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Breeding
Raising a mohua family
A banded mohua leaves a typical nest in a beech tree (Photo: Michael Eckstadt)
The Nest
Mohua nest in holes of mature or rotting trees high in the forest canopy. Their favoured nesting trees are usually beech, especially large, old red beech (Nothofagus fusca) trees. Inside the tree-hole the female builds a cup-shaped nest of moss, rootlets, twigs and spiders’ webs and lines her nest with fine grass. Creating such a luxury nest is an unusual behaviour for hole-nesting birds, but perhaps a wise one, considering the female will now call it home for the next 20 days!
  
Photo of a typical nesting tree (left); mohua entered in the top of the dead stump (middle). Spot the incubating female in this nest (right). (Photo: J. van der Wetering) The Eggs
The first clutch of eggs will be laid by the female any time from early October to late January. In areas where there is good habitat pairs will be able to produce two clutches of eggs and raise two sets of offspring in the one summer. However today, most pairs probably lay just one clutch per year. The female can lay anywhere between one to five eggs, but three eggs is the usual clutch size. Mohua eggs are a faintly freckled pale reddish brown in colour and measure 23.5 mm long x 18 mm wide.
Incubation
The female alone incubates the eggs for about twenty days and broods the young chicks after they hatch. During these twenty days on the nest the only time the female will leave the nest is to be fed at a nearby tree by her male (read the courtship feeding story). She is very vulnerable to predation by rats or stoats while incubating - a major reason why male skewed populations occur in high predator areas.
Courtship Feeding – a description from a conservation ranger
In the mohua world incubation is entirely a female role that requires sitting on the nest for up to 20 days! But thankfully the males aren’t entirely selfish, as conservation ranger Jason van der Wetering explains:
“During the incubation phase male mohua spend most of their time travelling their territory, singing loudly and finding the odd insect to munch. Meanwhile the female, stuck in the nest cavity incubating the eggs, manages to escape once every 30 – 60 minutes for a quick feed from her mate. When she leaves the nest the female will fly to a nearby tree and call loudly. (Well actually, they yell their little heads off!). If the male is a good husband, he will stop his own singing and fly straight over to her. She will start to feed frantically, all the time fluttering her wings and making little begging twitters. The female emits many excited little buzzy shrieks in appreciation for her food and as a courtship feeding ritual that helps to strengthen the bond between the pair.”
Van der Wetering also recalls that “during the 10 – 30 minutes that the female is off the nest the male will try and feed her as many grubs as he can find, although some of the younger males are a bit slack, so the female will also try and eat whatever grubs she can find. After feeding the pair returns to the nest, the female has a quick preen and shake before heading back to incubate, and the male will fly off to resume his singing post until the next feeding round”.
A mohua fledgling on the ground having just flown from the nest and landed amongst the moss and beech tree leaves (Photo: J. van der Wetering)
For the first 5-6 days after hatching the chicks are fed regurgitated (pre-mashed) insects by their parents. As the hungry little chicks get older a range of whole insects, grubs and caterpillars are brought to the nest by the parents and any nest-helpers (often last year’s offspring). It takes around 22 days from hatching before the chicks are big and strong enough for their first flight. After fledging the nest the chicks continue to beg for food and get fed right through their first winter by their parents and helpers. The following summer these chicks will stay with their parents to become the next nest-helpers, assisting their parents to raise their younger siblings.
Through the branches you can see a long-tailed cuckoo chick being fed on the nest by a hard-working rather confused mohua parent. Compare the size difference of mother and adopted-child! (Photo: Broekema)
The hard work of incubation and raising the young is left up to the mohua (or browncreeper) nest-minders who work hard to keep enough food up to the hungry cuckoo chick. The original eggs or chicks are kicked out of the nest by the cuckoo as it quickly outgrows the size of its adopted parents. As mohua populations decline, parasitism of mohua nests by long-tailed cuckoo won’t be helping the mohua populations to recover. And if mohua were to disappear from our forests what impact would this have on the long-tailed cuckoo?
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