Decline that led to wirebird breeding failures

Wirebird on its nest in grass

Ground-nesting wirebirds are vulnerable to cats and rats (picture: Shelco)

When the experts from Shelco went to look round the site of their proposed eco-resort on St Helena, they were greeted by one of the locals.

A rat.

It was evidence – not really needed – that it’s not only people that find Broad Bottom one of the most attractive spots on St Helena. Rattus Norvegicus and Rattus Rattus have found it increasingly congenial too.

And wirebird eggs and chicks are favoured delicacies in the rodent diet. Not one wirebird chick survived the last breeding season at Broad Bottom – one of the prime nesting sites for St Helena’s unique but critically endangered bird species.

Shelco’s plans for a hotel, lodges and “eco golf course” seek to reverse the landscape changes that have led rats to increase, and wirebird numbers to fall.

The developer’s environmental consultant, Dr Keith Duff, says rats thrive because of a lack of controls, and the spread of scrub and flax, which harbour predators:

“There is some periodic control of rats at Broad Bottom Farm by St Helena Government pest control operatives, using poison baits, but this is only done in response to requests from Solomons on public health grounds.

“Government action to control rats does not extend to doing this to protect wirebirds.

“Stands of flax, and scrub, provide nesting areas for rats, so a successful predator control programme needs to be done in parallel with a scrub clearance and management programme.”

The other big problem for the ground-nesting wirebirds, he says, is loss of suitable habitat.

Wirebirds like to nest on ground that’s not too steep, where the grass is short  – apparently so they can keep an eye out for predators.  Shelco has suggested digging “shelves” into the hillside at Broad Bottom to make the land more conducive to nesting.

Flax and pine range across a spur of land, with a small patch of grass centre of shot

Flax, pine and grass have invaded Sebastopol, by Broad Bottom (picture: Shelco)

In the past, there were plenty of sheep and cattle to graze the pastures, but not any more. Solomon and Company keeps a small herd of cattle at Broad Bottom, but no sheep.

Cattle only trim the grass to 75 millimetres, which Dr Duff says is not enough for the wirebirds to keep their lookout. So Shelco proposes grazing by sheep as well, to bring the grass down to a favourable height.

It should be said that Dr Fiona Burns of the RSPB, who has researched wirebirds on the island, does not share his view about the need for grazing by sheep.

The Shelco adviser goes on to say that because cattle are moved around the site, “only a small part of the Broad Bottom wirebird census area is ever in ideal condition for wirebirds at any one time.” He says:

“Large areas of the Sebastopol grazing unit have been over-run by extensive and thick stands of scrub, primarily gorse, white weed and pine. The same is true, to a lesser extent, of parts of Ding Dong Gut.

“This seems to haveresulted from reduced grazing levels in recent years, and has led to loss of both pasture and wirebird habitat. If remedial action is not taken soon it is likely that these areas will be permanently lost to wirebirds, and to grazing.

“Scrub also shows signs of expanding within many of the other grazing compartments.

“The only way to overcome this major problem is through a major scrub clearance exercise.”

Dr Duff told St Helena Online:  “The key point which we are trying to address at Broad Bottom is to reverse the bad situation which has developed.

Artist's impression of the hotel from the south

An 88-room hotel and tourist lodges are planned at Broad Bottom (picture: Shelco)

“I am not implying, or seeking to imply, any criticism of anyone in my report.  The reality is that the current situation at Broad Bottom is not good for wirebirds.”

Dr Burns takes a sympathetic view of the circumstances behind the habitat loss.

“Across the whole island, grazing animals has not been profitable, so farms have declined in recent years and in several areas that has led to habitat becoming less suitable, not just at this location. Land has become overgrown, but that is part of a whole-island issue.

“There is no obligation at present for a landowner to maintain land in a way that is beneficial to wirebirds. In the future, new protection might have some implications.”

St Helena Government is establishing Important Wirebird Areas, including Broad Bottom. Legal protection could come into effect by 2013.

The RSPB is also doing more research on cats and rats, and the way their populations impact on each other (if you reduce the number of cats because they attack wirebirds, will rats become more of a problem?).

“Hopefully that will be able to inform more sensible management,” says Fiona Burns. “At the moment the government of St Helena mostly targets rodent control around places where people live, but we would hope in the future they might be able to take on some level of control for the sake of wirebirds.”

  • On most parts of St Helena, cats are the main threat to wirebirds. Dr Fiona Burns set up cameras to monitor attacks on nests. Sixty five per cent of raids caught on film were by cats. Bizarrely, a sheep was also filmed taking an egg, and one chick on the point of hatching was killed by ants.

SEE ALSO:
RSPB objects to Shelco resort over wirebird doubts (with more links)

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