Albinism in Animals

Science class taught us that the traits of the parents get passed down to their offspring.  For example, two people who have genes for brown eyes will mostly likely have brown-eyed children.

A Leucistic American Goldfinch (photo: Gay Schroer)

But what happens when two perfectly normal parents produce an albino offspring?  Albinism is caused by a genetic mutation that prevents the development of melanin, the pigment that colors our eyes, skin, and hair.  That lack of pigment causes albino animals to appear entirely, or at least mostly, white, and have pale blue or pink eyes.  Some animals are naturally white, like Mute Swans for example, but only albinos will have the pale eyes.  Animals that depart from their normal coloration and have some white on their body, but not completely white, are leucistic.

In the wild, being albino can cause a variety of problems. The white coloration causes the animal to stand out, making it easier for potential predators to spot. However, the white coloration might also make the animal unrecognizable as a prey species.

Another issue caused by albinism is that members of the albino’s own species may reject it. Albino animals, especially birds, may not be able to find a mate because they lack the coloration and patterns necessary to catch the eye of the opposite sex.

A wild Albino Barred Owl (Photo: Kelly Bietsch)

Albinism also affects eyesight. Melanin helps in the development of the eye, and animals that lack melanin often have poor vision. An albino’s eyes are often more sensitive to light, less able to distinguish color, and less able to perceive depth. It is possible that an albino animal would have more trouble finding food or seeing danger, thus decreasing its chances of survival.

In the wild, albinism is not common. The frequency of albinism occurring varies from species to species, but generally albinism is more common in birds than in mammals. According to the Missouri Department of Conservation, albinism occurs in approximately one out of every 10,000 mammal births, while approximately one out of every 1,764 birds is albino. Although most, if not all, species can produce albinos, the only commonly albino species are those that are domesticated. Many people like to have albino pets, whether it be a cat, snake, or rat.

Kahn, WBS's albino Burmese Python (photo: JoHanna Burton)

At the World Bird Sanctuary, we do have a couple of albino animals. One of the most popular animals (depending on how you feel about snakes) is Kahn, our albino Burmese python. A normally pigmented Burmese python is patterned tan and dark brown, with dark eyes. Kahn is patterned white and pale yellow, and if that weren’t enough to convince you that he is albino, you could take a look at his pink eyes.

Kahn enjoying his pool on a hot summer day (photo: JoHanna Burton)

You can come to visit Kahn at World Bird Sanctuary's Nature Center, and on warm summer days you might just find him outside with a naturalist, enjoying a refreshing bath.

Submitted by JoHanna Burton, World Bird Sanctuary Naturalist

Leucistic Goldfinch

This seems to be my year for reporting sightings of white birds!

In December 2011 I belatedly reported a good friend’s sighting of a rare albino Barred Owl that occurred in the fall of 2010.

Rare albino Barred Owl - spotted in September 2010  

Then just recently World Bird Sanctuary Naturalist/Fundraiser, Catherine Redfern, took us along with her to Smithville Lake just North of Kansas City to view some of the Snowy Owls that have been spotted there as part of the unusual Snowy Owl irruption this year.  To read about this rare occurrence Click Here. 

One of the Snowy Owls seen at Smithville Lake in Missouri

To put the icing on the cake, just recently I was excited to see a most unusual bird at my thistle feeder—a leucistic Goldfinch! 

The leucistic Goldfinch who has been a fairly regular visitor to my feeder this winter

To my amazement I began seeing this unusual visitor on a fairly regular basis about two months ago.  However, until just a couple of weeks ago I had been unsuccessful in photographing this wary individual.  On the first few occasions when I saw it at the feeder it was gone by the time I grabbed my camera and changed my lens.  I had even resorted to leaving the camera, with long lens attached, sitting on my kitchen table.  (Martha Stewart would have been proud of my new creative table centerpiece.)  Of course the bird did not reappear until the camera was again safely stashed in my camera bag!   Finally, about three weeks ago, I was able to get a few photos—albeit through the two panes of glass in my kitchen window.

According to the Cornell Lab of Ornithology website, leucism is relatively unusual in birds, and from 2000-2006 Project FeederWatch participants reported fewer than 1,000 leucistic birds out of approximately 5.5 million birds reported each season!  I feel extremely fortunate to have seen this rarity.

Without the normal coloration it is difficult to differentiate between male and female

What is a leucistic bird you may ask—and how is it different from an albino bird?  Although there is some disagreement in the scientific community as to what constitutes the differences between these two mutations, all the experts seem to agree on one point—albinos have pink eyes and leucistic birds have dark eyes.  Albinism is a genetic mutation that prevents the production of melanin in the body, whereas leucism is a genetic mutation that prevents melanin from being deposited normally on feathers.

However, the above definition is a simplistic answer to a much more complicated question, since there are varying degrees of albinism and leucism.  To learn more about this fascinating subject click here. 

Don’t forget to keep your feeders filled this winter--you never know who might visit!

Submitted by Gay Schroer, World Bird Sanctuary Volunteer/Photographer

Have You Seen This Great White Hunter?

 In September 2010 I received an excited phone call from a friend’s daughter who lives in an undisclosed rural area of  Missouri.

On her way out of her neighborhood, with her children in the vehicle, she spotted what appeared to be a large white bird perched atop a road sign.  As she drew closer she realized, to her amazement, that it was an owl.  Neither my friend nor her daughter, are avid birders.  Beyond the fact that it must be an owl, she had no idea what she was seeing.  So, she called the only person she could think of who was really “into” birds—me.

When I picked up the phone I could tell my friend was REALLY excited!  She kept repeating that she was “….looking at an owl and it’s really, really, white!  What is it?”  The thought that it could be an albino fleetingly crossed my mind and was immediately discarded because I know how rare they are.  I began by asking the standard questions.  How big is it?  Does it have ear tufts (the feathers on the head that resemble little “horns”)?  What is its general body shape? 

A Great-horned Owl, the largest owl native to Missouri -- note the ear tufts 

Of course, to someone who is not accustomed to seeing owls in the wild at all, things like size and body shape are very subjective matters.  The closest we could get to an accurate description was the fact that there were no ear tufts and that it was “big”.  This ruled out two of our state’s most common native owl species—the Great Horned Owl (the largest) and the Screech Owl (our smallest native owl), both of which have ear tufts.

  An Eastern Screech Owl, the smallest owl native to Missouri -- note the ear tufts

That left the possibility that:

            a)  It could be a Snowy Owl that had wandered this far south (a very rare occurrence)

            b)  It could be an albino or leucistic Barred Owl (an incredibly rare occurrence)           

c)  It could be an extremely light colored Barn Owl that under dim lighting conditions could seem white (the most likely scenario) 

 A Snowy Owl - a rare and infrequent visitor from the North 

Since my friend had rarely seen owls in the wild I told her I was inclined to believe that the light colored Barn Owl was the most likely candidate, even though they are quite rare in eastern Missouri.  (What is it they always say about “assuming”)?   However, just to be sure I asked her to try to get a picture with her cell phone and email it to me.

An American Barn Owl - occasionally they can be much lighter and can appear white in dim light

After several days I emailed her to remind her about the photos, but when I heard no further from her I guessed that she was unable to get a photo and in the press of other things promptly forgot about the incident.

Last week (it is now December 2011) to my astonishment I received the following photo from my friend.  Her daughter had by now figured out how to email photos from her new cell phone and had sent her mother a number of photos.  When my friend saw the owl photo she immediately sent it along to me, since she knew I would be interested.

Believe it or not--this is a Barred Owl!

You guessed it!  It’s an albino Barred Owl!  So much for assumptions!  Now it was my turn to be excited!  I immediately called my friend, and this time it was my turn to babble.  I kept asking if they had any idea how rare this was!  Of course, this prompted a phone call from my friend’s daughter in which I was able to get more details about the encounter.

A normally colored and marked Barred Owl

Apparently after her original call to me in 2010 she took several photos of the owl, actually turning the car around in order to get a better shot.  The owl seemed undisturbed by the car, which indicates that it was accustomed to hunting near the roadside and considered vehicles to be just another part of its environment.  My friend stayed until it became too dark to take further photos.  She said they later saw the owl again on another occasion, but have not seen it lately.  It would be interesting to know if anyone else in rural areas of Missouri have seen this winged wonder.

Another view of our white Barred Owl showing no normal coloration in what should be his darker feathers

Just to give you an idea of how rare this is--following are some facts about albinism and leucism in birds that I found when researching the probabilities of seeing a Barred Owl of this color. 

            Leucistic -- Leucism is a condition characterized by reduced pigmentation in animals and humans. Unlike albinism, it is caused by a reduction in all types of skin pigment--not just melanin--resulting from defects in pigment cells during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells capable of making pigment.  Leucistic individuals usually have normally colored eyes.

            Albinism -- Albinism in birds is rare, occurring to any extent in perhaps one in 1800 individuals (Terres 1980). (This number includes all bird species—the ratio for owls is even greater).  A bird that is albino (from the Latin albus, "white") has white feathers in place of colored ones on some portion of its body.  This condition is a genetically inherited trait resulting when each parent has the recessive gene for albinism.  A bird that is naturally white, such as a swan, goose, or egret, is not an albino, nor is a bird that has seasonally alternating white plumage (like the Ptarmigan, a Grouse-like game bird from the far North).

This would seem to be a very straightforward definition of the condition, but as in many cases within the scientific community, there are differences of opinion among the experts as to what constitutes albinism.  All seem to agree that there are four different degrees of albinism:

°            Partial albinism in which local areas of the bird’s body, such as certain feathers, are lacking the pigment melanin

°            Imperfect albinism in which the pigment is partially inhibited in the skin, eyes, or feathers, but is not absent from any of them (this produces a very pale, almost white version of their normal body pattern)

°            Incomplete albinism is the complete absence of pigment from the skin, eyes, or feathers, but not all three           

°            A completely albino bird is the most rare, lacking any pigment in its skin, eyes, and feathers. The eyes in this case are pink or red, because blood shows through in the absence of pigment in the irises. The beak, legs, and feet are very pale or white.  (Some authorities hold that albinism affects melanin pigments but not necessarily the carotenoid pigments (any of a class of yellow to red pigments). 

If the carotenoid theory is correct, then our white Barred Owl would probably qualify as a complete albino, whereas by the above definitions he could be an example of incomplete albinism (only a close examination of his skin could truly verify this).

In all my research I found only one reference to a total albino Barred Owl, and a very few recorded references to the other three types of albinistic Barred Owls. At any rate, this beautiful bird is most certainly a rarity.

Historically, the survival rate in the wild for albino animals is not good—due to poor eyesight in bright light caused by their condition, rejection by others of their species because of their color, and their lack of camouflage (whether they are a prey animal or a predator).  However, one theory presented in a study  of albino Great Grey Owls in Finland indicated that owls seemed less affected by these problems than most other birds.  This theory holds that these nocturnal predators’ hunting success depends largely on locating their prey by sound rather than by sight.  Thus, poor eyesight in bright light is not a disability to these nocturnal hunters.

Another view showing his yellow feet and beak--this would support the carotenoid theory

Is he still out there?  If you live in a rural area of Missouri have you seen this beautiful white hunter?  If so, we would love to hear from you via our “Comments” section on this blog. 

Submitted by Gay Schroer, World Bird Sanctuary Volunteer/Photographer

References:
http://www.ncrs.fs.fed.us/epubs/owl/ALAJA&M.PDF (Albinism in the Great Gray Owl (Strix nebulosa) and Other Owls) by Pentti Alaja and Heimo Mikkola1

http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/Albinism_Leucism.htm

http://birding.about.com/od/identifyingbirds/a/leucism.htm

http://elibrary.unm.edu/sora/JFO/v036n02/p0067-p0071.pdf

Have You Seen Me?

Not too long ago, I started receiving phone calls at WBS inquiring about a “white hawk” people were seeing in the area.  

At first I thought they must have been mistaken, as there aren’t really any white hawks native to this area.  I explained that the World Bird Sanctuary has a South American species of White Hawk in our Nature Center, but assured them that it was not the same type of bird that they were seeing.  My curiosity was piqued, though, and I started doing a little research. 

Initially I spoke with our Field Studies Coordinator Cathy Spahn, who is one of our “go to” people when it comes to bird identification.  I explained the many calls I had been receiving, and asked about the possibility of a white hawk in the area.  She then led me to some information regarding leucism and albinism in birds that was very interesting.

Not long after that, I spotted what I thought to be a leucistic Red-Tailed Hawk in a tree that I pass every day on my way to WBS.  I was shocked, but as they say, seeing is believing.  I was thrilled that I had been lucky enough to see it for myself.  I began watching for this rare bird every day, and saw it several more times.  On a few occasions I tried to pull over and snap a picture, but this bird was very wary and spooked easily.  Other staff and volunteers had spotted the bird in the area, as well.  The last time that I saw this unusual bird I was finally able to capture several pictures.

Leucism in birds results from varying degrees of dilution of normal pigmentation.  It’s a genetic mutation that prevents melanin from being deposited normally on feathers.  That’s a fancy way of saying that the normal pattern and color of their plumage is very pale or washed out looking.  There are also birds with pied leucism, which have splotchy patches of white feathers on their bodies.  Neither of these are albino, which is when an animal is completely white and has red eyes.  These color variations can occur in several species of birds, including songbirds, and is a relatively common occurrence in domesticated Cockatiels—a species that has been extensively bred for color variations by humans.  Leucism is relatively unusual in most species of wild birds.

Jeff Meshach, Assistant Director of WBS, has extensive experience trapping wild raptors with both registered banders and falconers.  He saw the bird in question, too, and informed me this Red-tailed Hawk was actually a color variation of the Red-tailed Hawk called “Krider’s.”  Jeff went on to tell me he has seen even lighter colored Red-tails than the one we’ve seen that were the “Krider’s” variation and not leucistic.  Yes, the bird in question was much lighter in color on its breast, head and tail than a normal colored Red-tail for this area, but the light colors were consistent throughout the feathers.  A leucistic Red-tail, or any other bird for that matter, almost always has a bright, white feather mixed in with the normal colored feathers.  Particularly with Red-tails, as the bird ages, more and more white feathers can mix with the normal ones, and eventually most of the bird could be white.  Red-tailed Hawks, by the way, are the most variably colored of all the Buteos (genus of the Red-tail) in North America.

If you are near WBS, keep a sharp eye out, and you may be lucky enough to spot this wild wonder.  Let us know if you do.

Submitted by Billie Baumann, World Bird Sanctuary Outreach Coordinator