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Rangatira Island in the Chathams

Alison Ballance with a Chatham snipe that landed on her backpack, and view of South East Island from the shore platform (images: A. Ballance)

In part one of a new series about the natural world of the Chatham Islands, Alison Ballance heads to remote Rangatira, or South East Island. Rangatira is a nature reserve, and although it is small - just 219 hectares in area, with a highest point of 224 metres - it is the stronghold for some of New Zealand's rarest wildlife including New Zealand shore plovers, Chatham snipe and Chatham petrels. Black robin were translocated there in the 1980s, and it now has a population of 120-130 birds, with another 30 or so living on nearby Mangere Island. Department of Conservation ranger Abi Liddy gives Alison an introductory tour of the island and some of its special residents.

Unloading equipment on South East Island's shore platform, Abi Liddy weighing a bird, and island sign.

View of Pitt Island from South East Island summit, forest interior with seabird burrows honeycombing the forest floor, and view of The Clears (images: A. Ballance)

Using Sound to Measure Density

Under the guidance of supervisor Clive Davies (right) at Massey University's School of Engineering and Advanced Technology, PhD student Emile Webster (left) is developing a technique to measure volume without using water.

With a Helmholtz resonator and specifically designed computer software, the volume of items such as kiwi fruit can be measured. This in turn can be used to calculate the density of the fruit, which gives an indication of ripeness.

The technique can also be used to measure other types of fruit and vegetables, mineral samples, and in some instances powders.

Cicadas

There may be as many as 50-60 species of cicada in New Zealand, found from the dunes to the alpine zone. The largest species is the chorus cicada (Amphipsalta zelandica), which has a wingspan of up to eight centimetres, while the smallest species of Maoricicada have a wingspan of less than 3 centimetres. The chorus cicada is the loudest and one of the most familiar cicadas, and its Māori name is kihikihi wawā - wawā meaning 'to roar like the sound of heavy rain'.

Cicada expert Chris Simon (right) splits her time between the University of Connecticut in the United States, and her study site in her Wellington garden, which is home to five species of cicada. Alison Ballance visits her in her garden to meet a shade-singing cicada called Kikihia scutellaris, which she refers to as the washing line cicada, and to find out about biology of our familiar noisy neighbours. Part two of this story will air next week.

There are some great online cicada references: check out Chris Simon's Cicada Central, where you can see pictures and hear audio of cicada songs; Landcare Research has a virtual identification guide; and Te Ara also has lots of interesting information.

Synaptic Connections in the Brain

(image: Centre for Brain Research)

This week (15 to 21 March) is Brain Awareness Week, and Our Changing World is back at the University of Auckland's Centre for Brain Research where Johanna Montgomery (above) is recording the signals brain cells send to each other through the synapses.

Using techniques like live cell imaging and electrophysiology, the Synaptic Function Research Group is trying to understand the mechanisms guiding the formation, maintenance, plasticity and elimination of synapses.

As Ruth Beran discovers, growing the neurons in the lab and then watching them in real time is a delicate process.

This is the second story in a two-part series on the brain. The first story ran last week on Our Changing World and took a peek inside the Human Brain Bank with University of Auckland's Maurice Curtis who is using tissue from bequeathed brains to research neurodegenerative diseases.

To find out more about events around New Zealand during Brain Awareness Week, click here.

Next Week

The Prime Minister's Future Scientist and winner of the Supreme Award in the Royal Society's 2009 Realise the Dream Competition, high performance ceramics, Chatham petrels and part two of the cicada story.