Wednesday, May 20, 2009

Endangered Birds, Nesting In the Rushes

My drawing of alae'ula courting in the rushes

The large patch of native rushes across the river from us has held many surprises. The rush is a beautiful native plant, in full flower just now. Dragonflies and damselflies, emerging from the aquatic phase of their lives, climb the smooth stems to dry their new wings. There are particular days when there are so many hatchings of an individual species, the air is full of their rainbowed wings.

One farmers' market this month stands out vividly, as it coincided with a hatching of a giant blue dragonfly, the largest I’ve ever seen - must have a six -inch wingspan. They flew between shoppers, dozens at a time; a small clearing in the centre contained hundreds of them. They hovered and flew so skillfully in the crowded area - but no-one gave them a second look!

One year the endangered Alae’ula nested within the rushes close by, (endemic gallinules, also called mudhens, or moorhens), and this year a pair of koloa (endangered native ducks) are there, much more often than usual.

The ducks mated at the river's edge, and though the mating was short, the larger gathering of accompanying males took hours to depart. It was an extremely wet day, heavy fast rain, splashing as it hit the surface of the stream. You could see the water level rising by the minute as rain-flow from the hills reaches here very quickly; the type of weather my grandparents called “lovely weather for ducks”.

The mating bird is obscuring the female - the koloa on the left is the male-in-waiting...

Koloa began flying in, landing in twos and threes on the water The female bird was caught in the water by the male, and half-carried him on her back as she swam to the edge of the rushes. There were several other males in attendance; one remained very close throughout but did not try to intervene, apart from briefly climbing on the males' back to make a pile of three!

More ducks were gathered in the stream, one to two feet away, paddling on the spot and turning in an excited manner. There was no fighting, just waiting. Afterwards most of them bathed, with much splashing and preening, and stayed long after the event. They were not nearly as shy as normal.

It was hours before the last onlooker took flight, and at least one bird still sat in the rushes. They might both have been there, as she seemed to retreat further in. The darkening day and continuous rain made it impossible to identify the color of the beak. Beak color is a useful guide to their sex. Adult males often have an olive-green bill, whereas the females' are in tones of warm brown, difficult colors to discern in the shadow of rushes.

In Hawaiian Birdlife, (1972) Andrew Berger describes a nuptial flight of two or three birds climbing to around a hundred feet and chasing in small circles, the favored male always closest to the female, a second suitor sometimes diving on the pair, and small chases ensuing. We see variations of this often in the valley, and the same exuberance they display in the air seemed present in the water. The three remaining males that took no part in the event remained close in a little triad for a long time too.

Mother with six of the seven ducklings (the seventh is hidden in the rushes)

Now, weeks later, the mother has appeared with her young ducklings still with their egg tooth. She appears at first glance to be a single bird. The rushes are perfect for the babies, who all vanish at times into the narrow channels, slowly reappearing again. There are seven of them. Their first days will be hard. The introduced bullfrogs are large enough to take one of these tiny birds; owls, egrets and herons are also predatory, especially when they are small and there is the ever-present threat of feral cats and dogs.

As an endangered species, they are facing many challenges - but their biggest threat comes from introduced mallards. A much larger duck, mallard males are very aggressive, and interbreed with the tiny native Koloa. A koloa male stays with his family - but not a mallard.

In just a few short years the island of Oahu lost its tiny native koloa to mallard hybrids, and Kauai now has the same problem. It is still possible to see koloa, especially in Hanalei - but where will we be in two years? Hanalei on Kauai is the only place left to easily see pure Koloa ducks

Below are two links for those interested.

Alae'ula: Dad feeding baby

Near the bay, the Waipa Foundation has restored an old fish pond, a small spur off the main river. They have planted large areas of native wetland species there and a pair of Alae'ula (mudhen) used it this year for their nesting-place. The nest was well hidden in the thickly planted marginal vegetation, and the tall rushes offered shelter for their tiny young.

These birds are a special favorite of mine, they show each other much affection by preening, and the care shown to their chicks is more marked than a lot of waterbirds.

They have only one chick left now, half-grown, and even though it can feed itself, both parents are diligently feeding it. The rest of the clutch will have been lost to some of the same predators that attack koloa.

We watched a heron leaving the wetland, and as it flew low past the rushes where the family were, the male alau’ula ran towards it, leaping in to the air to peck at the much larger bird as it passed.

It is especially nice to watch them in this habitat, full of native plants. One plant grows in and out of the water, just high enough to almost obscure the young, but growing from the mud means they can search the soft ground in relative safety. This is a very endangered bird; some scientists estimate there may be only a few hundred left, but almost certainly less than a thousand - nearly all of them on Kauai.

The Hawaiians are fond of it too. It holds a special place in their mythology, giving to the people the gift of fire. All alae‘ula belong to Hina, the moon goddess, and they appear in many shape-shifting stories.

Dad preening Mom, with the baby between them


Koloa Hybridization Paper
This short report has a graph on page 3 showing how quickly Oahu lost their Koloa.
In 1990 there was less than one mallard hybrid present in every wetland studied. In just two years, by 1992, the koloa were virtually lost, every wetland contained more hybrids than koloa, and by 1994 the ratio was 8 hybrids to one pure koloa.

Endangered species newsletter
Open Kia Moku Vol1 issue 2 2006
An interesting newsletter on ways we can help.