Waterfowl Production on the Woodworth Station
in South-central North Dakota, 1965-1981

Table 16. Chronology of hatch dates during 15 years for upland-nesting ducks, Woodworth Study Area, 1967-81.

					Percent of unhatched nests before dates
Year	n	Earliest hatch date	Latest hatch date	Lengh of hatching season (days)	10 July	15 July	20 July	25 July	1 August
1967	11	13 June	10 August	59	82	73	46	36	36
1968	24	20 June	5 August	47	83	75	58	50	42
1969	75	16 May	11 August	88	37	28	20	13	9
1970	88	9 June	11 August	64	61	53	43	31	19
1971	114	5 June	12 August	69	62	47	27	22	12
1972	98	1 June	7 August	68	42	39	29	21	12
1973	45	7 June	29 July	53	56	42	27	24	4
1974	122	1 June	8 August	69	57	42	27	22	11
1975	141	1 June	4 August	65	50	43	28	20	13
1976	92	10 June	2 August	54	26	12	4	3	1
1977	70	20 May	31 July	73	30	17	9	3	1
1978	211	12 May	3 August	84	22	18	12	6	4
1979	54	23 May	24 July	63	20	17	9	2	0
1980	26	6 May	18 July	43	50	39	15	0	0
1981	57	28 May	19 July	53	35	19	7	0	0
Total per mean	1,228	1 June	2 August	63	43	33	22	15	9