My mind tends to wander on a monday morning walking into work and this morning was no different. I was thinking about rarities in back gardens of the birding and non birding public and seeing as we have Dark-eyed Junco and Two-barred Crossbill visiting gardens at the moment, I was wondering how many of these birds get missed as they turn up in areas where there are no birders or people interested enough to notice something different.
I have done a little calculation which is probably unsound both mathematically and ornithologically:
Let us say that there are 10,000 homes in Britain with a garden and good birder or an interested member of the non birding public who would report an odd bird. Let us also say that there are 5,000,000 homes with a garden that could hold birds.
Taking these two birds, that is 2 in 10,000 and scaling that to the 5,000,000 homes, we reach a number of 1000 rarities in English gardens at the moment! Obviously not true so we have to take into account that birds are mobile and visit say 10 gardens - that takes our number down to 100 rarities.
Clearly this is an overestimate of immense proportions and perhaps someone who knows something about maths might come up with a more sound and reasonable formula.
However, it shows that birds do turn up in suburban gardens and perhaps we should be checking such areas more. Loads of good birds in the past have turned up in birders gardens and it makes you wonder how many gems are tucked away right under our noses!!