( 1.) The bird's success in driving off his rivals. ( 2. ) The size of territory the bird needs and ( 3. ) How much food is available.
Generally in Spring but it depend son lots of things.
The state bird (avian emblem) for the Northern Territory is the Wedge-tailed Eagle.
The Rose-ringed Parakeet or (Psittacula krameri) the unofficial bird of Islamabad Capital territory.
The Blood pheasant (Ithaginis cruentus) is the national bird of the disputed territory of Sikkim.
the new territory name is Nunavut
The Falco peregrinus peregrinator is the bird un officially representing the Gilgit-Baltistan Disputed territory.
The state bird of the Disputed occupied territory of Jammu and Kashmir is the Same as Azad Jammu and Kashmir.
The national bird of Guam is the koko bird
The state bird for Australian Capital Territory (ACT) is the Black Swan.
The Great hornbill (Buceros bicornis) is the so-called state bird of the disputed territory of Arunachal Pradesh, Republic of India.
Guam is a territory and as of current does not have a state bird.
The Common Raven is the provincial bird of yukon territiries.