Grazing no problem for totara

1. Native regrowth

Some native tree species are able to regenerate even in the presence of grazing mammals.

Rotorua-based researchers David Bergin and Mark Kimberley monitored totara seedlings for 10 years on a Northland farm. Despite cattle grazing, the totara was able to regenerate on steeper hill slopes.

Bergin and Kimberly suggested allowing totara to regenerate on pastoral hill country could be an option for re-establishing woody vegetation on otherwise marginal hill land.

2. No link between vaccine and blood clots

A large-scale Danish study has found no link between Gardasil, a vaccine for human papillomavirus (HPV), and blood clots.

Preliminary data had suggested a possible link between the vaccine and a certain type of blood clot. But a study of more than 1.6 million Danish women, 500,000 of whom had been vaccinated, found no increased risk of blood clots after HPV vaccination.

Most cases of cervical cancer are caused by HPV infection. In New Zealand, Gardasil is publicly funded for women under 20.

3. Prehistoric Tonga a social hub

Prehistoric Tonga was a Pacific hub for socialising, archaeologists say. Analysis of stone tools uncovered in Tonga showed almost two-thirds of the tools in the past 1000 years were long-distance imports from Fiji, Samoa and the Society Islands. The Australian researchers suggested the stone artefacts were likely to have been an important source of political capital for Tongan elites.

4. Giant, extinct bird

An ancient bird was twice the size of today's largest flying bird but still managed to fly. Pelagornis sandersi, which lived 25 to 28 million years ago, had a wingspan of about 6.4 metres, twice that of the royal albatross that nests on Taiaroa Head in Otago.

United States scientists recreated the bird's dimensions from a fossil skull, wing and leg bones. It was previously thought that wingspans greater than 5m would prevent flight but models suggest the prehistoric giant was capable of gliding - although to get airborne the big bird probably needed to run downhill into wind gusts, much like a hang-glider.

The fossil was found in 1983 during construction of a new terminal at Charleston International Airport, in South Carolina.

5. A whale of an engineer

Despite being relatively rare, whales can greatly influence their marine habitats. US researchers have collated years of data on whales to show how the marine mammals are "ecosystem engineers", driving nutrient cycling and carbon storage in oceans. Baleen and sperm whales recycle nutrients in the ocean by feeding at great depths then releasing faecal matter near the surface, where it promotes plankton growth. Even after they die, their bodies become habitat for species that exist only on whale carcasses.

As whale populations recover from hunting, the researchers suggest these ecosystem effects could lead to higher productivity in commercial fisheries.

The Press