The ivory-billed woodpecker (Campephilus principalis) was among the largest woodpeckers in the world, a striking black-and-white bird with a pale bill and, in males, a flaming red crest. Roughly half a meter long with a wingspan approaching 80 centimeters, it cut an unmistakable figure, and the awed exclamations it reportedly drew from those who saw it gave rise to its nickname, the Lord God Bird. Two subspecies are recognized: the mainland form of the southeastern United States and a separate, somewhat smaller subspecies in Cuba.
The bird was a specialist of vast, mature bottomland hardwood forest and dense southern swampland, where it foraged for wood-boring beetle larvae by stripping bark from recently dead and dying trees. That way of life demanded enormous tracts of old-growth forest, far more land per pair than most birds require, which made the species acutely vulnerable to the industrial logging that consumed the old forests of the American South.
The last widely accepted United States records come from the Singer Tract in northeastern Louisiana in the mid-1940s, as the last great stand of old-growth there was being cut. After that, the ivory-billed woodpecker entered a long and unresolved twilight: decades of tantalizing but unconfirmed reports, and a high-profile claimed rediscovery in Arkansas in the mid-2000s that remains contested.
Unlike the golden toad or the heath hen, the ivory-billed woodpecker has no agreed endpoint. As of the mid-2020s its status is genuinely disputed: a proposal to declare it extinct was advanced and then withdrawn pending further review, and the question of whether any birds survive in the southern swamps remains open.
The Xerces blue (Glaucopsyche xerces, Boisduval, 1852) was a small gossamer-winged butterfly of the family Lycaenidae, endemic to a narrow band of coastal sand-dune scrub on the northern San Francisco Peninsula. Its entire known world was a few square kilometers of stabilized dune in what are now the Sunset District and the Lobos Creek and Presidio areas of San Francisco. Males carried a shimmering lilac-blue wash across the upper wings; females were browner and more heavily bordered in black. By most accounts it is the first American butterfly, and one of the first insects of any kind in the United States, known to have been driven to extinction by urban development.
Like many lycaenids, the Xerces blue was bound tightly to a small set of partners. Its caterpillars fed on native legumes of the dune, principally deerweed (Acmispon glaber) and lupines, and the larvae appear to have engaged in a mutualism with native ants, which tended them in exchange for sugary secretions. This web of dependence on a specific plant community, a specific soil, and specific insect partners made the species exquisitely vulnerable to any disturbance of its habitat.
That habitat sat directly in the path of a growing city. Through the 1920s, 1930s, and early 1940s, San Francisco’s western dunes were graded, paved, planted, and built over. The host plants thinned, the dune community fragmented, and introduced Argentine ants are thought to have displaced the native ants on which the larvae depended. The last colonies retreated to the protected ground of the Presidio.
The Xerces blue was last seen there in the early 1940s, with sources citing 1941 or 1943. No living individual has been recorded since. The butterfly survives only as pinned specimens in museum drawers, as the namesake of a major conservation organization, and, since 2021, as a sequenced genome confirming that what was lost was a full and distinct species.