It’s 5 a.m. on a cool morning in mid-June and my friend, Ann Russ, has joined me for a day of “atlasing” in Cook County. We are spending the morning documenting the breeding birds present in a 9-square-mile block in the northeast corner of Township 62X1a, about 7 miles northeast of Grand Marais (Figure 1), one of 20 atlas blocks I was assigned to survey in the month of June. One major road, the Gunflint Trail, cuts across the eastern edge of the block. Otherwise, its extensively forested landscape is only dissected by a few unpaved roads and several old logging trails that are largely inaccessible to my small, low-lying Prius. After making a few quick stops along the narrow and winding Gunflint Trail to record which birds are singing, a somewhat perilous endeavor in the morning’s dim light, we pull onto the public access at Elbow Lake and make several stops before walking down to the water’s edge.
The morning chorus of bird songs is already in full swing. Black-and-white Warblers, Rose-breasted Grosbeaks, Red-breasted Nuthatches, and Winter Wrens are just a few of the species heralding the sunrise. No ducks are visible on the lake but a Northern Waterthrush is singing along the shoreline. The sheer abundance of birds and their remarkable diversity in this region is extraordinary. Indeed, a narrow forest belt that stretches from northeastern Minnesota east across northern Wisconsin, northern Michigan, and New England supports a higher diversity of breeding birds than anywhere else in North America. Ann and I have our work cut out for us this morning as we attempt to document the breeding status of as many birds as possible in this one densely forested block.
For five summers, beginning in 2009, hundreds of bird enthusiasts like Ann and me contributed their time to document the breeding status of birds in thousands of 9-square-mile blocks across the state. They were participating in Minnesota’s first breeding bird atlas, an important conservation initiative designed to document and map the distribution of every species that bred in the state during the five-year window from 2009 to 2013.
What is Atlasing?
The word “atlas” typically refers to a collection of maps, one often depicting roads, cities, and land ownership, to help guide our travels. More recently, the verb “atlasing” has come to embrace the effort to geographically catalog the distribution and abundance of elements of biodiversity during an established time period. Made possible by engaging hundreds of knowledgeable volunteers, “atlasing” had its origins in Great Britain in the 1950s when volunteers helped botanists document and map the diversity and distribution of the country’s flora using a 10 km x 10 km grid. Prior to this effort, the presence or absence of species was recorded at the scale of vice-counties, a subdivision of the country’s 86 counties. Mapping at the much finer scale of 10-square-km blocks not only provided considerably more detail but also established a meticulous baseline for monitoring future changes. It also provided comprehensive data to better inform local conservation and land-use planning efforts. Published in 1962, the Atlas of the British Flora became a sentinel publication that prompted others to initiate similar efforts.
Given the popularity of bird watching, it was only natural that an atlas of birds soon followed with the publication of the Atlas of Breeding Birds of the West Midlands in 1970, an area encompassing three counties in Great Britain. This was soon followed by the 1976 publication, Atlas of Breeding Birds in Britain and Ireland. The movement quickly travelled overseas and by 1974 Massachusetts was the first state to launch a breeding bird atlas followed by Vermont in 1976, Maine in 1978, and New York in 1980. In the ensuing years breeding bird atlas efforts continued to sprout up across the United States and Canada. Indeed, by the year 2000 Minnesota was the only state in the Mississippi River Valley that had not launched a similar initiative. In a state as large as Minnesota, with thousands of acres of inaccessible lands, there was concern that soliciting enough volunteers to successfully complete an atlas would be too difficult and would compromise the ability to achieve statewide coverage, a basic premise for successfully conducting an atlas effort.
Enter Bird Conservation Minnesota (BCM), a collaborative of individuals, organizations, and institutions organized in 2003 to improve the scope of bird conservation efforts in the state. Undeterred by the numerous challenges, one of the primary goals of BCM was to seek funding to conduct a statewide breeding bird atlas. After numerous meetings and workshops, Audubon Minnesota, working with other BCM partner organizations, successfully secured a major state appropriation from the Minnesota Environment and Natural Resources Trust Fund, as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR), to launch Minnesota’s first statewide atlas.
With additional support provided by Audubon Minnesota, the Minnesota Department of Natural Resources, the Minnesota Ornithologists’ Union, the Natural Resources Research Institute of the University of Minnesota Duluth, and the U.S. Fish and Wildlife Service, preparatory work began in 2008 and the atlas was officially launched during the 2009 breeding season under the direction of Audubon’s newly hired atlas coordinator, Bonnie Sample (Figure 2).
Organizing the Atlas and Addressing the Challenges
The key to any successful atlas effort is a strong organization focused on ensuring systematic statewide coverage. Minnesota’s Breeding Bird Atlas (MNBBA) used the state’s grid of townships, each 36 square miles in size, as a basis for organizing its sampling efforts. Each township was divided into four 9-square-mile blocks; the block in the NE quadrant of the township was randomly selected as the priority block for sampling breeding birds (Figure 3). The goal was to thoroughly sample all the breeding birds in each of the 2,352 priority blocks. Data could also be collected from the remaining 7,422 blocks as time and interest allowed.
The next challenge was to ensure that breeding birds were adequately sampled in each priority block. The atlas relied on four primary sampling techniques.
First, project coordinator Bonnie Sample recruited hundreds of volunteers from across the state, as well as several regional coordinators to further assist with recruitment. Volunteers are critical to the success of atlas efforts worldwide as they contribute thousands of hours collecting valuable field data that would otherwise be cost-prohibitive. Birding enthusiasts are drawn to contribute their time for many reasons but perhaps chief among them is the knowledge that they are “birding with a purpose”. Many birders enjoy going beyond just observing a species to using their patience, knowledge, and keen observation skills to decipher a species’ breeding status, knowing that their contributions will be well-documented and will be a valuable contribution to conservation.
Second, because it was inevitable that most volunteers would be concentrated in the Twin Cities and in larger outstate communities such as Duluth, Brainerd, and Rochester, another critical decision was to hire skilled field staff to survey blocks in many of the more remote localities, including far northwestern, southwest, and northern Minnesota.
Atlasers were provided with lists of all the species expected in each region of the state, along with detailed survey guidelines outlining expectations. It was recommended that they spend approximately 20-25 hours per block in an effort to document at least 75% of the expected species. Surveys were to be done between March and August. Although most species breed during the summer months, atlasers were encouraged to make at least one visit to the block in March or April. Some species, such as Great Horned Owls, Barred Owls, and Gray Jays, may actually begin nesting in late winter or early spring.
Independent of these surveys, a third sampling technique was employed to gather data in the priority blocks: systematic point counts. These point counts were designed to provide a standardized baseline for assessing habitat relationships, species relative abundance, and population size, and to enable the detection of statistically accurate population changes over time when the atlas is repeated. Standard atlas work is only focused on determining the presence of a species and its breeding status. Data on abundance and habitat are not collected. Point counts, on the other hand, map the presence and location of every bird heard and observed during a 10-minute sampling period at a precise point on the landscape. This allows biologists to assess species abundance and to correlate each species detection to specific habitats when the data is overlain with satellite imagery.
Led by Dr. Gerald Niemi at the University of Minnesota Duluth’s Natural Resources Research Institute (NRRI), Minnesota was one of the first states to complement the general atlasing effort with point counts. Skilled field observers, hired for their expertise in identifying bird songs, conducted three ten-minute point counts in each priority block. The first point was the closest access point (e.g. a suitable road or trail) to a randomly selected point in the block; the second and third points were placed in the closest access point to the most abundant and second most abundant habitat in the block (Figure 4).
At each point the observer recorded every bird heard or seen within the ten-minute period. Although the amount of time spent in each block was limited, the point counts ensured a statistical assessment of the population in each block and helped address the uneven geographical effort of volunteers. Areas surrounding major urban centers or those in some of the “best” birding places often have more bird detections and, as a result, more detections of rarer species by volunteers. The systematic approach helps to determine whether or not these distributions reflect effort versus true variation in the distribution of breeding birds. Depending on the habitat diversity within the block, the three point counts typically provided data for 20 to 30 species.
Finally, a fourth method of data collection was employed. The atlas actively solicited survey data collected by other organizations during the five-year sampling period that provided data on less common species, species difficult to survey, or on species that occur in areas difficult to access. Examples included data collected by the Hawk Ridge Bird Observatory on owls (Figure 5), data collected by the Minnesota Biological Survey on rare species, and data collected on nesting rookeries of American White Pelicans and Double-crested Cormorants by the University of Minnesota.
In the Field
At the Elbow Lake access, Ann and I call out every bird we hear and observe, recording and classifying each detection using a standard set of codes used by similar atlases conducted across the country. We classify each species in the block as an observed species, a possible breeder, a probable breeder, or a confirmed breeder, based on the type of information we collect. When Ann catches a quick glimpse of a Turkey Vulture flying overhead we classify it as an observed species but when we spot a Broad-winged Hawk perched in a tree within the forest, we classify it as a possible breeder as it was seen in suitable breeding habitat. Other types of evidence allow us to determine if a species is a probable breeder (e.g. observing a pair in suitable nesting habitat) or a confirmed breeder (e.g. finding a nest with eggs or young, or observing nest-building activities).
Our goal is to gather enough evidence to classify the majority of species as probable or confirmed breeders. In Minnesota’s northwoods, where the bird community is dominated by wood warblers, vireos, thrushes, and wrens that often sing from the pinnacles of tall aspen, spruce, and pine trees, confirming nesting can be quite a challenge. This is especially true in the dim light when Ann and I depend entirely on our listening skills to identify all the members of this early morning’s chorus. But, if we hear five or more males of a given species singing, our codes allow us to designate the species as a probable breeder in the block. Between us, it takes very little time to identify some of the block’s most common species as probable breeders using this criterion, including the ubiquitous Ovenbird loudly proclaiming “Teacher, Teacher, Teacher”, followed by White-throated Sparrows, Red-eyed Vireos, Nashville Warblers, American Robins, and Chestnut-sided Warblers.
Back in the car we drive further north along the Gunflint Trail to a spot where we can leave our vehicle and hike along an old trail that eventually takes us to Pickerel Lake. Time and limited access will make it difficult to cover the entire block so our strategy is to examine an aerial image of the block and attempt to visit all the primary habitats discernible in the photo. Most notably, we want to survey a small area lacking forest cover that appears just beyond the turn-off. The site turns out to be an abandoned gravel pit where we hear the distinctive “Dee-ee, Dee-ee” alarm call of a Killdeer. Try as we might, we can’t locate a pair or nest so the species is simply recorded as a possible breeder. An Eastern Phoebe also is singing in a lone tree along the edge of the pit (Figure 6).
This morning we never reach Pickerel Lake, turning back to retrace our steps knowing how much more territory we have yet to cover that day, including at least one other nearby atlas block. After spending five hours in T62X1a we compiled a list of 38 species, including 19 probable breeders, 18 possible breeders and one observed species. We have added 21 species to the list of 22 compiled by the individual who conducted the three 10-minute point counts during an earlier field season. Over the course of the entire five-year atlas sampling period additional visits by myself and other volunteers working in the region will add more species to our growing list. In the end, a total of 69 species will be recorded, including 15 confirmed species. It can take a village to thoroughly survey an atlas block let alone thousands of atlas blocks! Indeed, after five field seasons, more than 700 volunteers collected data in 2,339 of the 2,352 priority atlas blocks (13 priority blocks were inaccessible) and in a total of 6,622 atlas blocks throughout the state! Statewide, 249 species were identified. Field observers in the Brainerd Lakes Area, led by regional coordinators Ken and Pam Perry, did an amazing job leading the state with the highest number of blocks with more than 75 species each (Figure 7). There were at least two blocks in the state where 101 species were reported: one in central Aitkin County and one along the Minnesota River bordering both Lac qui Parle and Big Stone counties.
Compiling and Analyzing the Results
Although the 2013 field season was the official end of the Minnesota Breeding Bird Atlas, much work remained to be done. Bonnie Sample retired after leading the successful field effort. I was hired in the fall of 2014 to bring the atlas to completion, working closely with Dr. Niemi and his staff at NRRI and volunteer Jan Green. The first important task was to review all 380,000 individual records that were compiled. A technical team of knowledgeable field ornithologists reviewed many of the records collected by the atlas from 2009 to 2014. Now, each record would be reviewed one more time to ensure the data were as accurate as possible. Dr. Niemi and Jan assisted me in this arduous task which took nearly six months.
Identifying many of Minnesota’s common species in the field is usually not a problem but some species can create vexing identification challenges. Even experienced birders, for example, can confuse the rapid, high-pitched trill of a Dark-eyed Junco with that of the common Chipping Sparrow. As a result, we decided to accept Dark-eyed Junco records only if the birds were actually observed (there is no confusing the two species when seen!) or if the song was identified by a very skilled field observer. Distinguishing the song of a Philadelphia Vireo from that of a Red-eyed Vireo presents similar challenges. What about a Black-and-white Warbler that was seen and heard in Fillmore County, along the Iowa border, during the first week of June? Was it a late migrant or a possible breeder? Or a Sharp-shinned Hawk observed in central Minnesota in June? Was it really a rare Sharp-shinned Hawk or the near look-alike, but larger and more common bird, the Cooper’s Hawk? Were there notes accompanying the observation? Does the observer remember more details? These are examples of the issues that needed to be addressed before any of the data could be summarized and analyzed in more detail.
Once we were satisfied with the quality of the data, work began in earnest during the fall of 2015 to conduct further analyses. Dr. Niemi and his staff at NRRI took the lead in several areas including producing the final maps for each of the 249 species that were documented breeding in the state. Using the data gathered from point counts, they also assessed the habitat relationships for many species and prepared sophisticated models incorporating additional data on habitat, landscape context, and climate to predict the breeding distribution of 115 of the more common species across Minnesota.
While these analyses were underway, work also began in late 2015 to prepare written accounts of each species. Before we launched this task, however, we made an important decision. We would not simply summarize the outcomes of the atlas for each species but would place them in historical context, beginning with what was known about the species in the mid-to late 1800s.
In this regard, Minnesota is blessed to have several written comprehensive accounts of Minnesota birds dating back to Dr. Philo Hatch’s first report on the birds of Minnesota in 1874. He would follow with two more publications in 1881 and 1892. Unfortunately, the credibility of many of his observations and those he compiled from others were often questioned by later ornithologists but they do provide interesting insights on many common species. Dr. Hatch’s works would be followed with a far more credible and impressive two volume book, The Birds of Minnesota by T.S. Roberts in 1932 (Figure 8). To date, this is considered the ultimate authority on the distribution and status of the state’s avifauna from the late 1800s through the early 1900s. Books by Jan Green and Robert Janssen in 1975 and by Robert Janssen in 1987 provided additional information and status updates on Minnesota birds. We were also able to draw from a plethora of field studies supported by the DNR’s Nongame Wildlife Program and data generated by the Minnesota Biological Survey, both of which began in the 1980s.
Using these references and studies to prepare a comprehensive overview of each species, it would take nearly two years to complete the writing task.
The Minnesota Breeding Bird Atlas Website
In the late summer of 2016, work began to design a new website (https://mnbirdatlas.org) to display all the results and the final species accounts. Staff at NRRI took a leading role including Dr. Niemi, Dr. George Host, Nick Walton, Ed Zlonis, Kim Rewinkel and Norm Will, all working closely with local web designer Jane Reed. The site was designed to highlight two primary features: the species accounts and an interactive map. The former not only provides information on the species’ history in the state but provides summaries of its breeding habitat, population abundance, and conservation status, accompanied by detailed lists of literature citations where readers can find additional information. Beautiful photographs of each bird accompany the accounts, including many from outstanding north shore photographers David Brislance, Karl Bardon, Michael Furtman, and Sparky Stensaas. An interactive map displaying the MNBBA results also accompanies each species account and allows the user to select numerous options for displaying the data and for selecting base maps that display roads, public lands and satellite images.
Finally, by September 2017, most of the work analyzing the data, writing the species accounts, and designing the website was completed. The last task was to conduct a test launch. Twenty-four individuals were asked to review and test the website, providing valuable feedback on elements that worked well and those that required some tweaking. After incorporating their recommendations, on November 6, eight years after the atlas was launched in 2009, the website was complete and the first Minnesota Breeding Bird Atlas was ready to share with the public.
A Glimpse of Some Atlas Results
Changes in habitat are invariably accompanied by changes in the landscape’s flora and fauna. The loss of at least 98% of Minnesota’s native prairies has had a devastating impact on many grassland birds including the Chestnut-collared Longspur, Baird’s Sparrow, and Sprague’s Pipit. Similar impacts to wetland species are also notable including Franklin’s Gull, Northern Pintails, and Black-crowned Night-Herons. Although the changes have been less dramatic in the northern forest, particularly the Arrowhead Region, increasing development has occurred in many areas and the northern mixed deciduous-coniferous forest is now more heavily dominated by deciduous cover. Perhaps the most obvious change observed by many northern residents is the number of bird species that are moving northward including the Red-bellied Woodpecker and Northern Cardinal. Both are species that have benefitted not only from habitat changes but also from the increasing interest in winter bird feeding. The atlas documented their continued northward expansion including several possible breeding records of Red-bellied Woodpeckers along the Canadian border while cardinals were found breeding as far northeast as Grand Marais. Wild Turkeys continue their expansion northward, the atlas documenting their presence throughout Aitkin and Carlton counties, southern St. Louis and northern Itasca counties and in far northwestern Kittson County. Sandhill Cranes also continue their resurgence and are now a regular but uncommon species even in the Arrowhead Region. A rare Hooded Warbler was even sighted at Hawk Ridge on two days in June of 2009!
In contrast, some northern species are slowly expanding their range to the south and west including the Merlin and Common Raven. But the Evening Grosbeak (Figure 9) now has a more restricted breeding range. Originally found in the evergreen forests of Itasca and Koochiching counties east throughout the Arrowhead region, the species is now almost entirely restricted to St. Louis, Lake, and Cook counties with only a handful of reports in north central Minnesota. Indeed, in the latter half of the 20th century, Evening Grosbeaks appeared to be expanding both to the west and south in Minnesota. What prompted their original expansion and subsequent decline? Check out the species account.
What Does the Future Hold?
Continuing change is inevitable. Towns grow, suburbs expand; some habitats are lost while others are restored. Periodic changes in farm policies will continue to impact the amount of grasslands retained in planted cover or the number of acres growing corn and soybeans to feed the world. In northern Minnesota demands for timber impact the rate of forest change. And rising temperatures will inevitably affect the composition of the region’s flora and fauna. In 20 to 50 years will Minnesota’s northern forests continue to be the cradle of bird diversity that they are today? Will species typically associated with mixed boreal forests, such as the Canada Warbler, Cape May Warbler, and Winter Wren disappear from the state?
Atlasing is one of the best tools to track future change and answer such questions. Most states attempt to repeat their breeding bird atlases every 20 years, a practice recommended by the North American Ornithological Atlas Committee. Indeed, many of Minnesota’s neighboring states and provinces have already completed two atlases including Michigan, Iowa, South Dakota, and Ontario. The 2018 breeding season will be the fourth of five seasons for Wisconsin’s second atlas. The original founders of Minnesota’s Breeding Bird Atlas launched it with the hope that Minnesota birders will rise to the occasion once again in 20 years to launch the state’s second Breeding Bird Atlas. It’s never too early to start planning. In the meantime, having caught the atlasing bug, I’m heading east to Wisconsin!
MORE: Agate Asks the Author
Agate: Any ideas for how the Minnesota Breeding Bird Atlas might be used by people who are interested in bird-watching but not especially skilled in field identification?
Lee: There are numerous ways that the website can be used by people with a general interest in bird-watching. For example, it is a great tool for learning about all of the common species that people encounter in their backyard including Black-capped Chickadees, American Goldfinches, and Downy Woodpeckers, species that are easy to identify and that are encountered statewide. Perhaps one of the handiest tools is the interactive map which allows the user to pinpoint where they live and then identify all the birds identified during the atlas within a circle that can range from 2 to 100 miles from their home. The Using the Interactive Map tab, under Using the Atlas, provides more explicit directions. Some of the most satisfying feedback we actually received is that the website is a wonderful tool for all skill levels, from trained ornithologists to natural resource managers to casual backyard bird-watchers.
Agate: Do you have a favorite bird?
Lee: Yes, it’s the Winter Wren, a tiny northern forest bird with just an incredibly long and beautiful song. I’m always amazed at how much song can come out of such a tiny bird!!
About the Author
Lee Pfannmuller’s involvement with the Minnesota Breeding Bird Atlas began in 2009 when she volunteered to help the Atlas Coordinator, Bonnie Sample, launch the project. She also served as a regional coordinator, a field volunteer, a paid surveyor, and finally as the project manager responsible for leading the analysis of results and the development of the final website. While working on the atlas, she also spent time as the Interim State Office Director for Audubon Minnesota and as the State Planning Coordinator. Prior to this she worked with the Minnesota Department of Natural Resources for 30 years where she was Director of the Division of Ecological Resources from 1992 to 2007. She was responsible for directing and supervising over 20 different resource programs designed to manage Minnesota’s rare resources, native plant communities, lakes and rivers, and invasive species. Prior to this she worked for the Nongame Wildlife Program, the Natural Heritage Program, the Scientific and Natural Areas Program, and the Division of Minerals.