State of the Bay Report 2010-Final - Anchor Environmental

Anchor Environmental
No breeding pairs have been counted on Malgas Island since the 1920’s. A low number of
breeding pairs were counted on Marcus and Jutten Islands intermittently between 1973 and 1987
when they stopped breeding there and colonized Schaapen, Meeuw and Vondeling islands
(Crawford et al. 1994). In 1995, 130 breeding pairs were present on Schaapen Island but this
population declined to 45 pairs by 2003 with only two pairs were seen in 2004, after which breeding
stopped (Figure 11.8). Vondeling Island had just a few breeding pairs of birds (between two and
nine) that used the island intermittently between 1987 and 1997 with no recorded breeding since.
Meeuw Island is currently the only island with breeding birds on. There are yearly counts available
from all 6 islands since 1989 and in that time the total population has halved, from 202 pairs to 92
pairs, indicating that conditions in Saldanha Bay have deteriorated for these birds.
Number of breeding pairs
250
200
150
100
50
0
1973
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
State of the Bay 2010: Saldanha Bay and Langebaan Lagoon 244
Year
Total
Marcus
Jutten
Schaapen
Vondeling
Meeuw
Figure 11.8. Trends in breeding population of White-breasted Cormorants at Marcus, Jutten, Schaapen,
Vondeling and Meeuw islands in Saldanha Bay (Data source: Rob Crawford, Oceans & Coasts,
Department of Environmental Affairs).
Human disturbance poses a serious threat at breeding sites. These cormorants are more
susceptible to disturbance than the other marine cormorants, and leave their nests for extended
periods if disturbed, exposing eggs and chicks to Kelp Gull predation. Other mortality factors include
Avian Cholera, oil pollution, discarded fishing line and hunting inland (du Toit 2004). Due to
Schaapen Islands’ close proximity to the town of Langebaan with high boating, kite-boarding and
other recreational use of the area, it is possible that the decline in White-breasted cormorants is due
at least in part to increased levels of human disturbance.
Crowned Cormorants, Phalacrocorax coronatus, are endemic to Namibia and South Africa
occurring between the Bird Rock Guano Platform in southern Namibia and Quoin Rock, South Africa.
It is listed as Near Threatened on the IUCN’s Red Data List due to its small and range restricted
population, making it very vulnerable to threats at their breeding colonies (Birdlife International
2011). This species is highly susceptible to human disturbance and predation by fur seals,
particularly of fledglings. Crowned Cormorants generally occur within 10 km from the coastline and
occasionally in estuaries and sewage works up to 500 m from the sea. They feed on slow-moving