Wilson's Warbler

Description:

Male has a black cap, olive upper body and brilliant lemon yellow lower body. The female and juvenile do not have the black cap, but have the yellow underparts.

Habitat:

Along streams and in moist thickets in woodlands, although this individual was sighted in a courtyard outside a the main building of the Arizona Sonara Desert Museum near Tucson, Arizona

Notes:

In some of the references I used to identify this bird, it was described as not fearing humans. This was certainly true of this little male as I photographed it.