Question 1: Discuss Excellence

Practises Social behaviour & spatial behaviour

The stitchbird, or hihi (Notiomystis cincta), lives only in New Zealand, and now only on islands or on mainland sites it has been moved to, because of predators such as domestic cats. It breeds in an unusual way, nesting in pairs or in groups; the paper sets group nesting in bold. Hihi defend a territory in the mating season (also bold), which runs through spring and summer. Their dominance hierarchies are well known: older birds dominate younger ones, above all of their own sex, and males dominate females, except when there are chicks at the nest. From the start of the breeding season until egg laying ends, the males sing loudly, and at the nesting area they put on flight displays that show off their white and yellow colouring.

Discuss how the hihi’s behaviours work together to support its population size, evaluating how the two bold behaviours maintain the population in protected areas.

The 2022 paper, page 2 ↗ Marking schedule, page 1 ↗

Work it out

Try it on paper first. Stuck? Take one hint at a time.

1 Start with the two bold behaviours. What does each cost, and what does it gain?
Group nesting costs sharing, and some conflict over the nest, but gives more adults to watch for predators, defend the nest and feed the chicks. Territory defence costs energy and risks injury, but only in the mating season, when it protects the food and the young.
2 Do the benefits outweigh those costs, and what for the population?
Yes: more chicks survive, and they are better fed, so more young join the population each year. In protected areas, where predators are few, that maintains the hihi population or lets it grow.
3 How do the hierarchy and courtship fit in?
The hierarchy settles who gets resources without constant fighting, saving energy and injuries; males giving way to females at the nest lets chicks be fed first. Courtship lets females choose the fittest males, so the chicks are fitter as well as more numerous.
4 So how do all four work together?
Courtship gives fitter chicks, group nesting and seasonal territory defence give more of them, and the hierarchy keeps the costs of living together low. Together they mean more, fitter young survive, which maintains the population.

Answer Group nesting costs some sharing of the nest but gives more adults to watch for predators, defend the nest and feed the chicks; defending a territory costs energy and risks injury, but only in the mating season, when it protects food and young. The benefits outweigh those costs: more chicks survive, better fed, so in protected areas with few predators the population is maintained or grows. The other behaviours add to this. The hierarchy settles access to resources without constant fighting, and males give way to females at a nest with chicks, so the chicks are fed. Courtship lets females choose the fittest males, so the chicks are fitter as well as more numerous. Together, courtship gives fitter young, group nesting and seasonal territory defence give more of them, and the hierarchy keeps the costs of living together low: more, fitter young survive, which maintains the hihi population.

What the marker wanted

Achieved The describe points: hierarchy, predation, territory, group nesting, courtship’s advantage and disadvantage, female choice.
Merit Those explained: why courtship helps and why it costs, group nesting’s advantage, and the benefit of mating-season territory defence.
Excellence E7: how what the two bold behaviours gain (group nesting, and holding a territory while breeding) outweighs what they cost, keeping numbers up because more, and fitter, chicks survive. E8: a fully linked answer that brings in the hierarchy and courtship too, showing how all four behaviours together keep numbers up the same way.

One answer, N0 to E8. In 2022 Question One, E7 is the first Excellence bullet and E8 the fully linked second one.

In our words, from NZQA’s 2022 marking schedule.

Common mistake

Writing “the benefits outweigh the costs” without naming a single specific cost. NZQA’s 2022 report says many candidates did exactly that, and it held their grades down.

How did it go?

Got it moves it further out. Review brings it back tomorrow.