Red Birds Rock It#2: from beaks to feet

In my last post I explored how, why and where some birds have red feathers. The same carotenoids have been harnessed to make other body parts, especially skin, also glow to create a striking effect with the same message - "I am so fit that I have lots of spare energy to spend in making these luxury pigments, with the sole purpose of impressing you".

Rainbow Lorikeet Trichoglossus moluccanus, Emerald Botanic Gardens, central Queensland.
Not only does this spectacular though common (and rapidly spreading) parrot have gorgeous
red-orange breast feathers, but a lovely red bill as well. The bill structure is made of bone - it is derived
from reptile jaws after all - but the covering is not skin (which is made of collagen) but a tough
layer of keratin, like scales and feathers.

Here are some more birds with carotenoid-enhanced bills. It was a revelation to me to find that in almost every case (across ten Orders of birds), both bill and legs/feet were enhanced in the same way. While the skin itself is formed of collagen, the scales that cover the legs and feet are of keratin, like the bill sheath. (Though as we'll see later in this post, collagen can also be bright red.) I've also just noticed that all of these example are non-passerines; I'm not sure what, if anything, I should make of that. We saw in the last post that passerines have no trouble in producing red feathers.

 

Dolphin Gull Leucophaeus scoresbii, Ushuaia, Argentinian Tierra del Fuego, a beautiful
gull from the shores of the far southern cone of South America.

Silver Gull Chroicocephalus novaehollandiae, an abundant gull around the coast
and in any suitable inland habitats of Australia. The missing leg is not unusual, and
could be the result of predation (including large carnivorous fish) or fishing lines.

Crowned Lapwing Vanellus coronatus, Buffalo Springs NR, central Kenya, common
across southern and eastern Africa. This bird had made her nest right by the road
and was threatening us for daring to drive near them.

Coscoroba Swan Coscoroba coscoroba, Puerto Natales, Chilean Patagonia.
This is the only swan in the world that is not in the genus Cygnus and it is smaller than all
the others. There seems to be no agreed understanding of where it fits into the bigger picture,
but its beauty could hardly be challenged. It is found in the lower third of South America.

Buff-breasted Paradise-Kingfisher Tanysiptera sylvia, Julatten, north Queensland.
This beauty (what is it about red beaks and legs??) winters in New Guinea but
flies south across the Torres Strait to breed in very similar habitat, for no evident reason.

Perhaps imposing rather than elegant, this Stork-billed Kingfisher Pelargopsis capensis
  is equally impressive. This one was in Sabah, Malaysian Borneo, but it is also found
across southern and south-eastern Asia.

Red-billed Tropicbird Phaethon aethereus, Genovesa, Galápagos. The three tropicbird
species occur in tropical oceans, this one being found around the Americas, across the
Atlantic and around the Red Sea. Its feet are yellow-orange rather than red, but
carotenoids are still involved.

Australasian Swamphen Porphyrio melanotus, Canberra. Very common and familiar
here, where it often crashes urban picnics. Part of a species complex that covers
much of the world.

Red-legged Cormorants Poikilocarbo gaimardi, Arica, northern Chile.
I think this is close to the most attractive cormorant I've seen - all those red highlights again!
It is found along most of the west coast and the far southern tip of the east coast of South America.

White Stork Ciconia ciconia Serengeti NP, Tanazania, one of the numerous
species which breed in Europe and western Asia and winter in Africa. This
one is of course also taking a break from delivering babies.

Red-legged Seriema Cariama cristata, southern Pantanal, Brazil.This and the
less ornate Black-legged Seriema are the only living members of an entire Order of birds.
It is a ground-hunting predator of the great grassland plains.

Quite a few pigeons have opted for the 'red front and back' option too. Here are a couple of Australian representatives.

White-headed Pigeon Columba leucomela, Nowra, south coast NSW.
In addition to the legs and bills, this very pretty pigeon has a ring of red skin
around the eyes - more of these coming up.

Wonga Pigeon Leucosarcia melanoleuca, Beowa NP, far south coast NSW.
A mostly ground-dwelling forest pigeon of the east coast forests, and
the only one of its genus.

    And finally a couple of birds which are fairly unusual in having red legs and feet but not red bills.

Pied Stilt Himantopus leucocephalus, Port Fairy, Victoria. This pattern (red legs, black bill)
is actually true of all four currently recognised stilt species around the world. When you've
got the longest legs for your size of any wading bird, you may as well highlight them!

Red-footed Booby Sula sula, Genovesa, Galápagos, above and below.
This, the smallest species of gannet and booby, has very impressively red feet, but
a pale blue bill. Body feathers can be either white or brown but the feet,
which play in important role in courtship, don't change.

As mentioned at the start, all of these red features (I think!) utilise the protein keratin, but many other non-feathery red bits of birds use skin, ie collagen. One unusual such feature (or usually a pair of features) is a wattle (or caruncle) which is a fleshy structure, often dangly, hanging from a bird's face or neck. Here are some red wattles hanging from the throat or neck, all purely decorative. Most bearers of them are large birds, perhaps because wattles on a small bird would not be usefully visible.

Red Wattlebird Anthochaera carunculata, Canberra. Abundant across southern Australia,
it is also close to being the largest honeyeater. The fact that it is not red and has
no significant association with wattle trees confuses newcomers to Australian birding!

Dusky-legged Guan Penelope obscura, Peruibe, south coastal Brazil.
Other guans - in the Neotropical family Cracidae - also have wattles.

Grey Crowned Crane Balearica regulorum, Ngorongoro Crater, Tanzania.
A spectacular crane found across much of eastern Africa, it is also the national
bird of Uganda.The wattles are inflatable sacs which feature in display dances.

Southern Cassowary Casuarius casuarius, Mount Hypipamee NP, Atherton Tablelands,
tropical Queensland. The bright colours and long wattles (which can be up to 18cm long)
suggest that this is a female, which is also a lot bigger than the male.

And here are some wattles growing by the eyes.

Wattled Jacana Jacana jacana, northern Pantanal, Brazil. They also sport an associated
big red frontal plate above the bill.

Wild male Muscovy Duck Cairina moschata, also in the Pantanal. This duck is found
throughout much of South and Central America, though not commonly now,
as it is heavily hunted and thus very wary. The caruncles on the face vary
but this pattern of beading around the eyes is typical. Females have feathered
faces, few if any caruncles and lack the prominent crest. Domesticated birds
vary in plumage, many being white.

Finally, a most unusual wattle, which is stiffly erect rather than dangling or warty.

Comb-crested Jacana Irediparra gallinacea, Kakadu NP, Northern Territory.
Some other birds, including domestic fowls, have such a comb, but theirs is
soft and floppy. (While not the subject of today's post, it would be remiss
of me not to point out the jacana's amazing toes that spread their weight so it can
be borne by the lily pads.)

A lot of birds have an area of bare skin around their eyes, often coloured red, which probably gives information about the fitness of the wearer. We begin with a couple of pigeons.

Bare-faced Ground Dove Metriopelia ceciliae, northern Chile.
This is mostly a bird of arid mountains.

Speckled Pigeon Columba guinea, Tarangire NP, Tanzania.
A familiar and striking bird throughout much of Africa below the Sahara.

Yellow-throated Spurfowl Pternistis leucoscepus, Tarangire NP again. The spurfowls are
a group of francolins, which in turn are close to the partridges. This one is from the
day north-east of Africa. The red face skin contrasts with the bare yellow throat patch.

Blue-naped Mousebirds Urocolius macrourus, Buffalo Springs NR, Kenya.
There are six species of mousebirds, the only members of their entire Order.
This one is found in north-eastern Africa and across the arid Sahel to the Atlantic.

Banded Lapwing Vanellus tricolor, south-west Queensland. This small mostly dry country
lapwing looks very imposing, even a bit intimidating, when viewed head-on like this.

The other red-faced species I want to feature here are all large birds, three of which contrast their red faces with white feathers.

African Spoonbill Platalea alba, Lake Nakuru NP, Kenya.
This is the only African spoonbill (apart from Eurasian Spoonbills on the Red Sea coast)
and is found across most of the continent.

The American White Ibis Eudocimus albus has a similar colour pattern to the previous spoonbill;
this one was in Costa Rica.

A couple of storks follow.

Brolgas Antigone rubicunda, central Queensland. Their red face includes a throat pouch which,
like that of the crowned crane earlier, is used in the ritual courtship dance.

Maguari Stork Ciconia maguari, Pantanal, Brazil.
A big stork of eastern South America, though not in the Amazon, whose red face
intensifies in colour while breeding.

And finally in this section, one of the world's most unusual and dramatic birds of prey.
The Secretary Bird (for the quills like an old-time scribe's behind the ears)
Sagittarius serpentarius, stalks the grasslands of most of Africa, hunting insects and
reptiles in particular, but also any birds and mammals they can catch.
I assume that the distinctive face patch has a role in courtship
but I can't find any information on that.

Which brings us to the last red topic for this post; that of eyes. By this we usually mean the iris, though sometimes it is used loosely to describe the skin around that eyes that we've just looked at. When I was first doing some reading for this post I found an assertion that the carotenoids which produce red colours in birds' feathers and skin are not found in the eyes, but that red eyes are the result of pteridines. I should have been more suspicious of such a simple and blanketing assertion regarding nature and in fact both assertions are incorrect. There is a lot we don't know about red-eyed birds, but a good start is in this very recent paper, available on line (Corbett et al 2022).

Here are a couple of examples that have been examined (as per Corbett et al) as examples of the complexities involved. (There is more information in Supplemental Appendix 3 of the Corbett paper but I can't find it anywhere; any help in doing so would be very gratefully received.)

A Black Swan's red eyes (Cygnus atratus, here in Canberra) are due to a combination
of blood vessels, melanins and a reflecting crystalline structure composed of cholesterol.

The red eyes of Zebra Finches (this one the Australian species Taeniopygia castanotis,
in the Great Sandy Desert, Western Australia) have nothing in common with those
of the swan. They do however have pteridines, which here form a crystalline reflective
surface; however, other pteridines can form non-crystalline pigments!

And that's probably enough complexity for today, especially as we still don't know so much. Let's conclude the post (which is already very long, I freely admit) by just admiring a few more very attractive red eyes.

Fire-eyed Diucon Pyrope pyrope Torres del Paine NP, Chilean Patagonia.
These irises are really red (like the other species here!). This is a fairly common
New World flycatcher of cold southern Chile and adjacent Argentina.

Metallic Starling Aplonis metallica, Cairns, north Queensland.
Quite a few starlings have such near-manic red eyes.

Red-billed Oxpecker Buphagus erythrorynchus (left) and Yellow-billed B.africanus
searching a giraffe for ticks, Serengeti NP, Tanzania. I find it interesting that both their
bills contrast with their eyes (though the yellow bill of the red-eyed Yellow-billed Oxpecker
also has a red tip). These are the only two members of their family, which is related to starlings.

Tasmanian Native Hen Tribonyx mortierii, near Hobart. This large flightless rail
survived in Tasmania in the absence of Dingoes (and later of foxes).

White-winged Choughs Corcorax melanorhamphos, Canberra. These highly communal
mud-nest builders are one of only two members of their Family (with the Apostlebird,
another old Australian). Their staring red eyes bulge - I assume with blood - when
they are presenting their threat display to an intruder (me, in this case).

And that will do for today I think! I hope you're still reading (or at least looking at the pictures...). I'll leave the red theme next time but will return to it soon - possibly the one after next - to finish with the promised red-and-black post. The choughs give a good example of the effectiveness of that juxtaposition. 

Meantime, keep your eyes out for further examples of how birds wear red in your part of the world. I'm happy to hear from you any time.

NEXT POSTING THURSDAY 18 MAY

 

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