Dislocated Natural History

On September 12th, I received a link to an article published online by the Columbine Courier on September 6, 2016. We have published that link on our Facebook page to address the question raised about the article’s content relating to osprey having adapted an ability to “dislocate their shoulders upon entering the water, otherwise, they would damage their wings.”

If you read some of our Facebook responses, you will see that people are curious about the article, which is why I am expanding our response to deal with the osprey issue, as well as some other factual dislocations presented to the Audubon Nature Center at Chatfield State Park audience during their “100 Years for Birds” celebration.

To preface our response, a few caveats to one and all. Just because you see someone with a raptor or other wild animal in an educational context, do not assume they actually know about the natural history of the animal, or how it relates to the ecological system in which it is found.  We have seen many individuals and groups with raptors in particular, that are licensed to possess them, but are generally ignorant about any in-depth natural history facts pertaining to the species on display.  Often this is because of poorly-trained volunteers, which is why we put our docents thought a very rigorous training program, before they ever get to handle an REF raptor.  Even then, we recognize a volunteer or docent may be excused for not having all the facts at their command, since they may have little expertise when they enter our volunteer program.

In this case, however, the presenter was the Executive Director of the organization making the presentation, and one would think she would not be so sloppy in what was communicated to the Audubon audience. In her defense, it should be noted that reporters are often very inaccurate in what they report, but after corresponding with the writer of this story, I was convinced that the factual blunders did not come from the writer.

Here is the pertinent correspondence regarding the article which I sent to Corinne Westeman, the writer.

“Lastly, the presenters brought out the osprey, one of only three educational ospreys in the country. Paszek said ospreys rarely eat in captivity, but their bird was an exception because of how it was raised. The species has adapted to dislocate their shoulders upon entering the water; otherwise, they would damage their wings.”

I wrote to Ms. Westeman: “This is a quote from the article you posted regarding raptors, and specifically the osprey. Where or from whom did you get the information that osprey have adapted the ability to dislocate their shoulders? This would truly be a remarkable accomplishment of evolution, yet I cannot find any supporting documentation. Please enlighten me, and our consulting veterinarians.”

This is Ms. Westeman’s response:

“This was something that Paszek said during the presentation as she displayed the osprey. She said something to the effect of: when ospreys hit the water, they enter it with such force that their wings would shatter. And thus, they have adapted to dislocate their shoulders, briefly, so that they are able to pull them back and out of the ‘line of fire,’ as it were, when they hit the water.

I am, by no means, an expert on birds in general or ospreys in particular. This was something that was discussed during the presentation, so I wrote it down and added it to the story.

Thanks.”

I will address the dislocation issue first, as it is the most egregious piece of misinformation communicated. Click here  to understand the term dislocation, which veterinarians more often refer to as luxation.  Anyone with a basic understanding of vertebrate anatomy will realize that dislocating a shoulder is not an event you can recover from quickly and painlessly.  The same applies to a bird.  To imply that an osprey can quickly dislocate their proximal humerus from the scapula, and then quickly put it back into place, before the bird has to lift itself and/or a fish out of the water, confirms a complete lack of comprehension of avian anatomy, biology, and physics.  To imply that somehow through evolutionary adaptations the osprey has achieved this remarkable feat, while pelicans or other predatory birds have not, reveals the complete lack of understanding of the evolutionary process and avian natural history.

Perhaps the best information on this comes from the Journal of Morphology, when they published this research, Comparison of Wing Morphology in Three Birds of Prey: Correlations With Differences in Flight Behavior. The researchers, Elaine L. Corvidae,  (what a great name for a birder! ) Richard Bierregaard, and Susan E. Peters from the Department of Biology, University of North Carolina at Charlotte, published this online February 13, 2006, and compare three raptors and their flight adaptations: red-tailed hawks, Cooper’s Hawks, and the osprey.  The paper is available online behind a “paywall”, so if you want to get a copy, please e-mail us and we will send you a PDF file. Nowhere in their research do the authors refer to this remarkable ability that Paszek refers to.

Onto another dislocation of natural history education. Quoting from the article, “…brought out a burrowing owl, and Paszek said members of the species spend the majority of their time in South America.”  This is also inaccurate if you look at a distribution map of the species.  Burrowing owls in Canada and Colorado and places in between, will migrate south into southwestern states or Mexico, while the Florida sub-species stay in Florida year round as do the little owls in California.

Or how about the turkey vulture , “which Paszek said has the best sense of smell of any animal on earth. Despite popular belief, she continued, vultures do not circle anything that is dead or dying…” Since science has not studied all animals on the earth, one cannot claim turkey vultures have the best sense of smell of “any animal on earth”.  We do know that of the animals studied for olfaction abilities, turkey vultures have one of the best-developed senses of smell…that’s it.  And how they use their olfactory abilities gives rise to them circling in the air, because they follow a density gradient of gases produced by decaying carcasses.  This is similar to sharks in water smelling blood trails, which means they begin from a wider circumference and follow a density gradient into the center of the circle, to discover the source of the odors associated with death and decay.  Raptors are often seen circling in thermals in a kind of “holding pattern” over dead carcasses, especially on the African savannah.  I have personally witnessed this dozens of times.

Providing accurate natural science history information to an under-informed public is crucial when making choices that impact other living species in ways that are either negative or positive. It is incumbent on those who present themselves as “authorities” or “educators” to have a common-sense grasp of the facts and how they fit together; anything less is to betray the lives of the animals being represented.

I will end by quoting Mary Ann Bonnell, formerly the Lead Naturalist for the City of Aurora Parks & Open Space, who wrote a letter to REF years ago, “…Another important benefit of partnering with REF is your commitment to good science. It is our desire to present scientific facts in an engaging way to our audience. REF is very good about presenting well-researched, scientific information. In many cases live animal programs can become a discussion of what the caged animal eats and where it lives. In REF‘s case we know the birds will be a vehicle for understanding well-researched scientific concepts, which we hope will connect people to the natural world.

In summary, our programming partnership with REF helps us better achieve our goals and helps us reach a larger audience than we would without this partnership.”

I thank all of you following and supporting our work, while helping to expand our partnerships to understand the natural world.

Update: In an attempt to get an answer to the osprey question, I have spent considerable time doing some research on the subject looking for anything that might clear the issue up.  I tracked down Susan Peters, Ph.D from the Department of biological Sciences UNC, Charlotte, who was one of the original researchers on wing morphology quoted above.

Here is what Dr. Peters wrote: “Hi Peter, I’m not familiar with the data showing that osprey have a wider range of joint movement at the shoulder than other birds – send me a citation if you can.  True luxation or subluxation, as far as I know, is limited to joints which are not required to do much work during the action or recovery, e.g. intermandibular joint in snakes.  I find it hard to imagine how dislocation of the shoulder joint could work if that joint was then required to produce work during the movement.  If the joint is hyperextended during initial diving, that might work to decrease the drag as the bird tries to dip its body deeper into the water.  One would then expect that there are significant elastic mechanisms (ligaments and tendons) to pop the humerus back before the downstroke begins.  But you would also expect some structural mechanism to hold the humerus in place (preventing hyperextension) during normal flight.  So are there differences in the angle/direction of extension during the dive that allows hyperextension versus during regular flight that might limit hyperextension?  That might be a first good clue to look for in determining whether they do have some special mechanism in the bone/muscle structure that allows hyperextension in one direction but not in another.”   Dr. Peters submitted some additional information after conferring with other colleagues: ”  I just wanted to follow up on your question about dislocation of the wing in Osprey. I’ve looked at several films on YouTube of osprey in level flight and in diving. They do elevate the wing quite a bit as they lower their feet when diving into the water. But in looking at videos I don’t see any evidence that there’s any true dislocation. In fact looking at their behavior reminded me quite a bit of the striking behavior in owls.  They also strike with their feet pointing downward and elevate their wings to extend the feet fully as they’re striking the prey.  Their wrists nearly touch at the top of upstroke. If you look at videos of pigeons you’ll also see extreme elevation of the wings during takeoff and landing, with not only the wrists touching but the primary feathers running into each other at the top of upstroke. Again it doesn’t appear as if there’s any true dislocation going on. They simply seem to have an extremely wide range of motion in their wings. I’ve spoken with some colleagues here in Flagstaff and none of them are aware of any evidence for true dislocation either at the shoulder, the elbow or the wrist. So unless the person you’re quoting can site some actual data to support this idea, I’d say that you should stop using that term and simply talk about the extreme range of motion that these birds have.  Please look carefully at some slow motion videos of these birds on YouTube and you’ll see what I’m talking about.”

I have been looking for a citation from a credible source, so I have gone to a variety of web sites such as Cornell University, National Geographic, and numerous other sites that are renown for their ornithological research and publications.  So far, not one of them lists the remarkable ability of dislocating the humerus from the scapula as reported by Paszek and by one biologist at a rehab center, who offered no citations.  Ms. Finks (see our Facebook thread) , a biologist possibly associated with this rehab center, just asserted that it was fact, but if you read Dr. Peter’s note to me, Finks did not explain any of the actual bio-mechanics that could handle the amazing demands of popping the wings in and out in a split second, while also preventing the wings from dislocating in normal flight.  And, as a final, and what I would consider definitive professional opinion from one of the very best and most experienced raptor rehabilitation facilities and veterinary institutions on the planet, I offer this quote:

“I do not know of any credible support for the thought that ospreys normally dislocate their shoulders as a protective mechanism. From an anatomical perspective, it does not make sense. What I can tell you is that I have palpated the shoulder joints of numerous osprey and found no indication that they dislocate normally, even under anesthesia. A joint that dislocates as a normal anatomical function would undoubtedly also dislocate with manipulation with the muscle relaxation that occurs during anesthesia.

 FYI – I have seen osprey with coracoid fractures (one of the most common results of a frontal impact in a bird). In that perspective, they are no different than other raptors.”

Julia B. Ponder, DVM, MPH Executive Director – The Raptor Center:College of Veterinary Medicine, University of Minnesota

I will let our readers make up their own minds, but as far as we are concerned, there is no evidence, whatsoever, that osprey have the ability to dislocate their wings as a hunting adaptation.  We trust Paszek will correct her misinformation, and as far as the rehab facility with that information on their web site, unless they and biologist Finks have some credible citations to prove otherwise, it would help the entire raptor education effort if they also cleared up their incorrect data.

However, I am still prepared to eat crow if someone can show me some real evidence.

Peter Reshetniak,President

Updated: May 28, 2017 — 11:29 pm

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