The ghost of invasives past: rat eradication and the community composition and energy flow of island bird communities

Abstract

Abstract. In the Falkland Islands, islands with invasive rats have fewer passerine species compared to islands without rats. On islands on which rats have been eradicated, passerine species richness is indistinguishable from that found on islands historically free of rats, but community composition differs between these two island types. In particular, the most dominant species on historically rat-free islands, Cinclodes antarcticus, is less abundant and prevalent on eradicated islands. We compared passerine energy flow on islands with rats, islands from which rats have been eradicated, and islands on which rats were historically absent. Passerine communities on islands historically without rats used nine times more energy than on islands with rats present. Despite equivalent passerine species richness, passerine energy flow was approximately half on islands from which rats had been eradicated compared to historically rat-free islands. Because passerine energy flow was determined by community composition and not by species richness, passerine species within this community appear to be functionally complementary and not functionally redundant. At least one species, C. antarcticus, plays an irreplaceable role. Our results also document the dramatic and lingering effects of invasive species following their eradication, and the importance of species complementarity for the resilience of community properties.

Mixed ancestry from wild and domestic lineages contributes to the rapid expansion of invasive feral swine

“…Furthermore, IAS pose a significant threat to biodiversity by negatively impacting native species through predation and competition (Human & Gordon, 1996;Leighton, Horrocks, & Kramer, 2011;Lowe, Browne, Boudjelas, & De Poorter, 2000;Wilcove, Rothstein, Dubow, Phillips, & Losos, 1998;Wiles, Bart, Beck, & Aguon, 2003). In extreme cases IAS can completely reconfigure ecosystems through the exclusion of foundation species, alteration of disturbance regimes, displacement of entire native communities or formation of alien monocultures (Balch, Bradley, D'Antonio, & Gomez-Dans, 2013;Bankovich, Boughton, Boughton, Avery, & Wisely, 2016;Ellison et al, 2005;Hutchinson & Vankat, 1997;Tabak, Poncet, Passfield, Goheen, & Del Rio, 2016;Wiles et al, 2003). In the United States (US), as many as 87% of imperiled species are directly threatened by IAS (McClure, Burdett, Farnsworth, Sweeney, & Miller, 2018).…”

Indirect effects of invasive rat removal result in recovery of island rocky intertidal community structure

“…Invasive animal impacts are particularly disruptive on islands because islands usually have small numbers of species resulting in simplified food chains and limited functional redundancy, and those species typically have limited evolved defenses against herbivory, predation, and competition 6 . The direct effects of invasive animals on islands are well documented [7][8][9][10][11] , and there is increasing evidence of their multiple indirect effects as well 6,[12][13][14][15] .…”