UC Santa Cruz

The extinction of the passenger pigeon may have long-term consequences to eastern North American forest ecosystems; however, the past and ongoing consequences of the species’ extinction cannot be understood nor predicted without thorough knowledge of the species’ historic impacts. According to historic accounts, in abundance passenger pigeons generated large-scale understory and canopy disturbances. Key components needed to fully understand the impact of these disturbances remain contentious without additional data. To produce necessary data, the recent population history of the species was reconstructed using 41 complete mitochondrial genomes; limitations of diet were assessed by modeling oral gape size and the effects of digestion on seed dispersal ability was experimentally analyzed using living band-tailed pigeons, Patagioenas fasciata. Population genetic modeling found long-term stable abundance of the species over the past 20,000 years, during which time forest communities continually changed, indicating that passenger pigeons were ecologically resilient. The gape size of the passenger pigeon presented limitations to consuming the largest seeds of the Northern Red Oak and the American chestnut while exhibiting no limitations to consuming acorns of the white oak family: presenting differential selection pressures to various tree species. Passenger pigeons were not fecal dispersers of seeds, precluding mutualistic coevolution with mast bearing trees. When examining the native communities of eastern North America, disturbance dependent plant and animal species predominate, which I propose is the result of long-term impacts of large passenger pigeon flocks.