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Weaver Wednesday 3 [253] - Range changes [16]: Red-billed Quelea

2017-04-19 (777)

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

Red-billed Quelea Quelea quelea

Red-billed Quelea, 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).

Red-billed Quelea
Red-billed Quelea,
figure from Birdpix

Range changes in SA

Range change summary
More 4 lists 30 lists
increases n % n %
Decrease 200 15 51 9
Tiny change 221 16 102 20
Increase 929 69 372 71
Total 1350 100 525 100
In South Africa the Red-billed Quelea 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. Free State to southern KwaZulu-Natal.
2. Western part of the Eastern Cape.
3. Most of the Western Cape - this is a range expansion in recent decades.

Mixed results (increases and decreases):
4. Limpopo Province
5. North-West Province and the Northern Cape - mixed results due to poor coverage - more atlasing needed!

6. Lesotho - occurs at low density; SABAP2 coverage too low for meaningful results.

Range changes elsewhere

Exotic populations established in foreign countries, eg Spain, Oman, Reunion: Appendix of Dyer EE, Redding DW, Blackburn TM. 2017. The global avian invasions atlas, a database of alien bird distributions worldwide. Nature Scientific Data 4 no: 170041.