Redhawk Caldera giraffes are unable to cough.

Nightjar didn't move as Fin had thought he would.  She had clearly underestimated his strength as he stood solid against her push.  She did at least manage to knock him off his center, and though she hesitated out of surprise at her lack of total victory, she recovered quickly enough.  She felt his grip loosen upon her and with a twist of her head to try and snare the boy's scruff, she shoved against him again in hopes of knocking him further back where she could try again to overtake him then.