It's now a decade since I was looking here at colours in nature, and red was one of the more obvious ones. I doubt that many people reading this were also reading back then, and I'm very sure that no-one remembers it! However I have no interest in just recycling old posts, but a lot of interest in revisiting interesting topics with the benefit of the intervening years, and a lot more photos. So here is a glowing new post on red in nature - specifically birds' feathers for now at least. It will be the first in a short series.
Male Crimson Chat Epthianura tricolor, central Australia, carrying a grasshopper to feed chicks. This bird glows red! |
The chat, like almost all other birds, can't manufacture the carotenoid pigments which give it the exquisite colouring, but must extract them from its food and store them in its liver until the new feathers are produced at the next moult, when the pigment is incorporated. This is an energy-intensive process, to the extent that hardly any birds are all-red. Nor is the chat getting its red glory from the grasshopper - the carotenoids (and there are many different ones) are produced by plants, which the bird acquires especially from berries, flowers and seeds. In the chat's case, it is probably mostly from seeds.
It is relevant too that only the male chat is red; she is plain brown with a pinkish wash. As I said, it costs a lot to produce the colour, and she doesn't have to impress anyone - he must make a statement about his fitness, and all she does is assess his application. Her criterion is the intensity of his colour, which is effectively a measurement of his health and vitality; "I'm so fit that I can afford to spend a lot of spare energy simply in order to look as gorgeous as possible".
A few waterbirds do get their carotenoid dose from animals (especially brine shrimps) but these in turn get them from algae.
Flamingo chicks hatch a dirty white colour and only turn pink/red after being fed shrimps, and after their first moult. Captive flamingoes must be fed Astaxanthin as a food supplement, or they will fade after their next moult.
(I have so many examples to choose from for this series that I'm going to concentrate on birds that are really red - or at least partly so - rather than pink or orange; I reckon that this flamingo has enough real red to qualify. The story that comes with it helps it to qualify too.)
Scarlet-backed Woodpecker Veniliornis callonotus, Sipan, northern Peru. This is a bird of the dry woodlands of the Pacific coast of southern Colombia, Ecuador and northern Peru. |
Since hardly any birds can be all red, they must use other colours as contrast; somewhat unusually, this woodpecker has 'chosen' white. Green is a popular option, but the most striking and widely used versions contrast red with black, which is based on melanins that the bird can readily manufacture. The woodpecker above has a fringe of black along the wing edge, and a black tail; the female also has a black cap. So prevalent is this contrast that I am going to feature black-and-red birds in their own forthcoming post.
Not quite all birds however are reliant on diet-based carotenoids for red colouring. Parrots alone can synthesise a quite different group of pigments called psittacofulvins or, more simply, psittacins, to produce reds, oranges and yellows. It's curious in that parrots have carotenoids in their blood, but don't use them as other birds do. It seems that their ancestors hadn't learnt that trick, and the parrots came up with the psittacofulvin idea after they were isolated from other bird groups. Psittacofulvins produce brighter reds than carotenoids, and give greater protection against feather-damaging bacteria. Because these psittacofulvins are apparently cheaper to produce, parrots can afford to be more profligate with them, but of course they can't afford to look too much like everyone else so don't simply daub themselves all in red.
So, if being all-red is just too extravagant to be a viable option, where do birds wear their show-off red feathers? Since there's no single simple answer to this, I tried putting the pictures I'd chosen into categories. One obvious place to bring your very-redness to others' attentions in an unmissable way is on the head, and several of my subjects do just this in examples from three continents.
Red-and-green Macaws Ara chloropterus, Blanquillo Clay Lick, Peruvian Amazonia. In these spectacular big parrots the red covers most of the front of the body too. |
Red-and-yellow Barbet Trachyphonus erythrocephalus, Amboseli NP, Kenya. There's no doubting the redness of the cheeks, but the crown is black and white. |
Male Red-headed Barbet Eubucco bourcierii, Bosque de Tolomuco in the central mountains of Costa Rica. She has a more affordable yellow head with blue cheeks. |
Other quetzals tend to get overlooked by comparison, but this Golden-headed Quetzal Pharomachrus auriceps in the Mindo Valley of northern Ecuador is far from shabby too. |
Other birds have red underneath which is much more obscure, being low on the belly or just comprising a bar or patch.
Eastern Double-collared Sunbird Cinnyris mediocris, cental Kenya. Another bird with just a narrow red breastband; again contrasted with green. |
Here are two more Australian parrots with red just on the belly or vent, so mostly only visible from below.
Male Mulga Parrot Psephotellus varius, Mutawintji NP, western NSW. A delightful little ground-feeding parrot of the dry inland, with red on the belly and thighs only. |
Here is another toucan, one of the big ones this time, with similar red pattern - belly (though all of it in this case) and rump.
Green-billed Toucan Ramphastos dicolorus, Trilha dos Tucanons, near Sao Paulo, Brazil. Above and below. |
This flash of red rump allows me to introduce what I'm describing as the fourth type of use of red (after most of the body, featuring the head and featuring the breast). This involves a small highlight, perhaps a spot or a small blaze or flash of red. Not too much energy is involved in producing those relatively few red feathers but its effect is undoubted; that highlight stands out disproportionately to its size. Well it does to me anyway; perhaps it doesn't to you, and who knows how it appears to the birds, the only ones who really matter here? However there must be a purpose to it and we do know that birds see red well. And quite subjectively I do like the understatedness of some of these 'flashes'.
Here are a few more red rumps on display.
Male Spotted Pardalote Pardalotus punctatus, through my study window - he was attacking spiders in their webs in the corners of the sliding doors. Just a hint of red rump here, merging into orange. |
But there are no rules to say that a red rump precludes another red spot or so elsewhere. Here are a couple of Australian grass finches (Family Estrildidae) to model this option.
Blaze-winged Parakeet Pyrrhura devillei, southern Pantanal, Brazil. In addition to the tiny shoulder spot of red, they have red underwings too. |
This lovely pipit is a Rosy-throated Longclaw Macronyx ameliae, here in the grasslands of Ngorongoro Crater, Tanzania. The red (or pink or orange) little throat patch really stands out. |
Finally for today the Neotropical tanagers are one of the most colourful groups of birds in the world, but red doesn't feature heavily - except when paired with black, which is where we'll meet some more in a future post. Here's a beauty from Brazil which favours an obvious red neck.
Red-necked Tanager Tangara cyanocephala at Espinheiro Negro, south of Sao Paulo. |
That's probably enough red for now, but there's plenty more to come! Next time I want to explore how birds use red pigments that aren't in feathers - in skin, legs, beaks and eyes. Hope you'll be back for that!
NEXT POSTING THURSDAY 4 MAY
I
love to receive your comments and in future will be notifying you
personally by email when a new posting appears, if you'd like me to. All
current subscribers have been added to this mailing list and have
already been contacted. This will mean one email every three weeks at the current rate of posting. I promise never to use the list for any other purpose and will never share it.
Should you wish to be added to it, just send me an email at calochilus51@internode.on.net. You can ask to be removed from the list at any time,or could simply mark an email as Spam, so you won't see future ones.
Should you wish to be added to it, just send me an email at calochilus51@internode.on.net. You can ask to be removed from the list at any time,or could simply mark an email as Spam, so you won't see future ones.
2 comments:
Another fascinating post. Thanks Ian.
KathH
Thanks Kath, I always appreciate your feedback. Hope you enjoy part two as well! IF
Post a Comment