Armadillo Decline

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   The armadillo family shows all the signs of being in decline. Its range is restricted to tropical and subtropical America. The living species are few and specialized in habit, being limited to running and digging. There are no climbers or swimmers. The largest living species, the giant armadillo, is dwarfed by the fossilarmadillo2.jpg (5633 bytes) glyptodon that stood 5 feet high. If no more, this suggests a dying down in the adaptability in the race as a whole. The fairy armadillo, perhaps the most specialized, is also the most restricted. Its final stronghold in the sandy plains of Argentina is now being threatened by expanding agriculture.

   Although the armadillos seem to be declining, and everything points to this, one species is actively extending its range. This is the nine-banded armadillo. In 1880 it lived little farther north than the Lower Rio Grande Valley on the borders of the armadillo4.jpg (1898 bytes)United States and Mexico. By 1905 it had moved into the western half of Texas as far as the Colorado River. Since then it has moved across to Kansas and Missouri. Its has occasionally been found in New Mexico and Oklahoma but has not become firmly established. It has been introduced to Florida.

   Why this sudden  burst of life should have occured is not known. There is little sign that the nine-banded armadillo is enjoying especial freedom from enemies, abundance of food or a rapid rate of breeding. Rather the reverse is true. Usually a zoological group, like an individual, reaches a peak of development, then declines. There are, however, one or two examples from the fossil record suggesting that groups may take on a new lease of life.

 

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