Page 538 - Atlas Sea Birds Ver1

The above 16 sites may be grouped into seven regions
that provided both suitable breeding habitat and nearby
feeding grounds: Ilha dos Tigres, Swakopmund to Walvis
Bay, Orange River Estuary, the region between Velddrif
saltworks and WCNP (grouped because of a likelihood
that Caspian Terns moved breeding sites in the Berg River
Estuary and Langebaan Lagoon, Crawford et al. 1994),
Cape Agulhas vicinity, estuaries and islands in Algoa Bay,
and Lake St Lucia. The Berg River Estuary – Langebaan
Lagoon region included three other islands in WCNP
(Malgas, Marcus, and Jutten) and Vondeling Island Nature
Reserve, where Caspian Terns also bred.
In inland southern Africa, the last known record of
breeding at Vaal Dam was of four pairs in 1974 (Cooper
et al. 1992). Caspian Terns continued to utilise Kalkfontein
Dam and occurred sporadically at Barberspan (Marnewick
et al. 2015). On 31 January 2015, 106 Caspian Terns were
counted at Barberspan, but no breeding was recorded
(Coordinated Waterbird Counts https://cwac.birdmap.
africa/cards_individual.php?card=504768).Caspian
Terns were reported to breed at an island at Gariep Dam
(Marnewick et al. 2015). Twenty-six pairs bred at Sua Pan
A pair of Caspian Terns at Velddrif saltworks, 2012 (photo RJM in 1985 (Cooper et al. 1992). Caspian Terns have visited
Crawford) several other inland waterbodies. For example, up to
54 birds were seen at Hardap Dam in southern Namibia,
(1980), Randall et al. (1981), Cooper et al. (1992), Williams although breeding was not reported there (Simmons 2015).
et al. (2004), Dyer (2007), Kemper et al. (2007), Crawford In South Africa, amongst other places, Caspian Terns have
et al. (2009), Bowker and Downs (2012), AEWA (2015), been seen at Krugersdrift, Vanderkloof, Bloemhof, and
Ortmann et al. (2015), Simmons (2015), and relevant Darlington (in Greater Addo Elephant National Park) dams.
breeding site chapters in this volume. When multiple counts
were obtained at a site in a given year, the maximum was Population trend and conservation status
used. When a range was given, as for Lake St Lucia in
1972 (Berruti 1980), the mid-point was used. ‘√’ signifies When maxima recorded at coastal colonies were summed
that breeding occurred at a site but the numbers were not for each of the five most recent decades, the resulting
ascertained; ‘?’ that breeding may have taken place. totals were 833 pairs in the 1970s, 415 pairs in the 1980s,
The maximum number of birds recorded or estimated 393 pairs in the 1990s, 699 pairs in the 2000s, and 596
to have bred varied from one pair at each of 12 sites to pairs in the 2010s (Table 2). These trends were influenced
c. 750 pairs (500–1,000 pairs in Berruti 1980) at Lake by numbers observed at Lake St Lucia and the coverage
St Lucia (Table 2). At Lake St Lucia, 23 other annual of colonies. The number used for Lake St Lucia in 1972
estimates were between 100 and 400 pairs (Fox et al. was 750 pairs, which was the mid-point of the range
2024). No site other than Lake St Lucia held more than of 500–1,000 pairs reported by Berruti (1980). Had the
100 pairs and only five others had maxima > 50 pairs: Ilha minimum value of the range (500 pairs) been used instead,
dos Tigres 88 pairs, Velddrif Saltworks 85 pairs, Swartkops the sum of maxima at coastal colonies in the 1970s would
River Saltpans 58 pairs, Lower Berg River Saltworks have been 583 pairs. Ten coastal sites were counted
55 pairs, and Mile 4 Saltworks at Swakopmund 51 pairs. in the 1970s, 13 in the 1980s, seven in the 1990s, 17 in
Walvis Bay Saltworks had 48 pairs in 2004 and Stag Island the 2000s, and 30 in the 2010s, so that coverage of sites
in Algoa Bay 35–50 pairs in 1936. Lake St Lucia, on South was more complete in the 21 than 20 centuries and
th
st
Africa’s east coast has a surface area of 225–417 km most complete in the 2010s. No counts were known for
2
depending on its water level (Fox et al. 2024). Ilha dos colonies in Angola or Namibia in the 1990s. It should be
Tigres is a large, sandy island off southern Angola that noted that, although Caspian Terns often show fidelity to
forms the western border of Baia dos Tigres towards the sites, because they sometimes change their breeding sites
north of the Benguela upwelling ecosystem (Morais 2024). (e.g. Cooper et al. 1992, Crawford et al. 1994, Bowker
Five other substantive colonies were at coastal saltworks, and Downs 2012, Martin and Whittington 2024), totals of
two in central Namibia, two in western, and one in southern decadal maxima at sites may overestimate abundance. A
South Africa, the latter and Stag Island being at the east reduction in the period over which maxima are summed
of the Benguela upwelling ecosystem. Other sites to have may reduce overestimation, but it may also result in under
housed 10 or more pairs were the Orange River Estuary estimation if fewer colonies are visited in the period. From
(Cooper et al. 1992), three islands in Langebaan Lagoon 2018–2022, when information was available for 31 of
(Meeuw, Schaapen, and Caspian) that are in the West the coastal colonies, the sum of maxima at colonies was
Coast National Park (WCNP), three sites in the vicinity of 319 pairs (Table 2). The sum of the most recent estimate
Cape Agulhas (Dyer Island, Die Dam, and the Heuningnes made at each of the 37 colonies used to assess trends in
River Mouth at De Mond) and Coega Saltworks at Algoa the coastal population was 397 pairs (Table 2). However,
Bay. in certain instances the most recent counts were outdated.

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