Vertical and seasonal distribution of airborne invertebrates in mixed lowland forest of the Orongorongo Valley, Wellington, New Zealand

Abstract

Aerial traps were used to continuously sample the airborne fauna at various heights in mixed lowland forest for about 2 years. Insects were the dominant constituents of catches. Flies (75.7%) and beetles (5.3%) dominated catches in traps at 3, 12, and 22 m above ground, but there were significantly fewer beetles at 22 m than at other heights. Small insects predominated in the sample, having possibly been carried upwards in convection currents. Generally, more invertebrates were caught from spring to autumn than in winter. The aerial trap catches of beetles, flies, and wasps were positively correlated with the numbers caught in emergence traps. The vertical distribution of insects is compared with the catches of some forest insectivorous birds in tiered mist nets in the same study area. About as many invertebrates were caught in broadleaf-podocarp forest as were caught in hard beech forest. However, if flies are excluded, significantly more invertebrates were caught in the broadleaf-podocarp forest.

Keywords:

• aerial traps
• invertebrate fauna
• forest birds
• vertical distribution
• forest canopy
• broadleaf-podocarp
• Nothofagus truncata
• Orongorongo Valley