Folivores – birds that feed on leaves

on 21st November 2011

In December 2005 Cheong Weng Chun shared an image of a juvenile Asian Glossy Starling (Aplonis panayensis) with a bunch of very young rain tree leaflets (Samanea saman) in its bill (above left). And in his own words, the bird was: “chewing – no, can it chew or perhaps, I should say swallow?”

On the afternoon of 16th November 2011, nearly six years later, Weng Chun stumbled upon a flock of approximately 50 Purple-backed Starlings (Sturnus sturninus) among casuarina trees (Casuarina equisetifolia sp.) (above right). And they were pecking on the pine needles (above right).

Sun Chong Hong commented that he had seen “Asian Glossy Starling picked leaflets, both green and yellow ones, of albizia (Paraserianthes falcataria) and then dropped them. I could see the actions quite clearly in these stunted trees in my condo It looked like they were playing with the leaves. It left me wondering what they were up to.” He had also seen sunbirds foraging in casuarina trees and added that “I will not exclude the possibility that they were feeding on arthropods.”

Apparently some birds eat leaves. Known as folivores, these birds may eat leaves exclusively or partially. However, few birds are exclusively folivorous. Why? Because flight demands an enormous amount of energy and leaves do not provide the necessary energy. The energy content of leaves is only half that of fruits and a quarter that of insects and other arthropods. Also, leaf digestion is slow and requires a large storage space in the gut. Besides, digestion needs to be undertaken by specialised bacteria present in the gut.

Those birds that regularly feed on leaves have thus turned to gliding or abandoned flight altogether.

Only about 3% of all birds, from at least 14 families, eat leaves regularly. Most of these birds are terrestrial or aquatic and only 5 families include arboreal members. From these 5 families only 2 species, Hoatzin (Opisthocomus hoazin) and Owl Parrot (Strigops habroptilus) obtain most of their energy from leaves. These include new growth of green leaves, buds, flowers and fruits in season, moss and fungi. Hoatzin is a South American bird whose flight is weak and awkward. It clumsily creeps up branches and makes only short flights. The other is a flightless bird of New Zealand.

Cheong Weng Chun & Sun Chong Hong
November 2011

If you like this post please tap on the Like button at the left bottom of page. Any views and opinions expressed in this article are solely those of the authors/contributors, and are not endorsed by the Lee Kong Chian Natural History Museum (LKCNHM, NUS) or its affiliated institutions. Readers are encouraged to use their discretion before making any decisions or judgements based on the information presented.

YC Wee

Dr Wee played a significant role as a green advocate in Singapore through his extensive involvement in various organizations and committees: as Secretary and Chairman for the Malayan Nature Society (Singapore Branch), and with the Nature Society (Singapore) as founding President (1978-1995). He has also served in the Nature Reserve Board (1987-1989), Nature Reserves Committee (1990-1996), National Council on the Environment/Singapore Environment Council (1992-1996), Work-Group on Nature Conservation (1992) and Inter-Varsity Council on the Environment (1995-1997). He is Patron of the Singapore Gardening Society and was appointed Honorary Museum Associate of the Lee Kong Chian Natural History Museum (LKCNHM) in 2012. In 2005, Dr Wee started the Bird Ecology Study Group. With more than 6,000 entries, the website has become a valuable resource consulted by students, birdwatchers and researchers locally and internationally. The views and opinions expressed in this article are his own, and do not represent those of LKCNHM, the National University of Singapore or its affiliated institutions.

Other posts by YC Wee

5 Responses

  1. Some birds do eat leaves. I assume the sparrows did not defoliate all your plants. It would be interesting to know what plants you have on the roof. Any photographs?

  2. I’ve just witnessed a male cardinal feeding on tomato plant leaf. I have seen the same male cardinal feed leaves from weeds to juvenile.

  3. I live in Edinburgh, Scotland. I have several collared pigeons visiting my garden who pick up the seeds dropped by other smaller birds from my bird feeders but when there are no seeds on the ground they feed on the lilac tree leaves. Prior to having feeders in the garden they really stripped the lilac trees of their foliage but since I’ve had bird feeders they tend to leave the leaves alone but I’ve noticed ripped leaves this year which is a very dry one,

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