Bird mystery

Thanks for the feedback on the identity of the third red bird below. So far, the results are: 2 votes for house finch and one for pine grosbeak.

However, although the picture doesn't show it, the bird was absolutely tiny, and it had a complex call. The house finch that I took today, second picture below, had a very simple call.

The pine grosbeak is too big, I think.

I am thinking it is some sort of warbler. Today at the visitor's center at Saguaro national park, I saw a picture of a warbler which might have matched the mystery bird, but of course now I don't remember which it was, and there are so many warblers that I can't find it yet on the web.