Weaver news

Weaver Wednesday 3 [251] - Range changes [14]: Southern Masked Weaver

2017-04-05 (775)

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

Southern Masked Weaver Ploceus velatus

Southern Masked Weaver, 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).

Southern Masked Weaver
Southern Masked Weaver,
figure from Birdpix

Range changes in SA

Range change summary
More 4 lists 30 lists
increases n % n %
Decrease 262 19 71 11
Tiny change 503 37 203 34
Increase 598 44 330 55
Total 1363 100 604 100
In South Africa the Southern Masked Weaver has many more grid cells with increases in reporting rate than cells showing decreases, between SABAP1 (1987-1991) and SABAP2 (2007-).

The points below match the points on the map above.

Areas with very large increases include:
1. Western Limpopo Province.
2. Most of Swaziland and southern Mpumalanga.
3. Much of the Western Cape - still increasing after arriving in the province less than a century ago.

Mixed results (increases and decreases):
4. Interior of the Northern Cape - mixed results due to poor coverage - more atlasing needed!

Areas with very large decreases:
5. Southern KwaZulu-Natal - this weaver occurs at a low density here.

Range changes elsewhere

Zimbabwe: increase in Harare due to vegetation and gardens (Brooke 1963a).