Rare NZ grasshopper loses ground to cows

ENDANGERED: The Brachaspis robustus grasshopper is found only in the Mackenzie district.
ENDANGERED: The Brachaspis robustus grasshopper is found only in the Mackenzie district.

An endangered grasshopper found only in the Mackenzie Basin is under threat from dairying.

Changes to the natural habitat of the Brachaspis robustus grasshopper have caused the population to decrease, according to Department of Conservation invertebrate ecologist Warren Chinn.

The grasshopper is is not found anywhere else in the world.

The last count of the species was carried out in 2010. Mr Chinn estimates there would be roughly 2500 to 3000 grasshoppers in the lower Mackenzie Basin at monitored sites.

The species is on the same endangered level as birds like the kaka and kea.

Mr Chinn said it was a "big battle" to raise awareness because the grasshopper lacked the "cute and fluffy" factor of birds.

The grasshopper is short, stocky and flightless, 20 to 40 millimetres long, with a slate grey colour, which Mr Chinn said was key to its survival.

The colour helped the robustus blend in with the surrounding pebbles, camouflaging it from predators, and the dark colour helped the cold-blooded creature absorb heat from the sun.

The grasshoppers inhabit rocky areas near riverbeds and lay their eggs in silty soils.

Mr Chinn said their habitat was becoming severely reduced because of the spread of pasture seed and the hydroelectric-power system.

However, he believed the biggest disruption was dairy conversions. "It is an ecological disaster. I don't care how much money it brings in, it is a national disgrace."

Mr Chinn said the robustus was an icon of the Mackenzie district and people needed to know the value of having rare species in their backyard.

"It's like having a rare book in a library of species. We're reducing the amount of rare editions and increasing the proportion of glib magazines."

DOC's main goal was to prevent the loss of Brachaspis robustus population. One of the long-term plans was to establish a grasshopper reserve.

The Timaru Herald