Sometimes I wonder what Charles Darwin might say about the current culture of wildlife rehabilitation. A recent episode in Portland, Oregon made national news and sparked some local debate surrounding human interventions when wild animals seem to be imperiled. 

On the morning of 3 March 2014, two adult Bald Eagles were found entangled in the branches of tree in a southeast Portland neighborhood. They seemed to be locked together by the talons and unable to free themselves from either the tree, or one another. Frantic onlookers made phone calls the local Audubon Society rehabilitation center, the U.S. Fish and Wildlife Service (USFWS), and the Oregon Department of Fish and Wildlife (ODFW). Many of those onsite believed that the eagles were gravely injured and that they would need to be captured and rehabbed. Eventually a bucket truck with a "cherry-picker" arrived on the scene. Lacy Campbell of the Audubon Society of Portland rehab center and another wildlife veterinarian loaded into the bucket and were raised up to help the eagles free themselves. As the rescuers drew near, the eagles became increasingly agitated and broke free on their own. They flew off over the housetops, apparently no worse for the wear.

These two adult Bald Eagles spent several hours stuck together in a tree in southeast Portland, Oregon on 3 March 2014. How they ended up here is a matter of speculation. (image sourced online at http://koin.com/2014/03/03/eagles-stuck-together-se-portland-tree/ )

In the aftermath, various television stations and news outlets reported that the eagles were "fighting" (KOIN) and that one of the eagles had apparently lodged a talon in the thigh of the other. Otherwise, there were no outward signs of injury. It is well known that courting pairs of adult eagles clasp talons and do "death spiral" drop,  plummeting hundreds of feet before releasing. This courtship ritual has resulted in injury and death when eagles failed to break their grasp before hitting the ground. Some who viewed video clips of the entangled eagles believe that these birds may have been a mated pair that ended up stuck in the tree at the end of courtship spiral, rather than two adult males fighting over territory. Studies of Bald Eagle territorial disputes suggest that actual physical contact is rare. (http://bna.birds.cornell.edu)

My question is this, if these eagles found themselves in this predicament as a result of typical behavior–there is no reason to think otherwise–was human intervention appropriate and did it ultimately benefit the species? I believe that Darwin's answer would have been no! 

Let's reconstruct this scenario. What would have happened had these birds become stuck in a tree far from human habitation in the nearby Coast Range or the Mt. Hood National Forest?  There would have been no intervention. Perhaps these birds would have never become quite frightened or panicked enough to extricate themselves. Perhaps they would have succumbed to starvation and removed themselves from the gene pool. We have no way to know how this episode would have played out sans the human intervention. Could it be that one or both of these eagles was afflicted with eyesight or depth perception issues that contributed to their entrapment? If so, could it be that human efforts saved these eagles from their own deficiencies? If they reproduce, could these deficiencies be passed forward rather than being naturally selected out of the population by their death? In theory, this rescue effort may have weakened the local Bald Eagle population by contributing to the survival and reproduction of less-fit individuals.

I believe that the evolving culture of 'wildlife rehabilitation,' a comparatively recent addition to the human experience, may be reinforcing one negative aspect in the way many humans view wildlife. We find baby birds and animals to be cute and endearing and we project onto them those qualities of helplessness and need for tender care that we see in our own offspring. Unfortunately, we are in no position to know or understand what is best for the offspring of other species. Rather than observing and attempting to better understand the natural interactions of wild animals, the first inclination for some is to believe that they have a role to play when these interactions result in peril to individuals. The knee-jerk response seems to be, "I need to do something" or, "I need to help." In most instances, the best course of action may be to do nothing and to avoid trying to provide help or rescue. 

Prior to about the 1960's, the notion of a wildlife rehabilitation center was a foreign concept. Then in the late 1960's and early 1970's high-profile offshore oil spills resulted in thousands of beached oiled seabirds (http://www.angelfire.com/nj/woundedknee/rehabhist.html). What had been truly a cottage industry conducted by individual nature lovers in their own homes–mostly raising baby birds or adopting injured squirrels–now required a coordinated response of considerable scale. Protocols and facilities with paid staff cropped up to deal with this 2oth century threat to wildlife and in 1982 the National Wildlife Rehabilitators Association was formed to bring professional standards to this work (http://www.nwrawildlife.org/content/history-nwra). Most would rightly argue that in cases of anthropogenic impacts on wildlife a human response is not only appropriate, but morally obligated, thus for this purpose the existence of wildlife rehabilitation/treatment centers is warranted. 

Thankfully, catastrophic environmental disasters aren't everyday events, but they still occur with enough frequency that there is a need to maintain these facilities for those occasions when they are most needed. Generally speaking, wildlife rehab centers are independent non-profit entities, or part of a larger non-profit organization (i.e. the Audubon Society of Portland's Wildlife Care Center). Underwriting a facility, care materials and a modest trained staff carries a significant cost, all of which must come from donations and grants. How then do these care centers recruit volunteers/supporters and raise money?

One element to any successful fund-raising effort is tugging at the heartstrings of potential donors. From the smiling Girl Scout selling cookies in front of the local grocery store, to informercials about starving kids in the Third World, we are shown a need and asked to respond to it. For wildlife rehabilitation centers, this connection is made by offering a place to take the baby bird that you find in your backyard. If you had to pay $100 to drop off a fledgling Song Sparrow, you probably wouldn't, but the experience of being able to do so at no cost may inspire you to make a tax-deductible $100 donation once a year for several years. Ironically, care centers discourage the activity that probably connects them with most of their future donors. The fine print on their websites generally advises against doing what many people will do when they encounter wildlife in apparent distress. The instructions below appear on the Audubon Society of Portland's Wildlife Care Center website.

Many species of birds such as robins, scrub jays, crows and owls leave the nest and spend as many as 2-5 days on the ground before they can fly. This is a normal and vital part of the young birds' development. While they are on the ground, the birds are cared for and protected by their parents and are taught vital life skills (finding food, identifying predators, flying).  Taking these birds into captivity denies them the opportunity to learn skills they will need to survive in the wild. Unless a bird is injured, it is essential to leave them outside to learn from their parents. (Sourced online at http://audubonportland.org/wcc/urban/babybirds)

As it is, hatch-year mortality in birds is extremely high, even when everything goes right. Once a fledgling is 'rescued' and removed from the natural world for a even a brief period, it's hard to imagine that its prospects can be good once it's returned to the wild. As suggested above, the one-time opportunity to acquire requisite survival skills is lost and vital lessons can never be learned. When humans see a baby bird on the ground they typically make one of two faulty presumptions...that it has either fallen from a nest before actually fledgling, or that it has been abandoned. Typically, hatclings are on the ground because they've fledged but can't yet fly and their parents are either off gathering food,  or sitting patiently in a nearby bush waiting for the potential threat (us) to leave the area. 

Imagine finding this days-old Yellow Warbler on the ground with no adult in sight. It barely has a tail, is just starting to develop flight feathers, and can barely maintain its perch on this Armenian Blackberry branch. It would be easy to assume that it is in distress, but is it? I wouldn't have been able to identify this bird to species had it not been for the presence of its parents. The adult male flew in landed mere feet away before I even got out of the car. He chipped incessantly for nearly a minute until I finally noticed the motivation for his excitement. Meanwhile, the adult female quietly continued gathering food and taking it to this newly-fledged youngster and at least one other that was presumably still in the nest. (Photo by Dave Irons)

Ultimately, most all of wildlife behavior that we observe is what the birds and animals are supposed to be doing and part of their natural history. It may be stressful and unpleasant to watch and there may be an urge to respond to apparent suffering. However, unless that suffering has been brought about by some human action, nature should be left to take its own course. There are hard-wired biological and survival mechanisms at play that we don't recognize, or fully understand. Trying to help is more likely to hinder. 

It's not easy to set aside our human emotions and avoid applying our own value systems and judgments to natural events. I don't have ready answers to some of the questions that I've raise about wildlife rehab/care centers. On occasion, they provide a necessary response to problems that we humans have created for wildlife. They are also instrumental in helping humans appreciate and better understand the natural world. That said, I have to wonder if their very presence reinforce predictable human emotional responses that may be detrimental on a broader scale.  What are the effects of 'rescuing' a baby bird that has neither fallen out of a nest, nor been abandoned, or allowing adults that may be less fit to survive and reproduce?  

While this dull Cassin's Vireo, photographed in Wasco County, Oregon on 2 June 2013, appears to show the slightest olive tones in its plumage in this image, seeing any greenish or yellowish coloration in the field was quite difficult. (Photo by Dave Irons)

Since the Solitary Vireo was split into three species (Blue-headed, Cassin's and Plumbeous Vireos), birders have struggled to separate these taxa when any one of them is reported outside of its normal range. In the Fall, separating putative Blue-headed Vireos on the West Coast is complicated by the fact that freshly-molted Cassin's Vireos are nearly as bright, colorful, and contrasting in plumage (Heindel 1996). Similarly, a suspected Cassin's Vireo found east of the Rocky Mountains must first be proven not to be a Blue-headed. 

Vireos sport their brightest and most contrasting appearance in the Fall after going through their only molt cycle of the year. Like other vireos, Cassin's Vireos seen during Spring and Summer can be quite dull and virtually colorless. The contrast and color one sees in the Fall are lost to feather wear and fading. During this season, it's hard to imagine how a Cassin's might be confused with a Blue-headed, but Plumbeous...that's another story. 

One of the by-products of any species split is a predictable surge in reports of the new species from locales where the former subspecies was either never, or rarely recorded. Trying to get a handle on the actual status and distribution of the new taxon can be a challenge because the first wave of such sightings comes before field guides catch up and authoritative ID articles are published. As we rush to fill the blank spots on the new scorecard, we do so without the help of well-vetted resources. Most birders don't concern themselves with trying to recognize subspecies, but once one is elevated to full species status and becomes available for us to tick off, the sense of urgency to do so ratchets up. 

The bird in the images above and below is a Plumbeous Vireo that was photographed near San Jose del Cabo, Baja California Sur, Mexico on 8 January 2009. It strikes me as having stronger contrast at margins of the throat and seems heavier-billed and longer-tailed when compared to Cassin's Vireo. (Photos by Dave Irons)

The breeding range of Plumbeous Vireo spans most of the Great Basin–Nevada, s. Idaho, Utah, w. Wyoming, n. and e. Arizona, and much of New Mexico (Goguen and Curson 2012). The northernmost breeding records are from Montana and to the south the breeding range extends into Mexico along the Sierra Madre (Goguen and Curson 2012). Although some presume that this species breeds in Oregon, there is no clear evidence for this being the case. 

Prior to 1997, when Plumbeous Vireo attained full species status, there were but a handful of colloquial and published "Plumbeous" Solitary Vireo records from Oregon. Most were not fully documented. Additionally, no specimen taken in Oregon has ever been assigned to this form. However, with the anticipation and eventual assignment of full species status the occasional claims of a Plumbeous Vireo, which formerly came every few years or so, have mushroomed into multiple reports per year.

Most of Oregon's reports of Plumbeous Vireos have fallen late May to early June. The majority of such sightings coming from desert oases/migrant traps in the southeastern corner of the state, where visiting birders arrive primed and ready to find vagrants. Note that this section of Oregon is sparsely populated and only a handful of active birders live in this subregion. I'm not quite sure how, or why it happened, but in the wake of the species split the Oregon birding community quickly came to accept that Plumbeous Vireo should be expected in southeastern Oregon at this time of year and that it probably breeds semi-regularly in this corner of the state. The evidence supporting either of these notions is at best, scant. There are but seven reports of Plumbeous Vireos that have been accepted by the Oregon Bird Records Committee (OBRC). Four of these are single-observer sight records and only two of the seven accepted records are supported by photos.  

Here's another angle showing the June 2013 Wasco County bird (same as pictured at the top). When this bird was inside the canopy and backlit, it looked entirely gray. In this image, there appears to be the slightest tinge of green on the flanks just below the upper wing bar, otherwise it is gray and white. (Photo by Dave Irons). 

The species account in Birds of Oregon: A General Reference (BOGR) may have contributed to the misunderstanding of Plumbeous Vireo's status in Oregon (Nehls 2003). It starts by stating that the status of this species is "poorly understood." Then, there is a cautionary note about identification, which references Matt Heindel's excellent ID article published in Birding (Heindel 1996). It further points out that there are no Oregon specimens. Following these caveats, there is a roster of 11 cited records, including a putative nest found along Kelly Creek in southern Lake County in 1996. Apparently, the nest site was logged shortly after this discovery, thus no further documentation or photos were obtained. The account also offers that the species "has been reported in Harney County every spring since 1992." It's hard to read this account and not come away believing that the regular occurrence of Plumbeous Vireo in Oregon is well established. Many of the reports listed in BOGR (Nehls 2003) were never submitted to the OBRC and of those that were, two were not accepted. 

The issue with over-reporting of Plumbeous Vireos is not confined to Oregon. In California, ballooning spring reports of this new species from that state's coast and desert oases have also raised questions (Paul Lehman pers. comm.). According to Lehman and others, Plumbeous Vireos are still "scarce-to-rare" during Spring even in Southern California, despite an apparent increase in the numbers found there during fall and winter. Away from Southern California (Los Angeles south) Plumbeous Vireos are casual visitors at any season. Long-time North American Birds regional editor Guy McCaskie is of the opinion that there are only a few "ironclad" spring records from Southern California and that all good records are from the desert, with coastal reports being suspect (Lehman pers. comm.). As they have been in Oregon, reports from California's desert outposts are often poorly documented, as many birders believe that a spectacled vireo seen in desert/Great Basin habitats is by default a Plumbeous. From Oregon, Alan Contreras points out that northbound Cassin's Vireos continue to trickle through Harney County oases into early June, even though this species is not thought to breed in Harney County, or neighboring Malheur County to the east.  

On 30 May 2010, three other experienced observers and I chased this bird around the oasis at Fields, Harney County, Oregon for nearly a half an hour. Until I captured this flight shot, which clearly shows a greenish wash along the flanks, we were convinced that the bird had no greens or yellows in its plumage. It spent most of its time in the shade and only showed tinges of green and yellow when it came out into direct sunlight. Even then it was a challenge to see these colors. (Photo by Dave Irons)

When seemingly credible sources repeat the same thing with enough frequency, claims that lack hard supporting evidence gain traction and start to become accepted 'fact.' Political parties are experts at this sort of manipulation of reality, often swaying public opinion with the repetition of half-truths, or murky data.

The birding world is not immune to being influenced by apparent critical mass. Unlike the manipulation that occurs in the political arena, birders tend to unknowingly perpetuate fallacies. When visiting sites where vagrant birds are found regularly, or birding a locale where a desired species is "expected," it can be a challenge to avoid the pitfalls that accompany expectation. Objectivity and healthy skepticism are too often replaced by an excited mind that is ripe for being duped. It's not hard for us to shoehorn the first plausible candidate into a species that we are hoping to see. It becomes easy to overlook what one subconsciously doesn’t ‘want’ to notice and see only those aspects of the bird that seem to best fit the species that one hopes to add to their list. If you’ve been birding for any length of time, you’ve probably stepped into this pothole a time or two.  

When birding desert migrant traps in southeastern Oregon–where Cassin's Vireos are low density spring migrants–the sight of an apparently dull and colorless spectacled vireo gets the blood pumping. If the bird stays inside the canopy and out of direct sunlight (typical for this species group), it's not going to be difficult to convince yourself that you aren't seeing yellows and greens in the plumage, because you probably aren't. Even knowing how dull Cassin's can be in the spring, I have twice been fooled into thinking that I might be looking at a Plumbeous in Oregon, only to have my camera or exposure to direct sunlight reveal color that I wasn't seeing when the bird was in the shade. Even in good light, the subtle colors of a spring Cassin's come and go with changes of angle. 

At this point, the actual status of Plumbeous Vireo in Oregon remains a mystery, in part because our birding community has applied little rigor to the examination of reports of this species. Acceptance of a presumed status is based almost entirely on a set of unreviewed or undocumented reports, hence there is a prevailing notion that reports of this species don’t require thorough documentation. I contend that we should start from ground zero and start treating Plumbeous Vireo as though this species is extremely rare in Oregon, which it may well be. Only then, will we be able to get a handle on their actual status. Getting that genie back into the bottle is easier said than done. 

Literature Cited:

Goguen, Christopher B. and David R. Curson 2012. Plumbeous Vireo (Vireo plumbeus), The Birds of North America Online (A. Poole, Ed.) Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell,edu/bna/species366 doi:10.2173/bna366

Heindel, M.T. 1996. Field identification of the Solitary Vireo complex. Birding 28:458-471. 

Nehls, H. B. 2003. Plumbeous Vireo. p. 401 in Birds of Oregon: A General Reference. D.B. Marshall, M.G. Hunter, and A.L. Contreras, Eds. Oregon State University Press, Corvallis, OR.