Scientists capture rare footage of mother skink fighting a deadly brown snake to protect her babies



Author provided

Gregory Watson, University of the Sunshine Coast and Jolanta Watson, University of the Sunshine Coast

Unlike many mammals and birds, most reptiles show little sign of being caring parents. But our new research shows one lizard species may be more doting parents than we thought – the adults risking their own safety to protect their babies.

We used cameras in the Snowy Mountains of New South Wales to study the Cunningham’s skink. We were surprised to record evidence of the lizards actively defending their newborn offspring against formidable predators. Our findings are outlined in a paper released today.

Most startlingly, we recorded a mother skink aggressively attacking a large, deadly brown snake while her babies watched on. We also witnessed 12 incidents of skinks chasing magpies away from their young.

We originally set out to record how species such as skinks will cope with climate change. But this evolved into a study of the fascinating and surprising social bonds between lizard offspring and their parents.

Adult and young skinks sun-baking together
Sun-loving skinks live together in social groups.
Authors provided

What is the Cunningham’s skink?

The Cunningham’s skink (Egernia cunninghami) is a large, sun-loving, spiny lizard native to southeast Australia. It’s named after Alan Cunningham, an explorer who collected the first specimen in the Blue Mountains.

The skinks are active during the day. They feed on invertebrates such as insects, snails and slugs, as well as vegetation.

The Cunningham’s skink lives in social groups – a behaviour very rare among lizards and reptiles. In these groups, mothers give birth to live young (rather than eggs) then live alongside their kids, sometimes for several years.

The species has strength in numbers – living in a group makes it easier to spot threats, which helps the group survive.

Adult and young skinks sun-baking together
Thew offspring of Cunningham’s skinks can stay with the parents for several years.

The mother of all discoveries

Using video and thermal imaging, we observed the skinks on 32 days over three years.

Among reptiles, evidence of parental protection in their natural environment has been rare and typically anecdotal. We witnessed four birthing sessions, and then monitored skink encounters in the presence of their offspring.




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Videoing nature can be tricky. Often, the action takes place away from where you’ve directed your camera. So when we saw a snake, it was a scramble to get a free video camera and start recording.

We witnessed two separate encounters with an eastern brown snake. The first involved the snake sneaking up on six-day-old skinks basking in the sun (see footage below). We recorded the mother running towards the predator and biting it for several seconds. The snake writhes around before the mother releases her grip and returns unharmed to her young.

The following year, we encountered two adult skinks attacking another eastern brown snake in bushes. Juvenile skinks were nearby. The skinks bit tight to the snake’s body, and the snake dragged them for more than 15 metres before the skinks released their grip.

Snakes were not the only predator vanquished by the protective skink parents – Cunningham’s skinks regularly chased magpies away from their young. We observed 12 encounters between skinks and magpies. In each case, an adult skink aggressively chased and/or attacked the magpie after the bird came close to the group.

Thermal camera image showing the mother skink attacking the snake while her babies watch on
Thermal camera image showing the mother skink attacking the snake while her babies watch on.

What does this all mean?

Some animals rarely interact with others of the same species, even their offspring. In fact, available data suggests infanticide – where mature animals kill young offspring of the same species – can occur among some skink species.

We saw no such behaviour among the Cunningham’s skink, or aggression towards each other.

While the aggression of the adult skinks towards predators took place in the presence of young, the adults may have been exhibiting self-defence or territorial behaviour. Regardless, the attacks on predators in the presence of newborns does reflect parental care, either directly or indirectly. Our future field excursions will hopefully shed more light on this.

Understanding the factors that bring parents and offspring together, and keep them together, is important in our broader understanding of social evolution – that is, how social interactions of species arise, change and are maintained.

It will also help us understand how animals cooperating with and caring for each other can benefit both the individual, and the whole.




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The Conversation


Gregory Watson, Senior Lecturer, Science, University of the Sunshine Coast and Jolanta Watson, Lecturer in Science, University of the Sunshine Coast

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

Are young trees or old forests more important for slowing climate change?



Jeremy Kieran/Unsplash, CC BY-SA

Tom Pugh, University of Birmingham

Forests are thought to be crucial in the fight against climate change – and with good reason. We’ve known for a long time that the extra CO₂ humans are putting in the atmosphere makes trees grow faster, taking a large portion of that CO₂ back out of the atmosphere and storing it in wood and soils.

But a recent finding that the world’s forests are on average getting “shorter and younger” could imply that the opposite is happening. Adding further confusion, another study recently found that young forests take up more CO₂ globally than older forests, perhaps suggesting that new trees planted today could offset our carbon sins more effectively than ancient woodland.

How does a world in which forests are getting younger and shorter fit with one where they are also growing faster and taking up more CO₂? Are old or young forests more important for slowing climate change? We can answer these questions by thinking about the lifecycle of forest patches, the proportion of them of different ages and how they all respond to a changing environment.




Read more:
Using forests to manage carbon: a heated debate


The forest carbon budget

Let’s start by imagining the world before humans began clearing forests and burning fossil fuels.

In this world, trees that begin growing on open patches of ground grow relatively rapidly for their first several decades. The less successful trees are crowded out and die, but there’s much more growth than death overall, so there is a net removal of CO₂ from the atmosphere, locked away in new wood.

As trees get large two things generally happen. One, they become more vulnerable to other causes of death, such as storms, drought or lightning. Two, they may start to run out of nutrients or get too tall to transport water efficiently. As a result, their net uptake of CO₂ slows down and can approach zero.

Eventually, our patch of trees is disturbed by some big event, like a landslide or fire, killing the trees and opening space for the whole process to start again. The carbon in the dead trees is gradually returned to the atmosphere as they decompose.

The vast majority of the carbon is held in the patches of big, old trees. But in this pre-industrial world, the ability of these patches to continue taking up more carbon is weak. Most of the ongoing uptake is concentrated in the younger patches and is balanced by CO₂ losses from disturbed patches. The forest is carbon neutral.

A misty forest scene.
New trees absorb lots of carbon, old trees store more overall and dead trees shed their carbon to the atmosphere.
Greg Rosenke/Unsplash, CC BY-SA

Now enter humans. The world today has a greater area of young patches of forest than we would naturally expect because historically, we have harvested forests for wood, or converted them to farmland, before allowing them to revert back to forest. Those clearances and harvests of old forests released a lot of CO₂, but when they are allowed to regrow, the resulting young and relatively short forest will continue to remove CO₂ from the atmosphere until it regains its neutral state. In effect, we forced the forest to lend some CO₂ to the atmosphere and the atmosphere will eventually repay that debt, but not a molecule more.

But adding extra CO₂ into the atmosphere, as humans have done so recklessly since the dawn of the industrial revolution, changes the total amount of capital in the system.

And the forest has been taking its share of that capital. We know from controlled experiments that higher atmospheric CO₂ levels enable trees to grow faster. The extent to which the full effect is realised in real forests varies. But computer models and observations agree that faster tree growth due to elevated CO₂ in the atmosphere is currently causing a large carbon uptake. So, more CO₂ in the atmosphere is causing both young and old patches of forest to take up CO₂, and this uptake is larger than that caused by previously felled forests regrowing.

The effect of climate change

But the implications of climate change are quite different. All else being equal, warming tends to increase the likelihood of death among trees, from drought, wildfire or insect outbreaks. This will lower the average age of trees as we move into the future. But, in this case, that younger age does not have a loan-like effect on CO₂. Those young patches of trees may take up CO₂ more strongly than the older patches they replace, but this is more than countered by the increased rate of death. The capacity of the forest to store carbon has been reduced. Rather than the forest loaning CO₂ to the atmosphere, it’s been forced to make a donation.

So increased tree growth from CO₂ and increased death from warming are in competition. In the tropics at least, increased growth is still outstripping increased mortality, meaning that these forests continue to take up huge amounts of carbon. But the gap is narrowing. If that uptake continues to slow, it would mean more of our CO₂ emissions stay in the atmosphere, accelerating climate change.

Overall, both young and old forests play important roles in slowing climate change. Both are taking up CO₂, primarily because there is more CO₂ about. Young forests take up a bit more, but this is largely an accident of history. The extra carbon uptake we get from having a relatively youthful forest will diminish as that forest ages. We can plant new forests to try to generate further uptake, but space is limited.

But it’s important to separate the question of uptake from that of storage. The world’s big, old forests store an enormous amount of carbon, keeping it out of the atmosphere, and will continue to do so, even if their net CO₂ uptake decreases. So long as they are not cut down or burned to ashes, that is.The Conversation

Tom Pugh, Reader in Biosphere-Atmosphere Exchange, University of Birmingham

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

Ocean acidification causes young corals to develop deformed skeletons


Taryn Foster, University of Western Australia and Peta Clode, University of Western Australia

Coral reefs around the world are facing a whole spectrum of human-induced disturbances that are affecting their ability to grow, reproduce and survive. These range from local pressures such as overfishing and sedimentation, to global ones such as ocean acidification and warming. With the third global coral bleaching event underway, we now more than ever, need to understand how coral responds to these stressors.

Our new research, published in Science Advances, now shows that young corals develop deformed and porous skeletons when they grow in more acidified waters, potentially making it more difficult for them to establish themselves on the reef and survive to adulthood.

Juvenile corals

Corals vary in their responses to stress, not only between species and location, but also among different stages of their life cycle. Juvenile corals are extremely important to the health of a reef, as they help to replenish the reef’s coral population and also help it recover from severe disturbances such as bleaching and storms.

However, newly settled young corals are small (typically about 1 mm across) and therefore very vulnerable to things like overgrowth and predation. To survive into adulthood they need to grow quickly out of this vulnerable size class. To do that they need to build a robust skeleton that can maintain its structural integrity during growth.

Two major factors that affect coral skeletal growth are ocean temperature and carbon dioxide concentration. Both are on the rise as we continue to emit huge amounts of CO₂ into the atmosphere. Generally with adult corals, increased temperature and CO₂ both reduce growth rates. But this varies considerably depending on the species and the environmental conditions to which the coral has been exposed.

Much less is known about the impacts of these factors on juvenile corals. This is mainly because their small size makes them more difficult to study, and they are only usually around once a year during the annual coral spawn. The corals we studied spawn for just a couple of hours, on one night of the year, meaning that our study hinged on taking samples during a crucial one-hour window.

When collecting the samples, at Western Australia’s Basile Island in the Houtman Abrolhos archipelago in March 2013, we watched the adult spawners each night waiting to see if they would spawn and, when they did, we worked all night fertilising the eggs to collect our juvenile samples.

Having collected our elusive coral samples, we cultured and grew newly settled coral recruits under temperature and CO₂ conditions that are expected to occur by the end of the century if no action is taken to curb the current trajectory of CO₂ emissions.

We then used three-dimensional X-ray microscopy to look at how these conditions affect the structure of the skeleton. This technique involves taking many X-ray projection images of the sample (in this case around 3,200) and then reconstructing them into a 3D image.

A 3D X-ray microscopy image of a one-month-old coral skeleton.
Taryn Foster/Science Advances, Author provided

Deformed and porous skeletons

Corals grown under high-CO₂ conditions not only showed reduced skeletal growth overall, but developed a range of skeletal deformities.

These included reduced overall size, gaps, over- and under-sized structures, and in some cases, large sections of skeleton completely missing. We also saw deep pitting and fractures in the skeletons of corals grown under high CO₂, typical of skeletal dissolution and structural fragility.

Surprisingly, increased temperature did not have a negative impact on skeletal growth and for some measures even appeared to help to offset the negative impacts of high CO₂ – a response we think may be unique to sub-tropical juveniles.

Nevertheless, our study highlights the vulnerability of juvenile corals to ocean acidification.

Under the current CO₂ emissions trajectory, our findings indicate that young corals will not be able to effectively build their skeletons. This could have wider implications for coral reef health, because without healthy new recruits, reefs will not replenish and will be less able to bounce back from disturbances.

The effect of temperature in this study however, was both a surprising and welcome finding. There is a lot of variation even between species, but it is possible that subtropical organisms have more plasticity due to their natural exposure to a wider range of conditions. This could indicate that subtropical juveniles may have an unexpected edge when it comes to ocean warming.

The Conversation

Taryn Foster, PhD Candidate, School of Earth and Environment, University of Western Australia and Peta Clode, Associate Professor, University of Western Australia

This article was originally published on The Conversation. Read the original article.

Hunter Region Botanic Gardens


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Southern Wetlands

ABOVE: The Southern Wetlands Boardwalk – Hunter Region Botanic Gardens

Late last week I decided I should do something with the final day of my annual leave that I had taken this time round, so I thought I’d pop into the Hunter Region Botanic Gardens near Raymond Terrace in New South Wales, Australia. I had been here before, but that was a long time ago. I wasn’t impressed on that first visit, so after more then a decade had it improved? Well that was the question I was keen to answer.

Rotunda

ABOVE: The Rotunda  BELOW: Succulents Section

Succulents

There was a $4.00 ‘escape’ fee, which would allow a token to be purchased and then the boom gate would rise once it was placed into the proper slot at the exit. So no entrance fee, just an exit fee. I was willing to pay this for a quick look and…

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Blackbutt Reserve


Kevin's Daily Photo, Video, Quote or Link

Since I was unable to visit Gap Creek Falls the other day, I decided I might pop in to have a look at the new animal enclosures at Blackbutt Reserve near Newcastle. I will say straight off the bat that I do have something of a prejudice against Blackbutt Reserve, as I see the place as nothing like a natural bush setting, it being far too ‘corrupted’ by human activity, weeds and the like. Having said that it is a good place for a family or group outing/event. It certainly has its place, but it is not a true nature reserve (in my opinion).

Visitor Centre

ABOVE: Visitor Centre

I do think that some well designed animal and bird enclosures at Blackbutt could lift the value of the reserve dramatically and make it a really great place for families, especially young families. There are opportunities for educational visits for kids, possible environmental…

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