Geospiza fortis
The Medium Ground Finch, *Geospiza fortis*, is an iconic passerine, a cornerstone of evolutionary biology. Averaging 12-14 cm in length and weighing 19-29 grams, it is characterized by its stocky build and, most notably, its robust, conical beak, intermediate in size among the ground finches. Adult males are predominantly sooty black, while females and juveniles exhibit dull, streaky brown plumage with paler underparts and often a faintly streaked throat. These finches belong to the family Th...
This species primarily inhabits the arid lowlands and dry scrub of the Galapagos Islands, preferring open woodlands and areas with sparse vegetation. They are typically found from sea level up to mid-elevations, adapting to the varying dryness of the volcanic archipelago.
The diet of the Medium Ground Finch consists predominantly of seeds, particularly those of *Tribulus cistoides*, but also includes a significant proportion of insects, especially during the breeding season. They are primarily ground foragers, using their robust beaks to crack open hard seeds.
Geospiza fortis is a diurnal species, spending its days foraging on the ground and roosting communally in shrubs or trees at night, especially outside the breeding season. Their foraging strategy primarily involves gleaning seeds and insects from the ground, often using their powerful beaks to cr...
The Medium Ground Finch is endemic to the Galápagos Islands, an archipelago belonging to Ecuador. It is widely distributed across many of the central and southern islands, including Santa Cruz, Daphne Major, Floreana, Isabela, Santiago, Fernandina, Pinzón, and Rabida. This species is a year-round...
Least Concern
- The Medium Ground Finch's beak size and shape can change rapidly between generations, a prime example of natural selection in action observed by Peter and Rosemary Grant on Daphne Major. - Its adaptability to different seed sizes and hardness, particularly after droughts, directly affects its s...