I had extended foraging observation of 11 Chinese Pond Herons for 1.5 hours. This offered an opportunity to see their food items. In addition there was a single Cattle Egret (Bubulcus ibis coromundus) that was feeding with them in the same location and manner.
In the past I have seen them waiting at the edge of ponds to catch fish successfully. I have also seen them ‘hover’ over a pond and ‘dive’ in to catch fish, especially when there is a bird feeding frenzy in the location, due to abundance of fish rising to the surface. More commonly they are found in large drains, at edge of shallow streams, and open grass areas looking for prey. When on grass they adopt a ‘slow-walking’ exploration, as on this occasion - much of the feeding was done by walking, waiting and watching in the tall grass for prey. There was no digging into the earth or probing for items.
Wells 1999 states that the diet of the Chinese Pond Heron is “hardly known”. for my region. HBW 2019 describes prey as “Small frogs, worms, aquatic invertebrates, fish, molluscs, worms, some terrestrial insects and even small birds”. IUCN-SCC Heron Specialist Group states that “much of its normal feeding is unquantified.” Prey includes “flies, aquatic insects, mollusks, worms, fish, frogs, and small birds”. In the past I have seen them take fish in large numbers and a Yellow Striped Tree Skink (Lipinia vittigera) in the grass. On this occasion I saw a number of earthworms and centipedes eaten. On one occasion I saw a leech taken. But I was unable to identify the main item eaten. The birds were initially displaced by my arrival but quickly regrouped at the same location. Although this vacant house has a very large garden, they were all prepared to approach close to my position, as the best feeding was located under an enormous fruiting ficus. Many other birds were feeding in the fruiting ficus in the tree and a reasonable amount of fruit (ripe and unripe) had been dislodged into the tall grass. I began to ask myself if they were also feeding on the fruit? As I watched the feeding (with videos and bust DSLR images) it became apparent that a sizeable amount of their food item was very small, not visible to me. It was picked up from the ground and eaten quickly; the tall grass obscuring the item. Often after swallowing this small food item they would shake the head with an appearance of distaste; very much akin to us having swallowing something sour or bitter. This ‘distaste’ and ‘head-shake’ behaviour did not happen with the worms or centipedes were eaten – they were processed and killed before being consumed offering me time to spot them. I considered a number of possibilities for the food item they were consuming in large volume:
1. Were insects attracted to the fruit on the ground and now being picked off by the Chinese Pond Herons and Cattle Egret?
2. Could the rotting fruit on the ground (under the shade) have developed worms and these were being consumed?
3. They were actually consuming Ficus fruit?
I am not able to find any corroborating evidence of Chinese Pond Herons or Cattle Egrets eating fruit. My personal opinion is possibly worms in the rotting fruit and some fruit is inadvertently consumed accounting for the behaviour I observed. Note that there was some competitive feeding and birds with breeding plumage tended to chase away those in non-breeding plumage. I have edited a short video of feeding behaviour and items here: https://youtu.be/4H8WwhErJeQ
1. Martínez-Vilalta, A., Motis, A. & Kirwan, G.M. (2019). Chinese Pond-heron (Ardeola bacchus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona available here:https://www.hbw.com/species/chinese-pond-heron-ardeola-bacchus
2. The IUCN-SCC Heron Specialist Group. Heron Conservation: Chinese Pond-heron available here: https://www.heronconservation.org/herons-of-the-world/list-of-herons/chinese-pond-heron
3. Wells, D.R. (1999) The birds of the Thai-Malay Peninsula: Vol. 1 (Non-Passarines). Christopher Helm, London