Maltese ornithologist takes a gander at geese as they learn how to fly

Birds are masters of the skies – they fly great distances to find food, shelter, mates, and migrate to escape seasonally adverse weather.

But when they hatch they are unable to do so and rely on their parents for food and protection, gaining flying ability only in the first weeks or months of life.

So how do birds go from grounded, dependent young to confident flyers? That is what Maltese PhD researcher Marie Claire Gatt set out to discover with colleagues from the prestigious Max Planck Institute of Animal Behaviour (MPIAB) in Germany, with whom she recently published the results of their study on young Greylag Geese.

The results are among the first of their kind in the field of ornithology, helping understand the ecology of bird species that depend on extensive flight early in their lifetime.

She joined the MPIAB in the summer of 2015 as a research intern under the supervision of Prof. Dr Martin Wikelski, with the aim of understanding how Greylag Geese expend energy as they start learning to fly.

Using small, cutting-edge data-loggers that were worn by the geese on a ribbon backpack, they measured the birds’ body movements as they flew.

Marie Claire Gatt holds Paula – the most affectionate of the seven geese – in her arms. Photo: K.H Metzger

But to get these devices into the air, they needed willing participants. So Michael Quetting, technical assistant at the MPIAB and aircraft pilot, hatched and hand-raised a group of seven goslings: Gloria, Frieder, Maddin, Nemo, Nils, Paula… and Calimero!

“Michael was the first thing the goslings saw when they emerged from their egg so they considered him their ‘papa goose’ – a process called ‘imprinting’ – and for the next months they would follow him everywhere,” Gatt told MaltaToday – Michael has since published bestselling book Papa Goose about this unique experience.

“I joined this special goose family a few weeks later, and together we trained the geese on land and in the water, and eventually in the air to follow Michael in flight as he flew an electric microlight aircraft.”

Learning to fly: Gatt lets the geese out as they spot ‘Papa’ Michael Quetting on his micro-light and get ready to take to the air

As the data came in, the researchers studied two possible alternatives: the geese were either using less energy as they grew older and became more efficient flyers, with better technique and more energy-conserving behaviours; or they could expend more energy with age as their physical capabilities and flight strength increased and allowed them to.

For the next two months, Quetting and Gatt took the geese on regular short flights around the rural, south-west German landscape near the Max Planck Institute.

The geese improved in their stamina and agility in the air. They flew faster as they grew older, easily keeping up with Quetting’s microlight, and chose to stay in the air for longer.

“At the end of the summer, I was left with a treasure chest of data – 183 individual flights of Greylag Geese aged between two and four months,” Gatt says.

On analysing the data, she found that the geese had increased the amount of energy they put into flight as they grow older. “It therefore appears that in their first weeks of flight young geese are still developing the physical features that make them strong fliers; their wing feathers – each a perfect aerofoil – grow to their full length, and their breast muscles fortify, ready to beat the large wings several times per second. It is probably only once the goose’s body is a purposeful flying machine that the development of more efficient flying behaviour starts to shape the energy they spend in flight.”

Greylag Geese breeding in the north migrate in family groups to warmer areas in autumn, where food is more abundant. So young geese must be physically prepared to fly hundreds of kilometres before they are even a year old.