Can a tag on the prey's leg harm a peregrine falcon if eaten?

Question

I saw a bird (the mother) swallow the birdring of another bird it was eating on live camera (while feeding its chicks) link (the site is in Polish) and I am wondering whether:

• Can it actually cause harm or is it designed not to? (Researchers might have taken into account that the smaller birds could get eaten, when designing the tag)

Answer 1

My research indicates that the answer is no.

Chicago Exotics Animal Hospital says:

lead, zinc, copper, mercury and iron cause metal toxicosis if ingested by birds.........................CAGES should be made of safe metal with non-toxic paint,............... Stainless steel is the safest metal.

According to the US Geological Survey:

There are three commonly used type of bird bands. The lock-on type is used for birds with very strong beaks such as hawks and owls and

The band is made of relatively soft aluminum and can be removed by the bander, but not by the bird.

                                 and

Rivet bands are made of harder metal than the lock-on band (but not stainless steel) and are used on eagles.

The most commonly used band is the butt-end-band, and the source does not say what metal is used for this band ... but its picture looks like aluminum. Bird bands come in many sizes, from hummingbird-sized to trumpeter swan sized

ParrotForums.com says:

Aluminum isn't toxic to birds. The only aluminum product that should be watched for is aluminum foil as it contains tin (toxic to birds).