Over the last century, the beak size of the birds studied has increased from around 4 % to 10 %.
Australian researchers have studied 86 bird species held in several museums to measure how their bodies have changed over the last century in response to global warming. The data provided by the scanners enabled the researchers to demonstrate that the beak size of the birds studied increased from around 4 % to 10 %.
One of the most astonishing effects of global warming has been occurring for several decades: many bird species around the world are reacting to rising temperatures by "metamorphosing" - modifying their beaks, legs and other appendages - in a desperate effort to adapt and survive.
A closer look at how nature has equipped birds to perform this impressive feat of thermoregulation reveals that the beak is one of the most efficient parts of a bird's body thermostat. This living, highly vascularized organ, rich in a ramified network of blood vessels, can draw more blood to its beak at night, dispersing excess body heat and lowering its temperature to a level more conducive to sleep.
The secrets of avian metamorphosis revealed by 3D technology
The study, carried out by doctoral student Sara Ryding of Deakin University, Melbourne, highlights almost 6,000 birds representing 86 different species, spread across 10 bird orders.
In order to achieve the highest level of accuracy, the university contacted Artec 3D's local partner Objective3D and chose the Artec Space Spider scanner, a portable, metrology-grade 3D scanner widely used by researchers and other professionals around the world, with stringent requirements for accuracy and resolution.
The traditional method of detecting bird metamorphosis requires the use of digital calipers to calculate the length, width and depth of a bird's beak. These dimensions are then integrated into an equation that gives researchers the surface area of a cone the same size as the beak.
"I'm interested in a wide variety of birds, from ducks to passerines to birds of prey... When you study such diverse species, you're bound to come across a wide variety of beak shapes. That's why I think 3D scanning is so well suited to this kind of application, because it allows you to digitize the entire anatomy of an organic surface, without leaving anything out."comments Sara Ryding.
During her scanning days, the researcher visits various museums with one or more specific species in mind. She finds these species and starts looking for those to be scanned, depending on the year the specimen was collected, where it was found, and so on.
When the birds are small, she can scan 40 to 50 in an afternoon. For larger birds, 30 to 40 is a more realistic target.
Reliable 3D data eclipse manual measurements
The scanning method is simple: the bird is positioned on its back on a turntable. Then, by slowly rotating the turntable, it is scanned, digitizing all the essential anatomy of the beak in a single scan. Around two minutes are needed to obtain an ultra-precise scan, with a myriad of possibilities.
" Space Spider digitizes every curve and dip in the beak's anatomy, enabling the surface area of the beak to be determined with millimeter precision. "says Sara.
So far, the study has shown that over the last century alone, the beak size of the birds studied has increased from around 4 % to 10 %.
Sara Ryding processes the scans in Artec Studio software. She needs just 6 minutes per bird. " My method of processing scans is as follows: I perform a global registration, then a removal of outliers, followed by a clean merge, which retains everything, even the tiniest details, in sharp focus. Then I apply the texture to make sure I can see where the feathers end and the beak begins. Then I eliminate the superfluous, so that only the beak remains in the scan. "describes the researcher.
Sara Ryding then uses the Artec Studio measuring tool to quickly obtain linear measurements of the spout, to verify the dimensions measured with the digital calipers, and then performs an area measurement, which measures the entire area of the spout.
The essential need for 3D scanning for biological research
According to the doctoral student, 3D scanning is essential to achieve this goal reliably: " If we are to facilitate our studies, from one researcher to another, it is imperative that we have precise, directly comparable data. Manual measurements are no longer enough."
For researchers without access to high-performance 3D scanners, Sara Ryding and her team are improving on the existing formula (using geometry) for estimating bird beak size, by comparing formula estimates with precise measurements of 3D models created with the scanner.
Sara Ryding's study is still ongoing, and involves the addition of further formulas and the examination of a wider variety of species.