Flocking to a lake made by weather in Te Hauke

Two black swans swanning around in the ephemeral wetland at Te Hauke next to State Highway 2. Photo / Paul Taylor

More recent rain and cooler temperatures should mean flocks of black swans and hundreds - if not thousands - of other waterfowl and wetland birds continue to take up residence in the shallow, temporary lake next to State Highway 2 at Te Hauke for some time yet.

The heavy rains dumped on CHB and much of the rest of the country last month by ex-Tropical Cyclones Debbie and Cook have flooded farmland just to the east of the highway, resulting in the explosion of birdlife.

Stephen Cave, Hawke's Bay Regional Council's Open Spaces manager, said the flood waters around the periphery of nearby Lake Poukawa were an example of an ephemeral wetland - a temporary wetland which only occurs seasonally after heavy rains.

"Ephemeral water, especially in farm paddocks, tends to be shallow and very productive biologically, with micro-organisms and insects proliferating, as well as worms coming to the surface. This makes ephemeral water a great source of food for wetland birds, hence the swans and waterfowl present in the flood waters at Te Hauke," he said.

Most of the birds would normally live in the surrounding landscape such as Lake Poukawa and the Pekapeka Wetlands, said Mr Cave.

"They are just much more visible in a pastoral paddock feeding, as opposed to being nestled in amongst Raupo and Willow."

Nathan Burkepile, senior Hawke's Bay officer with Fish and Game, said ephemeral wetlands were once one of the dominant wetland types in Hawke's Bay, but were now the rarest.

The Poukawa wetland historically was larger but a lot of it had been drained, he said.
However if current levels of farming in the area continued, the temporary wetland might one day become a permanent fixture, he said.

"The wetland is on peat soils and with current farming, that peat is disappearing which is lowering the land making it more prone to flooding and also the water stays on for longer periods of time.

If current farming continues, we will see this area become a permanent wetland as Lake Poukawa would be higher than the surrounding land, which may - or may not - eventually drain the lake," he said.