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Sunbathing birds

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Sunbathing passerines. Top to bottom: Greater necklacked laughingthrush, Snowy-crowned robin-chat, and Superb starling. Starling photo by Michael O’Sullivan. Click to enlarge!

A few weeks ago, I and the family visited Birdworld in Alice Holt Forest, Surrey (UK). We had a great time and saw a lot of neat birds. It was a scorching hot, very sunny day, and the reason I’m writing this article is because I became particularly interested in the many, many sunbathing birds I saw that day. Don’t get me wrong, I’m extremely familiar with the fact that birds often engage in sunbathing behaviour, and indeed I’ve often watched Blackbirds Turdus merula and other familiar species do it in my own garden. But I’ve never seen so many species, belonging to so many diverse groups, sunbathing within such a short span of time. I took photos where possible, so consider this article a brief guide to sunbathing postures in birds.

To those academically interested, note that there’s a fairly extensive literature on sunbathing in birds and on the groups that practise it, on the postures they adopt, and on the function it might have (e.g., Hauser 1957, Kennedy 1969, Horsfall 1984, Simmons 1986).

Male Elliot’s pheasant or Bar-backed pheasant Syrmaticus ellioti, a native of wooded hillside habitats in SE China.

We’ll start with gallinaceous birds. The adjacent photo shows a sunbathing Elliot’s pheasant or Bar-backed pheasant Syrmaticus ellioti with one wing slightly fanned out and the tail slightly spread. I’ve seen guans, domestic chickens and other gamebirds do the same sort of thing, and this got me wondering if waterfowl (close relatives of gamebirds within the clade Galloanserae) do the same thing – I’ve never seen a sunbathing duck or swan. Having said that, geese at least (especially Canada geese Branta canadensis) sometimes sit in the sun with the wings hanging more to the sides than usual, thereby exposing the back to the sun. Various photos online labelled as showing ‘sunbathing’ ducks actually just shows ducks sitting in the sun, wings folded, in the normal resting pose. Swans sometimes swim along with one foot out of the water, toes stretched so that the webbing is fully exposed, and I’ve heard it said that this is to do with shedding heat, not collecting it. But, so far as I can tell, waterfowl don’t seem to stretch their wings out to ‘collect’ warmth – does anyone know otherwise? (if you’re thinking about the other members of Anseriformes – the screamers – let me give you a bit of advice and suggest that you don’t google ‘sunbathing screamer’).

Secretarybird Sagittarius serpentarius sunbathing. These long-legged raptors really are raptors, and not close kin of seriemas (mind you, you don't hear that idea at all these days).

I was particularly happy to see this sunbathing Secretarybird Sagittarius serpentarius on its belly, wings fanned out to the side. It mostly kept both wings fanned out, but sometimes folded one wing away. Various hawk, eagle, vulture and condor species are well known for standing erect while facing the warmth of the sun and either holding their wings outstretched, or standing with their wings drooped to the sides in what’s known as a delta-winged posture. I’ve previously (Tet Zoo ver 2) used pictures of Andean condor Vultur gryphus and Lappet-faced vulture Torgos tracheliotos doing exactly this.

Andean condor Vultur gryphus (l), photo by Markus Bühler, and Lappet-faced vulture Torgos tracheliotos (r) in characteristic sunbathing postures.

Certain storks and herons also adopt delta-winged and spread-eagle poses (Curry-Lindahl 1970, Kahl 1971): the adjacent image (kindly provided by Lars Thomas) shows a Grey heron Ardea cinerea. Poses that involve holding the wings out don’t necessarily show that the bird is trying to warm itself: they might also be used when the bird is trying to lose heat, dry its feathers, show off to rivals, or shade its eggs or babies. Cormorants, pelicans, anhingas and others are well known for adopting spread-winged postures when they need to warm up, cool down, or dry their feathers.

Grebes sunbathe in a distinctive posture where the rump is raised toward the sun while the wings and feathers on the back are held slightly raised. This helps expose a dark-skinned patch on the bird’s back (the feather bases are also dark here) that’s presumably good at absorbing heat (Storer et al. 1976). Even white- or pale-feathered mutant grebes retain this dark patch, suggesting that it’s physiologically important (Jehl 1985).

Based on my massive sample size (n = 2), it seems that pigeons like to recline on their sides during sunbathing, with the wing on the opposite site raised up such that the underwing is fully exposed to the sun. In fact, this is known to be typical for pigeons and doves (Hauser 1957, Nicolai 1962, Johnston 1965). The bird shown in the adjacent photo – a Mindanao bleeding-heart dove Gallicolumba crinigera – stayed on its right side for a while, sometimes with its left wing raised and sometimes with the wing held loosely at its side. The Pink pigeon Nesoenas mayeri shown below also reclined with one wing raised (this time, reclining on its left side), but also fanned the right wing out flat on the ground. It fanned its tail feathers out at the same time.

Obliging Pink pigeon Nesoenas mayeri, in two different sunbathing poses. Loved by everyone who reads Gerald Durrell.

Sunbathing passerines of all kinds typically lie on their fronts, on the ground, their wings and tails spread out as much as possible. I photographed a Greater necklacked laughingthrush Garrulax pectoralis and Snowy-crowned robin-chat Cossypha niveicapilla while they were sunbathing (see images at very top of article); Michael O’Sullivan also kindly provided the image, taken at London Zoo, showing sunbathing in a Superb starling Lamprotornis superbus. Note that the robin-chat has raised the feathers on its back and rump, and across much of its body in fact. Spread-eagled postures like this are seen elsewhere in bee-eaters and other groups.

Some birds will sunbathe while perched, fanning one or both of their wings while sitting well up off the ground. This Trumpeter hornbill Bycanistes bucinator spent a while with both of its wings fanned out to side.

The birds shown here are all in alert poses, even when lying recumbent. That is, their heads are up and they’re keeping an eye on the surroundings. It’s been noted in the literature that sunbathing is frequently risky: the birds are in a prone position and are relatively incautious and easy to approach. There are some indications that birds know this, in cases preventing (or trying to prevent) their mates from engaging in sunbathing (Kilham 1981). If birds are in a particularly safe location they’ll sometimes rest the head on the ground. A particularly neat image of a Peregrine Falco peregrinus doing exactly this – it was photographed on its nest, many metres above the ground – can be seen here.

Everyone familiar with birds knows that sunbathing behaviour is common, widespread and easy to spot, and various authors have wondered what function it might serve (e.g., Goodwin 1967, Kennedy 1968, Mueller 1972, Horsfall 1984). Some passerines have been seen sunbathing when already heat-stressed (they were gaping, projecting their tongues, and reclining in areas where the ambient temperatures were already higher than those generally thought to be ideal for small birds) (Blem & Blem 1992). This supports ideas that sunbathing is sometimes carried out for some function unrelated to the need to warm the body: maybe it helps dislodge parasites, helps maintain feather condition (the easiest way to straighten a slightly damaged feather is to hold it in a stream of hot air), or helps ease discomfort associated with moulting.

This article falls well short of picturing sunbathing postures seen across Aves but, regardless, I hope you found it interesting. And I’m very interested if anyone has any additional accounts, or images, that they’d like to share.

Another Grey heron, courtesy of Lars Thomas.

For previous Tet Zoo articles on various bits of poorly known behaviour practised by birds, see…

Refs – -

Blem, C. R. & Blem, L. B. 1992. Some observations of sunbathing in swallows. Journal of Field Ornithology 63, 53-56.

Curry-Lindahl, K. 1970. Spread-wing postures in Pelecaniformes and Ciconiiformes. The Auk 87, 371-372 .

Goodwin, D. 1967. Some possible functions of sun-bathing in birds. British Birds 60, 363-364.

Hauser, D. 1957. Some observations on sunbathing in birds. Wilson Bulletin 69, 78-90.

Horsfall, J. 1984. Sunbathing: is it for the birds? New Scientist 103 (1420), 28-31.

Jehl, J. R. 1985. Leucism in Eared Grebes in western North America. The Condor 87, 439-441.

Johnston, R. F. 1965. Sunbathing by birds. The Emu 64, 325-326.

Kahl, M. P. 1971. Spread-wing postures and their possible functions in the Ciconiidae. The Auk 88, 715-722.

Kilham, L. 1981. Sunbathing Vermilion-crowned flycatchers repulse mates. The Auk 98, 839.

Kennedy, R. J. 1968. The role of sunbathing in birds. British Birds 61, 320-332.

- . 1969. Sunbathing behaviour of birds. British Birds 62, 249-258

Mueller, H. C. 1972. Sunbathing in birds. Zeitschrift für Tierpsychologie 30, 253-258.

Nicolai, J. 1962. Uber Regen-, Sonnen- und Staubbaden bei Tauben (Columbidae). Journal of Ornithology 103, 125-139.

Simmons, K. E. L. 1986. The Sunning Behaviour of Birds. Short Run Press, Ltd., Exeter (UK).

Storer, R. W., Siegfried, W. R. & Kinahan, J. 1976. Sunbathing in grebes. Living Bird 15, 45-58.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. glynyoung 5:59 am 08/1/2011

    I don’t think any wildfowl sunbathe in typical bird-like manner. They may doze in sun but never spread their wings. Interestingly Thalassornis and swans can put their large, black, feet on their back and spread toes/webbing. This allows birds on water to warm up through ‘solar panels’!

    Link to this
  2. 2. DMA12 6:51 am 08/1/2011

    Apparently, Telegraph is not familiar with birds or sea monsters. They have an article from April of ’09 that treats it like a new discovery. I would link to it, but I still can’t figure out how to create links in the text.

    Link to this
  3. 3. ChasCPeterson 8:47 pm 08/1/2011

    Interesting. Of course, in a few cases it’s clear that sun-basking does have a thermoregulatory function; the classic case is the roadrunner (Ohmart and Lasiewski, Science 172:67-69).

    Funny: while hunting down that reference I found this one by Cade (1973; Condor 75:106-133:
    link to pdf). More photos and similar puzzlement about the obviously nonthermoregulatory cases.

    Link to this
  4. 4. Hai~Ren 9:32 pm 08/1/2011

    There are a number of interesting photos of various species of Southeast Asian birds sunbathing on the Bird Ecology Study Group blog. Go there and search for “sunning” and “sunbathing”.

    The birds for which this behaviour has been documented include storks, raptors, coucal, anhinga, bee-eaters, malkoha (a cuckoo), hornbills, and even an owl!

    Link to this
  5. 5. deang 11:49 pm 08/1/2011

    Where I live in central Texas, we have massive populations of Great-tailed Grackles (Quiscalus mexicanus), and I’ve often seen them sunbathing on lawns. They tend to do it in the reclining-on-their-side manner you note here for pigeons, usually with their mouths open. Sometimes several will stride out into the sun and do it at the same time, and they seem to distance themselves somewhat evenly from each other. I’ve seen them all tilt onto their sides, fluff out their side feathers, and open their mouths at once, almost in unison. It’s pretty funny.

    I also once watched a Carolina Wren (Thryothorus ludovicianus) sunbathe while perched in an Anacua tree (Ehretia anacua). It stretched its tiny body (about the size of an Anacua leaf) vertically and pointed its beak straight up, then leaned far to one side and puffed out its neck, side, and breast feathers, holding that position for a while before leaning far to the opposite side and repeating the procedure. It appeared to be getting a good stretch as well.

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  6. 6. naishd 6:47 am 08/2/2011

    Tet Zoo ver 2 typically received about 23 comments per article. Yet here we have four five. Huh. Thanks for comments though. Still no progress on open commenting. I am not happy.

    Darren

    Link to this
  7. 7. BilBy 8:32 am 08/2/2011

    It’s a pity that there are not more comments – TetZoo is made doubly interesting by the comments section. I also miss the side bar indicating which threads have had the latest comments. There is STILL comment action happening on TZVersionII.

    Link to this
  8. 8. sharpelynda 9:12 am 08/2/2011

    I hope the comment situation improves (always a fun part of your blog).
    Hey everyone: it’s easy to register here!

    One of my most amazing wildlife experiences involved sunning birds. I was in Kruger National Park and had stopped right in front of a group of about 30 or 40 marabou storks who were standing on a sand bar in the Sabie River. All these tall, heavy birds were facing the same direction (towards me), presumably to catch the morning sun, although it was currently overcast. Then, for no discernable reason, every one of them swept into a profound bow. In perfect unison, they all graciously bowed their heads low and slowly spread their wings out sideways, exactly like curtseying ladies. For a moment or two, I sat staring – utterly gob-smacked – as a large flock of birds paid me homage. Then I realised the sun had come out!

    Link to this
  9. 9. werehawk 3:01 pm 08/2/2011

    So that’s the Pink pigeon whose nests proved to be Gerald Durrell’s bane…Despite it being a few years since I read the book the scene as described by him still makes me start chuckling.

    Link to this
  10. 10. DunkTheBiscuit 3:22 pm 08/2/2011

    It’s a shame about the comments situation. I’ve always enjoyed the lively discussions that occurred. I’d comment more often if I had anything pertinent or intelligent enough, but the calibre of comments on Tet Zoo has always been rather intimidating! :P

    I cut my natural history teeth on Durrell’s books as a child, and I always enjoy being reminded of the success story that is the pink pigeon – sometimes conservation seems to have such a bleak future, it’s nice to know sometimes things go right.

    Link to this
  11. 11. Lou Jost 9:35 pm 08/2/2011

    My favorite bird artist, Raymond Harris Ching, made many exquisite paintings of sunning birds. I recommend bird-lovers look him up. His latest work is somewhat weird (women flying through the air alongside rather stiff birds), but his earlier watercolors and oils (pre-2000) are wonderful. He may not be well known to the public, but many of his fellow bird artists consider him one of the best ever.

    Also, I can testify that the tropical American tiger herons use the exact same sunning pose as the Gray Heron shown in the post.

    Link to this
  12. 12. Dartian 2:41 am 08/3/2011

    I like Tet Zoo more than I dislike registration, so here I am. But BilBy is right; whoever is is charge of these things over at SciAmBlogs, please introduce a sidebar that shows the latest comments ASAP!

    On-topic: Is lying on the belly like that, on the ground, really the typical sunbathing posture for the secretarybird? For a large, ground-living bird (especially one that lives on the predator-infested African savanna) that seems like a somewhat vulnerable position.

    Link to this
  13. 13. UK_wildlife 12:42 pm 08/3/2011

    I visited birdworld a couple of years ago (which reminds me, I must edit the photos form there!), and it was pretty good. My Gf’s dad however was disappointed, as in previous years they had many more birds.

    As for basking birds, I can’t say Ive seen wildfowl basking ever, mind you I’ve rarely seen any birds basking, at least in photographic range! I have very few photos of this behaviour.

    Link to this
  14. 14. Zoovolunteer 3:09 pm 08/3/2011

    According to the Mauritius Wildlife Foundation website, the pink pigeon population currrently stands at over 300 in five subpopulations. Not many,but there were only 12 in 1986

    Link to this
  15. 15. CFowler 7:27 pm 08/5/2011

    Like DunkTheBiscuit above I have rarely felt qualified to add to the discussion previously. I was wondering about non-thermoregulatory behavior yesterday when my terrier went from an 80 degree F environment straight out the back door to lie in the sun. Could the explanation be that it just feels good? I know if you give a parrot unlimited access to peanuts, they’ll gorge themselves past their nutritional need on the fatty goodness. One could say the same for me and chocolate chip cookies.

    Link to this
  16. 16. Stripey_cat 6:30 pm 08/7/2011

    I have fond memories of a falconry display where a small falcon (possibly a peregrine-merlin hybrid) who wasn’t good at mornings took off to the top of a marquee that was high enough to be in the sunlight, and stayed there sunning himself in classic heraldic eagle pose for a good ten minutes. The audience sympathised with him – it was a very chilly morning! (His handler definitely thought he was trying to warm himself up, and he was much more willing to cooperate at the lunchtime display.)

    Link to this
  17. 17. Tamara Henson 7:25 pm 08/11/2011

    I know it’s late but it’s not often that one of Darren’s posts corresponds to my hobby of creating new animals for the Zoo Tycoon 2 game. The last time was when he posted on fossil pronghorns while I was creating some for the game and the second is now. And besides we can all use a laugh.

    I created a bare-throated tiger heron (Tigrisoma mexicanum)and when testing it one of the virtual birds decided to sunbathe and I think the AI got a little confused…

    Link to this

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