Join park naturalists for an introduction to astronomy and a look at the night sky at 7 p.m., Thursday, Jan. 6. Telescopes and binoculars will be available. Reservations are required. Join naturalists Vicki Powers and Ralph Terry for a walk in search of desert birds at 9 a.m., Friday, Jan. 7, and Tuesday, Jan. 11. Learn how plants and animals adapt to life in the desert at 10 a.m., Friday, Jan. 7. Take a stroll through the desert at sunset at 5 p.m., Saturday, Jan. 8. Explore the life cycles of the saguaro cactus and the changing face of its Sonoran Desert home on a walk at 2 p.m., every Sunday. Events are free with a park-use fee of $10 per vehicle; or $5 for bicyclists or pedestrians. Call for reservations or more information.