Creationists accept that animals adapt, that their bodies and behaviours change over time.

...well how do you logically decide where small changes compounded over generations and time stop and cannot become larger changes?
What prevents small compounding changes from becoming the large changes that evolution describes?
What mechanism does the creationist identify which allows change over generations of up point X but no farther?

Isn't that just like accepting that there are seconds and minutes but then denying that enough of those become an hour and enough of those become a day?