The Guandu Temple (關度宮) dates back to 1661 making it one of Taiwan's oldest temples. It's location on the Danshui River is said to give the temple excellent fengshui. The temple complex is huge with long tunnels connecting the two main parts of the temple.
birds find a place to roost in the Guandu Nature Park
The Guandu Nature Park (關度自然公園) is a wetland area at the junction of the Keelung and Danshui Rivers that provides a haven for birds. If you are interested in birdwatching, then this must be one of the best places to spot birds in Taipei. 229 species of birds have been recorded at the park. It is an important stopover site for migrating birds and also a wintering and breeding ground for many species. The park is open from 9:00am to 5:00pm on weekdays and 9:00am to 6:00pm on weekends.
To get there take the MRT to Guandu Station (關度站). You can walk to the places mentioned in about fifteen minutes or take bus 小23 or a taxi. Guandu probably doesn't have enough attractions to make it worth a full day trip but you could continue on to Beitou or Danshui from here. You could also take a bus across the river to Bali and visit the Shihsanhang Museum of Archaeology (十三行博物館).