Weaver news

Weaver Wednesday 3 [241] - Range changes [4]: Sociable Weaver

2017-01-25 (763)


gravit8 Weaver Wednesday 3: range changes in S Africa (species text)

Scaly-feathered Finch Sporopipes squamifrons

map
Scaly-feathered Finch, Range-change map between SABAP1 (1987-1991) and SABAP2 (2007-current).
Red, orange and yellow = cells with very large, large, and small relative decreases
Blue, dark green and light green = cells with very large, large and small relative increases.
Cells = quarter-degree grid cells; Only cells with at least 4 checklists in both SABAP1&2 shown. All cells had this species recorded in SABAP1 or in SABAP2 or in both (more about interpretation at Biodiversity Observations 7.62: 1-13).

Scaly-feathered Finch
Scaly-feathered Finch,
figure from Birdpix

Range changes in SA

Range change summary
More 4 lists 30 lists
increases n % n %
Decrease 206 30 68 41
Tiny change 141 21 38 23
Increase 337 50 61 36
Total 684 100 167 100
In South Africa the Scaly-feathered Finch has more grid cells with increases in reporting rate than cells showing decreases, between SABAP1 (1987-1991) and SABAP2 (2007-), although this is reversed when using 30 checklists for the analysis. The points below match the points on the map above.

Areas with very large increases include:
1. range expansion towards Pafuri (KNP), and breeding
2. range increases around Burgersfort
3. Northern Cape and western Free State show large or very large increases
4. Western parts of the Eastern Cape areas show large or very large increases

Large decreases appear to have occurred:
5. In Gauteng it has a very low reporting rate, probably due to decreases in size of suitable habitat patches
6. Large or very large decreases appear to have occurred over large areas of northern South Africa, probably related to habitat changes.

Range changes elsewhere

Angola: range extends further than mapped in (Fry 2004a) (in prep.). Zimbabwe: range increasing around Bulawayo (Dean 1963a).