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Effects of Grazing and Burning on Densities and
Habitats of Breeding Ducks in North Dakota

Tables

Table 1. Number of nests and initiation dates for waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Species Nests^a
n Initiation date^b

Median (90-percentile range)^c

Mallard 881 7 May (20 Apr-3 Jun)

Gadwall 489 2 Jun (19 May-17 Jun

Blue-winged teal 435 24 May (11 May-14 Jun)

American wigeon 232 28 May (12 May-11 Jun

Lesser scaup 222 13 Jun (3 Jun-26 Jun)

Northern pintail 154 26 Apr (14 Jun-21 May)

Northern shoveler 91 17 May (4 May-6 Jun)

Green-winged teal 7^d

Canvasback 1^d

^aTotal number of nests found; not all were used for analyses.
^bEstimated date of nest initiation.
^cMedian date of nest initiations and 90-percentile range in dates.
^dInsufficient data to provide median or range.

Table 2. Mean values of annual nest density (nests/ha) of 7 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Mallard Gadwall Blue-winged
teal Lesser
scaup American
wigeon Northern
shoveler Northern
pintail

Treatment

Control 0.25 0.11 0.09 0.05 0.05 0.02 0.04

Spring graze 0.21 0.18 0.10 0.05 0.05 0.01 0.03

Spring burn 0.21 0.10 0.08 0.09 0.04 0.07 0.06

Summer burn/spring graze 0.17 0.13 0.13 0.06 0.05 0.02 0.02

Year^a

1980 0.36A 0.18 0.14 0.08 0.06BC 0.02 0.05

1981 0.40A 0.14 0.12 0.05 0.12A 0.03 0.07

1982 0.31A 0.12 0.09 0.04 0.08B 0.04 0.08

1983 0.17BC 0.06 0.10 0.02 0.06BC 0.01 0.03

1984 0.20B 0.11 0.10 0.05 0.04CD 0.01 0.02

1985 0.11BC 0.13 0.12 0.06 0.03CD 0.03 0.02

1986 0.09C 0.11 0.08 0.05 0.03CD 0.02 0.18

1987 0.16BC 0.12 0.11 0.06 0.05BCD 0.03 0.03

1988 0.08C 0.07 0.04 0.03 0.03D 0.01 0.01

^aColumn means not sharing the same letter differ (P </= 0.05).

Table 3. Least-squares means of daily nest survival rate (DNSR) and Mayfield (%) estimate of nest success of 3 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Mallard Gadwall Blue-winged teal

DNSR Mayfield
estimate DNSR Mayfield
estimate DNSR Mayfield
estimate

Average 0.970 34.5 0.977 44.7 0.966 31.3

Treatment

Control 0.967 31 0.981 51 0.955 20

Spring graze 0.961 25 0.974 40 0.966 30

Spring burn 0.974 40 0.950 17 0.958 22

Summer burn/spring graze 0.964 28 0.982 52 0.985 58

Year^a

1980 0.972A 37 0.982AB 53 0.984 58

1981 0.977A 44 0.971AB 35 0.965 30

1982 0.944BC 13 0.959AB 23 0.939 12

1983 0.961ABC 25 0.968AB 32 0.977 45

1984 0.969AB 33 0.972AB 36 0.971 36

1985 0.942BC 12 0.927B 7 0.952 19

1986 0.978A 50 0.983AB 56 0.973 40

1987 0.981A 51 0.990A 71 0.973 39

1988 0.966AB 30 0.984AB 56

^aColumn means not sharing the same letter differ (P </= 0.05).

Table 4. Proportions of duck nests found in vegetation types and availability of vegetation types at Lostwood National Wildlife Refuge, North Dakota in 1981 and 1987.

Year Vegetation type Available Mallard Gadwall Blue-winged teal

1981

Brush 0.07 0.61 + 0.28 + 0^b

Brush/grass 0.42 0.34 0.58 + 0.27

Grass/brush 0.16 0.02 - 0.02 - 0.31

Grass/forbs 0.27 0.01 - 0.04 - 0.37

Forbs 0.02 0 0.01 0.02

Shallow marsh emergent 0.05 0.02 - 0.06 0.03

1987

Brush 0.04 0.50 + 0.44 + 0^b

Brush/grass 0.25 0.38 0.32 0.11 -

Grass/brush 0.44 0.11 - 0.11 - 0.49

Grass/forbs 0.21 0.01 - 0.07 - 0.19

Forbs 0.03 0 0.04 0.15

Shallow marsh emergent 0.03 0 0.04 0.06

^a + indicates the habitat is preferred (P < 0.05); - indicates the habitat is avoided (P < 0.05).
^bBrush was not tested for blue-winged teal. Because no nests were found in this vegetation type, it was not considered suitable nesting habitat for blue-winged teal.

Table 5. Proportions of duck nests found in vegetation types and availability of vegetation types at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Vegetation type Available^a American wigeon Lesser scaup Northern pintail Northern shoveler

Brush 0.06 0.39 0 0.20 0.01

Brush/grass 0.33 0.56 0.32 0.60 0.21

Grass/brush 0.30 0.03 0.29 0.13 0.35

Grass/forbs 0.24 0.01 0.24 0.06 0.31

Forbs 0.02 0.01 0.02 0 0.02

Shallow marsh emergent 0.04 0.01 0.13 0.01 0.11

^aAvailable vegetation is based on mean of 1981 and 1987 data.

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Species	Nests^a n	Initiation date^b
Species	Nests^a n	Median	(90-percentile range)^c
Mallard	881	7 May	(20 Apr-3 Jun)
Gadwall	489	2 Jun	(19 May-17 Jun
Blue-winged teal	435	24 May	(11 May-14 Jun)
American wigeon	232	28 May	(12 May-11 Jun
Lesser scaup	222	13 Jun	(3 Jun-26 Jun)
Northern pintail	154	26 Apr	(14 Jun-21 May)
Northern shoveler	91	17 May	(4 May-6 Jun)
Green-winged teal	7^d
Canvasback	1^d
^aTotal number of nests found; not all were used for analyses. ^bEstimated date of nest initiation. ^cMedian date of nest initiations and 90-percentile range in dates. ^dInsufficient data to provide median or range.

	Mallard	Gadwall	Blue-winged teal	Lesser scaup	American wigeon	Northern shoveler	Northern pintail
Treatment
Control	0.25	0.11	0.09	0.05	0.05	0.02	0.04
Spring graze	0.21	0.18	0.10	0.05	0.05	0.01	0.03
Spring burn	0.21	0.10	0.08	0.09	0.04	0.07	0.06
Summer burn/spring graze	0.17	0.13	0.13	0.06	0.05	0.02	0.02
Year^a
1980	0.36A	0.18	0.14	0.08	0.06BC	0.02	0.05
1981	0.40A	0.14	0.12	0.05	0.12A	0.03	0.07
1982	0.31A	0.12	0.09	0.04	0.08B	0.04	0.08
1983	0.17BC	0.06	0.10	0.02	0.06BC	0.01	0.03
1984	0.20B	0.11	0.10	0.05	0.04CD	0.01	0.02
1985	0.11BC	0.13	0.12	0.06	0.03CD	0.03	0.02
1986	0.09C	0.11	0.08	0.05	0.03CD	0.02	0.18
1987	0.16BC	0.12	0.11	0.06	0.05BCD	0.03	0.03
1988	0.08C	0.07	0.04	0.03	0.03D	0.01	0.01
^aColumn means not sharing the same letter differ (P </= 0.05).

	Mallard		Gadwall		Blue-winged teal
	DNSR	Mayfield estimate	DNSR	Mayfield estimate	DNSR	Mayfield estimate
Average	0.970	34.5	0.977	44.7	0.966	31.3
Treatment
Control	0.967	31	0.981	51	0.955	20
Spring graze	0.961	25	0.974	40	0.966	30
Spring burn	0.974	40	0.950	17	0.958	22
Summer burn/spring graze	0.964	28	0.982	52	0.985	58
Year^a
1980	0.972A	37	0.982AB	53	0.984	58
1981	0.977A	44	0.971AB	35	0.965	30
1982	0.944BC	13	0.959AB	23	0.939	12
1983	0.961ABC	25	0.968AB	32	0.977	45
1984	0.969AB	33	0.972AB	36	0.971	36
1985	0.942BC	12	0.927B	7	0.952	19
1986	0.978A	50	0.983AB	56	0.973	40
1987	0.981A	51	0.990A	71	0.973	39
1988	0.966AB	30	0.984AB	56
^aColumn means not sharing the same letter differ (P </= 0.05).

Year	Vegetation type	Available	Mallard	Gadwall	Blue-winged teal
1981
	Brush	0.07	0.61 +	0.28 +	0^b
	Brush/grass	0.42	0.34	0.58 +	0.27
	Grass/brush	0.16	0.02 -	0.02 -	0.31
	Grass/forbs	0.27	0.01 -	0.04 -	0.37
	Forbs	0.02	0	0.01	0.02
	Shallow marsh emergent	0.05	0.02 -	0.06	0.03
1987
	Brush	0.04	0.50 +	0.44 +	0^b
	Brush/grass	0.25	0.38	0.32	0.11 -
	Grass/brush	0.44	0.11 -	0.11 -	0.49
	Grass/forbs	0.21	0.01 -	0.07 -	0.19
	Forbs	0.03	0	0.04	0.15
	Shallow marsh emergent	0.03	0	0.04	0.06
^a + indicates the habitat is preferred (P < 0.05); - indicates the habitat is avoided (P < 0.05). ^bBrush was not tested for blue-winged teal. Because no nests were found in this vegetation type, it was not considered suitable nesting habitat for blue-winged teal.

Vegetation type	Available^a	American wigeon	Lesser scaup	Northern pintail	Northern shoveler
Brush	0.06	0.39	0	0.20	0.01
Brush/grass	0.33	0.56	0.32	0.60	0.21
Grass/brush	0.30	0.03	0.29	0.13	0.35
Grass/forbs	0.24	0.01	0.24	0.06	0.31
Forbs	0.02	0.01	0.02	0	0.02
Shallow marsh emergent	0.04	0.01	0.13	0.01	0.11
^aAvailable vegetation is based on mean of 1981 and 1987 data.

Effects of Grazing and Burning on Densities and Habitats of Breeding Ducks in North Dakota

Tables

Effects of Grazing and Burning on Densities and
Habitats of Breeding Ducks in North Dakota