Question 3: Describe Achieved

Practises Social behaviour & spatial behaviour

Australian chestnut-crowned babblers (Pomatostomus ruficeps) live in social groups of up to about 25, dust-bathing, preening and feeding together. They search for food as a group: insects, spiders, small amphibians, crustaceans and reptiles, and fruit and seeds. At night they crowd into one large central nest; when alarmed they huddle under thick foliage or fly up into the lower canopy, chattering loudly. Breeding runs from about July to November, with one large clutch from all the breeding pairs. The whole group builds the single nest, feeds the incubating females and defends the breeding territory, and a pair seldom tries to breed without help. There are often about 4 breeding males and as many as 12 helper-males that do not breed. Kin selection seems to matter: females will not help care for young they are not related to.

Define territory and kin selection, and describe an advantage of finding food as a group and of preening each other, why the helper-males help with the chicks, and why the unrelated females do not.

The 2024 paper, page 10 ↗ Marking schedule, page 6 ↗

Work it out

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

1 What is a territory, and what does one give the babblers?
An area with set boundaries that its owners defend against others of their species. It gives the group the food, shelter and nest site inside it.
2 What is kin selection?
Helping relatives survive and reproduce, even at a cost to yourself, because they carry many of the same alleles.
3 What does a babbler gain by looking for food in a group?
More birds searching find more food, so the adults and chicks are more likely to get enough.
4 What does preening each other do?
It removes skin and feather parasites such as ticks and lice.
5 Why do the helper-males help raise chicks, and why do the unrelated females not?
The helper-males share alleles with the chicks, which are their relatives. The unrelated females share none, so they do not help.

Answer A territory is a bounded area that its owners defend against others of their species; it gives the group the food, shelter and nest site inside it. Kin selection is helping relatives survive and reproduce, even at a cost to yourself, because they share your alleles. Searching for food in a group finds more food for adults and chicks, and preening each other removes parasites such as ticks. Helper-males help raise the chicks because they share alleles with them; unrelated females share none, so they do not help.

What the marker wanted

Achieved Defines or describes, one point each: territory; kin selection; what the territory gives the babblers; males helping because they share alleles with the chicks; one advantage of social behaviour, such as finding food together; a second, such as preening to remove parasites; unrelated females not helping because they share no alleles. Four make A4.

The schedule marks the question as one answer from N0 to E8. Achieved points count first: one or two give N1 or N2, three A3, four A4. Above that, two Merit points give M5 and three M6. In 2024 Excellence needs more than usual: TWO Excellence points give E7, three or more E8.

In our words, from NZQA’s 2024 marking schedule.

Common mistake

A loose definition of kin selection, such as “helping the group”. NZQA’s 2024 report says many candidates could not define kin selection well enough; say that the animals helped are relatives who share alleles.

How did it go?

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