Due to Reproductive Isolation, a New Species of Weaver Bird

question 49

Multiple Choice

Due to reproductive isolation, a new species of weaver bird is evolving.Is it likely to use a social or solitary nesting strategy?

• A)It depends on whether it lives in the forest or the open savanna.
• B)It depends on whether it lives in near water or near the desert.
• C)It depends on how many similar species it is competing with.
• D)It depends on how many eggs it lays. African weaver birds, which construct nests from vegetation, provide an excellent example of the relationship between ecology and social organization.Their roughly 90 species can be divided according to the type of social group they form.One group of species lives in the forest and builds camouflaged, solitary nests.Males and females are monogamous; they forage for insects to feed their young.The second group of species nests in colonies in trees on the savanna.They are polygynous and feed in flocks on seeds.The feeding and nesting habits of these two groups of species are correlated with their mating systems.In the forest, insects are hard to find, and both parents must cooperate in feeding the young.The camouflaged nests do not call the attention of predators to their brood.On the open savanna, building a hidden nest is not an option.Rather, savanna-dwelling weaver birds protect their young from predators by nesting in trees, which are not very abundant.This shortage of safe nest sites means that birds must nest together in colonies.Because seeds occur abundantly, a female can acquire all the food needed to rear young without a male's help.The male, free from the duties of parenting, spends his time courting many females-a polygynous mating system.

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