A new pied babbler paper has come out from Martha Nelson-Flower. Martha looked at how long subordinates stayed in their groups and how likely they were to gain a dominant breeding position. In babblers there appears to be a sex difference: males have a longer subordinate tenure when they are related to the dominant male, but there is no impact of relatedness for females (either relatedness to the dominant female or male). But why is this important? Well, it turns out that the longer you are a subordinate for then the more likely you are to attain dominance.

Why would this be the case? Well it may be that dominant males are less tolerant of unrelated males, as they are more likely to compete with them for reproductive opportunities. Related males in pied babbler groups tend to be father and son (with dad being dominant), although it can be the case that one brothers holds the dominant position while the other is subordinate. But why would sticking around as a subordinate be better? Surely it pays to leave quickly and get a dominant position elsewhere, so you yourself can breed. However, gaining dominance is not that easy, vacancies are not that easy to come by and you have to be a pretty big and sexy male to just go and kick another male out of his group. Perhaps it is best just to stay in a group, build up your condition and wait for an opportunity, as going it alone is a very risky business for a babbler!

Nepotism and subordinate tenure in a cooperative breeder. Biology Letters
In many cooperatively breeding societies, subordinate individuals delay dispersal and independent breeding. The length of time that subordinates delay dispersal (subordinate tenure) is likely to have important implications for both subordinate and dominant fitness. However, quantitative comparisons of the subordinate tenure of males and females are rare, especially with respect to the presence of same- versus opposite-sex close kin. Here, we investigate subordinate tenure and how it is affected by the genetic relationship between subordinates and dominants in the cooperatively breeding southern pied babbler (Turdoides bicolor). We find that for males, longer subordinate tenures result in increased likelihood of attaining dominance. In the presence of an unrelated dominant male, tenure of subordinate males is significantly shorter, indicating nepotism among males. Female tenures are unaffected by the genetic relationship to either the dominant male or female. These results are some of the first to demonstrate that the sex of both the dominants and subordinates, and the genetic relationship between them, can have significant impacts on subordinate tenure and dispersal delays. Nepotism has likely played a vital role in the evolution of cooperative breeding in this species.

I’ve just returned from a fun but fairly hectic trip to the Kalahari. This chance came about because there is a new PhD student starting on the pied babblers but no one was available to train her. So, on a plane I hopped and met up with Amanda Bourne. She’s going to be looking at climate effects on the babblers and be part of the Hot Birds Project. Her work is going to be a mix of: physiology, trying to understand the metabolic costs; behavioural, working out if temperature impacts on social and group cohesive behaviours – trying to see if sociality may act as a buffer to high temperatures; and investigating cumulative impacts of high temperature on groups and individuals. All this is really cool, interesting, and (pardon the pun) hot stuff. She is following on from other hot birds work at the Kuruman River Reserve: van de Ven et al. 2016 found that hornbills can regulate blood flow to their beaks to regulate their temperature without evaporative heat loss; du Plessis et al. 2012 found that increasing temperature caused a decrease in the foraging success of pied babblers, with birds displaying heat dissipation behaviour while foraging. She’ll also be able to build on some recent babbler work by Lizzie Wiley who found that adults provisioned nestlings much less on hot days, resulting in decreased nestling growth (Wiley & Ridley 2016).
 
So why was I there? Well the babblers are a bird with lots of complex behaviours, fairly defined territories and the project has specific protocols to maintain consistent data collection over its 13 year history. The privilege fell to me to basically walk around and look at birds for 10 days solid, life is so hard! But in all seriousness, the study population consists of wild birds who have been habituated to close human presence and without knowing how to act around them it is possible to dehabituate them very quickly and see your PhD data quickly fly away. I was also able to help Amanda figure out potential research questions and experiments that she wouldn’t have been able to think of without seeing how they behave.
 
Before heading off I was anticipating a fairly dull period in the field: its winter, they’re hungry and so they just forage and fly about between the distant patches of low density prey. How wrong I was. This has been a very odd year in the Kalahari, late summer rain in April and a mild winter led to a bumper abundance of food. When food is not a problem the babblers, and all of the other Kalahari animals for that matter, get it on and babies are the result. We arrived to find multiple groups with fledglings, and so the veldt was alive with the begging of babblers – music to my ears. Following these groups of babblers where the scimitar bills taking advantage of babbler sentinels and the ubiquitous drongos. We found groups like Centaurus (pictured below) incubating and even observed some egg eating in a group with females who were competing for reproduction. Whilst other groups were having large aerial battles with their neighbours. Amanda was privileged to observe a dispersal event, the dominant female of Vivaldi was fed up with her light weight male and decided to fly across to join the much heavier male of neighbouring group Noleg, even though at one point she flew back to join her old group for a fight against another group before quickly remembering that she’d left.
 
Whilst looking for groups, and teaching Amanda the babbler whistle (an ululating call to get the birds to fly to you) and group territories, we came across wild groups and individuals who had dispersed from the study population (one may have last been seen in the population in 2004!! – although confirmation is still needed). One of these wild groups was right in the middle of the reserve and feeding a nest, so they’ve been named (Martu- pronounced Mardu – after the aboriginal people of the Western Deserts of Australia) and habituation may start in September when Amanda gets back. 

Amanda’s boyfriend, plant biologist and restoration ecologist extraordinaire, Todd Erickson also came along. He was able to use my camera a lot more than I was, and many of the pictures on the blog post were taken by him. Todd’s botanical leanings allowed me to see the veldt in a new way, paying attention to the small succulents, grasses and flowers that had flourished because of the late rains. The Kalahari was filled with colour, majestic in its flora. This colour had been included in the babbler nests, with many of them decorated with the lovely yellow flowers that littered the landscape. Todd’s insights about how dunes actually hold water better than the slacks, meaning that larger trees and shrubs can grow there, blew my mind and made me look at the landscape in a completely new way. This is why I love science, there are so many disciplines and you can always learn something new that changes your world view.
 
I’ve written mostly about the babblers, and that’s because they are awesome, but there are many other projects at the KRR. There is the over 20 year study of meerkats, who have had a terrible year: prior to the late rains it had been a drought and their groups had been decimated by the combined disasters of no recruitment and TB, but they had started to breed in the winter. The Cape Ground Squirrel Project, started by my friend Jamie Samson, is still going strong and again they have had loads of strange winter pups. And for those of you who want to fly to South Africa, travel for hours to the remote Kalahari and then spend most of your time indoors there are always the molerats to work on. That might sound a bit negative but I like being outside and observing animals behaving in their natural habitat and the idea of spending all day under florescent lights (something you can do in an office) in a building that smells of pee (something you get in public toilets) isn’t something that appeals to me. The other cool birds that are studied at the KRR are the hornbills (mentioned above) and the drongos – who spend their time either stealing food from other animals with their vocal mimicry, catching flying insects with ease using their aerial acrobatics or just pissing off large raptors by bomb diving them.

It was very special to go back to the Kalahari, a place that I have spent a lot of time. Seeing the babblers again, watching them play in shepherd’s trees, feed their fledglings or just have them hop on my feet as I weighed them was very special. I also found out that part of my hippocampus is forever engraved with a map of the reserve: I could still walk straight to ladders hidden behind bushes, find trees that had been used as nests in the past and always point to Whiskers Crossing. Part of me will always be in the Kalahari, and no view will ever be as beautiful as the sun setting over the dunes or a time as peaceful as dawn in the veldt.

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.
 

So if you’ve read some of my previous blogs or follow me on Twitter (@alex_babbler), then you’ll probably be aware that some of my PhD research was recently shown as part of the BBC 2 documentary series World’s Sneakiest Animals. So I’m sorry if it feels like over kill to write about this again, but hey it’s not every day that your work appears on TV, let alone a BBC doco! Plus it will probably be the last time, so I’ll milk it for all I can!
 
But this post isn’t really just about my work; it’s about the other cool studies shown on camera. The thing that surprised me the most about the most about this series was the amount of the research that I had either seen presented at conferences or had been done by scientists that I personally know or that I had helped out with. This just goes to show how small a world the behavioural ecology field is, but also how many exciting young scientist there are currently picking apart the natural world (as all of the below research is by young academics). So below I will put a brief description of what is shown on the TV show, a comment on how I knew about it and then a link to the research (as it’s always far more exciting than the 5-10 mins of footage you’ll see on screen).
 
Firstly, the mimetic orchid mantis, whose mimicry is good that they actually attract more pollinators to them than the flowers they are mimicking. This work was done by James O’Hanlon, and I first saw it presented at ISBE in Lund 2012. He’s a great speaker, as shown by this YouTube video: LINK. Because the mantis is larger than and appears brighter than (to the insects they are predating on) than the flowers they are mimicking then they are a supernormal stimulus. It’s just a really cool bit of nature and very elegant research.
 
It appears at 4:09 in Episode 2 (The Hunger Game).
 
http://www.jstor.org/stable/10.1086/673858?seq=1#page_scan_tab_contents
http://www.jstor.org/stable/10.1086/673858?seq=1#page_scan_tab_contents
 
Secondly, drongos stealing food from unsuspecting host species. This bit of storytelling was really a combination of a couple of papers. The first is a paper that I helped with and whose first author is Bruce Baigrie, investigated how drongos use sentinel calls to manipulate sociable weavers in a fascinating mutualism. The second paper and third papers, by Tom Flower, delves into the mimetic alarm calls that drongos use to steal food from their host species. Every time the drongos have appeared on TV it has always been with them shown as stealing food from meerkats, but the species that they hammer the most are the sociable weavers and then possibly the pied babblers. In fact, much of the early work was done looking at the dynamics of how drongos and babblers interacted.
 
It appears at 49:12 in Episode 2 (The Hunger Game).
 
http://rspb.royalsocietypublishing.org/content/281/1791/20141232.short
http://rspb.royalsocietypublishing.org/content/278/1711/1548.short
https://scholar.google.co.uk/citations?view_op=view_citation&hl=en&user=W6TB-BUAAAAJ&citation_for_view=W6TB-BUAAAAJ:ufrVoPGSRksC
 
Thirdly, the show describes how honeyguides parasitise other species to have them raise their own offspring. This is based on the work of Claire Spottiswoode, an amazing field researcher who splits her time between Cambridge, Cape Town and Zambia. Honeyguides lay their eggs in the underground nests of bee-eaters and when their young hatch they hatch early and then grow a sharp hook at the end of their beak that they use to kill their unrelated brood mates - very deadly. By doing this they can monopolise the provisioning of their host offspring. This section of the show also goes into the natural history of cuckoos, and who is a better expert on the subject than Nick Davies. So for the cuckoos I will recommend a great book that goes through not only Prof Davies’ work but that of his forbears and contemporaries.
 
It appears at 43:47 in Episode 3 (Sex, Lies and Dirty Tricks).
 
http://rsbl.royalsocietypublishing.org/content/early/2011/09/06/rsbl.2011.0739.short
http://beheco.oxfordjournals.org/content/18/4/792.short
Cuckoo: Cheating by Nature – Nick Davies
 
Lastly, as it was actually the final part of the series, my work on fledgling provisioning in pied babblers. My work shows that young fledgling babblers, who are amazingly incompetent fliers who are very slow to respond to alarm calls can get fed up to 9 times as much food by moving to areas of danger when predators have been spotted in the local environment. Adults feed the chicks to shut them up and move them to safety.
 
It appears at 51:46 in Episode 3 (Sex, Lies and Dirty Tricks).
 
http://rspb.royalsocietypublishing.org/content/280/1760/20130558.short
 
Other notable studies in the final episode of the series are on Kangeroos (that I think an ex-Cambridg classmate Emily Best) and bowerbirds (which is similar to the work of an ex-colleague Jess Isden), and fiddler crabs that I have blogged about before. It’s a very small world.

I’ve not blogged for a while because the Rugby World Cup has become an all-consuming part of my life. But I thought that I would try and take a break from rugby and write a little bit about some cool science that has come out recently.

Firstly, a new pied babbler paper by Martha Nelson-Flower. This new study has found that, unlike for females, male-male competition is not costly for the dominant male in pied babbler groups. Pied babblers groups are typically highly kin structured, with only the dominant pair being unrelated and so able to breed. But when a subordinate male is unrelated to the dominant female he is able to compete to breed. However, this new study has found that in these situations do arise there is almost no cost to the dominant male: it doesn’t affect the number of successful nests, the number of fledglings fathered by the dominant or his chances of retaining his position. This is in stark contrast to the cost of female competition in this species. When two females are able to breed it delays the onset of breeding, reduces the number of successful breeding attempts and results in females destroying each other’s eggs. Taken together, these two studies show a drastic difference in intrasexual competition in this species that has a huge impact on the group dynamics and evolution of sociality. It also strengthens the arguments put forward about why female fledglings are so much more aggressive than their brothers!

New paper (male-male competition): Male-male competition is not costly to dominant males in a cooperatively breeding bird. Behavioural Ecology and Sociobiology

Old paper (female-female competition): Costly reproductive competition between females in a monogamous cooperatively breeding bird. Proceedings of the Royal Society London B

Secondly, researchers looking at the morphology of Rocky Mountain bees have found that over the last 40 years their tongues have gotten shorter. They suggest that this is due to the changes in flower distribution and abundance brought on by climate change. Because drier weather is reducing the number of flowers, bees have to work harder to find nectar and so bees with traits best suited to the new environment are favoured. It’s amazing to see evolution in action, in a similar way to Claire Spottiswoode’s work on honey guides.

Bee paper: Functional mismatch in a bumble bee pollination mutualism under climate change. Science

The study’s lead author Nicole Miller-Struttmann suggest the reason for the direction of evolution are that “It would take longer to find the deep flowers, so the longer-tongued bees are going to spend more time searching. But if you’re a generalist, short-tongued bee, you’re more likely to run into your resource.”

The BBC have just finished filming some of the work that I did for my PhD (while I was at the Percy FitzPatrick Institute). The filming involved Chris Packham doing one of my experiments, which is pretty awesome.

They filmed work from my Proc Roy Soc paper
Thompson et al. (2013) The influence of fledgling location on adult provisioning: a test of the blackmail hypothesis

While at the KRR they also filmed the drongo -sociable weaver interaction from work that I helped Tom Flower and Bruce Baigrie carry out, also published in Proc Roy Soc
Baigrie et al. (2014) Interspecific signalling between mutualists: food-thieving drongos use a cooperative sentinel call to manipulate foraging partners

So all in all, a great bit of coverge for research carried out and funded by the Fitz!

The above picture is of the BBC film crew that came out and the members of Babbler Project who helped them with the filming.

This is a very brief post to draw people's attention to some things that other people have done. One is an article that a former field assistant at the Babbler Project has written and the other is from PhD comics.

Firstly, Robbie Hopper, who was a PhD field assistant for James Westrip, has written an article about the Babbler Project and the research that has been done on those amazing birds (I am very biased as I spent four years working on them). So here is the link: http://ecopostblog.wordpress.com/2014/06/22/dabblings-with-babblers/

Secondly, PhD comics, the website that probably millions of graduate students look up on a regular basis to provide accurate commentary on their lives, has done a cool cartoon short about Miya Warrington's PhD thesis. This is awesome for two reasons: firstly, her thesis was really interesting and the science is sound; secondly, I sat next to Miya for two months when I visited Macqaurie University while I was writing up my PhD. She's a very enthusiastic and dedicated scientist and it's great to see her work publicised in this way! So here is the link:
http://phdcomics.com/comics/archive.php?comicid=1726

I know this ‘coverage’ is a bit late but I was on a remote Scottish Island when this paper came out and as Tom is the first of my friends to get a paper in Science I obviously had to write about it. And as you will now know, I know the authors and so my slant on this paper will probably be biased in a positive way.

So the paper is:

Flower et al (2014) Deception by flexible alarm mimicry in an African Bird. 344: 513-516

Firstly you’ll need a bit of background on fork-tailed drongos (Dicrurus adsimilis), hereafter drongos. They are extremely agile birds that live in Southern Africa and are very adept at hawking small flying insects. In addition to their aerobatics they are vocal mimics that can copy the calls of other species, and they use these calls to make false alarm calls (i.e. when there are no real predators) to scare individuals from other species (host species) when they have food, then they fly down and steal the food item. Drongos primarily spend time with sociable weavers (Philetairus socius), pied babblers (Turdoides bicolor) and meerkats (Suricata suricatta). Previous work has investigated some of these associations, and I have put the papers at the end.

The problem with using these false alarm calls to gain food from other species, usually food that drongos are unable to gain themselves, is that if you are deceptive too often then your hosts will stop responding. However, these host species don’t just have their food stolen by drongos, they actually use drongos as part of their vigilance system as drongos will alarm at actual predators. Thus there is an interesting ‘mutualism’ that exists within this system. This investigation sought to understand how drongos maximize their gain from these repeated interactions.

Natural observations of this wild population showed that drongos exclusively use mimetic alarm calls in 42% of false alarms and a combination of mimetic and drongo specific calls in a further 27%. To investigate these patterns the researchers carried out a playback experiment using four drongo generated call types:  1) a control territorial call 2) drongo-specific alarm 3) mimic of glossy starling (Lamprotornis nitens) alarm and 4) mimic of pied babbler alarm. The experiment was carried out on groups of habituated pied babblers, a host species for the drongos. Pied babblers were slower to return to foraging after mimetic alarms than drongo specific ones, thus showing that mimetic alarm calls produce a stronger response. They then carried out a second experiment where they played back three calls in one of four treatments: 1) All drongo-specific alarms 2) All mimetic starling alarms 3) two drongo followed by a starling and 4) two starling followed by a drongo alarm. They found that pied babblers habituated to treatments of all one type but not to the treatments that varied. Showing that varying the calls you use has benefits for the drongo. These experimental results fit with the natural data that showed in instances of repeated attempts at theft on the same individual that drongos changed the false alarm call that they used on 74% of occasions. Drongos were more likely to change if their previous attempt had failed.

This paper shows that drongos avoid host species habituating to false alarm calls by varying the mimetic false alarms that they use and thus avoiding frequency dependent constraints.

This paper has a great blend of natural observation and carefully designed experiments. The results speak for themselves and tell an interesting story of how birds in the wild adjust to problems that are familiar to many people. It shows the value of working at a research site with multiple habituated species that associate and interact in interesting ways, and thus the value of long-term research stations.

Some of the media coverage seems to have sensationalized this work, going much further with their assertions than the authors did. Some have even suggested that these birds have ‘theory of mind’. Sciencemag noted that Tom (Dr Flower) is doing some current work to further investigate drongos tactics and learning, work that I assisted with in the Kalahari. From my observations while performing these experiments the drongos seemed to use simple rules and were not as clever as we had hoped. However, that does not detract from the brilliance of their behaviour: many complex behaviours and structures are made using simple rules, e.g. spider’s webs and wasp nests. Even some seemingly complex human behaviours are governed by simple rules. The amazing adaptability of evolution is shown by such seemingly complex behaviours. In fact the authors use examples such as the changing of cell surface proteins by influenza as an analogue to drongo behaviour, and I’m pretty sure that virus’s don’t have theory of mind!

Here are some links to other media coverage:

http://news.sciencemag.org/biology/2014/05/african-bird-cries-wolf-steal-food?rss=1

http://whyfiles.org/2014/deceptive-bird-lies-to-steal-food/

http://www.nbcnews.com/science/weird-science/african-bird-uses-sound-effects-bamboozle-other-species-n94256

More drongo papers:

Flower et al (2013) The ecological economics of kleptoparasitism: pay-offs from self-foraging versus kleptoparasitism. Journal of Animal Ecology 82:245-255

Flower & Gribble (2012) Kleptoparasitism by attacks versus alarm calls in fork-tailed drongos. Animal Behaviour 83:403-410

Ridley & Child (2009) Specific targeting of host individuals by a kleptoparasitic bird. Behavioral Ecology & Sociobiology 63: 1119-1126.