1.2 Range

1.2.1 Present Range
Joseph’s map (1982) is reproduced in Figure 2 and represents both present and past sightings and reports. The information largely corresponds with recent surveys (see current sightings map www.redtail.com.au, which reveals several range extensions), although the records from Lorne and north of Horsham are unusual and were probably of stray birds.

Figure 2. Range of RTBCs (Joseph 1982)

Q.2 Establish the approximate present range by ruling a line between the outermost ‘Reliable reports’ points (solid squares), excluding Lorne and due north of Horsham.
Shade the area lightly.

Q.3 Estimate the present range*1 by ruling a 50km x 50km grid over the map and counting how many squares and % of squares are occupied by the shaded area. Add these up to achieve a total figure in km2. This area can be called the extent of occurrence, encompassing all known, inferred or projected sites.