Need help in here :-)

I just wanted to advise of some clever maths people, I need to decide wether to use a 1 or 2 tailed test on the following question. What do you think I should use ? Heres the question..

Data on the DDT levels in a random sample of 10 falcons nesting in an area are given. On a second occasion 12 falcons were captured and ddt levels determined. Test the hypothesis that median levels of DDT was the same on both occasions?

Thanks alot for any reply :-)

does it matter which test you use in this question

but i'd use the two tail one