Oriental Darter (Anhinga melanogaster) Feeding Technique

posted in: bird, Feeding | 0

The Oriental Darter (Anhinga melanogaster) population in Perak, Malaysia has progressively grown in recent years, with an increasing number of birds seen at some wetland sites. In the past (2009-2018), one to two birds were observed each year, but since 2019 we have been seeing growing numbers and, in the past year, 10-20 birds in a group. This has enabled more detailed observation for this species.   

On 8th December 2022 I saw 4 birds at a wetland cum fish farming site; two birds were actively feeding. They would plunge underwater and after sometime emerge, often with a fish. The fish is speared underwater. Once emerged, the fish is tossed in the air and caught, head first, in the beak, before being swallowed. The prey is often alive when swallowed (fish seen wriggling), although there is an attempt to shake the head and bill a number of times to stun it. The tricky bit is the air toss, as I saw prey lost once.   

The composite image below shows the process once the bird has emerged. What is missing, in the sequence, is the air toss of the bird to reposition it. 

Some additional observations: 

  • The body remains submerged when feeding, with only the head and neck above the water. 
  • The birds forage individually with no cooperation. 
  • The bird may emerge many meters away from the original point of submersion. 
  • I measured durations of submersion from 1 minute 45 seconds to 3 minutes 30 seconds. 
  • The fish taken appear to be some species of Tilapia. 

  

Dato’ Dr Amar-Singh HSS 

Ipoh, Perak, Malaysia 

8 December 2022

 

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