Marking Trees

Merriam-Webster defines a tree blaze as “a mark made on a tree to show a trail,” most particularly “a mark made by chipping off a piece of the bark.” As a material practice, there is a long history of mark-making on trees, imparting scars that last but do not endanger the tree. It is practice of the surveyor, the forester and ranger, and, most simply, of people who move through the landscape.

By leaving a trace in the material of the tree, the maker signals intention and, possibly, layers of information. As an indicator, it projects information in our visual plane for our feet to follow—a design for the sighted and the upright. It heralds an organizing system, one point in a network of points that is sensible only in relation to its terrain.

BlazeThe placement and number of blazes on a tree are a further extrapolation of terrain and projected human uses:

i) the out-and-back or destination trail, which requires way finding in two directions;

​ii) a directional use trail, which guides use in a single direction; and

iii) a loop trail or closed circuit, which is uni-directional and does not revisit the same points.

In the word blaze are echoes of its verb forms—”to make conspicuously brilliant” and “to make conspicuous or public.” Conspicuously brilliant, the blaze is full of material force and interest as an alteration to the texture of the landscape. Conspicuous, it invites its own public to participate in an experiential narration.

Our habitats, their habitats

This slideshow requires JavaScript.

Types of Habitats for Squirrels on WashU Danforth Campus 

For Squirrels, there are basically two types of habitat. One is for food resource, and the other is for building nests or caves. Of course, the trees where they usually build nest also can provide food, but only the ones that are tall and strong enough with many natural caves can be the preferred options for squirrels to live in and have litters.

On WashU Danforth campus, there are around 4,000 trees in 160 species, where many of them can be our Eastern Gray Squirrels’ habitats.

For food resources, they can eat seeds or berries from walnut, pine, oak, cedar, hemlock, spruce, hawthorn, mulberry, hackberry, locust, locust, tulip, hickory, crabapple, pear, or even persimmon, paw paw or dogwood trees.

Impressively, according to No Nuts, No Problem: Squirrels Harvest Maple Syrup  by John Roach at National Geographic, squirrels even can also survive on maple sap.

For their ‘residential’ spaces, they prefer oak, walnut, hickory, beech, elm, tulip poplar or sometimes cottonwood.

You may notice some of the food resources for squirrels are also edible for us, such as crabapple (for jam), pear, persimmon, pawpaw, and mulberry, although we do not tend to eat them as there are way better options for us.

When we do not need these available food resources, we would like to see animals playing around on the trees which bring us joy. However, if they accidentally invade our habitats, such as starting to live on our attics, or disturb our construction activities, this mutually beneficial relationship will be one-sided broken by us, and leave other species very little options.

Definition of Habitat

In Oxford and Meriam-Webster dictionary, the word “habitat” basically has two common definitions – the place where animal or plants grow or live, or residential dwelling places for the human.

Is there a chance that these two concepts can positively intertwine? How do we share our common resources wisely enough to create a healthy urban environment, not only ecologically, but also respectfully? How do we “communicate” with squirrels despite they can not really talk in order to know their feelings about our disturbance? The Squirrel Relocation Service team will keep digging into this question.

How do we act in the ‘network mutualism’ between squirrels and human? (1)
Through tracking the scent, this squirrel in the alley successfully found the acorn he/she hid under the ground. But will all squirrels be smart enough to find food in disturbed habitats?



The alley is under construction for the upcoming carnival



‘Network mutualism’, a concept mentioned in Rod Barnett’s book “Emergence in Landscape Architecture”, where he describes the relationship between coyotes and human in Auburn as such.

“While coyotes do not prey on humans, the reverse is often true, so the human- coyote relationship, could be said to be that of a predator species to its prey. Even though humans do kill coyotes, they are not dependent on them for food.

Ecologically, therefore, their relationship might be seen as commensal, where one species, the coyote, benefits from the habitat created by urbanization, while the other, the human, is not affected in any significant way. Or it is more accurate to say that the two species are equally involved what is sometimes called a network mutualism.

The coyote population distributes itself throughout a space without borders or enclosure.

Organized by the rule of law, human Auburn is a static space defined by walls, enclosures and paths between enclosures, a division that nonhuman Auburn is continually redefining as a smooth continuum of “habitats”, “ecotones”, and “biotic communities”.

Just like these coyotes, we and squirrels also have this network mutualism, despite occasionally they go to people’s attics to live, and we human disturb their habitats by constructions, such as the one for the coming carnival.

When the land is stripped, some squirrels are still smart enough to find where they hid their food by smell, but it is doubtful that if all the squirrels are as smart as the one we filmed.

We all know animals’ habitats not only benefit themselves but bring us ecological diversity. However, the value of their habitats is beyond that. Their old habitats equal to “historic sites” in human societies, although may going through a faster pace of reconstruction. It is one part of the public history that documents the evolution of the human and non-human relationship.

As Rod Barnett says in his book: “Public space, may well, in fact, be the primary site of this encounter, if we extend the notion of the public to include nonhumans.”

So here is the question, how do we not disturb squirrels’ habitats while doing our necessary construction?

The first step might be, recognizing the public space is “public” for everyone, even beyond human.



Symbiosis of Squirrels and Pin Oaks


Check out the full image here

Timeline-02A deep relationship between squirrels and pin oaks are shown in our research as above. Even though pin oak is a fast growing tree, compared to squirrels, it has such a long life cycle. However, they work and live intimately together year after year, generation after generation and witnessing each other’s growth or even evolution in the long history of ecology.

Tree Time


How can we enter into thinking and seeing and imagining in tree time? What are the limits of detection these arboreal sensors operate within? How can we listen to particularly talkative tree rings? These were only some of the questions that Mike Stambaugh and his colleagues at the Missouri Tree Ring Lab introduced us to as we took a deep dive into the theory and practice of dendrochronology.

We held the world’s oldest oak specimen, learned of the process of cross dating, and my mind still swims at the worlds opening up in thinking landscape forensics. In mounting our One Tree cores, we have come to the conclusion that the trees are between 80 and 90 years old–putting their planting date likely sometime in the 1930’s. We will dive into the WashU yearbooks in the coming week to see if we might be able to corroborate this date which challenges some of our other diagnostic work.

Many thanks to all at Mizzou’s Tree Ring Lab for being such generous hosts!


“The wrongs done to trees, wrongs of every sort, are done in the darkness of ignorance and unbelief, for when the light comes, the heart of the people is always right.”

-John Muir

On-site Squirrel Cavity Studies

Cavity on Site

Cavity Activity Map

According to “What’s That Clump of Leaves?” by Art Shomo, there are two types of nests: tree cavity dens and leaf nests. The nest is at least 20 feet up to the tree,  and during winter, the squirrels move the nests from the outer branch to the main trunk to get more stable structures, by weaving twigs and compacted leaves together. Dens are good for keep squirrels’ body temperature and protect them better from extreme weather conditions, which are usually with 6 to 8 inches diameter. Oaks, beeches, elms and red maples are ideal trees for squirrels to build dens or nests. In the author’s study area West Virginia, gray squirrels prefer dens more than leaf nests.

On our site, there are many trees with possible cavities, especially the area where the red circle is at on the “Squirrels’ Cavity Location and Active Area” map. However, it is very hard to find a nest on our trees, which seems to be consistent with the result by other researchers as mentioned above. We remember during the winter time, there was one nest possibly on C3, as it is getting warm, the nest is gone. But the cavity is definitely a proof of how the squirrels are playing around and actually try to live in these oak trees, just like this photo is showing here on our tree C3:


How far can squirrels travel?

According to a test by United Exterminating Company to trap and track the squirrels through both using straight-line runs and zig-zag patterns to different areas and spray paint to mark them, it turns out:1- 2miles: squirrels don’t have any trouble getting back

1- 2miles: squirrels don’t have any trouble getting back

5-7 miles (with zig-zag pattern): returns were rare, 1 out of 15-20.

10-12 miles: Occasionally, there were squirrels returning back, but less than a half-dozen times

25 miles: only one surprising return

Conclusion: activity range is less than 5 mile. It is very rare for squirrels to go larger than 10 miles.

So the squirrels really can travel everywhere to search places to have fun and for food resources.

The Activity of Gathering


This was the order of human institutions: first the forests, after that the huts, then the villages, next the cities, and finally the academies.

–Giambattista Vico, The New Science

In his amazing book Forests: The Shadow of Civilization, author Robert Pogue Harrison writes that “Civil society comes into being through the activity of gathering.” He references Vico on the ordering and evolution of this gathering (above), and further cites him on the Latin word lex, or law:

First it must have meant a collection of acorns. Thence we believe is derived ilex, as it were illex, the oak (as certainly aquilex means collector of waters); for the oak produces the acorns by which the swine are drawn together. Lex was next a collection of vegetables, from which the latter were called legumina. Later on, at a time when vulgar letters had not yet been invested for writing down the laws, lex by a necessity of civil nature must have meant a collection of citizens, or the public parliament, so that the presence of the people was the lex, or “law.”… Finally, collecting letters, and making, as it were, a sheaf of them for each word, was called legere, reading.

%d bloggers like this: