For those who breed birds in outdoor aviaries, mice patrol is generally a routine activity involving setting and monitoring traps. It is predicted that one of the unwelcome results of El Niño will be an increase in the populations of field mice. As winter approaches, these mice will be seeking new shelter and new food sources, and invading outdoor aviaries. As they climb support posts, run along wire cage edges and drop into food bowls, they leave a trail of urine and feces that contaminate the aviary with bacteria which compromises our birds' health. In order to control this invasion, certain measures are needed.

Check the aviary and remove all extraneous materials such as discarded perches, used nest boxes and especially wasted foodstuffs. The object is to eliminate hiding places and a food source for the mice. Check and clean nest boxes, taking down those that will not be used by the pairs for shelter or sleeping. The placement of modern mouse traps along their favorite runways ensures that they will enter the traps and be captured. Some builders of nest boxes also make mouse traps. The modern trap generally keeps the mouse inside; once it has entered, there is no means of escape. These mice must then be disposed of. For outside aviaries without small mesh wire on the ground and walls, rats can become a problem also. Rats not only carry diseases but will attack and kill smaller parrots, such as Senegals. Storing nuts and grains in mouse- and rat-proof containers helps keep the bird foods safe from bacterial contamination. Cleaning up any spilled grains or food residues reduces the interest of rodents in the aviaries.

Reports from Arizona and Texas indicate that killer bees are attacking and killing both domestic and wild animals. It is reported that dogs and horses, as well as humans, have been attacked. In South America, these bees have killed people who were unfortunate enough to disturb them and were unable to outrun them to safety. The ferocity and intensity of these African exports is hard to imagine, but descriptions of attacks by those who have been present indicate that they are persistent and attack in great clouds, leaving thousands of stings on their victims. Apparently they attack any live creature that disturbs them. It is reported by the news media that they are eventually expected to migrate to most of the southern and southwestern states in the United States.

Bird breeders with outside aviaries in areas where these bees exist are urged to place window screening material around their aviaries to prevent these bees from entering. Emil Musil of Arizona has written about his tragic experience with these bees that swarmed past his aviaries. Within a few minutes, his entire breeding collection of American Singer canaries lay dead in their aviary. His story was published in the November 1998 American Singer Club newsletter. In addition to protection from killer bee stings, window screening protects the birds from disease transmission via mosquito bites and pigeon fly bites. This screening also helps keep out regular flies which can deliver bacteria to food bowls.