( Food ( ( changes ( with ( ( seasons and ) whim ) ) ) . ) )
(ROOT (S (NP (NNP Food)) (VP (VBZ changes) (PP (IN with) (NP (NNS seasons) (CC and) (NN whim)))) (. .)))
Food changes with seasons and whim.
(ROOT (S (NP (NP (DT A) (NN change)) (PP (IN of) (NP (NP (NN season)) (CC and) (NP (JJR less) (NN food))))) (ADVP (RB usually)) (VP (VB cause) (S (NP (JJ certain) (NNS animals)) (VP (TO to) (VP (VB migrate))))) (. .)))
A change of season and less food usually cause certain animals to migrate.