Question 1: Explain Merit

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.

Explain how a courtship strategy such as singing or flight displays can be both an advantage and a disadvantage for the male hihi, and the advantage of group nesting and of defending a territory only in the mating season.

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 The describe answer said a strong display gets a male chosen. Why is that an advantage?
Singing loudly for weeks and flying in displays takes energy, so only a strong, healthy male can do it well. Females that choose him get a fitter father for their chicks, his alleles are passed on, and his chicks are more likely to survive. Courtship also confirms the right species, so no energy is wasted on a mating that would give no viable chicks.
2 Why is it also a disadvantage?
The energy spent displaying is not available for feeding or for raising chicks. Loud song and bright flights make him easier for predators such as cats to find, and a male killed or injured in a display is out of the gene pool or cannot mate.
3 Why is group nesting an advantage?
More adults at one nest can defend the area and bring food to the chicks, so more chicks survive.
4 Why defend a territory only in the mating season?
Defence protects the food and the young when they are most vulnerable, raising survival; outside the mating season it would waste energy and risk injury for nothing.

Answer Courtship is an advantage because displaying takes energy, so only a fit male can sing and fly well; females choosing him give their chicks a fitter father, so his alleles are passed on and the chicks survive better, and courtship confirms the right species, so no breeding effort is wasted. It is a disadvantage because that energy cannot go into feeding or chick-rearing, the noise and colour draw predators such as cats, and a male killed or injured in display is lost from the gene pool or cannot mate. Group nesting puts more adults at the nest to defend it and feed the chicks, so more survive. Defending a territory only in the mating season protects food and young when they are most vulnerable, without wasting energy or risking injury the rest of the year.

What the marker wanted

Achieved The describe points: hierarchy, predation, territory, group nesting, courtship’s advantage and disadvantage, and female choice.
Merit Explains: WHY courtship gives an advantage (fitter males chosen, so the young survive and alleles are passed on); WHY it has disadvantages (predation, injury, energy taken from feeding and breeding); the advantage of group nesting; and a benefit of holding a territory only while breeding. Three make M6.

One answer, N0 to E8. Merit points sit above the Achieved ones: two give M5, three M6.

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

Common mistake

Stating an advantage and a disadvantage of courtship without saying WHY each is one. NZQA’s 2022 report says this is what kept answers at Achieved.

How did it go?

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