Suppose you are in charge of planning a forest reserve, and one of your main goals is to help sustain locally beleaguered populations of woodland birds. Parasitism by the brown-headed cowbird is an escalating problem in the area. Reading research reports, you note that female cowbirds are usually reluctant to penetrate more than about 100 m into a forest and that some woodland birds are known to reduce cowbird nest parasitism by restricting their nesting to the denser, more central regions of forests. The forested area you have to work with is about 1,000 m by 6,000 m. A recent logging operation removed about half of the trees on one of the 6,000 m sides; the other sides are adjacent to deforested pastureland. Your plan must include space for a small maintenance building, which you estimate to take up about 100 m2. It will also be necessary to build a road, 10 m by 1,000 m, across the reserve. Where would you contrast the road and the building, and why?
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I would construct the building within 200 m from the side near to the logging area and the road across the reserve within 110 m from the side of the deforested pastureland. This would help reduce the problem of parasitism by the brown-headed cowbirds by separating them from the woodland birds. Because the road would be built within 110 m from the side of the deforested pastureland, the female cowbirds, the more parasitic sex, would no longer be able to gain access to the nests of the woodland birds. The division of the two species would ultimately help sustain the population of woodland birds, thus achieving the major goal of the reserve.
I would construct the building within 200 m from the side near to the logging area, and I would construct the road across the reserve within 110 m from the side of the deforested pastureland. Constructing the building within 200 m from the side near to the logging area would help the ecosystem as a whole by not destroying any more of the natural habitat. Constructing the road within 110 m from the side of the deforested pastureland would help reduce the problem of parasitism by the brown-headed cowbirds by separating them from the majority of the woodland birds. Because the road would be built within 110 m from the side of the deforested pastureland, the road would serve as a sort of “barrier,” and the female cowbirds, the more parasitic sex, would no longer be able to gain access to the interior nests of the woodland birds. Since cowbirds usually forage in open fields on insects attracted to cattle and other large herbivores, they would still be able to survive near the deforested pastureland, where there is more edge habitat and open land for cattle, horses, and sheep. The division of the two species would ultimately help sustain both the population of woodland birds and the overall biodiversity of the ecosystem, thus achieving the major goal of the reserve.
You've written an excellent answer. Both the cowbirds and the woodland birds have their habitats protected.
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