Page:Popular Science Monthly Volume 77.djvu/172

166 valuable as we know how, to the ecologist as well as the systematist. It is quite probable that the facts of distribution, life history, and economic status may finally prove to be of more far-reaching value, than whatever information is obtainable exclusively from the specimens themselves.

At this point I wish to emphasize what I believe will ultimately prove to be the greatest value of our museum. This value will not, however, be realized until the lapse of many years, possibly a century, assuming that our material is safely preserved. And this is that the student of the future will have access to the original record of faunal conditions in California and the west wherever we now work. He will know the proportional constituency of our faunas by species, the relative numbers of each species and the extent of the ranges of species as they exist to-day.

Perhaps the most impressive fact brought home to the student of geographical distribution, as he carries on his studies, is the profound change that is constantly going on in the faunal make-up of our country. Eight now are probably beginning changes to be wrought in the next few years vastly more conspicuous than those that have occurred in ten times that length of time preceding. The effects of deforestation, of tree-planting on the prairies, of the irrigation and cultivation of the deserts, all mean the rapid shifting of faunal boundaries, the extension of ranges of some animals, restriction in the ranges of others, and, with no doubt whatever, the complete extermination of many others, as in a few cases already on record.

If we now had the accurate record of faunal conditions as they were in the Atlantic states a century ago, how much might we not be able to adduce from a study of the changes which have taken place. Now is the opportunity to make such records in our western region. Comparative studies of conditions in the same area at different successive times is bound to bring important generalizations in the field of evolution. It will be seen here how valuable also will prove the collections preserved at corresponding intervals. Changes in conditions will doubtless bring about changes in the habits and physical characters of the animals enduring them.

Another grave danger from the standpoint of the student of natural speciation lies in the introduction of exotic animals. This evil is growing rapidly in the effort to restock regions with more hardy or prolific game animals. If successful from the sportsman's basis, either of two things will happen: the original, native species will become extinct by competitive replacement, or, where the relationships are close, crossing will take place so that the original species will be spoiled through hybridization. There are already instances of both in different sections of the United States. It is highly desirable that a good