I wanted to do a similar study of wing loading with the urban birds of Lima, I have data of ~1500 individuals in 10 years. I got involved in other issues and never published this. Checking my original file of 2003, I had this papers as references for my project:

Johnson, D. 1997. Wing loading in 15 Species of North American Owls. In General Technical Report NC-190 of the 2nd International Symposium: Biology and Conservation of Owls of the Northern Hemisphere, Winnipeg, Canada.

Nordmeyer, A., Oelke, H. & Plagemann, E. 1970. Biometrical studies on House Sparrow, Passer domesticus (L.), populations in Northwestern Germany. In Proceedings of General Meeting of the working group on granivorous birds, IBP, PT Section. The Hague, Holland.

Shaffer, S.A., Weimerskirch, H. & Costa, D. P. 2001. Functional significance of sexual dimorphism in Wandering Albatrosses, Diomedea exulans. Functional Ecology 15, 203-210.

Hope this helps you

Handbook of Field Methods for Monitoring Landbirds

edited by C. John Ralph

http://www.tandfonline.com/doi/abs/10.1080/00063659809461082#.Uzqjl_l_uQk

Something like this?

I wanted to do a similar study of wing loading with the urban birds of Lima, I have data of ~1500 individuals in 10 years. I got involved in other issues and never published this. Checking my original file of 2003, I had this papers as references for my project:

Johnson, D. 1997. Wing loading in 15 Species of North American Owls. In General Technical Report NC-190 of the 2nd International Symposium: Biology and Conservation of Owls of the Northern Hemisphere, Winnipeg, Canada.

Nordmeyer, A., Oelke, H. & Plagemann, E. 1970. Biometrical studies on House Sparrow, Passer domesticus (L.), populations in Northwestern Germany. In Proceedings of General Meeting of the working group on granivorous birds, IBP, PT Section. The Hague, Holland.

Shaffer, S.A., Weimerskirch, H. & Costa, D. P. 2001. Functional significance of sexual dimorphism in Wandering Albatrosses, Diomedea exulans. Functional Ecology 15, 203-210.

Hope this helps you

Thanks everyone for all the helpful answers! I guess these are good for a start.

Hi

First, just to add to the relevant references list, I recommend looking on Pennycuick’s work. He dealt with wing load quite a lot. Specifically look on his book (Modelling the flying bird 2008, I think you can even find the PDF online). He also has “Flight” a free software you might find useful for analyzing the data you collect on wing load in the context of flight speed etc (http://www.bristol.ac.uk/biology/people/colin-j-pennycuick/index.html )

Second, as a practical advice, I agree with Luis Carrascal’s advice, and can further simplify it. We did a similar thing in two different projects, working on bats and vultures. The easiest way we found is to simply take the picture of the wing, starched on a flat area with a strong contrast (a white page on a table will do). Try to consistently, take the pictures from the same distance and as perpendicular as possible (see attached picutr). Make sure you include something in the picture for scaling (e.g. a ruler). Later you can use imageJ (http://imagej.nih.gov/ij/) to analyze the wing area (you will have to go manually picture by picture and cut off the fingers from the calculated shape). Here is the bat reference for example:

Grodzinski et al 2009 Context-dependent flight speed: evidence for energetically optimal flight speed in the bat Pipistrellus kuhlii? J Anim Ecol

Good luck.

Orr

When we were doing morphometrics on Northern Goshawks we utilized a plexiglass frame gridded with 10mm squares, that we placed the wing over and then photographed. This worked very well to determine surface areas. We used mass of the individual minus crop if any. In prey density dependent species such as Goshawks the mass, especially in breeding males may vary considerably from year to year while surface area remains steady as the population goes through a prey population cycle.

Here at Western University in London, Canada, we have the Advanced Facility for Avian Research (AFAR). Prime among the research facilities at AFAR is the world’s first hypobaric climatic wind tunnel for bird flight. Researchers can study the physiology and aerodynamics of bird flight in relation to varying conditions of altitude (air pressure can be adjusted to mimic altitudes of up to 7000 m), temperature, and humidity. So, in addition to the great suggestions above for the calculation of wing loading values across individuals, species, and seasons, AFAR's hypobaric climatic wind tunnel for bird flight would allow for the examination of functional performance of birds with similar/different wing loading values under all sorts of conditions like they would experience in nature (e.g., during migration). Check out their website at:

http://birds.uwo.ca/AFAR/Welcome.html

I am also attaching a pdf of a brief overview of AFAR that was published in Science in 2011.

You might also look at: Scott, S. D., and C. McFarland. 2010. Bird feathers: a guide to North American species. Stackpole, Mechanicsburg, Pennsylvania, USA. for how they placed birds with various wing loads into groups. I used their groups in a paper recently: Sporer, M.K., J.F. Dwyer, B.D. Gerber, R.E. Harness, and A.K. Pandey. 2013. Marking power lines to reduce avian collisions near the Audubon National Wildlife Refuge, North Dakota. Wildlife Society Bulletin: 37:796-804.

I appreciate the given hints, thank you!

Hi!

We are doing basically the same thing as Orr with birds, and the protocol works quite well, as far as I know. You can take the picture from almost every height if you have a ruler near the wing and the photo is taken perpendicularly as possible. You can always re-caliber your ruler in imageJ. After that, you split the area with the body mass.

Trace wing shapes from images using Sigmascan pro software; wise to include the body areas. Express mass (measured from the field) in Newtons and the area (calculated from sigma scan) in square meters. For intricate details, check the following sources: Norberg and Rayner 1987. Ecological Morphology and Flight in Bats; Lockwood et al. 1998 Avian wing tip reconsidered; Jacobs et al. 2007. The allometry of echolocation call frequencies of insectivorous bats. These papers give easy to follow methods and a broad overview how to analyse and interpret the data.

All the best!

Hi,

The main thing you need to decide is if you want to measure the area between the two wings or not. There is a lot of variability in the literature about this. Very often, researchers interested by flight capability at takeoff do not report the area between the wings whereas those interested at modelling and estimating flight costs do.

Another important point is to standardize the streching method of the wings. We determined that measurements errors account for 42 % of the total variability. You can check our method in Guillemette & Ouellet (2005) "Temporary flightlessness in pre-laying common eiders Somateria mollissima: are females constrained by excessive wing-loading or by minimal flight muscle ratio". Ibis 147;293-300.

Well this be true. The question was about wing loading. To be truthful most researchers ignore the tails which can and do serve as a "third wing" in certain species such as soaring buteos. Having studied raptor migration for over thirty-five years it is quite apparent that soaring birds utilizing thermals for lift are also using their rectrices.

Thanks for the additional answers for each of You! Reading the suggested literature I decided to also measure the wingspan in order to calculate the "wing root box" (according to Pennyquick's terminology) -- this seems to be more accurate determination of the wing area than that of without it. However, I'm somewhat hesitant with the tail as studies are usually ignorant of this, the „Modelling the Flying Bird” book also puts it aside and most of all because the standardization of it (e.g. spreading the tail feathers) seems to be quite a problem. My study question does not involve anything of migration, modelling, or flight speed or distance, etc., so I’m not sure how much do I need this measure to calculate the wing loading properly.

Come to the Burke Museum and measure wing area directly using the extended wing collection. All are fully extended, so well standardized for such measurements and we have a planimeter that makes the measurement easy. Plus, the specimens have weights, so you don't need to use means from the literature. This is the largest extended wing collection in the world, and UPS in Tacoma, which is close by, also has a large collection. I recently measured loadings for more that 200 species from all over the world this way.

We usually transform the body mass into the body mass index for

which the body mass is divided by the third power of the wing-length. It serves as an excellent indicator of wing loading in birds.

E.g.: Krams, I., Cirule, D., Suraka, V., Krama, T., Rantala, M.J., Ramey, G. 2010. Fattening strategies of wintering great tits support the optimal body mass hypothesis under conditions of extremely low ambient temperature. Functional Ecology 24: 172-177. DOI:10.1111/j.1365-2435.2009.01628.x

Make a tracing of the fully extended wing, you can then measure its area with a planimeter, or make a cutout and measure it on a leaf area meter or with a program like Sigma-scan (there are also several programs free online) with a standard measure (say 2x2 cm or 4 cm2, or 2x5 for 10 cm2) for comparison. Wing loading is the body mass divided by twice the wing area.

FGStiles

I mostly agree with Gregory Mutumi, but I would say it is NOT ONLY wise to include the body areas, I would say you DEFINITELY SHOULD include the body areas (like wing area on this picture:https://dfzljdn9uc3pi.cloudfront.net/2014/234/1/fig-11-2x.jpg)

There is one and only one way to measure wing area for use in aerodynamic calculations that can be replicated. It is described in detail by CJ Pennycuick in his ebook Modelling the Flying Bird 2008 (pg 12, Box 1.4). The real question is why are you measuring wing loading? It is a concept applicable to fixed-wing aircraft and is not part of the theoretical constructs for flapping flight. You do, however, need CJP's "wing area" to calculate aspect ratio, a parameter affecting glide efficiency.

Another question besides how to measure wing loading is why or how you plan to use it? Using museum specimens provides a single measurement for one population. In birds measurements often vary between populations or subspecies of a single species. For example the Loggerhead Shrike breeding in Wisconsin has a longer wing chord than tail length. The Loggerhead Shrike in southern USA has just the opposite. One migrates and one doesn't. Similar patterns can be found in many species and in particular raptors. It has also been suggested that wing loading may vary between juveniles and adults. I would deal with measurements from your study population to be accurate.

Wing loading is important as a determinant of speed at take-off, e.g. to escape an attacking predator. You might be interested to read the following paper: Krams, I. 2002. Mass-dependent take-off ability in wintering great tits (Parus major): comparison of top-ranked adult males and subordinate juvenile females. Behavioral Ecology and Sociobiology 51: 345-349. DOI: 10.1007/s00265-002-0452-8

Good point Indrikis. WL at takeoff led paleontologists to propose running in early birds even though they lacked the skeletal architecture for flapping musculature. WL is not a parameter used in estimates of energy requirements for flight - heavy birds just fly faster and fast birds can carry any weight that is adaptive Ie.g. huge eggs).