They will whistle when they hear you as an encouragement for you to give them a treat like leaf lettuce.
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	3	nsubj	3:nsubj	_
2	will	will	AUX	MD	VerbForm=Fin	3	aux	3:aux	_
3	whistle	whistle	VERB	VB	VerbForm=Inf	0	root	0:root	_
4	when	when	ADV	WRB	PronType=Int	6	advmod	6:advmod	_
5	they	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	6	nsubj	6:nsubj	_
6	hear	hear	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	advcl	3:advcl:when	_
7	you	you	PRON	PRP	Case=Acc|Person=2|PronType=Prs	6	obj	6:obj	_
8	as	as	ADP	IN	_	10	case	10:case	_
9	an	a	DET	DT	Definite=Ind|PronType=Art	10	det	10:det	_
10	encouragement	encouragement	NOUN	NN	Number=Sing	3	obl	3:obl:as	_
11	for	for	SCONJ	IN	_	14	mark	14:mark	_
12	you	you	PRON	PRP	Case=Nom|Person=2|PronType=Prs	14	nsubj	14:nsubj	_
13	to	to	PART	TO	_	14	mark	14:mark	_
14	give	give	VERB	VB	VerbForm=Inf	10	acl	10:acl:to	_
15	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	14	iobj	14:iobj	_
16	a	a	DET	DT	Definite=Ind|PronType=Art	17	det	17:det	_
17	treat	treat	NOUN	NN	Number=Sing	14	obj	14:obj	_
18	like	like	ADP	IN	_	20	case	20:case	_
19	leaf	leaf	NOUN	NN	Number=Sing	20	compound	20:compound	_
20	lettuce	lettuce	NOUN	NN	Number=Sing	17	nmod	17:nmod:like	SpaceAfter=No
21	.	.	PUNCT	.	_	3	punct	3:punct	_
