Plastic has been recorded in the stomachs of about half of all the world’s seabird species and, given the ubiquitous nature of microfibres in the world’s oceans, it is likely that all species have been exposed to some ingested plastic.
So what? Seabirds often consume indigestible items, which they either regurgitate or excrete. The seabirds such as petrels and phalaropes that accumulate large plastic loads in their stomachs seldom regurgitate pellets and only excrete very small items. Yet these species evolved in an environment where they often eat pumice, seeds and other natural debris floating at sea. Like ingested plastics, pumice and seeds (and indigestible prey remains such as squid beaks) are gradually worn down in the stomach and excreted. So is eating plastic a problem?
Ingested plastic is thought to have three main impacts on seabirds. Firstly, it might block or damage the digestive tract, leading to injury or death. The blockage is a significant issue for turtles, but there are only a few records of seabirds with their guts obstructed by ingested plastic items – many fewer than are entangled in marine litter. In terms of internal injury, seabirds often swallow sharp objects such as spiny fish and crustaceans. Gull regurgitations frequently contain pieces of glass and metal, which are more likely to injure than plastic.
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.
