It could have been a juvenile cardinal missing head feathers. The siblings sometimes pluck each others feathers out. And the bill or beak wouldn't have turned the bright red color that males get when they mature, the females have a very pale peachy colored beak.
The pigment of their skin is also black to a dark pasty grey, visible when the feathers arent' completely formed or are missing.
I found a link with pictures: check it out because only you know what you saw.
http://www.whatbird.com/browse/objs/All/birds_na_147/110/Color/2066/Red link:
If you live in the general NW US, or Canada, then it was probably the Gray Jay. If it was shorter than 10", basically anywhere in the US, then it could have been the White-breasted Nuthatch.
Male House Finch
The seagull is one.
cardinal
Sometimes cardinals because I have a bird that is my font yard every morning and it has a red head and a gray body!
Brown bird with very red beak in MA is a female Cardinal
Downey woodpecker
The Gray African Red Tail.
love bird
Female Cardinal
The answer is a Western Kingbird.
Pyrrhuloxia: Large cardinal-like finch with conspicuous red-tipped gray crest, gray head, back, upperparts, red-washed face, breast, and pale gray underparts. Dark gray wings with red edges on primaries. Tail is red. Thick yellow bill. Eats insects, larvae, seeds, fruits and berries.
Red head and black body bird
a bird
If it is a grey bird with a red "cap" it could be a Sandhill Crane
Northern Flicker.