations that had similar habitats and anthropogenic disturbance levels, we sampled both robins and earthworms.
Both groups were most likely to occur at campgrounds, well pads and roads. Furthermore, robins were more likely to occur at locations where earthworms were present in our paired local-level surveys. This correlation between robin and earthworm distributions could be due to robins acting as a vector for earthworm spread, rather than robins’ use of earthworms as prey. However, in tests using captive robins, earthworm cocoons did not survive digestion.
Robin and earthworm distributions were correlated, likely due to robins’ use of earthworms as prey. These results suggest exotic prey can strongly influence native predators at both landscape and local levels, with shifts in native predator distributions occurring as a result of spatial variability in exotic prey distributions. Although the impacts of ecosystem engineering by earthworms have been previously demonstrated, our study provides evidence that effects of earthworms can also cascade upwards via trophic interactions.