A Manitoba winter, especially this one, without the friendly, buzzy, “chick-a-dee-dee” calls of our neighbourhood black-capped chickadees (Poecile atricapillus) would be that much harder to endure. The prolonged cold spells, incredible wind chills, and many blizzards made these birds and their cheery presence even more welcome at our backyard feeders. But while we were entertained watching from behind the window of a warm house, these tiny, 14-gram balls of fluff (just a little heavier than a AAA battery) were flitting about outside in -35°C temperatures amidst blowing snow. How do they do it?!
There certainly is a long list of challenges for a small bird to survive a northern winter. Low temperatures are the obvious one. Small animals have a higher surface to volume ratio than larger animals, meaning they expose relatively more body surface to the elements per gram of weight – small animals lose heat more quickly than large animals. Chickadees have a normal body temperature of about 40°C, meaning that on a day of -40°C (not unusual over much of its northern distribution in Manitoba) there is an 80°C gradient through 2 cm of feathers from outside air to skin. And winter days are short, meaning fewer daylight hours to gather enough food to maintain that body temperature.
Chickadees have several adaptations to fend off winter’s worst. Feathers, as some of us know from our down-filled parkas, are extraordinarily good insulation. But all adult birds have feathers, and most migrate south for winter. So what else do chickadees do?
Well, our chickadees are likely to be extra buff in winter! Relatives of Manitoban chickadees have been shown to have chest muscles up to 30% larger in winter than in summer. Chickadees spend little time in continuous flight in their daily activities, so why would these flight muscles get bigger in winter? These larger chest muscles are vital sources of heat production. Chickadees use bursts of shivering to create heat and these muscles do that work, as well as power flight.
Chickadees are also big energy-savers. Like some of us that turn the house thermostat down at night to save energy while we are asleep, chickadees also turn down their thermostats at night using what is called nocturnal hypothermia. Chickadees reduce their body temperatures by as much as 10°C and this can provide a 50% energy savings overnight! One study showed that even reducing body temperature by only 8°C can increase the time to when a chickadee needs to eat to re-fuel by well over an hour. This extra time could spell the difference between overnight survival and death.
Finding a warm roosting spot to stay overnight is also important. Hunkering down in a tree cavity provides a microclimate where heat loss is minimized. Tree cavities can provide an effective temperature difference almost 15°C higher than at an exposed site. This can mean an additional 35% energy saving and greatly increase fasting endurance, the time between required feedings, by seven hours! On very cold days, chickadees spend almost ¾ of their time at their roosting site. This explains why our backyard feeders, just when you might think they would be busiest, seem mysteriously chickadee-free on very cold, windy days.
But when chickadees wake up in the morning and do need to feed, what are they eating and where are they finding it? In summer, chickadees eat mostly insects but in winter, when it is more difficult to find overwintering insect eggs, larvae, and adults, about half of their diet is seeds and berries. Chickadees are opportunistic and readily visit feeders. But they are not reliant on feeders to get through the winter, in part because they store food!
Chickadees are famous for taking seeds and berries and caching them in a hiding spot, and rarely in the same place. This reduces the risk of losing access to food in the future. On a tough winter day there is a store of available food. And having many, separate places protects this important food source; if all the seeds are hidden at the same spot, perhaps a squirrel, mouse, or other bird might discover them and have a feast, or poor weather might destroy the cache. Having hundreds of individual, safer hiding spots does create a different problem, however. The chickadee needs to remember where to find them all again. Research has shown that chickadees are up to the task, able to recall the locations of hundreds, even thousands, of stored seeds – for up to a month!
Chickadees that rely on stored food have a relatively enlarged part of the brain, the hippocampus, that is important for spatial memory. Although some research initially suggested that the hippocampus increases in size in the fall, potentially to accommodate these memories, more recent work is inconclusive. However, it is no less spectacular that chickadees in harsher northern climates, that would be expected to have a heavier reliance on stored seeds, have a larger hippocampus with more and larger neurons than do chickadees in southern populations. This does suggest that natural selection in a harsher climate has favoured individuals with heritable traits that increase spatial memory.
The next time you see a black-capped chickadee flitting about on a frigid day, perhaps consider all that is going on inside that tiny ball of fluff to get it through the winter. Chickadees do make even our coldest winters cheerier, but there is a lot of serious work going on under that black cap.
If you can’t find a chickadee outside, you can see them in the Boreal Forest and Parklands galleries in the Manitoba Museum. And you can learn about winter adaptations of many kinds of animals throughout the galleries.
[For further, more detailed summaries of chickadee winter biology, see: Pravasudov, V.V. et al. (2015) Environmental influences on spatial memory and the hippocampus in food-caching chickadees. Comparative Cognition & Behavior Reviews, 10, 25–43.; Olsen, J.R. (2009) Metabolic performance and distribution in black-capped (Poecile atricapillus) and Carolina chickadees (P. carolinensis). PhD Dissertation, The Ohio State University.]
The Museum opened our newly renovated Prairie Gallery just last spring with spectacular new exhibits on the intriguing and engaging natural and human history of southern Manitoba. The addition of ground squirrels and their burrows, a riverbank bison bone bed, a homesteader stone house, an old school room, and hundreds of new specimens and artifacts, along with life-sized animations, prairie soundscapes, and feature videos provide exciting immersive experiences.
But some things from the old ‘Grasslands Gallery’ didn’t need changing, only a facelift. The pronghorn diorama at the gallery’s entrance remains as awesome and as valuable an educational tool as it did when it opened over 50 years ago in the summer of 1970, when it caught the eye of our first official visitors, Prince Philip and Queen Elizabeth:
The Prince asked a good question – pronghorn were frequently seen in the province prior to 1880, but are now only rare visitors wandering from North Dakota or perhaps Saskatchewan. But this is just one of hundreds of good questions that the diorama can illicit and help answer.
The diorama was designed, its backdrop painted, and installation overseen by renowned Manitoba artist Clarence Tillenius. He began planning in August 1968 and completed it, along with the bison diorama (much longer in production, from 1963), in June of 1970. As has remained the tradition for our dioramas to ensure authenticity, Tillenius visited the site that is portrayed, driving with other Museum personnel north of the U.S. border “to a point south of Waskada from where I [Tillenius] painted a study of the west end of the Turtle Mountains [sic] which appear in the background landscape.” (From a June 12 1970 letter to Dr. F.A.L. Matheson, then-president of the Museum.)
A rough plan for the diorama as envisaged by Tillenius. The basic size and shape was maintained, but only two actual pronghorn, a male and female, were in the final exhibit with a herd painted into the backdrop.
The pronghorn diorama effectively introduces the new Prairies Gallery much the way it introduced the original Grasslands Gallery, except for the new vibrant panels and its reinterpretation in a modern context. But it still shows the southwestern part of the Manitoba as it was before colonization, providing an opportunity to think about the transformation of our prairies over the last 250 years. The pronghorn diorama might be the closest some of our visitors ever get to experiencing original prairie in three dimensions. They can wonder at its expanse, its wildlife, and ponder its future. And it will do so for the next 50 years, or more we hope, perhaps inspiring the next generation of nature-conscious Manitobans to save our last vestiges of wild grasslands and their inhabitants.
Enduring – according to the dictionary – means having a validity that does not change or diminish. The pronghorn diorama, and the Museum’s many other signature life-size dioramas (bison, polar bear, caribou, moose, wolf den, elk, bat cave, snake den, Delta Marsh, Winnipeg 1919, and Nonsuch) are prime examples of enduring, undiminished wonder, exploration, and inspiration.
Come see for yourself!
Celebrating Canada’s first 150 years does not usually involve thinking about the environment or biodiversity, and certainly Confederation is a human history event. But human actions have an impact on our environment and the creation of Canada was no exception. Our latest exhibit, Legacies of Confederation: A New Look at Manitoba History, offers an opportunity to explore those impacts, those legacies, from a natural history perspective. Given the massive changes to Manitoba’s environment since 1867 (and 1870 when we became Canada’s fifth province), it is easy to focus on the negative effects; indeed, grasslands and many of their component parts have become rare or have even disappeared. But becoming a nation can also bring substantial resources to bear on mitigating those impacts through policy, funding, social conscience and national pride.
Outlaw #5 is a magnificent bison head that hung in the Winnipeg City Council Chambers in 1912 and is now hanging for all to see in the Legacies exhibit. This seems the beginning of a depressing story rather than a positive one, and in some ways it is; this bull bison is an unlucky representative of one of the last significant herds of plains bison (Bison bison bison) in North America at the turn of the 20th century. But it also represents the beginning of an incredibly successful conservation story – bringing bison back from the brink of extinction. I have introduced this specimen before, but this amazing mount has so many incredible stories to tell that I can’t resist an encore presentation.
The big bull once roamed the grassy hills of Montana as part of the Pablo-Allard herd. Much of this herd, perhaps all, was made up of what were originally Canadian bison (although nationalities are irrelevant to the animals!). The initial herd was the offspring of a few calves brought from near the Alberta/Montana border in the early 1870s. Others arrived through a rather circuitous route, likely from calves caught near Prince Albert, Saskatchewan by Charles Alloway (brother of William Alloway, founder of the Winnipeg Foundation) and James McKay (Manitoban politician, Treaty negotiator) also in the early 1870s and kept at Deer Lodge in Winnipeg. These went to Stony Mountain Penitentiary under the care of Samuel Bedson (warden), becoming a herd of perhaps 100 over about ten years. Most of these were sold to Charles “Buffalo” Jones in the late 1880s and brought to Kansas before eventually becoming part of the Pablo-Allard herd in Montana through sale. Here the herd grew to several hundred, but Pablo (Allard had passed away) was notified by the U.S. government that his lands could no longer be used for bison. He offered them for sale to Washington but negotiations bogged down.
Canada came to the rescue. Alexander Ayotte, a Manitoban working for Canadian Immigration in Montana at that time, heard that the bison were up for sale and he notified Canadian officials. A deal was struck and Canada bought the herd in 1907. There is some suggestion that purchasing the Pablo-Allard herd was as much an opportunity for the government in Ottawa to poke a stick in the eye of the United States as it was to preserve a species, but there is little doubt that the individuals directly involved with the transfer, as well as the general public, were genuinely committed to conservation. Regardless, the end result was that over 700 bison were brought by train to Alberta, the nucleus of essentially all plains bison we see in Canada today and the basis of a conservation success story.
So where does Outlaw #5 fit in? As you might imagine, getting wild bison onto a train to Canada is no easy feat and some of them, the “outlaws”, refused to board. These remaining animals had no home and they were shot. At least thirteen outlaw bulls found their way to Winnipeg and into the skilled hands of Manitoba’s Official Taxidermist (yes, we had one of those), E. W. Darbey. He mounted these in his shop at 233 Main Street and they were auctioned in the fall of 1911.
As I noted in my original blog, I used the horn patterns from the archival photographs and those on the Museum specimen to identify it as #5, marked by the yellow arrow in the image above, a task that was none-too-easy or even certain. To prepare the specimen for exhibit, it required careful conservation to repair damage on the skin, nose, and ears, as well as stabilization of the backboard before we could hang it. Carolyn Sirett, our conservator, had to remove the backboard from the mount and the first thing she saw was that the mount was numbered. She immediately called me to say I should come up to her lab. To my relief (and some satisfaction), in large black writing was “No. 5”! Carolyn repaired the mount, and removed an incredible amount of dirt from the fur to make the specimen look much as it must have over 100 years ago.
Although I have not yet determined how Outlaw #5 came to be in the possession of The Hingston Smith Arms Co. Ltd. (they are not listed as purchasers at the auction), documents generously shared by the City of Winnipeg Archives show that in January of 1912 that company offered to hang the head in the City Council Chambers. This was in order for it to “be seen to advantage” and determine if Council would be willing to purchase it. After all, it was “the finest specimen of Buffalo Bull Head” and “the best one of the lot of out-law bulls of the Pablo herd.” It seems most of the Council agreed, as only one month later they voted 10 to 7 to buy the head for $750 – equivalent to over $18,000 today! And they engraved the description much as boasted by the company onto the plate that adorns the backboard:
So as Outlaw #5 stares haughtily down on visitors today, he is both a symbol of our capacity to destroy and an incredibly important symbol of our potential, as Manitobans and Canadians, to be better stewards of our nation’s spectacular natural world.
Confederation has fostered the diversity of perspectives that will help us through environmental challenges and that will work towards solutions over the next 150 years. Our exhibit might not provide the kind of birthday celebration we are likely to see on July 1st, but instead encourages a more sobering and reflective look at Confederation from a Manitoba viewpoint – how it happened, where we’ve been, and where we’d like to go. The incredible artifacts and specimens we have had the privilege to exhibit and interpret provide signposts to guide that thoughtful reflection.
Legacies of Confederation: A New Look at Manitoba History is open until January 7, 2018 and is free with admission to the Museum galleries.
September 1st of 2014 marked the grim anniversary of the death of the last passenger pigeon on Earth. It’s extinction is probably the only one for which an exact hour of demise is recorded; the last individual was a captive bird, named Martha, that expired at 2pm local time at the Cincinatti Zoo. The disappearance of this species is almost impossible to comprehend, as it was once the commonest bird in North America, perhaps even the world, with population estimates of between 3 and 5 billion – yes, that’s billion – in the mid-1800s.
But the capacity of humans to destroy knows no bounds. The awe-inspiring flocks that were described as darkening the sky from horizon to horizon, and the massive breeding colonies that numbered in the tens of millions were slaughtered by market hunters and shamefully wasted by hungry locals alike. Unfettered exploitation along with changes in environment due to deforestation resulted in the shocking disappearance of passenger pigeons from the wild by about 1900.
Although Manitoba never hosted massive colonies, large flocks provided food for First Nations peoples and hungry homesteaders, and were important enough to frontier life to merit frequent mention in local newspapers as “wild pigeon” or merely “pigeons.” Passenger pigeons bred in small groups in the south of the province and were seen as far north as Hudson Bay.
In contrast to their abundance in the 19th century, there are relatively few specimens of passenger pigeons in natural history museums and even fewer of those that have information on when and where they were collected. This is in part because systematic museum and research collecting in North America was still relatively new, and because passenger pigeons were so common; who carefully collects crows or starlings today? The Manitoba Museum has five taxidermied specimens of passenger pigeon. The fifth was obtained just recently via a generous donation from the Delta Wildlife Foundation, a female that is featured in a new acquistitions case, The Passenger Pigeon: 100 Years of Mourning, that is on exhibit from November 1, 2014 to April 12, 2015.
Until recently, all of the Museum’s passenger pigeons were of unknown locality – we weren’t even certain that our birds were actually from Manitoba! Record-keeping was not always thorough in the 1930s when some of them came into the possession of the original Manitoba Museum, and the others were in private collections where their exact histories have been lost. However, while examining some photographs of the exhibits in the old Civic Auditorium from the 1930s, I noticed that some were of the bird cases. One of these had three of our pigeon specimens on display! And another photo showed that one mount had very specific data on its label just below it tacked to the back of the case:
Did the Museum still have this particular specimen? Comparing our present collection with the photographs, I was able to determine that one of the five birds we have is an exact match for the Winnipegosis specimen that had been on display in the 1930s. This is especially important because detailed information on this bird was published by G.E. Atkinson in 1904, a taxidermist and naturalist from Portage la Prairie. He prepared this specimen and noted its date of collection as April 10th of 1898 – the last specimen ever collected in Canada!
So the specimen has come full circle in its history with The Manitoba Museum. It was first on display in the mid-1930s in the Civic Auditorium, was in our collections storage for 40 or more years, and is now on exhibit again 80 years later at Rupert and Main. It remains, after all that time, still able to perform the unfortunate, but important function as a flag-bearer representing all extinct species and as a warning of where careless attitudes to our environment can lead us.
Aldo Leopold, the famous Wisconsin environmentalist, said in memory of the passenger pigeon in 1947:
“There will always be pigeons in books and in museums, but these are effigies and images, dead to all hardships and to all delights. Book-pigeons cannot dive out of a cloud to make the deer run for cover, nor clap their wings in thunderous applause of mast-laden woods. They know no urge of seasons; they feel no kiss of sun, no lash of wind and weather; they live forever by not living at all.”
And indeed, the Museum’s passenger pigeons will not, unfortunately, repopulate our skies. But they will always be here, for that is the value of museum collections – archives of natural history and silent witness to changes in our world. Our collections provide opportunity to study, marvel, contemplate, and learn. And although there are no more passenger pigeons in the wild, they can still be found in museums. I invite you to The Manitoba Museum to see the last passenger pigeon ever collected in Canada, along with two others, and to reflect on their fate as well as our own place in the world.
The Passenger Pigeon: 100 Years of Mourning is free with admission and is on exhibit from November 1, 2014 to April 12, 2015.
If you have any further information on these specimens or others, please contact the Museum.
Hallowe’en is upon us and all the traditional ghosts, goblins, witches and bats are making their annual appearance. The Museum just hosted a very successful members’ night that included trick-or-treating for kids. But a recent (unfortunate) offer of a real bat to our Zoology collections has me thinking that we need to re-evaluate the inclusion of bats as a Hallowe’en symbol – they just don’t belong at this time of year!
Manitoba has six species of bats. Half of these are “cave bats” as shown in the image above. Over the winter, most of the individuals of these species likely stay inside the province or in nearby provinces or states by hibernating in caves. Big brown bats occasionally find shelter in buildings. The caves are cool, but do not freeze and offer stable temperatures and humidity that are good for hibernation.
The other three species are the “tree bats” that are illustrated in the image above; the red bat is a particularly attractive species (although for many, “attractive bat” is likely considered an oxymoron!). The “tree bats” escape our winters by migrating out of the province in late summer and fall, likely to the southern United States, and return each spring.
But just as with us when we wait too long to put on the snow tires, bats sometimes get caught by cold weather. That is what happened to an unfortunate silver-haired bat just last week (October 23) that was found lying dead on a Winnipeg sidewalk. Despite attempts at warming the little guy, it did not revive and was offered to be a part of the research collection here at the Museum. Such donations provide the raw materials to help understand these (and other) little-known animals. The Museum is grateful for these donations, and in some ways, gives the organism a second “life” where it can be studied and be used for exhibits and other educational purposes.
The silver-haired bat is likely the commonest tree bat in Manitoba (and North America), but despite this we know surprisingly little about it. They are long-distance migrants, probably spending the winter in the southern U.S. and returning to Manitoba certainly by May – we have found them clinging to the Museum on occasion as they are on their way to northern forests. These are spectacular trips for animals that weight the equivalent of $2 in loonies! [That’s about 12 g.] In summer, the species is found in north temperate zone conifer and mixed conifer/hardwood forest feeding mostly on soft-bodied insects, particularly moths, but also midges and mosquitoes. Females form small, communal maternity roosts in tree hollows or under bark. In August and September they migrate back south to avoid our cold weather and lack of insects.
Knowing that Hallowe’en frequently seems like the coldest day of fall – it always seemed so to me as a parent taking kids around the neighbourhood! – all of our bats should either have found safe hibernation sites or have moved south by now. Most silver-haired bats should have left at least a month ago (end of September), long before our local ghosts, goblins, and witches start wondering our streets. And given that October weather is so hard on these little mammals, with the recent offering to the Museum collection as clear evidence, Hallowe’en and bats just don’t mix.
In Manitoba, Hallowe’en is a far scarier time for bats than it is for any of our trick-or-treaters.
When thinking of Manitoba’s owls, the great gray (our provincial bird) is usually the first to come to mind, whereas of the 12 species recorded for the province, the barn owl (Tyto alba) would likely be the last. Although barn owls have one of the widest ranges of any owl species, occurring in temperate and tropical regions around the world, they are very rare anywhere in Canada, and especially so on the prairies. They just don’t do very well in our climate; -35°C is hardly tropical or even temperate! There are only about a dozen records for barn owl in Manitoba since the first was found in November of 1912, and several of these are sight records only – they are convincing, but remain unconfirmed by photos or specimen evidence. There is one recorded (failed) nesting attempt in 1994 in Springstein, about 20km west of Winnipeg, and this is the last confirmed sighting. [See the excellent species account in The Birds of Manitoba available from Nature Manitoba (www.naturemanitoba.ca ).]
So imagine my surprise in mid-December when a report of an expired (and frozen) barn owl from a farm near Elie, Manitoba arrived in my e-mail inbox from Manitobabirds (a birding listserve)! The importance of the find was not lost on its discoverer, Mr. Dick Steppler, so he collected the bird and brought it to Jim Duncan of Manitoba Conservation. Jim has been banding and studying various owl species, particularly great gray and hawk owls for, well, probably longer than he’d care to admit, and has published several books and lectured extensively on these species. So Jim was the logical choice to notify about the barn owl, and, fortunately for the Museum, he has always been a great supporter of our collections, recognizing their value as both a repository and as a research tool. Our bird collection would soon contain Manitoba’s first record of barn owl for this century and the first in over 18 years!
But before it came to the Museum, it was off to Dr. Terry Galloway of the Entomology Department of the University of Manitoba. Among his many areas of expertise, Terry is an authority on external bird parasites, and because finding barn owls is so unusual, it was important to try to get as much information as possible from the specimen. Despite his careful inspection, this owl seemed free of external parasites.
I went to pick up the bird from his office and brought it back to the Museum. Under my and (mostly) Janis Klapecki’s guidance (our Collections Specialist), the bird would be prepared as a study skin by Laurel McDonald. Laurel is a wonderfully skilled volunteer who has been processing bird specimens for us over the last few years. Preparing a study skin is different from taxidermy, although it uses some of the same techniques; it is the finished product that is different. With the number of bird specimens we hold (over 6300), it would be far too time consuming and take too much storage space to create taxidermy mounts for each one.
The barn owl was found frozen, but had been thawed a couple of times, once by Mr. Steppler to clean and reposition the bird, and another time by Terry in order to wash it for external parasites. Because there was no certainty as to when the owl had expired, we had no idea of what condition it would be in or whether it could even be made into specimen. If it had been outside a long time, it could either have decomposed substantially or it might have “freeze-dried.” In either case, there would be little we could do but make a skeleton.
To our surprise, the owl was in quite good condition (for a dead bird!), meaning it probably had not been long on the ground before it was found, but just long enough to freeze. To make the study skin, the bird is thawed, an incision is made along the belly, and the skin is peeled back from the body and over the head to be turned inside out. The body, including skeleton is removed with only the lower leg bones, some wing bones and the skull remaining with the skin. The skin is then turned right-side-out, stuffed with cotton and stiffened with a wooden rod to be arranged to lie flat on its back. The vital organs are examined for internal parasites (we found none), checked for general condition, stomach contents examined (although this specimen had none), and the sex organs are checked to determine gender and measured to assess condition. We saved some tissue for future DNA work, in case that is required, and the bones not left with the skin will be cleaned by dissection and in the “bug tank”, a special sealed treatment area that houses beetle larvae that will eat the flesh off the bones to make a clean skeleton.
Barn owls, like many birds, are difficult to sex externally with any confidence. Because this bird was quite buffy with relatively large spots on its breast, we were pretty sure it was a female, but couldn’t be positive. In most birds of prey the females are larger than males. In barn owls, females are bigger on average, but there is considerable overlap in measurements between the sexes. Dissection conclusively determined that this owl was a female. Plumage also suggested that it was a hatch year bird, meaning that it was under one year of age when it died. Although the bird was very emaciated (it had no fat at all), it seemed otherwise in pretty good shape and likely died of starvation. There was some indication of trauma and bruising on the lower right leg, but the bone didn’t appear to be broken, so it didn’t seem enough to explain its death. There were two holes in the skin of the right wing that we initially thought might be due to decomposition after death, but because the rest of the bird seemed in good shape, these might have been indicative of injury – although there was no evidence of bleeding so these are likely to be postmortem. The exact cause of death will remain unknown.
It is certainly unfortunate that the first confirmed record of barn owl for Manitoba this century was an expired individual. But with the specimen now in The Manitoba Museum collection, it provides a permanent record of its occurrence and it is available for study by the likes of Jim Duncan or other owl specialists. Given the unlikely possibility of finding this specimen before it was carried off by a coyote or became buried or otherwise dispersed, one wonders how many other records of rare species like the barn owl are missed. Even specimens of common birds are extremely valuable for the Museum collection. In many ways, common birds can tell us more about our environment because we have the “luxury” of statistical power – one specimen is a curiosity or even anomaly, but several specimens can provide a pattern and tell a coherent story. And bird collecting, in the historical sense, just doesn’t happen anymore (probably for the good!), so the Museum collections grow slowly. But the addition of the rare finds like the Elie barn owl, along with window-killed specimens of common species make valuable contributions to our understanding of Manitoba’s birds.
Stay on the lookout for the unusual any time you are outside. You never know what exciting contributions you might make to our province’s natural history. A special thanks to the sharp-eyed Elie resident, Dick Steppler, who recognized the value of his discovery. Generations of researchers can now benefit from his thoughtful addition to the Museum collections.
Unless you happen to be chowing down on some steamed clams at the time, a discussion of important influences on human history is unlikely to include a clam as part of the conversation. But the eating habits of one small group of highly evolved clams has altered the travel plans of Christopher Columbus and Sir Francis Drake, changed the outcome of naval battles, and has inspired folklore and poetry.
Clams are members of the Bivalvia, a relatively diverse subgroup of molluscs that includes about 10,000 living species of oysters, mussels, scallops and any of the typical “seashells” we are used to finding washed up on beaches, whether on fresh- or saltwater. Other molluscs include snails, slugs, squids, and octopus. Bivalves are creatures that have two roughly symmetrical hinged shells (hence Bivalvia from the Latin bi = two, and valva = leaf of a folding door) that usually can enclose the entire animal for protection. Most are filter-feeders, meaning they take in great quantities of water through one siphon, pump it through the gills that strain out small food particles, and then send it out a second siphon.
But bivalves have been around a very long time, over 500 million years, and over that time some strange exceptions to the usual life history have evolved. One of these is an odd species known to scientists as Teredo navalis (from the Latin, teredo = woodworm or borer, and navis = ship), and known to sailors as “shipworm.” Despite the common name, this is NOT a worm, but a worm-shaped clam that has an elongate soft body up to half a metre long. The two valves of its shell have been modified from protective devices into two small, but extremely effective grinding surfaces at one end that are used to bore into any piece of wood encountered in the ocean. The clam starts out as a small juvenile that settles on a wood surface. As the new small clam bores into its new home, the wood is digested with the help of symbiotic algae that live on its gills. As the hole gets deeper, the animal’s body elongates to maintain a connection to the surface, and the burrow is buttressed with a shell-like lining.
As the common name “shipworm” suggests, and is emphasized by its scientific name Teredo navalis, this species has a long history of damaging ships. Some have suggested that the anxiety of Christopher Columbus’ crew to head west from Europe was not fear of the unknown, but fear of shipworm damage on a long journey, and for good reason. The fourth voyage of Columbus to the Americas in 1502 came to a disastrous end when all his ships sank due to damage resulting from Teredo. His ships were, “… rotten, worm-eaten … more riddled with holes than a honeycomb… With three pumps, pots and kettles, and with all hands working, they could not keep down the water which came into the ship, and there was no other remedy for the havoc which the worm had wrought… my ship was sinking under me…” (from a letter describing the voyage, http://mith.umd.edu/eada/html/display.php?docs=columbus_4thvoyage.xml&action=show). Columbus was forced by these small clams to land on Jamaica. He and his crews were marooned for a year before being rescued.
In 1579, Sir Francis Drake spent over a month on the Californian coast repairing the Golden Hind, which had been damaged by shipworms. And there are claims that shipworm appetites might have been a factor in the English defeat (more like repulsion) of the Spanish Armada in 1588. The Spanish had remained docked in marine waters off Portugal for several months before engaging the English, providing plenty of time for infiltration of ship’s timbers by the clam that would have weakened and slowed the vessels.
Even the eventual addition of copper cladding to naval vessels was not certain protection from the “worm”, as this famous poem by Henry David Thoreau (1817-1862) attests:
… The vessel, though her masts be firm,
Beneath her copper bears a worm …
Far from New England’s blustering shore,
New England’s worm her hulk shall bore,
And sink her in the Indian seas …
(excerpted from “Though all the Fates” 1849)
It has been estimated that ship timbers needed replacement every eight years on average, largely due to damage from Teredo wood-boring. At this rate, it is clear that this marine clam has had a tremendous impact on terrestrial ecology, too – huge tracts of coastal forests around the world have been cut down to replace damaged hulls of the ships of all the colonial powers as they travelled the seas. And all that travel introduced these clams all over the world as affected ships brought the animals with them. For this reason, scientists are uncertain of the original distribution and habitat of “shipworms.”
Of course, Teredo clams do not only target vessels, but any wooden structure in the sea. In 1731, parts of Holland were flooded because wooden dikes were eaten and weakened by “shipworm,” prompting replacement by costly imported stone. And perhaps Teredo was the cause of (or inspiration for) the famous hole plugged by the little Dutch boy’s finger. Damage to piers and moorings amounts to tens of millions of dollars per year. An infestation in San Francisco Bay between 1919 and 1921 caused over $2 billion of damage in today’s dollars, and repairing such damage is a considerable cost to this day.
The influence that a tiny bivalve mollusc can have on human history and economic activity is truly astounding. And this is only one of many examples from molluscs, a wonderfully diverse group of animals that is usually well outside our consciousness. I invite you to visit our temporary exhibit, “Marvelous Molluscs – the world is their oyster,” that introduces the amazing biology and fossil history of molluscs (open to April 7, 2013). Given how some have altered history, perhaps we should give these animals more of the attention they deserve.
For many Manitobans, the only connection we might have with Arizona involves a certain hockey team that left Winnipeg in 1996 for warmer climes. There are, though, other connections that involve organisms from the natural world other than coyotes as mascots!
I recently returned from a family vacation to southern Arizona where we were hoping to catch up with some of the local bird and lizard specialties, as well as enjoy the truly incredible environment that Sonoran desert has to offer.
Although we were a little early because of the mid-March timing forced by the school break, we had several species of hummingbirds, and I finally managed to see roadrunner – a “jinx” bird that I had missed on previous trips.
So the Arizona/Manitoba connection runs deep on many fronts. Much as humans find a way to chase a puck in the frozen north and the Phoenix desert, our sparrows manage to raise a family in the north every summer and eke out a living in the desert in winter. But unlike the puck chasers, the sparrows haven’t decided to move down to Arizona permanently.
A recent web-based discussion about the identification of an odd-coloured bluebird reminded me of a similar odd bluebird in the Museum collections. There are three bluebird species in North America: Eastern, Western, and Mountain. Contrary to what one might expect from their names, Manitoba is home to the Eastern and Mountain Bluebird, the Western being found in Canada only on the other side of the Rockies from us.
Males and females have different plumages in each species, but at least the males of all three species are quite easy to tell apart when the birds follow the rules and look like the picture in the book (or on the App, as the case may be!) and live where the maps say they must. But, as with so many organisms, variation is the rule, and sometimes things just don’t look quite as they should or show up where they should. That’s why so many people are interested in looking at birds (or insects, or almost any natural organism); they are endlessly varied and can sometimes make unexpected appearances.
What does this have to do with Museum collections? Because of that amazing variation, the specimens held in a museum are very useful for comparison and the museum collections themselves are a good place to deposit unusual specimens that might need a harder look later. Bluebirds are a good case in point. In the late 1960’s, an ardent bluebird worker in Manitoba, John Lane, found a very strange-looking male bird at one of his nest boxes. Its coloration suggested a hybrid between an Eastern and a Mountain Bluebird. Hybrids among bluebirds were not known at this time, and this was rare enough that he got in contact with the Museum and the unusual step was taken to collect the apparent hybrid, its Mountain Bluebird mate, and raise the young in captivity (for more details, see an article by John Lane in The Blue Jay, 1969, pages 18-21).
The hybrid male bird is certainly strangely-coloured. It has the quality of blue of an Eastern Bluebird, but rather than the typical rusty-orange throat and breast of this species, these areas are mostly blue, similar to the pattern of a male Mountain Bluebird. There are, however, some dashes of reddish mixed in. A look at the back shows the difference in blue colour of the Mountain Bluebird and the possible hybrid and Eastern birds.
The bluebird species also vary in size, although with overlap. Once the potential hybrid was at the Museum, measurements could be made to see where it might fit. As an example, wing length (measured officially as ‘wing chord’) for male Easterns ranges from 95-105 mm and for male Mountains ranges from 108-121 mm. The hybrid’s wing length, at 104.5 mm is at the high end of Eastern, but nowhere near the Mountain Bluebird size range. This same pattern holds for other measurements.
One possibility not considered by Lane is that the odd-coloured bluebird might be a hybrid of Western and Mountain. Western Bluebirds have a blue throat with an orange breast, and are slightly larger than Eastern Bluebirds, making the measurements fit that species. The blue breast of the hybrid would be the possible Mountain parent contribution. One issue with this is that Western Bluebirds usually have a rusty-orange patch on their shoulder or back, absent on the possible hybrid.
There is one more way that the hybridization question might be resolved with the Museum specimen. Dried skins, like these birds, can provide samples of DNA, the molecules that are the instructions for building and operating living things. Just as human DNA samples can identify a particular person or determine to whom they are related, animal DNA can be used to identify parentage. Perhaps a biologist interested in bluebirds will one day run a sample of DNA and help to solve which species might have hybridized to make our strange specimen.
But without the specimen in a museum collection, we would never have the chance to check.
As curators of some sizeable collections (>100,000 in Zoology alone), we are frequently asked what the most valuable specimen or most important one among them might be. Certainly, the collection contains several items that are “one-ofs”, or are the biggest, or most colourful, or even worth a good deal of money in the marketplace. But value, like beauty, is in the eye of the beholder.
We recently received a request for a few feathers off of a single specimen of Ivory Gull (Pagophila eburnea) collected north of The Pas in 1926, the only specimen we have of this species. The Ivory Gull is a High Arctic breeder that has made an appearance in Manitoba only about a dozen times in the last 100 years. The species is listed as Endangered in Canada and its populations are declining. A research group is examining levels of mercury and stable isotopes of carbon and nitrogen in feathers to investigate the possible role of heavy metal contamination and changes in foraging behaviour in Ivory Gull decline. The Manitoba Museum specimen is one of only about 150 specimens from Canada in all the museums of North America, and its age makes it particularly valuable for reconstructing historic levels of contamination and isotopes. Who could have predicted the value of this Museum specimen for conservation of the species when it was collected those many years ago?
By sharing information on Museum rarities with researchers who can pool data from the few specimens available in collections from around the world, we learn more about the biology of the organism, making the specimen more ‘valuable’ in terms of information and helping conservation efforts. The Museum ends up with another story to tell about its collection and about the animals themselves. Science, the Museum, and, most importantly, the animal will all win from this exchange.
Nature generally can be understood through patterns. Unique observations, like a rare gull found north of The Pas in 1926, are curiosities, but can’t contribute very much to the bigger picture as an isolated event. Even the proverbial apple clunking onto Newton’s head, though important as a unique event, only becomes truly valuable when its act of falling towards Earth can be generalized to explain why other things also fall.
This helps to explain why the Museum has, when possible, more than one example of a species, and continues to grow collections through active collecting. Just as a single letter is more as a part of a word, or a word is more meaningful when put into a sentence, a specimen becomes more in the context of a collection. A particular specimen does have value in and of itself as a record of occurrence in a single place at a single moment (called a voucher), or sometimes even has monetary value. But several specimens from different places collected at different times provide a more complete story of species variability, distribution, biology, and, as in the case of Ivory Gull mercury levels, how these might have changed over time and space. Each individual provides a data point, and an important one, but the real value comes from the collection as a whole. And a new specimen added to the collection today, while not necessarily individually significant right now, might be so 100 years from now, just as the Ivory Gull specimen collected in 1926 is valuable today.
Richard Fortey (a paleontologist at The Natural History Museum, London) suggested that natural history museums are the archives of the Earth, an apt metaphor. Through their collections, museums document individual “events” as specimens, which together tell the story of how our natural world changes over time. The Manitoba Museum plays this critical role as natural history archive for the province. Specimens old and new are together a feather in our collective cap.