In a community of ≥3 competing species, one species may also have a positive indirect effect on another by suppressing a third, shared competitor. We examine the potential for similar interactions among Red-cockaded Woodpeckers (Picoides borealis) and two of its cavity kleptoparasites: southern flying squirrels (Glaucomys volans) and Red-bellied Woodpeckers (Melanerpes carolinus). We hypothesized that flying squirrels have a positive indirect effect on Red-cockaded Woodpeckers by suppressing Red-bellied Woodpeckers. We monitored occupancy of Red-cockaded Woodpecker cavities on 16 territories for one year, and then regularly removed flying squirrels from Red-cockaded Woodpecker cavities for one year on eight territories, each paired with a control. We predicted that flying squirrel removal would competitively release Red-bellied Woodpeckers, which in turn would preempt a positive occupancy response by Red-cockaded Woodpeckers. During the removal phase, flying squirrel occupancy decreased 53% on the removal territories relative to controls (0.46 vs. 0.96 cavities occupied per territory), while Red-bellied Woodpecker occupancy increased 46% (1.00 vs. 0.69 cavities per territory). Red-bellied Woodpecker occupancy increased 103% on the removals from July to December of the removal phase, when most Red-cockaded Woodpecker fledglings, potential helpers, and dispersers acquire cavities. Red-cockaded Woodpeckers failed to respond positively to the removals, apparently because Red-bellied Woodpeckers rapidly occupied the evacuated cavities. The results are consistent with the hypothesis that flying squirrels indirectly benefit Red-cockaded Woodpeckers by suppressing Red-bellied Woodpeckers. This indirect effect approximately counterbalanced the direct negative effect of flying squirrels on Red-cockaded Woodpeckers.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 110 • No. 3