Category Archives: Corvid health

February 5, 2022 · 1:11 am

Butts for nuts: can crows do our dirty work (and should they)?

 

It’s no mystery that garbage is one of the most pervasive issues of our time. From oceanic microtrash to seeping landfills, people are trying to work out how to address the world’s garbage crisis with increasingly grand ideas. Corvids have long been associated with garbage, sometimes acting as agents of litter themselves, but one such idea asks if they might offer a solution.

A Swedish start up, Corvid Cleaning, is attempting to train corvids to pick up cigarette butts in exchange for food, as a means of combating the pervasive litter problem across their city. They plan do this through a machine that according to their website, they’ve already successfully ground tested with wild birds.

So, will this work and is it a good idea? In my opinion no and no, for many reasons. This whole idea rests on the premise that corvids are smart, (which they are,) but being smart and being motivated are very different. It’s not an issue of whether crows *can* learn it, but how you keep them engaged over time (the company hopes to save 75% of the city’s current cigarette clean-up costs). Having fed a lot of crows a lot of peanuts, I can tell you that the appeal of unlimited peanuts wanes drastically over time. While there might be an initial rash of participants, or at least a couple highly exuberant ones, there’s a serious question of meaningful sustainability without the introduction of a more desirable (and more expensive) food.

My skepticism here is born both from my experience with crows and the cold hard fact that this has simply never worked before. This isn’t the first time someone has tried this, but the 4th. The first was in 2008, when Joshua Klein delivered his infamous and highly misleading crow vending machine TED Talk. From there the Klein team debuted their Open Source idea for the Crow Box, a build it yourself machine that offered the chance to train wild crows to exchange found coins for food. While the no promises, DIY, community science nature of the project gets a more sound endorsement from me, to date, no one has had success with the final stage of the training process. The idea it seems, makes no cents. Next, in 2017, a Dutch start up called Crowded Cities pitched the exact same idea as Corvid Cleaning, though I assume their proprietary machine was a bit different. By December 2018 though, they tabled the idea, citing a lack of resources and an inability to, “get a clear picture of what the effects would be on crows and the environment.” That same year a French theme park, Puy du Fou, hired a falconer to train some captive rooks to pick up garbage as a stunt for the park. In that case it worked marvelously but of course the stakes are entirely different between wild and captive birds. And in between all those highly profiled efforts have most certainly been the odd successful backyard tinkerer. But what eventually plays out over and over again is that while wild crows can learn to do this, no one has ever been able to scale their success into something meaningful. And I don’t think they ever will.

For a moment though, let’s say that my skepticism here is invalidated; various corvids do consistently use the machine as intended. In fact, their intelligence and understanding of cause and effect renders them quite simply excellent at it. Without the appreciation for the purpose of their activities (cleaning up garbage) the project is liable to create two different kinds of cheaters: those that steal the food out from under the participants and those that resort to collecting their currency straight from the source, before it’s officially become garbage. I’m not sure how likely either of those two scenarios are, and in fact bearing that out is nearly worth keeping quiet and bagging this whole article simply to find out. But there remains at least one more point that compels me to keep going: I have never once seen a proponent of this idea fully tackle the very real health and safety issue at stake here.  

At the smaller end of this question are the issues associated with the maintenance of the machine itself. How do they plan to keep pests and mildew out of the food hopper? Rats would be the most conspicuous problem, but it’s the smaller stuff that might prove the most challenging. In my own hard learned lesson on this, I’ll never forgive myself for infesting my sister’s kitchen with pantry months after leaving behind a forgotten bag of peanuts. And of course like any high calorie food, nuts are liable to spoil especially when unsealed and exposed to the environment. I don’t offer this in denial of the absolutely horrendous things I’ve seen crows gleefully eat, but if you are intentionally creating a crow cafeteria you have a higher obligation to the food you are serving. Especially if you offer on your website that, “Chances are pretty good that it’s possible to put the birds on a better diet and improve their overall health with this solution.”

Which brings us now to the most obvious issue: cigarettes are toxic. For example, direct ingestion of nicotine at a concentration of 0.054ml/kg causes rapid death in birds.1 While there’s no way a crow would ingest that much nicotine simply from handling a cigarette butt (even with its mouth), there’s urgent need to understand how repeated handling of cigarette filters might impact these wild animals. And truth be told, I have very little confidence that the people behind these butts for nuts ideas understand the challenges of executing that study, though I would welcome their inquiries.

Earlier I asked two questions: will this work and is it a good idea. I suspect that every iteration of person that has come up with this idea genuinely appreciates corvids for their intelligence, is concerned with the amount of litter created by people, and believes that they’ve hit on an idea that will solve a problem that needs solving. Where I think they go wrong, however, is condensing my question into a single query where whether or not it’s a good idea is simply an artifact of whether or not the idea works. It’s the Silicon Valley mindset applied to wildlife. Ian Malcom warned us against this, and here we are ignoring him yet again.

Which leads to me to what I think is the only good idea that might arise out of a machine that trades treats for garbage. Rather than exploiting wildlife, why not use the money and creativity being invested here to better train people? After all, humans like a good reward-based dopamine hit as much as the next animal. What’s the smallest amount of money that would encourage someone to dispose of their cigarette waste? That’s the start-up I’d rather see. Or better yet, pay people living wages to act as care takers for our communal spaces. Some problems don’t need a grand solution, they simply need our humanity.

Literature cited

  1. Ridpath MG, Thearle RJP, McCowan D, and Jones, F.J.S. 1960. Experiments on the value of stupefying and lethal substances in the control of harmful birds. Annals of Applied Biology 49: 77-101

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Filed under Corvid health, Crow behavior, crow diet, Crows and humans, In the news, Science

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October 20, 2021 · 9:54 pm

How smoke affects wildlife

It’s September 8th, 2020 when I step out my front door in Eastern Washington into a landscape that looks like the aftermath of a Martian dust storm. The video I am recording captures my bizarre, sepia-colored surroundings as I try to put words to the experience of having your world an entirely different color than it was the day before. Like any inconsequential casualty in a disaster movie, my usual sense of self-preservation has been abandoned in favor of standing in harm’s way, mouth agape with my phone outstretched to the sky. After a minute, I realize my error and head back inside where I, and millions of other people on the West Coast spent the next several weeks hiding from air that can kill you.

That year, wildfires would go on to burn a total of 10.2 million acres on the west coast, cause $19.8 billion dollars in damage and directly kill at least 37 people. Over the last 30 years, fire severity and duration have increased and it’s impossible not to notice. Decades of wrongheaded fire management coupled with increasingly hotter, drier summers have meant that the 2-3% of wildfire starts we fail to suppress burn under the very worst conditions, pumping the air full of the kind of fine particulates that are irritating at best and deadly at worst. Unsurprisingly, the public health community has been swift to respond, with hundreds of studies examining the outcomes of smoke inhalation on humans. But while I and many other people were able to escape indoors during the worst of it, crows were unanimously stuck in a sepia haze…breathing. One has to ask; how do they cope? How does any wild animal cope?

Among those wondering was Olivia Sanderfoot, an imminent PhD graduate from the University of Washington. While there, she spent the majority of her time asking different questions about how smoke impacts wildlife, especially birds. In pursing her own research, Dr. Sanderfoot made a striking realization: despite the fact that nearly every birder, biologist and person were all wondering about how animals deals with smoke, there were only a few research studies. So with the help of her graduate lab, including myself, she resolved to collect and synthesize what papers were available into a comprehensive review. Published just this week, I am eager to share what we found.

As of the time our article was accepted, there have been only 41 English language studies examining the impacts of smoke on wildlife. Of those, less than half (44%) examined in situ (free ranging) animals dealing with real smoke events. Most were controlled studies where animals were intentionally exposed to smoke to learn about its impacts on their health or behavior. We found that from insects to sugar gliders a variety of different animals had been studied, but only 7 papers focused on birds (and sadly none on crows). Birds are of particular interest not only because, crows, but also because birds have a more efficient respiratory system than any other vertebrate. While this usually offers many advantages, it also quite literally makes them the canary in the coal mine—their high sensitivity to air quality acting as an important bioindicator in addition to the obvious consequences to welfare and conservation.

Although we had hoped to find clear answers to exactly how wildfire smoke impacts animal health, we only found 10 papers that addressed health outcomes specifically, and only 4 that ultimately looked at survival. Still, there are many more papers examining this question either in domestic animals, or animals models that are used as proxies for humans. When taken together with those findings, it’s clear that smoke isn’t good for animals, resulting in anything from carbon monoxide poisoning, to respiratory tissue damage, higher blood acid levels, stunted growth, compromised immune systems, and even death. Beyond direct health effects, exposure to smoke can may also reduce reproductive success. For example, researchers monitored the red-knobbed hornbill, a sort of toucan-like bird native to Indonesia, suggested that smoke might have contributed to a decline in the bird’s nesting success.

Smoke can induce behavioral responses among animals as well. Animals may become confused, agitated, vocal, lethargic, or quiet. For example, Bornean orangutans rest more during and after smoke events, Bornean white-bearded gibbons sing less, and sugar gliders extend the duration of torpor. Meanwhile pinecone lizards flick their tongues more, Psammodromus lizards start running, and many species of bats rouse from their torpor. Some birds are harder to detect like bald eagles, bushtits, killdeer, osprey and marsh wrens, while cedar waxwings, western tanagers, red breasted nuthatches, and yellow warblers actually become easier to detect as particulate matter (smoke) increases.

When taken together, it’s clear that wild animals are sensitive to smoke, and that smoke can have dramatic impacts on their health and behavior. But perhaps the most important finding of our review is that the predictability of these consequences for any future wildfire event remains almost completely out of reach. Because the thing about smoke is that it’s not all created equal. Smoke can have vastly different consequences to health depending on what’s burning (just think of the carcinogenic difference between cannabis and cigarette smoke), not to mention the impact that concentration and duration of exposure can have. And unfortunately, most existing studies haven’t undertaken the kinds of robust studies of air quality that are needed for this kind of future predictive power. Still, knowing this, and having a framework of existing knowledge and methodology, means that future studies are poised to finally start building the foundation we need for sophisticated, predictive modeling.

Until then, we can expect that smoke events like the kind we experienced in 2020 will continue to haunt our changing planet, and while some humans can safely nest alongside their air purifiers, many more, and all our wildlife, are at the mercy of an airscape they cannot retreat from. For now, this is our reality but it need not get inhospitably worse. Just has humans are capable of bullheaded, catastrophic damage, we are also capable of a profound capacity to change, improve and heal. It’s time to take bold, industry/system level steps towards changing our climate future, if only we can find the will to do so.

Read the whole paper here: https://iopscience.iop.org/article/10.1088/1748-9326/ac30f6/pdf

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Filed under Birding, Climate change, Conservation, Corvid health, New Research, Wildlife

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October 2, 2020 · 12:01 am

Bill overhang in corvids

I hardly notice it when I’m in the field because the bird is either too far or too fussy for me to examine the finer details of its beak, but looking at pictures like this I can’t help but notice that little extra bit of bill that sweeps over this raven’s bottom mandible like an awning. It leaves me wondering, what is this overhang for? A why is it more noticeable on some individuals than others?

When we think of birds with curved upper mandibles we are most primed to think of raptors, which have the most conspicuously curved overbite of any group of birds. This shape give them the tearing power they need to breakdown and consume their prey. But upon closer inspection we can see that actually most birds, even some hummingbirds, have a slight* overbite known as maxillary overhang. Among corvids, common ravens have one of the most noticeable overhangs, though they can be quite visible in crows as well. Unlike raptors though, for most other birds this overbite has less to do with food consumption and more to do with hygiene.1

While they can be good at hiding it under those sleek feathers, wild birds are constantly contending with a suite of exterior parasites like gnats, feather lice, and mites. The presence of these parasites, and the speed at which they can cause real harm if left unchecked, is part of the reason birds dedicate so much time and energy into preening. To remove and kill these pinhead sized parasites, birds carefully comb through their feathers, individually plucking up offenders with their bill tip. Even a small (1-2mm) overhang has been show to provide a significant advantage to birds by providing a backdrop against which the lower mandible can pin and damage parasites. Without such an overhang, parasite loads can be as much as 4x higher. By contrast, the overhang doesn’t seem to play any measurable role in foraging success or efficiency.1

Given the largely carrion based diet of common ravens, it’s possible their more visible overhang provides some advantage when it comes to digging into a carcass. Since it hasn’t been tested, however, I can only guess that if some feeding advantage does exist here, it’s slight. This is supported by looking at other carrion specialized corvids, which don’t seem to show a particular bias in longer overhangs relative to their omnivorous or seed eating corvid cousins, and the fact that even within common ravens overhang length is variable.

This common raven doesn’t have a particularly big overhang

To an extent, the longer the overhang the more effective it can be. As anyone who has tried to maintain naturally long nails can attest though, long keratin based appendages are prone to damage and breakage. Bill tips are no different, which explains why there can be so much variation between and within species. The overhang is playing an evolutionary balancing act to arrive at the length that is the most effective and the least vulnerable to damage. That means that not only will some species have shorter or longer overhangs, but individuals within species may, at any point, exhibit more or less obvious tips as due to recent damage. As a result of this variability, I don’t recommend looking to the level of bill overhang as a diagnostic tool for identifying ravens. While it’s certainly useful for crushing bugs, you can’t bank on it being useful for winning that next round of #CrowOrNo.

Two crows with slight variations in bill overhang.

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* Some corvids have more than simply a slight overbite. Unusually long or misshapen bill tips can be the result of a viral infection called avian keratin disorder. Check here to learn more about AKD in crows.

Literature cited

  1. Clayton DH, Moyer BR, Bush SE, Jones TG, Gardiner DW, Rhodes BB, and Goller F. 2005. Adaptive significance of avain beak morphology for ectoparasite control. Proc. R. Soc. B 272: 811-817

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Filed under Corvid health, Crow curiosities, Diversity, Ravens

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August 26, 2019 · 8:43 am

Dumpster diving is giving crows higher cholesterol—but does it matter?

Whether it’s from actively watching crows, or simply just existing in a city, we’ve all seen it: the overflowing garbage bin with fat-stained wrappers littered at its base, and the crows snapping up each bit of leftover junk like spilled money.  Cheetos, cheeseburgers, fries, nuggets, chips, or pizza, they will devour basically anything fatty and salty with absolute glee.  This behavior is so canonically crow that it’s stapled into our contemporary imagery of these birds.  Take this 12ft statue called “Crow with Fries” by artist Peter Reiquam.

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Photo c/o salishsea

I’d wager that most people don’t think about this behavior beyond simply finding it amusing or annoying, but I suspect that if you describe yourself as crow lover, naturalist, or bird watcher, you’ve been struck with the same thought as me: “This stuff is called junk food for a reason—it’s bad for you.  What’s it doing to these birds?”

Given that anthropogenic foods can account for as much as 65% of an urban crow’s diet, it seems essential to understand what a diet derived from regularly feasting at McDonalds might do to an animal with 0.7% the body mass of a typical human.1  Unfortunately, we could do little more than shrug and speculate as to its effects.  The data for a more informed understanding just didn’t exist.  That is, until today.

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A new study published in The Condor by Dr. Andrea Townsend et al. examines the relationship between urbanization, junk food, and the body conditions of crows.2  To conduct this study, her team blood sampled 140 wild crow nestlings along an urban to rural gradient.  They found that plasma blood cholesterol levels increased in correlation with the amount of impervious surface, which is a typical way we measure urbanization.  This finding suggests that crows in the city have more access to high cholesterol foods and they make haste in gobbling it up.

Correlation is not causation, however, so to confirm this, they ran an additional supplementation study where they provided 10 rural crow parents with 3 McDonalds cheeseburgers 5-6 days a week, and then looked at how their nestling’s blood cholesterol levels compared with unsupplemented nestlings from the same area. They found that eating cheeseburgers most days of the week had a demonstrable effect on the subject’s cholesterol levels.  While this finding may not be raising any eyebrows, the actual logistics of carrying out a study that required buying hundreds of cheeseburgers each week, and sometimes in one order, certainly did.  In one of their more memorable attempts, Hannah Staab called to place an order for 125 pickle-less cheeseburgers, a request to which McD’s staff replied, “Sure, we’ll get right on that.”  When she arrived several hours later to pick them up, however, they hadn’t made any, having been convinced that the call was a prank.  The peculiarities of urban fieldwork never falter.

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So far, these findings tell us little more than what most people could have probably intuited, but they were crucial to laying the foundation for the real clogged heart of this study: Whether any of this is actually a bad thing.  In the final piece, they examined the body condition, and 2-3 year survival of the 140 nestlings sampled along the urban to rural gradient.  They found that cholesterol levels had no detectable effect on survival and were actually correlated with higher indices of body condition (meaning mass adjusted for size), a feature that is sometimes tied to higher reproductive success and survival. In other words, there might actually be a scenario where regularly pigging out on McDonalds doesn’t kill you and is maybe kinda helpful?

Needless to say, this caught everyone off guard, including Dr. Townsend, who told me, “I was surprised that we didn’t detect any negative health effects. I was thinking—based on the human literature—that high-cholesterol birds would have lower survival rates, but we didn’t see any effect of cholesterol on survival.”

So what gives? Is the universe really just this unfair?  While we can’t rule out that the answer is simply, “Yes,” the authors speculated that it’s possible a longer study would bear out health consequences that take more than a few years to accrue. There’s also something to be said for the fact that body condition has complex and not always agreed upon relationship with fitness and survival.3 While some studies show pudgy birds have more resources to produce more offspring and keep on ticking, others find inconsistent support. Alternatively, crows may just not live long enough to see their lifestyle catch up to them.  Future long-term studies will be necessary to fully understand whether crows have truly found a loophole in the junk-food problem. For now however, I’m happy to wish my favorite dumpster divers well, though I’ll hold off placing my own orders.

Literature cited

  1. Marzluff JM, McGowen KJ, Roarke D. and Knight RL. 2001. Causes and consequences of expanding American crow populations in Avian ecology and conservation in an urbanizing world (J.M. Marzluff, R. Bowmanm and R Donelly, eds).  Kluwer academic Press, norwell, Ma.
  2. Townsend AK, Staab HA, and Barker CM. 2019. Urbanization and elevated cholesterol in American Crows. The Condor page 1-20
  3. Milenkaya O, Catlin DH, Legge S, and Walters JR. 2015. Body Condition Indices Predict Reproductive Success but Not Survival in a Sedentary, Tropical Bird. Plos One https://doi.org/10.1371/journal.pone.0136582

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Filed under Corvid health, Crow behavior, crow diet, Crows and humans, New Research

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January 9, 2017 · 1:31 am

Crow curiosities: Why their feet don’t freeze

With a peanut visible in my gloved hand, we square off.  The crow eyes me from its snow covered perch, weary of such gifts offered by strangers.  Above us a raven castes a disinterested look, croaks, and flies away.  I toss the nut into an empty parking space and the crow descends to quickly collect its prize.  The space between us must be widened before it will comfortably eat however, so I decide to leave the crow to its snack and return to my car.

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Scrunching my feet in my shoes, I’m relieved for the excuse to retreat.  It’s about 10˚F outside and despite the wool socks and insulated boots between my skin and the snow I can tell that my feet are numb from the cold.  Even stashed in my pocket, my gloved hands are having trouble articulating to their full range.  How is it that my extremities lose function even with so much coddling and yet the crows can continue using their bare toes to steady and manipulate food in such cold weather?

To be clear, birds are endothermic, or warm blooded, just like mammals.  In fact, on average, birds run a little hotter than mammals.  And their feet, like ours, requires warm blood both to function and to prevent the tissues from outright freezing and causing cell death.  Yet despite these needs birds can comfortably walk, stand, or even sleep on ice.

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Glassy ice makes cold footing!

To do so, they can take advantage of two important adaptations.   The first is that the size of the arteries carrying blood into the legs and feet is exceedingly small.  Given this high surface to volume ratio, the blood has already lost most of its heat by the time it reaches the feat, and can’t lose much more to the outside world.  The second is that they employ what’s called a counter current heat exchange system.  Essentially, warm blood traveling away from the core and towards the feet via the arteries comes into close contact with colder blood traveling away from the feet and towards the core via the veins. At this point of contact, heat from arterial blood is transferred to blood traveling in the veins. This heat exchange system allows for the tissues in the feet receive just enough heat to prevent cell death, and can reduce heat loss by up to 90%1.

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A crow wades out across a frozen Drumheller Fountain in search of scraps

As an additional strategy, you’ll see them protecting their exposed legs under their body feathers, as if they’re incubating them.  This is the same reason you often see winter birds standing on one leg.  By switching back and forth, birds can minimize overall heat loss by reducing the exposure to only a single leg.

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A crow covers its feet while it waits (hopes) for a handout

So while I need special clothing to keep my extremities at a similar temperature range to my core, the physiology of most birds is adapted to simply allowing extremities to exist at near ambient temperatures with no tissue damage.  In other words, rather than crows’ feet not getting cold, their feet simply are cold.  That said, frostbite is still a possibility even in birds, particularly for: nonnative species, birds in wire cages, birds with metal legbands, and birds in unseasonably cold conditions.  If frost bite occurs, early treatment at a rehab facility can prevent long term damage2.

Still, the idea that cold-adapted birds can keep their hearts beating away at around 105˚F even while their feet are exposed to freezing temperatures is marvel of adaptation and thermoregulation!

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Literature cited:

  1. Elphick C, Dunning JB Jr., Sibley DA (eds).  (2001) The Sibley guide to bird life and behavior.  New York: Alfred A. Knopf
  2. Wellehan JFX. (2003). Frostbite in birds: Pathophysiology and treatment.  Compendium 25: 776-781

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Filed under Corvid health, Crow behavior, Crow curiosities

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January 5, 2017 · 5:54 pm

Saving the rarest crow

It can be hard to imagine crows as anything but ubiquitous.  During winter across the country, dusk marks the time where some cities see their skies turn black with thousands, even hundreds of thousands of American crows converging to roost.  These crows have taken nearly all that people have thrown at them: deforestation, mass waste, and the urban sprawl that simplifies previously complex ecosystems, and uses it to their advantage.  Not all species of crow have thrived in the Anthropocene, however.

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Thousands of gather accumulate in the skies above UW’s Bothell campus in the winter

Far from being icons of the ultimate adapters some species of crow represent some of the most endangered animals in the world.  Among those, the ‘Alalā or Hawaiian crow, is arguably one of the rarest birds on earth. Once locally abundant in the forests and woodlands of Hawaii’s Big Island, their decline began in the 1890’s following persecution by coffee and fruit farmers1.  Back in September, 2015 there remained only 114, all living  exclusively in captivity giving them the unenviable title of ‘extinct in the wild’.  How can one species thrive with such zeal while another holds on by a thread?

Island species are generally more specialized and therefore more sensitive to human induced changes.  In fact proportionally, islands host a higher number of endangered or extinct species than continental areas2.  In Hawaii alone, 77 different species of endemic birds have gone extinct since the arrival of the Polynesians 2,000 years ago4, all largely for similar reasons: habitat destruction and invasive species.

Unlike their generalist, continental counterparts, the ‘Alalā is more specialized to feed on understory fruits and nuts and in fact were key seed distributors for many of Hawaii’s native plants.  Island living also fostered a similar behavior seen in only one other species of crow: tool use.  Like the New Caledonian crow, the ‘Alalā is a dexterous tool user, though the two species are only distantly related.  Scientists believe this example of convergent evolution is fostered by aspects typical of islands, namely low predation and low competition for embedded food5.

Unfortunately, limited distributions and higher specialization also meant their population was more fragile than that of continental crows.  Logging, agricultural development, loss of native pollinators, and alterations by non-native ungulates challenged both food acquisition and breeding habitat.  Introduced diseases such as avian pox, malaria and the Toxoplasma gondii parasite carried by cats further weakened an already ailing population6,7. Invasive predators including rats, mongoose and cats consumed eggs, nestlings and fledglings.  Finally, humans continued their tradition of persecution, particularly feral pig hunters who would shoot the birds before they could alarm call and scare off their prey2.

Together, these threats set into motion a decline in population we failed to recover despite some increases in research and management starting in the 1970’s.  The last known wild egg was laid in 1996, and the last wild pair was seen in 20022,3.  Some people did recognize the urgency of their decline prior to 2002, however, and a captive breeding population was started successfully rearing over 90 birds8.  Although such a small number of breeders may raise red flags with respect to inbreeding and genetic depression, this is rarely as big of an issue as is commonly perceived.  Unfortunately, light management and depredation by the also endangered Hawaiian hawk (‘io), decimated the released population and reintroduction efforts were halted in 1999 until a larger captive population and better management strategy could be devised.

Since that time, the ‘Alalā Restoration Project (collaboration between the State of Hawaii, the U.S. Fish and Wildlife Service, and San Diego Zoo Global) has spearheaded captive breeding programs on Maui and the Big Island culminating in a population of over 100 birds.  An important part of these captive breeding programs is the use of puppets, which help prevent habituation to humans9.  In addition, intensive management operations have taken place to ready their prospective home at the Pu‘u Maka‘ala Natural Area Reserve including the removal of invasive/feral animals, erecting exclosure fencing, and constructing a sort of half-way house to help ease the birds into life in the wild.  These efforts have not been without setbacks, however.  Back in June, 2015 two miles of protective fencing was cut down by vandals, though their motivations remain unknown.

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A human dressed as an ‘Alala feeds captive reared nestlings. Photo c/o San Diego Zoo Global

Finally, after so much work, the end of 2016 marked the first time researchers and managers agreed the elements were in place for a reintroduction effort.  On December 14th, five male birds were released onto the reserve, marking the first time the ‘Alalā set claw into the wild since 2002.  Sadly, within weeks all but two had died. Two were killed by the native Hawaiian hawk or ‘lo, and the third was killed by “natural circumstances” which, I’m guessing, is related to a heavy storm that occurred shortly after their release.  As a protective measure, the remaining two were recaptured until the results from the necropsies are obtained.

While clearly disheartening, early hiccups in a release effort like this are not unusual and conservationists and biologists are not losing hope that success is still possible.  Part of ensuring such success, however, is undoubtedly public support particularly with respect to maintaining the strength of the Endangered Species Act and support of the ‘Alalā Restoration Project.  The perception that all crows are alike or that generous populations of American crows means protections for other corvus species is unwarranted or redundant will be a disaster for these rare birds.  So make your voice heard when funding for conversations efforts come under fire, and share your passion for endangered corvus species with friends and family.  The fate of the world’s rarest crow quite literally depends on it.

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Two newly released ‘Alalas peer around their new surrounding in the Pu’u Maka’ala Natural Area Reserve.  Photo c/o the San Diego Zoo Global 

Literature cited

  1. https://www.fws.gov/pacificislands/fauna/alala.html
  2. Faike, E. 2006. Wild voices in captivity: the date of the ‘Alala. Birding 38: 64-67.
  3. Banko, P. C.; Burgett, J.; Conry, P. J.; David, R.; Derrickson, S.; Fitzpatrick, J.;
  4. National Research Council (US) Committee on Scientific Issues in the Endangered Species Act. Science and the Endangered Species Act. Washington (DC): National Academies Press (US); 1995. 2, Species Extinctions. Available from: https://www.ncbi.nlm.nih.gov/books/NBK232371/
  5. Rutz C, Klump BC, Komarczyk L, Leighton R, Kramer J, Wischnewski S, Sugasawa S, Morrissey MB, James R, St Clair JJH, Switzer RA, and Masuda BM. (2016).

    Discovery of species-wide tool use in the Hawaiian crow.  Nature 537: 403-407 doi:10.1038/nature19103

  6. Maxfield, B. 1998. Wild ‘Alala population suffers major setback. ‘Elepaio 58: 51.
  7. Liebermann, A.; Nelson, J. T.; Simmons, P.; Unger, K.; Vitousek, P. M. 2003. Draft revised recovery plan for the Alala (Corvus Hawaiiensis. US Fish and Wildlife Service, Portland, OR, USA.
  8. Lieberman, A. C., Kuehler, C. M. 2009. Captive propagation. In: Pratt, T. K.; Atkinson, C. T.; Banko, P. C.; Jacobi, J. D.; Woodworth, B. L. (ed.), Conservation Biology of Hawaiian Forest Birds: Implications for Island Avifauna, pp. 448-469. Yale University Press, New Haven.
  9. Valutis LL, and Marzluff JM. (1999).  The appropriateness of puppet-rearing birds for reintroduction.  Conservation Biology 13: 584-591

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October 26, 2016 · 7:03 pm

New research on the cause of the AKD outbreak

Since the nineties, Avian Keratin Disorder has been an increasingly common disorder among Alaskan and PNW crows, chickadees (~17% of northwest crows1, ~6% of black-capped chickadees2) and a handful of other species, that causes gross deformities of the beak such as elongation, curvature or crossing.  I’ve written previously about the details of this disease before, but at that time there was little progress in determining the underlying source of the outbreak.  While AKD can be caused by a variety of things, at the scale it’s being observed now scientists questioned if there was a more consistent underlying factor.  Since AKD can cause discomfort or even death (primarily through the inability to feed or preen) understanding what might be the source of this outbreak has clear management and conservation implications.

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An AKD-afflicted American crow in Seattle, WA.

Among the initial suspects were environmental contaminants such as heavy metals, organic pesticides, and toxic environmental pollutants like PCBs, PCDDs, and PCDFs.   Blood work done on afflicted Northwestern crows, however, showed no significant difference in the 30 blood elements tested compared to unaffected adults or juveniles3.  Fortunately, new research may finally be shedding light on what’s going on.

Disease can be an easy thing to rule out if you know what you’re looking for, but new to science pathogens can evade traditional diagnostic techniques.  To account for this, a team of USGS and university scientists conducted a sequencing study comparing pooled RNA of healthy and AKD positive chickadees, crows and nuthatches in attempt to identify a candidate pathogen2.  Their work appears to have paid off, revealing evidence for a new picornavirus (a family of viruses previously known to science) they are calling poecivirus.  Whereas 100% of AKD-affected birds (23 subjects) tested positive only 22% of the 9 control individuals did.

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Alaskan black-capped chickadee with severe AKD. Photo c/o Martin Renner

Given these small sample sizes, it’s too early to throw our hands up in complete relief of having identified the cause of the AKD outbreak, especially since there’s still much to be done in understanding the potential relationship of this new virus to the environment.  Nevertheless, these findings offer some insight and hope that scientists are on the right track.  With more dedicated work we may soon have a much better understanding of this novel pathogen, its link to AKD, and management options moving forward.

Literature cited

1.  Van Hemert C, & Handel CM. 2010.  Beak deformities in Northwestern crows: Evidence of a multispecies epizootic.  The Auk 127: 746-751.  doi: http://dx.doi.org/10.1525/auk.2010.10132

2. Zylberberg M, Van Hemert C, Dumbacher JP, Handel CM, Tihan T, and DeRisi JL. 2016. Novel picornhttps://wordpress.com/post/corvidresearch.wordpress.com/3363avirus associated with Avian Keratin Disorder in Alaskan birds.  mBio 7 doi: 10.7589/2015-10-287

3. Van Hemert C, Handel C. 2016.  Elements in whole blood of Northwestern crows (Corvus caurinus) in Alaska USA: No evidence for an association with beak deformities.   Journal of Wildlife Diseases 52:713-718 doi: http://dx.doi.org/10.7589/2015-10-287

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June 9, 2016 · 2:57 am

5 reasons to leave baby crows alone 

Those blue eyes, that awkward gate, their seemingly constant precariousness, they’re all calling to you to intervene. Here are 5 reasons second guessing that instinct might be in the bird’s best interest.

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1) The vast majority don’t need your help. It’s totally normal for baby crows to be on the ground and flightless as long as they’re covered with feathers and appear otherwise alert and mobile. Even nestling crows are usually on the ground on purpose. Not because they are ready, but because their parents have intentionally rejected them for one reason or another. They will die and that’s ok. Part of coexisting with wildlife is giving them the agency to be wild. The story is different of course for species where the survival of individuals may mean the difference between population survival and extinction, especially because these situation are almost always driven by human activity.

2) It’s hard to tell when they’re stressed.  Recently, I saw a video on Facebook of a Steller’s jay fledgling in the care of a very well intentioned person.  She was giving it gentle strokes with her fingertips, each touch resulting in the young bird turning its head towards its back and opening its mouth.  The comment thread filled with ooo’s and awww’s and general comments of encouragement or gratitude for her actions.  For me it was like watching an alien attempt to care for a human child, the child recoiling and screaming while its caretakers congratulated themselves on how kind they were being.  Having handled baby corvids before, I know what that kind of posturing means, it means “I’m scared and stressed.”  To an untrained eye though, it may not look much different than the kind of gaping that means ‘feed me.’  Being stressed to death is a reality for young, or even adult animals, so any handling best be done by experts whenever possible.

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3) It’s illegal to rehab crows without a license. You can provide temporary care until you can get them to a licensed facility, but do not attempt to rehab them on your own.  Mistakes like the one I just described are a prime example of why the law seeks to protect animals by ensuring they are only raised or rehabilitated by experts.  For more information on how to handle them until you can get them to a facility visit my previous post.

4) Imprinted crows do not survive well in the wild.  Even if baby crows are receptive to being treated like a pet, doing so is both a legal violation and I would argue a violation of their right to be a wild animal with a healthy fear of people.  Of all my daydreams, at the top of the list is having a wild but imprinted crow that follows me around.  I even have a name picked out.  This fantasy of mine will forever remain just that, however, because it’s too dangerous to allow a crow to become that comfortable with people.  All it would take is one cranky neighbor with a pellet gun and it would be over.  Not to mention being imprinted on people, instead of crows, denies them access to skills and relationships with other crows that will help them survive into adulthood. 

5) It may do more harm than good.  The conventional wisdom suggests “well, worse case scenario is I try and rehab this baby crow and it dies, which it would have done anyway so really, nothing’s been lost.”  The more we study death in social animals the more we are beginning to realize there may be a cost to prematurely removing ailing or dead animals from their groupmates.  Being able to interact with their dead may serve an important role for social animals, and denying them this opportunity may have serious implications in their ability to process that death.  So be thoughtful about how slim the chance of survival is.  It might be that the kindest, most responsible action is no action at all.

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February 8, 2016 · 5:32 pm

Crows with broken beaks

It hurts to look at.  The physical pain incurred at the time of the injury, the likely chronic pain on the path to recovery, the dubious chance of survival, it all makes me reach for my mouth in horror when I see this bird.  To me, the idea of living on in spite of such a grotesque injury seems impossible.   Yet here this bird is, surviving, reminding me of what life is capable of.

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So now that I had my moment of sadness and awe, let’s get to what everyone wonders when they see a bird like this: Will a crow’s beak grow back if it’s broken and if not, can it survive?

Cracks or complete fractures like this can result from a number of things, though the list could be longer since these accidents are so rarely observed firsthand.  Perhaps it was traumatic run in with a window, or perhaps the upper or lower bill got trapped against a fulcrum point and an opposing surface.

As far as the prognosis is concerned, I asked birds experts, wildlife rehabilitators and veterinarians and the answer was always an equivocal ‘maybe’.  Maybe it would heal back to something resembling normal and maybe it would remain stunted. Maybe it would survive and maybe it wouldn’t.  To fully understand the reasoning behind this ambiguity you need to understand how a bird’s beak is actually formed.

Like mammals, birds have two jaws bones that form the upper and lower mandibles.  These bones are surrounded by the nerves and blood vessels that support the beak’s functionality and growth. Protecting these layers is the outer lightweight layer of keratin called the rhamphotheca.  Like our fingernails, this layer is always growing and being replaced.

Depending on where the fracture occurs, the rhamphotheca can grow back enough to abolish the injury.  Unfortunately though, there’s not much room to work with before you hit bone, and the bone cannot be regrown.  In these cases the rhampotheca may heal over the exposed bone, but it may not grow back to full size since the template for its shape (the bone) has been stunted.  Even if it does grow back, it may not do so correctly, leading to twisty shapes.

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A crow skull.  You can see that the jaws bones are almost the full length of a crow’s beak.  The black outer layer, the rhampotheca, adds only a little (think mm) extra length so there’s not much that can be removed from the tip of the bill without hitting bone.

So what’s the prognosis?  Well again, that depends.  Even if the bill does not grow back correctly, or at all, some crows can learn to compensate.  Fortunately, being a generalist helps their chances considerably.  Although some foods may now be out of reach, many crows lean how to scoop, poke, and jab their way to a full stomach everyday. The same cannot be said for many species of bird whose beaks are the cornerstone for consuming a specialized diet.

So while it’s fair to be heartbroken at such an injury, it’s not cause for hopelessness. Many crows will learn to compensate, and go on to remind us of the beautiful stubbornness of life.

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