> The problem is that a single unlocked door led to the termination of the animals. The problem is that this "can't" happen. Zoo animals in harsh climates alw

> The problem is that a single unlocked door led to the termination of the animals. The problem is that this "can't" happen. Zoo animals in harsh climates always sleep indoors in a big inner room heated. This main room can be accessed by a minimum of 2 doors. One (or several) leads to the external part of the exhibition. This play area will typically have a moat, that gradually gets deeper, and a high wall. Chimps are poor swimmers (they sink like a rock on water) and the wall is designed to avoid escapes. If the animals escape to this enclosure they can't proceed further and are not a danger for the public so shooting them wouldn't have any sense. The other door leads typically to a small logistics area, used to store needed stuff (brooms, fresh hay etc) or to interact with the animals safely. This small hall is accessed trough a second locked door. Sometimes you can't open the room door without locking first the pre-cage door. The design encourages having at least one locked door at any time. The building itself will typically have a main door, the third, to allow access from the outside One unlocked door means that the chimps will be contained in the broom's hall. Even with two unlocked doors this could end with the chimps trapped inside as long as you have solid windows (as expected in Sweden). In this case both locks were left opened at the same time, two or maybe three doors unlocked by night, in the middle of a harsh weather (any opened door would lead to a noticeable chill air current inside the building, or even maybe to the electronic heater system triggering automatically an alarm)