Brace yourselves folks, the end of summer is nigh. Are you clinging desperately to your t-shirts and shorts, your Aperol Spritzes, and your nearly-empty bottles of suncream? I’m sorry to say I’m not in that camp — I’m looking forward to a bit of a reprieve from the heat. I’m weird, my perfect time of year is the two weeks in October where it’s cool enough for a jacket but not a hat and gloves; when the leaves are changing colour and dancing in the autumn breeze. But if you’re not like me and you’re still holding on for dear life, then you’ll be able to learn a thing or two from the subject of today’s article. This month’s bird is the Eurasian/Common Treecreeper (Certhia familiaris), known as Snag as Gaeilge.
You take a step back to admire the towering conifer tree presiding over the bend in the dirt path. This was no manicured Sitka spruce, coddled in a monoculture farm, but a Scots pine with a wicked scar that splits its trunk in two. Undeterred, the tree continued growing, as if the laceration was but a small scratch. As you wonder about the injury — had it been a lightning strike? — a small piece of bark begins to move. You start, thinking a large bug must have crawled out from between the cracks. On closer inspection, you realise the mottled creature is a little bird with feathers patterned like an autumnal forest floor. Their tiny body is mounted on huge claws that grips the ridges of the bark and propels them upwards. As they turn, you spot a matching beak, curving downwards, and see the flash of a white tummy. The bird climbs, and climbs, until it hangs upside down from a branch; as unbothered by gravity as the tree is about its scar.
We love a weird bird, don’t we folks? And such a cutie too. Cutie … Certhia … you would think there was some relation there … but no. The name actually comes from Kerthios, a small, tree-dwelling bird described by Aristotle. Familiaris is, of course, the word for familiar or common. But there’s nothing familiar or common about treecreepers, certainly not about their Irish name anyway, whose etymology we actually don’t know. What we can tell you is that ‘snag’ is a word for a tree that’s got one root in the grave, or is already a dead tree standing. A standing deadwood, if you would. A tree without any leaves and whose branches are beginning to rot and tumble to the ground (mind your head). You may think them eyesores at best and hazards at worst, but they’re actually a vital part of a mature woodland ecosystem. As we mentioned in the woodpecker bird blog, snags are teeming with insects who like to munch away on the fetid bark. They act as a food source for birds like the treecreeper and woodpecker. But cavity nesting birds will also make a home in these old trees, as well as mammals like squirrels and pine martens.
The treecreeper is one such bird. We actually found the nest of the one who was living in the Scots pine behind a chunk of loose-but-still-attached-bark near the large split in the trunk. (I still wonder about that tree, oh to hear the tale of that battle.) Treecreepers are quite territorial, but fairly indifferent to human activity. Still, we only watched them for a little while before we left them to their climbing. We’ve also seen them in the National Botanic Gardens in Glasnevin, where all sorts of strange exotic trees are cultivated. You may have luck spotting them in a giant sequoia/redwood tree, whose wood is relatively soft and whose plentiful, flowing ridges make the perfect spot for treecreepers to nestle up in.
A treecreeper’s feathers are more suited to blending in with the bark of a Scots pine or an old oak than with the redwood’s. They’d be nigh impossible to spot if they didn’t always seem to be hop, skip, and jumping their way up a tree. They usually start at its base and work their way to the top, bit by bit, an inch at a time. When they reach the canopy, they will flit off to a new tree. With their small creeping movements, it wouldn’t be remiss of you to mistake them for a rodent or a large insect. Even their call is very high-pitched, like the chirping of a cricket. Here’s a shameless plug for ornithologist, sound recordist, and nature boy Seán Ronayne’s website, where you can read his lovely write up of the treecreeper and listen to that piercing peep.
Ironically, for a bird who is so akin to a little bug, treecreepers are insectivores. They use that needle of a beak to probe into the thick, juicy bark of trees and prod at the insects hidden underneath. Fun fact, wood ants happen to share the same habitat as this bird and also feed on invertebrates on the trunk. Finnish researchers found that where there had been ants, there were fewer arthropods, (animals with hard exoskeletons), and also, there were fewer male treecreepers. Could this be because the males typically hang out at the base of trunks compared to the females in the leafier tops, and that the ants couldn’t make their way that far up? Does correlation finally equal causation?
While we were in the Netherlands we spotted a Eurasian nuthatch, which is a bird some taxonomists place in a superfamily with treecreepers (and wrens and gnatcatchers). Interestingly, the nuthatch moves in the opposite direction to the treecreeper — starting high and working their way down. I wonder if they’d be so bothered by the ants, or if they would be satiated by the time they made their way to the bottom. Finnish researchers, get on it.
To expand a little more on their family, they belong to the wider treecreeper family (duh) but in English we tend to drop ‘Eurasian’ from their name because we only have the one type in Ireland and the UK. While abroad we spotted a couple of their cousins: the brown treecreeper in Canada and the short-toed treecreeper in the Netherlands. You’d be hard pressed to tell this trio apart, so it’s important to utilise location and song to help with identification (*cough* Seán Ronayne’s website *cough*).
The Eurasian treecreeper’s range extends from western Europe all the way over to Japan, where there’s overlap with others in the family, so ID’ing can be tough. We’re lucky here at home because they’re the only one found here, so we don’t really have to worry about misidentifying them. Our little guys are actually the Brittanica subspecies, but since the Irish treecreepers tend to be a touch darker, they may be a contender for the fifth official Irish subspecies. Keep your toenails crossed for them!
If you want to get out there and enjoy the last of these lazy hazy summer days, why not get yourself to a park and find a spot in the shade of a tree? To keep from dozing off, you can always try playing Where’s Wally? with a treecreeper; there’s sure to be one clinging to a tree, snapping up those insects to keep them from ruining your last few relaxing days.