Big rattlesnakes which for years have sunned their diamond-patterned backs on the rocks in at least three known dens in the vicinity of Reno are gone this year.

To where, why and when the snakes left their ancestral homes no one knows, although many hunters and fishermen have noted their absence.

At the point known as the Black Nipple, in Dog valley a mile and a half from the Dog valley summit, a large rattlesnake family made its home for years. They are gone.

On the bluff on the south side of the Truckee river above the headgate at Fleish, big rock, or "timber," rattlers grew to a length of five and six feet and reared scores of their progeny in undisturbed surroundings. These, too, have disappeared.

Near Mystic, in a point of rooks adjoining "Rattlesnake Hole" in the river, where fishermen were accused to be alert for the buzz of the rattlers, there were no warning signs this season.

Some attribute the lack of snakes to the dynamiting operations carried on while the Truckee River highway was being built, which might serve to cause the rattlers to flee the unseen enemy which rocked their home.

The more plausible theory, however, advanced by Jack Bell, Verdi naturalist, is that the apparent migration of the rattlesnakes is due to the shortage of food. He points out that the failure of springs and creeks during the past dry season has dried up the green spots and driven out the squirrels, field-mice and young rabbits on which the big diamond backs are accustomed to feed.