Tag Archives: nature

Animals with white winter camouflage could struggle to adapt to climate change

Animals that turn white in the winter to hide themselves in snowy landscapes could struggle to adapt to climate change, research suggests.

A new study finds that declining winter snowfall near the Arctic could have varying effects on the survival of eight mammal species that undergo a seasonal colour moult from summer brown to winter white each year.

Species most at risk of standing out against the snow include mountain hares, snowshoe hares and short-tailed weasels. Without blending into the background, these animals could find it harder to hunt prey or hide from predators.

However, there are some parts of the northern hemisphere where colour-changing mammals could have a better chance of adapting to climate change, the study finds.

These “rescue” hotspots, which include northern Scotland and parts of North America, should be protected by conservationists to give colour-changing animals the best chance of adapting to future climate change, the lead author tells Carbon Brief.

Turning white

Visual camouflage is a vital tactic used by both predatory animals, who must hunt while avoiding detection, and their prey, who must hide to avoid being eaten.

But in parts of the northern hemisphere, the changing of the seasons offers a unique challenge to those trying to camouflage with their surroundings.

In winter, when the landscape is snowy and barren, animals with white colouring find it easiest to blend in. However, when spring arrives and snow is replaced with brown soils and growing vegetation, those with mottled brown colouring tend to find it easier to escape detection.



One solution to this problem, used by a range of animals, is to undergo a seasonal molt from brown to white each year.

Scientists have recorded 21 mammal and bird species using this colour-changing tactic, including the Siberian hamster, the collared lemming and the willow ptarmigan.

The new study, published in Science, focuses on how climate change could alter the survival chances of eight of these species.

Climate change is causing a decline in winter snow cover in Arctic regions, along with the earlier onset of spring each year. This decline could be causing a “mismatch” between animals with white coats and the snowless ground, explains lead author Prof Scott Mills, vice president of research for global change and sustainability at the University of Montana. He tells Carbon Brief:

“All of these species literally live or die by the effectiveness of their camouflage, which evolution has exquisitely crafted to match the average duration of winter snow.”

This mismatch could make some animals, such as hares, more vulnerable to predators, he says. It could also make it harder for predators, such as the arctic fox, to effectively hunt their prey. Mills says:

“One thing to realise is that all 21 of these species, including the carnivores, are prey: Arctic fox get clobbered by golden eagles, weasels are killed by foxes, coyotes, and raptors. For the hares and rodents, tasty snacks for multiple predators, camouflage is everything.”

Arctic fox (Alopex lagopus) in snow, Churchill, Manitoba, Canada, North America. Credit: robertharding / Alamy Stock Photo

Charting colour change

For the study, the researchers first collected coat colour and location data for more than 2,500 live animals and museum specimens spanning 60 countries.

They then analysed this data using modelling to study the moulting behaviour of animals living in different parts of the world.

The researchers found that, within one species, not all individuals will moult in the winter.

The chances of an animal moulting depend on the landscape in which they live. The more snowy the landscape, the higher the chance an animal will turn white in the winter.

This is shown on the chart below, where the number of snow-covered days per year is plotted against the likelihood of turning white in the winter for the Japanese hare (dark blue), the white-tailed jackrabbit (light blue), the least weasel (yellow) and the long-tailed weasel (red).

The probability of a colour-changing mammal having a white winter coat in regions with 0-320 days of snowfall per year. Results are shown for the Japanese hare (dark blue), the white-tailed jackrabbit (light blue), the least weasel (yellow) and the long-tailed weasel (red). Source: Mills et al. (2018)

The chart also includes a “broad polymorphic zone”. A “polymorphic zone” is a term used to describe regions where the probability of having either a brown or white winter coat is close to equal.

In these “zones”, mammals could have the best chance of adapting to declining snowfall conditions, Mills says. That is because, in these areas, a proportion of each species do not turn white in the winter and are therefore more able to blend in with snowless environments.

These brown-coated animals will be more likely to survive winters with less snow cover and pass on their genes to their offspring. Over time, this would increase the proportion of animals with brown winter coats, allowing the population to adapt – and ultimately survive – in environments with less snow.

The maps below show where the polymorphic zone of two or more species overlap. On the charts, red shows where the zones of two species overlap, while brown shows areas where the zones of three species overlap.

Regions in North America (A) and Eurasia (B) with polymorphic zones in winter coat colour for more than two species (red) and more than three species (brown). Source: Mills et al. (2018)

The charts show that parts of the US, Canada and Scotland show the largest overlap.

These regions could be considered “evolutionary rescue zones” where a number of colour-changing mammal species could be able to adapt to declining snowfall, says Mills:

“Because areas with the most [coat colour] variation evolve most quickly, these ‘polymorphic’ zones emerge as hotspots for rapid evolutionary response to climate change. Here in the polymorphic zones the populations are most likely to rapidly evolve towards winter brown, and to disperse the winter brown genes out into the adjacent winter white populations.”

The species whose range most commonly fall into these zones include the arctic fox, the white-tailed jackrabbit and the long-tailed weasel, the research finds. These species may have the best chance of adapting to declining winter snowfall, Mills says, but it is still too soon to tell what their chances of survival could be:

“To really evaluate risk to various species will require a lot more fieldwork and genetic analyses for other species, like we’ve been doing with snowshoe hares. We’re starting to work with weasels and Arctic fox, but I really hope that this paper initiates researchers around the world to start investigating coat colour mismatch.”

Picture of change

The findings should provide “yet another push to policymakers” to reduce the “global carbon footprint”, Mills says:

“I hope that the picture of white animals on brown snowless ground ‘paints a thousand words’ that shows that with continued human-caused climate change and reduction in snow duration, winter white animals on a brown snowless winter background will be in trouble.”

The research also shows that conserving “evolutionary rescue zones” could help wildlife to survive future climate change, Mills says:

“I hope it also helps [policymakers] see that other short-term, yet effective, options are available for protecting wildlife in the face of climate change.”

The post Animals with white winter camouflage could struggle to adapt to climate change appeared first on Carbon Brief.

Book Review: Smart Swarm – Using Animal Behaviour to Change our World

Smart Swarm is written by Peter Miller who is a senior editor of National Geographic. In his book Miller asks the question ‘What can we humans learn from the intelligent behaviour observed in nature, and in particularly in the complex, chaotic, bewildering, bamboozling and often enchanting and breathtaking displays of ants, termites, bees, starlings, fish and locusts. The answer it would seem, would be an awful lot, as suggested by Don Tapscott in the foreword:

Loosening organisational hierarchies and giving more power to employees can lead to faster innovation, lower cost structures, greater agility, improved responsiveness to customers, and more authenticity and respect in the marketplace.

While there have been many scientific books on the subject such as Stuart Kauffman’s At Home in the Universe and Signs of Life – How Complexity Pervades Biology by Richard Solé and Brian Goodwin, and there have been many books in the general area of complexity science and chaos theory which have become global best-sellers, there have been far fewer written for the layperson, and especially those in business looking for inspiration to develop new business models or solve complex organisational issues such as logistics, crowd control, customer boarding of planes, power grid management and group decision making to name just a few areas Smart Swarm covers.

Miller divides his book into a number of chapters, which focus on one particular type of behaviour seen in swarms, flocks and schools. This allows him to examine the main lessons which he divides into self-organisation, seeking a diversity of knowledge in decision making (avoiding groupthink), indirect collaboration (and decentralised control), adaptive mimicking . Miller’s analysis is clear, precise and always engaging, and so we learn how in ant colonies, a large number of individuals without supervision can accomplish complex tasks when they meet and interact just by following a few simple rules; we learn that ants are also able to solve logistical problems through ingenious solutions, problems that we humans struggle with even with access to a huge amount of computational power; we learn how honeybees are able to make optimal decisions which are critical to their survival through a “friendly competition of ideas”.

We also learn how by paying close attention to those around us, just as starlings are able to do, we can make decisions rapidly in times of uncertainty. However, as seen in the study of the dark side of collective behaviour, the destructive tendencies of locusts, we also can learn how to mitigate against following the crowd uncritically, getting caught up in fads or financial schemes.

Miller then provides many different examples in human society which have either been directly inspired by modelling swarm behaviour, or which reflect the key principles. For example:

  • Southwest Airlines developed a new method for allocating seats to passengers based on modelling ants.
  • Air Liquide used a model based on ant behaviour developed at Santa Fe Institute to reduce logistic and transport costs by around $20 million.
  • Just as termite mounds are self-healing, Electric Power Reserch Institute are examining the possibility of making the US electricity grid, the most complex man-made structure in the world, self-healing.
  • Employees at Best Buy predicted sales with 99.5% accuracy, 5% more than experts.

For Miller there are two key lessons we can learn. The first is that by working together in smart groups, either very small and focussed or of a massive scale, we can lessen the impact of uncertainty, complexity and change. The second lesson is that in nature, good decision making comes as much from competition as much as from compromise, from a friendly form of disagreement as much as from consensus. The trick therefore is not to blindly copy one type of decision making tool or framework which copies one instance in nature, but to really attempt to make sense of the particular instance or issue and match that to the related way in which nature solves similar problems.

I can strongly recommend Smart Swarm to anyone who is interested in the areas of organisational development, business strategy, process design and problem solving. For those who wish to develop their interest further, I would then suggest reading The Nature of Business – Redesigning for Resilience by Giles Hutchins. Giles’ book is divided up into nine modules, and therefore offers a highly practical guide for then putting these insights from nature into practice in businesses and organisations.

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Polar bears could be struggling to catch enough prey, study shows

Polar bears could be failing to hunt enough seals to meet their energy demands, new research suggests.

A study tracking the behaviour of nine female bears from 2014 to 2016 over the Beaufort Sea found that some of the animals exerted so much energy during the hunting season that they lost up to 10% of their body mass in an 8-11 day period.

Polar bears live on a diet made up of ringed seals, which they hunt from the ice surface. However, sea-ice cover in the Arctic is falling at a rate of 14% per decade. This may be forcing some polar bears to travel further in order to find their prey, the authors of the new research say.

Female bears who lose large amounts of weight during the spring hunting season could find it more difficult to raise their cubs to maturity in the following months, the lead author tells Carbon Brief.

However, it is not yet clear how such changes could be affecting the long-term survival of adult polar bears, he adds.

Polar bear with a GPS-equipped video camera collar, lying on the sea ice of the Beaufort sea. Credit: Anthony Pagano, USGS.

Bear’s-eye view

Polar bears live across the Arctic and spend the spring and early summer months hunting ringed seals, which provide the animals with a high source of energy and fat.

When autumn arrives, pregnant bears will enter the “denning” season. At this time, females will build themselves a maternity den out of snow, which is where she will give birth to her cubs and nurse them until the following spring.

Though previous studies have looked at the hunting activities of polar bears during the spring months, the new study, which was published in Science, has revealed these habits in striking detail.

The research followed the behaviour of nine female bears living in the Beaufort Sea area for a period of 8-11 days at some point between 2014 and 2016.

To track the bears’ day-to-day activities, the scientists fitted the females with GPS-equipped video-camera collars and accelerometers. They chose to study females because male polar bears’ necks are “larger than their heads” and so they are unable to retain collars, according to the research team.

The video-camera collars allowed the researchers to collect a large amount of data, including how far each bears tends to roam across the ice, how much time they spend walking and swimming and how often they come into contact with other bears.

The camera footage also allowed the scientists to observe the techniques bears use when trying to hunt seals. Most of the time, polar bears catch their prey using the “sit-and-wait” tactic, says lead author Anthony Pagano, a PhD candidate at the United States Geological Survey (USGS) and the University of California, Santa Cruz. He tells Carbon Brief:

“Polar bears walk around until they find a breathing hole that a seal is actively using and they’ll typically stay there, they’ll either sit down or lay down or stand, and they’ll wait at that breathing hole. In some cases, they wait for hours.

“If they detect a seal has come out to breathe, they’ll stand up on their hind legs, raise their bodies up into the air and then pounce through the water as a way to try to stun the seal. If they’re successful, they’ll try to grab the seal around the neck with their jaws and pull them out of the water.”

The video below shows the polar bears in action:

In order to collect this data, the researchers had to capture the bears at the start and end of the study period. Catching the bears required the team to track the animals using a helicopter, Pagano says:

“The easiest way to catch the bears is from a helicopter. It’s the safest method both for the bears and for the biologists. It’s also the best way to try to locate bears as well. Bears occur over a pretty extensive landscape and so locating the bears is a serious challenge.”

Bustling bears

The recorded field movements of each bear over the two-year study period are shown on the diagram below, where each colour represents the movements of one bear. On the diagram, the black bear symbol shows where a bear was captured while the white bear symbol shows where they were recaptured.

Diagram showing the field movement of nine female polar bears in the Beaufort Sea area in April from 2014-2016. On the diagram, the black bear symbol shows where a bear was captured while the white bear symbol shows where they were recaptured. Source: Pagano et al. (2018)

The data collected by the researchers suggest that polar bears are more active than previous research has suggested, Pagano says:

“Previous modelling work has tried to guess what a polar bear’s energy expenditure might be and how many seals they might need to capture. They speculated that, because polar bears use the ‘sit-and-wait’ hunting tactic, they would be able to conserve energy.

“What we found in the study is that the activity rates of these bears are very similar to other terrestrial carnivores, despite this sit-and-wait approach to hunting. They are still quite active and they are still travelling long distances.”

In fact, the study finds that polar bears burn energy at a rate that is 1.6 times that of what previous research has suggested.

However, the activity rates of the bears may have been affected by the capturing process, the researchers note in their research paper:

“Admittedly, the activity levels…in the study may be biased low owing to the effects of recovery post-capture. On the basis of movement rate and activity sensor data, recovery post-capture for polar bears may last two to three days.”

Melting ice

Using the new estimate, the researchers predicted that a solitary female bear would need to eat, on average, either one adult seal, three subadult seals or 19 newborn seal pups every 10-12 days to gain enough energy to maintain her current weight.

However, in the study period, more than half of the bears did not eat enough seals to meet their energy needs and subsequently lost body mass. Four bears lost more than 10% of the 8-11 day study period, with an average loss of 1% per day.

Previous research also shows that, in recent years, female bears have been more likely to enter the “denning” season with inadequate fat reserves than in previous years, Pagano says.

The rate of Arctic sea-ice melt over the spring and summer has been increasing in recent decades. Pagano suggests that this could be forcing the bears in the region studied to travel further to find food, and, therefore, be causing them to lose body mass at a faster rate than previously observed. He says:

“In this area, 80-90% of the population is following the ice as it recedes to the north. They’re moving much greater distances than they had historically to follow the ice as it retreats hundreds of kilometres further to the north than it did historically.

“Once the ice returns in the fall and the winter, they’re following the ice back and making a long distance migration back to areas that are thought to have a higher variability of seals.”

Cub survival

Losing weight during the spring months could leave female bears without the adequate resources needed to raise their young in the “denning season”, Pagano says, which could be causing declines in cub survival:

“Some work has shown that they are emerging from their dens in lower body condition and they are not able to locate as much food as they have done historically. Basically, they’re not able to provide for their young at an adequate level and that’s driving declines in cub survival.”

The threats facing polar bears in this region are likely to worsen as climate change continues, he says:

“The concern is that as the ice breaks up earlier each year, the bears will be impacted in three ways: they’ll be less successful at catching seals because they’re being displaced from their primary foraging habitat earlier; they’re putting on less weight than they would have done historically; and then they’re also moving greater differences. If that trend continues, we would expect continued declines in reproductive success.”

However, it is less clear how these changes could impact the survival rates of adult bears, he adds:

“From what we’ve seen so far there doesn’t seem to be large decreases in adult survival, it really seems to be a function of females to be able to produce offspring and successfully raise them.”

Research from the International Union for the Conservation of Nature (IUCN) polar bear specialist group shows that polar bear populations in the southern Beaufort Sea are “likely to decline” in the future. Carbon Brief has previously published an article examining how climate change could affect polar bear population numbers.

Polar bear wearing a video camera collar, hunting for seals on the sea ice of the Beaufort sea. Credit: Anthony Pagano, USGS.

‘Brief’ study

The findings could tell scientists more about how “polar bears are responding to climate change”, says Prof Charlotte Lindqvist, a biologist from the University at Buffalo in New York, who was not involved in the research. She tells Carbon Brief:

“The sample size is small, but what can you do when you sample rare and wild polar bears on the sea ice? If half of the studied bears are already showing signs of energy deficiency on the spring sea ice, we can only imagine a likely gloomy outlook for polar bears as sea ice continues to decline.”

The “major strength” of the research comes from the integration of several different methods to gain greater insight into the behaviour of polar bears, says Prof Andrew Derocher, a polar bear biologist from the University of Alberta, who was not involved in the current study. He told Carbon Brief:

“One challenge with the study findings is that we know that feeding varies widely over space and time with polar bears and the study period used was, by necessity, quite brief. Some of the results could be rather different a few weeks or a month later. However, none of this detracts from the study’s findings, but context is useful.”

The research highlights that the challenges facing polar bears are “complex” and scientists are “yet to fully understand them”, he adds:

“Arctic sea-ice loss is a global issue and there is no quick fix: no protected areas, no habitat modification, or other standard conservation approach could significantly alter the threats facing polar bears in a warming climate. Only the reduction of greenhouse gases can slow the rate of loss of polar bear habitat and improve the conservation outlook for the bears.”

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Climate change and deforestation threaten world’s largest tropical peatland

Just over a year ago, scientists announced the discovery of the world’s largest intact tropical peatland in a remote part of the Congo’s vast swampy basin.

The Cuvette Centrale peatlands stretch across an area of central Africa that is larger than the size of England and stores as much as 30bn tonnes of carbon.

Now, the same research team has published a new study finding that future climate change, along with deforestation, could threaten the peatlands’ ability to soak up and store large amounts of carbon.

If left unaddressed, these threats could cause the Congo peatlands to turn from a carbon sink to a carbon source, the study says. This means that the peatlands could contribute to climate change by releasing more carbon than they are able to absorb.

Protecting the peatlands from climate change will require “an international effort to reduce greenhouse gas emissions”, the lead author tells Carbon Brief.

Peat power

The Cuvette Centrale, which spans both the Republic of the Congo and the Democratic Republic of Congo (DRC) (see map below), is the second-largest tropical wetland in the world.

Location of the Cuvette Centrale wetlands in Africa (in green) Source: Dargie et al. (2017)

The peatlands within the Cuvette Centrale covers 145,500 sq km and contains 30% of the world’s tropical peatland carbon, according to the 2017 Nature paper. This is equivalent to about 20 years’ worth of US CO2 emissions from burning fossil fuels.

Across the world, peat covers just 3% of the land’s surface, but stores one-third of the Earth’s soil carbon.

Peat is a wetland soil made of partially decomposed plant debris. It is usually found in cooler, waterlogged environments, explains Dr Greta Dargie, a research fellow from the University of Leeds and lead author of the study published in the journal Mitigation and Adaptation Strategies for Global Change. She tells Carbon Brief:

“Under waterlogged conditions, the usual decomposition of dead trees and leaves is slowed, meaning there is a build-up of carbon-rich material which we call peat. A long slow build-up means that peatlands store enormous quantities of carbon.”

Heating up

Glossary

RCP2.6: The RCPs (Representative Concentration Pathways) are scenarios of future concentrations of greenhouse gases and other forcings. RCP2.6 (also sometimes referred to as “RCP3-PD”) is a “peak and decline” scenario where stringent mitigation and carbon dioxide removal technologies mean atmospheric CO2 concentration peaks and then falls during this century. By 2100, CO2 levels increase to around 420ppm – around 20ppm above current levels – equivalent to 475ppm once other forcings are included (in CO2e). By 2100, global temperatures are likely to rise by 1.3-1.9C above pre-industrial levels.

RCP2.6: The RCPs (Representative Concentration Pathways) are scenarios of future concentrations of greenhouse gases and other forcings. RCP2.6 (also sometimes referred to as “RCP3-PD”) is a “peak and decline” scenario where stringent mitigation… Read More

Future climate change presents one of the largest threats to the Congo peatlands, the new study finds.

The latest assessment report (pdf) from the Intergovernmental Panel on Climate Change (IPCC) finds that the region could warm by around 0.5C from 2000 to the end of the century under a low-emissions scenario (RCP2.6) and by 4.5C under a high-emissions scenario (RCP8.5).

It is less clear how global warming could affect rainfall in the region, but research (pdf) suggests that the peatlands could experience an overall reduction in rainfall and an increase in the number of dry periods as the climate warms.

Glossary

RCP8.5: The RCPs (Representative Concentration Pathways) are scenarios of future concentrations of greenhouse gases and other forcings. RCP8.5 is a scenario of “comparatively high greenhouse gas emissions“ brought about by rapid population growth, high energy demand, fossil fuel dominance and an absence of climate change policies. This “business as usual” scenario is the highest of the four RCPs and sees atmospheric CO2 rise to around 935ppm by 2100, equivalent to 1,370ppm once other forcings are included (in CO2e). The likely range of global temperatures by 2100 for RCP8.5 is 4.0-6.1C above pre-industrial levels.

RCP8.5: The RCPs (Representative Concentration Pathways) are scenarios of future concentrations of greenhouse gases and other forcings. RCP8.5 is a scenario of “comparatively high greenhouse gas emissions“ brought about by rapid population growth,… Read More

A combination of less rainfall and higher temperatures could cause parts of the peatlands to dry out, which could reduce the rate of plant decomposition and, therefore, the rate that the peatlands can absorb carbon from the atmosphere.

Drier conditions could also prompt the peatlands to start releasing larger amounts of carbon, says Prof Simon Lewis, a study author from the University of Leeds and University College London, and one of Carbon Brief’s contributing editors. He tells Carbon Brief:

“The critical insight here is that the central Congo peatlands are probably maintained by rainwater. So, even modest reductions in dry season water-logging, perhaps through rising temperatures and increasing evaporation rates, would mean the whole system moves from a carbon sink to a carbon source.”

In other words, climate change could cause the Congo peatlands to start releasing more carbon into the atmosphere than it is able to absorb.

Forest under threat

Another threat to Congo’s peatlands could come from a potential rise in deforestation for wood and palm oil production in the region, the study notes.

The removal of trees from above peatlands can leave large areas of ground exposed to the sun, which can cause the boggy ground to dry out. This can cause the peatlands to release carbon at a faster rate.

At present, government officials from the DRC have granted logging access to 20% of the forested peatlands. The extent of the logging concession agreements (red outlines) is shown on the chart below, where dark grey indicates peatland and light grey shows other types of land cover.

At least one concession agreement (shown in shaded red) has also been approved for the construction of an oil palm plantation in the Republic of the Congo part of the peatlands, which would take up 4,200km sq of forested peatlands.

Extent of logging concessions (red outlines) and oil palm concessions (shaded red) granted in the Cuvette Centrale. Dark grey shows the location of the Cuvette Centrale peatlands, while light grey shows other types of land cover. Source: Dargie et al. (2018)

Despite these agreements being reached, logging operations are yet to commence in the peatland forests. This is likely to be because the DRC introduced a national ban on logging in 2002, the study notes.

However, the country’s government is currently considering lifting this ban, which would mean logging could be permitted across large areas of the peatland region.

Plans to lift the ban are being driven forward by the French Development Agency (AFD) with financial support from the Norway-led Central African Forests Initiative (CAFI), Lewis says. These groups argue that lifting the ban could aid social development in the region and make it easier to curb illegal and unregulated deforestation.

On top of this, the peatlands could also be affected by plans to construct hydroelectric dams in region, including the Grand Inga hydropower project. Such projects could divert water away from the wetlands, the study notes.

Overall, the peatlands face an immediate risk from deforestation and land-use change and a more long-term threat from climate change, Lewis says:

“The competing threats of direct land-use change and climate change are difficult to compare. The speed with which land can be converted is fast and can quickly kill large areas of swamp forest. But other areas would probably remain unaffected. The speed of climate change is slower than the movement of bulldozers, but could affect the entire peatland.”

Protecting peat

To protect the peatlands in the short term, policymakers should consider introducing new environmental protections to the region, the authors write in their paper:

“Further research, therefore, needs to integrate knowledge from local communities, the natural sciences and social sciences, to develop a more holistic understanding of the Cuvette Centrale peatlands and facilitate local communities and their governments to manage and protect this globally significant region.”

However, protecting the peatlands from the threat of climate change will require a long-term “international effort”, Dargie says:

“With climate change, there is also the added complication that Republic of the Congo and DRC government policies and interventions alone will not be enough to avoid any negative impacts on the Congo Basin peatlands. That will require an international effort to reduce greenhouse gas emissions.”

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