Table 1.
Detailed information on the waterbird variable traits and their descriptions. Categorical variables (C) and quantitative variables (Q).
| Categories | Type | Trait | Description | Source |
|---|---|---|---|---|
| Categories | C | Families | Divided into four groups according to their families and habits | b and c |
| C | Residence | Four groups: summer visitor, winter visitor, passage, and resident | c and d | |
| C | Breeding | Two groups: breeding and non-breeding | b, c, and d | |
| C | Diet | Six groups: herbivore, insectivore, carnivore, piscivore, benthivore, and omnivore | b | |
| C | Nest sites | Five groups: bare ground, cliff, float, grass or shrub, and tree | a and b | |
| Body | Q | Mass (g) | a and b | |
| Q | Size (mm) | a and b | ||
| Flying ability | Q | Wingspan (mm) | a and b | |
| Q | Wing length (mm) | a and b | ||
| Q | Tail length (mm) | b | ||
| Foraging ability | Q | Bill length (mm) | b | |
| Q | Tarsus length (mm) | b | ||
| Reproduction | Q | Incubation (day) | a and b | |
| Q | Clutch (number) | a and b | ||
| Q | Nest size (mm) | a and b |
a: Birds of the World, www.birdsoftheworld.org/, accessed on 12 September 2019; b: Avifauna of China, Zhengjie Zhao, 2001; c: A Checklist on the Classification and Distribution of the Birds of China, Guangmei Zheng, 2017; and d: Avian Monitoring Report in Liaohe Estuary Natural Reserve, 2010–2020.