"Early morning aerobics" Swift tern after a dive

Swift Tern : Woodbridge Island Copyright Vernon Chalmers)

Why do (swift) terns fly upside-down?

This a question that was asked on the images I posted of the 'terning'' terns in the Birdlife South Africa Facebook Group

After a dive for fish they shake off the excess water.

In this series of five consecutive images a swift tern just emerged from the water and twist it's head / tail for a very rapid shake off

Description: Swift tern shaking off water after an unsuccessful fishing dive attempt into the Diep river, Woodbridge Island Cape Town.

The swift tern is also known as the greater crested tern (Thalasseus bergii)

Images below are 5 consecutive frames with the quick-shooting Canon EOS 7D Mark II.

This is a regular occurrence during most of our summer months. The sandwich tern follow similar behaviour in an attempt to get rid of the water.

Cape Town Location
Diep River - Woodbridge Island, Cape Town

Equipment Used (Birds In Flight / Action Photography)

• Canon EOS 7D Mark II DSLR camera body
• Canon EF 400mm f/5.6L USM Lens
• Lexar Professional 800x / 120MB/s 32GB CF Card

Manual Mode Settings

• Shutter speed: 1/4000s
• Aperture: f/5.6
• Focal length 400mm
• Auto-ISO (ISO 640)
• Continuous shooting mode (10 fps) / AI Servo
• AI Servo / AF Mode Option (Wide Zone AF / Case 1)
• Lens AF On / No IS / Handheld

(Click to enlarge)

Swift tern in flight : Woodbridge Island, Cape Town   Frame 1 / 5

Swift tern in flight : Woodbridge Island, Cape Town   Frame 2 / 5

Swift tern in flight : Woodbridge Island, Cape Town   Frame 3 / 5

Swift tern in flight : Woodbridge Island, Cape Town   Frame 4 / 5

Swift tern in flight : Woodbridge Island, Cape Town   Frame 3 / 5

Canon EOS 7D Mark II - Birds in Flight Photo Gallery

Canon EOS 7D Mark II - Birds in Flight Photo Gallery

Woodbridge Island Cape Town Bird Species

Woodbridge Island Cape Town Bird Species