Green LIght, Red Light

Day 17: Remember that game you played as a kid called "Red Light, Green Light?" Hummingbirds like this Anna's have it built in. This remarkable ability to change colour seemingly on a whim is due to the physical structure of the feathers rather than to pigmentation. Microscopic layers within the feather only permit passage of specific wavelengths, and as light strikes the feather from different angles, multiple microlayers combine or cancel specific wavelengths to produce the visual effect of colour change. A hummingbird's shimmering throat feathers may hold as many as fifteen different microlayers, each with a thickness which matches one colour of light. The reflected light we perceive as iridescence is the product of amplification of some colours, reduction of others. With the ability to go from red to green with just a shift of the head, it's no wonder hummingbirds can halt so abruptly mid-air and then be gone in a flash. They've had lots of practice playing "Stop and Go."

Purple When Purchased

Day 335: It was a pretty lavender colour when I bought it. I swear it was. I would not have bought a pink-flowering heather (or a pink-flowering anything else for that matter because I despise pink). It was a nice shade of greyish lavender, the colour one expects heather to be. Maybe it's the pH of my soil, although acidic soils generally influence flowers toward the blue end of the spectrum, as anyone who's ever tried to grow a pink hydrangea in western Washington will know all too well. Maybe it's taking up some of the red dye in the bark mulch I laid around it. That seems a more likely explanation. In any event, when I put in new plants this last spring, I added not one but two pots of heather. The second one isn't quite as rosy, but it's definitely not the same purple it was when I put it in the ground.

Bullfrog Blues

Day 175: As mentioned in an earlier post, the Bullfrogs invading local ponds and creeks can be quite varied in colour, ranging from brown through green, sometimes even aqua blue. The colour of any one frog may change over time as a result of exposure to increasing or decreasing amounts of light, not in response to its surroundings as was once believed. This change is effected in specialized cells and by the manner in which they reflect light. The transition may take weeks or months to occur. The specimen of Rana catesbeiana shown here is entering a blue phase, and if my Bullfrog census for this city park in Yelm is any indicator, the Herons certainly won't be singing the Bullfrog Blues for lack of a hearty dinner.