Birds Observed During Nesting Season at Jeffers Petroglyphs Historic Site, Cottonwood County, Minnesota

Bird Species Observed on Two Prairie Transects

Jeffers Petroglyphs Historic Site

Cottonwood County, Minnesota

June 22, 2019

Indicated singing (territorial) males of apparent nesting species were recorded on two transects/routes at the Jeffers Petroglyphs State Historic Site, Cottonwood County, Minnesota, on June 22, 2019.  Incidental observations were also made there on June 21, 2019.  Birds were recorded while walking slowly along the Prairie Trail loops of both the North and South loops at the site.  Jeffers consists of about 160 acres of prairie and inferences could be made about the density of singing males per 100 acres (or hectares) from these numbers.  There aren’t enough replications of the routes to provide valid data on densities.  Instead, this information should be used as an indicator of relative abundance or frequency on both prairie trails and for the entire site.  Collection of more valid information on densities would require a more intense technique like the Williamson Spot-Mapping method or some similar effort.  These data can be used as a benchmark to compare future relative frequency if a competent observer walks the trails and records the number of singing males encountered.

I wish I could have seen this area before it was subdued by European settlers

Methods

I recorded all singing males heard or seen from any distance along the two routes followed but attempted to record birds that I was certain were inside the boundaries of the property.  I also recorded birds flying over the property that obviously were not nesting there (Turkey Vulture, Great Blue Heron, Rock Dove, and both species of Swallow).  They were recorded to add to the species list for the site but should not be considered nesting on the property.  Before arriving at Jeffers, I stopped at a small stream crossing just south of the Sioux Quartzite quarry about 0.5 miles from the site.  There I heard and saw two other species, Black-headed Grosbeak (Pheucticus melanocephalus) and Great Crested Flycatcher (Myiarchus crinitus) that are riparian-dependent in this part of Minnesota.  There is no suitable habitat for them on the Jeffers site; they are included here simply for anecdotal purposes because they are near the site.

Results

Twenty-six (26) bird species were recorded on or from the prairie study area on June 22, 2019.  Observations were conducted from 0930 h to 1212 h under cloudy skies with a light wind.  The temperature ranged from 63 to 68 degrees.  The north transect was covered in a clockwise pattern beginning at the main trail to the petroglyphs then proceeding northwest, east along the north boundary then south and southwest to the starting point.  I deviated from the transect route at one point to check some shrubs near a rock outcrop where an obvious small amphitheater was built.  The south transect was covered in a counterclockwise pattern beginning near the display of Native American lodges, then south and southeast along the south boundary.  From there I traveled northeast to near the east boundary, then continued west to the starting point. 

Native prairie evolved under a regime of fire and the prairie at Jeffers is managed with fire.  Smooth brome (shown here) is one of very few invasive plants occurring in the native prairie, indicative of the success of the fire management program at the site.  With luck there will be a small herd of American Bison roaming this prairie in a few years - I hope I live long enough to see them back where they are supposed to live.

Discussion

Despite the small size of the site there are two prairies present.  The “North Prairie” is made up of robust native grasses that have long been established. The plant community consists mainly of native prairie species that are common to remnant prairies of southwestern Minnesota.  The “South Prairie” is a restored prairie populated with grasses and forbs that originated from seeds obtained in Nebraska.  Forbs are not nearly as obvious (at least at this time of year) in the South Prairie as they are in the North Prairie.  This might be an artifact of the origin of those plant species in a drier less forb-rich environment in Nebraska.

Portions of the North Prairie benefitted from a controlled burn in April 2019 and the robustness of the regenerating grasses was obvious in the burned area.  Conditions were not conducive for burning the South Prairie in the spring of 2019 and at present there is an abundance of fuel present.  Given the proper wind direction, heat, and humidity, a fire on the entire south 80 acres of the site would likely produce a robust growth of regenerating grasses.

I was pleasantly surprised to witness so few invasive plant species present on both prairies.  One obvious invasive, Smooth Brome (Bromus inermis) is present throughout the site but especially along the trails leading through the prairie.  Intense fires in spring and again in fall along this trail might be beneficial in helping to control distribution and abundance of Bromus on this site.

It is my intention to return to this prairie at least annually to record the relative abundance of nesting species on this site.  As time and funds allow, I might return at other times of the year to record migrants.   Ideally it would be useful to re-activate my Master Bander permit and establish a mist netting station in the grassland especially in fall migration to obtain a better understanding of the abundance and diversity of migrant species, especially sparrows.

And mom has done a very good job of landscaping here

Management Suggestions:

Nothing can be written by an alumnus of the Northern Prairie Wildlife Research Center without some recommendations on managing study areas, and Jeffers Petroglyphs is no different.

1)  I highly recommend that visitors be required to immerse the soles of their foot ware in some type of antiseptic that will 1) remove the seeds of potential invasive plant species or 2) kill those seeds before they can be brought onto the prairie by unsuspecting yet well-intentioned visitors.  The near-absence of invasive species (with the obvious exception of Bromus inermis) suggests that managers at the site are ahead of the game on keeping Jeffers relatively free of invasive species.  Sterilizing foot ware will help enormously in this area.  

2) To help educate the public, if a foot ware sterilization effort is implemented it should be accompanied by an informational diorama or something similar to explain why visitors are being asked to cleanse their feet.  This may be beneficial in assisting visitors to think about what they might be carrying on their feet in other areas.

3)  The south boundary of the site is adjacent to an active agricultural field.  During my visit there I noticed several large hay bales on the neighbor’s land indicating that the land was actively used for producing agricultural crops.  It would be useful to establish a fire break along that south boundary to impede the natural movement of grasses growing in the agricultural field onto the restored prairie at the south end of Jeffers. Maintaining a similar fire break along the east boundary of the property would help to reduce the movement of invasive species from the adjacent agricultural pasture on that side of the property.   Lacking the necessary equipment to establish firebreaks on those two sides of the property, I would suggest contacting the US Fish and Wildlife Service Wetland Management District office in Windom, Minnesota, to work out a cooperative agreement where the Service could loan its equipment to help with the effort.  The Service manages several Waterfowl Production Areas in nearby areas of Cottonwood County, so equipment should be readily available.

"Native" Prairie on this map shows the general location of the "North Transect".  The area called "Restored Prairie" is the "South Transect"   Image by Dan Bauer

4)  Burn the prairie every second or third year at a minimum.  Prairie evolved under a regime of fire and my guess is that when Native Americans were visiting the Petroglyphs more than 1000 years ago there were regular fires on this prairie.  Perhaps the best strategy would be to burn the south 80 acres one year and the north 80 the next, then let the prairie lie idle for two years before burning again..  Ideally, to enhance diversity of prairie plants I would burn one 80 acres in the spring and the other in the fall on an alternating schedule.

5) Contract with the Minnesota Department of Natural Resources or a similar entity to establish plant diversity and abundance transects on both the north and south 80-acre parcels of the Jeffers property. These data will prove invaluable over time as an aid to assessing habitat changes and grassland management efficacy especially under a fire management scenario.  These data could also be coupled with future bird population census work to assess how grassland management is affecting bird diversity and abundance.

6) Consider re-establishing Greater Prairie-Chickens on this site.   No doubt before European settlers harnessed and subdued the prairie Greater Prairie-Chickens were the dominant Phasianid here.  Now that role is occupied by the introduced and invasive Ring-necked Pheasant.  There are several very obvious areas on the north and south prairies where I could imagine Greater Prairie-Chickens establishing booming grounds in the spring.  There is an abundance of agricultural land in the area that could provide a food source for Prairie-Chickens.  There is also an abundance of agricultural land that has been set aside in the Conservation Reserve Program (CRP) that can provide additional habitat for Prairie-Chickens.  I suggest that management of Jeffers Petroglyphs develop a partnership with The Nature Conservancy (which owns a number of preserves in the region) and the Minnesota Department of Natural Resources (which has several state wildlife management areas in the region) to cooperatively release and hopefully re-establish Prairie-Chickens on the site.

Bobolink spends its summer in North America and our winter in the Patagonia region of Argentina, Paraguay and Brazil.  During nesting season they are a conspicuous and vociferous component of the grassland bird community.   This Bobolink was photographed by Dan Bauer at Jeffers on June 21, 2019

Relative Abundance of Singing Male Birds on Two Transects

Jeffers Petroglyphs, Cottonwood County Minnesota

(Birds present but presumed not to be nesting on the site are highlighted in the “Notes” section)

Species	Number of Males on North Prairie Transect	Number of Males on South Prairie Transect	Notes
Ring-necked Pheasant	4	3
Rock Dove		3	Fly over
Mourning Dove		1
Killdeer		1
Great Blue Heron		1	Fly over
Turkey Vulture			Flyover on June 21
Eastern Kingbird		1
Bank Swallow	1	1	Flyover
Barn Swallow	6		Flyover
House Wren		1
Eastern Bluebird	1
American Robin		1
Brown Thrasher	2
American Goldfinch	4	1
Grasshopper Sparrow	6	9
Clay-colored Sparrow	1	3
Field Sparrow	1
LeConte’s Sparrow	3	4
Henslow’s Sparrow	1	1
Bobolink	3	6
Western Meadowlark	3	2
Brown-headed Cowbird	3	3
Common Yellowthroat	3	5
Yellow Warbler	1
Indigo Bunting	1
Dickcissel	25	26

  

Species Accounts

Ring-necked Pheasant (Phasianus colchicus) Seven crowing males were heard on the site of which two were flushed.  No females were observed suggesting they were incubating eggs or brooding hatched chicks. Although an invasive species, Ring-necked Pheasant is a popular game bird for hunters and will never be eliminated from the landscape as long as hunting licenses can be sold.  In prairie regions this species generally spends the winter in wetland vegetation.  There being no wetlands on the property I would be interested in learning where this species spends the winter.

Rock Dove (Columba livia) Three birds flew over me as a I walked the south transect.  Several nearby farmsteads were the likely roosting and nesting areas for this invasive species.

Mourning Dove (Zenaida macroura) One singing male was heard and seen on the fence along the southeast boundary of the property.  Mourning dove is known to nest on the ground in areas where trees and shrubs are lacking.  In all likelihood this bird nested in a nearby wooded area on an adjacent property and was occupying Jeffers as part of its territory.

Killdeer (Charadrius vociferous) A single, vociferous, Killdeer was flushed from prairie grasses along the south transect.  Another Killdeer, likely the same bird, was seen later that day on the exposed rocks of the petroglyphs.

Great Blue Heron (Ardea herodias) Single birds (the same bird?) were seen flying over Jeffers on June 21 and again on June 22.  Both were flying in a northerly direction. There being absolutely no suitable nesting or foraging habitat for this species on the property these were incidental observation and should not be used to suggest this is a regular part of the avifauna of the site.

Turkey Vulture (Cathartes aura) See comment above for Great Blue Heron.

[Great Crested Flycatcher (Myiarchus crinitus) This species was NOT on the Jeffers property but instead in a riparian area along a stream about 0.5 miles south of the site.  I include it here simply for anecdotal purposes because of its proximity to the site.  It should not be considered a component of the Jeffers avifauna.]

Eastern Kingbird (Tyrannus tyrannus) One highly-agitated male Eastern Kingbird was heard and seen along the eastern boundary fence of the property.  The presence of several shrubby trees there likely provided a platform for nests but I did not take the time to investigate.

Bank Swallow (Riparia riparia) Single Bank Swallows were observed foraging with Barn Swallows as both species flew over the north transect and a single Bank Swallow was observed foraging over the south transect.  Road cuts exist in the area that could provide nesting habitat for this species but not so on the Jeffers property.  Instead this species and Barn Swallow use Jeffers as foraging habitat and should therefore be counted as part of the avifauna.

Barn Swallow (Hirundo rustica) Six Barn Swallows were observed foraging over the north transect.  Suitable nesting habitat platforms exist in the area including the visitor center building for the Jeffers Petroglyphs. 

House Wren (Troglodytes aedon) One singing male was heard in the woody vegetation along the boundary fence on the east side edge of the property.

Eastern Bluebird (Sialia sialis) One male was heard and then seen singing from the roof of a bluebird house established near the north transect trail.  Given the time of year and the presence of territorial singing I assumed there was a female with eggs or young in the nest box but did not open it to investigate.

American Robin (Turdus migratorius) An agitated male was heard doing its “clucking” call note from the fence line at the east edge of the property. Most likely this species was nesting in a wooded draw east of the boundary fence and used the fence for a song perch at the boundary of its territory.

Brown Thrasher (Toxostoma rufum) Two adults were observed along the north transect; one was flushed from the prairie vegetation and the other flew in to be with it.  This species commonly nests in brushy areas and as growths of Western Snowberry (Symphoricarpus occidentalis) become established on the prairie it is more likely that Brown Thrasher will be found nesting on the Jeffers property. 

American Goldfinch (Spinus tristis) Four males were recorded along the north transect and a single male on the south transect.  American Goldfinch is primarily associated with woody vegetation for nesting habitat so I doubt they were nesting on the Jeffers property.  They are well known for feeding the seeds of thistles to their newly hatched young, so more likely they were using the property as foraging habitat to feed young in nests in nearby woody vegetation. 

Grasshopper Sparrow (Ammodramus savanarum) An indicator of lightly grazed or moderately grazed native prairie, Grasshopper Sparrow occurred in numbers expected for the vegetation present.  Fifteen (15) singing males on 160 acres of prairie averaged about 9.3 pairs per hundred acres (a formerly common way of expressing density). 

Clay-colored Sparrow (Spizella pallida) An obligate prairie species, Clay-colored Sparrow is found most commonly in and near growths of Symphoricarpus occidentalis.  In North Dakota they occur as a nesting species in very large numbers in Western Snowberry-dominated prairie. I recorded one singing male on the north transect where Symphoricarpus is scarce.  Three singing males (including one that was highly responsive to a playback of its voice) were found on the south transect where Symphoricarpus is more common.  Symphoricarpus is not easily controlled by regular burning and can expand in area if burned too frequently.  About the only way of controlling it is to develop extremely hot fires.  Care should be taken during controlled burns of the Jeffers property to avoid burning Symphoricarpus to reduce the likelihood of its expansion across the grassland.  Allowing it to expand will help the Clay-colored Sparrow numbers but could also lead to a reduction in the variety of native plant species present.

Field Sparrow (Spizella pusilla) This is a species of retired fields that have been invaded by moderate growths of woody vegetation. The single bird I heard singing was near a growth of chokecherry (I think) near the northwest corner of the Jeffers property.  This was adequate habitat for Field Sparrow nesting although I did not find a nest.

LeConte’s Sparrow (Ammospiza leconteii) This is one of the most characteristic species of wet “swales” in native grasslands. They are highly secretive and their voice is among the most difficult to hear of any North American bird.  It sounds like its saying “Chick – eeeeeezee” and rarely sings from an exposed perch making them difficult to detect.  Their song is in the range of 10,000 cycles per minute and most humans hear in the 8,000 or 9,000 cycle range. I heard or saw three singing males on the north transect and four singing males on the south transect.  This is an exceptional number of LeConte’s Sparrows for an upland prairie (more are likely to be found in sedge-dominated palustrine emergent wetlands and other “low” prairie).  Each singing male I observed at Jeffers was found in low wet prairie vegetation.  Although well within the migration route of this species, the singing males at Jeffers are at the southern limit of their usual nesting range.  Surveys should be conducted to determine if LeConte’s Sparrow is present in similar habitats in adjacent areas.  They are well-known for having occupied Conservation Reserve Program lands that were protected from agriculture in North Dakota and South Dakota.  Given the abundance of CRP land in Cottonwood and adjacent counties of Minnesota, there might be an outlier nesting population of LeConte’s Sparrow that had not been discovered previously.  The presence or absence of this unique species should be considered an indicator of habitat quality at Jeffers.

Henslow’s Sparrow (Centronyx henslowii) A characteristic species of rank growths of ungrazed or lightly grazed prairie, the presence of Henslow’s Sparrow at Jeffers indicates a species near the northern limit of its nesting range.  Single singing males were found on both the north and the south transects.  Given the difficulty of detecting this species coupled with even mild wind, there likely were more Henslow’s Sparrows present than the two I encountered. 

Like LeConte’s Sparrow, this species has an extremely high-frequency voice and is quite difficult to hear.  Its voice sounds like its saying “sllllick” and is usually produced from inside grassland vegetation rather than from an exposed perch.  Curiously I have found them much more commonly in winter in places like wire grass openings in pine forests in the Panhandle of Florida than I have throughout their nesting range. This is another species that should be considered an indicator of habitat quality at Jeffers.

Bobolink (Dolichonyz oryzivorus) A species obligate to grasslands and hay fields, Bobolink has been historically difficult to accurately map using conventional nesting species mapping methods.  The three males recorded on the north transect and six on the south transect should be considered minimums.  Also, because June 22 is near the end of the nesting cycle for this species there may be some males that have already ceased to display or defend a territory.  Rarely have I found a singing male Bobolink in any of the prairie states after July 1 and never have I found them singing after July 5.  There were twice as many singing males on the south transect as on the north which may be a reflection of the species diversity of prairie plants on the south transect where there were more low “swale” areas than on the drier upland of the north transect.  Data on plant species abundance on the two transects would be useful in understanding differences in the apparent abundance of Bobolinks at Jeffers.

Western Meadowlark (Sturnella neglecta) Three singing males were heard and seen on the north transect and two on the south transect.  This formerly abundant grassland species, indicative of the western prairie, has suffered sharp population declines in the last twenty-five years.  I think much of the change in population can be related to the extensive conversion of native grassland and idle fields to corn and soybean production as the nation has strived to increase its biofuel capacity.  During three days of traveling in southwestern Minnesota, I saw or heard five Western Meadowlarks. All five of them were on Jeffers Petroglyphs – I did not see another Western Meadowlark anywhere else.   It’s a sad commentary on the status of the human environment when a species as common as Western Meadowlark once was, is now the exception rather than the rule.

Brown-headed Cowbird (Molothrus ater) Three males of this well-known nest parasite were found on the north transect and three more on the south transect.

Common Yellowthroat (Geothlypis trichas) A characteristic species of wet swales in native prairie I recorded three males on the north transect and five on the south transect.  This distribution seems to mirror the habitats with more wet prairie areas on the south transect and fewer on the drier north side.

Yellow Warbler (Setophaga petechia) A single singing male on the north transect was rather surprising because of the paucity of suitable Yellow Warbler habitat.  I would have expected this species more commonly in the wetter prairie of the south transect but found none there.  Perhaps this was an artifact of the nesting cycle of this species (near the end of it) rather than indicative of low numbers.

Indigo Bunting (Passerina cyanea) A singing male was heard and seen on the barbed wire fence along the north border of the property.  Other than the chokecherry growth in the northwest corner of the property or the woody vegetation along the eastern border there really is no suitable nesting habitat for this species at Jeffers.   It’s a part of the avifauna of the site but should not be considered a nesting species at this time.

[Black-headed Grosbeak (Pheucticus melanocephalus) As I approached the Jeffers site on June 22, 2019, I heard a Black-headed Grosbeak singing from riparian forest along a small stream about 0.5 miles south of the Jeffers entrance.  I stopped my vehicle on the bridge and listened to and watched this bird for about 10 minutes before continuing on to the site.   Its presence in this list should not be construed as indicating that Black-headed Grosbeak is a part of the Jeffers avifauna.  It is not. This species is included here because of its presence near the site and because it is generally rare in any part of western Minnesota.]

Dickcissel is by far the most numerous nesting species at Jeffers.  My major professor once described their voice as saying "Dick-sis-cha-cha-cha."   There are other variations but Steve's interpretation is the most accurate.  This vociferous Dickcissesl was photographed at Jeffers by Dan Bauer on June 21, 2019

Dickcissel (Spiza americana) Fifty-one (51) singing males were heard and seen on the two transects; 25 on the north transect and 26 on the south.  Far and away this makes Dickcissel the most abundant breeding bird at the Jeffers Petroglyphs Historic Site.  I found this species in other areas near Jeffers but not nearly in the abundance I found them on the site.  Most likely that was an indication of habitat presence, abundance and quality at Jeffers compared to remnant patches of grassland elsewhere.  For future management of habitats at Jeffers, Dickcissel should be considered the “Keystone” species against which changes should be compared.  Its numbers should be monitored closely to detect changes in how the species responds to management practices because it occupies all types of prairie vegetation on the site; upland and lowland prairie, dry and wet prairie, prairie with Western Snowberry and other shrubs and prairie without it.  The number of indicated breeding males here is on par with or perhaps slightly higher than densities I recorded in the early 1980s along the Platte River in Nebraska near the epicenter of the species nesting range in the prairie biome.