Yes, it is entirely safe to travel by subway to the Bronx Zoo. The Zoo is open from 10:00 a.m. to 5:00 p.m. during the week; 10:00 a.m. to 5:30 p.m. on weekends and holidays. These hours are in effect until Nov. 1.The website for the Zoo is www.bronxzoo.com--Rosaleah 

The subways are generally safe ways to travel, especially during rush hour (7am - 10 am and then again in the evenings, 6pm to 10pm).