|The Question: Hello, I can’t believe I’m even asking you this, but can an animal evolve shape-shifting abilities or is it completely fantasy?
Submitted by: Alexander, England
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It has been a while since I posted answers to questions, and I apologize for that. I’m hoping to get back into the swing of things over the next couple of weeks. And I thought I’d start with a quick review of a unique book, Tracks & Signs of Insects and Other Invertebrates, a Guide to North American Species by Charley Eiseman and Noah Charney. The book is comprised of 523 pages of photographs and descriptions of eggs, droppings, burrows, and more, on land, in water, and suspended in air. There are many guidebooks for North American insects, many books that will help you identify tracks and signs of mammals, and a fair number that will help you with birds, reptiles and amphibians. But for North America, at least, I don’t believe there is anything else like this book to help you identify the tracks and signs left all around us by insects and other invertebrates.
The book is organized by type of sign, with chapters such as Eggs, Cocoons, and Galls, and also by places to find signs, with chapters such as Signs on Twigs, Stems and Stemlike Structures and another that shows Signs on Rocks and Shells. As I leafed through the pages, I found myself making note to watch more carefully for various patterns and markings the next time I’m out in the woods, or even just out in the backyard. If you’re interested in the insects, spiders, worms and other tiny creatures that really run things on planet earth, you will find this book useful and fascinating.
One warning: if you’re easily creeped out, skip the chapter on parasitism. It’s fascinating and it shows a wide range of signs you can find that show how invertebrates parasitize each other – and how everyone gets parasitized by fungi – but on a tiny scale, it’s also pretty gruesome.
The book was published in 2010 by Stackpole Books. It won the 2010 National Outdoor Book Award and is for sale on Amazon and other book sites, or you can buy it directly from authors Eiseman and Charney’s Northern Naturalist website at http://www.northernnaturalists.com/invert_tracks.html. If you want to get a somewhat manic taste of the kinds of things this book covers, take a look at the videos on the Northern Naturalists homepage: http://www.northernnaturalists.com/.
Eiseman, C., Charney, N. (2010). Tracks & Signs of Insects and Other Invertebrates, a Guide to North American Species. Mechanicsburg, PA: Stackpole Books.
The Short Answer: These holes are classic foraging holes of the pileated woodpecker (Dryocopus pileatus), the largest woodpecker in North America (assuming Campephilus principalis, the ivory billed woodpecker, is extinct). The ones you found do look remarkably regular, as if made by a saw or a wood chisel. You must have an exceptionally neat woodpecker in your neighborhood. Carol Hartwig, a retired wildlife consultant who has studied pileated woodpeckers, says pileated woodpeckers often make square or rectangular holes. She speculates that the rectangular shape may be energy efficient. She also notes that the grain of western red cedar (Thuja plicata), which is what your tree trunk looks like, is particularly straight.
“The grain of western red cedar is so straight that when the woodpecker hammers with its bill into the trunk, large, straight pieces are excavated. This results in very square corners and a very clean rectangular shape. Their nest cavities are beautifully oval, however, so they are capable of making different shapes depending on the purpose and the type of wood they are excavating.”
Your holes are far too close to the ground to be attempts to build a nest cavity. More likely, the bird was looking for insects, its main source of food. Ants and termites are favorites, and beetle larvae and other tasty insect treats would be on the menu as well. Given the size of the hole, I’m guessing the bird was having good luck.
Tree Holes are in Demand: One group of researchers observing the nests of pileated woodpeckers saw wood ducks (Aix sponsa) repeatedly attempt to steal a choice pileated woodpecker cavity. The nest already contained three hatched chicks and the male woodpecker remained on guard a short distance away. When a wood duck hen would attempt to fly to the nest tree, the male woodpecker would intercept her and prevent her from going inside. However, the researchers noted one time when the wood duck hen entered the nest as the woodpeckers were off foraging and another time when the duck was so quick to the tree, the male woodpecker was caught off guard. In both instances, the male woodpecker entered the nest, a fight ensued, and the woodpecker eventually expelled the wood duck hen and retook his family’s nest. For animals that nest in tree cavities but can’t excavate their own, like the wood duck, the relatively large nest cavities of pileated woodpeckers are prime real estate.
Sources: Conner, RN, Shackelford, CE, Saenz, D, et al. (2001). Interactions between nesting pileated woodpeckers and wood ducks. The Wilson bulletin, 113(2), 250-253.
CONNER, RN, JONES, SD, & JONES, GD. (1994). Snag condition and woodpecker foraging ecology in a bottomland hardwood forest. The Wilson bulletin, 106(2), 242-257.
Hartwig, CL, Eastman, DS, & Harestad, AS. (2006). Characteristics of foraging sites and the use of structural elements by the pileated woodpecker (dryocopus pileatus) on southeastern vancouver island, british columbia, canada. Annales zoologici Fennici, 43(2), 186-197.
This is the coolest! Wildlife photographers put a camera on a remote control car and drove it into a pride of lions. The lions broke the car — no surprise there — but the resulting pictures are very cool. And for some reason watching the lions react to the car cracked me up.
I just read Peter Allison’s book Whatever You Do, Don’t Run: True Tales of a Botswana Safari Guide, and greatly enjoyed it. The stories of Allison’s days as an African safari guide are often funny, sometimes touching, and always interesting about the wildlife of southern Africa.
It’s a fun, breezy read, and for people who are interested in wildlife, or who dream of someday going to Africa on safari, I highly recommend it.