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Salt in bird baths and leftovers could kill garden birds

24/02/2010 11:36:52
birds/2010 jan/rspb_birdbath

Juvenile blackbird in birdbath. Ray Kennedy (

Salty food potentially lethal to birds
February 2010. A pinch of salt might make many of our favourite dishes that bit tastier, but it could kill some garden birds. The RSPB is urging people not to use salt as a de-icer in bird baths, as temperatures are set to plummet below freezing again.

The RSPB suggests placing a small floating item, such as a twig or a cork, into bird baths when they are first filled. This will keep the water moving, preventing it freezing solid. Alternatively, filling it with tepid water each morning will prevent it freezing for as long as possible.

Salt is toxic to gardens birds
Salt is toxic to gardens birds. Their bodies are unable to process it, and it affects their nervous systems. Birds become very thirsty and dehydrated when they ingest salt, meaning they would drink more, potentially exacerbating the problem. They would also suffer kidney dysfunction. Some small birds are not much bigger than one of our own kidneys, which we use to process salt, and they will overdose very quickly.

Salty water bad for bird feathers
Although most dangerous when ingested, salty water is not good for birds externally either. It could damage their feathers, meaning they are not in peak condition during the cold weather and into the breeding season. Even if they don't drink it, they could still ingest it as they preen.

No chemicals
The RSPB doesn't recommend any chemicals for unfreezing bird baths, and de-icers must also never be used. Birds may be drinking water from salty puddles as iced-over paths and roads that have been treated start to melt, so fresh water that we provide could also help reduce any harmful effects from that.

Crisps, salted nuts and salty kitchen scraps - bad
The charity also asks that we avoid feeding salty kitchen scraps to birds. Salted crisps and peanuts, processed cheese and leftover frozen meals are all likely to contain levels of salt dangerous to birds. Even if these items are soaked, they would likely still contain dangerous levels of salt.

Good leftovers
More suitable leftovers include grated mild cheese, porridge oats, coked rice, unsalted bacon, cooked potatoes and pastry.

Richard James, RSPB Wildlife Adviser says: "It's understandable that people think salt is a suitable way of keeping bird baths unfrozen, as we see it sprinkled over roads and paths all the time. But it is an extremely dangerous to garden birds, and must be avoided at all costs. Making sure bird baths don't freeze over can be difficult in cold weather and unfortunately it's a case of checking it and refilling it as often as possible. You could try putting a small floating item like a twig or even a ping pong ball in the water or filling it with slightly warm water which would prolong the freezing. Thankfully here in the UK we love our garden birds and many people will do all they can to make sure they have a supply of water at all times. It may fill us with dread but dipping into a cold bath is important for garden birds at this time of year, for both drinking and keeping feathers in good condition."

For more information on feeding garden birds in winter click here.  

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