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Pink-necked Green-pigeon: egg tooth

on 19th January 2018

PBGP-ch-egg tooth [Trustmind Ng]

Trustmind Ng’s image of a Pink-necked Green-pigeon (Treron vernans) chick above shows an egg tooth at the tip of its bill. On the other hand, Linee Yeo’s image below shows the egg tooth had recently dropped or reabsorbed, thus the blackish tip of the bill.

PNGP xch-fallen [LineeYeo]

Now, what is an egg tooth? In preparing for hatching, the bird embryo develops an egg tooth. This is a short pointed, calcareous structure on the tip of the upper beak (sometimes also on the lower beak as well LINK. It disappears soon after hatching, either reabsorbed or simply dropped off LINK.

According to Winkler (2004), the bird’s embryo is generally in a typical “foetal position” inside the egg with its head bent forward towards the belly. Towards the end of incubation, the fully developed embryo straightens upward. Its egg tooth would then touches the inner wall of the shell around the blunt end of the egg. By this time the egg shell would have been weakened as a result of the absorption of calcium by the developing embryo. And as the embryo turns inside the egg, the rubbing continues until eventually a small hole appears in the egg shell. The egg is then said to be pipped. A few more holes follow until the weakened shell breaks open and the chick struggles free.

Trustmind Ng & Linee Yeo
Singapore
12th January 2018

Reference:
Winkler, D.W., 2004. Nests, eggs, and young: Breeding biology of birds. In: Podulka, S., R. W. Jr. Rohrbaugh & R. Bonney (eds.), Handbook of bird biology. Cornell Lab of Ornithology, Ithaca, New York. Pp 8.1-152.

This post is a cooperative effort between Birds, Insects N Creatures Of Asia and BESG to bring the study of birds and their behavior through photography and videography to a wider audience.

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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