The effect of moonlight intensity and moon phase on feeding patterns of common brushtail possums

Abstract

Feeding patterns of common brushtail possums (Trichosurus vulpecula, Kerr, 1792) were measured for 19 nights over a three-month period in forest/farmland habitat at Prices Valley, Banks Peninsula, New Zealand. The purpose of the study was to determine whether habitat choice, bait consumption rate and duration of feeding bouts were influenced by changes in moonlight intensity.

It was predicted that possum feeding activity would decrease during bright periods in response to a perceived increase in predator risk. In previous studies, various species of small mammal have been found to markedly reduce their use of open areas during periods of bright moonlight.

Feeding behaviour of possums was recorded at two bait stations using an infrared trail monitor, electronic scales, laptop computer, and time-lapse video equipment. Activity at the two stations on a forest/farmland 'edge' and in a 'forest' habitat was related to corresponding measurements of moonlight intensity, moon phase, temperature and rainfall. Activity observations were restricted to full and new moon phases.

Bait consumption at the forest-edge bait station was on average higher than bait consumption at the forest bait station. Bait consumption increased at both stations during dark nights. This effect was most pronounced at the forest bait station, where consumption increased by 33 percent during new-moon periods.

Bait consumption at the bush edge increased by only 13 percent over new- moon phases and was treated as a non-significant trend. Moonlight intensity also affected possum temporal feeding activity at both bait stations with the peaks in nightly bait consumption increasing during new moon phases. Feeding activity was not influenced by changes in light intensity resulting from shifts in cloud cover.

It is concluded that possum spatial and temporal feeding activity at bait stations is influenced by moon phase to an extent that may have important implications for the timing of future possum control operations.