Page 40 - Atlas Sea Birds Ver1

A A
2,50 2 500
2,19
2,00 1,98 1,68 2 000
1,37 1,38
1,50 1,29 1,32 1 500
1,17
1,00 1 000 R = 0,29
2
0,50 0,19 0,19 500
0,07 0,11

B 0,25 0,27 300 B
0,25 240 R = 0,0876
Number of nests / km 0,15 0,17 0,30 0,17 0,10 0,08 0,07 0,07 Number of females 180
2
0,20
120
0,10
60
0,03
0,05
0,000,00
125 000
C 100 000 C
125 117 107
100 102 75 000 2
70 67 50 000 R = 0,7165
75 66 62 63 60 62
54 54 25 000
50
2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21
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2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 Average Nesting season

Nesting season Figure 5. Trends in numbers of female turtles nesting along the
Angolan coast for (A) Leatherback, (B) Green and (C) Olive Ridley
turtles, 2010/11–2020/21. Maxima (blue), minima (red), estimated
Figure 4. Average number of nests per kilometer for the Angola as described in the text, and the best-fitting linear regressions
coast, for (A) Leatherback, (B) Green and (C) Olive Ridley turtles, (with R values) for maxima are shown
2
2010/11–2020/21 and overall
Leatherback Turtle (Dermochelys coriacea) Chaverri 1999), an average of c. 850 females nested
annually on the coast of Angola (range 426–1,277 nests/
From 2003–2021, the Palmeirinhas region had the high- year) during 2010–2021, with a minimum of 426 (assuming
est density of Leatherback Turtle nests (2.3 per km, females laid three nests per season) and a maximum of
Figure 3). The weighted average of densities found at all 1,277 nesting females. However, in this period there was a
localities sampled in Angola in this period was 1.3 nests decrease in the population that nested along the coast of
per km (Figure 4). There was a fluctuating decrease of Angola (Figure 5).
the overall number of nests between 2010/11 and 2020/21
(Figure 4). Although the fit was poor, it should be borne Green Turtle (Chelonia mydas)
in mind that female Leatherback Turtles abstain from
breeding at intervals of 2 or 3 years (Girondot and Fretey Green Turtles had a patchy breeding distribution along the
1996, Chevalier and Girondot 1998, Chacón-Chaverri coast of Angola (Figure 2) and at monitored localities were
1999). most frequently observed nesting in the southern region,
Based on the average number of nests recorded at the with fewer records from the north and almost none in the
different sampling sites of the Kitabanga project, the dis- central part of Angola (Figure 3). Based on an analysis of
tribution area, that females can lay 1 to 12 nests in the the average densities of nests found at different latitudes
same season (Fretey and Girondot 1989, Tucker and Fraz- along the coast, it was estimated that the annual density
er 1991, Reina et al. 2002) and abstinences from breed- was around one nest for every 10 km of beach (Figure 4).
ing that may occur at intervals of 2 or 3 years (Girondot Over time, oscillations in numbers nesting with periods of
and Fretey 1996, Chevalier and Girondot 1998, Chacón- 2–3 years were noted, which may have been associated

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