I'm struggling to convince myself either way! Whilst totally agreeing that colours can look very different in different lights I have not been able to come up with an image of Summer Tanager on the internet that comes close to this in terms of "brownness". Neither can I find a Piha with such a chunky bill. Here is another photo of the same bird - not sure it adds anything though.
Not to go off the subject too much but did you all know that the Summer Tanager is no longer considered to be in the Tanager Family but in the Cardinal Family? As per Wikipedia.
I've also posted the first bird on a facebook id group. Opinion there was that it is a Rufous Piha so am bumping the thread for further thoughts on this one.
Cheers
Simon