After a lengthy day gardening – many, many weeds after recent rains – thoughts were turning to drinks and a shower when a god-awful racket set up in the trees near the garden pond. On investigation this proved to be not the Blue Jays swearing blue murder at neighbourhood cats – the usual cause – but suppertime for the babies.
Three (?4) juveniles were lined up a fir tree branch demanding food and the parents were back and forth providing it. There was zero fear of us creeping around in the undergrowth though there was intense interest being shown in the goings-on by a nearby squirrel.
Not a rare bird, but a nice set of images of a feeding activity. Note, in particular the upward pointed heads and the gaping red mouths with agitated wing flapping by each of the youngsters trying to say “feed me, not the others”.
… and the squirrel? We have two species and four shades of squirrel in the garden. Reds (aggressive chaps who rule the place) and three colours of greys/grays … there are the basic grey (gray) squirrels, several of the more and more common black variety and one or two very pale creamy coloured ones. These are actually rather handsome fellows – leucistic, not albino due to a fairtly common, spontaneous mutation of one or more of the genes that control the use of the pigment (melanin) gene, not actually mutants of the melanin gene itself. Instead of being produced in skin/hair cells and the eyes, the pigment is only produced in the eyes.
This colour business is interesting – there is another variant (quote):
It is not uncommon to observe a tan, ochre, or “blond” Eastern Gray Squirrel. This condition is thought to occur when eumelanin (black/brown in color) is “diluted” by a proponderance of phaeomelanin (yellow/red in color). There is some question as to whether the difference in color is due to an actual difference in the pigment polymers themselves or the protein matrix in which they are embedded (in the so-called melansome, an enlarged vesicle produced by Golgi bodies filled first with the protein matrix into which the polmerized pigment is later added). The usual stated chemical difference distinquishing the two pigment complexes is the presence of sulfur in phaeomelanin when the amino acid cysteine is readily available. Cysteine is the only sulfur bearing amino acid (amino acids being the building blocks of proteins). Sulfur bearing amino acids are capable of forming S-S cross bridges. Such availability of cysteine thus might be expected to change the nature of the protein matrix in which the pigments are embedded due to these cross bridges. According to Searle (1968), the protein matrix associated with the phaeomelanin complex is more condensed and less well organized than that which we refer to as eumelanin. The resulting change in the physical shape might account for the color shift. Any number of gene subsitutions (mutations) might account for this and it is surprising that this variant is not observed more often.
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