Grassland Habitat – A “Sensitive” Subject

Grassland birds are naturally adapted to native grasslands and prairie ecosystems throughout much of North America. While these are of the highest quality and “ideal” nesting habitats, they are now extremely rare and are fading quickly. As our grasslands fade, our resident bird species are forced to overcome and adapt. Nowadays, surrogate grasslands (hayfields, small grain farms, and fallow pastures) provide most of the important nesting habitat for our grassland-nesting birds. Strip habitats (utility right of ways, highway corridors, and field borders) that are maintained in an early successional state also offer valuable nesting and foraging habitats for several species.

Grassland birds rely upon herbaceous cover for natural foraging and nesting behavior. There are many nuances to the individual cover requirements amongst the different species. Some species are area-sensitive and require vast acreages of unbroken grassland habitat for nesting. Others are edge-sensitive, and shy away from fragmented landscapes to which they perceive as threats to them and their nests. As I have touched on in previous posts, the steps that we take as land practitioners that are meant to invite some species can be deterrents to others. What I hope to provide here is a CliffsNotes version of a much broader and highly complicated subject. Who would have thought that grass could be so dense (pun intended)?

Variables to Consider When Developing a Plan

Ask any neighborhood “Randy” who spends hundreds of dollars annually maintaining his chemically laden green turf, and you quickly find out that not all “grass” is created equal. This also applies to native and non-native grasses. The density and height, as well as surrounding land usages all influence the assemblage of birds that occur within a given area. Generally speaking, large, undisturbed plots of grassland habitat is more desirable and provides the most diverse grouping of grassland bird species. The expansive area allows birds to fulfill most of their courtship, nesting, brood-rearing, feeding, and leisure behavior with the added security requirements they prefer during nesting season. In addition, the larger habitat will also provide winter and migratory cover for many species.

Adequate cover of undisturbed grassland is among the greatest factors affecting grassland bird populations, and the continued loss and conversion of grassland breeding and nesting habitat remains the largest threat to the future of many of our grassland birds. Preserving existing and properly designing new grassland communities will help to maintain current species that are in decline. With proper management, local grassland bird populations will increase, and populations of other wildlife species will benefit from these same habitats.

Since hundreds or thousands of fallow acres aren’t lying in wait, it is up to us to think outside of the box and look for ways to improvise and work with what we do have available. Like pocket prairies for pollinators, the same approach can be taken with several of our grassland and early successional bird species.

Small Victories – Winning with “Edge-Sensitive” Species

As we have already established, most grassland species prefer large acreages of unfragmented habitat. Fragmentation in respect to land use is defined as the existence of a number of spatially separate plots of land which are managed singly. Typically, these smaller, isolated plots with heavily wooded edges have limited potential to support grassland birds. Interspersion (diversify in intervals) of various types of grasslands will maximize habitat quality for some species, however, interspersion of grassland habitat with woody vegetation or other land usage that would fragment the area can be detrimental to others.

Edge-sensitive grassland birds are those with the lowest tolerance for fragmented habitats and are typically grassland dependent when it comes to nesting behavior. When grasslands are fragmented, many grassland birds are subjected to nest predation from crows, blue jays, skunks, raccoons, opossums, foxes, and you guessed it, domestic cats.

Grassland birds that are edge-sensitive include the Upland Sandpiper (Bartramia longicauda), Bobolink (Dolichonyx oryzivorus), and Savannah (Passerculus sandwichensis) and Henslow’s (Centronyx henslowii) sparrows. The Eastern Meadowlark (Sturnella magna) and Grasshopper Sparrow (Ammodramus savannarumare) are moderately sensitive to habitat fragmentation. Grassland birds that are tolerant to an abundance of edge include the Northern Bobwhite (Colinus virginianus), Red-winged Blackbird (Agelaius phoeniceus), American Goldfinch (Spinus tristis), Vesper (Pooecetes gramineus), Field (Spizella pusilla), and Song (Melospiza melodia) sparrows, Dickcissel (Spiza americana), and Common Yellowthroat (Geothlypis trichas).

On landscapes where intensive row crop agriculture is the dominant land use, we can design strip habitats which are extremely important not only for grassland birds but for other wildlife as well. Grassland bird assemblages will vary with the physical habitat structure and seasonal disturbance patterns (i.e., crop planting & harvesting).

Size Matters – “Area-Sensitive” Species

Many “area-sensitive” grassland bird species require a certain amount of habitat to be present, usually in contiguous patches or unbroken blocks, before individuals will use a given site. Estimates of the minimum size of suitable nesting and breeding habitat required to support breeding populations of grassland birds vary greatly amongst species. If your goal is to support a wide array of grassland-nesting bird species within a given area, then contiguous grassland blocks of at least 500 acres will provide the greatest potential. However, smaller grassland blocks provide viable habitat patches for many grassland bird species. A general rule may be to maximize the size and interconnectedness of grassland habitat patches available, while conducting management actions that maximize the habitat quality within the smaller patches.

Area-sensitive species prefer treeless areas because trees provide shelter for predators. A familiar nemesis of the suburbs, the Brown-headed Cowbird (Molothrus ater) is also common in the countryside, parasitizing nests along wooded edges. Grassland birds that nest in larger blocks of grasslands that are at greater distances from trees see a higher percentage of fledglings take wing. Some area-sensitive species are obligate and depend upon certain plants to successfully function within a given grassland ecosystem.

To confuse the matter even further, the total area requirements vary from species to species and can also vary amongst geographical regions and the landscapes characteristics. For example, the size of habitat patches needed to attract individuals of a given species may be smaller in landscapes that contain a larger amount of grassland and open habitats nearby. 

Management Considerations

When possible, it’s beneficial to take a community or overall landscape approach to your designing, implementation, and management plans. If you own a small grassland, it helps to determine what the surrounding landscapes look like. If other grasslands or agricultural areas are present, then it may be feasible for you to manage for grassland birds despite having smaller acreage to work with. However, if your grassland is surrounded by forest, you may want to reconsider other goals.

 The following guidelines will not necessarily guarantee the presence or absence of certain species. Restoring and enhancing existing grasslands, and reducing fragmentation are hands down the best management options for grassland birds. Whenever you increase the size of a grassland, you increase the likelihood that grassland birds will benefit.

 Some things to consider when managing for grassland birds within your landscape:

 -          To manage for edge-sensitive species, you will need a minimum of 20 acres. Moderately sensitive species need between 10 and 20 acres, and tolerant species need less than 10 acres. These estimates are the minimum amounts these species need to survive. Again, the larger the grassland, the better.

 -          Avoid fragmenting existing grassland areas. If hiking trails are to be developed, restrict activities to the edges of the area. Avoid maintaining hedgerows that may serve as predator perches.

 -          If large tracts of grassland restorations are not possible, establish several patches. Try to incorporate adjacent grassy habitats such as pastures, hayfields, and grassy waterways as connections between the grassland patches or as non-wooded, open edges.

-          Maintain succession in its earliest stages by managing for grasses and sparse shrubs. Manipulations such as burning, and mowing are required to maintain grass productivity typically within three-to-five-year intervals.

 -          Manipulate your grasslands in 1/3 to 1/4 annual rotations. If several fields are maintained, it is better to manipulate one entire field, rather than a portion of each field per rotation. This will reduce fragmentation of your grasslands. However, if you have only one field, do not manipulate the entire field at once as it will displace the grassland birds. If possible, allow some sections to lie idle each year.

 -          Use prescribed burns to increase the productivity of warm season grasses. Conduct burns in early spring (March or April) or late fall (October or November).

 -          Mow grasslands and hayfields between July 15 and August 31. This will reduce the chance of destroying bird nests and discourages the invasion of problem grass species that move in after late season mowing. Cutting height should be about 6 inches.

 -          If you use the grassland for grazing, permit only light activity by livestock, and leave some areas un-grazed by utilizing rotational grazing practices. Do not graze below 6 inches. Moderate grazing may actually benefit additional wildlife species.

 -          Plant or maintain several types of grasslands in your area. A mosaic of tall and short grass fields will provide habitat diversity. If planting only one area, a mixture of warm season grasses and forbs is best. Cool season grasses mixed with legumes is another option.

 -          Create 100 ft. shrub buffers next to forest edges and human habitations to reduce the harsh edge. An alternative to planting shrubs along the edge of a forest is to allow the fire to burn slowly into the woods so as to create a "feathered" edge. Local fire authorities should always be contacted prior to a burn to discuss permits and/or restrictions.

 -          Chemical treatments of grasslands can also be used to control woody plants. Herbicides can be used to control any type of undesirable plants in your grassland, from woody plants to grasses and weeds. Correct application is important. Damage to non-target vegetation or wildlife is possible if you do not follow the labels instructions. Reducing or eliminating the use of insecticides will provide more valuable insect food for birds.

Just Do Something!

"When some remote ancestor of ours invented the shovel, he became a giver – He could plant a tree. When the axe was invented, he became a taker – He could chop it down. Whoever owns land has thus assumed, whether he knows it or not, the divine functions of creating and destroying plants."

-Aldo Leopold

As most of us have started to settle back into some semblance of “normalcy”, we are still within the throes of a worldwide pandemic. Government shut downs and social isolation have spawned record unemployment, political disconnect, civil unrest, and our ever-more-present-with-each-passing-year-friend global warming. When all hope seems lost, we as conservationist and land managers MUST dust off our boots, get back out there, and carry on with the work.

A Time When No Matter How You Choose, You Are Certain to Offend Someone

A reasonable person would assume that when you utilize your own time, money and resources to do something, ANYTHING for the environment, it would be warmly received by all, correct? Well, I hate to be the bearer of bad news, but this is no longer so Chappies and Chappettes! I recently had a conversation with the Senior Project Director of a major organization here in the US. It wasn’t until I had this conversation that I truly understood the gravity of the situation. I had pitched to him an upcoming “statement tee” that I planned to release and offered to include their organization on the campaign. For those of you that are not aware, a statement tee is a t-shirt that carries a bold statement on the front. Its intent is to stand out and deliver a message about something that you support. The campaign required no work or capital from them aside from lending their logo to the design. In return, a portion of all proceeds would be donated to them for their participation. We have done this in the past with other organizations and although our contribution doesn’t amount to anything that would make or break a company, every little bit helps right?

The idea I pitched focused on a certain demographic within their industry. A group of people that have been overlooked so to speak and haven’t received the proper recognition that they deserve. It is also a growing demographic that is performing exciting work for both science and the industry. My idea was met with caution and concern. Although being supportive of the idea on a personal level, he was concerned that if they backed this campaign, they would endure backlash from the other sector of their industry that wasn’t included. Despite not agreeing with his assessment initially, after pondering it for a bit, I couldn’t dispute his concerns seeing as to the current state of the world and the cancel culture that we now reside in.

It’s All Gone to The Birds

The hew of the European ax resulted in grassland bird species expanding their range into the midwestern and eastern states of North America during the late 1800s as forests were cleared for early, agrarian endeavors. Horned Larks (Eremophila alpestris) spread eastward from Illinois and Wisconsin beginning in the 1870s, and had reached the New England states by 1891. Other species that expanded their range eastward included the Western Meadowlark (Sturnella neglecta) and Lark Sparrow (Chondestes grammacus).

Showing up to the party fashionably late, the Henslow's Sparrow (Centronyx henslowii), also expanded its range; however, its population boom coincided with the period of farm abandonment in the early 1900’s as these same settlers expanded further west. Grassland birds like the Upland Sandpiper (Bartramia longicauda), Grasshopper Sparrow (Ammodramus savannarum), Savannah Sparrow (Passerculus sandwichensis), Eastern Meadowlark (Sturnella magna), and Bobolink (Dolichonyx oryzivorous), were likely already present in the Northeast prior to the large-scale forest clearing that had prompted the arrival of the aforementioned species.

From this data, it can be postulated that some forest bird species were without a doubt displaced when the forests were cleared. This displacement resulted in habitation by several new grassland species which after several years of farms being abandoned, were forced to seek refuge elsewhere as early successional species moved into the developing, scrubby habitat. Do you see a pattern?

Choose Wisely or Else!

So, from a conservation perspective, which direction should we go and which species should we target as we reshape and manage our landscapes? It has been suggested that the ideal habitat might be a landscape with scattered, small openings such as those that were created by native peoples. Another target could be 1966, when the United States Fish & Wildlife Service (USFWS) began the Breeding Bird Survey (BBS). Data from the BBS could be used to target specific grassland bird populations and implement management practices that cater to the species with the most rapid declines. For example, BBS data for Savannah Sparrows and Eastern Meadowlarks, show consistent, region-wide declines in the Northeast from 1966-1996. Similar trends for other species are the basis for the concern for grassland birds in regions with continued declines. If you support this approach, then you would de-emphasize late-successional forest species, which are already present, and focus your efforts on grassland bird recovery.

A case in point is the Bobolink, which since 1966 is declining at rates approaching 2% every year throughout their entire North American breeding range. In the Northeast, per BBS data, Bobolinks are most abundant in the St. Lawrence River Plain; which supports up to 17% of the world's population of Bobolinks. Even though the St. Lawrence River Plain was dominated by deciduous hardwood forests in pre-Columbian times, cultivation during the last 200 years has created a vast agricultural grassland in which climate and poor drainage have enhanced the value of the region to grassland birds such as the Bobolink and Henslow's Sparrow. In this case, a rational argument could be made for a management target date set in the late twentieth century, with an emphasis on enhancing grassland habitat. That approach is being undertaken by the USFWS in its St. Lawrence Wetlands and Grassland Management District, where the Partners in Wildlife program restores old fields to grassland habitat, which are then maintained in an early successional stage by private landowners.

Embrace What Feels Right to You

Upon purchasing our initial acreage (7+ acres) the land was 65% scrubby, early successional growth with the remaining 35% being fragmented, forested, what I would call “islands”. The southern border to our property (55+ acres) is 75% rolling, hay pasture with the remaining 25% being fragmented, forested islands. To the south of that is 50+ acres of 100% forested habitat. This collective 112+ acres and then some, was initially one parcel that operated as a pastured cattle operation dating back to the 1800’s.

In July 2020, we were able to acquire 11+ acres of the rolling pasture which adjoins to the south end of our property. When considering a long term, management plan, weighing out the recent data trends, we embraced a grassland habitat restoration. In doing so, we are certain to displace some of the resident, early successional species but these same birds have more of that habitat nearby within agricultural and residential land. The smaller islands of forested habitat will require selective cuts to open up the tree canopy to create a non-interrupted plot to make it more appealing for grassland birds. In doing this, we will also displace some resident forest dwelling birds but these birds have larger spans of forest to choose from within the bordering acreage.

In conclusion, I am of the firm belief that doing something is better than doing nothing. I also believe that over analysis often leads to paralysis which leads to nothing getting done. Pick a plan, conduct your research, implement said plan and carry out the work that achieves the ideal habitat that YOU desire, and brings the most value to YOUR life.