If you are a bird lover i suggest a visit to the free aviary located in hong kong park. I had visited victoria peak earlier in the day and heard the birds chirping but could not visibly see them. The aviary is setup with feeding stations near the paths to attract the birds so those with only phone cameras with enough patience can get good photos. The most colorful birds there were the lory

Get down to Airport (GTC) Bus Terminus.
Take Bus A43 to Sheung Shui Railway Station, Price: 30,9 HKD. Transpottime: ~1 houer.
Take MTR East Railline to Lok Ma Chau, (Futian Port), Price: 23 HKD. (one station) time: ~15 min.
Short Walk to Checkpoint Hong Kong/China. Time for Inspection: ca 30-90 minute. Then walk to Short Walk to Futian Checkpoint. Metro 4, Longhua Line. Ticket: 4 RMB to Shenzhen North Station. 9 stations. Time: ca 20 min.
Take e.g. G1004, take you to Wuhan on 4 houer 11 minute, (1171 km) The train stops only in Guangzhou South and Changsha South. Price: 540 RMB.