A resident of Shenzhen in south China's Guangdong Province gave a seaside park a bad review for being too dark. But there's a good reason the lights are kept low.

Shenzhen Bay is an important stopover and wintering site for migratory birds, with nearly 100,000 birds visiting each year. Bright artificial lighting can disrupt their resting and migration patterns.

The city has replaced some waterfront streetlights with low-impact warm yellow lighting, introduced timed dimming and shutoffs, and added bird-friendly markings to glass buildings to help prevent collisions.

A new regulation, which took effect on November 5, puts the protection of mangrove wetlands and migratory birds on a stronger legal footing, requiring better planning and control of nighttime lighting around bird habitats.