I've long had a special interest in the sleeping habits of small birds. In fact, as you'll know if you read the article I published here back in September 2008*, I've covered this issue before. In that article, I noted that at least some passerines secrete themselves away in crevices or thick foliage. I first became really interested in this subject after making one of my greatest natural history 'discoveries': a sleeping Blue tit Cyanistes caeruleus that I encountered while it was tucked deep beneath the broken bark of a tree, just the tip of its tail betraying its presence. I didn't have a camera with me at the time. And, yes, I (and a colleague) were creeping around in the woods, at night.
* I frequently find myself regarding an article as 'recent'. On finding it online, I'm then consistently surprised when it's actually, like, three years old or so.
Other passerines form huddles inside tree holes and nest boxes: cases where Eurasian wrens Troglodytes troglodytes pack tightly into nest boxes and hirundine mud nests during the winter are well known, with the record being 63 individuals found in the same box. Unsurprisingly, birds at the bottom of such deep piles sometimes suffocate to death. House sparrows Passer domesticus have been reported to use streetlight interiors as winter roosting locations. Still other species roost on branches, but typically huddled close to friends or relatives and mostly hidden by surrounding foliage.
There are also passerine species that roost in caves (Diamond 1983), and then there's the fact that various tits, kinglets, buntings and others excavate and roost in snow burrows (e.g., Bagg 1943, LagerstrÃ¶m 1979, Helle 1980). Then there are species that sleep in nests. Some species sleep on their nests prior to the laying of their first egg (e.g., phoebes) but don't use the nest as a roost at other times of the year. The Curved-billed thrasher Toxostoma curvirostre [shown here, by Peter Wallack, from wikipedia], which builds its nest in thorny cacti, is apparently unique in sleeping on its open-topped nest outside of the nesting season (Skutch 1960a).
Other passerines that sleep in their nests outside the nesting season use covered nests. The use of such nests year-round is particularly well known for various tyrant flycatchers (e.g., Sulphur-rumped flycatcher Myiobius sulphureipygius) (Skutch 1989). In some areas, the use of covered nests as roost sites is probably opportunistic and not really a necessity, but in others it may be necessary if the birds are to survive through the cold night (Skutch 1960a, Merola-Zwartjes 1998). Some passerines (e.g., Eye-ringed flatbill Rhynchocyclus brevirostris, House sparrow, Bananaquit Coereba flaveola, various wrens) are known to construct special dormitory nests or roost nests (Skutch 1960a, b, Jansen 1983, Merola-Zwartjes 1998). [Costa Rican bananaquit nest shown here by Steven G. Johnson, from wikipedia].
The immediate surrounds of my house are home to a small colony of House sparrows. It can't be easy for such birds to persist in sub-urban habitats given the committed efforts of local humans to remove all and any foliage. Anyway, my interest in passerine sleeping habits got me wondering: where do my sparrows go at night? I became determined to find out.
As I've spent the last year or so discovering, determining exactly where small birds go as the sun starts to go down is surprisingly difficult. On several occasions I stayed out, watching the birds and waiting to see exactly where they go during dusk. This didn't work; they simply flew around the building and out of sight. Given that they nest in my neighbour's roof (but not mine), could they roost in my roof? I crept, as quietly as possible, hidden in darkness, deep into the darkest recesses of the loft one night, armed only with a torch and a camera. Small apertures around one of the gables allow birds to enter the roof in a particularly inaccessible region. Turning the torch on only when I'd reached said inaccessible region, I found a lot of grass and feathers that perhaps indicated a previous nesting effort. But, alas, no sleeping birds.
Then, some months later, I began to notice that small birds would sometimes fly off into the darkness whenever I left the house (at night) via the front door. I never got to see them, only hear them. Associated droppings [see adjacent pic] revealed that an area right above the front door was being used as a roost site, and apparently on a regular (probably nightly) basis. To cut a very long story short, I eventually learnt that some of the local sparrows were spending their nights under the porch roof over my front door, perched on dead jasmine branches and pressed right up under the slanting roof. At times, at least three sparrows (one male and two females) shared the roost. I became determined to photograph them while minimising disturbance; alas, photographing them without one, two or all of them flying away proved just about impossible. The photos you see here are the result. Finding sparrows roosting under the roof of my front porch isn't exactly a revelatory scientific discovery, and I don't plan to write it up for attempted publication in a technical journal. But it's a very satisfying personal little discovery.
The end of the story is somewhat sad, however. For various reasons I had to remove a dead tree from the garden adjacent to the porch. This was several metres away from the porch, but it seems that its position still provided cover or protection of some sort. With the tree removed, the sparrows moved on. They roost somewhere else now, but where I do not know... Sleep well, little sparrows. [UPDATE: I was wrong, the sparrows are still using the site as a roost. Good, I feel less guilty.]
Thanks to Dartian for digging out the snow-roosting citations.
PS - in totally unconnected news, I just joined twitter. Find me at TetZoo.
For previous articles on sleep, roosting, nesting and other connected aspects of bird behaviour, see...
- Dead baby birds: why here, why now?
- Why can't my readers be dumber? Or: replica owls
- A stork in ice and snow
- Sleep behaviour and sleep postures
- Why do some owls have ear tufts?
- Raptor makes killing in university grounds
- The pigeon in the fireplace
Refs - -
Bagg, A. M. 1943. Snow buntings burrowing into snowdrifts. The Auk 60, 445.
Diamond, J. 1983. Melampitta gigantea: possible relation between feather structure and underground roosting habits. Condor 85, 89-91.
Helle, P. 1980. A great tit Parus major roosting in snow. Ornis Fennica 57, 175-176.
Jansen, R. R. 1983. House Sparrows build roost nests. The Loon 55, 64-65.
LagerstrÃ¶m, M. 1979. Goldcrests Regulus regulus roosting in the snow. Ornis Fennica 56, 170-172.
Merola-Zwartjes, M. (1998). Metabolic rate, temperature regulation, and the energetic implications of roost nests in the Bananaquit (Coereba flaveola). The Auk, 115, 780-786
Skutch, A. F. 1960a. The nest as a dormitory. Ibis 103, 50-70.
- . 1960b. Life Histories of Central American Birds II: Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. (Pacific Coast Avifauna No. 34). Cooper Ornithological Society: Berkeley.
- . 1989. Birds Asleep. University of Texas Press, Austin.
What I liked to know is what you were doing sneaking around with a colleague in the middle of the woods at night. Sounds like something from the x-files.
what you were doing sneaking around with a colleague in the middle of the woods at night.
Their parents were in the house and they needed someplace to, uh, roost.
No no no, you have it all wrong. 'Colleague' is not a code word for 'girlfriend'. I and a colleague were looking for big cat field sign. Now you know.
So, 'looking for big cat field signs' is what it's called nowadays, huh? No wonder I'm having no luck.
As that 'Colleague', I can back Darren up on that one! I may have an out-of focus shot of the bluetit somewhere. I'll try and dig it out. As well as looking for field signs, there was also a fair amount of shining powerful torches around a lake but alas no eye-shine...
I tend not to do much birding at night -- it's dark, you know. But lately I've seen a male robin (that's Turdus migratorius in case you were confused) sitting in a nest in the daytime, looking for all the world as if he's sitting on eggs. Haven't seen the female at all so far. Maybe he's delusional?
And hey, when did you started calling English wrens "winter wren"? Let's remember that the species has been split. Winter wrens are now T. hiemalis, and they live only in eastern North America. I get T. pacificus, and you still have T. troglodytes. Or so declares the AOU.
You better be careful Darren. You're getting awfully close to earning the title of professional cryptozoologist.
Aww, crappit (comment 6: wren taxonomy). First that incident with giant tortoises, now this. Those who care, the paper concerned is...
Chesser, R. T., Banks, R. C., Barker, F. K., Cicero, C., Dunn, J. L., Kratter, A. W., Lovette, I. J. Rasmussen, P. C. Remsen, J. V., Rising, J. D., Stotz, D. F. & Winker, K. 2010. Fifty-first supplement to the American Ornithologists' Union check-list of North American birds. The Auk 127, 726-744.
I live in Southern Ontario. Judging by the sound just before sunset in urban and semi-urban areas, large flocks of house sparrows roost in ivy growing up against walls and in dense ornamental cedar trees.
[from Darren: sorry, delayed by spam filter]
In late January on a sunny winter day I was driving by a snow-covered field where a number of snow buntings and horned larks were roosting partially buried in snow. It makes sense for these species who are at home in a treeless barren landscape. Here are several photos: http://onejackdawbirding.blogspot.com/2011/01/horned-larks-and-snow-bun…
Could you let us know how to call the European wren now?
[from Darren: sorry, delayed by spam filter]
I lived two years in the Amazon rain forest, working as a birding guide and general guide. Sometimes we would go out at night to look for frogs, snakes, katydids, or nocturnal mammals. On several occasions I ran into small colorful canopy passerines (e.g. honeycreepers) sleeping at about eye level under dense foliage. These birds almost never are seen during the day in the understory of the rainforest. Other birds sometimes slept on skinny, very open horizontal branches, with no shelter. We had canopy towers where I worked, and from up there at dusk we sometimes noticed numerous White-browed Purpletufts lining up in a row to sleep on a thin leafless branch sticking up above the forest canopy.
But my favorite sleep-sighting happened during the day. I was with birding guide John Arvin and his group of birders around noon on a hot sunny day in the forest. Tropical forest birds always seem hard to find at mid-day in the heat. Knowing this, most birders in the tropics don't even bother to go out at mid-day, preferring to take a siesta instead. But there we were, and of course no birds in sight. Some bored person was randomly scoping the canopy, and he managed to spot a sleeping bird! Then, looking around more, we found lots of sleeping birds up in the canopy in that area. They were mostly colorful tanagers, of many species. A whole mixed flock was taking a siesta in the canopy above us.
There being only one wren species in all of Eurasia (so far as we now know), it's usually called just "wren" by the locals. (Though I understand some of them have their own, different words; why in some countries they have different words for everything -- don't know how they all understand each other.) But the official name -- again according to the AOU -- is "Eurasian wren".
As that 'Colleague', I can back Darren up on that one! I may have an out-of focus shot of the bluetit somewhere. I'll try and dig it out.
So, nothing untoward going on, just a couple of blokes out at night, looking for tits.
I'll be you weren't alone.
On a recent trip to India, while looking for nightjars and frogmouths in the Western Ghats, one of the guides was very good at spotting things in trees in the dark - a skill which meant he pointed out a number of birds sleeping while perched on branches. I think we saw about seven sleeping birds, all perched in fairly dense twiggy large bushes or trees. Most were bulbuls, but one was a golden oriole. They all had their feathers fully puffed out, and their heads tucked in. What really struck me was that once we had seen the birds they seemed very obvious and vulnerable, but if we hadn't had a guide who was well tuned in finding them, I'm fairly sure we would have not have seen any of them, even though one of them was so close to the path I could have touched it (I didn't of course).
The guide also spotted a lovely bright green malabar pit viper in a tree.
I had some sparrows (I assume Passer domesticus) nesting in a cavity where one of my bedroom walls meets the roof. I plugged the hole eventually (with an old shirt, as it happens). I'm not opposed to birds generally, but I am not in favor of those that make annoying noises early in the morning and, let's be honest, sparrows have nothing to recommend themselves acoustically. I'd take Tyrannus verticalis, Quiscalus mexicanus (both common city birds here in southern New Mexico) over these obnoxious little Passer any day.
So, the short version is, I'm a pleasant-sounding-bird chauvinist and dispute the "somewhat sad" of the last paragraph. :-)
Some passerines (e.g., Eye-ringed flatbill Rhynchocyclus brevirostris, House sparrow, Bananaquit Coereba flaveola, various wrens) are known to construct special dormitory nests or roost nests
The verdin Auriparus flaviceps is another passerine species that builds separate roost nests.
Thanks to Dartian for digging out the snow-roosting citations.
Thanks for the acknowledgement.
Primeval season five has aired it's first episode. It's not on BBC America. Anyone know how to watch it in the states.
This reminds me of the poor birds in Arkansas and elsewhere, falling dead from the sky on New year's Eve, possible spooked by fireworks.