Do not use the aggregate First function. It is not a reliable
function to use, and does not really do what you think does.


Instead, try the aggregate Min function. You can use the Min function
on the Date field you have to return the first date for a particular
an animal was detected.

Side note, you want to consider renaming that field, "Date" is a
reserved word for Access and can cause problems using it as a field
name.