WASHINGTON, D.C.: Because the most common species sighted in the national parks these days is not bears or eagles or elk but automobiles, Interior Secretary Bruce Babbitt is proposing that tourists make reservations so that the parks can reduce traffic. Speaking from Yosemite National Park on NBC's "Today" show, Babbitt said the reservation system, which could be put in place within two years in most places, is necessary. Efforts to protect the parks from overcrowding have caused numerous shutdowns over the past two years. Yosemite, for example, has been closed at least 11 times since 1995 because of bumper to bumper traffic. While reservations may be one way to keep the Winnebagos at bay, Babbitt suggested public transportation might also help keep the gates open to the millions of visitors who visit the parks annually, many of them for brief drive-throughs.