Chris - This has been an area of intense research in recent years.  It turns out that pigeons an a number of other species including bats have metal deposits in their heads.  These metal deposits, haematite, they're iron and they're magnetically sensitive.  They use the Earth's magnetic field as a kind of compass.  What they do, they know the sun rises in the east and sets in the west and so by using sunrise and sunset they are able to gain a timing.  They set their compass according to where the sun is at certain times.  That gives them their compass directions.  By changing their orientation relative to the Earth's magnetic field they are able to navigate.  They use this as a broad directional cue.  At the same time they also use visual cues because they have the hippocampus part of their brain which registers where they are in relation to their environment.  They remember visual landmarks and marry them together so they know where they're going and how they get home.

Chris - Yes, MRSA – Methicillin-Resistant Staphylococcus aureus.  This is one of the hospital superbugs that we've talked about.  It's a very resistant bacterium but there are antibiotics including one called Vancomycin which can destroy it.  It tends to colonise lots of people.  Probably about 10% of people might carry MRSA.  It's increasing in the community now.  What we're finding is that if people do get it then it can be cured by a big dose of antibiotics even if you've got it in places like the lungs.  No reason to panic too much.