Seminar series highlights: Nathalie Pettorelli and John Hutchinson

space monitoring

As mentioned previously on the blog, Andrew Jackson and I started a new module this year called “Research Comprehension”. The module revolves around our Evolutionary Biology and Ecology seminar series and the continuous assessment for the module is in the form of blog posts discussing these seminars. We posted a selection of these earlier in the term, but now that the students have had their final degree marks we wanted to post the blogs with the best marks. This means there are more blog posts for some seminars than for others, though we’ve avoided reposting anything we’ve posted previously. We hope you enjoy reading them, and of course congratulations to all the students of the class of 2014! – Natalie

Here’s Sam Preston’s take on Dr. Nathalie Pettorelli’s seminar, “Monitoring biodiversity from space: a wealth of opportunities” and Gina McLoughlin’s views on Professor John Hutchinson‘s seminar, “Six-toed elephants and knobbly-kneed birds! Case studies in the evolution of limb sesamoid bones.”

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Three New Reasons I Want a Satellite

Sam Preston

Despite the best efforts of Google spying on my house and Lee Tamahori making Die Another Day, I still think satellites are awesome. Who among us can honestly say that man-made objects floating in space aren’t straight up cool? And that’s without even considering what we use them for. Where would we be without the internet, or GPS? Probably outdoors, and lost.
But satellites have utility that extends beyond the realm of kittens in top hats, as Dr. Nathalie Pettorelli from the London Zoological Society knows. She gave a memorable seminar on the use of satellites in biological research, single handedly doubling the number of items on my “Reasons I Want a Satellite” list.

1. Vegetation Surveys
The point of owning a satellite – apart from the prestige and party scene – is being able to do cool stuff with it. Unfortunately, most satellites don’t have the kind of firepower necessary to ransom the Earth, but they do have cameras, and there are a lot of uses for a camera in space. For the botanically-minded, vegetation surveys are one possibility.
Working out what trees and how many are in a particular place can be time consuming. You have to go out, pick survey plots, count and identify trees, often in very remote locations miles from the nearest western toilet. Not when you survey via satellite.
To conduct a satellite survey you simply wait until your satellite is overhead, then take pictures. The scale of these pictures can vary from a few tens of centimetres to metres, and once you have them you’ve saved yourself a lot of time, money, and effort. Then you can use your satellite images to spot illegal logging of rainforest, or examine how storms affect mangroves. Best of all, your camera isn’t restricted to what your eye sees. By examining the relative amounts of red and near infrared light reflected from the Earth’s surface, you can determine the “greenness” of vegetation, assess its seasonality, and judge its composition, all of which is vital for finding habitat for reintroduction programs.

2. Multi-Scale Ecology
Two of the seminars we’ve enjoyed have been about ecological scales. Unfortunately, it’s often difficult to obtain data on the largest scales, so unless you’re willing to put in obscene amounts of work and time, you’re not going to get any meaningful information. That is, unless you have a satellite.
Once again satellites trump doing things by hand. They can survey large areas much more quickly and many times more than even the most dedicated research team, and depending on what you’re looking for can provide highly valuable information. Want to assess eutrophication of freshwater? Check out the “greenness” of the lake’s phytoplankton. Want to determine the clarity of the water? Use lasers emission and work out the absorbance rate. If the phenomenon you want to study affects light absorption or reflection in any way, then satellites should be up to the task.

3. Counting Penguins
By now you’ve noticed the theme of my satellite-based projects. When it involves very large – or just difficult to reach – areas, then you can probably do it faster by satellite. But satellite projects aren’t just limited to plants and ecosystems. They can be just as useful for surveying animals over large, hard to reach areas, and there are few areas as large or hard to reach as Antarctica.
If you’ve ever wondered how many penguins are at the south pole, you’re not the only one. We’ve all pondered the number of well dressed birds that manage to carve out a stylish existence on the ice. One research team, however, decided to do something about it, and – you guessed it – they did it with satellites.
The idea is brilliant in its simplicity: take photos of penguin guano from space. Yes, that’s right: millions of euros of equipment used to photograph poo. From space. That has just the bizarre and disgusting ring to it that marks a good zoological study. Outlandish as it may sound, using this method the team discovered 10 new penguin colonies in Antarctica! What’s more, using satellites operating at a finer scale, other researchers were even able to estimate the sizes of penguin colonies!
To sum up, satellites and biological research go hand in hand. No longer is space the privileged realm of the physicist looking down on the (erroneously) perceived softer scientists. Zoologists, botanists, and ecologists have carved out a territory in orbit. There are a lot of questions we’ve yet to face, but the answers are out there.

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Walking on Tenderfoot

Gina McLoughlin

Being an avid follower of a blog called What’s in John’s Freezer naturally I was extremely excited when Professor John Hutchinson from the Royal Veterinary College, London came to give us a seminar. He gave a very interesting and entertaining talk on 6-toed elephants and knobbly-kneed birds: Case studies in the evolution of limb sesamoid bones. Hutchinson explained to us about his recent research into the tiny sesamoid bones, such as the patella, that are found in the limbs of many animals. Sesamoid bones are small “bits” of bone that are generally located in a tendon or near a joint (Sarin et. al., 1999). Their function is not fully understood but it is hypothesized that they may play a role in changing the direction of muscle forces in a limb or may play a role in protecting the tendons.

A very interesting case of such sesamoid bones, which Hutchinson talked about, is found in elephant feet. Elephants, like humans have 5 toes but unlike humans they stand on their tiptoes and have a hoof-like sole. They have a fat pad at the heel of their foot, which acts as a cushion and supports the toes. It is here, buried deep in the fat tissue that the pre-digit bones are found. Hutchinson explained they are like a 6th toe that can be found in both the front and the back feet. The bones are known as the prepollux and prehallux and they connect to the real toes just under where our thumb is (Hutchinson et. al., 2011). They are cartilaginous for most of the elephant’s life, but do eventually ossify when the elephant gets older. Again, the function of these sesamoid bones in the elephant is not fully understood although Hutchinson proposed they could be used as levers for extra support due to the weight of the elephants. Another hypothesis is that instead of developing a single hoof, like in a horse, the elephants use this pre-digit to distribute their weight more evenly on each foot (Hutchinson et. al., 2011). However, these pre-digits have been observed in other animals and have different functions than what they have in the elephant. Most surprisingly to me was that they are found in pandas. Here, they are used for grasping bamboos while eating, kind of like a false thumb. Their 5 fingers close over the false thumb, which has evolved by enlarging the radial sesamoid and functions as an opposable thumb (Endo et. al., 1999).

A thought provoking point that Hutchinson made in his seminar was how do such small bones cause big problems in animals. These bones can cause such big problems that it almost makes big animals appear very fragile. For example, elephants in zoo need to have their feet very well looked after to prevent them from going lame. Hutchinson explained that if an elephant goes lame due to a sesamoid bone problem it is more than likely that the elephant will be dead in approximately 5 years time, as it is very hard to fix and they are in a lot of pain. Likewise, giraffes need a lot of hoof-care to prevent their sesamoid bones from dissolving completely. This would cause the giraffe to go lame and prevent them from thriving.

A more common animal example of a sesamoid injury that I find very interesting, and an area where more research needs to be carried out, is in horses. The sesamoid bones from which most injuries occur are located in the lower limb, at the back of the fetlock joints in the both the fore and hind limbs (Figure 1). In horses it is hypothesized that these bones are used as a pulley for the suspensory ligament as it passes over the back of the fetlock joint. They are very important in the mechanical functioning of the fetlock joint. Horses in competitive sports, such as show jumping and racing frequently suffer from sesamoiditis (Spike-Pierce & Bramlage, 2003). This is commonly caused by heavy loading on the limbs and over-flexion of the fetlock joint, which can result in the sesamoid ligament tearing. This extra pressure can lead to increased internal bone stress, which may lead to a fracture of the sesamoid bones. Faulty blood flow to the bone can be a result of this damage and demineralization of the bone can occur.

Figure 1: Labeled diagram of an equine lower limb showing the fetlock joint and sesmoid bones.
Figure 1: Labeled diagram of an equine lower limb showing the fetlock joint and sesmoid bones.

Thankfully, most cases of sesamoiditis can be treated with anti-inflammatory medicine, cold therapy and support strapping or bandaging. However, in more serious cases where a fracture has occurred the horse may never return to the top of their sport due to the damage (Kamm et. al., 2011). Once a sesamoid bone is damaged they are very difficult to cure because every time the animal walks they put more pressure on the bone, preventing it from healing.

By the end of the seminar I was amazed that such small bones could be so interesting. I would never have though that these tiny bones could be the cause of such big problems not only in competitive horses, but also in large animals such as elephants. Overall, I really enjoyed Hutchinson’s talk. I thought he was a very good speaker and I would now possibly consider doing some research in this area myself.

 

How to get the benefits of mobility – even when your movement is constrained

acadm_mobil

There are a long list of reasons why mobility in an academic career is considered highly desirable, both by individuals and the institutions which fund them. Scientists move around to take up jobs in a tight and international job market, communicate their work to the wider scientific community, work with new people, learn new techniques, strengthen networks or because they like adventure. However, there are many excellent scientists who are constrained in various ways to be less mobile than they would like or than would be good for their careers .

I have always loved to travel, and after almost 15 years of moving around for jobs, fieldwork, conferences and adventure, my own constraints arrived in the guise of two adorable children. My kids have taught me a lot about the benefits of a more sedentary life but I still have itchy feet and the desire to interact with colleagues internationally. This period in my life led me for the first time to really think about what it is about mobility that is of benefit and how to achieve that while staying at home.

Constraints are costly. Some constraints can be overcome by providing resources or altering institutional structures.  Other constraints are personal or philosophical and might best be considered as hard constraints (unchangeable). Common constraints include personal family situation such as partner’s career and caring responsibilities for children, parents or friends and personal mental and physical health. The costs of mobility include financial costs, disruption, adaptation to a new scientific and/or social culture, language barriers and leaving a productive group. For all of these reasons scientists may be temporarily or permanently constrained from being able to physically move locations for work reasons.

It makes sense to me to have a range of strategies for getting the benefits while minimizing the costs of mobility. Grant applications sometimes explicitly or implicitly require or evaluate mobility as a proxy for the benefits obtained. If you have had your mobility constrained it might be useful for you in grant applications to articulate what strategies you have used to get the benefits of mobility despite your constraints.

First determine exactly what your constraints are and exactly what activities are constrained. For example do you care for young children which prevents you from traveling overnight for a period of time? Do you need to be in close proximity to healthcare? Determine the boundaries of your constraints. Next estimate the benefits of mobility to your particular situation – the benefits of mobility might be largest if you are currently in a small, relatively unproductive group with limited resources and the benefits of mobility might be much smaller if you are already in a large, productive, well connected (lots of incoming visitors) group.

Determine the costs of mobility: financial, social, environmental and to your productivity. Costs may be larger as you progress through your career but are also more likely to be defrayed through relocation expenses paid or broader networks of colleagues gained. Perhaps for you the costs outweigh the benefits as you are already in the ideal group and don’t want to move because it’s working extremely well for you. Great, but be open minded about additional opportunities to gain additional benefits at low cost.

It is important to recognize that a case for gaining the benefits of mobility may be easier to make with a broad view of mobility. Mobility can be short- or long-term and can be inter-institutional, cross-sectoral, national, international or intercontinental in scale. Many benefits could be gained from doing internships in a different institution or industry but remaining in the same city for example. Below are a few strategies that might be helpful, not all will be possible depending on your situation.

Find a position in a group in your location which is large, productive & well connected. You don’t necessarily have to be employed by them if you can negotiate a day or two a week as a visitor there.

Make use of technology for virtual collaboration – Skype, Adobe Connect, Google hangouts, dropbox, telephone, email, twitter, blogs, Mendeley, Git etc. These require a bit of work to ensure efficacy and avoid the “out of sight, out of mind” problem of not bumping into collaborators in the hallway.

Attend meetings in virtual mode by accepting to give talks but ask to be able to give a video presentation, this is most effective if you can also take part in the discussion afterwards via video conferencing. Ask the organisers to record and send you the video afterwards so you can re-use it. Use twitter to keep up with what’s happening at the meeting if you can’t attend. Tweet and/or blog for others if you can attend in person. I was immensely grateful for the tweeters and bloggers when I was at home on maternity leave and couldn’t attend “my” meetings for a few years.

Attend conferences and extend your network, make sure you gain active collaboration from conference meetings. Be part of international working groups, engage or initiate global research networks.

Develop relationships with potential collaborators via social media, name recognition is important and people will be more inclined to work with you if they have interacted with you positively via twitter/facebook/whatever young people do these days.

Invite visitors to your institution. Find out if there are funds available to help visitors pay for their visit (e.g. visiting fellowships, travel funds if they give a seminar), help visitors apply for these. Paying for a few extra days of accommodation for a visitor if their flight is already covered can be a cost effective way to encourage more interaction. Offer to let them stay at your house. Parasitise sabbatical visitors to other close-by institutions by inviting them to your institution for a day/week/month.

Apply for grants to fund workshops which enable you to run working groups at your own institution and which fund the travel & accommodation of visitors.

If you get invited to present or visit and can’t do it, ask if you can send your student/post-doc/colleague in your place. Make sure you follow up with your proxy to ensure you learn what they’ve learned and if there are outputs of the visit that you can also contribute to.

Lobby funding organisations and institutions to allow your mobility constraints to be taken into account in funding applications and promotion cases (e.g. caring for family members).

Lobby funding bodies and employers to directly fund expenses associated with travel (e.g. extra care for dependents).

Record on your portfolio all invitations to speak/present/take part, even if you have to turn them down as these are useful indicators of your profile and measures of esteem.

Be creative in finding ways to relax your constraints, perhaps you can pay for a grandparent to travel and accompany you on a conference trip as extra child support, perhaps you can take your baby with you to the conference and rely on them to stay quiet enough for you to give a talk with them asleep in a sling, or pass them onto trusted colleagues willing to babysit for half an hour. I took my 2 month old to a workshop, pictured here with Antoine Guisan, where she got passed around several academic alloparents to enable me to contribute to this paper. Perhaps you can afford extra childcare by living frugally while travelling. Be flexible.

guisan

Ask conference organisers to make provisions if you need to bring your kid/s with you. For example have a family room with the talks screened via video-conferencing/skype or provide crèche facilities.

Discuss with your partner possibilities for one or both of you to take up part-time work or for your partner to become primary home carer. Move closer to extended family, especially if they are willing to help with caring responsibilities.

Finally, for funders, conference organisers and others who rely on the ability and willingness of scientists to pack their bags and jump on a plane at a moment’s notice, spare a thought for those who are constrained. Provide alternative arrangements for child-care at meetings, provide opportunities for video conferencing, encourage participation and consider evaluating CVs based on what benefits have been gained, not just how many times someone has moved.

Author: Yvonne Buckley, buckleyy[at]tcd.ie, @y_buckley

Image Source

Biodiversity face off

Between the 1st and 2nd of May several members of the Trinity Centre for Biodiversity Research got their game faces on for the inaugural Intervarsity BioBlitz Challenge. For the first time the Trinity fox and co were pitted against the best biodiversity on offer from the DCU, NUI Galway and UCC campuses.

The stakes were high but the goal was simple; identify more species on campus then any other college in a 24 hour period and become the first college biodiversity champion of Ireland!

Kicking off Trinity’s effort to win the championship the birdwatchers were up bright and early to catch the dawn course. With 19 species identified it was the Sparrow hawk that caught the eye (but evaded the camera lens) of our inner city campus birds.

While the birders were digesting their findings some early morning pond dipping was throwing up its own surprises with a three-spined stickleback found in what looked an inhospitable pool out the back of the Zoology Department.

The unlikely source of our only campus fish, the three-spined stickleback
The unlikely source of our only campus fish, the three-spined stickleback

Meanwhile in the more hospitable setting of Trinity’s own little secret garden some black ants were having a midday honeydew snack from their aphid herd during our plant identification walk.

The ant in focus can be seen feeding on the sugary secretions of the aphid, which in return for feeding the ants gains protection.
The ant in focus is feeding on sugary secretions from the aphid, which benefits from the ants’ protection in return.

Although many of the 32 species of invertebrates were found amongst the plants and pools, it was in the nooks and crannies of various building walls that Trinity’s diversity of arachnids, such as the snakes back spider, were found to reside.

Segrestria senoculata spider awaiting unsuspecting passers-by
Segrestria senoculata spider awaiting unsuspecting passers-by

While many volunteers were out rummaging in the leaf litter, Rachel Kavanagh was busy coordinating efforts at the central hub in the Science Gallery. There were also some inquisitive guests from St. Mary’s Boys school learning about pollinators with Green Bee Education.

Students from St. Mary’s Boys school building solitary bee shelters.
Students from St. Mary’s Boys school building solitary bee shelters.

As the day passed-by collecting and identifying specimens the deadline quickly approached and results were coming in. Galway won with a massive 581 species, with Cork on 451 leaving the race to avoid the wooden spoon between the Dublin Campuses. Unfortunately despite the heroic efforts of everyone, especially the botanists who identified 245 species of plants, Trinity could not avoid the dubious wooden spoon award, finishing with 346 and losing by just 27 species.

However while we didn’t win their was plenty of consolation prizes to be found as @EndangeredDAVE left some postcards and paintings of endangered Irish species in various spots around campus.

One of the many beautiful pictures distributed around campus by @EndangeredDave.
One of the many beautiful pictures distributed around campus by @EndangeredDave.

With an impressive 346 species recorded in an inner city campus and an incredible increase on previous years (16 species in 2012 and 126 species in 2013) TCD’s form is only on the up with the Trinity fox looking to be the top dog in next year’s event.

Look out for bioblitz events near you this weekend!

Author and Images: Kevin Healy, healyke[at]tcd.ie, @healyke

Mooching in Madagascar

I recently returned from a short stint of fieldwork in Madagascar. The purpose of our trip was to run some behavioural tests of echolocation in tenrecs but things didn’t exactly go according to plan. Therefore we had plenty of time to explore and experience some of the wonders of the 8th continent.

Here’s a few of our wildlife highlights…

Shower lizard
Our friend from the shower
Spider webs
Enormous spider webs which span an entire river bed!
Moth case
Case from a bagworm moth
Indri
Spot the Indri (like four year olds in panda suits..)
Tree frog
What a poser
Chameleon
Just hanging around
Camouflaged frog
Spot the frog
Red bellied lemurs
Inquisitive red bellied lemurs (Eulemur rubriventer)
Hemicentetes semispinosus
Tenrec in a bucket! Hemicentetes semispinosus

 Author and Images: Sive Finlay, sfinlay[at]tcd.ie, @SiveFinlay

Bumblebees are not deterred by ecologically relevant concentrations of nectar toxins

800px-Bumble-bee_on_Rhododendron

In a previous blog post I wrote about my work on “toxic nectar.”  This paradoxical phenomenon occurs when potentially deterrent or toxic plant secondary compounds, usually associated with defense against herbivores, are found in floral nectar rewards.  Throughout my PhD I’ve spent countless hours in the lab performing experiments on toxic nectar, discussed this work at Nerd Club, and presented it at conferences.  After what seems like an awfully long time, our first article on nectar toxins has been published in the Journal of Experimental Biology.  Here I want to describe what I think are the most exciting findings of the study, and also talk about how this work came to be part of my PhD.

When I first started my PhD I had what seemed like a never-ending list of questions about nectar toxins: do they impact plant fitness?  What about pollinator survival?  Are there sublethal costs to pollinators that ingest nectar toxins? But before we could tackle these bigger-picture concepts, we kept on coming back to a very simple question: are bees deterred by naturally occurring concentrations of secondary compounds in floral nectar?

We know that many plant secondary compounds, such as alkaloids, phenolics, and terpenes, play a role in deterring herbivores form consuming plant tissues, and that’s why toxic nectar is such a paradox.  Why would plants have deterrent compounds in a tissue that is meant to act as a reward for pollinating flower-visitors?  Nectar secondary compounds, however, tend to occur at much lower concentrations than those found in leaf or floral tissues. Previous work found that whether or not bees will forage on artificial nectar containing secondary compounds depends on ecological context, i.e. the availability of other food sources.  However most work on this subject focuses on only one compound (gelsemine) and tests concentrations that are well above those found in floral nectar.

One might hypothesize that secondary compounds at nectar-relevant concentrations should not be deterrent to pollinators.  If nectar toxins do deter legitimate pollinators, plant pollination and hence reproductive success could suffer, leading to selection for lower concentrations of nectar compounds.  In addition, the direct impacts of nectar toxins on pollinators are still understudied; deterrence behavior might indicate a cost in terms of health or fitness for the pollinators.  So we were convinced it was well worth determining deterrence thresholds for several of the most common/popular nectar toxins, and comparing these thresholds to nectar-relevant concentrations, but how did we do it?

The experimental design was very simple (my favorite kind!); we used an economically and ecologically important pollinator, Bombus terrestris, in a series of controlled, paired laboratory bioassays.  In each assay, we offered bees two solutions of identical sugar content, one containing a secondary compound of interest and one without it.  We repeated this 24-hour assay at a range of concentrations that included the nectar relevant dosage for each compound we tested.  The deterrence threshold was determined when bumblebees significantly preferred the sucrose solution over the sucrose solution containing the compound.  We also measured the total food consumed and bumblebee survival.  I spent a lot of time in the laboratory and the bee room, weighing feeding tubes and counting dead bees; I’m not going to lie, I may have succumbed to talking to my bees now and again.  It gets lonely in the lab!  It was all worth it in the end though, because what we found was pretty interesting.

IMG_0038 (1)
These were my friends for many hours!

Our experiments showed that bumblebees are actually rather bad at detecting nectar toxins. The most deterrent compound was the alkaloid quinine, which was avoided at concentrations as low as 0.01 mM.  All the other compounds we tested (caffeine, nicotine, amygdalin, and grayanotoxin) had deterrence thresholds 7-60 times greater than the concentration range naturally found in nectar.  Previous work on the honeybee found that it too has poor acuity for the detection of nectar toxins, especially compared to insects in the orders Diptera and Lepidtopera.  So why is it that social generalist bee species are relatively insensitive to the plant secondary compounds in their food?  One hypothesis we highlighted in the discussion is that the relationship between bees and plants is largely mutualistic, as opposed to the antagonist interactions between plants and herbivores.  There may not be strong enough selection pressure on bees to develop more sensitive gustatory receptors, especially because in eusocial bee species, individual bees are the consumers, but selection pressures act on the colony as the reproductive unit.

For decades, researchers of plant-animal interactions have been asking how and why toxic nectar evolved and is maintained in plant populations.  Our work helps us to better understand the functional significance of toxic nectar.  If legitimate pollinators fail to be deterred by nectar compounds at low concentrations, the plant is less likely to suffer from reduced pollination.  This trait therefore may be maintained in plant populations, especially if it confers some sort of fitness advantage to the plant.  What kind of fitness advantage could these compounds provide you ask?  There are a plethora of possibilities, including antimicrobial resistance and selection against more sensitive nectar robbers or thieves.  Possibly the presence of the compounds in nectar is simply a consequence of defense of other plant tissues.  The results from our study, however, suggest that these other factors affecting nectar secretion and production are more likely to select for the production of toxins in nectar of bee pollinated plants, rather than pollinator preference.

Check the paper for more details and to read the whole story!

Author: Erin Jo Tiedeken, tiedekee[at]tcd.ie, @EJTiedeken

Images: Wikicommons and E.J. Tiedeken

How Do We Solve A Problem Like Invasive Species?

There are many threats to our environmental security: climate change, habitat loss and degradation, pollution. All are damaging the environment and impacting on our long-term survival. One threat that seems to have been often overlooked by the public, however, is the effect of invasive species.

Invasive species are non-native species that adversely affect the invaded region. Not every non-native species becomes invasive: some fail to establish while others may establish but at sufficiently low population densities to have minimal impact on their new home. But a few species will find themselves so at home in their new land that their populations explode and, due to a lack of any predators adapted to deal with them, their populations remain unchecked.

There are many famous examples of invasive species: the Burmese python in Florida, rabbits and cane toads in Australia, the grey squirrel in the UK and Ireland. Attempts to control all these species have been made over the years, though none have successfully managed to completely eradicate them.

invasive rabbits
Invasive rabbits!

While much of the media is focused on local invasive species, the greatest impacts are often found not in large inhabited countries but on small, isolated islands. You may be wondering how invasive species can reach small, isolated islands but humankind’s reach has been vast and in the days of shipwrecks and long voyages sailors often found themselves on shores never-before touched by man. When they came ashore so too did stowaways in the form of rats. Some species were even purposefully introduced in order to provide food for victims of shipwrecks. In these ways species including rats, cats, rabbits, pigs, sheep and reindeer have found their way to islands all around the world, including those in the sub-Antarctic.

The impacts of these species have been great and varied. Many islands are home to ground-nesting seabirds and their eggs and chicks are extremely vulnerable to predation by rats and cats while their nesting sites can be damaged by rabbits and larger mammals. Grazing also impacts on the islands, leading to habitat loss and soil erosion. As seabird numbers have fallen due to interactions with fishing gear, harvesting for food and though the effects of invasive species on their breeding success, attempts have been made to rid islands of these now unwelcome interlopers.

The effects have been mixed. Some attempts have been hugely successful. The most successful is arguably that of Campbell Island, a sub-Antarctic island south of New Zealand. It had a succession of eradications starting in the 1980s that culminated in the early 2000s with the eradication of rats across the entirety of its 113 square kilometres. This was at the time the largest area ever cleared of rats. I remember being told by a lecturer, though this may be apocryphal, that there was a conference going on at the time where people were explaining why it was impossible to eradicate rats from large islands at the very same time that this eradication programme was coming to a successful close.

Campbell Island
Campbell Island

Some attempts have not been so successful and they highlight the importance of good management and understanding of food web interactions. I believe, or at least I certainly hope, that the following example is the most extreme case to date. Without further ado, I present to you the case of Macquarie Island.

Macquarie Island is a sub-Antarctic island between Australia and New Zealand. It is home to elephant seals, three species of fur seal and thirteen species of seabirds including penguins, petrels and albatrosses. Rats, mice and cats were introduced by sealers in the early 1800s and rabbits were introduced in the 1870s. Both the cats and the rabbits have had devastating impacts on the seabird colonies. Rabbits caused erosion through their burrowing and cropping of the vegetation while the rats ate young chicks. The combination of predation and habitat destruction are thought to be responsible for extinction of the two endemic species on the island, the Macquarie Island parakeet and the Macquarie Island rail.

MacquarieIsland
Macquarie Island

By the 1980s the habitat destruction was becoming significant and a decision was made to control the rabbits through the introduction of myxomatosis which decimated the rabbit population. This had an unexpected impact on the cats: it turned out the cats had been predating on the rabbits and used them as their main food source so when the rabbits disappeared the cats turned their attention to seabird chicks. Once this was realised the need to control the cat population was quickly recognised.

A cat eradication programme began in 1985 and by 1999 the last cat on the island was killed. You would be forgiven for thinking that this is the end of the story: rabbits controlled, cats switched their diet, the mistake is recognised, cats are controlled, and now the seabirds can live happily ever after. . . If only it were that simple.

The rabbit population began to re-establish itself. It increased rapidly and by 2006 was back to pre-control levels. The rabbits were devastating the island In 2006 a large landslip, caused by erosion by rabbits, partly destroyed a penguin colony.

It was clear that something had to be done and in 2007 the Australian Government announced their intention to eradicate Macquarie of invasive rabbits and rodents (rats and mice) at a cost of A$25 million. The need for this eradication was highlighted in a 2009 paper by Dana Bergstrom and colleagues from the Australian Antarctic Division. They showed the full effects of the cat eradication programme on the rabbit population and the terrible consequences to the vegetation of the island. Their report highlighted the need for integrated eradication programmes that examine the whole ecosystem and predict and plan for unintended consequences of the removal of invasive species.

The story could have ended there, a costly mistake both in ecological and economic terms. It is where the story ended for me until I started researching this piece. It turns out that there is a surprisingly happy ending as earlier this month the Australian and Tasmanian governments announced that Macquarie was officially pest free following the success of their eradication programme. This success means that Macquarie now beats Campbell Island as the largest island cleared of pests, an achievement that is of global significance. It’s an incredible feat, one I feared would be impossible. Though it will still take time for Macquarie to fully recover from the effects of more than 200 years of alien inhabitants, it now has that time. Finally Macquarie is home only to the birds and seals; a sub-Antarctic paradise has been restored.

King pengiiuns (1)

Author: Sarah Hearne, hearnes[at]tcd.ie, @SarahVHearne

Images: Wikicommons

 

Kakapo Conservation

In centuries past, if you were to go into the hills of New Zealand on a summer’s night you may have heard a strange noise; a honking boom that resonated all around you. After 20 or 30 cycles of this boom you’d hear a high-pitched rasping ‘ching’ sound. This boom and rasp would come from all around you and would be heard all night, night after night for at least two months. This is the sound of kakapo males trying to attract a mate.

Kakapo 1

Kakapos, (Strigops habroptilus) are nocturnal, flightless parrots. They are found exclusively in New Zealand and while they were once common across all three main islands of New Zealand, they are now restricted a few small offshore islands. They are unique birds in a number of ways. They are the only flightless parrot and, probably as a result of this, are also the world’s heaviest parrot. They are also the only parrot to chose mates using the lek mating system.

Lek mating involves males displaying for the females and the female picking “the best” male. It’s a winner-take-all scenario as different females usually chose the same male. If you’re the chosen male then it’s a successful breeding season but if you’re not then you go home empty-handed. Males in lek systems typically take no part in the rearing of offspring and kakapo are no different.

Kakapo use an ‘exploded’ lek system, where males are generally out of sight of each other (the more traditional system has all males within eyeshot). During the summer months they go to hilltops and ridges and create a bowl in the earth in which they sit. These bowls are thought to help amplify their booms. They may have several bowls which are linked by tracks created by removing vegetation [1]. They then inflate a sac in their thorax and create the booms and chings. The booms are to attract a female and the ‘chings’ help her to find him as the booms can travel up to 5km while the ‘chings’ are more locatable due to their high frequency. Once a female has been attracted to a particular male and enters his view he performs a dance for her after which they mate

The female lays between one and four eggs in a makeshift burrow, either in cavities such as in those in trees or under vegetation. The eggs hatch within a month and she then has to look after the chicks for up to six months, though they leave the nest after about three months.

Kakapo 2

Kakapo only reach maturity after the age of about 5 and females only start breeding around the age of 10 [2]. Females reproduce every few years after a masting event. Masts are where plants, in this case the rimu tree, produce large amounts of fruit simultaneously, overwhelming the local wildlife with food. Even with the increased food not every female is able to get fit enough to exert the energetic costs associated with reproduction  and so not all females will breed in a given year [3].

As I explained in a previous blogpost, New Zealand avifauna has been threatened by the introduction of predators. Given their slow reproductive rate and terrestrial lifestyle they are particularly vulnerable to predation and have been pushed to the edge of extinction. By the 1970s less than 20 were known to exist and all were males. It seemed that the kakapo were doomed. But in 1977 a female was found on Stewart Island and from that one female a miracle has occurred and the population currently stands at 130 birds.

This success has been hard won. Part of the problem is that so little is known about the birds that trying to get them to breed successfully has been challenging. Added to that the long life-span (it’s not known how long the birds live but it appears to be decades) and the slow reproductive rate means that conservation efforts are going to take decades if not centuries before it is known whether or not they have been successful.

One stumbling block that was hit was an unintended consequence of trying to increase the number of breeding females. Females only breed when they reach a minimum weight. In order to increase the number of breeding females in a given year they were given additional, or supplementary, food. The unintended consequence was that this resulted in more males than females being reared.

Kakapo 3

The Trivers-Willard hypothesis predicts that females will produce more males when they are in good condition and more females when they are in poor condition. The idea is based on the costs and benefits of each offspring in terms of her ability to transmit her genes to future generations. In polygynous systems a female will be able to mate with a male regardless of her fitness: the males don’t care whether the females are only just fit enough to reproduce or are at peak condition. But in the same system only the fittest males can beat their rivals and gain access to females. The fitness of a female will affect the fitness of her offspring so if she’s not particularly fit it is in her interests to produce females whose future fitness will not significantly affect their reproductive potential. If she’s at peak fitness, however, it’s in her interests to produce males who are more likely to be the dominant male and be able to beat rivals to females.

You may be able to see the unintended consequences already. The supplementary food pushed all the females into top condition and they all produced males. Experimental supplementary feeding at different levels was used to confirm the hypothesis and found to be true [3]. As a result, the supplementary feeding program was adjusted so that females at fed to a level of fitness where they could successfully reproduce but are not so fit that they produce only males. It has been so successful that from the highly skewed sex ratio at the start of the programme it is now approaching parity with 70 males and 60 females.

The conservation program still has a long way to go before kakapo can be considered to be saved. It may be that disease (highly possible given the low genetic diversity) or a series of unfortunate events reduces the population to a level from which it cannot recover. In some sense the birds are living on borrowed time, but despite the uncertainty of success, the effort is well worth it. These birds are unique in the world and are worthy of our care and conservation. Long may their ‘borrowed time’ continue.

Kakapo 4
Don Merton, saviour of the kakapo, with Richard Henry, one of the more famous kakapo

 

Author: Sarah Hearne, hearnes[at]tcd.ie, @SarahVHearne

Image Sources: Wikicommons

References:

1) Merton, D. V et al. (1984)

2) Eason, D. K. et al. (2006)

3) Clout, M. N. et al. (2002)

 

Flatland

elephant rock

Why are there no elephants in the mountains?

Well, mainly because it’s costly to climb when you’re an animal of that size. A previous study estimated that a 4 tonne elephant would have to eat for 30 minutes to compensate for a 100m climb. Ideas man Graeme Ruxton and his co-author David Wilkinson develop this further in their new paper. They ask whether avoidance of hilly areas is to be expected in general for animals of a large mass such as the sauropods. These are the long-necked dinosaurs that were the largest terrestrial animals that ever existed. Some of the upper mass estimates of, albeit poorly described, species are over 100 tonnes! Using simple scaling relationships relating to the energetics of movement, food intake etc. Ruxton and Wilkinson show that as a herbivore increases in size the fraction of time spent eating to balance the cost of climbing will increase.  In the case of sauropods we can look to the fossil record for support and it does show the creatures preferred flat environments such as fluvial plains.  Their footprints and nesting sites are often preserved in these areas. Of course, energetic concerns aren’t the only issue stopping these animals from populating the hills. The danger of falling would be much higher on a friable surface and the bigger you are…

Any thoughts of regaining your energy on the way down after a costly ascent can be dispensed with. An animal must expend energy to control the rate of descent especially to avoid falling. One benefit of being large is that you have energy reserves so it is possible to travel into the hills if absolutely necessary but these forays would be infrequent.

This result suggests steep areas should be depauperate with respect to larger herbivores. We could imagine highland islands of smaller herbivores alongside plants which are free from the pressures of huge plant-eaters. The conclusion of the paper asks us to explore extant ecosystems for such a pattern. This could be extended to Mesozoic ecosystems. Perhaps there would be an ontogenetic niche shift in the sauropods, moving from hilly areas to the flatlands as they developed.

Author: Adam Kane, kanead[at]tcd.ie, @P1ZPalu

Image Source: Wikicommons

Silence of the Tenrecs

Microgale cowani

I’ve been studying tenrecs for almost two years. I’ve read about them, watched video clips and handled hundreds of dead specimens. However, within that time I only met two live individuals, both of which were captive zoo animals. That’s all changed. I’m now well acquainted with a variety of tenrec critters. It turns out they’re a quiet bunch.

Just slightly excited to be holding a live tenrec!
Just slightly excited to be holding a live tenrec!

My supervisor, Natalie, and I spent two weeks in Madagascar working with a research team from the Vahatra Association led by Steve Goodman. The purpose of their trip was to conduct a disease transmission study in bats and small terrestrial mammals study at Ambohitantely Special Reserve, a protected, upland native forest north west of Antananarivo.

Ambohitantely forest surrounded by central plateau grassland
Looking down onto Ambohitantely forest; not a bad place to work…

We tagged along on the trip to run behavioural experiments to test whether there’s evidence for echolocation in the shrew-type (Microgale) tenrecs. Armed with a bat detector and an adjustable maze, my plan was to record the tenrecs’ calls as they move through their environment in search of a worm food reward at the end of the maze.

Our “experimental chamber”; the maze box (covered with material in the bottom right of the picture) set up in a shower cubicle!

I had envisaged many potential problems with the experiment. How would we be able to filter out interesting noises from background sounds? Would the noise of the animals moving around mask out the true vocalisations? I didn’t, however, foresee the problem with which we were faced; they didn’t make any noise whatsoever, zilch, not a peep.

Pockets bulging with tenrecs!

We tried multiple methods to coax some sound out of the furry creatures. The animals were kept warm in Natalie’s increasingly bulging coat pockets. We tried to entice the animals using juicy worms as proverbial carrots. We experimented with placing pairs of individuals in the box at the same time hoping to overhear some  tenrec chat. We also eliminated technical faults as a possible cause by testing out my detector on the bats flying around camp at night. All to no avail.

Microgale dobsoni; "I'm not going to produce any sound and you can't make me"
Microgale dobsoni; “I don’t want to produce any sound and you can’t make me”

I think they were holding out on us. The other, more experienced field researchers had heard tenrecs squeaking while foraging. The previous work on echolocation in tenrecs which inspired my experiments includes recordings of one species of Microgale so the animals are certainly not mute. I think our empty sound files are an unfortunate consequence of our experimental protocol. Existing research on possible echolocation in shrews and tenrecs used captive animals under highly controlled experimental conditions. We, however, were constrained by time and resources to an artificial experimental set up so it’s unfortunate but not entirely surprising that things didn’t go according to plan.

Still, the trip was far from wasted. Studying and observing living animals is just a tad more exciting than their museum counterparts and I now have enough pictures of tenrecs to last for a lifetime of presentations. We met some extremely interesting and knowledgeable researchers and we had the opportunity to work in a remote, beautiful and exotic place.

Furthermore, our failed experiments left time to go and explore other areas as tourists; expect our encounters with Indri, mouse lemurs, chameleons and enormous spiders to be coming soon…

Author and Images: Sive Finlay, sfinlay[at]tcd.ie, @SiveFinlay