Some new papers have come out from both the Pied Babbler Project and the Arabian Babbler Project. I’ve put the abstracts and links below. This is a very quick blog, basically trying to get people to read these two great papers.
 
The first is Sabrina Engesser’s work into vocal communication and syntax in pied babblers. Using observations and playback experiments, Sabrina has been able to show that the order in which alarm and mobbing calls are given is highly important for these group living birds. Syntax is something that humans use and has been observed in primates but never in birds. This ground breaking work is important for understand how language may have evolved and how widespread some of the components of our communication are in the natural world.
 
The second is from Oded Keynan, this time looking at population dynamics instead of his normal social learning research. This new work shows that the group living Arabian babblers suffer the population and group effects of the Allee effect. Larger groups are better able to rear young and persist than smaller groups, and this isn’t just on a group level but also denser populations do better as well. Interestingly, however, immigration and emigration don’t really have an effect.
 
I hope you have a read, because they’re two great bits of research.
 
Meaningful call combinations and compositional processing in the southern pied babbler. PNAS
Language’s expressive power is largely attributable to its compositionality: meaningful words are combined into larger/higher-order structures with derived meaning. Despite its importance, little is known regarding the evolutionary origins and emergence of this syntactic ability. Although previous research has shown a rudimentary capability to combine meaningful calls in primates, because of a scarcity of comparative data, it is unclear to what extent analog forms might also exist outside of primates. Here, we address this ambiguity and provide evidence for rudimentary compositionality in the discrete vocal system of a social passerine, the pied babbler (Turdoides bicolor). Natural observations and predator presentations revealed that babblers produce acoustically distinct alert calls in response to close, low-urgency threats and recruitment calls when recruiting group members during locomotion. On encountering terrestrial predators, both vocalizations are combined into a “mobbing sequence,” potentially to recruit group members in a dangerous situation. To investigate whether babblers process the sequence in a compositional way, we conducted systematic experiments, playing back the individual calls in isolation as well as naturally occurring and artificial sequences. Babblers reacted most strongly to mobbing sequence playbacks, showing a greater attentiveness and a quicker approach to the loudspeaker, compared with individual calls or control sequences. We conclude that the sequence constitutes a compositional structure, communicating information on both the context and the requested action. Our work supports previous research suggesting combinatoriality as a viable mechanism to increase communicative output and indicates that the ability to combine and process meaningful vocal structures, a basic syntax, may be more widespread than previously thought.
 
 
Component, group and demographic Allee effects in a cooperatively breeding bird species, the Arabian babbler (Turdoides squamiceps). Oecologia
In population dynamics, inverse density dependence can be manifested by individual fitness traits (component Allee effects), and population-level traits (demographic Allee effects). Cooperatively breeding species are an excellent model for investigating the relative importance of Allee effects, because there is a disproportionately larger benefit to an individual of being part of a large group. As a consequence, larger groups have greater performance than small groups, known as the group Allee effect. Although small populations of cooperative breeders may be prone to all levels of Allee effects, empirical evidence for the existence of a demographic Allee effects is scarce. To determine the extent to which Allee effects are present in a cooperatively breeding species, we used a comprehensive 35-year life history database for cooperatively breeding Arabian babblers (Turdoides squamiceps). Firstly, we confirmed the existence of a component Allee effect by showing that breeding individuals in large groups receive greater benefits than those in small groups; second, we confirmed the existence of group Allee effect by showing that larger groups survive longer. And thirdly, we identified a demographic Allee effect by showing that per capita population growth rate is positively affected by population density. Finally, we found that emigration and immigration rates, although dependent on group size, do not buffer against component and group-level Allee effects becoming a demographic Allee effect. Our finding of the existence of all three levels of Allee effects in a cooperative breeder may have important implications for future research and conservation decisions.
 

This morning I awoke to a science media awash with reporting on a new paper produced from a field site that I spent many years at. The work is a new paper, published in Nature, on meerkats and competitive growth. To name (and link) just a few of the news stories, it was covered by the Guardian, Science, Science Daily and National Geographic – pretty widespread and prestigious, not to mention far reaching, media coverage. I don’t want to go into all the ins and outs of this new bit of research, as exciting as it is, as you can just click on the above links or read the article yourself (link and abstract at the end). But the gist is that in meerkat litters, if your siblings are growing faster than you then you increase your food intake and growth rate to try and match them, this was elucidated using some really great experiments (details of that later). This is really important for cooperatively breeding species like meerkats, where reproductive skew is high with only a few individuals ever reaching dominance. So in order to maximise their chances of competing with their litter mates, meerkat pups up their food intake. Simples!
 
What I want to briefly expand on here is the importance of long-term research in this discovery. The study animals used for this work are wild, they all live out their lives in the Kalahari and are beset by the hardships of competition, constant foraging and threats of predation. However, these meerkats (like the babblers that I worked on) are habituated to human observation. This habituation has huge benefits, it allows close observation of interactions, it allows for identifying individuals, it allows for field experiments to be done (be they playing back specific calls or tactically feeding specific meerkats as they did here!) but in the case of the meerkats (and the babblers) it allows researchers to weigh them multiple times a day. You may ask what does this have to do with long-term research? Well meerkats are naturally very skittish, they’re not very big and lots of things want to eat them. It typically takes between 12-24 months to habituate a group up to a good level, from spending hours sitting at a burrow as still as possible but humming the habituation song all the way to walking with them and weighing them. And to have a study population of between 16-25 groups that is a lot of man hours. To get around all of those groups on a regular enough basis you need a small army of researchers, constantly collecting weights, life-history data and helping out with experiments.

This work is also built upon decades worth of other research on these animals, which is not possible without uninterrupted observation. Slowly but surely this work unravelled the natural history of these animals, opening up interesting research questions, which in turn attract researchers with other interest that open up new avenues of research. Long-term studies thus offer a great avenue to expand our knowledge just simply by persisting in one place over a long time. They also tend to build up a network/family tree of researchers who have either worked or done PhDs or post-docs there, and once they move on they are a valuable link between research institutions. Ironically, even though the meerkats have been shown to not be very incestuous, the meerkat research are less averse to such behaviour!
 
All of these ideas are summed up in a great paper entitled: Individuals and populations: the role of long-term, individual-based studies of animals in ecology and evolutionary biology. Long-term study populations exist in many species across all taxa. The meerkats, red deer, Arabian babblers, blue tits, marmots, big horn sheep and pied babblers are just the ones that come off the top of my head. All of these have contributed massively to our understanding of behavioural ecology, population biology and conservation. So when I see a paper like this new meerkat paper I don’t just see the work of the named authors (shout out to Matt Bell – legend) but also to the tens to hundreds of volunteer researchers who have kept those projects going over the decades of their existence (of which I was once one). I hope that after reading this that you’ll appreciate that too.
  
Huchard et al. (2016) Competitive growth in a cooperative mammal. Nature, doi:10.1038/nature17986
 
In many animal societies where hierarchies govern access to reproduction, the social rank of individuals is related to their age and weight1, 2, 3, 4, 5 and slow-growing animals may lose their place in breeding queues to younger ‘challengers’ that grow faster5, 6. The threat of being displaced might be expected to favour the evolution of competitive growth strategies, where individuals increase their own rate of growth in response to increases in the growth of potential rivals. Although growth rates have been shown to vary in relation to changes in the social environment in several vertebrates including fish2, 3, 7 and mammals8, it is not yet known whether individuals increase their growth rates in response to increases in the growth of particular reproductive rivals. Here we show that, in wild Kalahari meerkats (Suricata suricatta), subordinates of both sexes respond to experimentally induced increases in the growth of same-sex rivals by raising their own growth rate and food intake. In addition, when individuals acquire dominant status, they show a secondary period of accelerated growth whose magnitude increases if the difference between their own weight and that of the heaviest subordinate of the same sex in their group is small. Our results show that individuals adjust their growth to the size of their closest competitor and raise the possibility that similar plastic responses to the risk of competition may occur in other social mammals, including domestic animals and primates.

In the spirit of many of my previous blogs I am going to write about a new paper written by someone I know. This may sound like some sort of nepotism, not that many people really read my blog, but this new paper has actually made quite a splash and so I’m really just following a great new science story. If you want to see some of the other coverage then click on these links: Science, Sci News, Science Daily, or PLoS Blogs. (The abstract and link to the paper in question is at the bottom of the blog)
 
This new piece of research is a product of the Hot Birds team at the Fitz in Cape Town, with Tanja van de Ven (lead author) spending many gruelling hours in the Kalahari heat with fairly complex equipment. The team, and Tanja’s, aim is to investigate how birds cope with rising temperatures using species that already exist in the hard thermal conditions of the Kalahari. One of their papers looked at the impact of heat stress on foraging in pied babblers. However, Tanja’s work focuses on yellow-billed hornbills, a species of bird that nests inside trees, with the female sealing herself into this cavity. This reproductive adaptation is great for protecting your eggs and female from predators but it can limit your ability to control your temperature, as you’re pretty stuck (it also means that the female and chicks are 100% dependent on the male for their nutritional needs – such a cool system for male-female and parent-offspring dynamics!!!).
 
The obvious feature of this bird, hopefully you have either clicked on the link or already know what a hornbill looks like from your bird knowledge or from childhood exposure to the Lion King, is that they have a massive long bill. The beak of a bird is not just lifeless tissue like finger nails but very much a living structure and as such has a profusion of blood vessels. Just like the thermoregulation that takes place in humans, where capillaries close to the surface are constricted or relaxed to either conserve or radiate heat, hornbills appear to have the same ability with the blood vessels in their beak. As the ambient air temperature increases more blood is pushed into the hornbill’s beak, allowing heat to be lost through radiative heat transfer. This is similar to toucans, as a recent study has found, but in the toucan this process accounts for upto 60% of non-evaporative heat loss compared to just 8% in the hornbill. There are a number of potential reasons for this: the toucans have much larger bills, hornbills have a harder bill (maybe an ecological adaptation to how they forage?) and toucans start dilating their blood vessels at lower temperatures.
 
This type of research is crucial for understanding how organisms are physiologically adapted to their environment. It enables researchers to better understand the environmental limits that a species may be able to cope with and allow predictions as to the impacts of climate change. It’s also pretty cool too.
 
 
van de Ven et al. (2016) Regulation of heat exchange across the hornbill beak: functional similarities with Toucans? PLoS One
 
Beaks are increasingly recognised as important contributors to avian thermoregulation. Several studies supporting Allen’s rule demonstrate how beak size is under strong selection related to latitude and/or air temperature (Ta). Moreover, active regulation of heat transfer from the beak has recently been demonstrated in a toucan (Ramphastos toco, Ramphastidae), with the large beak acting as an important contributor to heat dissipation. We hypothesised that hornbills (Bucerotidae) likewise use their large beaks for non-evaporative heat dissipation, and used thermal imaging to quantify heat exchange over a range of air temperatures in eighteen desert-living Southern Yellow-billed Hornbills (Tockus leucomelas). We found that hornbills dissipate heat via the beak at air temperatures between 30.7°C and 41.4°C. The difference between beak surface and environmental temperatures abruptly increased when air temperature was within ~10°C below body temperature, indicating active regulation of heat loss. Maximum observed heat loss via the beak was 19.9% of total non-evaporative heat loss across the body surface. Heat loss per unit surface area via the beak more than doubled at Ta > 30.7°C compared to Ta < 30.7°C and at its peak dissipated 25.1 W m-2. Maximum heat flux rate across the beak of toucans under comparable convective conditions was calculated to be as high as 61.4 W m-2. The threshold air temperature at which toucans vasodilated their beak was lower than that of the hornbills, and thus had a larger potential for heat loss at lower air temperatures. Respiratory cooling (panting) thresholds were also lower in toucans compared to hornbills. Both beak vasodilation and panting threshold temperatures are potentially explained by differences in acclimation to environmental conditions and in the efficiency of evaporative cooling under differing environmental conditions. We speculate that non-evaporative heat dissipation may be a particularly important mechanism for animals inhabiting humid regions, such as toucans, and less critical for animals residing in more arid conditions, such as Southern Yellow-billed Hornbills. Alternatively, differences in beak morphology and hardness enforced by different diets may affect the capacity of birds to use the beak for non-evaporative heat loss.

  There are many species that do not just exist with one specific colour pattern. These different colourations are called polymorphisms, existing in a variety of taxa from crabs to lizards to birds. There have been many explanations for the existence of these differences within a species, from protecting against predators to being important for mate choice. There is even a species of lizard, the side-blotched lizard, that exists in three colour morphs that are linked to their behaviour that was famously studied by Barry Sinervo. The orange males are more dominant, the blue males cooperate and the yellow males mimic females. These three morphs live in a state of perpetual flux as none can get the upper hand in the mating game. Basically colour morphs are interesting and we’ve really not touched the surface in understanding the evolutionary mechanisms that lead to and maintain them.

Some really cool studies have been done at the Percy FitzPatrick Institute in Cape Town by Arjun Amar to investigate the two colour morphs of the black sparrowhawk (Accipiter melanoleucus). These majestic birds are either a white or black morph. A new paper has just come out showing that one of the factors that may be keeping these morphs going is the difference in hunting success that they face. Black morphs, unsurprisingly because of their colour, have a higher success in low light levels, while their white breather have the opposite success rates. These success rates tie in with the breeding season of these morphs and may go a long way to explaining the variation in morph distribution across the species South African range. Abstract below:

Tate et al. (2016) Differential foraging success across a light level spectrum explains the maintenance and spatial structure of colour morphs in a polymorphic bird. Ecology Letters
Detectability of different colour morphs under varying light conditions has been proposed as an important driver in the maintenance of colour polymorphism via disruptive selection. To date, no studies have tested whether different morphs have selective advantages under differing light conditions. We tested this hypothesis in the black sparrowhawk, a polymorphic raptor exhibiting a discrete white and dark morph, and found that prey provisioning rates differ between the morphs depending on light condition. Dark morphs delivered more prey in lower light conditions, while white morphs provided more prey in brighter conditions. We found support for the role of breeding season light level in explaining the clinal pattern of variation in morph ratio across the species range throughout South Africa. Our results provide the first empirical evidence supporting the hypothesis that polymorphism in a species, and the spatial structuring of morphs across its distribution, may be driven by differential selective advantage via improved crypsis, under varying light conditions.

These results tie in nicely with previous work that has looked at the ratio of morphs across South Africa. This work found that the Cape peninsula had a very high proportion of black morphs but that this was unlikely to do with a founder effect. More likely it was because of higher rainfall rates during the breeding season, fitting nicely with the recent hunting findings. However, as is often the case in biological systems, hunting and light are not the only potential drivers for polymorphism in this species. It turns out that black morphs have a lower parasite load than white morphs.
 
The great thing about this particular subsection of research on the black sparrowhawk is that it all initially came from the observation that there seemed to be more black morphs in Cape Town than normal. This simple natural history note has spawned a growing number of scientific papers and led to wonderful new insights into evolution. So the next time you notice something when walking about just think that it might be far more interesting than may initially be apparent!

Other black sparrowhawk papers:
 
Amar et al. (2014) Clinal variation in the morph ratio of Black Sparrowhawks Accipiter melanoleucus in South Africa and its correlation with environmental variables. Ibis

Lei et al. (2013) Differential Haemoparasite Intensity between Black Sparrowhawk (Accipiter melanoleucus) Morphs Suggests an Adaptive Function for Polymorphism. PLoS ONE

On Sunday David Attenborough will turn 90. He is possibly the person who has done most to advance the public love for the natural world and in his long career has inspired generations to study the wonderful array of biodiversity we have on this blue-green dot. His tireless, and peerless (sorry but no one else really comes close to him) work has kept nature in the minds of millions and hopefully helped to highlight our impact on the natural world.

His simple blue shirt and chino combo has graced our screen for decades. The melodic tones of his voice and childlike wonder and excitement have relayed the wonders of nature and narrated the epic life stories of untold numbers of species. From plants to insects, mammals to birds, Polar Regions to deserts, and ocean floors to darkest caves, he has helped to illuminate the natural world (IMDb of Big Dave). The most amazing thing is that he seems to be working almost as hard now as he ever has, even abseiling down the new Cambridge Conservation Campus to open it!
Everyone will have differing memories of this towering figure of natural history. Below I tell mine. But here are a few of his “best bits”: LINK

I have been lucky enough to hear the great man speak. He had been at university with the son of Cecily Niven, the woman whose hard work saw the setting up of the Percy FitzPatrick Institute of African Ornithology. They had been good friends and Sir David had agreed many years ago to come and speak at the university. However, over the years of their friendship he had never been able to make it to the Cape to fulfil his promise. He had now made the journey to honour the request made to his now departed university chum. His topic was Birds of Paradise, a subject close to his heart as can be evidenced in his documentary retracing the steps of Wallace to Papua New Guinea. This specious and vibrant group of birds have fascinated naturalist and behaviour biologists for years, with their amazing plumage and courtship displays. His speech was a mesmeric blend of footage, photos and wonderful anecdotes that was topped with a generous sprinkling of natural history. At the end the floor was opened to question, which was a big job as the Baxter Theatre was at full capacity and the crowd were eager to ask questions from a lifetime of viewing the great man on screen. The top question came as a women stood up, unzipped the back of her dress and turned to reveal a full back tattoo of a bird of paradise. She asked ‘what is your favourite species of bird of paradise?’ to which Attenborough replied with a wry smile ‘it would be ungallant of me to say any other then the one on your back.’

I was also fortunate to be able to ask him a question. I had recently seen one of his documentaries where he explained trilobites and the amazing fossils to be found in Morocco. I nervously got up, in front of not just the other PhD students but also most of the Biological Sciences faculty (who had come along even though they weren’t supposed to) and I asked him what his favourite trilobite was. Without really pausing to start his answer and a twinkle in his eye he began to speak, and I was initially saddened. He seemed to either not have heard the question or misunderstood it. My hero, in his dotage was afflicted by senility. However, I couldn’t have been more wrong. With a story telling panache and with witty repartee he spun a long story that went on for almost 10 minutes and culminated in a perfect answer to my question. He was still razor sharp. Afterwards I rushed back to the department with a friend, as we’d heard he was back at the Fitz, and I got a picture with my idol!  

Here is a wonderful Youtube link to 16 of David Attenborough's best moments: LINK

I hope that he can go on for many more year, but I realise that 90 is already a great innings. This man is truly one of the greatest modern Britons, whose work exemplifies what the BBC stands for: public service broadcasting. He has pioneered and championed the best natural history film making and in so doing so done a great service to the natural world, which he is so endlessly fascinated by.

He is my hero.

Last week the Kenyan government burnt a huge stock of Ivory. Here's a link to footage of the multiple tusk bonfires: LINK

This is an impressive act but the question still remains as the the best course of action that governments should take with their siezed Ivory. Ivory is a commodity like anything else: sugar, coffee or chocolate. Supply and demand economics impact on its price. Will destroying a large amount of Ivory drive up price? This could have the knock on effect of increasing poaching as the rewards are greater. Alternatively, such a publicised display may drive down demand and so reduce poaching levels. The poaching networks are complex, crossing continents and with multiple levels and middlemen. Thus, it may be impossible to know the direct impact of Kenya's decision.

There are alternative paths that other Aftican governments have chosen. Under the supervision of CITES, four southern African countries (Botswana, Namibia, South Africa and Zimbabwe) carried out auctions to accredited buyers and raised $15.4 million for conservation. Most of this Ivory was legal Ivory, collected from elephants that had died naturally in national parks. I know private game reserves do the same, and a reserve close to my PhD field site flew about $4 million worth of rhino horn to a safe location. But is this type of sale right? Doesn't it just maintain a market for poached Ivory? Or does it allow governments to generate revenue to protect enigmatic species (and probably loads of others in the process)? (https://cites.org/eng/news/pr/2008/081107_ivory.shtml)

This is the forefront of modern conservation. It's where conservation science, economics (macro and behavioural) and human geography collide. This is one reason for the building of the new Cambridge Conservation Campus, recently opened by Sir David Attenborough. These questions are not easy to solve but they are solvable! http://www.conservation.cam.ac.uk/cambridge-conservation-campus

I'm going to start with some good news, as conservation is typically seen as a doom and gloom area of biology. There are more tigers now than when we last counted! It's the first time for over a century that tiger numbers have increased. This is not only great news for biodiversity but also for lovers of William Blake. Tigers are apex predators, and having a healthy population of the species at the top of the food chain if often crucial for the balance of habitats, for a good example of this see the impact of wolf reintroduction to Yellowstone National Park (or the many scholarly articles). So a healthy and growing tiger population is likely to be beneficial to the environment and other animals. They are also extremely charismatic species, probably up there with the panda and lion. Therefore, these animals have the ability to draw in tourists to come and see them in their native habitat, doing tigery things and everyone loves to see baby animals too. An odd feature of tiger conservation is the impact that the Dalai Lama had on poaching. Tiger skins, and other poached animal parts, were an important part of Tibetan society but the spiritual leader appealed to the people who then burnt their furs and this markedly reduced the market for poached animal products in the region. This highlights the importance of some key figure, almost like key stone species, in changing the behaviours of populations in ways that can benefit the environment. 

However, and there is always a however in conservation, one of the reasons cited for the rise in tiger numbers is moving villages away from tiger habitats. Therein lies the essential problem of a large apex predator living in a very densely populated country: human-wildlife conflict. Solving this problem is what will, in the end, be what leads to the continued survival of this beautiful big cat.

Now to the sad conservation news. Disney's new film Zootropolis has been a smash hit in China. On the surface this might seem great, kids all over the country enjoying watching animals on screen and so maybe taking an interest in them and their behaviour/conservation status. In the trailer that I linked to there is an extended section with a sloth, very strange animals that have to go to the ground to defecate. Unfortunately the outcome seems to have been a bit more sinister, children have fallen in love the one particular character Finnick, who is a fennec fox. This has resulted in families buying fennec foxes for pets. Not only do solitary nocturnal species make awful pets but a rise in the trade of this species, just because of a film is a worrying sign for the trade in exotic species. This species is listed as least concern but it highlights a behavioural consumerism for wildlife that in the long run is unsustainable and if the next fad happens to be an endangered species then it could have huge ramifications for the continuance of a species in the wild.

And completely unrelated to conservation, I read an interesting piece about the 'evolution of evil' on the BBC, worth checking out: ​http://www.bbc.com/earth/story/20160401-how-did-evil-evolve-and-why-did-it-persist

A recent bit of research has just come out that shows that bird populations in Europe and the US are being impacted by our changing climate. This work was even picked up by the BBC. By using a combination of great long-term datasets and some nifty models that they created, the researchers were able to predict current population distributions. This is not just well done research but also a testament to the importance of long-term population monitoring, something that isn’t sexy and since the financial crisis hasn’t received as much funding as other more applied areas of science (sorry this is a pet peeve of mine and I’ll get off this tall equid that I now find myself on). What the research has shown is that species that are predicted to benefit from climate change are benefiting, and those that are predicted to suffer are suffering. Both positive and negative effects can occur within a single species, as they may be declining in southern regions but thriving in northern areas.
 
The trends shown by this new research are large scale continental patterns but what factors may be driving these at a finer, individual level scale? Work done by researchers like Susie Cunningham, Rowman Martin and my pied babbler colleague Lizzie Willey is shedding light on this. Work by these researchers, and others, has shown that when temperature increases it can have dramatic effects on the reproduction of birds, their ability to forage and the viability of their social groups. Nestling fiscal shrikes grow slower when temperatures increase over a threshold level: this increases the risk of nest failure and results in smaller fledglings who are likely to incur a fitness cost. Similarly, on warmer days pied babblers are less efficient at foraging and put on less weight while foraging. If multiple extremely hot days occur in a row this could have a dramatic impact on an individual’s weight, and if they are caring for young then temperature will impact adults, offspring or both. Anecdotal evidence, hopefully soon to be verified statistically, of pied babbler groups is that in the hottest years more groups fail to raise any offspring and become extinct, presumably from the direct effects mentioned above. All of these small individual level mechanisms may help to understand the drivers behind higher level continent wide patters.
 
But climate change doesn’t just act on its own, it occurs in conjunction with direct habitat change caused by humans. Pied crows in South Africa have changed the areas in which they live based on a change in climate but it is facilitated by power lines. These birds need to nest in trees and the existence of power lines has allowed them to colonise treeless areas and take advantage of them.
 
But what does all of this mean? By understanding the lower level effects it may be possible to design or implement habitat measures that can mitigate some of these effects. This may be farfetched, as these are large scale problems. For example when putting up nest boxes for endangered species it is important to ensure that they are not going ‘cook’ the nestlings inside, it’s worth spending that extra time researching this before spending large sums of money on a conservation effort that is doomed to fail. Small and simple considerations like that may have an impact.
 
For more information on this type of research you can visit the Hot Birds Research Project.
 
Some papers that look at the direct effects:

Cunningham et al. (2013) Temperatures in Excess of Critical Thresholds Threaten Nestling Growth and Survival in A Rapidly-Warming Arid Savanna: A Study of Common Fiscals. PLoS ONE
Frequency, duration, and intensity of hot-weather events are all predicted to increase with climate warming. Despite this, mechanisms by which temperature increases affect individual fitness and drive population-level changes are poorly understood. We investigated the link between daily maximum air temperature (tmax) and breeding success of Kalahari common fiscals (Lanius collaris) in terms of the daily effect on nestling body-mass gain, and the cumulative effect on size and age of fledglings. High tmax reduced mass gain of younger, but not older nestlings and average nestling-period tmax did not affect fledgling size. Instead, the frequency with which tmax exceeded critical thresholds (tcrits) significantly reduced fledging body mass (tcrit = 33°C) and tarsus length (tcrit = 37°C), as well as delaying fledging (tcrit = 35°C). Nest failure risk was 4.2% per day therefore delays reduced fledging probability. Smaller size at fledging often correlates with reduced lifetime fitness and might also underlie documented adult body-size reductions in desert birds in relation to climate warming. Temperature thresholds above which organisms incur fitness costs are probably common, as physiological responses to temperature are non-linear. Understanding the shape of the relationship between temperature and fitness has implications for our ability to predict species’ responses to climate change.

Cunningham et al. (2013) Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History. PLoS ONE
Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (Tthresh) above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using Tthresh values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (Tthresh = 35.5°C) and the common fiscal Lanius collaris (Tthresh = 33°C). We used these Tthresh values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > Tthresh), in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance) of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the Tthresh technique as a conservation tool.

Cunninham et al. (2016) Electric crows: powerlines, climate change and the emergence of a native invader. Diversity and Distribution
Aim
Climate change and other anthropogenic global change drivers act in complex, mutually exacerbating ways to alter the abundance and distribution of species. In South Africa, pied crowsCorvus albus have increased in numbers and range in recent decades. Popular opinion links these changes to urbanisation and infrastructure development, but there has been no empirical test of this idea. We aimed to clarify the drivers of pied crow population changes in South Africa.
Location
South Africa.
Methods
We used publicly available long-term datasets, the Southern African Bird Atlas Project and University of Delaware Gridded Climate Database, and spatial data from government bodies, to assess relationships between pied crow population and range changes, land use, infrastructure, urbanisation and climate change.
Results
Pied crow numbers have increased significantly in the past three decades, but rate of increase varied geographically, with crows declining in the northeast and increasing in the south-west of South Africa. Pied crow population changes were strongly correlated with climate change. Crows have benefited most from climate warming in the shrubland biomes of south-western South Africa. Pied crows are tree nesters, and within these shrublands, there is a strong positive relationship between the rate of population increase and the density of powerline infrastructure, which may facilitate pied crows’ increase by providing nesting sites.
Main conclusions
Pied crow numbers have increased in response to climate warming, with their spread facilitated by electrical infrastructure in south-western South Africa, providing a clear example of compound influence of multiple global change drivers promoting a significant change in species range and reporting rate. Pied crows are generalist predators and there is popular concern about their ecological impact in areas where increases have occurred. We highlight the importance of understanding the ecosystem-level implications of increased numbers of pied crows in South Africa's shrubland biomes.

Du Plessis et al. (2012) The costs of keeping cool in a warming world: implications of high temperatures for foraging, thermoregulation and body condition of an arid-zone bird. Global Change Biology
Recent mass mortalities of bats, birds and even humans highlight the substantial threats that rising global temperatures pose for endotherms. Although less dramatic, sublethal fitness costs of high temperatures may be considerable and result in changing population demographics. Endothermic animals exposed to high environmental temperatures can adjust their behaviour (e.g. reducing activity) or physiology (e.g. elevating rates of evaporative water loss) to maintain body temperatures within tolerable limits. The fitness consequences of these adjustments, in terms of the ability to balance water and energy budgets and therefore maintain body condition, are poorly known. We investigated the effects of daily maximum temperature on foraging and thermoregulatory behaviour as well as maintenance of body condition in a wild, habituated population of Southern Pied Babblers Turdoides bicolor. These birds inhabit a hot, arid area of southern Africa where they commonly experience environmental temperatures exceeding optimal body temperatures. Repeated measurements of individual behaviour and body mass were taken across days varying in maximum air temperature. Contrary to expectations, foraging effort was unaffected by daily maximum temperature. Foraging efficiency, however, was lower on hotter days and this was reflected in a drop in body mass on hotter days. When maximum air temperatures exceeded 35.5 °C, individuals no longer gained sufficient weight to counter typical overnight weight loss. This reduction in foraging efficiency is likely driven, in part, by a trade-off with the need to engage in heat-dissipation behaviours. When we controlled for temperature, individuals that actively dissipated heat while continuing to forage experienced a dramatic decrease in their foraging efficiency. This study demonstrates the value of investigations of temperature-dependent behaviour in the context of impacts on body condition, and suggests that increasingly high temperatures will have negative implications for the fitness of these arid-zone birds.

A new paper on how Arabian babblers learn has just come out in Ethology. I've pasted the abstract and link below. This new work shows that dominant individuals are the fastest to learn to shift a learnt skill into a new context, from lifting black rubber lids to lifting white rubber lids, and that learned skills are transmitted horizontally between groups. The study of animal learning and how information is transferred between individuals is a fascinating field of behavioural science. In group living species the ability to learn new information, be it foraging skills or the dominance structure in your group, may be crucial for survival and an individuals prospects of achieving a reproductive position. I know that Oded spent many hours in the field collecting this data and this is a great paper!

Keynan et al. (2016) Task-dependent differences in learning by subordinate and dominant wild Arabian babblers. Ethology, DOI: 10.1111/eth.12488
Learning and innovation abilities have been studied extensively in flocking birds, but their importance and relevance in cooperatively breeding birds have been relatively unexplored. We studied the acquisition of novel foraging skills in 14 groups of wild, cooperatively breeding Arabian babblers (Turdoides squamiceps). While in a previous study we found that subordinate individuals were usually the first to learn to remove black rubber lids from a foraging grid, here we show that dominant individuals were the first to succeed in shifting from these black rubber lids to newly introduced white rubber lids. We also found that in all groups where one forager learned to shift to the white lids, the rest of the foragers also learned to do so, suggesting that this behaviour may be transmitted among group members. Although dominant individuals were almost always the first to remove white lids, once starting to remove white lids, dominants and subordinates learned equally well to prefer white over black lids based on differential reinforcement (food was provided only under white lids). Together with our previous study, our results suggest that differences in learning between dominants and subordinates may be task-specific, which may represent different cognitive strategies: subordinates may explore a more diverse range of foraging opportunities, while dominants may be better at generalizing from familiar tasks to similar ones.

When learning about evolution, every biology student has been taught, since the modern synthesis of natural selection, that mutation of DNA leads to variation that can then be selected on. But how does a random mutation lead to innovation? This process sounds like it might be very slow, even given the ancient age of the earth. How can such small changes create new things? In a great, albeit very dense and intense book, Andreas Wagner (Professor of Evolutionary Biology at the University of Zurich) answers these and many more questions.
 
In “Arrival of the Fittest” Wagner goes to great lengths to take the reader, in a much better way than I can reproduce here, through his ideas about how nature is set up to supercharge evolution. The authors premise is that of a ‘Universal Library’ where every conceivable combination of something can exist. In such a library a single item, be it a DNA code, the sequence of amino acids in a protein or a metabolic pathway, is connected via single changes (in any one of its parts) to other items in the library. Some, in fact probably many of these versions in the library, are useless/defunct in the sense that they would not work in the real world and so any organism that possess them would not survive. However, many of these versions are perfectly viable and so an organism would be able to survive if it had that copy.
 
Using large computer models in these libraries it is possible to move through them by making single changes that do not disrupt the function of the thing you are interested in (be it DNA, protein or metabolism). Following the logic laid down as you go through the book it becomes clear that there are clear pathways through DNA to protein to metabolic pathways. There are even multiple pathways from any one point in the library to any other point (that still gives the same end result) but when the start and end points are compared on their nucleotide/amino acid/enzyme combination level they are completely different. In effect there are many ways to solve the same problem and they are connected in many ways via simple, singular step changes.
 
Not only can the same processes easily be conserved with this logic but new processes are easily made, as these Universal Libraries contain every conceivable combination. Wagner shows that new metabolic pathways can easily be made, allowing for the exploitation of new food stuffs, without loss of function occurring. The amazing thing is that there are huge numbers of these pathways that criss-cross these libraries.
 
These theories show that life processes are robust and that it creates genotype networks which, in Wagner’s words “enable innovation, the very kind that allow life to cope with environmental change, increase its complexity, and so on, in an ascending spiral of ever-increasing innovability.”.
 
I have probably done a very bad job of trying to convey the ideas in this book, but hopefully I have peaked your interest enough to go out an read it, which I definitely recommend (there is a reason that Wagner has been paid to write a book and I haven’t!).
 
This book has genuinely made me look at evolution from a novel perspective, and these revolutionary ideas show how the power of modern computing can be incorporated into evolutionary biology with breath-taking results.