Aquatic bird and Gallinule

Aquatic bird noun - Wading and swimming and diving birds of either fresh or salt water.

Gallinule and aquatic bird are semantically related. In some cases you can replace term "Gallinule" with "Aquatic bird", this terms are similar.

Gallinule noun - Any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens.

Aquatic bird and gallinule are semantically related. You can use "Aquatic bird" instead a noun "Gallinule".