Importance of eucalypts in exploitation of urban parks by Rainbow and Musk Lorikeets

Abstract

The abundance and distribution of Rainbow (Trichoglossus haematodus) and Musk (Glossopsitta concinna) Lorikeets in Melbourne have increased markedly in recent years. We studied the feeding ecology of the two species, and their interspecific aggressive interactions, in some parks in Melbourne in spring and summer to determine how availability of food might affect the success of this urban proliferation. The diets of both species were dominated by nectar or pollen (the two were not distinguished in this study) from 5–6 species of eucalypts. Feeding on native plants not indigenous to the Melbourne region accounted for 61% and 74% of feeding records of Rainbow and Musk Lorikeets respectively. Both lorikeets foraged mainly in the tree canopy (99% of records), mostly perching upright or hanging to reach their food. Nectar and pollen were readily available through spring and summer because five important eucalypt food-plant species flowered constantly and several other food-plant species flowered for a substantial proportion of the time. There was little use of lorikeet food resources by other species of bird, and lorikeets were only involved in 3.5 interspecific aggressive encounters at feeding sites per observation week. The feeding ecology of the lorikeets in spring—summer was broadly similar to that reported for Melbourne in winter and for non-urban habitats in northern and eastern Australia. Abundant nectar and pollen from ornamental eucalypts planted in the twentieth century and the apparently low level of competitive interactions with other bird species for these resources have probably been important in facilitating the recent increase in abundance and distribution of both lorikeets in Melbourne.