Teesmouth Bird Club

Having just entered a sighting of such an individual, I wondered if what I had seen was merely nothing more than a young male bird which was yet to be hormonally pumped up to display adult colouring. Seeing a male Blackbird in the autumn without a yellow bill would be to expected and not wothy of comment, but this late in the season when the birds are preparing for early breeding, makes one think.
The internet lists a range of sub species of Blackbird but nothing such as adult males with dark bills.
Any ideas chaps?

I'm sure I read somewhere that continental Blackbirds that migrate here for winter along with other winter thrushes usually have black as opposed to yellow bills, though I can't now find the reference. We've got a few in the garden at present.

In the sighting entry, you say the primaries were brown - so it's presumably a 1st winter bird.  I've had one such bird with a dark bill in the garden within the last couple of weeks.  The acquisition of a yellow bill can be quite late - BWP describes the bill of northern populations as "....remaining dark into winter, becoming marked with yellow usually in the course of late winter and early spring (individually variable)....".  The only difference mentioned is that southern races get the yellow considerably earlier (even in the females)

Eric

there has been a male blackbird with all black billl and brown primaries present in my girlfriends parents garden for the last few weeks in hartlepool

Thanks Eric, I shall settle for your explaination.