Using Figure 2(a), state one physical characteristic that may be used to differentiate these two species from each other in an identification key.

With reference to Figure 2(a), state the type of biotic interaction that occurs between the imperial amazon and the red-necked amazon parrots.

Compare and contrast the realized niches of the two parrot species.

With reference to Figure 2(b), calculate the percent increase in red-necked amazon numbers between 1980 and 2012.

With reference to Figures 2(a) and 2(b), suggest two reasons why the red-necked amazon population has recovered more quickly than the imperial amazon population following Hurricane David in 1979.

chest/underbelly colour (green v. grey/blue);
head colour;
neck/throat marking (red v. grey/blue);
beak colour;
foot colour; 

Note: Do not accept only ‘colour is different'.

competition / inter-specific competition;
competition for nesting sites/food (where their distributions/habitats overlap ie altitudes 600–800 m);
resource partitioning;

both species nest in holes in trees;
both species eat fruit and nuts;
the imperial amazon feeds only in dense forest, whereas the red-necked amazon feeds in forests and plantations/red-necked amazon also eats in banana and citrus plantations;
the red-necked amazon lives between 0 and 800 m, whereas the imperial amazon lives between 600 and 1300 m/at higher elevations / both live between600 and 800 m;

Note: Must be evidence of comparison in the response: at least one compare and one contrast statement for full marks.

$\frac{\left(1250-160\right)}{160}\times 100=681\left(\%\right)/\frac{\left(1250-170\right)}{170}\times 100=635\left(\%\right)$;

Note: Accept between 635 and 681. Accept values with decimals.

Red necked amazon (RNA) more social so protection in numbers from predators, reducing mortality rates/increasing survival rates / imperial amazon (IA) lives singly so at greater risk of predation;
RNA more social so greater breeding success/greater choice of potential mates / IA has reduced mating success due to solitary behaviour/may not breed again after the loss of a mate during the hurricane / IA may die if it loses its partner;
RNA eat fruit from banana and citrus orchards/wider variety of food sources, so less competition for food / IA has a more limited food source so has greater competition for food;
RNA less specialized/can adapt to a number of different habitats so less affected by hurricane damage to the forest;
IA being outcompeted for nesting sites by the RNA;
time taken for rainforest to recover after hurricane means delay in recovery of IA / humans replant orchards so food source for RNA recovers more quickly;
initial population of RNA was higher in 1980;

This question was answered well by the majority of candidates. A few responses were too vague for credit, for example stating the birds differed in colour without reference to specific parts of the bird.

Many candidates correctly stated the interaction between the two types of parrots. However, a significant number of responses described feeding and nesting habits of the birds without stating the actual biotic interaction that was necessary for credit.

This question was well answered by many candidates. A common error was not to cover 3 different aspects for the 3 marks. For example, some candidates focused only on the altitude the birds inhabited.

Few candidates correctly calculated the percent increase.

Overall this question was well answered. Common error was to only focus on one reason rather than two.