Blue Tit

Cyanistes caeruleus

Appearance:
Bright blue crown
White forehead and cheeks
Dark blue line passing through eyes and encircling the white cheeks to the chin
Blue nape, wings and tail
White bar on wings
Yellowish-green back
Yellow underparts with a dark line down the abdomen
Black bill
Bluish-grey legs

I spent today at the London Wetlands. As their website says, it is an urban oasis and definitely worth a visit. One of the many birds I saw there was this handsome Blue Tit.  It was checking out the interior of a little birdhouse.  I initially thought that it was feeding little ones inside, but apparently it's too early for that.  According to the internet, late May is the time for Blue Tit chicks to hatch.
  

juvenile

Learn more about the Blue Tit.