hindy_mangione_keys-vegetative effects_finalv1.2 (1) pdf

Vegetative effects on grassland bird biodiversity in Southwest Michigan

MICHAEL HINDY, Cornerstone University, 1001 E Beltline NE, Grand Rapids, MI 49525,

USA

TRAVIS MANGIONE, Cornerstone University, 1001 E Beltline NE, Grand Rapids, MI 49525,

USA

ROBERT S. KEYS, Cornerstone University, 1001 E Beltline, NE, Grand Rapids, MI 49525,

USA

ABSTRACT In response to the decline of grassland birds and their habitat, the Pierce Cedar

Creek Institute has been working to restore portions of their property to prairie habitat. Obligate

grassland bird species, including the Henslow's sparrow (Ammodramus henslowii) and

grasshopper sparrow (Ammodramus savannarum), have avoided these grasslands despite a

decade of the prairie restoration. In the summer of 2016 we investigated the vegetation of

grasslands and restored prairies throughout Southwest Michigan to determine if vegetation

characteristics within these restored prairies are driving site selection. Our bird and vegetation

surveys found significant differences in vegetative density, litter depth, vegetative height and

cool/warm season mixes between restored prairies and other grasslands in regards to obligate

grassland birds. We found obligate grassland birds preferred a mean vertical density of 46.6 cm,

3.56 cm litter depth, 70.3 cm vegetation height, and 61.32% cool-season plant dominance. These

parameters significantly differ than what is found in restored prairies, which were nearly void of

obligate grassland birds. This information helps to inform the Institute’s management plans to

increase grassland bird biodiversity in their prairies.

KEY WORDS: biodiversity, cool-season plants, grasshopper sparrow, grassland birds,

Henslow's sparrow, Pierce Cedar Creek Institute, prairie management, prairie restoration,

Southwest Michigan, vegetation characteristics

Hindy, Mangione and Keys 2

INTRODUCTION

The decrease in grassland bird species over the last 30 years has put grasslands in the

conservation spotlight (Johnson and Igl 2001; Ribic and Sample 2001; Bakker et al. 2002;

Norment 2002; Herkert et al. 2003; Brennan and Kuvlesky Jr. 2005). Eighty percent of

grasslands in the United States have been converted to other uses such as development and

agricultural use (Rahmig et al. 2009). The State of Michigan has also seen 99% of its original

grasslands converted to other uses over the last one hundred years (Chapman and Brewer 2008;

Parker 2012). The Pierce Cedar Creek Institute (Institute) (42°32'07.0"N 85°18'06.7"W) has

been mitigating this loss by restoring 30.35 ha of tallgrass prairie and increasing the contiguous

prairie footprint to make their grasslands attractive for grassland birds. Remaining native

grasslands are in danger of natural plant succession (Norment 2002), thus increasing the patch

size of the Institute’s grasslands is a priority in slowing succession (Fletcher and Koford 2002;

Norment 2002).

The two target bird species of the Institute's restored prairie are the state endangered

Henslow’s sparrow (Ammodramus henslowii) and the state "species of special concern"

grasshopper sparrow (Ammodramus savannarum) (BirdLife International 2012; Howell 2015).

Surveys prior to the Institute's prairie expansion recorded only three sightings of Henslow’s

sparrow over the past six years (Oosterhouse et al. 2012; Cushman et al. 2013; eBird 2014).

Research completed last year at the Institute indicated no Henslow’s sparrows in the new

contiguous prairie environments (Lambert et al. 2015). In contrast, two other regional grassland

sites (Soya Conservation Reserve Program grassland and Gerald R Ford International Airport)

show healthy breeding population combinations of Henslow’s, grasshopper, savannah


(Passerculus sandwichensis), and/or vesper sparrows (Pooecetes gramineus), along with

bobolink (Dolichonyx oryzivorus) and eastern meadowlarks (Sturnella magna) (Lambert et al.

2015).

The disparity between these sites and the desire to make modifications at the Institute to

attract these species has prompted questions regarding occupation factors present in other sites.

Lambert et al. (2015) found cool season domestic fescue grasses (Festuca sp.) had the highest

correlation with grassland bird diversity over goldenrods (Solidago sp.) and big bluestem

(Andropogon gerardii) dominated grasslands (Lambert et al. 2015). Over time, big bluestem can

come to dominate in abundance and create a monoculture in restored prairies (Kindscher and

Tieszen 1998). This dominance of big bluestem could deter grassland birds from inhabiting

restored prairies (Lambert et al. 2015).

This led us to hypothesize the driving factor contributing to the absence of obligate grassland

birds at the Institute was the vegetative characteristics of the prairies. Grassland vegetation has

characteristics that affect grassland bird diversity, such as vertical density, litter depth, vegetative

height, and ground cover (Fletcher and Koford 2002; Rahmig et al. 2009). For instance, studies

have noted Henslow's sparrows prefer a high vertical density (Navarette-Tindall 2010), tall

vegetation (Herkert 1994), and a deep litter layer (Zimmerman 1988). Conversely, other studies

found that grasshopper sparrows prefer sparse, low vegetation (Jobin and Falardeau 2010; Ruth

2015). Aspects such as this make it difficult to manage for multiple species within the same

grassland. While the habitat components for Henslow's sparrows is similar in nature to the

grasslands at the Institute, Henslow’s sparrows have rarely been found in the tallgrass prairies on

the site. This structural component of grasslands will be a part of our investigation into the low

grassland bird biodiversity on the Institute property.


The vegetation at the Institute consists mainly of warm-season grasses and forbs (Lambert

et al. 2015). While required for a prairie ecosystem, it may indirectly affect the use by grassland

birds in this region (Lambert et al. 2015). Warm-season plants grow in mid-summer and are

potentially not suitable for the early migration of obligate grassland birds. Cool-season

herbaceous plants are beneficial because they grow earlier in the season and provide ample cover

and food for the grassland birds as they return from the wintering grounds (Navarette-Tindall

2010). Lambert et al. (2015) found the sites with the greatest grassland bird diversity consisted

of a combination of warm-season and cool-season plants, with more of the latter than the former.

This prompted us to consider if this was an important vegetative characteristic at the point of

migratory return. We matched sites attracting target species with randomly selected non-use sites

to determine if vegetative characteristics in the early season drive site selection. Regardless of

the vegetative characteristics, the success of a grassland is related to its ability to act as a source

site and not a sink for the target grassland species (McCoy et al. 2001).

Our primary objective is to build on Lambert et al. (2015) to ascertain what vegetative

characteristics in restored prairie grasslands act as attractors or detriments to the grassland bird

diversity of eight obligate grassland species.

Based on this objective we have hypothesized:

H1: the initial condition of vegetative factors at migratory arrival grasslands will determine

choice for breeding use amongst obligate grassland bird species.

H2: forb/grass height, litter depth, and vertical density will be determining factors in grassland

choice by target species.

H3: higher diversity of grass and forb species will result in higher diversity of obligate grassland

birds.


H4: obligate grassland birds will occur in grasslands that have greater coverage of cool-season

grasses and forbs than warm-season.

Developing a better understanding of the grassland characteristics in restored prairie

grasslands and those sought by grassland birds will help further the management techniques at

the Institute and other restored prairies in increasing grassland bird biodiversity.

METHOD

Study Sites

Grassland sites at 20 locations were surveyed in Barry, Kent and Kalamazoo Counties,

Michigan, USA 23 May- 19 July 2016. Grassland sites were subdivided into two categories

based on management practices and vegetative characteristics: restored prairie (RP) and mixed-

management grasslands (MM). Mixed-management grasslands are grasslands which have not

been restored and are generally fallow hay fields or maintained as grassland for other purposes.

They may use various methods of management including mowing, seeding, burning, or no

management whatsoever. Grassland sites ranged in size from 1 ha to 62 ha (Appendix A). Each

category of grassland included matched sites of similar size (Table 1).

Table 1. Number of grassland sites surveyed based on category and size range, 23 May – 19 July

2016, Barry, Kent and Kalamazoo Counties, Michigan, USA.

Grassland Category <10 ha 10-30 ha >30 ha

Restored Tallgrass Prairie 6 4 1

Mixed Management 3 4 2

Study Species

Our study focuses on eight species which are dependent on grasslands for breeding and

reproduction (obligate grassland species): Henslow’s sparrow, grasshopper sparrow, savannah

sparrow, vesper sparrow, dickcissel (Spiza americana), bobolink, eastern meadowlark and


upland sandpiper (Bartramia longicauda). We also collected data on species not fully dependent

on grasslands for nesting and reproduction (semi-obligate species): field sparrow (Spizella

pusilla), song sparrow (Melospiza melodia), and common yellowthroat (Geothlypis trichas).

Bird Survey

We conducted point count surveys of all obligate and semi-obligate grassland birds at

each site during the breeding season, 23 May – 20 June 2016 using a 10-minute, 50 m radius,

fixed point count method (Ralph et al. 1993). Surveys were conducted between sunrise and

10:00 AM; when breeding birds are most active. We recorded all target species seen or heard,

along with sex of individual (if identifiable). 100 x 100 m grids were layered over a digital

orthographic projection of each site using ArcGIS 10.4 (ESRI 2015), with each grassland cell

considered a potential point count sampling unit. We stratified sites into sections of 6-10

potential sampling units based on the sizes of the site and then randomized for point count visits

to cover the entire range of variability within each site. Sampling units were not repeated over

the survey period to ensure the most complete sampling of each site (Fletcher and Koford 2002).

Point count observations were inputted into ArcGIS 10.4 and analyzed with territory

buffers of each target species to negate pseudo-replication among sighted birds. Territory buffers

of birds overlapping at least 50% between point count sampling units were considered one

individual bird.

Habitat Measurements

Pre-arrival. Initial vegetation height, vertical density, and litter depth were made in early

May 2016 at point of initial migratory return at 13 point count locations known to have had

target species in the 2015 survey. These were paired with 13 point count sites with no target

species in the 2015 survey (Lambert et al. 2015).


Breeding Season. We measured vegetation type, percent cover, vertical density, vegetation

height, and litter depth at 35 point count sites containing obligate target species from our 2016

surveys. Each of these was paired with a random point count site containing no obligate target

species to test for vegetative effects between occupied sites and sites lacking obligate grassland

birds. Vegetation type and cover was measured using 0.25m2 Daubenmire frame (Rahmig et al.

2009) at four plots within each site: 1 at the center of the point-count area and 3 located at 0o,

120o, and 240o 30m from the center point (Fletcher and Koford 2002). Litter depth and

vegetation cover was measured in centimeters at each plot site, taking the average of the litter

depths in each corner of the frame (Rahmig et al. 2009). Vegetation height was defined as height

of tallest green vegetation measured in centimeters at each corner of the Daubenmire frame

(Fisher and Davis 2010). Plants within the Daubenmire frame were identified to the species

whenever possible, and defined by growing season. Cool-season vegetation was defined as

primarily growing during spring and fall seasons. Warm-season vegetation was defined as

primarily growing during the summer. Vertical density was determined by measuring visual

obstruction of grasses and forbs looking through a sighting pole 1 m from ground level and 4 m

from a Robel pole in each of the four cardinal directions (Fletcher and Koford 2002; Smith

2008).

Statistical Analysis

We modeled statistical analysis after similar studies on grassland birds conducted by

Fletcher and Koford (2002), Rahmig et al. (2009) and Thomas et al. (2010). Species richness

was defined as number of obligate grassland breeding species observed (Fletcher and Koford

2002). Due to a small sample size of vegetation characteristics examined during migratory

return, a non-parametric Wilcoxon Signed-Ranks test was used to determine differences between


sites with obligate grassland birds and sites without obligate grassland birds. Independent

sample T-tests were used to determine the differences between litter depth, vertical density,

vegetative height, and ground cover during breeding season. A multiple linear regression was

used to determine the most parsimonious model between Shannon diversity indices of vegetation

and obligate grassland birds (H'), with obligate grassland birds serving as the response variable.

Vegetative models between observed and random points were compared on a seasonal plant-type

basis using Chi-square to determine if specific seasonal plant types drive the selection of habitat

by species.

RESULTS

Survey results

Point count surveys showed obligate grassland birds had highest occurrences in mixed

management grasslands greater than 30 ha. Concurrently, semi-obligate grassland birds occurred

in high numbers in restored prairies at all grassland sizes. Mixed-management grasslands had

158.67% more individual obligate birds than restored prairie grasslands (Table 2 and 3). Obligate

grassland birds occurred in fields as small as 9 ha and as large as 62 ha.

Table 2. Number of obligate and semi-obligate grassland birds counted in 10-minute point counts

in grasslands based on grassland management practice and size differential. 23 May – 20 June

2016, Barry, Kent and Kalamazoo Counties, Michigan, USA. <10 ha 10-30 ha >30 ha

P3 O4 SO5 P O SO P O SO

RP1 31 1 94 48 0 139 59 2 150

MM2 25 8 19 80 101 125 107 367 37

1Restored Prairie 2Mixed Managed Grassland 3Point Count Sites 4Obligate Grassland Birds 5Semi-obligate Grassland Birds


Table 3. Number of each species recorded in point counts, number of grasslands they were found

in, and number of those birds occurring in restored prairies (RP) and mixed-management

grasslands (MM); 23 May – 20 June 2016, Barry, Kent, and Kalamazoo Counties, Michigan,

USA.

Species # Observed # Grasslands # of birds in RP # of birds in MM

HESP1 135 7 2 133

GRSP2 13 2 0 13

SAVS3 120 3 0 120

VESP4 1 1 1 0

DICK5 6 1 0 6

BOBO6 158 6 0 158

EAME7 44 5 0 44

UPSA8 2 1 0 2

FISP9 141 16 92 49

SOSP10 209 20 121 88

COYE11 271 18 193 78

1Henslow's sparrow 2grasshopper sparrow 3savannah sparrow 4vesper sparrow 5dickcissel 6bobolink 7Eastern meadowlark

8upland sandpiper 9field sparrow 10song sparrow 11common yellowthroat

Migratory vegetation differences

A Wilcoxon Signed-Ranks Test of 2016 migratory arrival vegetative data between 13

sites with obligate grassland birds and 13 sites without obligate grassland birds (based on 2015

point count survey) showed no significant difference in litter depth (Z = -1.745, p = 0.081),

vegetation height (Z = 0.075, p = 0.916), and vertical density (Z = -0.524 , p = 0.600).

Mid-Breeding Season Vegetation differences

Independent Samples T-tests showed significant differences in litter depth (cm),

vegetation height (cm) and vertical density (cm) between sites with and without obligate

grassland birds. Litter depth was 67.4% greater in sites without obligate grassland birds (M =

7.17 cm, SD = 2.904) than with obligate grassland birds (M = 3.56 cm, SD =1.941); T(68) =


6.119, p < 0.0001. Similarly, vegetation height was 18% greater in sites without obligate

grassland birds (M = 84.22 cm, SD = 14.793) than with them (M = 70.33 cm, SD = 17.801);

T(68) = 3.551, p = 0.001. Vertical density of grasslands was also 39.8% greater at sites without

obligate grassland birds (M = 69.74 cm, SD = 21.908) than it was at sites where they were

present (M = 46.61 cm, SD = 19.690); T(68) = 4.645, p < 0.0001.

An Independent Samples T-Test showed no significant differences in ground cover at

sites with obligate grassland birds (M = 3.08, SD = 0.632) and sites without obligate grassland

birds (M = 2.96, SD = 0.841); T(68) = -0.676, p = 0.502.

Vegetation preferences

Using an adjusted Braun-Blanquet cover-abundance scale (Ralph et al. 1993), we defined

dominance as the addition of this scale for species according to growing season. We found cool-

season vegetation occurred more frequently in sites with obligate grassland birds (n = 382), as

opposed to warm-season vegetation (n = 120). This was inversely projected by sites absent of

obligate grassland birds which had a higher frequency of warm-season plants (n = 224), as

opposed to cool-season plants (n =182) (Figure 1).

Percent coverage followed a similar pattern as occurrence of plant type in regards to

growing season and bird diversity. Sites with obligate grassland birds exhibited a higher percent

coverage of cool-season plants (61.32%) as opposed to warm-season plants (17.25%). The

opposite held true for sites absent of obligate grassland birds, with warm-season plants

dominating vegetation (58.61%) and cool-season plants consisting of a smaller percentage of

land cover (22.91%) (Table 4).

The percentage of grasses, forbs, and woody plants did not differ greatly between absent

and obligate sites. Obligate sites consisted of 42.23% grasses, 31.14% forbs, and 5.2% woody


plants, and absent sites consisted of 38.95% grasses, 40.64% forbs, and 1.93% woody plants

(Table 4). Further analysis of data showed that of the grasses found between obligate and absent

sites, obligate grassland birds preferred sites dominated by cool-season grasses (Figure 2).

Table 4. Percent coverage by different vegetation classifications using the Braun-Blanquet cover-

abundance scale within a Daubenmire frame from 1 July 2016 to 19 July 2016 in Barry,

Kalamazoo and Kent counties, Michigan, USA

Percent Coverages Absent Obligate

Warm Season Plant Cover 58.61% 17.25%

Cool Season Plant Cover 22.91% 61.32%

Grass Cover 38.95% 42.23%

Forb Cover 40.64% 31.14%

Woody Cover 1.93% 5.2%

Figure 1. Comparison of sites absent of obligate grassland birds vs. sites with obligate grassland

birds in regards to warm season vegetation and cool season vegetation dominance over all plots.

1 July – 19 July 2016, Barry, Kent and Kalamazoo Counties, Michigan, USA.


Figure 2. Percentage composition of warm-season and cool-season grasses at sites absent of

obligate grassland birds vs. sites with obligate grassland bird populations overall all survey

points. 1 July - 19 July 2016, Barry, Kent and Kalamazoo Counties, Michigan, USA.

Vegetation diversity and grassland bird diversity

Linear regression modeling showed only a weak correlation between grassland vegetation

diversity to bird diversity (R2 = 0.289) (Figure 3).

Figure 3. Linear regression of vegetation diversity to bird diversity of each grassland with

obligate grassland birds. 1 July- 19 July 2016, Barry, Kent and Kalamazoo Counties, Michigan,

USA.

-1

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1

2

3

2 2.2 2.4 2.6 2.8 3 3.2 3.4

Bir

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Vegetation Diversity


DISCUSSION

We had hypothesized that initial vegetative conditions at migratory return would be

different at sites with obligate grassland birds than sites not previously having them. Our results

indicated no statistical difference between the initial conditions of vegetation for site selection

during migratory return. Vegetation conditions during migratory return may not be a factor in

site selection for establishing territories. However, sample size may play a factor in these results

(N=13 for each variable).

We also hypothesized forb/grass height, litter depth, and vertical density would be

determining factors in grassland choice by target species. This hypothesis was supported by our

results. Obligate grassland birds preferred sites with a shorter mean vegetative height (70.33 cm),

a shallower mean litter depth (3.55 cm), and lower mean vertical density (46.61 cm), than sites

without grassland birds. Our results paralleled previous studies by Lambert et al. (2015), Winter

et al. (2005) and Skinner (1975) relating to habitat selection by obligate grassland bird species.

This could be a result of adaptations to new habitat, given the loss of prairie habitats in this

region over 100 years ago. Obligate grassland bird preferences may have shifted as increasing

grassland habitats were converted to agricultural and urban uses in Michigan and the United

States and less of their original habitat remained (Rahmig et al. 2009, Parker 2012). This could

also be a result of locational differences in surveys conducted.

We also hypothesized higher diversity of grass and forb species would result in higher

diversity of grassland birds. This hypothesis was not supported by the data. Many of our restored

prairie grasslands, other than those taken over by big bluestem, had high vegetative diversity.

The plant species richness though was not as important as the structure of the vegetation, which

was why they were void of obligate grassland birds (Bakker et al. 2002). Some of the grasslands


with high bird diversity (Soya East), did not have high vegetative diversity, and were composed

primarily of the dominant hayfield-type grasses.

Finally, we hypothesized that grassland birds would occur in grasslands having greater

coverage of cool-season grasses and forbs than warm-season. This hypothesis was supported by

our data. These results differ with Jaster et al. (2013) who found Henslow's sparrows did not

prefer cool-season over warm-season, but are consistent with McCoy et al. (2001) who found

Henslow's sparrows preferred grasslands dominated by cool season vegetation over warm season

vegetation. Our results suggest grasslands dominated by cool-season vegetation result in greater

abundance and higher diversity of obligate grassland bird species.

Our results also indicate obligate grassland birds are found in grasslands varying in size,

from 9 ha to 62 ha. This finding suggests that obligate grassland birds may not be dependent

upon grassland size for site selection. Earlier research indicated that while obligate grassland

birds can be found in smaller patch sizes, they exhibited higher densities in large grasslands

(Herkert 1998; Swanson 1998; Winter and Faaborg 1999; Dechant et al. 2001). Larger

grasslands in our study showed a higher diversity, as well as a greater populations, of obligate

grassland birds as would be expected with island biogeographic theory (MacArthur and Wilson

1967).

Restored prairie plantings in Michigan have not attracted obligate grassland birds despite

the good intentions of organizations such as the Institute. We did not expect to find even the

largest restored prairies virtually empty of obligate grasslands birds. If obligate grassland birds

are one of the main drivers for prairie restorations, then current restoration methods need to be

adapted to replicate the vegetative structure of sites with obligate grassland bird populations or


adjust management practices to better exemplify other Midwest prairie sites where obligate

grassland birds are present.

While obligate grassland birds can inhabit small grasslands (9-13 ha), they were more

abundant in extensive grasslands (Herkert 1998; Swanson 1998; Winter and Faaborg 1999;

Dechant et al. 2001). Therefore, removing additional fencerows to connect all of the prairies at

the Institute could be beneficial. In addition, reducing the impact of warm-season grasses,

specifically avoiding a big bluestem monoculture, by planting the prairies with fewer grasses and

more forbs would make restored prairies more similar to historic Michigan prairies (Grman et al.

2013).

Prescribed fire has been the management practice of choice for many Michigan

organizations managing restored prairies. Fire is a necessary component of the prairie ecosystem,

but it must be done little by little over many years (Schramm 1990). It is effective in reducing the

litter depth, but only in the first few years (Zimmerman 1988). Some obligate birds however,

avoid sites burned in the last 3 years (Cully and Michaels 2000). Since the Institute has not had

obligate birds, prescribed fire might not be enough for the prairies to be attractive to grassland

birds.

Another management practice that has been fairly common is mowing. Mowing is

usually done in the late summer after the birds have nested and fledged (NRCS 1999). This can

be efficient in controlling growth of unwanted plants and trees. Studies have suggested that

mowing is not a good substitute for fire, as it may cause negative results on plant productivity

(Schramm 1990). While it is not the most natural method of management, it has been the chosen

method of the Gerald R Ford International Airport, which has the highest grassland bird diversity

in Southwest Michigan.


The last popular management practice is rotational grazing. Grazing is allowing certain

ungulates to graze in the prairies. This creates a varied pattern of plant height in the grasslands

and can be a good control for unwanted plant growth. Certain ungulates, such as elk and bison,

only eat grasses and leave the forbs (Undersander et al. 2000), which makes them the best

choices for grazing over goats, horses, cows, and sheep. Grassland birds have been shown to

benefit from rotational grazing (Undersander et al. 2000).

All of these management techniques have been used throughout the Midwest. Each

management practice has various benefits and each has been shown to increase bird biodiversity.

Finding what best works for Southwest Michigan will likely require multiple management

practices. As of now, prescribed fire alone has not given the desired results, thus trying different

management techniques to inhibit warm-season plant dominance may have better results in

increasing not only obligate grassland bird populations, but in creating healthier prairie

ecosystems. Therefore, our research recommends that PCCI increases grassland size, reduce

warm-season grass dominance, and combine mowing with prescribed burning to provide more

suitable habitat for obligate grassland birds to thrive.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the financial support of the Willard G. and Jesse M.

Pierce Foundation and project support of the Pierce Cedar Creek Institute without which this

project would not have occurred. We would also like to thank C Scholten, K Strydhorst, and D

Proppe from Calvin College for their collaborative support on this project. Finally, we thank the

Michigan Audubon Society, Gerald R. Ford International Airport, Kalamazoo Nature Center,

and Barry County landowners G Cullers, B Olmstead, W Alward, J Soya, and A Jones for their

support and land access throughout this project.


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APPENDIX A

Grassland site locations (with GPS) surveyed from 23 May to 19 July, 2016, in Barry,

Kalamazoo and Kent Counties, Michigan USA.

Grassland Name Type Size (ha) County GPS

Cullers RP 1 Barry 42°33'33.7"N, 85°17'58.6"W Harris East RP 3 Kalamazoo 42°19'43.8"N, 85°40'07.6"W Harris North RP 4 Kalamazoo 42°19'54.0"N, 85°40'20.3"W Harris West RP 7 Kalamazoo 42°19'45.8"N, 85°40'18.9"W Olmstead East MM 7 Barry 42°33'1.62"N, 85°13'50.43"W

Olmstead North RP 7 Barry 42°32'58.69"N, 85°14'4.37"W

Alward RP 9 Barry 42°33'13.1"N, 85°17'43.7"W Jones MM 9 Barry 42°32'55.65"N, 85°18'22.98"W

GRR North MM 9 Kent 42°53'49.9"N, 85°31'13.7"W PCCI East RP 10 Barry 42°32'0.38"N, 85°18'4.89"W

PCCI North RP 11 Barry 42°32'30.91"N, 85°18'9.36"W

PCCI West RP 12 Barry 42°32'5.23"N, 85°18'18.12"W

Olmstead South MM 13 Barry 42°32'46.96"N, 85°13'58.67"W

Otis Farm RP 15 Barry 42°36'05.1"N, 85°23'20.4"W Olmstead Southeast MM 16 Barry 42°32'53.22"N, 85°13'43.85"W

GRR Mid MM 24 Kent 42°52'32.8"N, 85°31'14.8"W Soya West MM 27 Barry 42°32'5.13"N, 85°16'57.19"W

Soya East MM 46 Barry 42°32'1.34"N, 85°16'29.15"W

KNC Prairie RP 59 Barry 42°21'09.1"N, 85°35'11.3"W GRR South MM 61 Kent 42°51'33.50"N, 85°31'14.51"W