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Current Research Focus

Where we are, where we have been, and how our focus has evolved.


Radar Location Map

Radar Unit Location MapTwo avian radar units have been located around all of the Great Lakes since 2011. Some seasons had the radar units (named Batman and Robin) at one location each for the entire season. Once the general migration pattern was better understood, we were able to move the radar units to a second location each and split the season in two. This way we were able to expand the shoreline coverage to a much greater area. Additionally, in the spring of 2013, a long range horizontal radar was installed on the Batman radar unit which extended its range out to about 6 miles. The long range radar lets us see what is happening at a greater distance from the radar, including the potential for looking out farther over the water into the lake.


Current Season

Spring 2018

Our project shifts gears to look at comparing between sites and how data we gather on migration relates to work on the ground to improve habitat for migrants. We are examining how migrants interact with Lake Superior, either crossing it or going around it and we have placed our radar units near Ashland, WI and Duluth/Grand Marais, MN to examine this area. We are proud of our partnership with the Bad River Band of Lake Superior Chippewa Tribe this seeason and are working with their wildlife department on sharing our data to work collaboratively during this season.





Previous Seasons

Fall 2017

Continuing with our investigations of urban landscapes and migrants, our radar units made the trip to Cleveland, Ohio and Erie, Pennsylvania for the fall migration season. We are also starting out a project working with the Motus tower network to track migrants with radar as well as individual tags! We hope to learn a great deal about migration from these sites, including how, when, and under what conditions migrants are crossing over the lakes when they head south.

Spring 2017

How do birds and bats interact with a different environment such as dense urban landscapes while they are migrating? That is one of the questions we are asking this season as we venture to Chicago and Northern Indiana along Lake Michigan.

Fall 2016

With many of the gaps filled in on the map of the Great Lakes, we are heading back to New York for the fall of 2016. While we may have covered the map to a decent degree, there are many differences between spring and fall and we are aiming to return to many of these sites to examine these differences. We hope to gain insight into how migrants cross and circumnavigate an east-west lake during the fall.

Spring 2016

In a first for the radar team, we returned directly to the sites we surveyed the previous season to observe the changes in activity between the seasons. Returning to Lake Huron will give us more detail on these sites and how migrants use them. We have multiple fall seasons along Lake Huron but this will be our first spring. Exciting things are coming soon from looking at the same site across a much longer period than we normally survey for!

Fall 2015

The radar team continues to fill in gaps in our knowledge of the Great Lakes by placing the radar units along the shoreline of Lake Huron in the northern part of Michigan for this season. By continuing to fill in areas of the shoreline that we have not surveyed, we can gain a better understanding of migration as a whole, as well as how locations differ in terms of the migration of birds and bats.

Spring 2015

Radar Unit at Brower

Photo by Nate Rathbun/USFWS

During this season, the radar units were deployed to both the north and south shores of Michigan's Upper Peninsula. This placement allowed us to compare patterns of migration where targets were approaching the peninsula from the south with patterns of targets observed leaving the peninsula to the north. This season also provided opportunities to work with local biologists at Pictured Rocks National Lakeshore and Seney National Wildlife Refuge.


Fall 2014

For the first time, the radar units will be located on Lake Superior, completing their full circuit of the Great Lakes and surveying area the furthest north they have been. In addition to covering new areas, we will be looking for examples of the heavy daytime raptor migration that the north shore of Lake Superior is famous for and may use some of this data to identify patterns that may also have been seen at other sites along the Great Lakes.

The many unique features of Lake Superior may lead to some

interesting and unanticipated radar observations along its shoreline!


Radar Unit at Brower

Photo by Nate Rathbun/USFWS




Spring 2014


In their most ambitious season to date, the radar team moved the units between 9 different sites in order to compare activity between the shoreline and approximately 15 miles inland. The east shore of Lake Michigan is now the first shoreline where we have data from both a spring and a fall season with our radar units, as Spring 2011 in Wisconsin was conducted with different radars than our survey in Fall 2013. The Spring 2014 project was an extension of the gradient analysis conducted in Fall 2013 but had a larger distance between shoreline and inland sites, covered more locations, and was stretched out along 130 miles of the eastern shore of Lake Michigan. The field season was also extended through late June to examine activity that occurs after the main part of migration has ended.






Radar Unit at AlpacaPhoto by Nate Rathbun/USFWS

Fall 2013

The radar units were located in Sheboygan and Manitowoc Counties, Wisconsin. This season was aimed at evaluating the width of the corridor of migrants. After calibration on the shoreline, one radar unit was moved inland 6 miles to compare numbers between there and the radar unit on the shoreline. The data from this season will help to evaluate how wide an area is used by migrants and if they are concentrating along the lakeshore. The data may also help determine where to focus on conserving stopover habitat. Comparing the behavior of migrants inland with those on the lakeshore may also shed some light on times of the day that they may most be at risk from collisions.



Spring 2013

Radar Unit at Russell FarmPhoto by Nate Rathbun/USFWS

This season the radar units made the long trip to New York and spent some time on Lake Ontario and also inland of the lake near the Iroquois National Wildlife Refuge. The Robin unit was located in western New York in Orleans and Genesee Counties and the Batman unit was located in Wayne and Jefferson Counties. The behavior of migrants differs greatly between spring and fall on east/west lakeshores such as Lake Ontario and Lake Erie. In the spring many migrants concentrate along the lakeshore before crossing over the lake moving north. Other migrants follow the lakeshore to take the longer, but possibly less risky, trip around either end of the lake. These differences may complicate efforts to understand how, when, and where the migrants are moving as some individuals of the same species may choose different strategies. This area was also one of the hardest hit by White Nose Syndrome in bats and understanding bat migration in the area may be critical to saving those species. Check out our seasonal report for this season!



Radar Unit at SunsetPhoto by Dan Nolfi/USFWS

Fall 2012

Our crew took on the ambitious task of moving the radar units mid-season for the first time. The season started out on the Upper Peninsula of Michigan with two locations in Delta County, Michigan, one on the western edge of Green Bay and one on the Garden Peninsula. These locations were chosen to evaluate how migrants used peninsulas and the mainland when migrating. Would the migrants be concentrated on the peninsulas like a funnel and then cross over the water to the other side or would they travel on the mainland where they would not have to cross small stretches of water?

Radar Unit at MNVNWRPhoto by USFWS






In the middle of the migration season, we moved the radar units around 300 miles southeast to either side of Saginaw Bay in Iosco and Huron Counties. In these locations we could see a picture of how migrants reacted to Saginaw Bay during their migration south in the fall. Did they cross the approximately 20 mile wide bay and travel down through the thumb of Michigan or did they follow the coastline around to Bay City and travel south through the Shiawassee National Wildlife Refuge?



Two Radar Units at MNVNWRPhoto by USFWS

Summer 2012

The radar units spent the summer in Minnesota near the Twin Cities at the Minnesota Valley National Wildlife Refuge near where the radar crew is based at the Region 3 Regional Office in Bloomington. While we were not examining migration during the summer, the radar units were undergoing many tests for calibrating them to ensure that we were collecting our data as effectively as possible. The radar units were also compared to see if the units counted the same number of targets in an area in preparation for conducting gradient studies along the lakeshore in future seasons. By conducting these calibration studies during the summer we did not have to sacrifice data collection during the migration season. We would like to thank the refuge staff for their cooperation and assistance in using the Rapids Lake Unit for our project.




Radar Unit at Penn ShorePhoto by Nate Rathbun/USFWS

Spring 2012

Migration on an east/west lakeshore was examined for the first time this season with the radar units stationed in Erie County, Ohio and Erie County, Pennsylvania. On the west side of the lake in Ohio, the radar site could evaluate the movement of migrants in an area with many bird migration hotspots such as Ottawa National Wildlife Refuge, Black Swamp Bird Observatory, and Magee Marsh. This radar unit could also see if migrants were heading to the islands to cross over Lake Erie or if they were heading around the lake to either end. The radar unit in Pennsylvania was located near Presque Isle State Park and examined how migrants were moving around the eastern end of the lake and also had a birding hotspot nearby. By stationing the radar units towards either end of the lake, we could get an idea of how the migrants were using each side differently.



Inspecting the Radar UnitPhoto by Nate Rathbun/USFWS

Fall 2011

This migration season was the first for much of the radar team and the radar units were located on either side of Michigan in Oceana and Huron Counties. Learning how to use these complex pieces of equipment while collecting data is a difficult task but our team was up to the challenge. This season focused on determining how migrants were using the north/south shorelines on either side of Michigan. Development of wind resources in Michigan is occurring quickly as the state has many areas with high wind speeds. The state also has the most shoreline of any on the Great Lakes. By starting our project in this location, we began addressing one of the areas that may have the most impact on birds and bats from the development of wind power. Check out our technical report for this season!


Spring 2011

Loaner Radar UnitPhoto by USFWS


Every project has to begin somewhere! The two radar units were stationed in Manitowoc County, Wisconsin with the goal of comparing inland migrant activity with shoreline activity. Due to a delay in delivery of the Batman and Robin radar units from the manufacturer, the season was mostly conducted with loaner radar units that were drastically different than the radars used in the seasons since then. While unfortunate for the radar comparison, this season allowed the radar team to evaluate the pros and cons of another type of radar (X-band) that is used by many other studies. When the Batman and Robin units did arrive, their time in the field allowed for familiarization with them in a field setting before deployment in the fall.







We would like to thank all of the landowners that allowed us to operate the radar units on their land and also for the variety of assistance they provided while we were there.

Last updated: May 3, 2018