On Bunny Island, there are lots of bunnies. Right now (consider this $t=0$), there are $253$ thousand bunnies on Bunny Island.
Over the next $5$ years, bunnies will die at a rate of $D(t)=10000+5000\sin(2t)$, and bunnies will be born at a rate of $B(t)=15000+10000\cos(2t)$, where both rates are given in number of bunnies per year.
At what rate will the bunny population be changing in $5$ years?
Please round answer to the nearest whole bunny.