The Guidelines and Help Center contain a lot of information about general cache placement and what you need to know. The information in this Wiki is based on these guidelines as applied to the British Overseas Territory of Gibraltar.
This large nature reserve is a protected area managed by the Gibraltar Ornithological & Natural History Society. The reserve has two sections, one (the larger) in the north and a smaller one in the south. Due to the sensitive nature of the flora and fauna in the reserve and the fact there are many archaeological features caches may only be placed with permission.
You may view the extent of the reserves in the Gibraltar Geo Portal Map (see screen shot below). When the map opens, tick the box on the left, Nature Reserve Area.
You can also download a KML file of the reserve from here - scroll down and find the file gibgis:nature_reserve_area_25830 then click the link KML on the right. KML files will open in Google Earth which is a free download for a PC and also as apps for Apple and Android.
Reviewer for Gibraltar - Lorgadh