Eft > 1.five m above the ground) by both species. Error bars represent regular error, and distinct letters indicate that signifies differ with p < 0.05. doi:10.1371/journal.pone.0156180.gNest predationAfter 14 days, the total number of eggs surviving on removal treatments was higher than on unmanipulated treatments (F(1,10) = 5.29, p = 0.04, Fig 2). The total number of eggs attacked by rodents on removal sites was also lower than on unmanipulated sites (F(1,10) = 7.22, p = 0.02, Fig 3), but there was no difference in the percentage of eggs attacked by birds on removal andFig 2. Nest survivorship. Average percentage of nests surviving with eggs intact per 1-ha site after 14 days. Error bars represent standard error and different letters represent treatments (unmanipulated or black rats removed) with means that are significantly different at p < 0.05. doi:10.1371/journal.pone.0156180.gPLOS ONE | DOI:10.1371/journal.pone.0156180 June 13,7 /Nest Predation by Commensal RodentsFig 3. Nest predation by rodents. Average percentage of nests with eggs attacked per 1-ha site by rodents after 14 days. Error bars represent standard error and different letters represent treatments (unmanipulated or black rats removed) with means that are significantly different at p < 0.05. doi:10.1371/journal.pone.0156180.gunmanipulated sites (F(1,10) = 2.12, p = 0.17). Around half of all attacks on eggs were from birds: 56.7 ?5.0 of eggs were attacked by birds on unmanipulated sites (n = 162 nests), compared with 48.6 ?7.8 on removal sites (n = 69 nests). Less than 20 of nest attacks were made by rats: 14.0 ?3.8 of eggs were attacked by rats on unmanipulated sites (n = 35 nests), compared with a single nest on removal sites. Less than 10 of nest attacks were made by brushtail possums: 4.8 MedChemExpress CC122 PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21107380 ?two.6 on unmanipulated web sites (n = 12 nests), compared with four.7 ?3.two on removal web sites (n = 5 nests). The remainder of attacks incorporated ringtail possum, ants and unidentified markings.Effect sizeWe calculated an effect size of 1.3 using the total variety of eggs surviving immediately after two weeks on unmanipulated and removal web sites. When in comparison with the imply impact size estimates of Salo et al. [46], calculated from analogous experiments on prey responses to removals of native and introduced predators, our effect size estimate of 1.3 falls inside the expected variety (1.224?three.046) for an `exotic’ predator (see Fig 1 of [46]).DiscussionThis study will be the initially to quantify the predatory impacts of black rats on arboreal nesting birds in Australia within a method exactly where black rats have replaced native rodent counterparts. Constant with our predictions, black rats contributed significantly to nest attacks, and as a result seem likely to contribute an additive supply of nest mortality for modest birds in urban habitat remnants.Black rats are more arboreal than native bush ratsBlack rats left around 5 times additional spool line in trees than bush rats, thus supporting preceding conjecture that black rats make use of the arboreal zone much more than bush rats. Black rats arePLOS One particular | DOI:10.1371/journal.pone.0156180 June 13,eight /Nest Predation by Commensal Rodentswell known for their arboreal activity [67], but our spooling data quantify for the initial time the minimal arboreal activity of bush rats. Differences in climbing capacity among two potentially scansorial congeners are usually attributed to weight and dominance, exactly where the smaller sized subdominant species tends to climb much more than the bigger dominant species [68, 69].