Australia’s bushfires could drive more than 700 animal species to extinction. Check the numbers for yourself



Invertebrates out greatly outnumber mammals everywhere, including in bushfire zones.
Michael Lee, CC BY-NC-ND

Mike Lee, Flinders University

The scale and speed of the current bushfire crisis has caught many people off-guard, including biodiversity scientists. People are scrambling to estimate the long-term effects. It is certain that many animal species will be pushed to the brink of extinction, but how many?

One recent article suggested 20 to 100, but this estimate mostly considers large, well-known species (especially mammals and birds).

A far greater number of smaller creatures such as insects, snails and worms will also be imperilled. They make up the bulk of biodiversity and are the little rivets holding ecosystems together.




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But we have scant data on how many species of small creatures have been wiped out in the fires, and detailed surveys comparing populations before and after the fires will not be forthcoming. So how can we come to grips with this silent catastrophe?

This native bee (Amphylaeus morosus) has been devastated by the bushfires across much of its range. It plays important roles in pollinating plants and as part of the food web, but has no common name, and its plight is so far unheralded.
Reiner Richter https://www.ala.org.au/

Using the information that is available, I calculate that at least 700 animal species have had their populations decimated – and that’s only counting the insects.

This may sound like an implausibly large figure, but the calculation is a simple one. I’ll explain it below, and show you how to make your own extinction estimate with only a few clicks of a calculator.

Using insects to estimate true extinction numbers

More than three-quarters of the known animal species on Earth are insects. To get a handle on the true extent of animal extinctions, insects are a good place to start.

My estimate that 700 insect species are at critical risk involves extrapolating from the information we have about the catastrophic effect of the fires on mammals.

We can work this out using only two numbers: A, how many mammal species are being pushed towards extinction, and B, how many insect species there are for each mammal species.

To get a “best case” estimate, I use the most conservative estimates for A and B below, but jot down your own numbers.

How many mammals are critically affected?

A recent Time article lists four mammal species that will be severely impacted: the long-footed potoroo, the greater glider, the Kangaroo Island dunnart, and the black-tailed dusky antechinus. The eventual number could be much greater (e.g the Hastings River mouse, the silver-headed antechinus), but let’s use this most optimistic (lowest) figure (A = 4).

Make your own estimate of this number A. How many mammal species do you think would be pushed close to extinction by these bushfires?

We can expect that for every mammal species that is severely affected there will be a huge number of insect species that suffer a similar fate. To estimate exactly how many, we need an idea of insect biodiversity, relative to mammals.

How many insect species are out there, for each mammal species?

The world has around 1 million named insect species, and around 5,400 species of land mammals.

So there are at least 185 insect species for every single land mammal species (B = 185). If the current bushfires have burnt enough habitat to devastate 4 mammal species, they have probably taken out around 185 × 4 = 740 insect species in total. Along with many species of other invertebrates such as spiders, snails, and worms.

There are hundreds of insect species for every mammal species.
https://imgbin.com/

For your own value for B, use your preferred estimate for the number of insect species on earth and divide it by 5,400 (the number of land mammal species).

One recent study suggests there are at least 5.5 million species of insects, giving a value of B of around 1,000. But there is reason to suspect the real number could be much greater.




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How do our estimates compare?

My “best case” values of A = 4 and B = 185 indicate at least 740 insect species alone are being imperilled by the bushfires. The total number of animal species impacted is obviously much bigger than insects alone.

Feel free to perform your own calculations. Derive your values for A and B as above. Your estimate for the number of insect species at grave risk of extinction is simply A × B.

Post your estimate and your values for A and B please (and how you got those numbers if you wish) in the Comments section and compare with others. We can then see what the wisdom of the crowd tells us about the likely number of affected species.




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Why simplistic models can still be very useful

The above calculations are a hasty estimate of the magnitude of the current biodiversity crisis, done on the fly (figuratively and literally). Technically speaking, we are using mammals as surrogates or proxies for insects.

To improve these estimates in the near future, we can try to get more exact and realistic estimates of A and B.

Additionally, the model itself is very simplistic and can be refined. For example, if the average insect is more susceptible to fire than the average mammal, our extinction estimates need to be revised upwards.

Also, there might be an unusually high (or low) ratio of insect species compared to mammal species in fire-affected regions. Our model assumes these areas have the global average – whatever that value is!

And most obviously, we need to consider terrestrial life apart from insects – land snails, spiders, worms, and plants too – and add their numbers in our extinction tally.

Nevertheless, even though we know this model gives a huge underestimate, we can still use it to get an absolute lower limit on the magnitude of the unfolding biodiversity crisis.

This “best case” is still very sad. There is a strong argument that these unprecedented bushfires could cause one of biggest extinction events in the modern era. And these infernos will burn for a while longer yet.The Conversation

Mike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

You can leave water out for wildlife without attracting mosquitoes, if you take a few precautions



Leaving water out for wildlife is important during droughts and bushfires but if it’s not changed regularly it can be a breeding ground for mosquitoes.
Roger Smith/Flickr, CC BY-NC

Cameron Webb, University of Sydney

Australia is in for a long, hot summer. The recent bushfires have been devastating for communities and wildlife. Drought is also impacting many regions.

Understandably, people want to leave water out for thirsty birds and animals.

Health authorities generally warn against collecting and storing water in backyards as one measure to protect against mosquito bites and mosquito-borne diseases caused by, for example, dengue and Ross River viruses.




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But it’s possible to leave water out for wildlife – and save water for your garden – without supplying a breeding ground for mosquitoes, if you take a few precautions.

For some mozzies, any water will do

Mosquitoes often look for wetlands and ponds to lay their eggs. But sometimes, anything that holds water – a bucket, bird bath, drain or rainwater tank – will do.

When the immature stages of mosquitoes hatch out of those eggs, they wriggle about in the water for a week or so before emerging to fly off in search of blood.

While there are many mosquitoes found in wetlands and bushland areas, Aedes notoscriptus and Culex quinquefasciatus are the mosquitoes most commonly found in our backyards and have been shown to transmit pathogens that cause mosquito-borne disease.

The Australian backyard mosquito (Aedes notoscriptus) is quick to take advantage of water-filled containers around the home.
Cameron Webb (NSW Health Pathology)

In central and north Queensland, mosquitoes such as Aedes aegypti can bring more serious health threats, such as dengue, to some towns.




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Mosquitoes can also impact our quality of life through bites as well as the nuisance of simply buzzing about our bedrooms and backyards.

So how can you stop mozzies making a home in your backyard?

Empty water containers once a week

Mosquitoes need access to standing water for about a week or so. Reduce the number of water-filled containers available or how long that water is available to mosquitoes.

Emptying a water-filled container once a week will stop the immature mosquitoes from completing their development and emerging as adults.

If you’re leaving water out for pets or wildlife, use smaller volume containers that will allow for easy emptying once a week. You can tip any remaining water into the garden, as mosquito larvae won’t survive if they’re “stranded” on soil.

For larger or heavier items, such as bird baths, flushing them out once a week with the hose will knock out most of the wrigglers and stop the mosquitoes completing their life cycle.

Make sure garden water doesn’t slosh about

Be careful with self-watering planter boxes. These often have a reservoir of water in their base and, while it may seem like a water-wise idea, these can turn into tiny mozzie hotels!

A simple trick to keep water available to plants, but not mosquitoes, is to fill your potted plant saucers with sand. The sand traps and stores some moisture but there is no water sloshing about for mosquitoes.

If you’re collecting water from showers, baths, or washing machines (commonly known as grey water), use it immediately on the garden, don’t store it outside in buckets or other containers.




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Gutters, ponds, tanks and pools

Make sure your roof gutters and drains are free of leaves and other debris that will trap water and provide opportunities for mosquitoes.

Ensure rainwater tanks (and other large water-storage containers) are appropriately screened to prevent access by mosquitoes.

Rainwater tanks can be a useful way to conserve water in our cities but they can also be a source of mosquitoes.
Cameron Webb (NSW Health Pathology)

A well maintained swimming pool won’t be a source of mosquitoes. But if it’s turning “green”, through neglect and not intent, it may become a problem. Mosquitoes don’t like the chlorine or salt treatments typically used for swimming pools but when there is a build up of leaves and other detritus, as well as algae, the mosquitoes will move in.




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For backyard ponds, introducing native fish can help keep mosquito numbers down.

But if you want your pond to be a home for frogs, avoid fish as they may eat the tadpoles. Instead, try to encourage other wildlife that may help keep mosquito numbers down by creating habitats for spiders and other predatory insects, reptiles, frogs, birds, and bats.

Avoiding excessive use of insecticides around the backyard will help encourage and protect that wildlife too.

Mozzies can still come

There isn’t much that can be done about those mosquitoes flying in from over the back fences from local bushland or wetland areas.

Mosquitoes are generally most active at dusk and dawn so keep that in mind when planning time outdoors. But when mosquito populations are peaking, they’ll be active almost all day long.

Applying an insect repellent can be a safe and effective way to stop those bites.




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Covering up with long pants, long-sleeved shirt and shoes will provide a physical barrier to mosquitoes. If you’re spending a lot of time outdoors, perhaps even consider treating your clothing with insecticide to add that extra little bit of protection.

Make sure insect screens are installed, and in good condition, on windows and doors. Mosquitoes outdoors can be bad; you don’t want them inside as well.The Conversation

Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia’s threatened birds declined by 59% over the past 30 years


Elisa Bayraktarov, The University of Queensland and Jaana Dielenberg, The University of Queensland

Australia’s threatened birds declined by nearly 60% on average over 30 years, according to new research that reveals the true impact on native wildlife of habitat loss, introduced pests, and other human-caused pressures.

Alarmingly, migratory shorebirds have declined by 72%. Many of these species inhabit our mudflats and coasts on their migration from Siberia, Alaska or China each year.




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These concerning figures are revealed in our world-first Threatened Bird Index. The index, now updated with its second year of data, combines over 400,000 surveys at more than 17,000 locations.

It’s hoped the results will shed light on where conservation efforts are having success, and where more work must be done.

Bringing conservation efforts together

The index found a 59% fall in Australia’s threatened and near threatened bird populations between 1985 and 2016.

Migratory shorebirds in South Australia and New South Wales have been worst hit, losing 82% and 88% of their populations, respectively. In contrast, shorebirds in the Northern Territory have increased by 147% since 1985, potentially due to the safe roosting habitat at Darwin Harbour where human access to the site is restricted.

Habitat loss and pest species (particularly feral cats) are the most common reasons for these dramatic population declines.

Many of Australia’s threatened species are monitored by various organisations across the country. In the past there has never been a way to combine and analyse all of this evidence in one place.




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The Threatened Species Recovery Hub created the index to bring this information together. It combines 17,328 monitoring “time series” for threatened and near threatened bird species and subspecies. This means going back to the same sites in different years and using the same monitoring method, so results over time can be compared.

Over the past year the amount of data underpinning the index has grown considerably and now includes more than 400,000 surveys, across 43 monitoring programs on 65 bird species and subspecies, increasing our confidence in these alarming trends.

Threatened species like the Gilbert’s Whistler, Chestnut quail-thrush and Swift parrot are all on the decline.
Glenn Ehmke, BirdLife Australia, Author provided

About one-third of Australia’s threatened and near threatened birds are in the index but that proportion is expected to grow. As more quality data becomes available, the index will get more powerful, meaningful and representative. For the first time Australia will be able to tell how our threatened species are going overall, and which groups are doing better or worse, which is vital to identifying which groups and regions most need help.

Finding the trends

Trends can be calculated for any grouping with at least three species. A grouping might include all threatened species in a state or territory, all woodland birds or all migratory shorebirds.

The 59% average decrease in threatened bird relative abundance over the last 30 years is very similar to the global wildlife trends reported by the 2018 Living Planet Report. Between 1970 and 2014, global average mammal, fish, bird, amphibian and reptile populations fell by 60%.

One valuable feature of the Threatened Species Index is a visualisation tool which allows anyone to explore the wealth of data, and to look at trends for states and territories.

For instance, in Victoria by 2002 threatened birds had dropped to a bit more than half of their numbers in 1985 on average (60%), but they have remained fairly constant since then.

We can also look at different bird groups. Threatened migratory shorebirds have had the largest declines, with their numbers down by more than 72% since 1985. Threatened terrestrial birds, on the other hand, have decreased in relative abundance by about 51% between 2000 and the year 2016, and show a relatively stable trend since 2006.

Eastern Great Egret, and Bar-tailed Godwit. Pictures kindly provided by Glenn Ehmke, BirdLife Australia.

Making the index better

The index is being expanded to reveal trends in species other than birds. Monitoring data on threatened mammals and threatened plants is being assembled. Trends for these groups will be released in 2020, providing new insights into how a broader range of Australia’s threatened species are faring.

This research is led by the University of Queensland in close partnership with BirdLife Australia, and more than 40 partners from research, government, and non-government organisations. Collaboration on such a scale is unprecedented, and provides extremely detailed information.




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The index team are continuing to work with monitoring organisations across Australia to expand the amount of sites, and the number of species included in the index. We applaud the dedicated researchers, managers and citizen scientists from every corner of the country who have been assembling this data for the nation.

We’d also like to hear from community groups, consultants and other groups that have been monitoring threatened or near-threatened species, collecting data at the same site with the same method in multiple years.

The Threatened Species Index represents more than just data. Over time it will give us a window into the results of our collective conservation efforts.


This article also received input from James O’Connor (BirdLife Australia) and Hugh Possingham (The Nature Conservancy).The Conversation

Elisa Bayraktarov, Postdoctoral Research Fellow in Conservation Biology, The University of Queensland and Jaana Dielenberg, Science Communication Manager, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Most native bird species are losing their homes, even the ones you see every day



Eastern-yellow robin. Some 60 per cent of the native birds of south-east mainland Australia have lost more than half of their natural habitat.
Graham Winterflood/Wikimedia Commons

Jeremy Simmonds, The University of Queensland; Alvaro Salazar, The University of Queensland; James Watson, The University of Queensland, and Martine Maron, The University of Queensland

Across parts of Australia, vast areas of native vegetation have been cleared and replaced by our cities, farms and infrastructure. When native vegetation is removed, the habitat and resources that it provides for native wildlife are invariably lost.

Our environmental laws and most conservation efforts tend to focus on what this loss means for species that are threatened with extinction. This emphasis is understandable – the loss of the last individual of a species is profoundly sad and can be ecologically devastating.




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But what about the numerous other species also affected by habitat loss, that have not yet become rare enough to be listed as endangered? These animals and plants — variously described as “common” or of “least concern” — are having their habitat chipped away. This loss usually escapes our attention.

These common species have intrinsic ecological value. But they also provide important opportunities for people to connect with nature – experiences that are under threat.

A chain used for land clearing is dragged over a pile of burning wood at a Queensland property.
Dan Peled/AAP

The “loss index”: tracking the destruction

We developed a measure called the loss index to communicate how habitat loss affects multiple Australian bird species. Our measure showed that across Victoria, and into South Australia and New South Wales, more than 60% of 262 native birds have each lost more than half of their original natural habitat. The vast majority of these species are not formally recognised as being threatened with extinction.

It is a similar story in the Brigalow Belt of central New South Wales and Queensland. The picture is brighter in the northern savannas across the top of Australia, where large tracts of native vegetation remain – notwithstanding pervasive threats such as inappropriate fire regimes.




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We also found that in some areas, such as Southeast Queensland and the Wet Tropics region of north Queensland, the removal of a single hectare of forest habitat can affect up to 180 different species. In other words, small amounts of loss can affect large numbers of (mostly common) species.

Our index allowed us to compare how different groups of birds are impacted by habitat loss. Australia’s iconic parrots have been hit hard by habitat loss, because many of these birds occur in the places where we live and grow our food. Birds of prey such as eagles and owls have, as a group, been less affected. This is because many of these birds occur widely across Australia’s less developed arid interior.

This map shows the number of bird species affected by habitat loss in any region. Grey zones indicate parts of Australia where habitat loss has not occurred. Blue zones have up to 90 species affected by habitat loss, yellow is up to 120 species affected, while the highest category, red, is up to 187 species affected.
Conservation Biology

Habitat loss means far fewer birds

Our study shows many species have lost lots of habitat in certain parts of Australia. We know habitat loss is a major driver of population declines and freefalling numbers of animals globally. A measure of vertebrate population trends — the Living Planet Index — reveals that populations of more than 4,000 vertebrate species around the world are on average less than half of what they were in 1970.

In Australia, the trend is no different. Populations of our threatened birds declined by an average of 52% between 1985 and 2015. Alarmingly, populations for many common Australian birds are also trending downwards, and habitat loss is a major cause. Along Australia’s heavily populated east coast, population declines have been noted for many common species including rainbow bee-eater, double-barred finch, and pale-headed rosella.

Decling common species – rainbow bee-eater (left); double-barred finch (top right); pale-headed rosella (bottom right)
Jim Bendon, G. Winterflood, Aviceda



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This is a major problem for ecosystem health. Common species tend to be more numerous and so perform many roles that we depend on. Our parrots, pigeons, honeyeaters, robins, and many others help pollinate flowers, spread seeds, and keep pest insects in check. In both Europe and Australia, declines in common species have been linked to a reduction in the provision of these vital ecosystem services.

Common species are also the ones that we most associate with. Because they are more abundant and familiar, these animals provide important opportunities for people to connect with nature. Think of the simple pleasure of seeing a colourful robin atop a rural fence post, or a vibrant parrot dashing above the treetops of a suburban creek. The decline of common species may contribute to diminished opportunities for us to interact with nature, leading to an “extinction of experience”, with associated negative implications for our health and well-being.

We mustn’t wait until it’s too late

Our study aims to put the spotlight on common species. They are crucially important, and yet the erosion of their habitat gets little focus. Conserving them now is sensible. Waiting until they have declined before we act will be costly.

These species need more formal recognition and protection in conservation and environmental regulation. For example, greater attention on common species, and the role they play in ecosystem health, should be given in the assessment of new infrastructure developments under Australia’s federal environment laws (formally known as the Environment Protection and Biodiversity Conservation Act 1999).

We should be acting now to conserve common species before they slide towards endangerment. Without dedicated attention, we risk these species declining before our eyes, without us even noticing.The Conversation

Jeremy Simmonds, Postdoctoral Research Fellow in Conservation Science, The University of Queensland; Alvaro Salazar, Postdoctoral Research Fellow, The University of Queensland; James Watson, Professor, The University of Queensland, and Martine Maron, ARC Future Fellow and Professor of Environmental Management, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hot as shell: birds in cooler climates lay darker eggs to keep their embryos warm


The colour and brightness of birds’ eggs plays a key role in keeping them at the right temperature.
Anne Kitzman / Shutterstock

Phill Cassey, University of Adelaide and Daniel Hanley, Long Island University Post

Birds lay eggs with a huge variety of colours and patterns, from immaculate white to a range of blue-greens and reddish browns.

The need to conceal eggs from predators is one factor that gives rise to all kinds of camouflaged and hard-to-spot appearances.

Yet our research, published today in Nature Ecology & Evolution, shows that climate is even more important.

Dark colours play a crucial role in regulating temperatures in many biological systems. This is particularly common for animals like reptiles, which rely on environmental sources of heat to keep themselves warm.




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Darker colours absorb more heat from sunlight, and animals with these colours are more commonly found in colder climates with less sunlight. This broad pattern is known as Bogert’s rule.

Birds’ eggs are useful for studying this pattern because the developing embryo can only survive in a narrow range of temperatures. But eggs cannot regulate their own temperature and, in most cases, the parent does it by sitting atop the clutch of eggs.

In colder environments, where the risk of predators is lower and the risk of chilling in cold temperatures is greater, parents spend less time away from the nest.

We predicted that if eggshell colour does play an important role in regulating the temperature of the embryo, birds living in colder environments should have darker eggs.

The average colour of eggshells in different areas around the world.
Wisocki et al. 2019 ‘The global distribution of avian eggshell colours suggests a thermoregulatory benefit of darker pigmentation’, Nature Ecology & Evolution, Author provided

To test the prediction, we measured eggshell brightness and colour for 634 species of birds. That’s more than 5% of all bird species, representing 36 of the 40 large groups of species called orders.

We mapped these within each species’ breeding range and found that eggs in the coldest environments (those with the least sunlight) were significantly darker. This was true for all nest types.

We also conducted experiments using domestic chicken eggs to confirm that darker eggshells heated up more rapidly and maintained their incubation temperatures for longer than white eggshells.




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Our results show that darker eggshells are found in places with less sunlight and lower temperatures, and that these darker colours may help keep the developing embryo warm.

How future climate change will affect eggshell appearance, as well as the timing of reproduction and incubation behaviour, will be an important and fruitful avenue for future research.The Conversation

Phill Cassey, Assoc Prof in Invasion Biogeography and Biosecurity, University of Adelaide and Daniel Hanley, Assistant Professor, Long Island University Post

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How barnacle geese adjust their migratory habits in the face of climate change



Shutterstock

Thomas Oudman, University of St Andrews

The climate is changing at an unprecedented rate, and so are the environments of many plant and animal species. Populations die out in places that become intolerable, and thrive in other places that have become more benign.

But for many species, population growth in new places does not keep up with the decline elsewhere. For some species, such as polar bears, such benign places do not even exist. And even if they do, species still face a significant problem: they need to find them.

This problem is perhaps more serious for migratory animals, which have to adjust to not one, but several changing environments that they visit throughout the year. Even after finding a new habitat one year, they must find it again the next, and every year after that. How on earth do these creatures know where to go?

This question is not trivial: many migratory populations are declining. What seems to be killing them is their inability to adjust to multiple changing habitats at once. The problem might be that it is hard for them to learn new migratory habits.

Geese lead the way

But a few migratory species are thriving. Among them are barnacle geese, a small-sized goose that winters in Europe and traditionally breeds on the Arctic tundras of Siberia, Svalbard and Greenland. So, how are they doing so well?

The barnacle goose faced extinction in the 1950s.
Shutterstock

We barely know the exact routes of many migratory species, let alone how these have changed over time. But here, barnacle geese are the exception. Ever since their near extinction in the 1950s, when fewer than 500 geese were left, scientists have been monitoring their numbers. The geese were observed in their wintering area at the Solway Firth, between Scotland and England, all along the Norwegian coast during spring migration and up to Svalbard.

Each spring from the 1970s onwards, researchers went to Helgeland on Norway’s west coast to observe the geese arriving from the UK to fill their bellies on grass. These fat reserves are essential to complete the second part of their journey north to Svalbard, where they breed.

In the early 1990s, bird researchers discovered a handful of barnacle geese in Vesterålen, 350km to the north-west of Helgeland, while they were counting pink-footed geese – another vulnerable goose population. Since then, the number of barnacle geese in Vesterålen in spring has been increasing steadily.

From the 2000s onwards, goose observers at the traditional feeding site in Helgeland started to see numbers go down. Currently, the majority of the whole population (now 40,000 birds strong) stops off in Vesterålen.

Rapid adjustments? Certainly. The number of geese in Vesterålen in spring has actually grown faster than can be explained by the birth rate alone, meaning that what we’re seeing is not just “the survival of the fittest”. In addition, many individual geese must have switched to feeding in Vesterålen later in life.

Barnacle geese calling.
Juha Saari/Xeno-Canto, CC BY-SA1.4 MB (download)

Along with counting geese, international research groups have been catching geese in the breeding areas on Svalbard since the 1960s, fitting juvenile geese with plastic leg rings with letter codes. This allowed goose observers along the Norwegian coast to actually know which bird they were looking at, and even how old it was.

Since 2000, these observers have gathered enough observations of ringed barnacle geese each year to allow proper calculations. This has enabled us to show that geese are indeed switching to Vesterålen in big numbers. In addition, the probability for individual geese to move to Vesterålen has been increasing, and young birds are far more likely to switch than older ones.

Adapting to climate change

So are these changes a response to climate change? We analysed the grass growth during the feeding period at both locations, which we could estimate from daily temperature and sunshine levels. The start of grass growth in spring has advanced more than three weeks since the 1970s, leading to a strong increase in grass availability during the goose staging period in spring at both locations. But availability is not all that counts.

Barnacle geese arrive in Norway at the end of April. In the 1970s, the snow usually had just melted at that time, and the first grass shoots were coming up. In recent years, the grass was already long when the geese arrived, and contained more cellulose. This is much more difficult for geese to digest than young grass, resulting in a lower rate of fat storage.

Vesterålen is further north, and spring starts much later than in Helgeland. This means that due to climate warming, the annual timing of grass growth in Vesterålen now is how it used to be in Helgeland. Fresh new grass now is just emerging in Vesterålen when the geese arrive, enabling the geese to gain weight fast. So yes, the switch makes sense.

Does that mean that the geese know that the new place is better? Not necessarily. Most of the switchers are young birds, which do not have much experience. Instead, we think that they follow experienced birds to Vesterålen, perhaps after they have arrived in Helgeland to find there is not enough food to go around. Geese operate in families, staying close to their long-term partners and relatives. They might exchange more information than we know.

It’s the group travelling that does the trick for geese, allowing them to profit from the discoveries of others. The question that remains is why other bird species have not evolved in the same way. Perhaps geese have always lived in a more dynamic environment than other migratory species.

Think of shorebirds, which have been dependent on the same shorelines and inter-tidal areas for thousands of years. For them, the current rate of climate change might be something they have not evolved to deal with. Perhaps we are creating a world in which all birds would be better off acting like geese.The Conversation

Thomas Oudman, Postdoctoral Researcher, School of Biology, University of St Andrews

This article is republished from The Conversation under a Creative Commons license. Read the original article.