Have I ever brought the Morguefile to your attention? It's a site where people can upload photographs for artists to use as a reference without expecting credit or payment.
It's a easy to use site, tons of photos of purt near everything, and it's free! You'll see a row of buttons near the top. Make sure Morguefile is selected, because the site is linked to other sites where you can buy photos for use. WARNING: This site is addictive. Did I mention the tons of photos? I could get lost for hours, and am tempted to download everything!
I found the reference photo for this fella, who has I painted in watercolor on Kilimanjaro Natural, Cold Press.