While wondering when we were likely to be able enjoy group Sunday Outings again I thought about where in the past we had been sending the information about these Outings…birds seen and their numbers etc. I checked with Marianne, who confirmed that our sightings were sent to eBird Australia.

These are then sent to the Cornell Laboratory of Ornithology in the Ithaca region of the USA, where sightings from all over the world are kept and collated.
 
I then thought about several visits Malcolm and I had made there in 2019, the first on 2nd of July, and the second on 23rd of December, (when it had been snowing, the central lake frozen, and the only birds seen were at a bird feeder) See photograph #1.
 
In July we enjoyed a “behind the scenes” tour in the large building, given by a volunteer guide, who after a short talk on the history of the complex took us into various laboratories to see many specimens and also hear sound recordings. She also pointed out a huge mural which had been painted on a tall inside wall. It was covered with paintings of a member of each bird family in the world superimposed on the continents. See photograph #3.
 
After this the group went their separate ways. We walked around one of the paths in the adjoining Sapsucker Woods Sanctuary which surrounds this Centre for Birds and Biodiversity. We took the Wilson Trail, which incidentally has bird call recorders at various stations along it, and walked in a clockwise direction around the central pond, which was covered with waterlilies.
 
The sanctuary is named after the Yellow-bellied Sapsucker, a furtive mainly silent Woodpecker which gets its name from the habit of boring holes into the inner bark of a tree. They then suck up the oozing sap with their brush-like tongues. They are mainly silent, so it was no surprise that the only ones we saw were a pair of taxidermed ones in a glass case in the foyer of the main building! A Downy Woodpecker was the only one we saw, and it’s the smallest and most commonly seen. See photographs #4 and 5.
 
Returning to the centre we sat in comfortable chairs looking through telescopes, a number of which were set up by the windows overlooking the ponds. If ever we visit the family in Ithaca again we will be back there!

Apologies for the length of this piece … it become much more technical than anticipated, but I hope you will all find it interesting.
 
Structural Colouration
 
Margie Tiller mentioned recently that Joan Paton told club members many years ago that the blue colour of birds is not from actual pigments.  I thought I’d investigate a little further. 
Blue and iridescent colours in birds are never produced by pigments. They are "structural colours”.  English scientists Robert Hooke and Isaac Newton first observed (from a scientific viewpoint) this phenomenon in living creatures.  
 
In Hooke’s 1665 book, Micrographia, he said of the peacock,
 
“… each Feather in the tail sends out multitudes of Lateral branches, … so each of those threads in the Microscope appears a large long body, consisting of a multitude of bright reflecting parts.
 
… their upper sides seem to me to consist of a multitude of thin plated bodies, which are exceeding thin, and lie very close together, and thereby, like mother of Pearl shells, do not only reflect a very brisk light, but tinge that light in a most curious manner; and by means of various positions, in respect of the light, they reflect back now one colour, and then another, and those most vividly.”
 
A century later, Thomas Young (1773 – 1829) explained the principles behind structural colouration.  Young was a British polymath who made notable contributions to the fields of vision and light, amongst other scientific discoveries.
 
Structural coloration is the production of colour by microscopically structured surfaces fine enough to interfere with visible light. Peacock tail feathers are pigmented brown, but their microscopic structure makes them also reflect blue, turquoise, and green light, and they are often iridescent. It made me wonder about the real pigment colours of other birds we see as iridescent blue, green, purple etc. Iridescence occurs when the colour changes with the viewing angle and orientation.  Structural colour, however, is no simple matter. In bird feathers, interference is created by a range of photonic mechanisms.  The vivid colouration is caused by interference effects that reflect or scatter light, rather than by pigments. Colours are produced when a material is scored with fine parallel lines, formed of one or more parallel thin layers, or otherwise composed of microstructures on the scale of the colour's wavelength. The detailed structure of the feather’s barbules reflects some wavelengths and absorbs others, and the reflected wavelength changes with the angle of reflection. The structural colour is registered by the eye in response to the reflected wavelengths and changes with the angle formed by the light, the reflecting surface, and the eye.
 
The benefits of structural colouration for birds include for camouflage, avoiding predation, signal communication and sex choice.

I have a few photos taken in Uganda last year to share with AOC members.
 
Photos 1 & 2
Shoebill. (Balaeniceps rex.) Was once allied to the Pelican family but is now classified in its own family. Vulnerable, rare and very threatened it is only found in Africa and reduced to just the swamp areas of Uganda and Rwanda and Zambia. Pairs have a territory about 5 square km. in Papyrus swamps, reeds and sedges. Massive wings and can fly. Claps its bill making a hollow "clock" as a call.
 
Photos 3, 4 & 5
The following three photos show how useful the African Buffalo can be as a safe perch for birds.
 
Photo 3   These are a group of Piapiac, a long legged crow with a heavy decurved bill and a red eye. Common and usually seen in small flocks.
 
Photo 4   Although not very clear in this photo this is the Yellow billed ( Intermediate) Egret. (Ardea intermedia).
 
Photo 5   And a wonderful perch for the Pied Kingfisher.

Musk Ducks   
After visiting Aldinga Scrub CP last week we decided to call in to the Hart Road Wetlands on the way home, to check out the resident male Musk Duck. He was still there, & after watching him for a while I started to ponder on why his tail feathers sometimes appear to be a blue colour when spread out in the water. I was reminded of the time we visited W.A. in September 2019, staying at the Karri Valley Resort, SE of the Margaret River region. The Resort is on a lake fed by water from the Beedelup Falls (and incidentally is a great place to stay). There were a number of Musk Duck there, including the female shown in the photograph, which also was showing blue tail feathers. 
After puzzling about this for a while I eventually remembered one of the WEA lectures given by Joan Paton, (which I attended last century!) when she told us that the blue colour of birds is not from actual pigments. It is created by the way light waves interact with the arrangement of their keratin molecules in the feathers, and which reflect light in subtly different ways to produce different shades of what our eyes perceive as the colour blue. 

 Since all the feathers of Musk Ducks appear to be grey some of the time, and only blue when we see them from certain angles in the water, I assume that refraction of the light rays in the water makes them appear blue to us.
I have not been able to find any published work on the particular subject of whether this is relevant to Musk Ducks, so I might be completely wrong, but it’s the best I can think of! 
 
 (Googling directed me to a relevant article by Scott Sillett, a wildlife biologist at the Smithsonian Migratory Bird Centre, entitled Colour of Feathers in Birds.)