Disease and competition, not just predation, as drivers of impacts of the black rat (Rattus rattus) on island mammals

• Published in: Global ecology and biogeography 2014-12, Vol.23 (12), p.1485-1488
• Main Authors: Smith, Helen M, Banks, Peter B
• Format: Article
• Language: English
• Subjects: alien; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Competition; Conservation biology; CORRESPONDENCE; disease; Ecological competition; Ecological invasion; Ecosystems; Fundamental and applied biological sciences. Psychology; General aspects; Introduced species; Islands; Mammalia; Mammals; Parasites; Predation; Predators; Rats; Rattus rattus; Rodents; Species extinction; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 1466-822X; 1466-8238
• DOI: 10.1111/geb.12220

Hanna & Cardillo (2014) report an association between the presence of black rats (Rattus rattus) and extinctions of endemic mammals on Australian islands. Although we agree that introductions of the black rat are likely to have had a significant impact on island ecosystems, we suggest that there is little empirical support for their main conclusion, that predation (and thus mesopredator processes) is the causal mechanism driving the association between the presence of black rats and extinctions of native mammals on Australian islands. We present a brief literature review of evidence for two alternative mechanisms – introduction of novel diseases and competition – which suggest there are multiple explanations for how native mammal extinctions on Australian islands may have occurred. The potential impact of these processes interacting across different trophic levels is rarely considered, but is applicable across many different ecosystems world‐wide.