Bird Eggs - Colours and Patterns (1 Viewer)

Just been looking at some photo's of Guillemot eggs, and it suddenly struck me that I have no idea how the colours, spots, streaks, curlicues, splodges, spatters etc etc on bird eggs are formed/created.

Can someone enlighten me please ??

If they are from a Guillemot colony could guess what the 'splatters' are, otherwise can't help...

Paul Higson said:

Just been looking at some photo's of Guillemot eggs, and it suddenly struck me that I have no idea how the colours, spots, streaks, curlicues, splodges, spatters etc etc on bird eggs are formed/created. Can someone enlighten me please ??

Click to expand...

Paul,
Here's a reference; http://museumvictoria.com.au/about/mv-blog/mar-2012/the-colour-of-bird-eggs/.

However, it doesn't go into the physical biology that produces the patterns.
MJB

Unsurprisingly, the coloration is concentrated on the outer surface of the egg (the cuticle). The pigments are secreted by specialized structures in the oviduct. Typical colors (reds, browns, blues) derive from blood and/or bile. (White is the natural color of shell.)

What I don't know is how the spatial pattern of spots is determined. If you've made easter eggs, you know it's easy to get solid colors: just let the whole egg swim in pigment. But you need some mechanism of control if you're going for a pattern of spots. One possibility might be that the spot pigment doesn't travel. Then if the egg holds still in the oviduct, a pattern can be printed by a corresponding pattern of pigment cells inside the oviduct.

Another possibility is that the pattern is determined by the protein matrix of the cuticle (perhaps based on a pattern in the pore proteins in the calcium layer). The pigment that's destined to make spots washes over the egg but only sticks in predetermined places.

In either case you still have to create a spatial pattern - but that's standard evo-devo stuff