Monday, 28 March 2011
Southern Grey-headed Sparrow expanding its range
''First, a reminder about the colour coding. In green quarter degree grid cells, the reporting rate in SABAP2 is greater than in SABAP1, and in orange it is the other way round, SABAP2 has smaller reporting rate than SABAP1. Blue means that the species has expanded into this quarter degree grid cell since SABAP1. Red means the species was recorded in SABAP1, but not (yet) in SABAP2. In pink quarter degree grid cells, the species was recorded in SABAP1, but there is no SABAP2 data yet. A dot means the species was not recorded in the quarter degree grid cell in either project. Yellow means that the reporting rates are identical for both SABAP1 and 2.
Secondly, this is not a definitive analysis. It is designed to show the general pattern, and suggest the species to be looked at more carefully.
But for the Southern Grey-headed Sparrow it does not require a statistical analysis to convince us that this is a species becoming more abundant – the overwhelming abundance of green is evidence for this. And it is clearly a species moving westwards, mainly into the Western Cape.
As SABAP2 coverage becomes more comprehensive, these range-change maps become more impressive and more useful.''