Step-by-step explanation:
On island A,
Parrots with Dd were released therefore these will mate with each other and will produce:
 Dd x Dd
  D d 
 D DD Dd
  d  Dd dd
Therefore, 25% DD, 50% Dd and 25% dd genotype parrot offspings will be produced.
On island B, parrots with DD and dd were released, therefore they will mate and will produce,
 DD x dd
1.  D D
  d   Dd Dd
  d  Dd Dd
2. DD x DD
  D D 
 D  DD DD
 D  DD DD
3. dd x dd
 d d
 d  dd dd
 d  dd dd
This shows that there is a possibility on island A where 25% DD, 50% Dd and 25% dd genotype parrot offsprings will be produced whereas on island B, chances are almost equal as all three genotype parrot offsprings can be produced but the percentage could vary.