Returns of the Winter Geese

My sons and I have been monitoring birds at Chicago’s Westside parks for almost a decade. Now that Ethan and Aaron are off at college, I still visit Columbus, Douglas, and Riis Parks at least three or four times each month. In each park I walk a route that takes me to most of the places where birds hang out and count every bird I see. I carefully count even the most common species, like American Robin, European Starling, and Canada Goose. We’ve gathered a lot of data over the years, and we’ve learned a lot about the seasonal changes in bird populations in this part of town. (Much of this data is summarized elsewhere on this blog: Columbus Park, Douglas Park, Riis Park.)

One thing that we quickly learned is that Canada Goose populations in the parks fluctuate quite a bit each year, as shown in the following graph of goose count data from Columbus Park, where we have been monitoring since 2007. (Click on the graph to make it larger.)

Seasonal changes in the Canada Goose population at Columbus Park on Chicago’s Westside, April 2007 through October 2015.

During the summer months there are often a few geese at Columbus Park, and some years a pair or two raise a brood of goslings. Other years the resident coyotes and goose-managing humans eliminate all geese from the park, at least during mid summer. Starting in September the park’s goose population begins to increase, and by Christmas Bird Count in mid December we often count 500 or more geese on the lagoon, lawns, and golf course at Columbus Park. During cold and snowy winters the geese may head elsewhere for a month or more, but goose populations usually increase again once the snow and ice melt. Sometime in March northward migration begins, and by April Canada Goose populations have fallen back to their late spring through summer levels. Although it’s not shown on the graph, goose populations in the park also fluctuate during the day, as many geese fly elsewhere at night.

Our monitoring data from Douglas Park is much less complete, since we only started going there regularly in 2012. However, the available data indicate that the yearly cycle at Douglas is similar to Columbus: Lower counts during the spring and summer, sharp increase in fall, drop off mid winter if there are deep snows, and at least a partial recovery before spring migration begins in March.

Seasonal changes in the Canada Goose population at Douglas Park on Chicago’s Westside. Although we visited Douglas several times a year starting in 2007, we only started monitoring there regularly in March, 2012.

We’ve always assumed that the winter Canada Geese in our parks come from somewhere to the north; however, I’ve wondered where, exactly, they spent their summers. Did they nest a hundred miles to the north, in Wisconsin? Or a thousand miles or more from Chicago, in arctic Canada? I’ve also wondered if the winter geese are loyal to one park, returning day after day, month after month, or if they wander from park to park, county to county, state to state, always looking for greener grass? And finally, I’ve wondered if the same Canada Geese return to Chicago, and maybe even to the same park, year after year?

I stumbled on some answers to my questions last December (2014) at Douglas Park. I was following my usual route around the north lagoon when my path was blocked by a small flock of geese. I slowly walked to and through the flock, and as they parted to let me through, I happened to look down. Here’s what I saw:

Canada Geese with leg markers C120 and C105, seen on December 3, 2014, at Douglas Park.

In all my years of monitoring birds, I had never seen markers like these. Of course, I rarely got this close to geese, and when I did I rarely looked at their legs. Looking around online I found a United States Geological Survey (USGS) website where I could submit my marker observations. I completed online forms for these two geese, and a few weeks later I received an email with a certificate of appreciation that looked like this. (I removed the bander’s address to respect his privacy.) :

Certificate of Appreciation for submitting data on the goose with leg marker C120.

Now I had at least a partial answer to one of my questions about Chicago’s winter geese. Both C120 and C105 had been banded the previous summer in Thunder Bay, Ontario, Canada, when they were too young to fly. Intrigued, I started paying much more attention to goose legs as I monitored birds. By slowly walking through goose flocks on the lawns and ball fields, I was able to address another question when I relocated both C105 and C120 at Douglas Park later that month. It seemed that at least some geese were returning to the same park more than once.

By staring at lots of goose legs through the winter and early spring of 2014-2015, I eventually found eight different leg-marked geese at Douglas Park, two at Columbus Park, and six at Steelworkers’ Park on Chicago’s far southeast lakeshore (where my younger son, Aaron, monitors birds). Once the winter’s snows melted, I also started seeing a different sort of marker, a white neck collar with black letter and numbers:

Canada Geese with neck collars 66C and 78A, seen at Columbus Park on Chicago’s Westside, on April 8, 2015.

Following up on information in the Certificates of Appreciation I received for the collared geese, I learned they had been marked the previous summer by a local research project, the Ecology of Wintering Canada Geese in the Greater Chicago Metropolitan Area (more information here and here). Through the spring I found eleven different neck-collared geese: Two at Douglas Park, six at Columbus Park, one at Riis Park, and two at Steelworker’s Park.

Even after local goose populations had decreased in the spring I kept looking for marked geese, but I did not see any after late May. However, in early August I received an email from the Canadian goose bander informing me that C165 had returned to Thunder Bay, Ontario.

As usual, local goose populations started increasing in September, and on September 30, 2015, I found two marked geese at Douglas Park, C120 and C151. I now had a partial answer to another of my questions, since I had seen C120 at Douglas twice before during December, 2014. Additional visits to Douglas Park through mid October located four more geese that I recorded the previous winter. In other words, by October 18, five of the eight leg-marked geese seen at Douglas during the winter of 2014-2015 had returned to the park.

Although I continue to stare at goose legs and necks in Chicago Parks (and plan to do so for years to come), this seems like a good time to tabulate my findings to date. The table for Douglas Park pretty much summarizes what I’ve learned so far:

Table summarizing data on marked Canada Geese at Douglas Park, Chicago, from December, 2014, through October 18, 2015.

Looking back at the questions I asked earlier in this blog post, here are some partial answers. (I call the answers partial because I saw markers on about one-in-a-hundred winter geese.):

• Where did the winter (and spring) geese spend their summers?  My sample includes both geese banded during summers in Canada and geese banded during summer of 2014 in the Chicago area.
• Are the winter geese loyal to one park, returning day after day?  My sample includes five geese that were present at Douglas twice in a month.
• …month after month? Two of the seven geese that were seen at Douglas during December, 2014, returned to Douglas after the winter snows melted, during March, 2015. (Apparently they sought greener pastures when the snow got too deep at Douglas Park.)
• Do the same Canada Geese return to Chicago, and maybe even to the same park, year after year?  Five of the eight leg-banded geese seen at Douglas Park last winter have been seen in the park so far this fall.

One more interesting finding from the age column of the Douglas Park table. The oldest goose in that sample, A657, was at least one year old when it was banded during July, 2008. That means it could have spent seven or more winters in Chicago before I finally saw it. I really wish I knew back then that goose legs could be so interesting!

My Douglas Park sample has more leg-marked geese than collared geese, but that pattern is reversed in my Columbus Park sample, as shown in the following table:

Table summarizing data on marked Canada Geese at Columbus Park, Chicago, from December, 2014, through mid October, 2015.

Of the two leg-marked geese seen at Columbus Park, one returned multiple times, both before and after the winter snows. Also, with a larger sample of neck-collared geese at this park, maybe it’s time to ask, why did I only see collared geese after the winter snows? Hundreds of geese received neck collars in the Chicago area during summer 2014, and even if they migrated south at some point, they could have been in the area for a couple months after banding. Neck collars, unlike leg markers, are pretty obvious when you are counting geese, even if they are too far away to read the numbers. I can make excuses for not seeing leg markers: They can’t be seen when the geese are on water or in the air, and they can’t be seen when the geese are far away or when the grass is too tall. Therefore, absences for leg markers probably don’t mean very much. However, I can’t make excuses for missing neck collars, especially when I was already looking for the much less conspicuous leg markers. There’s got to be an interesting story about the travels of neck-collared geese, but my Douglas and Columbus data are too sketchy to tell it. However, data from two other parks provide a bit more information about the collared geese.

Riis Park, on Chicago’s northwest side, attracts fewer geese than Douglas or Columbus Parks. Perhaps that’s why I only found one marked goose there, neck collar C111:

Table summarizing data on marked Canada Geese at Riis Park, Chicago, from December, 2014, through mid October, 2015.

Like the other collared geese this one did not appear in the park until spring. Unlike the collared geese from Douglas and Columbus, this one stuck around for awhile: I saw it on both April 1 and May 27 at Riis, and I also saw it during the May 9th Illinois Spring Bird Count, at Garfield Park a few miles southeast of Riis. Like the other collared geese, it has not been seen since May, 2014 — at least so far.

Finally, here’s some data about marked geese seen at Steelworkers Park on the far southeast side of Chicago. My son, Aaron, and I visited this area once or twice a week until Aaron left for college.  Aaron monitors birds in and around the entire South Works steel mill property, but all our marker sightings were on the lawn Steelworkers Park, on Lake Michigan just north of the mouth of the Calumet River:

Table summarizing data on marked Canada Geese at Steelworks Park, Chicago, from December, 2014, through mid October, 2015.

There was one day in March when we saw a lot of marked geese at Steelworks Park: Six with leg markers and one with a neck collar. Those geese then disappeared, perhaps flying north or maybe just deciding that the grass at nearby Rainbow Beach and Calumet Park was more tasty. A second collared goose (24C, a male) was seen at least four times during April and May (April 2 and 16, May 2 and 21). Sometimes 24C was seen with other geese, and sometimes he was all alone. By May there were many goose nests on the old ore retaining walls near Steelworkers, so it’s possible 24C was the male in a mated pair. However, we never saw him with goslings, so we will never know for sure.

That’s where things stand as the end of October approaches. I’ve begun to answer some of my long-standing questions about wintering Canada Geese by piggy-backing on other people’s efforts. (Banding Canada Geese in July must be hot and dirty work!). I find the results amazing, but not surprising. Amazing things happen in goose brains to make them return time and again to the Westside parks. But they’re birds, after all, and birds do even more amazing things every migration season.

My findings are at most a few pixels in a much larger picture of Canada Goose yearly cycles, but they are a start, and they are the pixels I’m going to value most. Of course the two-year Ecology of Wintering Canada Geese in the Greater Chicago Metropolitan Area is going to fill in a lot more pixels in the Chicago area, and I look forward to reading their reports.

Until then, I’ll keep looking at goose legs and goose necks everywhere I go. If you do the same, and you find any of “my” geese, please report them on the USGS website. I’d also appreciate it if you send me a message about your sighting.