Fences have big effects on land and wildlife around the world that are rarely measured



Australia’s dingo fences, built to protect livestock from wild dogs, stretch for thousands of kilometers.
Marian Deschain/Wikimedia, CC BY-SA

Alex McInturff, University of California Santa Barbara; Christine Wilkinson, University of California, Berkeley, and Wenjing Xu, University of California, Berkeley

What is the most common form of human infrastructure in the world? It may well be the fence. Recent estimates suggest that the total length of all fencing around the globe is 10 times greater than the total length of roads. If our planet’s fences were stretched end to end, they would likely bridge the distance from Earth to the Sun multiple times.

On every continent, from cities to rural areas and from ancient to modern times, humans have built fences. But we know almost nothing about their ecological effects. Border fences are often in the news, but other fences are so ubiquitous that they disappear into the landscape, becoming scenery rather than subject.

In a recently published study, our team sought to change this situation by offering a set of findings, frameworks and questions that can form the basis of a new discipline: fence ecology. By compiling studies from ecosystems around the world, our research shows that fences produce a complex range of ecological effects.

Some of them influence small-scale processes like the building of spider webs. Others have much broader effects, such as hastening the collapse of Kenya’s Mara ecosystem. Our findings reveal a world that has been utterly reorganized by a rapidly growing latticework of fences.

Conservationists and scientists have raised concerns about the ecological effects of the U.S.-Mexico border wall, most of which is essentially a fence.

Connecting the dots

If fences seem like an odd thing for ecologists to study, consider that until recently no one thought much about how roads affected the places around them. Then, in a burst of research in the 1990s, scientists showed that roads – which also have been part of human civilization for millennia – had narrow footprints but produced enormous environmental effects.

For example, roads can destroy or fragment habitats that wild species rely on to survive. They also can promote air and water pollution and vehicle collisions with wildlife. This work generated a new scientific discipline, road ecology, that offers unique insights into the startling extent of humanity’s reach.

Our research team became interested in fences by watching animals. In California, Kenya, China and Mongolia, we had all observed animals behaving oddly around fences – gazelles taking long detours around them, for example, or predators following “highways” along fence lines.

We reviewed a large body of academic literature looking for explanations. There were many studies of individual species, but each of them told us only a little on its own. Research had not yet connected the dots between many disparate findings. By linking all these studies together, we uncovered important new discoveries about our fenced world.

Vintage ad for barbed wire.
Early advertisement for barbed wire fencing, 1880-1889. The advent of barbed wire dramatically changed ranching and land use in the American West by ending the open range system.
Kansas Historical Society, CC BY-ND

Remaking ecosystems

Perhaps the most striking pattern we found was that fences rarely are unambiguously good or bad for an ecosystem. Instead, they have myriad ecological effects that produce winners and losers, helping to dictate the rules of the ecosystems where they occur.

Even “good” fences that are designed to protect threatened species or restore sensitive habitats can still fragment and isolate ecosystems. For example, fences constructed in Botswana to prevent disease transmission between wildlife and livestock have stopped migrating wildebeests in their tracks, producing haunting images of injured and dead animals strewn along fencelines.

Enclosing an area to protect one species may injure or kill others, or create entry pathways for invasive species.

One finding that we believe is critical is that for every winner, fences typically produce multiple losers. As a result, they can create ecological “no man’s lands” where only species and ecosystems with a narrow range of traits can survive and thrive.

Altering regions and continents

Examples from around the world demonstrate fences’ powerful and often unintended consequences. The U.S.-Mexico border wall – most of which fits our definition of a fence – has genetically isolated populations of large mammals such as bighorn sheep, leading to population declines and genetic isolation. It has even had surprising effects on birds, like ferruginous pygmy owls, that fly low to the ground.

Australia’s dingo fences, built to protect livestock from the nation’s iconic canines, are among the world’s longest man-made structures, stretching thousands of kilometers each. These fences have started ecological chain reactions called trophic cascades that have affected an entire continent’s ecology.

The absence of dingoes, a top predator, from one side of the fence means that populations of prey species like kangaroos can explode, causing categorical shifts in plant composition and even depleting the soil of nutrients. On either side of the fence there now are two distinct “ecological universes.”

Our review shows that fences affect ecosystems at every scale, leading to cascades of change that may, in the worst cases, culminate in what some conservation biologists have described as total “ecological meltdown.” But this peril often is overlooked.

Map showing the density of fencing in the western U.S.
The authors assembled a conservative data set of potential fence lines across the U.S. West. They calculated the nearest distance to any given fence to be less than 31 miles (50 kilometers), with a mean of about 2 miles (3.1 kilometers).
McInturff et al,. 2020, CC BY-ND

To demonstrate this point, we looked more closely at the western U.S., which is known for huge open spaces but also is the homeland of barbed wire fencing. Our analysis shows that vast areas viewed by researchers as relatively untrodden by the human footprint are silently entangled in dense networks of fences.

Do less harm

Fences clearly are here to stay. As fence ecology develops into a discipline, its practitioners should consider the complex roles fences play in human social, economic and political systems. Even now, however, there is enough evidence to identify actions that could reduce their harmful impacts.

There are many ways to change fence design and construction without affecting their functionality. For example, in Wyoming and Montana, federal land managers have experimented with wildlife-friendly designs that allow species like pronghorn antelope to pass through fences with fewer obstacles and injuries. This kind of modification shows great promise for wildlife and may produce broader ecological benefits.

Another option is aligning fences along natural ecological boundaries, like watercourses or topographical features. This approach can help minimize their effects on ecosystems at low cost. And land agencies or nonprofit organizations could offer incentives for land owners to remove fences that are derelict and no longer serve a purpose.

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Nonetheless, once a fence is built its effects are long lasting. Even after removal, “ghost fences” can live on, with species continuing to behave as if a fence were still present for generations.

Knowing this, we believe that policymakers and landowners should be more cautious about installing fences in the first place. Instead of considering only a fence’s short-term purpose and the landscape nearby, we would like to see people view a new fence as yet another permanent link in a chain encircling the planet many times over.The Conversation

Alex McInturff, Postdoctoral Researcher, University of California Santa Barbara; Christine Wilkinson, Ph.D. Candidate in Environmental Science, Policy and Management, University of California, Berkeley, and Wenjing Xu, PhD Candidate in Environmental Science, Policy and Management, University of California, Berkeley

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

Pacific killer whales are dying — new research shows why



A female killer whale leaps from the water in Puget Sound near Seattle.
(AP Photo/Elaine Thompson)

Stephen Raverty, University of British Columbia and Joseph K. Gaydos, University of California, Davis

Killer whales are icons of the northeastern Pacific Ocean. They are intimately associated with the region’s natural history and First Nations communities. They are apex predators, with females living as long as 100 years old, and recognized a sentinels of ecosystem health — and some populations are currently threatened with extinction.

There are three major types of killer whales in the region: the “resident” populations that feed mainly on salmon, the “transients” that prey on other marine mammals like seals and sea lions, and the “offshores” that transit along the continental shelf, eating fish and sharks.

In the 1990s, an abrupt decline in the fish-eating southern resident population dropped to 75 whales from 98, prompting both Canada and the United States to list them as endangered.

A dead killer whale lies on her side in shallow water.
Emaciated female killer whale from Hawaii.
(NOAA/NMFS/PIRO), CC BY

Since then, southern resident killer whales, whose range extends from the waters off the southeast Alaska and the coast of British Columbia to California, have not recovered — only 74 remain today. Because killer whale strandings are rare, scientists have been uncertain about the causes of killer whale mortality and how additional deaths might be prevented in the future.

As a pathologist and wildlife veterinarian, and with the help of countless biologists and veterinarians, we have carried out in-depth investigations into why killer whales in this region strand and died. If we don’t know what is causing killer whale deaths, we are not able to prevent the ones that are human-caused.

We can do better

Human activities have been implicated in the decline and lack of recovery of the southern resident killer whale population, including ship noise and strikes, contaminants, reduced prey abundance and past capture of these animals for aquariums.

Only three per cent and 20 per cent of the northern and southern resident killer whales, respectively, that died between 1925 and 2011 were even found and available for a post-mortem exam. And in most cases, only cursory or incomplete post-mortem exams can be done, generating a limited amount of information.

To figure out why these killer whales are dying — and what it means for the health of individual animals and the population as a whole — we reviewed the post-mortem records of 53 animals that became stranded in the eastern Pacific Ocean and Hawaii between 2004 and 2013. We identified the cause of death in 22 animals, and gained important insight from nine other animals where the cause of death could not be determined.

Human-caused injuries were found in nearly every age group of whales, including adults, sub-adults and calves. Some had ingested fishing hooks, but evidence of blunt-force trauma, consistent with ship and propeller strikes, was more common.

A dead killer whale lies on a beach
The 18-year-old male southern resident killer whale, J34, stranded near Sechelt, B.C., on Dec. 21, 2016. Post-mortem examination suggested he died from trauma consistent with vessel strike.
(Paul Cottrell/Fisheries and Oceans Canada), Author provided

This is the first study to document the lesions and forensic evidence of lethal trauma from ship and propeller strikes.

In recent years governments have focused on limiting vessel noise and disturbance. This study reinforces the need for this, showing that in addition to noise and disturbance, vessel strikes are an important cause of death in killer whales.

Direct human impact

We also developed a body condition index to evaluate the animals’ nutritional health — were they eating enough salmon, for example — to see what role food might play in the sickness and death of stranded animals. Observations of free-ranging killer whales from boats and by unmanned aerial drones have documented sub-optimal body condition or generalized emaciation in many southern resident killer whales.

In this study, we found that longer and therefore older animals tend to have thicker blubber. Our study also found that those animals that died from blunt-force trauma had a better body condition — they were in good health before death. Those that died from infections or nutritional causes were more likely to be in worse body condition.

This new body condition index can help scientists better understand the health of killer whales, and gives us a tool to evaluate their health regardless of their age, reproductive status and health condition.

Our team, working with numerous collaborators including the National Marine Mammal Foundation, is building a health database of the killer whales living in the northeastern Pacific Ocean so that their health can be tracked over time. This centralized database will let stranding response programs, regional and national government agencies and First Nations communities collaborate with field biologists, research scientists and veterinarians.

Ultimately, the information about the health of these killer whales must be conveyed to the public and policy-makers to ensure that the appropriate legislation is enacted to reverse the downward trend in the health and survival of these killer whales. We should now be able to assess future efforts and gain a better understanding of the impact of ongoing human activities, such as fishing, boating and shipping.The Conversation

Stephen Raverty, Adjunct professor, Veterinary Pathology, University of British Columbia and Joseph K. Gaydos, Wildlife Veterinarian and Science Director, The SeaDoc Society, University of California, Davis

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

Daytime sightings of elusive aardvarks hint at troubled times in the Kalahari



Disappearance of aardvarks from dry ecosystems could have devastating consequences for the many other animals that rely on their burrows.
Kelsey Green

Robyn Hetem, University of the Witwatersrand and Nora Marie Weyer, University of the Witwatersrand

Aardvarks are notoriously elusive, nocturnal mammals. They generally hide in their underground burrows during the day and emerge at night to feed exclusively on ants and termites. Aardvarks are widespread throughout most habitats of Africa south of the Sahara, except deserts. But their actual numbers are not known because they’re so elusive.

Aardvarks top the bucket list of many wildlife enthusiasts, but few have been fortunate enough to see them – until recently. Daytime sightings of aardvarks are becoming more common in the drier parts of southern Africa. But seeing them in the daytime does not bode well because it indicates they might not be finding enough food.

To understand how aardvarks cope with hot and dry conditions, we studied them in the Kalahari, one of the hottest and driest savannah regions in southern Africa in which aardvarks occur. Our study took place at Tswalu, a private reserve in South Africa that supports research through the Tswalu Foundation. We equipped wild, free-living aardvarks with biologgers (minicomputers) that remotely and continuously recorded their body temperature (an indicator of well-being in large mammals), and their activity. Each aardvark also received a radio-tracking device, allowing us to locate them regularly. Tracking the aardvarks provided clues on how they changed their behaviour in relation to environmental stressors in the different seasons and years of our three-year study.

Our study found that in drought periods, aardvarks struggled to find food. It was difficult for them to maintain their energy balance and stay warm during the cool night, so they shifted their active time to the day. Some died from starvation. Given the aardvark’s importance to ecosystems, these findings are a concern.

Comparison of Aardvarks at night and day
Aardvarks usually emerge from their burrows at night (left), but during drought periods, they are increasingly seen during daytime (right).
N. Weyer

Aardvarks are important ecosystem engineers

No other mammal in Africa digs as many large burrows as the aardvark. Dozens of mammals, birds and reptiles use aardvark burrows as shelter from extreme heat and cold, protection from predators, or a place to raise their young. In many of South Africa’s conservation areas, temperatures have already risen by 2℃ over the past 50 years. Further warming by 4-6℃ by the end of the century has been projected.

With deserts and drylands expanding across much of Africa, climate change might threaten the aardvark itself as well as the many animals reliant on aardvark burrows as a cool shelter from rising temperatures.

During typical years, aardvarks were active at night and were able to regulate their body temperature between 35-37℃.

Aardvark active at night during non-drought times
Aardvark active at night during non-drought times.
adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637

However, this pattern changed during two severe summer droughts that occurred in the Kalahari during our study. During the droughts, aardvarks shifted their activity to the daytime and their body temperature plummeted below 30°C.

Using remotely-sensed vegetation data recorded by NASA satellites and our own camera trap footage and logger data, we showed that these dramatic changes in body temperature and activity of aardvarks were related to the availability of grass, on which their ant and termite prey rely. When grass was scarce during droughts, the ant and termite prey became inaccessible to aardvarks, preventing them from meeting their daily energy requirements. As their body reserves declined, aardvarks were unable to sustain the energy costs of maintaining warm and stable body temperatures and shifted their activity to the warmer daytime.

Aardvark active in the daytime during drought
Aardvark active in the daytime during drought.
adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637

Shifting activity to the warmer daytime while food is scarce can save energy that would otherwise be spent on staying warm during cold nights. But, for our aardvarks, even these energy savings were insufficient during drought, when the ground was bare and the ant and termite prey inaccessible. As a result, seven of our twelve study aardvarks and many others died, presumably from starvation.

A bleak future for aardvarks in a hotter and drier world

On the Red List of Species of the International Union for Conservation of Nature, aardvarks are currently categorised as a species of “Least Concern”. However, we consider aardvarks to be threatened in the drier parts of their distribution in Africa, such as the Kalahari, where climate change brings about droughts. Disappearance of aardvarks from these ecosystems could have devastating consequences for the many other animals that rely on the aardvarks’ burrows.

We hope that our findings will raise further awareness about the consequences of climate change and inform future wildlife conservation and management decisions. Such steps might include assessments of the actual population status of aardvarks across Africa, or mitigation measures to preserve species that depend on burrows for refuge in regions where aardvarks might go locally extinct. More extensive measures, like water-wise reserve management, increasing sizes and connectivity of nature reserves in semi-arid regions, and reducing emissions to mitigate climate change, are just as urgent.

Finally, any solution to the plight of climate change on free-living animals requires a better understanding of their capacities to cope with drought. Therefore, many more long-term comprehensive studies are needed on the physiology and behaviour of the vulnerable animals living in hot, arid regions of the world.

Nora Marie Weyer’s disclosure statement has been updated.The Conversation

Robyn Hetem, Senior Lecturer, University of the Witwatersrand and Nora Marie Weyer, PhD – Wildlife Conservation Physiology, University of the Witwatersrand

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

Humans are changing fire patterns, and it’s threatening 4,403 species with extinction



The Leadbeater’s possum, one of thousands of species threatened by changing fire regimes.
Shutterstock

Luke Kelly, University of Melbourne; Annabel Smith, The University of Queensland; Katherine Giljohann, University of Melbourne, and Michael Clarke, La Trobe University

Last summer, many Australians were shocked to see fires sweep through the wet tropical rainforests of Queensland, where large and severe fires are almost unheard of. This is just one example of how human activities are changing fire patterns around the world, with huge consequences for wildlife.

In a major new paper published in Science, we reveal how changes in fire activity threaten more than 4,400 species across the globe with extinction. This includes 19% of birds, 16% of mammals, 17% of dragonflies and 19% of legumes that are classified as critically endangered, endangered or vulnerable.




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But, we also highlight the emerging ways we can help promote biodiversity and stop extinctions in this new era of fire. It starts with understanding what’s causing these changes and what we can do to promote the “right” kind of fire.

How is fire activity changing?

Recent fires have burned ecosystems where wildfire has historically been rare or absent, from the tropical forests of Queensland, Southeast Asia and South America to the tundra of the Arctic Circle.

Exceptionally large and severe fires have also been observed in areas with a long history of fire. For example, the 12.6 million hectares that burnt in eastern Australia during last summer’s devastating bushfires was unprecedented in scale.

The post-fire landscape in Flinders Chase National Park, Kangaroo Island, three months after an extremely large and severe bushfire last summer.
Luke Kelly

This extreme event came at a time when fire seasons are getting longer, with more extreme wildfires predicted in forests and shrublands in Australia, southern Europe and western United States.

But fire activity isn’t increasing everywhere. Grasslands in countries such as Brazil, Tanzania, and the United States have had fire activity reduced.

Extinction risk in a fiery world

Fire enables many plants to complete their life cycles, creates habitats for a wide range of animals and maintains a diversity of ecosystems. Many species are adapted to particular patterns of fire, such as banksias — plants that release seeds into the resource-rich ash covering the ground after fire.

But changing how often fires occur and in what seasons can harm populations of species like these, and transform the ecosystems they rely on.

We reviewed data from the International Union for Conservation of Nature (IUCN) and found that of the 29,304 land-based and freshwater species listed as threatened, modified fire regimes are a threat to more than 4,403.

Most are categorised as threatened by an increase in fire frequency or intensity.

For example, the endangered mallee emu-wren in semi-arid Australia is confined to isolated patches of habitat, which makes them vulnerable to large bushfires that can destroy entire local populations.

Likewise, the Kangaroo Island dunnart was listed as critically endangered before it lost 95% of its habitat in the devastating 2019-2020 bushfires.

Large bushfires threaten many birds, such as the mallee emu-wren.
Ron Knight/Wikimedia, CC BY

However, some species and ecosystems are threatened when fire doesn’t occur. Frequent fires are an important part of African savanna ecosystems and less fire activity can lead to shrub encroachment. This can displace wild herbivores such as wildebeest that prefer open areas.

How humans change fire regimes

There are three main ways humans are transforming fire activity: global climate change, land-use and the introduction of pest species.

Global climate change modifies fire regimes by changing fuels such as dry vegetation, ignitions such as lightning, and creating more extreme fire weather.

What’s more, climate-induced fires can occur before the dominant tree species are old enough to produce seed, and this is reshaping forests in Australia, Canada and the United States.

Humans also alter fire regimes through farming, forestry, urbanisation and by intentionally starting or suppressing fires.

Introduced species can also change fire activity and ecosystems. For example, in savanna landscapes of Northern Australia, invasive gamba grass increases flammability and fire frequency. And invasive animals, such as red foxes and feral cats, prey on native animals exposed in recently burnt areas.




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Importantly, cultural, social and economic changes underpin these drivers. In Australia, the displacement of Indigenous peoples and their nuanced and purposeful use of fire has been linked with extinctions of mammals and is transforming vegetation.

We need bolder conservation strategies

A suite of emerging actions — some established but receiving increasing attention, others new — could help us navigate this new fire era and save species from extinction. They include:

In Africa, reintroducing grazing animals such as rhinoceros create patchy fire regimes.
Sally Archibald, Author provided

Where to from here?

The input of scientists will be valuable in helping navigate big decisions about new and changing ecosystems.

Empirical data and models can monitor and forecast changes in biodiversity. For example, new modelling has allowed University of Melbourne researchers to identify alternative strategies for introducing planned or prescribed burning that reduces the risk of large bushfires to koalas.

New partnerships are also needed to meet the challenges ahead.

At the local and regional scale, Indigenous-led fire stewardship is an important approach for fostering relationships between Indigenous and non-Indigenous organisations and communities around the world.

Frank Lake, a co-author on our new paper, works with Yurok and Karuk fire practitioners, shown here burning under oaks.
Frank Lake, U.S Department of Agriculture Forest Service Pacific Southwest Research Station.

And international efforts to reduce greenhouse gas emissions and limit global warming are crucial to reduce the risk of extreme fire events. With more extreme fire events ahead of us, learning to understand and adapt to changes in fire regimes has never been more important.




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The Conversation


Luke Kelly, Senior Lecturer in Ecology and Centenary Research Fellow, University of Melbourne; Annabel Smith, Lecturer in Wildlife Management, The University of Queensland; Katherine Giljohann, Postdoctoral research fellow, University of Melbourne, and Michael Clarke, Professor of Zoology, La Trobe University

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

Humpback whales have been spotted in a Kakadu river. So in a fight with a crocodile, who would win?



Northern Territory Government

Vanessa Pirotta, Macquarie University

In recent months, three humpback whales were spotted in the East Alligator River in the Northern Territory’s Kakadu National Park. Contrary to its name, the river is full of not alligators but crocodiles. And its shallow waters are no place for a whale the size of a bus.

It was the first time humpback whales had been recorded in the river, and the story made international headlines. In recent days, one whale was spotted near the mouth of the river and scientists are watching it closely.

The whales’ strange detour threw up many questions. How did they end up in the river? What would they eat? Would they get stuck on the muddy river bank?

And of course, there was one big question I was repeatedly asked: in an encounter between a crocodile and a humpback whale, which animal would win?

A crocodile partially submerged in a river
The whales swam into a crocodile-infested river.
Dean Lewins/AAP

Scientists double-take

The humpback whales were first spotted in September this year by marine ecologist Jason Fowler and fellow scientists, during a fishing trip. Fowler told the ABC:

I noticed a big spout, a big blow on the horizon and I thought that’s a big dolphin … We were madly arguing with each other about what we were actually seeing. After four hours of raging debate we agreed we were looking at humpback whales in a river.

The whales had swum about 20 kilometres upstream. Fowler photographed the humpback whales’ dorsal fins as evidence, and reported the unusual sighting to authorities and scientists.

Thankfully, two whales returned to sea on their own, leaving just one in need of help. There was concern it might become stranded in the shallow, murky tidal waters. If this happened, it might be attacked by crocodiles – more on this in a minute.




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Experts considered a variety of tactics to encourage the whale back out to sea. These included physical barriers such as nets or boats, and playing the sounds of killer whales – known predators of humpback whales.

But none of these these options was needed. After 17 days, the last whale swam back to sea on its own.

The whale that spent two weeks in the river has recently returned and been spotted swimming around the mouth of the river. It appears to have lost weight – most likely the result of migration. It is now being monitored nearby in Van Diemen Gulf.

Questions are now being raised about the health of the animal, and why it has not headed south for Antarctic feedings waters.

A humpback whale that spent two weeks in the East Alligator River has recently been spotted nearby.
Dr Carol Palmer

So why were whales in the river?

The whales are part of Australia’s west coast humpback whale population, which each year travels from cold feeding waters off Antarctica to warm waters in the Kimberley to breed.

There are various theories as to why they swam into the East Alligator River. Humpback whales are extremely curious, and may have entered the river to explore the area.

Alternatively, they may have made a navigation error – also the possible reason behind September’s mass stranding of pilot whales in Tasmania.

And the big question – what about the crocs?

Long-term, a humpback whale’s chances of surviving in the East Alligator River are slim. The lower salinity level may cause them skin problems, and they may become stranded in the shallow waters – unable to move off the muddy bank. Here the animal might die from overheating, or its organs may be crushed by the weight of its body. Or, of course, the whale may be attacked by crocodiles.

In this case, my bet would be on the whale – if it was in relatively good condition and could swim well. Humpback whales are incredible powerful creatures. One flick of their large tail would often be enough to send a crocodile away.




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If a croc bit a whale, their teeth would likely penetrate the whale’s skin and thick blubber. But it would take a lot more to do serious harm. Whale skin has been shown to heal after traumatic events, including the case of a humpback whale cut by a boat propeller in Sydney 20 years ago. Dubbed Bladerunner, it survived but still bears deep scars.

Humpback whales are very large and powerful. One flick of their tail could send a crocodile away.
Dr Vanessa Pirotta

What next?

The whale sighting continues to fascinate experts. Scientists are hoping to take poo samples from the whale in Van Diemen Gulf, and could also collect whale snot to learn more about its health. However, the best case scenario would be to see the whale swim willingly to offshore waters.

This unusual tale will no doubt go down in Australian whale history. If nothing else, it reminds us of the vulnerability – and resilience – of these marine giants.


The author would like to thank Northern Territory Government whale expert Dr Carol Palmer for her assistance with this article.The Conversation

Vanessa Pirotta, Wildlife scientist, Macquarie University

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

Fierce female moles have male-like hormones and genitals. We now know how this happens.



Shutterstock

Jenny Graves, La Trobe University

Moles live a tough life underground. As a result, they’ve evolved helpful adaptations, such as excavator-like claws. Female moles in particular have evolved an unusual strategy: high levels of the male hormone testosterone.

This is an evolutionary advantage. It produces stronger muscles for digging and foraging and aggression, to help mothers defend themselves and their young.

Most of the year, female moles look and behave like males. They have masculinised genitals, with no external vagina and an enlarged clitoris. But when mating season comes, testosterone levels drop and a vagina is formed; mating and birth follow.

How they accomplish this remained a mystery for a long time. But now, the complete sequencing of the mole genome has revealed the genetic tweaks underpinning this strange cycle in female moles, by which reproductive organs (gonads) develop and hormones are produced.

Gonads and hormones

Male development in humans and other mammals is determined by chromosomes (the structures within cells of living things that contain genes). Females have two copies of an X chromosome. Males have a single X and a male-specific Y chromosome.

In XY embryos, a gene called SRY on the Y chromosome intervenes in a network of another 60 genes. SRY turns on testis genes and turns off ovary genes to transform a ridge of cells into a testis.

In the testis, one cell type becomes specialised to make sperm and another (Leydig cells) makes male hormones, including testosterone.




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Testosterone is responsible for the most visible sex differences in males, such as bigger bodies, more muscle mass, male genitalia and more aggression. In XX embryos, an alternate pathway makes an ovary, which pumps out oestrogen.

So in mammals, different genetic pathways drive the same patch of embryonic tissue to become either an ovary or a testis. Generally, there’s no in-between.

But female moles have a patch of testis within their ovaries.

An evolutionary balancing act

In 1993, it was discovered the basis for “intersex development” in female moles is a gonad with both ovarian and testicular tissue.

Like other male mammals, male moles have a Y chromosome, bearing the SRY gene which directs testis formation.

Also like other mammals, female moles lack a Y chromosome. Curiously, however, instead of developing ovaries they develop “ovotestes”, with ovarian tissue at one end and testicular tissue at the other.

The ovarian tissue makes eggs and gets larger during breeding, then regresses. The testicular tissue is full of Leydig cells that make testosterone (but not sperm). Outside of breeding season, it expands until it’s larger than the ovarian end.

This explains why female moles have male-like genitalia, and are muscular and aggressive. But how does a patch of testis form in female moles if they have no SRY gene to trigger the process?

Genetic tweaks behind ovotestis development

To look for genetic changes that could allow this to happen, a global consortium of scientists sequenced the entire mole genome.

They found no differences between moles and other mammals in the protein products of the 60-odd genes involved in sex determination. However, they did discover mutations that altered the regulation of two of these genes in female moles.

One difference was found in the DNA sequences of a gene that’s vital for developing testes: FGF9. In all mammals, this gene switches on testis growth in XY embryos and inhibits genes that determine ovarian development.

In females of other mammals, the FGF9 gene is turned off in the absence of SRY, but in female moles it stays on.

Genome sequencing revealed why: a big patch of DNA just upstream of FGF9 is flipped around in moles. This inversion removes the usual control sequences from the gene, allowing it to stay on for longer in XX embryos.

The other gene impacted in female moles is CYP17A1, which codes for an enzyme that’s key to producing androgens (male hormones). In female moles, this gene and its surrounds have two extra copies, which increases testosterone output.

To show these genomic changes were indeed responsible for masculinising female moles, the researchers introduced them into mice, causing sex reversal and higher testosterone levels.

It’s important to note these evolutionary changes are in the regulation of gene activity, rather than in the regulation of protein products — which could compromise other normal functions.

Clownfish (_Amphiprioninae_).
Other than mammals, many marine animals have gender-bending tendencies. Clownfish always begin life as hermaphrodites carrying both female and male reproductive organs. Later in life, males can become female on an as-needed basis to mate with other males.
Istvan/Flickr, CC BY



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What we learn from a fish that can change sex in just 10 days


What this means for sex and evolution

Since mammals, including humans, develop as either males or females, we’ve been accustomed to regard testis or ovary development in the embryo as strict alternatives, depending on an on/off switch (the presence or absence of the Y chromosome and SRY gene).

But we now know there’s a complex gene network full of checks and balances that is the basis for alternate pathways of sexual development.

There are many studies of human babies born with mutations in one of these genes. This points to a more complex picture of the wiring behind the “switch” responsible for variation in human sexual development.

There are fierce females in other mammal species, too. Female spotted hyenas are bigger and more dominant than males and have male-like genitalia. We don’t know how this change works at a genetic level.

A female spotted hyena in the wold.
The spotted hyena, Crocuta crocuta (also known as the ‘laughing hyena’) is native to sub-Saharan Africa. In females such as this one, the clitoris is shaped and positioned like a penis that can become erect.
Shutterstock

The downside of this is that mating is tricky. Cubs are birthed through the female’s narrow phallus. Mothers and/or cubs often die during this fraught process.

So while these larger, more aggressive females rule the hyena roost and get first pick at meals, like most things in nature, it seems this comes at a price.

Big fierce female moles and hyenas remind us the natural world, as always, features unique evolutionary differences — enlightening our view on human variation.The Conversation

Jenny Graves, Distinguished Professor of Genetics and Vice Chancellor’s Fellow, La Trobe University

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

3 billion animals were in the bushfires’ path. Here’s what the royal commission said (and should’ve said) about them


Ashleigh Best, University of Melbourne; Christine Parker, University of Melbourne, and Lee Godden, University of Melbourne

The Black Summer bushfires were devastating for wildlife, with an estimated three billion wild animals killed, injured or displaced. This staggering figure does not include the tens of thousands of farm animals who also perished.

The bushfire royal commission’s final report, released on October 30, recognised the gravity of the fires’ extraordinary toll on animals.




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Click through the tragic stories of 119 species still struggling after Black Summer in this interactive (and how to help)


It recommended governments improve wildlife rescue arrangements, develop better systems for understanding biodiversity and clarify evacuation options for domestic animals.

While these changes are welcome and necessary, they’re not sufficient. Minimising such catastrophic impacts on wildlife and livestock also means reducing their exposure to these hazards in the first place. And unless we develop more proactive strategies to protect threatened species from disasters, they’ll only become more imperilled.

What the royal commission recommended

The royal commission recognised the need for wildlife rescuers to have swift and safe access to fire grounds.

In the immediate aftermath of the bushfires, some emergency services personnel were confused about the roles and responsibilities of wildlife rescuers. This caused delays in rescue operations.

To address this issue, the royal commission sensibly suggested all state and territory governments integrate wildlife rescue functions into their general disaster planning frameworks. This would improve coordination between different response agencies.




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The bushfire royal commission has made a clarion call for change. Now we need politics to follow


Another issue raised by the commission was that Australia does not have a comprehensive, central source of information about its native flora and fauna. This is, in part, because species listing processes are fragmented across different jurisdictions.

For example, a marsupial, the white-footed dunnart, is listed as vulnerable in NSW, but is not on the federal government’s list of threatened species.

To better manage and protect wild animals, governments need more complete information on, for example, their range and population, and how climate change threatens them.

As a result, the royal commission recommended governments collect and share more accurate information so disaster response and recovery efforts for wildlife could be more targeted, timely and effective.

A wildlife rescuer holds a koala with burnt feet in a burnt forest
Adelaide wildlife rescuer Simon Adamczyk takes a koala to safety on Kangaroo Island.
AAP Image/David Mariuz

Helping animals help themselves

While promising, the measures listed in the royal commission’s final report will only tweak a management system for wildlife already under stress. Current legal frameworks for protecting threatened species are reactive. By the time governments intervene, species have often already reached a turning point.

Governments must act to allow wild animals the best possible chances of escaping and recovering on their own.

This means prioritising the protection and restoration of habitat that allows animals to get to safety. As a World Wildlife Fund report explains, an animal’s ability to flee the fires and find safe, unburnt habitat — such as mesic (moist) refuges in gullies or near waterways — directly influenced their chances of survival.




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Summer bushfires: how are the plant and animal survivors 6 months on? We mapped their recovery


Wildlife corridors also assist wild animals to survive and recover from disasters. These connect areas of habitat, providing fast moving species with safe routes along which they can flee from hazards.

And these corridors help slow moving species, such as koalas, to move across affected landscapes after fires. This prevents them from becoming isolated, and enables access to food and water.

Hazard reduction activities, such as removing dry vegetation that fuels fires, were also a focus for the royal commission. These can coexist with habitat conservation when undertaken in ecologically-sensitive ways.

As the commission recognised, Indigenous land and fire management practices are informed by intimate knowledge of plants, animals and landscapes. These practices should be integrated into habitat protection policies in consultation with First Nations land managers.

The commission also suggested natural hazards, such as fire, be counted as a “key threatening process” under national environment law. But it should be further amended to protect vulnerable species under threat from future stressors, such as disasters.




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Let there be no doubt: blame for our failing environment laws lies squarely at the feet of government


Governments also need to provide more funding to monitor compliance with this law. Another new World Wildlife Fund report warns that unless it is properly enforced, a further 37 million native animals could be displaced or killed as a result of habitat destruction this decade.

And, as we saw last summer, single bushfire events can push some populations much closer to extinction. For example, the fires destroyed a large portion of the already endangered glossy black-cockatoo’s remaining habitat.

What about pets and farm animals?

Pets and farm animals featured in the commission’s recommendations too.

During the bushfires, certain evacuation centres didn’t cater for these animals. This meant some evacuees chose not to use these facilities because they couldn’t take their animals with them.

To guide the community in future disasters, the commission said plans should clearly identify whether or not evacuation centres can accommodate people with animals.




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Seven ways to protect your pets in an emergency


Evacuation planning is crucial to effective disaster response. However, it is unfortunately not always feasible to move large groups of livestock off properties at short notice.

For this reason, governments should help landholders to mitigate the risks hazards pose to their herds and flocks. Researchers are already starting to do this by investigating the parts of properties that were burnt during the bushfires. This will help farmers identify the safest paddocks for their animals in future fire seasons.

Disasters are only expected to become more intense and extreme as the climate changes. And if we’re to give our pets, livestock and unique wildlife the best chance at surviving, it’s not enough only to have sound disaster response. Governments must preemptively address the underlying sources of animals’ vulnerability to hazards.




Read more:
How we plan for animals in emergencies


The Conversation


Ashleigh Best, PhD Candidate and Teaching Fellow, University of Melbourne; Christine Parker, Professor of Law, University of Melbourne, and Lee Godden, Director, Centre for Resources, Energy and Environmental Law, Melbourne Law School, University of Melbourne

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

Photos from the field: these magnificent whales are adapting to warming water, but how much can they take?



Olaf Meynecke, Author provided

Olaf Meynecke, Griffith University

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.


The start of November marks the end of the whale season in the Southern Hemisphere. As summer approaches, whales that were breeding along the east and west coasts of Australia, Africa and South America will now swim further south to feed around Antarctica.

This annual cycle of whales coming and going has taken place for at least 10,000 years. But rising ocean temperatures from climate change are challenging this process, and my colleagues and I have already seen signs that humpback whales are changing their feeding, migration and breeding patterns to adapt.




Read more:
Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales


As krill stocks decline and ocean circulation is set to change more drastically, climate change remains an unprecedented threat to whales. The challenge now is to forecast what will happen next to better protect them.

Losing krill is the biggest threat

I’m part of an international team of researchers trying to learn what the next 100 years might look like for humpback whales in the Southern Hemisphere, and how they’ll adapt to changing ocean conditions.

Whales depend on recurring environmental conditions and oceanographic features, such as temperature, circulation, changing seasons and biogeochemical (nutrient) cycles. In particular, these features influence the availability of krill in the Southern Ocean, their biggest food source.

Whales are particularly sensitive to this because they need enormous amounts of food to develop sufficient fat reserves to migrate, give birth and nurse a calf, as they don’t eat during this time.

In fact, models predict declines in krill from climate change could lead to local extinctions of whales by 2100. This includes Pacific populations of blue, fin and southern right whales, as well as fin and humpback whales in the Atlantic and Indian oceans.




Read more:
Climate change threatens Antarctic krill and the sea life that depends on it


Still, when it comes to their migration and breeding cycles, recent studies have shown humpback whales can adapt with changes in ocean temperature and circulation at a remarkable level.

Whales can adapt to warming water, but at what cost?

In a long term study from the Northern Hemisphere, scientists found the arrival of humpback whales in some feeding grounds shifted by one day per year over a 27-year period in response to small fluctuations in ocean temperatures.

This led to a one-month shift in arrival time, but a big concern is whether they can continue to time their arrival with their prey in the future when the water gets warmer still.

Likewise, in breeding grounds near Hawaii, the number of mother and calf humpback whale sightings dropped by more than 75% between 2013 and 2018. This coincided with persistent warming in the Alaskan feeding grounds these whales had migrated from.

Collecting humpback whale exhale (“whale snot”)

But humpback whales shifting their distribution and behaviour can cause unexpected human encounters, and cause new challenges that weren’t an issue previously.

Research from earlier this year found humpback whales switched to fish as their main prey when the sea surface temperature in the California current system increased in a heatwave. This has been leading to record numbers of entanglements with gear from coastal fisheries.




Read more:
I measure whales with drones to find out if they’re fat enough to breed


And between 2013 and 2016, we documented hundreds of newborn humpback whales in subtropical and temperate shallow bays on the east coast of Australia, 1,000 kilometres further south from their traditional breeding areas off the Great Barrier Reef.

However, since these aren’t designated calving areas, the newborns aren’t well protected from getting tangled in shark nets or colliding with jet skis or cruise ships.

Protecting whales

The Whales and Climate Program is the largest project of its kind, combining hundreds of thousands of humpback whale sightings and advanced modelling techniques. Our aim is to advance whale conservation in response to climate change, and learn how it threatens their recovery after decades of over-exploitation by the whaling industry.

Each whale season between June and October, I sail out to the open ocean. This means I have unique opportunities to see and engage with whales, especially during the breeding season. The following photos show some of our breathtaking encounters, and can remind us of our marine ecosystem’s fragile beauty.

A humpback whale fin

Olaf Meynecke, Author provided
Breaching humpback whale in front of buildings

Olaf Meynecke, Author provided

During one of our boat-based surveys on the Gold Coast, we encountered this acrobatic humpback whale calf, shown in the photos above. We counted 254 breaches in two hours, making it the record holder of most breaches in our 10 years of observation.

To check on whales’ health, we collect and study the air they exhale through their blow hole (“whale snot”), and measure their size at different times of the year. The photo above shows me tagging a whale with CATs suction cup tags, to collect data on short term changes in their movement patterns.

Close up of a humpback whale's mouth

Olaf Meynecke, Author provided

In regions where the whales adapt to ocean changes and, as such, move closer to shore for feeding and shift their breeding grounds, there’s a higher risk of entanglements and other human encounters. This is particularly concerning when they travel outside protected areas.

A newborn humpback whale resting on its mum's head

Olaf Meynecke, Author provided

Look closely and you can see a newborn humpback, just one to three days old, resting on its mother’s head.

In the first days of life, baby humpback whales sink easily and aren’t able to stay on the water surface for long. They need their mothers’ support to stay on the surface to breathe.

Once they’ve gained enough fat from the mothers milk they become positively buoyant (meaning they can float), making it easier for them to breathe.

Photo of a whale underwater

Olaf Meynecke, Author provided

A final note — during one of our land-based whale surveys this year, a keen whale watcher approached us, and we helped him find the whales with our binoculars. I will never forget the joy in his face when he spotted them.

It’s a joy I hope many future generations can experience. To ensure this, we need to understand how we can best protect whales in a changing climate.




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The Conversation


Olaf Meynecke, Research Fellow in Marine Science, Griffith University

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

UN report says up to 850,000 animal viruses could be caught by humans, unless we protect nature



Shutterstock

Katie Woolaston, Queensland University of Technology and Judith Lorraine Fisher

Human damage to biodiversity is leading us into a pandemic era. The virus that causes COVID-19, for example, is linked to similar viruses in bats, which may have been passed to humans via pangolins or another species.

Environmental destruction such as land clearing, deforestation, climate change, intense agriculture and the wildlife trade is putting humans into closer contact with wildlife. Animals carry microbes that can be transferred to people during these encounters.

A major report released today says up to 850,000 undiscovered viruses which could be transferred to humans are thought to exist in mammal and avian hosts.

The report, by The United Nations’ Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), says to avoid future pandemics, humans must urgently transform our relationship with the environment.

Covid-19 graphic
Microbes can pass from animals to humans, causing disease pandemics.
Shutterstock

Humans costs are mounting

The report is the result of a week-long virtual workshop in July this year, attended by leading experts. It says a review of scientific evidence shows:

…pandemics are becoming more frequent, driven by a continued rise in the underlying emerging disease events that spark them. Without preventative strategies, pandemics will emerge more often, spread more rapidly, kill more people, and affect the global economy with more devastating impact than ever before.

The report says, on average, five new diseases are transferred from animals to humans every year – all with pandemic potential. In the past century, these have included:

  • the Ebola virus (from fruit bats),
  • AIDS (from chimpazees)
  • Lyme disease (from ticks)
  • the Hendra virus (which first erupted at a Brisbane racing stable in 1994).

The report says an estimated 1.7 million currently undiscovered viruses are thought to exist in mammal and avian hosts. Of these, 540,000-850,000 could infect humans.

But rather than prioritising the prevention of pandemic outbreaks, governments around the world primarily focus on responding – through early detection, containment and hope for rapid development of vaccines and medicines.

Doctor giving injection to patient
Governments are focused on pandemic responses such as developing vaccines, rather than prevention.
Shutterstock

As the report states, COVID-19 demonstrates:

…this is a slow and uncertain path, and as the global population waits for vaccines to become available, the human costs are mounting, in lives lost, sickness endured, economic collapse, and lost livelihoods.

This approach can also damage biodiversity – for example, leading to large culls of identified carrier-species. Tens of thousands of wild animals were culled in China after the SARS outbreak and bats continue to be persecuted after the onset of COVID-19.

The report says women and Indigenous communities are particularly disadvantaged by pandemics. Women represent more then 70% of social and health-care workers globally, and past pandemics have disproportionately harmed indigenous people, often due to geographical isolation.




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It says pandemics and other emerging zoonoses (diseases that have jumped from animals to humans) likely cause more than US$1 trillion in economic damages annually. As of July 2020, the cost of COVID-19 was estimated at US $8-16 trillion globally. The costs of preventing the next pandemic are likely to be 100 times less than that.

People wearing masks in a crowd
The cost to governments of dealing with pandemics far outweighs the cost of prevention.
Shutterstock

A way forward

The IPBES report identifies potential ways forward. These include:

• increased intergovernmental cooperation, such as a council on pandemic prevention, that could lead to a binding international agreement on targets for pandemic prevention measures

• global implementation of OneHealth policies – policies on human health, animal health and the environment which are integrated, rather than “siloed” and considered in isolation

• a reduction in land-use change, by expanding protected areas, restoring habitat and implementing financial disincentives such as taxes on meat consumption

• policies to reduce wildlife trade and the risks associated with it, such as increasing sanitation and safety in wild animal markets, increased biosecurity measures and enhanced enforcement around illegal trade.

Societal and individual behaviour change will also be needed. Exponential growth in consumption, often driven by developed countries, has led to the repeated emergence of diseases from less-developed countries where the commodities are produced.

So how do we bring about social change that can reduce consumption? Measures proposed in the report include:

  • education policies

  • labelling high pandemic-risk consumption patterns, such as captive wildlife for sale as pets as either “wild-caught” or “captive-bred” with information on the country where it was bred or captured

  • providing incentives for sustainable behaviour

  • increasing food security to reduce the need for wildlife consumption.

People inspecting haul of wildlife products
Cracking down on the illegal wildlife trade will help prevent pandemics.
AP

An Australian response

Australia was one of the founding member countries of IPBES in 2012 and so has made an informal, non-binding commitment to follow its science and policy evidence.

However, there are no guarantees it will accept the recommendations of the IPBES report, given the Australian government’s underwhelming recent record on environmental policy.

For example, in recent months the government has so far refused to sign the Leaders’ Pledge for Nature. The pledge, instigated by the UN, includes a commitment to taking a OneHealth approach – which considers health and environmental sustainability together – when devising policies and making decisions.

The government cut funding of environmental studies courses by 30%. It has sought to reduce so called “green tape” in national environmental legislation, and its economic response to the pandemic will be led by industry and mining – a focus that creates further pandemic potential.




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Finally, Australia is one of few countries without a national centre for disease control and pandemics.

But there are good reasons for hope. It’s within Australia’s means to build an organisation focused on a OneHealth approach. Australia is one of the most biologically diverse countries on the planet and Australians are willing to protect it. Further, many investors believe proper environmental policy will aid Australia’s economic recovery.

Finally, we have countless passionate experts and traditional owners willing to do the hard work around policy design and implementation.

As this new report demonstrates, we know the origins of pandemics, and this gives us the power to prevent them.The Conversation

Katie Woolaston, Lawyer, Queensland University of Technology and Judith Lorraine Fisher, Adjunct Professor University of Western Australia, Institute of Agriculture

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

Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales



University of Auckland tohorā research team, Department of Conservation permit DJI

Emma Carroll

After close to a decade of globe-spanning effort, the genome of the southern right whale has been released this week, giving us deeper insights into the histories and recovery of whale populations across the southern hemisphere.

Up to 150,000 southern right whales were killed between 1790 and 1980. This whaling drove the global population from perhaps 100,000 to as few as 500 whales in 1920. A century on, we estimate there are 12,000 southern right whales globally. It’s a remarkable conservation success story, but one facing new challenges.

A southern right whale calf breaches in the subantarctic Auckland Islands.
A southern right whale calf breaches in the subantarctic Auckland Islands.
University of Auckland tohorā research team, Author provided

The genome represents a record of the different impacts a species has faced. With statistical models we can use genomic information to reconstruct historical population trajectories and patterns of how species interacted and diverged.

We can then link that information with historical habitat and climate patterns. This look back into the past provides insights into how species might respond to future changes. Work on penguins and polar bears has already shown this.

But we also have a new and surprising short-term perspective on the population of whales breeding in the subantarctic Auckland Islands group — Maungahuka, 450km south of New Zealand.

Spying on whales via satellite

Known as tohorā in New Zealand, southern right whales once wintered in the bays and inlets of the North and South Islands of Aotearoa, where they gave birth and socialised. Today, the main nursery ground for this population is Port Ross, in the subantarctic Auckland Islands.

Adult whales socialise at both the Auckland and Campbell Islands during the austral winter. Together these subantarctic islands are internationally recognised as an important marine mammal area.

In August 2020, I led a University of Auckland and Cawthron Institute expedition to the Auckland Islands. We collected small skin samples for genetic and chemical analysis and placed satellite tags on six tohorā. These tags allowed us to follow their migrations to offshore feeding grounds.

It matters where tohorā feed and how their populations recover from whaling because the species is recognised as a sentinel for climate change throughout the Southern Hemisphere. They are what we describe as “capital” breeders — they fast during the breeding season in wintering grounds like the Auckland Islands, living off fat reserves gained in offshore feeding grounds.

Females need a lot in the “bank” because their calves need a lot of energy. At 4-5m at birth, these calves can grow up to a metre a month. This investment costs the mother 25% of her size over the first few months of her calf’s life. It’s no surprise that calf growth depends on the mother being in good condition.




Read more:
I measure whales with drones to find out if they’re fat enough to breed


Females can only breed again once they’ve regained their fat capital. Studies in the South Atlantic show wintering grounds in Brazil and Argentina produce more calves when prey is more abundant, or environmental conditions suggest it should be.

The first step in understanding the relationship between recovery and prey in New Zealand is to identify where and on what tohorā feed. The potential feeding areas for our New Zealand population could cover roughly a third of the Southern Ocean. That’s why we turn to technologies like satellite tags to help us understand where the whales are going and how they get there.

Where tohorā go

So far, all tracked whales have migrated west; away from the historical whaling grounds to the east near the Chatham Islands. As they left the Auckland Islands, two whales visited other oceanic islands — skirting around Macquarie Island and visiting Campbell Island.

It also seems one whale (Bill or Wiremu, identified as male using genetic analysis of his skin sample) may have reached his feeding grounds, likely at the subtropical convergence. The clue is in the pattern of his tracks: rather than the continuous straight line of a whale migrating, it shows the doughnuts of a whale that has found a prey patch.

Migratory track of southern right whale Bill/Wiremu, where the convoluted track could indicate foraging behaviour.

The subtropical convergence is an area of the ocean where temperature and salinity can change rapidly, and this can aggregate whale prey. Two whales we tracked offshore from the Auckland Islands in 2009 visited the subtropical convergence, but hundreds of kilometres to the east of Bill’s current location.

As Bill and his compatriots migrate, we’ve begun analysing data that will tell us about the recovery of tohorā in the past decade. The most recent population size estimate we have is from 2009, when there were about 2,000 whales.




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I am using genomic markers to learn about the kin relationships and, in doing so, the population’s size and growth rate. Think of it like this. Everybody has two parents and if you have a small population, say a small town, you are more likely to find those parents than if you have a big population, say a city.

This nifty statistical trick is known as the “close kin” approach to estimating population size. It relies on detailed understanding of the kin relationships of the whales — something we have only really been able to do recently using new genomic sequencing technology.

Global effort to understand climate change impacts

Globally, southern right whales in South Africa and Argentina have bred less often over the past decade, leading to a lower population growth rate in Argentina.

Concern over this slowdown in recovery has prompted researchers from around the world to work together to understand the relationship between climate change, foraging ecology and recovery of southern right whales as part of the International Whaling Commission Southern Ocean Research Partnership.

The genome helps by giving us that long view of how the whales responded to climate fluctuations in the past, while satellite tracking gives us the short view of how they are responding on a day-to-day basis. Both will help us understand the future of these amazing creatures.The Conversation

Emma Carroll, Rutherford Discovery Fellow

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