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Grassland Bird Surveys in North Valley County and Northwest Phillips County, Montana:
2011 Summary
Prepared for:
USDI Bureau of Land Management
Montana-Dakotas Office
Paul Hendricks, Susan Lenard, Coburn Currier
Montana Natural Heritage Program
P.O. Box 201800
1515 East Sixth Avenue
Helena, MT 59620-1 800
January 2012
1
Introduction
This report provides a summary of activities and results for two point-count surveys for
grassland birds conducted by the Montana Natural Heritage Program during summer 2011 in
north-central Montana for the Montana-Dakotas Office of the Bureau of Land Management
(Figure 1). All lands in both counties on which Heritage point-count surveys were conducted are
administered by the Bureau of Land Management
Points surveyed in north Valley County are from a set of 39 point-count transects (three point-
counts per transect) selected in 2008 from 69 transects originally established and surveyed in
2001 (Hendricks et al. 2008). The original 69 transects were run every year during 2001-2007,
the subset of 39 every year since 2007. In both the original set of transects and the subset, some
transects were not sampled due to weather, accessibility, or other logistical issues. In 201 1 we
sampled 82% (32) of the 39 transects planned for survey.
Points surveyed in northwestern Phillips County followed the same point-count protocol as for
the north Valley County survey (see Hendricks et al. 2008 for details), but the survey was part of
a larger effort spread across Phillips and Valley counties to investigate the effects of grazing
intensity on grassland bird abundance and habitat use. Our point locations were chosen to help
fill areas where prior survey effort had been minimal to non-existent. The count protocol
differed from the longer-term dataset for north Valley County in that the Phillips County points
were stand-alone (isolated) rather than part of three-point transects. This was done to provide
better aerial coverage of the region, given survey time-constraints and commitments to other
projects. The Heritage contribution was 54 point counts to the larger survey effort of this
project.
Digital photographs and vegetation data (indices of height, density, cover) associated with each
point were also collected, but will not be addressed in this summary report. All data (geo-
referenced points, bird counts, vegetation, photographs) have been added to the Heritage
Program databases and shared with the BLM.
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Results and Discussion
North Valley County
Table 1. List of bird species detected on or flying over 100 m radius points in north Valley
County, Montana during 2011; total points = 96. Species are listed in order of relative
abundance of points on which detected. Montana Species of Concern are bolded.
1 Species (on points)
#Points
% Points
individuals
Chestnut-collared Longspur
93
97
417
1 Horned Lark
73
76
173
Baird's Sparrow
66
69
110
Sprague's Pipit
60
63
97
Western Meadowlark
39
41
88
Grasshopper Sparrow
26
27
34
McCown's Longspur
22
23
31
Marbled Godwit
21
22
41
Vesper Sparrow
20
21
25
Brown-headed Cowbird
19
20
50
Lark Bunting
18
19
53
Bobolink
13
14
28
Brewer's Sparrow
13
14
24
Savannah Sparrow
13
14
21
Wilson's Phalarope
10
10
16
Willet
9
9
13
Barn Swallow
5
5
9
Kill deer
5
5
6
Northern Pintail
5
5
7
Northern Harrier
4
4
6
Northern Shoveler
4
4
6
Eastern Kingbird
3
n
D
3
Mallard
3
3
4
Red-winged Blackbird
3
3
6
Brewer's Blackbird
2
2
3
Long-billed Curlew
2
2
2
Short-eared Owl
2
2
2
Blue-winged Teal
1
1
2
Lesser Scaup
1
1
1
Sora
1
1
1
Wilson's Snipe
1
1
1
4
We sampled 96 points on 32 transects in 2011. Seven transects (21 points) were not surveyed
due to rain and inaccessible roads during the time we had available for doing surveys. Counts
were conducted from 5 June to 12 July, when we would typically have finished them by the end
of June under more favorable conditions. However, the weather in 201 1 also appeared to delay
onset of breeding activities by some species, so count results were not unusually biased by
reduced detections due to a lack of singing. On the contrary, occupancy rates for some species,
such as Baird’s Sparrow and Bobolink, were high relative to other years.
We detected 3 1 species on or flying over the point-count circles (Table 1). We noted an
additional eight species during counts that were beyond count boundaries. In order of occupancy
(number of points) these eight species were Upland Sandpiper (3), Clay-colored Sparrow (2),
Burrowing Owl (1), Canada Goose (1), Common Nighthawk (1), Ring-necked Pheasant (1),
Swainson’s Hawk (1), and Yellow-headed Blackbird (1).
Ten species occupied at least 20% of the points sampled (Table 1), with Chestnut-collared
Longspur being the most prevalent; this species has had the greatest rate of point occupancy
during all 1 1 years of surveys in north Valley County. Within the group often species with
occupancies > 20% are five that are Montana Species of Concern (SOC) through 2011.
Northwestern Phillips County
We sampled 54 points in 201 1 ; point counts were conducted during 20 June to 1 July. Our
access to points was somewhat hampered by road conditions made difficult due to excessive
rains and flooding in June, a situation also encountered in north Valley County.
We detected 3 1 species on or flying over the point-count circles (Table 2). We noted an
additional seven species during counts that were beyond count boundaries. In order of
occupancy (number of points) these seven species were Ring-necked Pheasant (3), Upland
Sandpiper (3), American Coot (1), Canada Goose (1), Eared Gi'ebe (1), Ring-necked Duck (1),
and Sharp-tailed Grouse (1).
Seven species occupied at least 20% of the points sampled (Table 2), with Chestnut-collared
Longspur being the most prevalent, as it was in north Valley County. Five of the remaining six
species (Horned Lark, McCown’s Longspur, Baird’s Sparrow, Grasshopper Sparrow, Marbled
Godwit) were also present on at least 20% of the points in north Valley County (Table 1), the
exception being Lark Bunting on 20% of Phillips County points and 19% of Valley County
points. Six species with occupancy rates of at least 15% are Species of Concern as of 201 1 (both
longspur species, Baird’s Sparrow, Grasshopper Sparrow Lark Bunting, and Sprague’s Pipit).
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Table 2. List of bird species detected on or flying over 100 m radius points in northwestern
Phillips County, Montana during 2011; total points = 54, Species are listed in order of relative
abundance of points on which detected. Montana Species of Concern are bolded.
Species (on points)
# Points
Yo Points
individuals
Chestnut-collared Longspur
52
96
282
Horned Lark
48
89
119
McCown's Longspur
26
48
32
Baird's Sparrow
24
44
44
Grasshopper Sparrow
19
35
30
Marbled Godwit
15
28
30
Lark Bunting
11
20
38
Sprague's Pipit
10
19
19
Western Meadowlark
9
17
21
Vesper Sparrow
8
15
11
Willet
8
15
15
Northern Pintail
5
9
7
Blue-winged Teal
4
7
8
Red-winged Blackbird
4
7
6
Brewer's Blackbird
3
6
5
Brown-headed Cowbird
3
6
4
Long-billed Curlew
3
6
5
Wilson's Phalarope
3
6
8
Killdeer
2
4
2
Northern Shoveler
2
4
2
Savannah Sparrow
2
4
2
American Avocet
1
2
1
Brewer's Sparrow
1
2
1
Cliff Swallow
1
2
1
Common Crackle
1
2
1
Ferruginous Hawk
1
2
1
Gadwall
1
2
1
Mallard
1
2
1
Northern Harrier
1
2
1
Ring-billed Gull
1
2
1
Swainson's Hawk
1
2
1
Striking differences between the two counties in occupancy rates included McCown’s Longspur
(48% in Phillips, 23% in Valley), Baird’s Sparrow (44% in Phillips, 69% in Valley), Sprague’s
Pipit (19% in Phillips, 63% in Valley), and Bobolink (0% in Phillips, 14% in Valley). These
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results suggest less grass height and density (less precipitation?) across the landscape in Phillips
County in 201 1 in contrast to Valley County.
For the two counties, average number of individuals per count on points where detected was
more uniform than were occupancy rates for three of the above species (Bobolink was excluded
because of zero detections in Phillips County). Mean counts for McCown’s Longspur were 1.2
in Phillips County and 1.4 in Valley County, for Baird’s Sparrow 1.8 in Phillips and 1 .7 in
Valley, and for Sprague’s Pipit 1.9 in Phillips and 1.6 in Valley. For the ten species with the
highest occupancy rates in both counties (including Lark Bunting but excluding Brown-headed
Cowbird, which had few detections in Phillips County), the mean number of individuals per
occupied count in both counties was highly correlated (r -= 0.985, P < 0.0001). Thus, the spatial
distribution of each species differed more between the two counties in 201 1 than their average
abundances at the local scale when they occurred.
Reference Cited
Hendricks, P., S. Lenard, C. Currier, B. A. Maxell, and J. Carlson. 2008. Surveys for grassland
birds of the Malta Field Offlce-BLM, including a seven-year study in north Valley
County. Report to the Bureau of Land Management. Montana Natural Heritage
Program, Helena, MT. 26 pp. plus appendices.
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