I was in San Diego 5/7-14. The zoo offered several interesting opportunities but not as many avian as I would have liked. The birds for the most part were caged or in large screened aviaries making photos difficult. Some of the multi-specie aviaries offered good opportunities. The hummingbird house had several beautiful Tanagers but only 4 hummers of which 3 were Costas (2 female/1 male) and a very nice Sparkling Violetear. Some outdoor open areas had good avian possibilities. The absolute best was the outdoor Flamingo pond which was loaded with mud nests and birds sitting on an egg. There was also a Crested Screamer in there sitting on a nest with 3 eggs and 2 Scarlet Ibises. You are right on top of these birds. Several other avian opportunities were available. If you want to shoot the Pandas get there real early as the line gets very long. Only 2 were on display, one sleeping and one sitting and eating bamboo. No problem on the Koalas though pretty sedentary. The zoo admission is $40 for 1 day and $76 for 2 days. It is in Balboa Park which also has numerous other opportunities especially if you want to shoot orchids in the botanical building. Almost all of this is adjacent to the zoo. I wanted to go tho the Safari Park but it is 35 miles from the zoo and without a car was 6 hours round trip on public transportation. Skip the Chula Vista nature park accessible by trolley and free shuttle bus as construction had the only trail closed. You might consider taking the trolley to the Tijuana Estuary (on the US side) probably about a 30-40 minute ride. I did not have a chance to get there If you are not going to have a car get a multi day trolley/bus pass from the vending machines at a trolley stop (1 day $5, 2 days $9, 3 days $12 and 4 days $15). One day passes are also available on buses from the driver. No one checks your pass on the trolley but the fine if you get caught without a ticket can be several hundred. We also road bikes in Balboa Park, on Coronado Island and on the Embarcadero even all the way to Old Town and back.