Historically, their colonies were an important source of guano, the rich natural fertiliser formed from seabird excrement in arid areas. Throughout most of the 20th century, people were stationed on the gannets’ breeding islands to protect the birds and their precious guano, which was scraped up after each breeding season. As a result, we have a good record of how gannet numbers have changed since the first census was conducted in the mid-1950s.
Over this period, Cape Gannets have bred at only six islands: Mercury, Ichaboe and Possession off southern Namibia, and Lambert’s Bay, Malgas, and Algoa Bay’s Bird Island off southern Africa. In the 1950s, there were some 260 000 pairs of Cape Gannets, 80 per cent of which bred in Namibia. Today there are barely 130 000 pairs, 95 per cent of which breed in South Africa. As a result, the species is listed as globally Endangered and as Critically Endangered in Namibia.
The dramatic decline of the Namibian colonies resulted from the collapse of that country’s sardine population due to overfishing in the 1960s and 1970s. Dwindling fish stocks off the South African west coast over the past two decades have seen gannet numbers decreasing at both Lambert’s Bay and Malgas Island, and the colony on Bird Island in Algoa Bay now supports almost three-quarters of all Cape Gannets in the world. This is the only stable population – all five colonies off the west coast continue to decrease.
Denne historien er fra January/February 2022-utgaven av African Birdlife.
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Denne historien er fra January/February 2022-utgaven av African Birdlife.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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EXPLORING NEW HORIZONS
Keith Barnes, co-author of the new Field Guide to Birds of Greater Southern Africa, chats about the long-neglected birding regions just north of the Kunene and Zambezi, getting back to watching birds and the vulture that changed his life.
footloose IN FYNBOS
The Walker Bay Diversity Trail is a leisurely hike with a multitude of flowers, feathers and flavours along the way.
Living forwards
How photographing birds helps me face adversity
CAPE crusade
The Cape Bird Club/City of Cape Town Birding Big Year Challenge
water & WINGS
WATER IS LIFE. As wildlife photographer Greg du Toit knows better than most.
winter wanderer
as summer becomes a memory in the south, the skies are a little quieter as the migrants have returned to the warming north. But one bird endemic to the southern African region takes its own little winter journey.
when perfect isn't enough
Egg signatures and forgeries in the cuckoo-drongo arms race
Southern SIGHTINGS
The late summer period naturally started quietening down after the midsummer excitement, but there were still some classy rarities on offer for birders all over the subregion. As always, none of the records included here have been adjudicated by any of the subregion's Rarities Committees.
flood impact on wetland birds
One of the features of a warming planet is increasingly erratic rainfall; years of drought followed by devastating floods. Fortunately, many waterbirds are pre-adapted to cope with such extremes, especially in southern Africa where they have evolved to exploit episodic rainfall events in semi-arid and arid regions. But how do waterbirds respond to floods in areas where rainfall - and access to water - is more predictable? Peter Ryan explores the consequences of recent floods on the birds of the Western Cape's Olifants River valley.
a star is born
It’s every producer’s dream to plan a wildlife television series and pick the right characters before filming.
