Text and photos by Orla Osborne
Studying the Coats Island Murres
The Thick-billed Murres (Uria lomvia) of Coats Island, Nunavut (Northern Hudson Bay), may give the impression that everything may be black and white, but don’t be fooled, the unknown, the grey of global warming, casts a warning light over their low lying Arctic colony. It’s not just the weather that is changing and unpredictable — the animals are too. Ecosystem changes and scarcity of prey are causing some Arctic predators to alter their normal patterns of behaviour, leading to changes in long-established interspecies relationships.
Rising temperatures appear to benefit some species and harm others. Some may be coping successfully with the changes occurring in their surroundings. For others, a new predator may move into the neighbourhood or parasitism may increase for the less fortunate. In 2011, the Thick billed Murres of Coats Island, in Northern Hudson Bay, Nunavut, were found to be dealing with both.
When the bears and bugs moved in to take over dining privileges at the colony, their former predators, the gulls and foxes, took a back seat though they in paradox actually benefited from the devastation inflicted upon the colony because the visiting polar bears had killed more birds than they could possibly eat, while mosquitoes had driven parenting murres to abandon their young.
The Thick-billed Murres, a foot-tall, tuxedo-clad, predator and prey species, have been nicknamed the Penguins of the North. However, unlike penguins, they fly, resembling black and white footballs zooming through the air overhead at outrageous speeds reaching 75 kilometres per hour; flapping madly as they struggle to stay airborne. In stark contrast to their aerial manoeuvres, Murres will dive to depths of up to 150 metres in search of prey. Their narrow wings that are fin-like in appearance are adapted for flight and also for underwater propulsion. Their body is sleek and streamlined, unhindered by a long tail, with short overlapping feathers that provide a perfect waterproof seal, having been treated with a special waterproof sealant secreted from an oil gland above their tail and applied to every feather through meticulous preening. Their webbed feet are positioned as far back as possible — to reduce drag while diving without compromising their ability to stand upright and clumsily shuffle about the rock ledges. They, along with other members of the Alcidae family (Puffin, Auk, Razorbill, and Murrelets), are the champions of diving seabirds, matched in water only by their non-flying Antarctic brethren, the Penguin.
Thick-billed Murres migrate from a solitary offshore existence. During the winter they ride the whitecap waves of the mid-North Atlantic braving winter storms to reach land and perch on a bustling, crammed [estimated 30,000 pairs] cliff-face during summer to breed. During their migration, they travel thousands of kilometres, to the exact spot on the same rock ledge on the cliff face of the same colony they’ve chosen every year since they found their lifetime partner, a routine that, for many birds, can last for over 30 years and is broken only by death of its partner or its own demise. Incredibly they will nest, on average, less than five metres away from the exact patch of bare rock they themselves hatched! Given that their first three years are spent entirely out at sea, that is a phenomenal accomplishment of spatial memory.
During the fledging period, when the chicks are ready to leave the comforts of their bare rock ledge, they apprehensively step off the edge and proceed to flutter (or if unlucky tumble) to the water a few 100 metres below. Dad, who had been coaxing the chick to undertake such a daunting venture, waits patiently. A dialogue between the father and offspring is strengthened in the upcoming days to the event, and from the moment the chick leaves the ledge, to their reunion in the water below, this dialogue must be constant, otherwise the chick is unlikely to find their father when its surroundings look like a swirling kaleidoscope of black and white.
And for the same reason these chicks are prevented from gracefully taking to the air as they depart their nest for the first and last time, they also make their very first migration by webbed foot, as they paddle the first 1,000 km southward. Why? Well, they can’t fly yet, they’re only three weeks old.
In 2011, it was obvious that these birds were caught between a rock and a hard ledge, on a treacherous cliff face – fending off flesh feeding predators. In the average day of a breeding murre, foxes patrol the upper cliff boundaries, while pirate-like gulls ride the updrafts on windy days in search of unguarded eggs and tiny chicks. When desperate, they drag a dutiful parent off their ledge and away from their vulnerable progeny. At the best of times, the Murres make but a small sacrificial contribution towards sustaining the gull and fox population of Coats Island. At the worst of times they have hungry polar bears to contend with. The bears are not restricted by wind or limited by a fear of heights. They are deceivingly agile rock climbers, which due to their waddling pigeon-toed gait does surprise.
Not being overly familiar with this unlikely predator, the resting birds sit side by side the intruding bear, looking slightly bewildered by its great white fuzzy mass and its wide gaping jaws. For those particular birds and their eggs it is already too late; there was never enough time to even contemplate the significance of this beast’s presence.
Only in recent years, since 2000, have scientists been occasionally seeing these bears clamber with ease about the ledges of the colony. Within a matter of minutes, ledges once full of tightly knit birds standing shoulder to shoulder, each incubating an egg or protecting a small fluffy chick, lay bare and exposed, as adults and chicks alike are scattered, mauled or eaten as a bear passes through.
During the 2011 breeding season, the destruction caused by the intruding bears led to a massive increase in the death rate of the Murres; 1.25 per cent (about 500 birds) of the breeding Murre population was killed and an estimated 30 per cent of breeding attempts failed in consequence.
The bears not only confounded many of the ongoing research projects at the colony, but they also posed a personal safety problem for the scientists. The rules were strict in the summer of 2011, a loaded and safety off ready shotgun was to be carried at all times. No exceptions. Prior field expeditions had not warranted such extreme safety measures, a can of bear spray was sufficient, but things had changed. It wasn’t until the end of the field season that it was realized that two bears were actually living on the colony, one at either end. Not your ideal summer getaway, for bird nor human.
Mosquito parasitism of the Murres has become more intense since the 1990s as well, and the swarms are emerging up to 30 days earlier than two decades ago. Consequently, the bug-free grace period that the Murres once enjoyed had vanished, a crucial time when the birds diligently incubate their one and only egg of the season, protecting it from the elements, predation and from rolling off the cliff edge. With an increase in mosquito attacks, more incubating adults are driven from the cliffs to seek respite away from land. This can spell disaster for the developing, unhatched chicks. Not only are predators in greater numbers on the prowl, but also UV rays from the sun are harmful enough to cause embryonic death. It takes only one day of exposure.
Some birds, however, are not so easy to deter, and apparently they would sooner die than give up the chance to raise a little one. These are the ones that have finally figured out what parenting is all about. Those above the age of 18 years old, these birds are the ‘oldies’; they have a much higher rate of reproductive success than the younger parents at the colony and these little warriors were amongst the hardest hit.
It would appear that, under the circumstances, ‘Survival of the fittest’ has been flipped upside down and spun 180 degrees, a trait such as being better at incubating than other birds would ordinarily have led to more offspring, but now it leads to an increased risk of death, while abandonment may decrease reproductive success but increases the chance of living to see another sunset. The balance? A faster rate of population decline.
How mosquitoes are affecting the birds is not so clear-cut. They don’t seem to be poisoning the birds as such. However, they are stressing the birds, causing dehydration, weight loss and a compromised physiological condition, all of which leads to the desertion of eggs and chicks, or the eventual death of breeding adults.
You are likely wondering what business the bears had harassing these defenceless relatives of the beloved “Happy feet” penguin family, and why the bugs were so much worse in 2011? As Tony Gaston and Kyle Elliott, my companions on Coats Island, explain in a published scientific paper, a succession of higher-than-average summer temperatures led to an escalated growth rate and early emergence of the mosquito population on Coats Island.
It was also the record-breaking temperatures that caused the early break up and reduced extent of sea ice in Northern Hudson Bay. It was thought that the polar bears were likely driven from their icy feeding grounds and into a terrestrial existence much earlier than usual. This finding is significant. It counters what many ecologists had been predicting about the effects of global warming on animals feeding at different levels of the food web (i.e. trophic level). To many scientists, it seemed logical that top predators would respond more slowly. This apparently is not the case.
There are many predictions for how species will react to global warming, and which factors will impact the natural order the most. For Gaston and Elliott it is clear that changing species interactions is having a much stronger impact on the Murres than either a direct physiological effect or a shift in range. Based on what has been observed at Coats, Gaston warns that predicting how species will react to global warming is likely to be a lot more complex than what we currently believe. In other words the only certainty is uncertainty.
The results of Gaston and Elliott’s research demonstrate that the Thick-billed Murre colony witnessed an increase in the reproductive failure and mortality rate by an order of magnitude. In the 30 years that the colony has served as a research station, never has it seen so much devastation by polar bears or mosquitoes. Should these conditions persist, the colony will be faced with a 50 per cent decrease in population size over the next 25 years. That’s a drop from 30,000 breeding pairs to 15,000. They point out that the “potentially catastrophic effect of increasing predation and parasitism” at Coats Island demonstrates how changing species interactions are a direct consequence of increasing global temperatures. As for the Murres of Coats Island… perhaps one might venture to say they are perched on the ledge of destruction?
My return to Coats
When the opportunity arose to return for another field season at Coats in 2013, I initially rejected the idea. My alter ego self was warning me against such poor reasoning. Was I not lucky enough to have survived the 2011 season? In the end my sense of self-preservation was defeated by my burning curiosity and gameness for adventure. I was going back to Coats.
Our bear guide, Joe Nakoolak, a resident of Coral Harbour who has been working on Coats with scientists for about 25 years, set us all at ease during the flight with his predictions of a relatively bear free season ahead of us. His reasoning, more ice means less bears on the colony. That made sense to me, I felt immediately better about my decision to return.
A quick survey around the colony and camp, confirmed our suspicions. There were no bears; the mosquitoes, however, seemed to be out in full force to welcome us back. As for the Murres, they seemed not to be doing as well as usual, many nest sites were vacant and most of the birds were well behind in their breeding schedule. It appeared that what was causing the Murres to lay their eggs so late in the season was also keeping the bears at bay. The summer of 2013 had been late in coming, and with it, a late break up of sea ice, a boon for polar bears whose primary prey are seals hunted over sea ice. So, as Joe explained to us previously, with bellies full of seal meat, the bears had no need to risk their lives clambering around cliff faces scrounging for eggs and birds. This may seem like a saving grace for the Murres, no bear and less bugs, but the effect of a shortened breeding season likely came at a cost too. As I wandered around the colony taking all of this in, it became immediately apparent how finely tuned species are to their environment, and also how two Arctic species can respond so differently to the same change within their shared environment.
It takes only two offspring, out of numerous attempts, to replace their parents in order for the population to be sustained. What fascinated me the most about the stark contrast of my two experiences at Coats was that although the odds seemed against the birds in being able to reproduce and raise a chick to fledging, the majority of the colony were successful both years.
Scientists have warned that climate change is likely to result in unpredictable weather patterns and environmental conditions. Our climate has always been in a constant state of change, and yet many species have persisted for millions of years nonetheless. Climate change, as we are currently experiencing it, is thought to be occurring at a perilously accelerated rate, and this poses one of the biggest challenges facing species that may not have enough time to adapt.
On the brighter side however, the resilience that species have evolved in order to buffer themselves from such events will hopefully see many through the direct and
indirect hardships climate change may throw at them.
Nature never really is in perfect balance, and the Murres can’t rely on perfect conditions every year, but it is the ability of this species to buffer itself from deviations from the ideal that sustains this colony. How resilient a species or population or individual might be in the future is unknown and hard to predict — the very facts that give us cause to pause and consider the impacts of climate change. Can we afford to ignore the potential consequences? I certainly couldn’t ignore it on Coats Island, and hopefully as you’re reading this you’re giving it some consideration too.
Born in and raised in Ireland, Orla Osborne moved with her family to Iqaluit as a young teenager and has been living there on and off ever since. During and after completing her degree in marine biology and ocean science at the University of Victoria, she has worked for the Canadian Wildlife Service, World Wildlife Fund, and the Department of Environment for the Government of Nunavut doing contract work as a field technician and research assistant.