Bird measurement

Bird measurement or bird biometrics are approaches to quantify the size of birds in scientific studies. The variation in dimensions and weights across birds is one of the fundamental sources of diversity among birds, and even Within species, dimensions may vary across populations within species, between the sexes and depending on age and condition. In order for measurements to be useful, they need to be well defined so that measurements taken are consistent and comparable with those taken by others or at other points of time. Measurements can be useful to identify species, quantify functional and ecomorphological differences, study growth, variation between geographically separated forms, identify differences between the sexes, age or otherwise characterize individuals birds. While certain measurements are regularly taken in the field to study living birds some others are applicable only to specimens in bird collections or measurable only in the laboratory. The conventions used for measurement can vary between authors and works, making comparisons of sizes a matter that needs considerable care.