Wednesday, July 8, 2009

Love and War Among the Hawaiian Goose

Love is definitely in the air among the nene this month. Love – and war… Hormones are changing.

We have already had a sample of the noisy territorial disputes to come. A note in my journal for last year mentions that on June 28th many new pairs of geese and small groups arrived in the valley within hours of each other, and began exploring. I was curious to see if there was any noticeable change this year to the peaceful predictability that has settled amongst the different mini-flocks. Early every morning the regulars arrive from the Crater Hill direction and settle in their familiar groups and favorite places, returning the same way before dark.

Morning of June 26: New nene arriving to explore the Waipa valley in preparation for the fall/winter nesting season.

This year on the 26th we saw exactly the same phenomenon. Dozens of new nene began arriving and spread out exploring the wider area, still in their own small summer flocks, made up of established pairs with grown young and single birds – and some of the males were already focusing on their females. A few began “shoulder honking”, following the female’s every step and honking with their necks outstretched close to her ear. This coincides with a new vigor in their chases of other males that they may have tolerated a month ago.

On the 28th June this year Oma’o Dad was mindlessly placing nesting material around himself as his mate slept beside him. When they left, there was a neat arc of dry mango leaves, roots and stems where he had sat.

These are early days; the wars have yet to build in volume and intensity, as chases become fights for the best areas. This bonding and assertiveness lasts a long time. The first nests here were not established until September last year, and this end of June burst of activity seems to herald the beginning. Peaceful tolerance has returned only temporarily.

Where the Waipa joins Hanalei Bay. Geese can often be seen from here as they head back towards Crater Hill in the evening.

In earlier posts I talked about a male who abandoned his mate while she was on the nest, leaving with a female we called Nahe. He and his mate had been a devoted pair for several years, and since their number bands are only five numbers apart, this suggests they may have known each other as goslings.

He was very strong - the beta male - and could hold his territory from all other male birds except the alpha bird of this area.. After every battle he would return victorious to “present” himself, with chest expanded, beak pointing skywards on elongated neck, and stand proudly before his mate. He accompanied her day after day as she searched different areas for a nesting site, but when she chose her place, the separation began. He sat in another place they had also both favored, calling for her.

He showed little interest in the nest she made in a mosquito - infested area, preferring an overgrown breezy spot beside the river, and it was during this time of sitting alone he formed his attachment with Nahe, a first-year bird, and mated with her.

He and Nahe behaved like a couple, but would occasionally go to stand guard together near the nest site. But when he heard the voices of the young goslings, he left Nahe and walked to the nest and gazed at them. Then he became fiercely protective, chasing everything - including Nahe - away from his family.

The upper Waipa Stream

Now he followed his first mate, who led them higher up the river valley. Nahe was abandoned. She called in anguish for two days, and then followed the family trail. When she located them, she walked at a distance behind the family, never wavering even though she was courted by other males.

The Beta male cleared away any male that attempted to court her, but stayed defending his family for two months , occasionally seeking Nahe out and ”presenting“ to her as if she was his real mate. But when mate number one got up to leave with the goslings, he always joined them.

When the youngsters began their first flights, he and Nahe left together and did not return. His first mate stayed alone with the two young ones, was accepted by the alpha pair, and had a high rank within the flock, but her two young became the omega birds. Without a male to protect them, they were chased by every adult and have become thin, nervous birds. On occasion their mother defends them from another female, but never from a male.

This is unusual behavior among supposedly-monogamous nene, especially a successful nesting pair. Conrad Lorenz studied monogamous, non-migratory graylag geese for most of his life, living alongside them. He noticed the same phenomenon on only three occasions, involving just two males. He described it as an intense, passionate attraction - as if the geese were smitten with each other.

Bernd Heinrich, in his study of migratory Canada Geese, thought the timing of the arrival at their nesting site after migration played a crucial part in pair-bonding. Possession of the nest site seemed to be critical with them. But the nene do not migrate, they travel together to slightly different locations for nesting. It is interesting that the nest was a pivotal factor in this story, their separation first occurred over nesting preference.

The passion between Nahe and the male was obvious, and is still there, as well as her grief when he left. They were by the river yesterday. He was an eager male, honking beside her face, edging her towards his chosen nesting area of last year with shoulder pushes.

June sunset over Hanalei Bay

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