Legacy or colonization? Posteruption establishment of peregrine falcons (Falco peregrinus) on a volcanically active subarctic island

Abstract

How populations and communities reassemble following disturbances are affected by a number of factors, with the arrival order of founding populations often having a profound influence on later populations and community structure. Kasatochi Island is a small volcano located in the central Aleutian archipelago that erupted violently August 8, 2008, sterilizing the island of avian biodiversity. Prior to the eruption, Kasatochi was the center of abundance for breeding seabirds in the central Aleutian Islands and supported several breeding pairs of peregrine falcons (Falco peregrinus). We examined the reestablishment of peregrine falcons on Kasatochi by evaluating the genetic relatedness among legacy samples collected in 2006 to those collected posteruption and to other falcons breeding along the archipelago. No genotypes found in posteruption samples were identical to genotypes collected from pre‐eruption samples. However, genetic analyses suggest that individuals closely related to peregrine falcons occupying pre‐eruption Kasatochi returned following the eruption and successfully fledged young; thus, a genetic legacy of pre‐eruption falcons was present on posteruption Kasatochi Island. We hypothesize that the rapid reestablishment of peregrine falcons on Kasatochi was likely facilitated by behavioral characteristics of peregrine falcons breeding in the Aleutian Islands, such as year‐round residency and breeding site fidelity, the presence of an abundant food source (seabirds), and limited vegetation requirements by seabirds and falcons.

New insights into the phylogenetics and population structure of the prairie falcon (Falco mexicanus)

“…For example, panmixia indicates a putative tendency for F. mexicanus to disperse throughout its range. This may serve to recover populations locally extirpated as a result of development [ 26 ], similar to the sources-sink dynamics demonstrated for recovering peregrine falcon populations in California [ 115 , 116 ] or the recolonization of volcanic islands post-eruption [ 117 ]. Lastly, our sequencing of the prairie falcon genome provides the raw data for subsequent studies of repetitive elements, chromosomal organization and many other research avenues.…”

Past volcanic activity predisposes an endemic threatened seabird to negative anthropogenic impacts

“…Moreover, this eruptive period was characterized by a major eruption dated at 37.2 ± 1.5 kyr that spread a 30–40 cm thick fallout deposit over the flanks of Piton des Neiges and the western part of Piton de la Fournaise suggesting a massive island-scale impact on most components of the island terrestrial biodiversity 66 , 67 . Thus, the volcanic eruptions of Piton des Neiges may have triggered Mascarene petrel population declines, through a high mortality, breeding failures and, most importantly, the total disappearance of suitable breeding habitat 11 , 13 . Volcanic-related population declines and extinctions have also been reported for other birds’ species on other islands.…”

“…Volcanic-related population declines and extinctions have also been reported for other birds’ species on other islands. For instance, the volcanic activity at Deception Island resulted in the near-complete local extinction of the gentoo penguin colony on Ardley Island (Antarctic Peninsula) 12 ; the eruption of the Barcena volcano in San Benedicto (Revillagigedo Archipelago) resulted in the local extirpation of the Townsend’s shearwater 68 , and the recent violent eruption of Kasatochi volcano (central Aleutian archipelago) caused the local extinction of avian biodiversity 13 . After the latest eruption of Piton des Neiges abruptly ended, the Mascarene petrel appears not to have recovered to previous population levels.…”

“…Although this narrative assumes that populations of island endemics were abundant before human impact, this assumption is rarely tested as little pre-human colonization information on endemic fauna abundance is available. Natural events, such as historical climatic cycles 7 – 10 and island-scale volcanic eruptions 11 – 13 are also known to impact species distribution and abundance worldwide 14 . Hence, disentangling anthropogenic impacts from natural events is often limited by the lack of information about historical events that may have led to population collapse before human colonization.…”