In 1909, Charles published a series of 18 postcards produced by Chester A. Reed. They featured oil drawings. All original drawings are still owned by the Reed family.
I used pictures of the originals in this Photo Gallery, except for 6 drawings: Goldfinch. Hummingbird, Scarlet Tanager, Blue Jay, Blackburnian Wabler and Baltimore Oriole. I used postcards for this slideshow.
The originals are on display in the Reed family home in a frame similar to the one below.
You can consult the slideshow of the presentation of 18 color postcards.