New Zealand gloxinia or Rhabdothamnus solandri is a gangly forest shrub, which grows in the shade to about 2m high and produces an orange tubular flower.
The researchers wanted to observe the impact on New Zealand gloxinia of these disappearing bird populations and so compared the situation on the mainland with that of three nearby island bird sanctuaries where the birds remain abundant.
They say the disappearance of two birds - the bellbird and stitchbird - from the upper North Island of the country has lead to a slow decline in common plants, including the forest shrub New Zealand gloxinia.