Table 2. Putative hypotheses related to the frequency of accidental parrot releases.

Hypothesis	Prediction	Supporting evidence
Propagule pressure	Cheaper species should have a greater chance of being released because they are more abundant in captivity, and because they are more likely to be kept under looser security measures.	[19,47,48]
Life history traits	Larger bodied and longer lived species should be less likely to escape because these species are usually more economically and emotionally valued and therefore more carefully kept.	[49–51]
Native status	Australian native parrots should be more likely to escape than non-natives, because natives are more abundant in domestic captivity, and because native species are less economically valued than non-natives.	[52,53]
Behavioural traits	Docile species should be less likely to escape because owners are more likely to become strongly bonded and care more about their welfare.	[54–56]