The Hidden Company That Trees Keep: Life from Treetops to Root Tips by James B Nardi is an illustrated adventure that dives deep into the creatures that call a tree home. With over 350 illustrations, you can be sure to discover incredible insights into the complexity of a tree’s life force. Common animals like birds and mammals are of course covered. But The Hidden Company of Trees goes into the minuscule: insects, spiders, and microscopic life that shelter in roots and leaves.
Trees, despite their size and stationary statures, can often be overlooked or at least underappreciated. As a birder, I can identify hundreds of birds by sight and many of these by sound alone. Yet when it comes to trees, I can claim only maybe twenty or more on a reliable basis. I hide in their shade on a hot summer day or hunker behind them during a blustery snowstorm. But many times I’m scouring their branches only to pursue a flitting warbler, cursing the leaves that keep my quarry hidden.
But of course, trees are vital to our ecosystems, their value almost without measure. Clean air, clean water, shelter and food for uncountable animals.
Some of the detailed information is more than a layperson may care to read thoroughly. The pages are textbook-worthy yet still readable, even if some parts are more likely to be skimmed.
Chapter 1 – The Many Forms and Functions of a Tree’s Companions
The diversity of small critters found in trees (and elsewhere) is mind-boggling. Nardi catalogues the many families of arthropod allies: wasps, flies, hornets, true bugs, beetles, mites, lacewings, spiders, etc. The sheer numbers of species of each and the likelihood of further discovers of many many thousands more is intriguing to say the least.
Then we get into the microbial allies. Trees need nitrogen and bacteria carries out nitrogen fixation in a symbiotic relationship. These microbes also “… produce hormones that stimulate tree growth and wound repair.”
Chapter 2 – Out On A Limb: Living on Leaves, Buds and Twigs
Caterpillars make up the most species of leaf feeders. Species wise, there are “157,000 moths and 18,000 butterflies”. Many of these caterpillars have such great camouflage (to look like the tree material or even bird droppings) they are difficult to find. The amount of life moving around and eating among the leaves, buds and twigs is really fascinating and rarely seen (at least by human eyes).
Walkingsticks may be one of the most inconspicuous yet obviously well-adapted insects for twigs. They have nearly perfect camouflage, yet in tropical forests they have more tools up their woody-looking sleeves. These “[flash] bright colors to startle intruders, [have secret] defensive repellents, or [adopt] threatening poses and [swing] legs equipped with sharp, penetrating spines.”
The section on gall makers was the most interesting part of this chapter. There are several families of insects that “make” galls including wasps, sawflies, midges, aphids, and mites. The wild thing is that these insects actually manipulate the tree into making the galls and do not make galls themselves. You’ve probably seen these “tree bumps” countless times and there is still a lot about galls that remain unknown.
Chapter 3 – Tapping a Tree’s Circulatory System
Think sap. This section is all about the animals, again mostly insects, that break into tree walls for the rich food source of sap. Yellow-bellied Sapsuckers (Sphyrapicus varius) make rows of holes that draw out sap. These beautiful woodpeckers slurp up the sap and gobble down the insects drawn to it. Squirrels and still more insects feast on this food source.
While the woodpecker gets top billing, there are numerous species of insect sapsuckers as well. These include lace bugs and stink bugs.
Chapter 4 – The World Between Bark and Heartwood
This chapter focuses the insects that benefit from feasting on the area beyond the bark (phloem). The trees can be living or dead, and these insects are literally eating wood. Beetles, ants and termites are but a few of the creatures that borrow through the bark, excavating tunnels in the process.
Lichens and mosses that grow on the bark provide their own “forest”, complete with wildly diverse insects. Lichens also provide nest-building materials for hummingbirds, vireos, and various flycatchers. Second-hand tree holes, made by woodpeckers, become home to a host of other animals, especially birds. The Great-Crested Flycatcher add a number of tree-based materials to their nest cavities but also shed snake skins. Science has yet to figure out why.
Chapter 5 – In the Company of Flowers and Fruits
Pollination nation. This section covers the ways trees reproduce through pollination. Insects play a crucial role in tree reproduction, but pollination also occurs simply by pollen blowing in the wind. Bees are most commonly thought of when it comes to pollination, and there are some 3,600 species found in North America. Of course, there are many other pollinators including butterflies, moths, bats, and birds.
Seed dispersal is how trees populate distant areas. Squirrels are pros at moving acorns and other tree nuts. Blue Jays and other members of the Corvid family as well as Acorn Woodpeckers help move a large number of nuts. And of course, these nuts have specific insects associated with them.
Chapter 6 – The World Beneath a Tree
This is the area that is probably least known to me and to science. Definitely for me. The amount of activity that goes on that is indivisible to us is humbling. And what these insects contribute to healthy tree life can not be understated.
The majority of what happens at the bottom of the tree involves the “decomposers”. Composed of many groups of bugs from beetles to millipedes, these eaters of the dead number in the tens of thousands of species. These numbers even include some butterfly caterpillars.
Chapter 7 – Observing Firsthand
This last chapter has some practical DIY ways to observe some of the insects in your own backyard. The author also simply encourages everyone to take the time to make observations. There is a huge assortment of fascinating creatures to be seen. Although if I set up a moth-attracting observation light, my wife might make me sleep outside.
While the illustrations are black and white pencil drawings, they are still highly detailed. Also included are six pages of color illustrations depicting fine details of some of the commonly found life forms on a tree. Dubbed LeafScape, BarkScape and RootScape, these artistic renderings feature creatures of the leaves, bark, and underground in the roots.
The Hidden Company That Trees Keep provides a great catalog of the various insect families that reside in trees. This catalog lists the number of known species and highlights some of the facts that make the group interesting. The amount of diversity, even among more commonly acquainted insect types is truly amazing.
There are so many nuggets of knowledge throughout The Hidden Company that any level of naturalist will be be left in awe.
Birdfreak.com received a review copy of The Hidden Company That Trees Keep: Life from Treetops to Root Tips from the publisher, Princeton University Press.