This rather dark bird resembles the smaller and finer-beaked common cactus finch, but the two species do not co-inhabit any island.

[2] An ancestral relative of those grassquits arrived on the Galápagos Islands some 2–3 million years ago, and the Española cactus finch is one of the species that evolved from that ancestor.

The Española cactus finch (G. conirostris) first arrived in Daphne Major in 1981, when it was observed to be a newcomer by Peter and Rosemary Grant.

This has enabled scientists to trace changes in its genome: it originally interbred with local finches (G. fortis) but has ceased to do so in later generations.

Female and immature birds range in color from dull gray to matte black, and frequently show white edges to the feathers of their underparts.