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Although the fruit of the Russian olive is eaten by some wildlife species, the tree's foliage is too open to provide good nesting cover for birds. pheasant. I didn't even see or hear a house wren." Compared to what it should have been, the place was dead. Wild animals need more than just greenery just as they need more than food alone. This is the tragedy of Russian olive. For 60 years the Russian olive has been the tree of choice on Colorado's plains. Tolerating drought, temperature extremes and poor soil, Russian olive was favored for windbreaks and shelter- belts. Various private groups and gov- ernment agencies promoted the Russian olive and even subsidized its planting since the dry, dusty years of the 1930s. Many mammals, including rock squirrels, fox squirrels, raccoons, mule and white-tailed deer, even coyotes and red foxes, eat the pithy fruits copiously produced by Russian olives. Robins, starlings, cedar and Bohemian wax- wings, even ring-necked pheasants and the occasional mallard readily consume Russian olive fruits. The tree, which is in the oleaster, not the olive family, would seem to be ideal. Nothing, however, serves so well as the perspective of time. Fritz Knopf, an ornithologist and research biologist with the National Ecology Research Center of the May/June 1991 USFWS, studied Russian olive for a calmly, "you have a pure stand of Rus- decade. He draws entirely different con- sian olive dominating the riparian com- clusions about this exotic. munity. " "The tree really isn't any good for The tree so long promoted as the tree birds:' Knopf advises. "Woodpeckers of choice for wildlife habitat actually don't excavate the hard wood, so you get reduces plant and animal diversity. Con- no cavity-nesters in Russian olive; and servationists did not get what they bar- the foliage is so open that it affords very gained for. poor nesting cover, so you don't get the As bad as Russian olive may be, its open-nest species, either. It also has less disvalue is exceeded by another exotic insect burden and diversity than other tree, the tamarisk. '. hard woods, so you don't get the insec- Originally from the arid environs of tivorous birds:' the Mediterranean Sea, tamarisk was So, although various wildlife species brought to North America as an consume Russian olive fruits, other life ornamental. It quickly escaped cultiva- needs are not provided by the tree. The tion and in over a century hasn't yet tragedy builds. stopped spreading. During the 19705, "What happens:' explains Knopf, "is several studies in Arizona showed the Russian olive gradually takes over. It tree diminishes bird diversity. More invades riparian forests and frequently recent discoveries bring the hazard grows in a band or strip between the closer to home. cottonwoods and water's edge. Shade "We've discovered that tamarisk from the cottonwoods suppresses the growing along riverbanks narrows the olives initially; but eventually, the big river channel, " says Ed Wick, a fisher- old cottonwoods die, opening the ies consultant who has spent years canopy. studying the endangered fishes of the "The Russian olive responds to the Colorado River system in western open canopy with explosive growth. Colorado. Cottonwo~d" nppn mn;c;t "ni~9nd nirP('~ "When tamarisk gets established _ I he ussian olives sha e the soil, along the banks, it captures silt that fills precluding cottonwood regeneration. the shallow backwaters where larval "Within a few years," Knopf says squawfish ordinarily develop. Those f('Y)k./e... Ar,',v t)c.ettatllwocJ r~~(jr.t/~"/ ~"D~S ? ;1 13