Degree: Master of Science in Environmental Studies

Title: Monitoring comparative spatial and temporal variation in the land-birds of Vago-Savura Forest Reserve, a native lowland rainforest in south east Viti Levu, Fiji.

Principal supervisors: Dr. Dick Watling and Dr. Craig Morley

Status: Completed

Abstract:

Birds are an important indicator species and part of Fiji’s Natural Heritage. As most bird surveys conducted in Fiji to date were qualitative, very little is known about the ecology, population abundance and seasonality of many of Fiji’s land birds. The current study included a three month preliminary survey followed by 12 months of bird surveys using the Variable Circular Plot (VCP) survey technique along a fixed transect within the Vago-Savura Forest Reserve. The purpose of these surveys was to identify a pattern of seasonality in the detected abundance of the native land birds in the Vago-Savura Forest Reserve. To answer this, the study was divided into four main parts: a preliminary study, museum study, bird survey, and tree phenology study.

The preliminary study, conducted over a three month period, involved weekly counts at 15 stations. Bird surveys in the morning recorded more bird species and overall abundance compared to afternoon surveys. A species-time curve was constructed from the bird count data, and it was determined that the optimal time to record all the common bird species required at a station was eight minutes.

Museum specimens of Fiji’s native land birds were examined for primary wing moult. Of the 187 specimens examined, 67 showed evidence of primary wing moult. Only 49 specimens were properly labelled, including the date of collection. Moulting was commonly observed in specimens collected in the months of November to February.

Weekly bird surveys were conducted at 10 stations for a period of one year from January 2005 to December 2005. A total of 35 species was recorded from the study site, and the phenology of 26 species of native birds was recorded and graphed. A total of 3780 detections were made, of xiii which 87% were detected audibly and only 13% visually. Bird detectability was highest from June to November and the lowest from January to May, indicating seasonality in bird activity. High detectability coincided with peak breeding months and low detectability with the peak moulting period of Fiji’s native land birds.

Ten 25 m x 25 m plots were set up at each station, and the flowering and fruiting phenology of all the trees (>10 cm diameter at breast height) present in the plots were recorded monthly during the bird surveys. A total of 714 trees comprising 87 species were monitored during the 12- month period. A small percentage of trees flowered (188) and 267 trees bore fruit during the study. Flowering was more commonly observed from April to October and a peak in the number of fruiting trees recorded from September to December. The peak in flowering coincided with the late dry season and the peak in fruiting with the early wet season.