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Blue gum distribution reviewed for swift parrot habitat management

Paul and Winston checking data

Paul Tilyard (UTAS) and Winston Smith (DPIPWE) check data for the E. globulus distribution map.

swift parrot by dwatts

Swift parrots rely on blue gum flowers for food during their breeding season (Photo: D Watts)

Brad Potts
School of Plant Science
University of Tasmania

Mapping of potential nesting and foraging habitat of the threatened swift parrot (Lathamus discolor) in Tasmania is being undertaken by a technical working group including representatives of the Forest Practices Authority (FPA) and Threatened Species Section of Department of Primary Industries, Parks, Water and Environment (DPIPWE).  This work is aimed at helping to manage the habitat of the swift parrot in Tasmania.  CRC researchers are contributing to this project through mapping the tree hollow habitat (subproject 4.2.5 - see r­elated article) as well as the natural range of the Tasmanian blue gum, E. globulus (subproject 4.2.7).

The swift parrot migrates into Tasmania in A­ugust for breeding. Flowering E. globulus forest is important foraging habitat during this period as the swift parrot feeds on the copious nectar and pollen produced by the large flowers of E. globulus.  While the swift parrot will also feed on other eucalypt species which flower at this time (e.g. E. ovata), the flowering resource provided by E. globulus is believed to be important for the reproductive success of the parrot. Thus, the working group is using the natural range of E. globulus as an indicator of the distribution of habitat which is important for swift parrot foraging during their breeding season.

Brad Potts and Paul Tilyard (UTAS, subproject 4.2.7) have recently finished a review of  distributional data of E. globulus in Tasmania to provide a GIS (geographical information system) layer. The review will help identify populations of E. globulus which are important for the management of the native genetic resources of the tree species itself (subproject 4.2.7).  The natural distribution of E. globulus in Tasmania had not been reviewed since the publication of the distribution maps of all the Tasmanian eucalypts in 1996 (Williams and Potts 1996). These early data were uploaded onto the Natural Values Atlas (NVA) maintained by DPIPWE, but since this period there have been a large number of new data incorporated into electronic data bases of many organisations in Tasmania. The current review integrated electronic distributional data (points and polygons) from the Natural Values Atlas and TASVEG mapping  surfaces, with electronic point data from Forestry Tasmania (FT), the Tasmanian Herbarium and UTAS.  These data were combined with new E. globulus mapping information being collected by DPIPWE and other miscellaneous observations. The screening of these data for rounding and other positional errors was greatly aided by the use of Google Earth software. Forestry, farm and ornamental plantings of E. globulus in Tasmania are relatively prolific and sometimes quite old, and non-native distributional records occur in many of the data sets examined. It is a major challenge now to separate non-native and native distributional records in such data sets and delineate the natural distribution of the species.  There have been some minor extensions of the western distributional limits and in-filling of the range compared with the distribution published in 1996, but no major geographic extensions of the native range of E. globulus have yet been confirmed.  GIS specialists from UTAS (Grant Williamson), DPIPWE (Winston Smith) and FPA (Daniel Livingston)  assisted in the production of GIS layers from the distributional data.  Mapping of E. globulus forest is continuing through a DPIPWE project and the initial surface will be updated as further information comes to hand and when potential gaps and additional records have been validated.

Biobuzz issue nine, August 2009