Wing loading information (1 Viewer)

Does anyone know of a good source for wing-loading data on all of the bird species commonly seen in North America?

I've come to understand how much wing-loading figures can suggest about flight styles and speed. I'd love to be able to go to a single list, webpage, or book to look up reliable figures for newly seen birds, so as to make it part of a internal mental 'database' of different species' characteristics.

https://sora.unm.edu/sites/default/files/journals/auk/v055n03/p0511-p0517.pdf

Not something that I have ever looked at. Some surprising numbers.

As often happens, posting a question made me look into it again myself, and I've just found:

Earl L. Poole, “Weights and Wing Areas in North American Birds,” Auk 55:3 (July 1938): 511–517,

which has figures for 143 species and was pretty much what I had in mind, except for being 80 years old; and

Thomas Alerstam, Mikael Rosén, Johan Bäckman, Per G. P Ericson, and Olof Hellgren, “Flight Speeds among Bird Species: Allometric and Phylogenetic Effects,” PLoS Biology 5:8 (August 2007): e197,

which throws cold water on the idea that wing loading can be translated directly to flight speed.

Yes! The Earl L. Poole article is in jmepler's direct link to the University of Minnesota site for ornithological P.D.F.s.

Hi Peter,

Peter Audrain said:

Thomas Alerstam, Mikael Rosén, Johan Bäckman, Per G. P Ericson, and Olof Hellgren, “Flight Speeds among Bird Species: Allometric and Phylogenetic Effects,” PLoS Biology 5:8 (August 2007): e197,

which throws cold water on the idea that wing loading can be translated directly to flight speed.

Click to expand...

I wonder, did they provide a reason for the lack of a direct relation?

I'd imagine active (flapping) flight might give birds opportunities to operate at quite varied speeds depending on their other physical parameters. Quite intriguing to think about differences in gliding flight ...

With regard to American birds, I believe the Wright brothers were quite interested in their flight-relevant parameters too, and from their book "How we invented the Airplane", it seems they often watched gliding birds and tried to establish their approximate glide ratio

Regards,

Henning

Hauksen said:

I wonder, did they provide a reason for the lack of a direct relation?

Click to expand...

The gist seems to be that airspeeds vary a lot less than wing loading varies—the range of airspeeds is 'compressed'—because other things affect the speed of birds' flight, too. One such thing is their wings' aspect ratio: as wing load increases, wings tend to become deeper, from leading to trailing edge, and wingspan tends to decrease.

Obviously another factor is the cadence at which birds flap. Loons and sea ducks with high wing loading (and high aspect ratios) flap quickly and don't attempt to soar. Partly, as an aerodynamic matter, they have to if they hope to stay airborne; and partly they may just want to move faster.

Different families have different wing designs, and the specific details of those designs—in other words, what they're evolutionarily best adapted for, whether it's soaring, navigating through brush, or quartering, for instance—has a lot to say about the speeds they usually achieve.

As the authors sum it up, in language that is only slightly too elevated, "functional flight adaptations and constraints associated with different evolutionary lineages have an important influence on cruising flapping flight speed that goes beyond the general aerodynamic scaling effects of mass and wing loading." This is commonsensical enough that I wonder a little whether they framed their article to refute a straw man.

As an unscientific observer, I am interested not so much in airspeeds as in the way birds look when flying, and what sorts of flight they are most comfortable with. Wing loading is only one number among many, but it does explain some of this variation, and I think helps me to understand flight styles.

For instance: the online edition of Birds of North America notes that male Northern Harriers "have shorter wings and lower wing-loading than females … and appear more agile in flight." Partly because of lower wing loading, males burn only about 4.7 Watts in flight compared to females' 5.6 Watts, and have been observed outclimbing Prairie Falcons.

Male Short-eared Owls, which have a wing-loading factor of 0.281 g/cm^2 (females' wing loading is 0.385 g/cm^2; David H. Johnson, "Wing Loading in 15 Species of North American Owls," paper presented at Biology and Conservation of Owls of the Northern Hemisphere symposium, February 5–9, 1997), have famously 'buoyant' flight, and are able to outclimb pretty much any bird they meet.

So there's more to life to airspeed, even if wing loading can't be treated as a universal explanation for the ways birds fly.

P.S. Given what you say, I'm all but guaranteed to go down a Wright Brothers rabbit hole next! Thanks for mentioning their book.

Great topic. I can’t contribute anything other than I have built a lot of model airplanes and I was always instrested in slow flight and this seemed to always require lots of wing area and light weight. Vultures always seemed to be good models to copy. The Mourning dove is a fast flyer and appears bulky. I have watched them attempt to land on my feeder and they have trouble flying slow enough to land. As I said, nothing to contribute, but it is an interesting topic.

That's fascinating, about trying to achieve slow flight. I have the impression that a fair number of fast-flapping seabirds also make pretty hard landings, like your doves! Plowing messily into the water. High wing loading and the overall difficulty of slowing down might be part of the reason.

This is not really related—except insofar as windspeed visibly affects what birds will try to do, especially in terms of soaring (even Robins can soar in the right wind)—but we had high winds here today, and I saw a Bluebird casually fly, with no visible effort, deviation, or concern, from a tree back to its house, right in the thick of the gusts. It was as if the winds, which could make you shriek with cold, weren't even blowing. Birds are really good at what they do.

I do wish there were more 'numbers' (like wing loading) included in standard field guide entries, and more information about flight style that went beyond broad-brush impressions.