Published On: Mon, May 25th, 2015

BACKYARD BIRDING IN MERIDA, YUCATAN AND BEYOND – SUPREME PREEN: GLANDULAR GRANDEUR

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Cherie Pittillo, “nature inspired”, zoologist, wildlife photographer, and author, explores nature everywhere she goes. She’s identified 56 bird species in her Merida, Yucatan backyard view. Her column, published on the 7th and 21st of each month features anecdotes about birding in Merida, Yucatan and beyond. Contact: all4birdies@gmail.com  All rights reserved, ©Cherie Pittillo

“You’re a pigeon.”

“What? What do you mean, ‘I’m a pigeon.’?”

“I didn’t call you a ‘pigeon.’ I said,’uropygium’, (u-row-pidge-e-um). It’s the scientific name for the rump where the tail feathers grow. A preen or oil gland exists in most birds located just above their tails in the uropygium. It’s an uropygial gland. Ironically, many pigeons don’t have them.”

“What’s the big deal about a preen gland?”

“It’s a huge deal. If you depended upon feathers

for flight,

Vermilion Flycatcher

Vermilion Flycatcher

or waterproofing,

Male Blue-winged Teal

Male Blue-winged Teal

or insulation,

Well-maintained feathers serve to insulate the body from cool or heat such as in this American Flamingo

Well-maintained feathers serve to insulate the body from cool or heat such as in this American Flamingo

or to attract a mate,

or to help protect against bacteria, fungi, lice and other feather parasites,

or to maintain the physical structure of feathers,

American Flamingo preens feathers and readjusts alignments of parts of each feather

American Flamingo preens feathers and readjusts alignments of parts of each feather

you would need a preen gland or another method to keep your skin and feathers in great condition.”

“Okay, thanks for the info. Goodbye.”

My conversation made me think about anhingas and cormorants. For decades I’ve read or heard that anhingas and cormorants lacked preen glands. I often saw these species with outstretched wings and believed what I had read.

I stood dumbfounded as I watched an anhinga at Merida’s Aqua Park use its bill to reach the preen gland and then rub the waxy substance over its body feathers. The substance contains waxes, fatty acids, fats, and water. It also seems that some secretions contain Vitamin D precursors. When the oil spreads over feathers, sunlight exposure activates the Vitamin D.

I also noticed how the anhinga used its neck and head in addition to the bill to rub across the preened chest and its back to distribute the supreme preen oil onto the head and neck. Look closely just above the anhinga tail to see the area for the uropygial gland.

Anhinga

Anhinga

Anhinga preens

Anhinga preens

As far as the cormorant, some scientists theorize their feathers are waterproof except the wing feathers which are wettable. With wettable wings the cormorant can dive deeper while the other feathers provide insulation thanks to its basic, but effective oil gland.

Neotropic Cormorant exhibits wettable wings

Neotropic Cormorant exhibits wettable wings

I’ve also seen ducks and other waterfowl smear the oil on their necks and heads, but didn’t realize what they accomplished until I slowed down to watch this time-consuming process. During preening, it’s also important to reach all the nooks and crannies, or with the flamingo, “necks” and crannies.

Blue-winged Teal rubs preen oil on body with its neck and bill

Blue-winged Teal rubs preen oil on body with its neck and bill

However, controversy exists whether waterproofing comes from the oil gland but rather that the bird straightens and fluffs dense feathers to form a water-tight surface.

And the controversy continues because the majority of birds have these grand glands, but some don’t; some have remnants, and some embryos show the glands but not after hatching. Glands are missing in emus, ostriches, cassowaries, kiwis, some woodpeckers, some doves, some pigeons, all Amazon parrots and other species. By the way, the two most common Amazon parrots in Merida, the White-fronted Parrot and the Red-lored Parrot, lack those rump bumps.

Even the gland structures vary as the waxy secretion empties onto the skin surface through one or more nipple-like projections. Some have small tufts of feathers associated with the pores and others don’t. The number of projections may vary up to 18. Check out the nub in the Squirrel Cuckoo as it squeezes it with its bill to get the secretion and then compare the different type of gland with that of the American Flamingo.

Squirrel Cuckoo prepares to preen

Squirrel Cuckoo prepares to preen

 

Preen gland of Squirrel Cuckoo

Preen gland of Squirrel Cuckoo

Squirrel Cuckoo squeezes preen gland for waxy substance to spread onto feathers

Squirrel Cuckoo squeezes preen gland for waxy substance to spread onto feathers

American Flamingo gathers preen oil from its preen or uropygial gland just above its tail feathers

American Flamingo gathers preen oil from its preen or uropygial gland just above its tail feathers

 

How do birds care for their feathers without oil glands or reduced oil glands? Some have downy feathers that break down into a feather dust. I wonder if Amazon parrots were the original feather dusters. Anyway, the dust contains a fine, white waxy powder containing the protein, keratin. Other oil glandless birds may use dust baths.

Female White-fronted Parrot uses feather dust to preen the male. Mutual grooming aids in social bonding.

Female White-fronted Parrot uses feather dust to preen the male. Mutual grooming aids in social bonding.

Red-lored Parrots use feather dust for preening. Mutual preening aids in social bonding

Red-lored Parrots use feather dust for preening. Mutual preening aids in social bonding

But wait, there’s more! Scientists in Spain studied the Greater Flamingo to theorize secretions from the preen glands enhance the plumage color during mate selection and suggest it’s the equivalent to the use of make-up in humans. Plus the courting male may twist his neck backwards to use the bill to preen feathers quickly in front of the female in a twist preen to attract her.

Male flamingo twist preens to attract a female

Male flamingo twist preens to attract a female

I think it’s safe to say that the functions of the uropygial gland differ among species and within some species. What scientists do agree is that birds spend a lot of time in maintaining their feathers whether with the preen gland secretion, powder dust or dust baths.

GO OUTDOORS TO PREEN YOUR SOUL>>>

 

DISCLAIMER: References do not agree on details about this species. Here are my resources:

Juan A. Amat, Miguel A. Rendón, Juan Garrido-Fernández, Araceli Garrido, Manuel Rendón-Martos, Antonio Pérez-Gálvez. Greater flamingos Phoenicopterus roseus use uropygial secretions as make-up. Behavioral Ecology and Sociobiology, 2010

https://dangleason.wordpress.com/avian-biology/staying-dry/

http://www.birdsofseabrookisland.org/taxa/t000d-evidence4.html

Revista Brasileira de Ornitologia, 21(3), 162-167

September 2013

 

http://www.flamingos-world.com/flamingo-social-structure

http://www.exoticpetvet.net/avian/uropygial.html

Elder, William H. Oil Gland of Birds. The Wilson Bulletin, 66, (1), 6-31, March, 1954

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  1. David Salas says:

    Thank you Cherie, , I enjoy a lot this article, I did know about it but not as you wrote, always learn from you (u-row-pidge-e-um) and this game word is great
    Thank you

  2. Cherie Pittillo says:

    Thank you, David. I learned a great deal about the preen gland and am happy to share what I found.

  3. Rainie Baille Bowie says:

    I found the info on rump bumps absolutely fascinating. And the photos are so brilliant I feel like I could reach out and touch them.

    • Cherie Pittillo says:

      Thanks so much, Rainie. I think some images are some of the most fascinating I’ve been able to photograph.

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