Photo copyright Jolyon Troscianko

Regarding Tool Manufacture and New Caledonian Crows

I tend to leave incidental posts, responses to Tumblr posts, and Tumblr replies to the Tumblr incarnation of this blog, trying to keep this official Coyot.es space more for original content and longer posts.  However, this reply was lengthy enough and contained enough original material beyond the initial reply that I thought it would be good to post it here.

This comment is a reply to my correction of the source page for the incorrect NowYouKno “fact” on Tumblr.

I appreciate you pointing out this distinction, though manufacture versus use is sort of a continuum, depending on how we are defining “manufacture”.  It is true that New Caledonian crows are amazing tool makers (something I give lectures about on a nearly annual basis when I talk about animal culture), but more than three species make tools.  Chimpanzees, of course, are tool makers, along with documentation of manufacture in orangutans, mandrills, and Asian elephants.  This is leaving out animals that develop tools or can be taught to develop tools in captivity (ex. bonobos, hyacinth macaws, and a Goffin’s cockatoo, just to name a few).  Also depending on how complex the manufacture, gorillas have been observed breaking off large sticks for stabilization, woodpecker finches have to break off cactus spines to use them (and more recently they are modifying non-native blackberry spines), and bottle-nosed dolphins have to select and break sponges off their substrate to use them.  I still assert that we will probably find a lot more tool use and manufacture in the wild, the more chances we get to observe different species in the wild.  There are certainly many anecdotal and incidental observations of many more species creating and using tools.  However, what you have to keep in mind is that if an animal gets along fine without making and using tools, then there’s not point in them doing so.  Tool manufacture and modification, while really cool to us, isn’t always necessary for other animals.  In chimpanzees and humans, for example, tool use is integral in how we forage and exist in the world, but for other species tool manufacture and use may only be needed on occasion, when a situation calls for it.

In the case of New Caledonian crows, they, like woodpecker finches, live in places that lack woodpeckers.  This is significant because it leaves open the niche that specializes in locating, removing, and eating wood boring insects.  Rather than spending the time to evolve physical adaptations to do this (like woodpeckers have) these two species use tools to the same ends.  Arguably, there is a distinction between woodpecker finches (which are actually most likely in the tanager family, despite the common name) and New Caledonian crows when it comes to the cognitive department.

What happens when nature takes a bird, already a part of a large-brained, cognitively complex genus of birds (Corvus) and puts it on an island that has a goldmine of a niche to fill?  You get the incredible New Caledonian crow (Corvus moneduloides).


(Photo copyright Jolyon Troscianko)

Drs. Russell Gray and Gavin Hunt observed these birds in the wild manufacturing and using tools.  The earliest documented account of tool us in NC crows was by an explorer who reported the use of anvil sites to crack open nuts and snails in 1882.  In 1909 Le Goupils observed NC crows probing a dead log with a stick-tool (reported in 1928) and Orenstein gave a more detailed report on crow tool-use in 1972, but it was Hunt (his first study published in 1996) and Gray who brought attention to these incredible corvids and who still do work on them today.  In 2000, birds were taken from New Caledonia and sent to England to be studied by Alex Kacelnik‘s Behavioral Ecology Research Group (BERG) at the University of Oxford.  Two of these birds were Betty and Abel.  Betty blew the minds of the world when she spontaneously bent a metal wire into a hook to retrieve food after Abel made off with the hooked tool.

Part of the reason the NC crows were brought into captivity by Kacelnik was to see if the tool behaviors were innate or due to complex cognition and problem solving, or even if they were cultural as Gray and Hunt suggested.  The BERG found that young NC crows, with no training or example, had a proclivity for tearing materials and probing holes with other objects.

So if the birds could manufacture and use tools completely on their own, what makes them more noteworthy than woodpecker finches or other animals that innately use tools?  What makes them rival and often exceed chimps in the cognitive department?  Tradition, the understanding of the functional properties of their tools, innovative use of tools, and cumulative tool evolution all combine to make NC crows stars in the world of animal cognition.

Gray and Hunt found that different tool types were being used by NC crows in different regions of New Caledonia.  These tool types were not reproduced by Kacelnik’s captive crows, which lends more support to those tools’ forms being based on a tradition, or culture, rather than just a genetic ability to make them (after all, humans babble as a precursor to language).  NC crows also understand the functional properties of the tools they use and make.  They use a range of materials and techniques for making tools, demonstrating that it’s the crow that decides on the tool, not the material.  Understanding of the functional properties of their tool was also demonstrated by Betty bending the wire, and again in further experiments.  One experiment even showed that the crows could determine the rigidity of tools that would be appropriate for a task.  Finally, NC crows show cumulative tool evolution, something we humans still clung to as unique to us.  Cumulative tool evolution is the ability to take a tool and modify it to a different or better function and build on previous technology.  The tools that were created by precisely snipping and tearing Pandanus spp. tree leaves (the form of which were not replicated by Kacelnik’s captive birds) showed strong evidence of enhancement over time.  Hunt and Gray found and compared tool types and their functions from all over the island, including historical records of negatives left in leaves up to four years old.  Their findings suggest that the Pandanus tools have had significant improvement on their shape and functionIf this doesn’t blow your mind, I don’t know what will!!

Researchers have since found evidence of cumulative tool evolution in chimpanzees as well.  And thus, the battle for most cognitively complex non-human tool user rages on between chimpanzees and NC crows.  In recent years, the ability to use tools to get tools (or meta-tool use) has been a focus of attention, with several studies demonstrating that NC crows can figure out what tool they need for a task, and use other tools to get the appropriate tool (here’s a video).  There have also been studies into the brains of New Caledonian crows, among other cognitive work that shows that these birds are truly complex animals that blur the line between human and non-human intelligence and understanding of the world around them.  Click here for The University of Auckland’s page on NC Crow research still run by Gray and Hunt, and here for a list of their publications which go well beyond what I’ve related to you here.  Both researchers at The University of Auckland and The University of Oxford are continuing work on these birds, so you should keep an eye out for their continued publications and findings.

I’m a huge fan of NC crows, if it wasn’t apparent.  One of my most treasured possessions is a genuine Pandanus tool made by a New Caledonian crow.  I even had one of Hunt and Gray’s papers signed (how big of a nerd can I be?), but that was sadly destroyed in a flood.  It is a life goal to make it to New Caledonia and observe these birds in the wild.  Thank you Pamela Turner for giving me an excuse to blather about NC crows and I hope all of you who read this now appreciate them as much as I do!

Finally! A movie that’s fair to Corvids!

Finally!  A film (Maleficent) that portrays a raven accurately and fairly (though the CG flight animation could use some work).  Not to give too much away about the film, but this is the first movie where I’ve seen a raven portrayed as a “good guy”.  In fact, the raven, Diaval (renamed from Diablo in the animated movie), is the most morally consistent character in the film.

I can’t say more without giving away too many spoilers, but if you like corvids, especially the crows, see this movie.  I saw it on a whim and I was pleasantly surprised, not just by Diaval, but by the film as a whole.

This film gets The Corvid Blog’s endorsement!

(GIF from Cinemablend.)

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Australian Crows – Guest Post by Matthew Brown!

This is a special guest post by fellow corvid researcher Matthew Brown. Matt is a PhD candidate at Griffith University’s Environmental Futures Research Institute in Brisbane, Queensland and studies Torresian crows (Corvus orru).  I asked him to write about Australian crows and his research for this blog and he was kind enough to do so.  Enjoy!!
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For the past three years I have been studying one of the most common birds on the Australian continent, the Torresian crow. Crows have become extremely common in Australia over the past two decades, nowhere moreso than in the Queensland capital city of Brisbane. A subtropical city of two million people, Brisbane provides enough lawns and rubbish to support enormous populations of crows and other scavengers. Such is the abundance of crows and their interaction with humans so common that the Queensland Government Department of Environment and Heritage Protection has a “Living with Crows” page on its website.

A Torresian crow caught at Griffith University’s Nathan Campus in Brisbane. The crow, 40cm long and approximately 750g, was banded for identification and released.

Five species of corvid exist in Australia, including three sedentary species: the Torresian crow (Corvus orru), Australian raven (C. coronoides) and Forest raven (C. tasmanicus), and two smaller nomadic species, the Little crow (C. bennetti) and Little raven (C. mellori). Only the Torresian crow exists in Brisbane.

Despite having the names crows and ravens, these five species are a monophyletic clade, which means they all come from the same ancestor. So an Australian raven is more closely related to the Torresian crow than to, say the common raven (C. corax) from the Northern Hemisphere. The exception to this being that the Torresian crow also exists in Papua New Guinea, as a separate subspecies.

The five species are best identified by their geographic location, but also their calls. Each species have very distinct, though extremely complex and variable, calls which can’t really be mistaken for each other (with the possible exception of the Australian raven and little raven).

The current theory about how, after crossing over from PNG, the corvids split into five species across Australia is explained in-depth in the late Ian Rowley’s paper “Why five species?

Torresian crows, while territorial, spend the night in permanent communal roosts scattered throughout Brisbane. These vary widely in size, and can contain anything from a few dozen to 200 birds. The roosts are often also shared with rainbow lorikeets and ibis.

All Australian corvids hatch with blue eyes as chicks, then change to the juvenile brown, then the adolescent hazel before finally becoming the adult white with a blue inner ring at about 2 years old. The process is the same for all 5 species, though the exact time of each stage varies. This is the easiest method to tell the juveniles apart from the adults. Early European scientists used to consider them separate species (the brown-eyed crow and the white-eyed crow) before they finally figured it out.

Juvenile crows stay with their parents for approximately six months, though this appears to be highly variable. After leaving, they join what are known as ‘juvenile gangs’, which often congregate around shopping centres or parks, areas with a large amount of human scraps. One of the largest of these gangs permanently live in the South Bank Parklands. The Queensland Government estimates that crows have a 95% infant mortality rate, though those surviving to adulthood (2 years old) can live up to 30 years.

One of the largest permanent juvenile gang sites is the popular South Bank Parklands, likely due to the abundance of human food available.

Compared to the extensive research conducted on New Caledonian crows, American crows, common ravens etc, very little is known about the Torresian crow. Because of this, my studies are focussing predominantly on replicating Northern Hemisphere studies on this species. These include:

In addition, I have already undertaken a study comparing neophobia (a fear of novel objects) in Torresian crows with other non-corvid corvines including butcherbirds, currawongs and Australian magpies. The extreme neophobia present in crows has made working with wild birds very difficult, requiring an extensive familiarisation process. My study of the Torresian crow’s vocalisation system also revealed not only extraordinary diversity in calls, but suggested the presence of a nested hierarchy similar to that deemed present in American crows by researchers in the United States. Professor John Marzluff described crows as likely possessing a basic form of language, and on the surface at least it appears that Torresian crows can match or even surpass their American cousins in this regard.

Torresian crows have already shown some of the remarkable qualities expressed in their overseas cousins. The invasion of North-Eastern Australia by cane toads has been disastrous for all native fauna, except the crow. Crows in Eastern Queensland were first recorded to be flipping toads onto their backs, allowing them to peck at their bellies and avoid the poisonous glands on their backs. Very soon after, much sooner than one would expect, crows as far as Darwin were performing the same behaviour. How the information spread so far so quickly is unknown. Crows have also been reported unzipping school bags and stealing food from children’s lunchboxes, and working as a team to move large carrion off of rural roads, while one acts as a sentry warning of oncoming traffic.

My own observations have confirmed that Torresian crows can recognise friendly or unfriendly human faces and act accordingly, though are extremely wary of all humans that pay them any attention. The infamous crow funerals appear to be present in Brisbane as well, though crows being hit by a car or electrocuted is quite rare.

Crows are a joy to study anywhere in the world, but in Australia there is a level of mystery that makes it all the more rewarding. So little is known about the crow that everything is a new discovery, and provides an intriguing comparison with better-known species from the Northern Hemisphere and in New Caledonia.

Two crows, one banded, participating in the familiarisation process of an experiment at Griffith University’s Nathan Campus.

 

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Winter Crow Invasion!

Do you have a metric tonne of crows flooding into your neighborhood/town/city each night?  Do you feel like the crow population is getting out of control?  Are you worried that Alfred Hitchcock’s “The Birds” is about to be a reality?  Do not fear!  What you are experiencing is perfectly normal winter behavior for crows!  In this post we will discuss ROOSTS!

Thousands of crows coming in to roost for the night.

What is a roost?

A roost is a place where birds sleep.  In the context of crows, a roost usually consists of many birds gathering in one location, at dusk, to sleep for the night.  In the winter American crows (Corvus brachyrhynchos) in particular gather in the hundreds to thousands to even millions, in some exceptional cases, each evening.  It’s quite a sight to see and might be a bit disturbing for anyone unfamiliar with this winter behavior!  However, the behavior is just that, a winter one and is therefore temporary.  Crows form massive roosts from November (at the earliest) to about March, when they go back to their home territories to start the nest-building and breeding process.

Why do they gather in such large roosts?

We don’t know for sure, but it’s something American crows have done forever.   One hypothesis as to why they gather like this in winter, is for safety.  One of the main predators for American crows is the great-horned owl.  With longer nights in the winter, having a large group to sleep with after dark might help your chances of not being attacked by an owl.  Having so many other birds means there’s a greater chance it will be a different individual that gets attacked, and also means you have more birds that can detect a predator and send up the alarm to everyone else.  Other hypotheses involve possible information exchange, about foraging sites, but it hasn’t been studied in crows, and many crows just return to their home territories during the day.  It could be that visiting crows (that may have migrated from the north, for the winter) might find out about good foraging sites, but it’s probably not a large contributing factor to roosting behavior.  Finally, roost sites may be conveniently close to good foraging sites, and therefore a good place to sleep.

Crows coming in over an industrial area.

Why do they gather in my town/city?  And not the woods?

I’m sure there are roosts in the woods that people don’t know about, but the biggest conflict with roosts and people are in towns and cities.  Ever parked your car under some trees filled with thousands of birds?  Ever walked under thousands of birds?  Neither the car, nor yourself, likely come out without a fair deal of poop covering you.  Roosts are also quite noisy before the birds all settle down to sleep.  And even then, if they get disturbed in the night, they all sound the alarm, which is quite loud coming from thousands of already-noisy birds!

There are no studies saying exactly why the roosts tend to be in towns, but one hypothesis is that the crows like the light.  Crows see about as well as us humans at night, and the added light might help them spot and evade the dreaded great-horned owl a bit easier.  Great-horned owls are also less abundant in towns.  Urban areas are slightly warmer than rural areas as well, which is an added bonus in the cold winter.  Thirdly, most urban areas prohibit the discharge of firearms, which protects crows from being shot.  Urban areas may also provide better actual sleeping sites, such as taller or specific kinds of trees.

In some cases a roost may have been near a town before the town was even built up, and then the town itself became suitable for roosting (due to the reasons I just gave).  In the case of one roost the Crow Research Group studies, the roost has been documented in the same rough location for over 100 years.  It used to be three miles south of the town, but is now in the middle of downtown, and it likely moved due to the reasons I stated above.

Crows gathered in a group of tall trees.

Doesn’t a roost of so many birds indicate that crows are overpopulated?

No, and there are a couple of reasons why.  Remember that I said crows have been doing this forever?  Well, even if there were only 10 crows in a 100-mile radius, they would come together in the winter to roost.  Additionally, some crows migrate.  In the winter here in New York we tend to get migrant birds down from Canada that join our roosts and communal foraging sites.  So the number of crows in a roost is NOT indicative of the population in a particular area.  The roost contains birds from many miles around and possible migrants.  In the case of roosts further north, they may see fewer crows, as many of theirs have taken off to warmer climes for the winter.

There’s a roost in my town or nearby, what should I do??

Go watch them an enjoy yourself!  Seeing such large aggregations of birds is thrilling and you get to see all sorts of great flights, behaviors, and hear a variety of sounds.  It’s quite comical watching crows vie for space on a branch in a particularly over-loaded tree.

I say bring revenue into the town by having a crow festival in the winter!  Do crow-themed foods, crafts, attractions, competitions, etc.!  Make an eco-tourism site and bring in the money as well as educate people about crows and how wonderful they are!

Is there current research on roosts?

Glad you asked!  The Crow Research Group is trying to get some funding via Microryza (crowd-sourcing) to do some movement and roost research!  My colleague, Ben Eisenkop, is interested in how these large roosts affect nitrogen cycling in local environments (since crow poop is chock full of nitrogen).  If you would like to contribute, please click the following link!

What are the patterns and effects of American crow movements?

CROWIAMA_advert

Reddit IAmA: Crow Research Group!!

On Monday, January 27th, 2014, myself and three other crow researchers will be doing an IAmA day on Reddit!!  For those of you who don’t know what an “IAmA” is, it’s basically a day-long question and answer session with an individual or a group of interest.  Get those crow questions you have always wanted to ask answered by experts!!

Here is a link to where the Crow Research Group IAmA will be taking place: http://www.reddit.com/r/iama

Please share this advertisement and pass it on to any of your friends and family that you think will be interested.

 

 

Crows and Shiny Objects

I got this question from csmithstudio on Tumblr:

Hi Jenn! A friend told me about your blog and I’m delighted and grateful to you for taking the time to post this! I am an artist focusing almost entirely on birds and I would like to do a painting of crows including the treasures they commonly collect. I’ve tried to research what they might be attracted to but so far have only found golf balls and angry golfers! Do they stash their hoard in a nest or somewhere else? Thank you! Christina

I’m super glad you asked me this!  I’ve been meaning to post about this topic.  The reason you can’t find anything is because crows don’t collect shiny things.  This is an extremely common myth, but it’s just that, a myth.  (And I’ve seen way too many “official” websites state this myth like it’s fact, so don’t feel bad for believing it!)  The thing is, stories about crows collecting shiny things are anecdotal, and not observed by people who watch crows constantly and study them.

There’s a couple of reasons why people might think crows like and collect shiny objects and continue to pass along the myth.  First, young crows are very curious about everything.  They play with all sorts of objects they find in nature, and chances are if something is glinting they may me more likely to explore that object (just like how you might notice something glinting in the grass and investigate it), than something that blends in to the background.  As I talked about in a previous post, juvenile crows are the same size and, to the untrained eye, look just like adult crows, therefore people may be attributing a juvenile play behavior to all age groups, accidentally.  Are they particularly attracted to shiny objects, or obsessed with them?  Highly unlikely, they may just be more likely to find them because they are easier to see/attract attention easier (welcome to why advertisers use shiny and bright things on other humans to attract their attention).  Honestly, adult crows are more likely to be terrified of brightly colored or shiny objects unless heavily associated with food on multiple occasions.

Second, a lot of observations about crows playing with shiny objects come from people who have had pet crows.  A hand-raised crow is going to have a lot of exposure to human objects, and will therefore play with those objects.  They may be attracted to what their “parents” (the humans) are attracted to, and therefore be more interested in rings, watches, silverware, etc. for the reason that they are of high value to their “family” not because they are shiny objects.

Third, it is likely that the shiny or bright objects simply remind the crows of food, or the crows are investigating them for potential food opportunities.  The going theory for why crows and ravens are so attracted to golf balls, as Christina mentioned in her note, is that they look an awful lot like delicious eggs.  I have personally watched crows play with and steal golf balls off a golf course (which was hilarious).  However, they lose interest pretty fast after, presumably, realizing the objects aren’t food (though I swear some of the crows just had a blast chasing those golf balls around).

There are a number of reasons why crows may be attracted to shiny or bright objects and trinkets, but no more so than you or I or most animals would be attracted to them.  In other words, their interest in shiny objects does not appear to be inordinate.

So, do crows hoard the objects they find?  No.

Crows don’t hoard anything.  If a crow takes off with your keys, it was likely that the bird wasn’t done exploring them for any food opportunities and took off with them to finish it’s inquiry in safety (and probably dropped them somewhere when it realized it had no use for the keys).  Crows, and other corvids, do cache items, which means that they store them for later (see my post about Nutcrackers for the most incredible cachers), but wild crows only store food items (I say “wild” because captive birds may cache non-food items, which would be expressing an instinctual behavior, using non-typical items found in the captive habitat).  Furthermore, they don’t cache all of the food items in the same location (larder).  Crows (and most corvids) are scatter cachers and leave bits of food all over the place within their territory (I once watched a crow pull half a ham sandwich out of the branches of a spruce tree…I still have NO idea where he was keeping it in there, but it was pretty hilarious to watch).  So there is no secret hoard full of shiny objects to find in a crow territory.

What about the nests?  Well, crows don’t use nests for anything but raising babies.  The nests are built just before egg-laying at the beginning of the breeding season, are lined with soft grass and moss, and are immediately abandoned once all the kids fledge.  Crows don’t store objects in a nest or sleep in a nest (unless you are a baby or the bird on incubation duty during the breeding season).  Although crows have been reported to use wire hangers and other urban metal materials to build the structure of their nests, this is more likely due to the utility and availability of these objects as construction material, not because they are shiny.  You may wonder if crows might put shiny objects in the nest to attract attention from potential mates, but crows have selected mates far before nest building begins.  If you find a crow nest in the wild, you won’t find wondrous treasures, you are likely to find a pile of sticks, grass, and poop….and sometimes a sleeping raccoon (true story).

So in conclusion, Christina, I would love to see you possibly illustrate caching behaviors of food, since those are the most valued treasures for crows.  In urban/suburban environments I’ve seen them cache everything from seeds and dead animals/insects, to ham sandwiches, pizza, and french fries.  It might be more fun (and accurate) for you to explore the wide and variable diets of these birds.  Feel free to contact me for more details if you are interested! :)

You have also given me the chance to review a game a friend bought for me recently, Crows by Valley Games, Inc.  I brought this game to a lab meeting and as a crow research group we played.  While thoroughly not impressed by the premise of attracting crows with shiny objects and trinkets, it was still quite fun!  We highly recommend it with the caveat that you replace “shiny objects and trinkets” with “peanuts and road kill.”  They certainly hit the mark with the trash tiles though.

A board game that is fun, but propagates the inaccurate myth that crows are inordinately attracted to and collect shiny objects.

 

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I Am Not A Baby Crow!

Alright, it’s time for me to say something about baby crows as I’m greatly saddened when I see photos being passed around as “cute baby crow”.

Here’s the first offender that is not, I repeat NOT a baby crow:

NOT a baby crow, not even close.

The bird photographed above is a baby buff-banded rail (Gallirallus philippensis), and isn’t even remotely related to a corvid.

Another offender:

Also NOT a baby crow!

This bird is a corn crake (Crex crex) chick (thank you Sheri, Melissa Penta, Tammy Campbell and Pete).  Another bird nowhere near related to a corvid.

I can tell these aren’t baby crows because I know what baby crows look like and have extensive experience with them, but how about for other people?  Well, your first big hint is the fluffiness.  The fluff, or down, that you see is indicative of a precocial bird chick.  There are two kinds of hatching development types that occur in birds; precocial and altricial.  Precocial chicks are those that can walk, have down, open eyes, and are ready to eat on their own within hours of hatching.  Some of the most well known examples are chickens, geese, turkeys, quails, pheasants, waders, and ducks (among others).  Crows (in fact all corvids) have altricial young which are naked little jelly-bean monsters with closed eyes upon hatching and are reliant on their parents/family for weeks to months to nearly a year (depending on the species).  When altricial birds emerge (fledge) from the nest they are (or very nearly are) the size of their parents!

So here is a real baby crow:

A young baby crow, only a few days old. Photo by Melanie Piazza at Wild Care.

They start off rather not-cute, but they get cute fast, in my opinion.

A real baby crow!  This bird is about 24 days old.

As you can see, from the photo of a baby crow that is only a few days old to one that is 24 days old, they grow rapidly.  A 24-day-old crow is still in the nest (the one photographed above fell out, and I put him back in!) and can’t fly.  The 24-day-old is still growing its flight feathers and tail and will not start to fly until it’s about 35 days old or older.  Notice the older baby has his nasal bristles, a distinct crow beak (even at only a few days old), highly scaled legs, solid (not downy) body feathers, and a pinkish gape (“lip” structure at the base of the mouth/bill).  Baby crows also have blue eyes, which I adore:

Blue eyes of a baby crow. In some species (Australia for example) some baby crows start with dark brown eyes and they become blue as they grow older. In the case of the American crow (photographed) the blue eyes slowly turn to a dark brown.  Note the pink gape at the base of the bill.

Blue eyes on a baby common raven.  Also note the pink gape and mouth.

When people start to actually see baby crows on the ground in the spring and early summer, foraging with their families, they are the size of their parents.  A big tell that the crow you are seeing is a baby is that it will have a bright red/pink mouth.  As crows grow up their mouths turn all black.  When they are babies, their mouths are bright red!  Here is a photo of a baby crow, who is fully flighted and has fledged from the nest, begging for food from a family member:

A baby/fledgling crow (pink mouth) begs from a family member.

Baby crows are not fuzzy fluffballs, but they are still rather adorable.  The best way to experience their cuteness is to watch their silly behavior, something I’ve been doing for years for my research.  Their behavior and antics are a lot of fun.

Here’s a video I took this past summer of three siblings dutifully destroying local foliage in an effort to learn about the world around them (and having fun!).

 

Final note: If you do happen to ever find a baby crow, please refer to my colleague Dr. Kevin McGowan’s website on what to do!  Note that crows are federally protected in the United States and are not legal to own as pets.

Mariana Crow

I’m taking part in an art project called “Losing Altitude“.  It’s a collaborative art book project that will feature over 50 artists from around the world who work in a wide range of media. The book will feature threatened and endangered species of birds from all around the world!  The project is headed and organized by Arras Wiedorn who was kind enough to invite me and my husband to the project.  Naturally, I chose a corvid to illustrate, the Mariana crow (I’m particularly invested as I know several of the researchers who work on them!).  Here is the piece, with information about this critically endangered species below.

Species: Corvus kubaryi

Common Name: Mariana Crow, Aga (in Chamorro), previously known as the Guam Crow.

Distribution: Endemic to and only found on the islands of Guam and Rota in the Mariana Islands.

Habitat: Mature and second-growth forest and coastal strand vegetation. Birds tend to forage in the canopy, understory, and occasionally the forest floor.

Diet: Omnivorous, feeding on fruits, seeds, invertebrates, small vertebrates, and opportunistically on eggs.

Status: Critically endangered! The Mariana crow was down to seven individuals on Guam in 1999. Individuals were introduced to Guam from Rota, increasing the population to 16 individuals. However, in 2008 only two males remained. The last sighting of a Mariana crow on Guam was in 2011, and the species is likely extinct from the island. The decline on Guam is mostly attributed to the introduction, right after World War II, of the brown tree snake (Boiga irregularis), a highly invasive species that has devastated native vertebrate populations on Guam, among other issues. On the island of Rota the population has also been in decline. In 1982 the population was estimated to be just over 1,300 and in 2008 the population was down to an estimated 70-400 mature individuals. The brown tree snake is not yet established on Rota with only one dead specimen found in a Rota harbor. The decline on Rota is likely due to other invasive species (monitors, feral cats, rats), habitat destruction, disease, and direct persecution.

Conservation Efforts: Efforts to keep sections of remaining forests on Guam snake free, for further reintroduction attempts, have been established. On Rota, aggressive conservation plans are in progress. Predation control experimentation, public education, forest protection, captive breeding, refined population survey methodology, and research are all a part of efforts to prevent the Mariana crow from going extinct (predicted to happen within 75 years).

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This piece depicts an adult Mariana crow picking out the soft parts of a hermit crab it has just opened. A juvenile, still with slightly blue eyes, light-colored bill, and feather sheaths on the growing tail feathers, watches the adult. The border depicts brown tree snakes in the upper corners, representing the main reason for extinction on Guam. In the snakes’ coils are crow eggs to represent predation. Below the snakes are transverse cross-sectional representations of a bread fruit, one of the fruits the crows consume. Below that are oceanic geckos and next to them at the bottom are leaf-rolling crickets, other typical foods for the Mariana crow.

I want to thank Sarah Faegre and Renee Ha of the Rota Avian Behavioral Ecology Program for sharing photographs and information with me. They are fantastic researchers and people. Please check out their website and follow what is happening to the Mariana crow!

corvus tristis with watermark

Where’s Jenn?

I apologize for the lack of posts, however it’s not due to a lack of doing corvid-ee things!  Beyond the constant working on my dissertation (about American crows), the past few weeks have been busy with a bit of travel, particularly to natural history museums, and now to the 50th Annual Animal Behavior Society Conference (which starts tomorrow).

I’ve got a lot to talk about when I’m back home, but for now I’m going to leave you with some photos from my visit to the American Museum of Natural History‘s collections.  Natural history museums have wonderful public displays, but the bulk of their materials are in their collections, not on display.  The AMNH has six floors of bird specimens alone, and I was able to examine Corvus species I’ve never seen in life, heck, they had all of them, so I learned a LOT about the fine physical features of birds I’ve only seen in photographs and illustrations.  There is a huge difference between a photograph and a bird in the hand…including me squealing and babbling incoherently in excitement.

Sitting in front of a collections cabinet at the AMNH, looking through skeletals of various Corvus species.  (Shirt is from Raven’s Brew Coffee.)

Perhaps the most exciting specimens for me. These are Grey Crows (Corvus tristis), a species found all over New Guinea. We know very, very little about them, but we do know that their coloration throughout their life history is just, well, bizarre. It was an unbelievable treat to get to see and handle these specimens!