The increase in rats, which is a real one, is mostly down to the warm Summer and Autumn, according to reports from the pest control industry. This has boosted their breeding success and also made them more visible when they seek out water every day. It is a national trend and includes a very large number of areas where there has been no new recycling system introduced.
There might possibly be a small contribution from additional, highly irresponsible and of course illegal, fly tipping after the introduction of the new recycling system. Similarly slightly more uncollected material due to people being unwilling or unable to cooperate or respond correctly to the new system may contribute a little to the problem. Heightened awareness of waste and the public debate on rats may also lead more people to report rat issues.
Of course urban rats thrive when people are irresponsible with their waste eg through littering and provide rats with plenty of food!
Credit where credit is due, Councillor Hopkins has overseen the introduction of system which has very significantly boosted Bristol's recycling rate and cut some environmental impacts as a result. Its not a perfect system and the city still has some way to go to match the very high recycling rates found in other European cities but we should all be pleased that we have made a big improvement and are finally heading in the right direction.