Dramatic photo captures moment giant bird closes hidden 3rd eyelid while snatching locust from mid-air

A secretary bird catching a locus with its beak.

A bizarre photograph captures the moment a secretary bird (Sagittarius serpentarius) closes its third eyelid as it catches a locust midflight. The image is one of the winners of the 2024 Royal Society Publishing Photography Competition, which is run in collaboration with the Royal Photographic Society, and recognizes images showing hidden scientific phenomena in the natural world.

The secretary bird was captured by biologist and photographer Peter Hudson, who was named winner of the ecology and environmental science category.

"Secretary birds are closely related to falcons but have evolved a stork-like mode of life, where they stalk around the savannah and feed on locusts, lizards and amphibians by punching them on the ground," Hudson said in a statement emailed to Live Science. "This bird has just caught a locust, and as it swallows its prey, it synchronously closes its third eyelid, the nictitating membrane, across its eyes to protect them from damage."

Related: Shoebill: The human-sized African bird that eats baby crocodiles and kills its siblings

Secretary birds are large birds of prey — reaching around 4 feet (1.2 meters) in height — with an eagle-like body that sits on long, crane-like legs. They're native to sub-Saharan Africa and, while they can fly, they spend most of their time walking through long grasses looking for food.

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Hudson's image reveals the bird's third eyelid, which looks like a blue ball sitting in the eye socket. According to the National Audubon Society, the third eyelid sits beneath the upper and lower lids. It's hinged at the inner side of the eye and moves horizontally across the eyeball to keep it free of dust, wind and hazards — giving the eyelids the nickname "nature's goggles."

An aerial image of four sharks hunting in a school of fish was named overall winner of the competition. It was taken by Angela Albi, a researcher at the Max Planck Institute of Animal Behavior in Germany who studies interactions between sharks and fish.

Albi's image of sharks hunting was named overall winner. (Image credit: The hunt from above by Dr Angela Albi (Drone pilot: August Paula))

"Just after sunrise or before sundown, the shallow waters of the Maldives become a clear, see-through surface," she said in the statement. "These are also the moments when we best observe the interactions between reef sharks and their prey. In this frame, captured during a research trip in 2024, a shark on the far left shifts suddenly from swimming calmly within the school to initiating a hunt, its body posture standing out from the others. While we still don't know what triggers these attacks, we analyze videos to study how sharks hunt and how their prey responds collectively."

The winners from the astronomy, earth science and microimaging categories can be seen below.

Secretary bird gullet by Peter Hudson. (Image credit: Secretary bird gullet by Peter Hudson)

Heart and Soul by Imran Sultan. "Found over 7000 light years away, the Heart and Soul are two breathtaking nebulae in the Cassiopeia constellation. The nebulae are immense regions of star formation in our galaxy — my picture shows an area of the sky that is nine full Moons across. To capture their intricate details, I photographed the faint nebulae for nearly 14 hours over three nights in fall 2023, from the city skies of the Chicago suburbs. Ionized gas in the Heart and Soul glows in vivid colors, shown here in the HOO color palette, where hydrogen is mapped in red and oxygen appears as blues and greens. I was able to overcome the extreme light pollution of city skies, a growing challenge that is detrimental to both stargazing and astrophotography, by using a special filter which only allows certain wavelengths of light to pass through." (Image credit: Heart and Soul by Imran Sultan)

Ice cap melt lake in Greenland by David Garcia. "The photo depicts a supraglacial melting lake over the Greenlandic ice sheet, ranging from some meters to several kilometres wide. Increasing in numbers due to climate change, they can suddenly drain if a crack in the ice appears, hydrofracturing, collecting water at the bottom of the lubricating the glacier and speeding its flow towards the ocean. Greenland's ice sheet is the second largest ice mass in our planet, and its melting would raise the sea level approximately 7 meters. Taken during a flight from Kangerlussuaq to Ilulissat, when a small window of light appeared, it was singular due to hundreds of small aquamarine structures formed by melting and thawing process. Although some clouds cast shadows over the lake, I was elated to have captured the image." (Image credit: Ice cap melt lake in Greenland by David Garcia)

Tired eyes by Jose Manuel Martinez Lopez. "This image depicts the eyes of a bark scorpion (Centruroides exilicauda) from Baja California, Mexico, observed under fluorescence using a 10x/0.3 objective lens. The appearance of the scorpion's eyes in the photo is not typical; after several hours of working with the specimen, the scorpion dried out, allowing me to capture the 110 images necessary for the focus stacking process." (Image credit: Tired eyes by Jose Manuel Martinez Lopez)