If an encounter can entail more than one crocodile, then you haven't set up your tables correctly. You need one more.
First let's define some things, and seperate the idea of a Location from an Encounter. A lot of the issue (for everyone involved in this thread) is not realizing that those are 2 distinct things:
Crocodile - 1 reptilian animal
Location - A specific place at a specific time
Encounter - A crocodile at a location (using definitions from above)
You have many crocodiles which can be at many locations. You have many locations which can have many crocodiles. To sort out which crocodile is at which location on a specific day you need a new table to do so. Thus the Encounter table.
Here's the overview of how I see these 3 tables:
Crocodile
CrocID, sex, other data related to the crocodile throughout its existance
Location
LocationID, LocationDateTime, GPS, City, state, zip, all other data related to that specific place and time
Encounter
LocationID, CrocID, Alive, Height, Weight, all other data related to that crocodile at that location at that time
That sorts out what croc was seen where and when. You can't do it in just 2 tables if a location can have multiple crocs.