Egg tooth!

Last week a friend and I saw a Cape Barren Goose behaving strangely on a clifftop at Phillip Island; it appeared to be alone but was scanning the sky and looking around rather than resting or foraging. We drove slowly and were lucky to notice its mate sitting among the saltbush on a well-hidden nest.

 

Cape Barren Goose (Cereopsis novaehollandiae) – gosling
1/1600, f/8.0, ISO 1600

 

The following morning both adult geese were foraging beside the nest. We watched from a distance and soon saw some tiny heads peeking above the greenery. Cape Barren Geese are large, grazing birds and their little ones were already busily finding their own breakfasts.

What we didn’t notice at the time was the tiny egg tooth on the end of each gosling’s bill.

 

Cape Barren Goose (Cereopsis novaehollandiae) – gosling
1/1600, f/8.0, ISO 1600

 

The egg tooth is a remarkable structure that enables chicks to break out of their eggs. When the embryo is ready to hatch it can no longer absorb oxygen through the shell and uses the egg tooth to break a hole in the air sac at the broad end of the egg. It uses the released oxygen as it begins the hatching process, gradually working its way around the egg, pecking at the shell with the egg tooth. It gets the strength to do this from a pipping muscle at the back of its neck.

The egg tooth in birds, reptiles and monotremes is either reabsorbed or falls off shortly after hatching.

 

Cape Barren Goose (Cereopsis novaehollandiae) – gosling
1/1600, f/8.0, ISO 1600

 

The geese foraged towards us, which is always a great sign as it means the birds I am photographing are not bothered by me or my camera. I rarely shoot with other bird photographers but I occasionally see people walking towards birds to try to get a shot. From what I’ve seen they tend to spook the birds and probably add to their collection of birdbot images. I much prefer to wait at a distance and hope the birds will forage towards me. Sometimes they do and sometimes they don’t, which means I might miss out on shots altogether or I might be lucky enough to capture some beauties of birds behaving naturally.

The image above shows the egg tooth quite clearly, along with a sense of scale showing how tiny the goslings were.

 

 

Cape Barren Goose (Cereopsis novaehollandiae) – gosling
1/1600, f/8.0, ISO 1600

 

I could hardly believe my luck when this little one appeared in mini-clearing amid the saltbush.

A few decades ago this species was almost extinct; they are still one of the world’s rarest geese species. I feel extraordinarily grateful to all the dedicated scientists and volunteers who have worked so hard to keep Cape Barren Geese on the planet.

Happy birding

Kim

 

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