By this time, many reasons for the reduction in the grebe population have been examined. Although the natives supplement their diet with birds occasionally, hunting of these birds is not likely. They are too quick for the traps and slingshots the natives use to hunt other birds. Guatemalan law forbids ownership of firearms, so they are not being shot. The harvest of reeds and tul is happening at no greater rate recently than in the past. Population increases by other birds have not been noticed in recent years. Mayan farmers do not normally use fertilizers or pesticides in amounts that could run off their cornfields to pollute the lake. Not enough is known about these secretive birds to determine whether disease or parasites could be involved at this time.
The pied-billed grebe, which is widespread over much of North and Central America, colonized the lake in 1965. This grebe and the giant grebe may be two varieties of the same species. The two birds look much alike, but the native one is distinctly larger and has slightly different markings. This new grebe also has small wings, making take-off difficult, but it does fly. Presumably some birds landed on the lake one day, liked it, and stayed.
The black bass is such a fierce predator that it has caught and killed birds such as swallows, warblers, and red-winged blackbirds as they fly near the surface of the water. The intestines of a couple of the larger bass have been opened to determine their feeding habits. As expected, they have been eating smaller fish, frogs, snails, crabs, and insects. Their intestines also contain skeletons of young birds. The role of the bass in the disappearance of the grebe needs to be studied more thoroughly.
Go to Historic Update IV—"The Lake's Populations Have Decreased"
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