Confidence: It might be this.
Notes: To add to the confusion, I have saved the image and enhanced it a little. I see a grey back, a clear black crown with paler cheeks and throat. I do not see an eyestripe or rusty vent, and I don't think the tail or back colour are correct for Nuthatch. I agree with David, though, that there may not be a solid ID for this from the pic.