IF THE CAPITOL ARE FRUSTRATED BY MOCKINGJAYS AND HATE THEM THEN WHY ARE THERE A SH*TLOAD OF THEM IN THE 74TH ARENA??

They really never said why but I think because the Capitol thought they are just song birds. I mean the Jabber Jays lost there ability of speaking when they mated with the mocking birds. So the Capitol stopped thinking them as a threat .Katniss though used the Mocking Jays as a weapon. My 2nd opinion is that the Capitol might have wanted to finish them of. What I mean is this: Since the birds were taken from there homes and were freed in the arena the birds wouldn't know where the food was. Plus there was mutts and stuff so the birds were more endangered in the arena then they were in there natural habitat. Also, for the contestants who were playing and were good with a bow and arrow might have tried to kill a few and eat them or they might attack them with the element of surprise.

this is continued from my last answer.
How were they supposed to know that the jabberjay's were going to survive and mate with the mockingbirds to become MockingJay's. Although, Katniss does use the iconic mockingjay as a weapon against the capitol and they obviously filled the arena with MockingJay's so that in my opinion- they fill it to torture them for using the icon as a weapon against them x ( love the hunger games forever)

I know right!!!