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Feeding Spotted Dove: 10. More on eyelids

on 28th September 2010

An earlier post dealt with the eyelids of the Spotted Dove (Streptopelia chinensis) where it was mentioned that the upper eyelid can only be lowered half way over the eye. The closing of the eye is thus achieved by moving down the upper eyelid to meet the lower eyelid that moves up to the halfway point (below left).

Subsequent images obtained when the Spotted Doves were indulging in allopreening show that the upper eyelid can and does move lower than the halfway mark, contrary to what the literature says. In this case the lower eyelid does not come into play in the closing of the eye (above right). A point to note is that the upper eyelid is translucent. Thus when the eye is closed as a result of the dropping of the upper eyelid, the bird is still able to see what is going on around.

The image on the left shows that the lower eyelid has moved upwards to completely cover the eye. Note that the fringed edge of the upper eyelid is visible, nearly touching that of the lower eyelid. It is interesting to note that the lower eyelid is made up of two parts – an upper translucent half and a lower opaque half. There is a prominent border between the two halves. As with the upper eyelid, the lower also allows the bird to see when the eyelid is drawn up the eye. The image above-left similarly shows the lower eyelid making up of two parts, except that the lower portion is narrower because it has not been raised to its full potential.

I am not an ornithologist or an avian morphologist. And I have not been successful in seeking out any literature on the eyelids of the Spotted Dove. My interpretation of the morphology of the eyelids is based solely on my images. It would be ideal to be able to examine a specimen, either live or dead, but the opportunity did not arise. As such, I welcome alternative interpretations.

I have also not been able to detect any nictitating membrane in any of my images. Does the nictitating membrane exists in the Spotted Dove? Can anyone provide any information on this?

Check out this post on the eyelids of the Brown-throated Sunbird.

YC Wee
Singapore
September 2010

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.

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