Nuttall had a broad expertise in all aspects of natural history, and through his influence, Gambel developed an affinity for botany, mineralogy, and ornithology.
They returned to Philadelphia in April 1839 and then quickly set off again for a field trip to New Jersey to study and collect pre-Cambrian limestone minerals.
In March 1841, at the age of eighteen, Gambel set off on his own for California to collect plants and other specimens for Nuttall.
Gambel reached Santa Fe in June and spent the next couple months collecting plants.
The new bird species he collected included Gambel's quail (Callipepla gambelii), mountain chickadee (Parus gambeli) and Nuttall's woodpecker (Picoides nuttallii).
By midsummer, Gambel was out of money and became a clerk on the US Navy ship Cyane, commanded by Thomas ap Catesby Jones.
On April 5, 1849, Gambel and an acquaintance, Isaac Wistar, left for the difficult overland journey to California.
In Independence, Missouri, they formed a larger party led by Wistar and made good progress westward.
However, Gambel grew tired of the group's fast pace and joined a slower-moving ox-train led by Captain Boone of Kentucky.
In December, Gambel reached Rose's Bar, a gold mining camp on the Yuba River.
He was buried at the base of a giant ponderosa pine, but the entire site was soon washed away by hydraulic mining.