Have you seen a rat?

There are many Black Rats (Rattus rattus) around this year (2022), and quite a few are being found outdoors and moribund. That is typically because they are dying from anti-coagulant rodenticides.  If you see a rat out in daytime, some action is desirable.

The readily available 'second generation' anti-coagulants such as Brodifacoum and Bromadiolone (also Difenacoum and Difethialone) make the rats and their carcasses dangerous to birds. Many owls and other predatory birds have been killed.  You can do two things to reduce this impact.

  1. Dispose of the rat where birds cannot get the carcass (killing the ones that are still alive will reduce their suffering);
  2. Use, and encourage others to use, less damaging rodent control methods. Other methods include exclusion barriers (eg rat-proof your compost bin and chook yard/feeder), setting traps, or using baits containing safer chemical agents. First generation anti-coagulants such as Warfarin (also maybe Chlorophacinone or Diphacinone), are usually available from the same outlets that sell second generation compounds. In some cases, non-anticoagulant toxins may be in use, i.e. bromethalin, cholecalciferol and zinc phosphide but these are rarely available for household use.


Most photos of small terrestrial mammals submitted to Canberra Nature Map for identification that were photographed in the Canberra suburban area are of a Black Rat (Rattus rattus).  The next most likely species is the House Mouse (Mus musculus). Outside the city, at present, photos of Black Rats outnumber all other small mammal photos combined. However you may have found something different.  Here are some tips for what to include in your photos to increase the potential for correct identification:

  • An image that is sharp, not blurry;
  • A scale;
  • A view of the whole animal (preferably stretched out if it is a carcass);
  • Views of every surface -  (not always possible but ideally this includes a profile of the head, good views of the ears, the belly, the pads on the hind feet, and a good view of the fur and  skin on the tail from below and above);
  • Views of the teeth; and
  • A count of the number of teats.