Carlos Avery Story of the Day

posted Jun 29, 2020, 10:25 AM by Jonathan Poppele   [ updated Jun 29, 2020, 10:28 AM ]

With Cedar Creek Ecosystem Science Reserve still closed to all but essential research, members of the Minnesota Wildlife Tracking Project moved our Summer Survey to the nearby Carlos Avery Wildlife Management Area. Over the weekend of June 13 & 14, socially distanced trackers explored roads and trails in the WMA and brought back our stories to share. Here are a few highlights. You can see all of our observations from the weekend here on iNaturalist.

Perhaps the largest surprise of the weekend was the relative lack of mammal sign. In a typical survey at Cedar Creek, our teams often return with scores of observations of mammal tracks from more than a dozen different species. Over this weekend, we collectively identified the tracks of just 6 species of mammals, plus the sign of five more. For half of those species, we made only a single observation. Those observations included a single fox scat and single coyote scat, as well as these fresh weasel tracks that were disappearing quickly in the wind—suggesting that the weasel had come through only a few minutes before this observation was made.

As usual, our trackers located the digging signs of local fossorial mammals. We can identify pocket gopher activity like this to species, because the plains pocket gopher is the one member of the family in this part of the state. But it is not so easy to identify mole tunnels to species. We have both eastern moles and star-nosed moles around the metro area. We have similar challenges identifying other tiny mammals, such as voles and shrews, from their tracks and sign. For positive identification, we usually need a skull or a carcass. On this survey, we turned up this masked shrew corpse. Since shrews scurry about much like voles, but are apparently much less appetizing, it is not rare to find nearly intact bodies—perhaps discarded by a disappointed predator.

The one mammal that we did find abundant tracks for was the common raccoon. An in particular, we found several spots where raccoons were raiding what appear to be bullsnake nests. We had found a dug-out snake nest once before on a survey at Cedar Creek. This weekend, we located more than a half-dozen. Bullsnakes are common in this area, as evidenced by the bullsnake trails we found crisscrossing many of the roads we explored. According to Moriarty & Hall's “Amphibians and Reptiles in Minnesota,” June is nesting season for bullsnakes and it seems that the raccoons were making quick work of these newly laid eggs—although in one of the excavated nests, we found an egg that was still intact.

Our team also recorded the tracks and sign of quite a few birds. Our findings included common and familiar species such as sandhill crane and American crow, but also a bank swallow nesting colony. As their name suggests, bank swallows historically formed their nesting colonies where erosion sheer faces along the sandy banks of streams and rivers. The species common name, and Latin name Riparia riparia, recognize these riparian roots. Over the past century, the species has broadened its habitat to include vertical road cuts and the edges of gravel and sand mine pits, like this one. The nesting holes themselves are similar to those of kingfisher, but appear more oval. They are distinctly wider than they are tall and, like kingfisher burrows, have two "tracks" along the base where the birds feet appear to shuffle as the enter and exit.

Finally, our surveyors ran across a huge diversity of insects and insect sign. Most of us of course are not entomologists, or even bug collectors, so our ability to interpret what we are finding is modest. But one sighting that is worth sharing is our first confirmed sighting of antlion traps. Antlion larvae excavate conical traps in sandy soil where they capture unlucky ants and other hapless critters. They are common, wide spread, and a favorite question on CyberTracker evaluations. But they are something that our trackers rarely encounter here in Minnesota. On a couple of occasions, we have found conical depressions in the sand at Cedar Creek that looked like antlion traps, but we were unable to locate the larvae to confirm this. On this occasion, there was no doubt. We watched the larvae excavating traps and drag an ant down into the sand. We also dug one out to get a close look at this stuff of insect nightmares.

It has been a treat to explore Carlos Avery during these months when we are unable to track at Cedar Creek. But we are looking forward to returning to our usual routes before long. The University of Minnesota plans to resume in-person instruction in the fall, and we have confidence that we will be able to hold our Fall Survey at Cedar Creek – perhaps with some modifications.

Mark your calendars for the weekend of October 2-3 and stay tuned for updates as the start of the school year approaches.

Book Review: Tracking Mammals in the Northeast

posted Jun 10, 2020, 8:39 AM by Jonathan Poppele   [ updated Jun 10, 2020, 8:47 AM ]

In her book A Field Guide to Tracking Mammals in the Northeast, Linda J. Spielman tackles one of the persistent shortcomings of tracking guides. Animal tracks vary enormously in appearance. As she writes in the introduction, “real tracks frequently deviate from perfect tracks,” and “may appear like the tracks of a completely different animal.” No one illustration or photograph can possibly convey this variation. Most guidebooks include at most two or three images of the tracks for a given species. Spielman illustrates eight to ten examples for every species.

Spielman's high-quality illustrations capture the range and variety of track presentations in a way no other book does. Different drawings show different amounts of splay in the toes; tracks with and without claws, dewclaws or tarsal pads registering; and tracks that resemble those of other species. The illustrations don't show small details of track morphology as well as David Moskowitz (Wildlife of the Pacific Northwest), or Mark Elbroch (Mammal Tracks & Sign), but the range of presentations makes this book a valuable addition to the tracking literature.

Spielman's text is also first rate. Her descriptions of animal behavior are clear and accurate. Her commentary and interpretations show that she has a huge amount of "dirt time" under her belt. And despite her obvious expertise, she avoids the common pitfall of over-interpreting what she has seen and presenting conjecture as fact.

As with most regional guides, A Field Guide to Tracking Mammals in the Northeast is useful well beyond its geographic range. Most of the thirty-three mammals covered in this book are found across the continental United States.

Every book makes trade-offs, of course, and this book has its downsides. The paper is lightweight and porous. While the book is small and light enough to carry anywhere, it may not hold up well in the field. The book does not include images of the animals themselves. The track illustrations are not life sized with small tracks are shown larger than life and large tracks are reduced. There is little information about sign. And, of course, some people just find photographs of tracks easier to interpret than illustrations. With the exception of the books durability, these are minor issues. And even the durability shouldn't keep anyone from buying this excellent book.

For anyone who has puzzled over a track that just didn't look like any of the illustrations in the field guide, this guide may be what you are looking for. For the intermediate tracker, in particular, it can help avoid many common mistakes in identifying tracks in the field. And for anyone who already has a library of tracking books, I would consider this a worthwhile addition.

You can purchase A Field Guide to Tracking Mammals in the Northeast here on

Note: is an online bookstore with a mission to financially support local, independent bookstores. Founded as an alternative existing online book sellers, shares 75% of its profits with independent bookstores, affiliate publications and affiliate authors. By using the affiliate link above, a portion of your purchase go to both local bookstores and to help support the Minnesota Wildlife Tracking Project newsletter and website.

June 2020 Natural Mystery

posted Jun 9, 2020, 7:50 PM by Jonathan Poppele   [ updated Jun 10, 2020, 8:50 AM ]

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May 2020 Natural Mystery Answered

posted Jun 9, 2020, 7:46 PM by Jonathan Poppele   [ updated Jun 9, 2020, 7:48 PM ]

The all new Peterson Field Guide to North American Bird Nests by Casey McFarland, Matthew Monjello, and David Moskowitz is in press. But its release date is still nearly a year away. That didn't stop Cheri Stockinger, Kirsten Welge, Liz Jaeger, Matthew Johnson and Mike Holtz from correctly identifying the species that laid these eggs and sharing some insights into the color and why these particular eggs are so dark. An honorable mention also goes out to Maren Miller who made a compelling case for another species. Congratulations to all of you!

As Matthew Johnson notes for us, these are the “robin's egg blue” eggs of an American Robin, Turdus migratorius.

Liz Jaeger summarizes the features here that are characteristic of American Robin.

“The nest has some mud on the exterior and a light lining of grass on the interior. Eggs are smooth, glossy, and oval, and have a relatively consistent color (i.e. not mottled or speckled).”

American Robins are one of a handful of songbirds nesting in Minnesota that can lay smooth, glossy, unmarked, blue-green eggs. Others include the Eastern Bluebird, European Starling, Gray Catbird, and Blue Jay.

Mike Holtz notes that the “nest structure doesn't fit bluebirds or starlings.” As Matthew Johnson noted about Eastern Bluebirds, and Kirsten Welge pointed out about European Starlings, both are cavity nesters and neither use mud in nest construction. Neither do Blue Jays.

That eliminates all the candidates except for the Gray Catbird. And Maren Miller made a compelling case for this being a Catbird nest:

"Gray Catbirds are known to lay dark green-blue eggs, approximately 1-5ish per clutch, that measure approximately 1 inch in length. Obviously, these eggs are dark green-blue (not light blue, like a Bluebird's or an Egret's; and not overtly speckled, like a House Finch's); and the clutch size of 3 eggs is certainly reasonable. Although we don't know how long each egg is, we can consider them in relation to the height of the nest. Gray Catbird nests are generally about 2 inches tall, meaning that we could stack two 1 inch Grey Catbird eggs on top of one another lengthwise to hit the top of the nest. When I "eyeball" the eggs in relation to the nest, it looks as though two eggs stacked on top of one another lengthwise would approximately equal the height of the nest—not an exact science, but again, the Grey Catbird egg hypothesis seems feasible.

Nest: If this nest doesn't belong to a Gray Catbird, a Gray Catbird should probably consider moving in here, because it's just about ideal for this bird—from the materials used to build the nest, to the nest's structure, to its immediate location and surrounding habitat. Gray Catbirds build nests with an eclectic array of materials, including twigs, straw, mud, and reeds, and the interior of their nests are often tightly woven—all of which we see in this photo. Gray Catbirds also tend to build their nest in "shrubby" locations that are close to the ground (unlike Robins, who prefer leafy trees), and the photo seems to document a brush-y habitat. Finally, Gray Catbirds are a pretty common species of bird on/around Picnic Island, so it would certainly make sense to see a GC nest with eggs in this location."

Mike Holtz
says he thinks “catbird eggs would be even darker, but I'm not sure that's enough to discredit this analysis.

As it happens, this nest was not in dense shrub, but on the horizontal limb of maple with a large wild grape vine growing along side—though that is not evident from the photo. I have been researching the nests of these two species, and haven't found anything in my study to eliminate Gray Catbird as a candidate based only on this photo. I'd love to hear from you if you have insights on this.  What I can offer is verification that this is a robin's nest—as I watched the mother return shortly after I took the photo of the eggs.

Maren also had some good insights as for why these eggs are such a dark color, explaining:

"I once read that certain birds' eggs appear green-blue because of a green-blue bile substance called biliverdin that is present in the female. A darker green-blue eggshell suggests that there is more biliverdin in the female; and biliverdin is also an antioxidant, so darker green-blue eggs indicate that the female and her brood are healthy. Male Catbirds seem to know that darker eggs are healthier eggs, which works in the female's favor: males are more inclined to stick around and help the female raise their chicks if they sense those chicks and the female bird are healthy."

Mike Holtz added to this “The eggs could be a darker blue in a first brood, when levels of biliverdin are higher in the female.

All spot on. The blue-green color in the eggs of these birds comes from biliverdin which, as Matthew Johnson pointed out, is derived from hemoglobin. Levels of biliverdin are higher in healthy females, and tend to fall off with each successive brood over the summer.

Congratulations again to Cheri, Kirsten, Liz, Matthew and Mike Holtz for correctly identifying these eggs, and another shout-out to Maren for all the great insights.

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This is Not an Evaluation

posted May 22, 2020, 9:16 PM by Jonathan Poppele   [ updated May 22, 2020, 9:33 PM ]

Over this Memorial Day Weekend, we were scheduled to host Minnesota's first ever Track & Sign Specialist Evaluation. With the eval postponed, we are running "This is Not an Evaluation" in it's place.

This is Not an Evaluation is now live. To view the questions and submit answers, follow this link to the Google Form.

To participate in the Zoom debrief at 4:00 on Sunday afternoon, follow this link.

The questions are rendered in photographs and presented in the style of a CyberTracker Track & Sign Evaluation. In the spirit of the a Specialist Evaluation, most of these questions are roughly comparable to 3-point CyberTracker questions. There are a total of 43 questions, which is about the number that might get asked on the first day of a two-day Track & Sign Evaluation. The questions all come from Ft. Snelling State Park and all of the photographs were taken on Thursday, May 22.

You are welcome to head out to Ft. Snelling and take a look at the questions for yourself. Most of the questions are quite close together, and most should be easily accessible. Depending on rain and changes in water level, everything should look pretty much the same when you read this as it did when the photos were taken.

Please note, however, that the questions are not all marked very clearly. I could not find my flags when I headed to the park to scout--so tracks are marked only with circles and popsicle sticks and some sign are not marked at all. To help you navigate to the questions, I have put together this Google Map, which shows the location of each question to within a few meters. It should be sufficient to find at least most of them.

Please enjoy. And remember, This is Not an Evaluation.

May 2020 Natural Mystery

posted May 10, 2020, 12:39 PM by Jonathan Poppele   [ updated May 10, 2020, 12:40 PM ]

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April 2020 Natural Mystery Answered

posted May 9, 2020, 7:28 PM by Jonathan Poppele   [ updated May 11, 2020, 10:02 AM ]

YouTube Video

Last month, we tried out an audio mystery for the first time. It proved challenging. Congratulations to Mike Holtz, who was the sole person to send in a correct answer. Like others who submitted answers, Mike began trying to identify this as a bird call. But as he and several others realized, this is not the call of a bird. It is the call from which this animal gets one of its more colorful common names.

This is the call of the largest burrowing squirrel in the east, Marmota monax, know colloquially as a woodchuck, a groundhog, and across Appalachia as a whistle pig for this high-pitched alarm call.

In the Peterson Reference Guide Behavior of North American Mammals, Elbroch and Rinehart note that the repetition rate of the calls expresses the level of danger. A single call notes a minor risk, while frequent repetition indicates high risk.

Kirsten Welge, who correctly guessed that this was the vocalization of some kind of squirrel, identified the following features of the call which she used to essentially rule out birds as possibilities:
  • High volume (“robust”), 1 note “cheep” call
  • Clear tone -- no “static” or buzzing in the timbre
  • Interval of 5-9 seconds silence between notes
  • Short duration (<1 sec)
  • Pitch rises slightly over the call, less than a half-tone above the starting pitch

Maren Miller noted the similarity between these calls and the calls of Spring Peepers, but noted that:
"Spring Peepers tend to chirp on a slightly lower pitch than the A flat/A natural pitch in this recording and I'm not necessarily hearing obvious pond, lake, or wetland background sounds that I would expected to hear in a Spring Peeper's habitat."

But it was Mike Holtz who pulled this sound out of his memory banks and posted the sole correct answer. Congratulations, Mike!

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Carlos Avery Story of the Day

posted Apr 14, 2020, 12:39 PM by Jonathan Poppele   [ updated Apr 14, 2020, 1:00 PM ]

Our Cedar Creek Spring Wildlife Survey was scheduled to take place on Saturday, April 4. But social distancing guidelines in place, and Cedar Creek shut down all non-essential activities, it was time to improvise. We moved the survey to the nearby Carlos Avery Wildlife Management Area; invited trackers to head out on their own and share observations through iNaturalist; then gathered for a Zoom conference call to share stories and answer each other's questions. It was our first dispersed, asynchronous tracking event--and it was a tremendous success. Here are a few highlights from the weekend.

Our trackers got out on the landscape on both Saturday and Sunday, recording 86 observations of 34 different species including a dozen species of mammals. You can see all of our observations from the weekend here, and weigh in with your own identifications. The weather could not have been better, with sunny skies and temperatures climbing into the mid 50s. A rain system had moved through on Friday, washing the sandy roads clear. Despite the perfect substrate, animals hadn't had much time to move around since the rain ended and we recorded only a few clear mammal tracks like these crisp deer tracks. Some other tracks were made as the rain was ending, such as these mink tracks that showed up as patches of dry sand on top of the road. We couldn't see any details, but the transverse lope track pattern is clearly evident. The habitat, size, and details of the track pattern all point to these being mink rather than skunk tracks.

The fine weather also brought out an unusually large number of dog walkers. By mid-day on Saturday, many of the most easily accessed roads were covered with the tracks of people and dogs, which made it quite challenging to identify the tracks of wild canines. Some of the domestic dog tracks we found closely resembled coyote tracks, while some others were remarkably wolf-like. Despite the confounding tracks, we found solid evidence of wild canines on the landscape. In addition to fox track, we found scat from both fox and coyote. The scat confirmed the presence not only of fox and coyote, but of meadow vole and eastern cottontail as well. We found the partial jaw bone of a meadow vole in a fox scat, and the partial jaw bone of an eastern cottontail in a mass of fur and bone fragments. We didn't reach a consensus on what the cottontail jaw came from, and invite you to weigh in!

Our trackers also identified the presence of a variety of birds from their tracks, sign, calls, live sightings, or from their carcasses. Our trackers recorded tracks of turkey, sandhill crane, and mourning dove; signs of woodpecker activity; spotted migrating songbirds, cranes, waterfowl and raptors including this Northern Harrier; and even found the almost completely intact cacrass of a barred owl (check out the feet!). The trackers that found the owl carcass also found the mostly intact carcasses of a common goldeneye and of a coyote.

The wetland habitat and spring weather also offered a background chorus of frog songs, and we were able to capture recordings of wood frog, boreal chorus frog, and spring peeper, as well as photograph some wood frogs.

At the end of the day on Sunday, we gathered together for a Zoom conference call to share what we found. The Zoom platform allowed us to share pictures, audio recordings, maps, and our iNaturalist observations as we shared stories, asked questions, consulted guidebooks and puzzled through a few things together.

A huge thanks to everyone who participated in our first dispersed tracking survey. For a first time trying out this format and these technologies, it was a smashing success. Which is great, because we expect that our next few tracking club weekends and our next Cedar Creek survey will follow a similar format.

June 13 was the date for our Spring Survey at Cedar Creek. We plan to run an event similar to this one. Mark your calendars. We may even be able to get a couple of lead trackers back on the landscape at Cedar Creek as part of the ongoing wolf monitoring there. Stay tuned!

April 2020 Natural Mystery

posted Apr 13, 2020, 3:39 PM by Jonathan Poppele   [ updated Apr 14, 2020, 1:17 PM ]

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Stay Home Minnesota Challenge & Sit Spot Buddy Calls

posted Apr 13, 2020, 3:37 PM by Jonathan Poppele   [ updated Apr 14, 2020, 10:47 AM ]

by Kirsten Welge

Several years ago, a friend and I wanted to improve our wildlife tracking and awareness skills.

We made a simple weekly commitment to one another: 
  • We each sat outside in our backyards for 20 minutes, at least a few times each week.
  • Then, we'd call each other each week for 15 minutes:
    • I'd share a highlight from our time outside ("There was a gray squirrel that was chewing on the cedar fence post!"). 
    • My friend listened with curiosity, then asked questions to help draw more of the experience from my memory. ("Interesting! What was it doing right before that? Did it rub its face also? ...What did that sign look like up close? Did you notice older markings like that? Are there markings on other posts? ...Does this squirrel live nearby?")
    • Then, we'd trade places - he'd describe his highlight, while I listened, then asked questions to feel into his experience. 
It's a simple practice, but profoundly supportive for deepening our awareness of what's around us. 

Three years and countless hours of observation later, my friend and I still have our weekly calls. It remains a place for each of us to share our stories of animal behavior to someone we know will be ready to catch it, and reflect back our enthusiasm and interest. 

If you'd like to try this out, you're invited to join the sit spot challenge - and you can try out a sit spot call with one of the Tracking Project volunteers.

Stay Home MN Sit Spot Challenge: Now through May 8
  • Pick a spot near your home. It should be convenient and easy to get to, like your backyard or a nearby park. 
  • Register for free on this Eventbrite link.
    • Use password MWTP
    • Submit your name, email, and phone number for a sit spot buddy
    • We'll pair you up as folks sign up
  • Get in touch with your buddy and pick a good time for a 15 minute weekly call.
  • Sit at your sit spot for at least 20 minutes, at least three days a week. Notice what shows up while you sit: weather, sounds, your reactions, animal behavior...
  • On your weekly call: 
    • Share something you're feeling gratitude for. 
    • Then, take turns sharing a highlight and questions with your buddy. 
    • As your buddy shares her highlights, listen deeply, then reflect back what you hear - asking questions with curiosity.
    • Close with thanks.

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