More on lichens

The Nature of PEI by Gary Schneider

Hammered Sheild Lichen

About a year ago I wrote a column about lichens—that strange family of interesting organisms that are neither plant nor animal.  

Lichens are certainly oddities, being neither plant nor animal. They are composites made up of a non-photosynthesizing fungus and one or more organisms that are able to photosynthesize, such as algae or certain types of bacteria.

They’re a strange family, and since we generally don’t eat them, or propagate them, or harvest them for fuel, we take them for granted. But as with many things in nature, we can’t really get excited, or even interested, in something if we have no understanding of it. I was recently out with friends on a bird walk, when one of them suggested that we learn more about lichens. While some can be a bit difficult to identify, lichens—unlike birds—do not flit around and generally do not change their appearance during the year. Anyone who has ever tried to identify one of the “confusing fall warblers” will know exactly what I mean.

Learning how to identify flora or fauna can sometimes be intimidating. There are so many clues to look for that you might feel overwhelmed and that you’ll never be able to learn anything.  Which is rubbish. I have no formal training in anything related to natural history, and if I can learn to tell a Black-capped Chickadee from a Boreal Chickadee, or a Balsam Fir from an Eastern Hemlock, then anyone can.  

So let’s look at one simple example of a lichen.

The photo above is of a Hammered Shield Lichen. First of all, lichens often have interesting and intriguing names. “Hammered Shield” is very descriptive, but so are “Old Man’s Beard” (the long, stringy lichen hanging throughout PEI woodlands) and “British Soldier Lichen” (small lichens with a bright red cap). Want more? How about “Bushy Beard Lichen” or “Pink Earth Lichen”—whoever gets to name these species must have a ball.

But back to the Hammered Shield Lichen. It is one that you will find growing in a wide variety of habitats. I’ll often find it on fence posts, wooden shingles, and occasionally on rocks but it more commonly grows on trees in our forests. It is a small foliose or “leafy” lichen, with a surface that is uneven, giving it an indented or hammered appearance. The colour ranges from silvery grey to light green, sometimes with a hint of blue.  

When I first started finding nests of Ruby-throated Hummingbirds, I was a bit surprised that they were made up of spider webs on the inside and Hammered Shield Lichens on the outside. Knowing next to nothing about lichens, I assumed that it was just a convenient building material, growing throughout the forest.

Then, as I learned more—enough to become dangerous, as they say—I thought it might have something to do with the antiseptic properties that many lichens are known to contain. A recent article from The Ohio Cardinal that a friend sent me probably has a more valid reason. The authors of the report studied the nests of Ruby-throated Hummingbirds and Blue-grey Gnatcatchers and found that the lichens are most likely used to camouflage the nests. The small nests are perched on branches and the lichens help keep them hidden from the eyes of hungry predators.

As we all learn more about nature, one thing clearly stands out—that we are just scratching the surface of how complicated and interconnected things are. Fortunately, the accumulation of knowledge can be a very enjoyable experience.