Reinvasion by ship rats (Rattus rattus) of forest fragments after eradication

摘要: Reinvasions provide prime examples of source-sink population dynamics, and are a major reason for failure eradications invasive rats from protected areas. Yet little is known about the origins structure replacement compared with original one. We eradicated eight populations ship separate podocarp-broadleaved forest fragments surrounded by open grassland (averaging 5.3 ha, scattered across 20,000 ha) in rural landscapes Waikato, New Zealand, monitored the- re-establishment new populations. Rats were kill-trapped to extinction during January April 2008, then again after reinvasion April–May (total n = 517). carrying Rhodamine B dye (n 94), available only baits placed 1–2 months advance adjacent source areas located 170–380 m (average 228 edge edge) away, appeared 7 8 first day eradication. The distribution age groups, genders proportions reproductively mature adults (more immature juvenile males fewer fully old females) was different among marked all other (P 0.001, 509); caught on days 7+ eradication 1–6 0.000); total sample collected trapping local brief, fixed-schedule sampling continuous forests 0.000). Genotyping 493 carcases found no significant population-level differentiation fragments, confirming that belonged single dynamic metapopulation. Marked both travelled up 600 few days. Conservation compromised problem cannot be prevented rapidly reinvading any cleared area