Today, lots of bird seed bought in shops/online is in good condition for birds and other wildlife; however some seed on sale is not dust free. The dust is just lots of tiny broken bits of debris which accumulate and lay on the seed giving a powdery appearance – this has been proven to damage birds’ respiratory systems. The dust is really damaging and difficult to remove so this causes long term effects. See https://www.thespruce.com/no-waste-bird-foods-386548, http://www.fao.org/docrep/008/y5831e/y5831e05.htm and https://www.bto.org/volunteer-surveys/gbw/gardens-wildlife/garden-birds/feeding for more information about these issues.
There are many places where dust free seed can be bought like the RSPB and other specialist wildlife suppliers such as Haith’s. In my own experience most pet shops tend to not have dust free seed. To help raise awareness that dust free seed is very important to the health of birds, Haith’s (https://www.haiths.com/bird-food/) asked me if I would be prepared to write an article on its benefits. To help me do this they sent me samples of both types of seed for a comparison.
On inspecting both packets of seed it was clear that dust free seed had minimal residue at the bottom of packet. In contrast the non-cleaned seed a significant quantity of dust residue which was clearly visible at the bottom of the pack. Haith’s in my opinion is one of the best places to buy seed as they ‘superclean’ their seed to ensure the birds stay healthy. By cleaning their seed they are able to remove the dust which makes the seed in much better condition and healthier for birds!
To test whether birds prefer dust free seed I used two identical ‘My favourites’ feeders which were sited in their usual position in my garden. As the seed with dust is harmful over long term use I only ran the test for 120 mins; exactly halfway through the test I swapped the feeders round. During the experiment I recorded the birds visiting each feeder.
The results showed out of 26 birds (siskins, blue tits, coal tits, great tits, robins and chaffinches) visiting the feeders, 71% favoured the super-cleaned seed. The fact that there was no dust present on the seeds would have been beneficial to the birds for the reasons outlined above. I do think they realized after a few tries that the feeder with uncleaned seed had an unpleasant taste because of the dust. Once they realized this, they stuck with the ‘supercleaned’ seed from (https://haiths.com/bird-food/).