Sociable Weaver Research Project
Dr Rita Covas
Dr Claire Doutrelant (CEFE-CNRS, France)
Members of the research project
Dr Sophie Lardy (Postdoctoral fellow, FitzPatrick Institute)
Dr Arnaud Tognetti (Postdoctoral fellow, IAST, France)
André Ferreira (PhD student, CIBIO, University of Porto, Portugal)
Liliana Silva (MSc student, CIBIO, University of Porto, Portugal)
Rita Fortuna (MSc student, CIBIO, University of Porto, Portugal)
Dr Matthieu Paquet (University of Edinburgh, UK)
Dr Claire Spottiswoode (FitzPatrick Institute)
Prof. Ben Hatchwell (Sheffield University, UK)
Dr René van Dijk (Sheffield University, UK)
Dr Res Altwegg (Dept Statistical Sciences, UCT)
Dr Fanny Rybak (University Paris Sud, France)
Dr Bruno Faivre (University of Dijon, France)
Project overview and current directions
The sociable weaver Philetairus socius is a small southern African bird, which is remarkable for its elaborate social organisation and cooperative behaviour – from building communally one of the most remarkable structures in the bird world, to cooperatively raising young or mobbing predators. The sociable weaver research program uses an individually marked population of sociable weavers to study the evolutionary bases of cooperative behaviour and the rules that allow cooperation to persist. This is one of the longest running bird studies in Africa and our long-term data is used also to address fundamental questions about the factors driving population dynamics and predict responses to environmental change.
Current work is focusing on 1) direct fitness benefits arising from cooperation and in particular via social/sexual selection; 2) physiological costs of helping; 3) Maternal effects and manipulation of parental care (in collaboration with Matthieu Paquet, University of Edinburgh); 4) kin recognition and inbreeding avoidance (in collaboration with Ben Hatchwell and René van Dijk; 5) Factors affecting population dynamics (in collaboration with Res Altwegg, UCT).
Sociable Weaver Research Programme – Beginnings
The Sociable Weaver study was initiated in 1993 by Mark Anderson (currently executive director of Birdlife South Africa). Then an ornithologist at Northern Cape Nature Conservation and based in Kimberley, Mark was interested in getting people involved in bird ringing while collecting basic demographic data. In 1998, Rita Covas initiated a PhD project on the cooperative breeding behaviour and life history strategies of the sociable weavers through the Percy FitzPatrick Institute at the University of Cape Town. Claire Doutrelant joined the study soon after with a post-doc project and this collaboration has continued to this day. Although the study of cooperation was interrupted after Rita’s graduation in 2002, the population monitoring continued through Claire Spottiswoode’s PhD project on phenotypic and life-history differentiation among colonies. In 2008 Rita Covas and Claire Doutrelant went back to Benfontein to relaunch the research program and the project has been growing since.
Cooperative nest building
The massive nests of sociable weavers are believed to be built communally by all colony members, but how is this cooperation maintained? Who builds where and when and, more interestingly, how is cheating avoid? The weavers’ communal nest structure is a ‘common good’ that requires constant work to repair and enlarge. It therefore provides an ideal setting to investigate how the ‘tragedy of the commons’ can be avoided. The tragedy of the commons arises when common goods cannot be maintained because individuals acting selfishly do not contribute to the maintenance of the common good, even though in the long run everyone benefits from having it. Post-doctoral Fellow René van Dijk and Professor Ben Hatchwell from Sheffield University started working on the sociable weavers at Benfontein in 2010 with the specific objective of investigating this conundrum.
More about the team
Dr Rita Covas (CIBIO, University of Porto, Portugal and Percy FitzPatrick Institute)
I have a broad interest in the evolution of life history strategies and sociality in birds. My research activity focuses on two main topics: 1) the evolution of sociality and cooperative behaviour; 2) Life-history and behavioural adaptations on islands. I have used birds, and in particular the sociable weaver, to address these questions through individual-level and comparative studies. My previous research on sociable weavers has focused mostly on the costs and benefits of cooperative breeding and the genetic structure of these weavers’ society. This focus has now shifted to take a broader approach to cooperation and social behaviours in this species - both during and outside the breeding season. One of my main current interests is understanding the relative role of direct vs. indirect (kin-selected) benefits in maintaining cooperation. In addition, I am fascinated by these weavers’ flexible reproductive strategies and how reproductive investment, social factors and the unpredictable Kalahari climate determine population dynamics in this species.
My other life as a researcher investigates behavioural and life-history adaptations to insularity. Islands are simplified environments with similar characteristics, providing replicates of natural experiments in evolution that allow us a better understanding of evolutionary mechanisms. I have been investigating patterns of adaptation on islands worldwide concerning reproductive life-histories, sociality and sexual ornaments. In addition, my collaborators and I conduct a field study in São Tomé and Principe islands and nearby mainland to investigate the mechanisms underlying these adaptations.
Claire Doutrelant (CEFE-CNRS, France)
In addition to these questions, I also work on the evolution of signals (colour and acoustic signals). For this I use long term data from both sociable weaver and blue tit coloration. More recently, I also became interested in the use of comparative approaches. Besides being interested in the functions of the signals presented by both sociable weavers and blue tits and the effect of environment on the spatio-temporal variation of the coloration, I’m interested on the evolution of female ornament and on evolution of behaviours and communication on islands.
Sophie Lardy (Postdoctoral Fellow, FitzPatrick Institute)
My post-doc is focusing on the physiological cost of helping in the sociable weaver. Cooperation can only arise if benefits are greater than the costs, and across cooperative species there has been great effort to quantify the benefits, but little attention has been given to the costs. I am using both correlational and experimental approaches to investigate the costs underlying cooperative investment in nestling feeding in terms of oxidative stress, telomere length and survival.
Arnaud Tognetti (Institute for Advanced Study in Toulouse, IAST)
My research projects focus on the evolution of cooperative behaviour and more specifically whether cooperation can be sexually selected. Cooperation in animals has been largely explained by kin selection theory. However, the importance of direct benefits, especially the social and reproductive ones, has been overlooked. During my PhD I mainly used humans as a model species. My findings show that men are more cooperative in the presence of potential sexual partners, that women sexually prefer cooperative men and that some physical traits seem to signal men’s cooperativeness. Despite a growing evidence supporting the hypothesis that human cooperation is sexually selected, virtually no empirical studies in non-human species have been conducted. My current projects attempt to fill in this gap using the mound-building mouse (Mus spicilegus) and the sociable weaver. In the mound-building mouse, preliminary results show that females prefer males that are more cooperative in building the mound. In the sociable weaver, I am testing whether cooperation can be a signal. Notably, I am investigating whether helpers change their feeding behaviour when potential mates are around. I am conducting play-back experiments to simulate different audiences in order to test whether the helper’s behaviour change according to the sex and the identity of individuals in the audience. Finally, I am also examining the genetic underpinnings of cooperative behaviour by a candidate-gene approach. More specifically, I am testing a potential association between helping behaviour and the polymorphism of the dopamine D4 receptor (DRD4) gene.
André Ferreira (CIBIO-InBio, University of Porto)
During my MSc I investigated if the sociable weaver breeders gradually transfer part of the parental care to their helpers and if this represents a cost for the nestlings. For my PhD I will focus on the role of social and sexual selection on the evolution and maintenance of cooperation. My aim is to understand if cooperative behaviour will increase the probability of mating in the future and investigate social benefits using social network analysis. I will the consistency and reliability of cooperative behaviour by investigate whether individuals invest consistently in different cooperative tasks (nest defence, nest building and feeding the chicks) and I will run personality trials (boldness, exploration and sociability) both in the wild and in captivity to test if the aptitude to cooperate is part of a behavioural syndrome.
Rita Fortuna (CIBIO-InBio, University of Porto)
My master project aims to further assess whether sociable weaver females can use maternal effects to indirectly manipulate other individuals to provide offspring care. I’ve monitored the breeding season of several sociable weaver colonies in Kimberley, South Africa, and I’m performing video and acoustic analyses to extract correlations on the provisioning behaviour of the adult birds in relation to the offspring begging that is directed to them. I aim to understand the dissimilarities in the amount of care provided by birds with different status, paying close attention to the differences between male and female breeders and among the non-breeding cooperative individuals.
My MSc thesis focuses on the physiological costs entailed in acquisition and maintenance of dominance. I am currently investigating if there are hidden physiological challenges and higher energy expenditure associated with the frequent engagement in aggressive behaviours and dominance status maintenance. These physiological challenges may involve maintaining higher levels of stress hormones and testosterone, both related with the production of reactive oxygen species and, ultimately, with oxidative stress. I also intend to relate such costs with status signalling through plumage colour signals termed as “badge of status”.
Matthieu Paquet (IEB, University of Edinburgh, Scotland)
I am broadly interested in behavioural ecology and more specifically in family interactions and the potential role of maternal effects as a mediator of family conflicts.
During my PhD and Post Doc with Rita Covas and Claire Doutrelant we investigated maternal effects induced by the presence of helpers and their consequences on females, males and offspring behaviour and fitness in Sociable Weavers. Among other results, we found that females laid smaller eggs containing less testosterone and corticosterone when they expected to be helped. Additionally, females’ survival increases while males’ survival decreases with the number of helpers. Finally, a cross fostering experiment revealed that chicks originating from groups with more helpers begged less than chicks from pairs without helpers early after. These results suggests that females could modulate offspring begging behaviour through maternal effects depending on breeding conditions (in this case, the presence of helpers).
I am now working on a 2 years post-doc project (Fyssen grant) in Edinburgh with Per Smiseth aiming to test the possibility that females may manipulate male parental investment through maternal effects, using the burying beetle Nicrophorus vespilloides as a model species. I co-supervise with Claire and Rita an MSc student (Rita Fortuna) who is investigating whether females modulate offspring begging behaviour in relation to the number of helpers through maternal effects.
Previous Students (last 3 years)
Kyle Lloyd: An experimental approach to assess the role of nest predation in the population dynamics of the sociable weaver (Philetairus socius) MSc, PFIAO, UCT (2016)
Margaux Rat: Dominance, social organisation and cooperation in the sociable weaver (Philetairus socius). PhD, University of Cape Town (2015)
Sofia Santos: Effects of group size on maternal allocation in a colonial cooperative breeding bird, the sociable weaver. MSc, University of Lisbon (2015)
André Ferreira: Benefits and costs of helpers: investigating the underlying mechanisms (July 2015, University of Porto). MSc, University of Porto (2015)
Matthieu Paquet: Maternal effects and life history trade-offs in a cooperative breeder, the sociable weaver (Philetairus socius). PhD, University of Montpellier (2013)
Lara Broom: The effect of helpers on the post-fledging period of a cooperatively breeding bird, the sociable weaver. MSc, University of Porto (2013)
The DST/NRF Centre of Excellence at the Percy FitzPatrick Institute
Portuguese Science and Technology Foundation (FCT)
French Research Agency (ANR)
Marie Curie - IRSES
Natural Environment Research Council (NERC)
Sociable Weaver project publications
Paquet. M., Doutrelant, C., Loubon, M., Theron, F., Rat, M. and Covas, R. 2016. Communal roosting, thermoregulatory benefits and breeding group size predictability in cooperatively breeding sociable weavers. Journal of Avian Biology 47(6): 749-755.
Acker, P., Gregoire, A., Rat, M., Spottiswoode, C.N., van Dijk, R.E., Paquet, M., Kaden, J., Pradel, R., Hatchwell, B.J., Covas, R. and Doutrelant, C. 2015. Disruptive viability selection on a black plumage trait associated with dominance. Journal of Evolutionary Biology 28: 2027–2041.
Paquet, M., Doutrelant, C., Hatchwell, B.J., Spottiswoode, C.N. and Covas, R. 2015. Antagonistic effect of helpers on breeding male and female survival a cooperatively breeding bird. Journal of Animal Ecology 84: 1354–1362.
van Dijk, R.E., Covas. R/, Doutrelant. C., Spottiswoode, C.N. and Hatchwell, B.J. 2015. Fine-scale genetic structure reflects sex-specific dispersal strategies in a population of sociable weavers (Philetairus socius) Molecular Ecology 24: 4296–4311.
Paquet, M., Covas, R. and Doutrelant, C. 2015. A cross-fostering experiment reveals that prenatal environment affects begging behaviour in a cooperative breeder. Animal Behaviour 102: 251-258.
Rat, M., van Dijk, R.E., Covas, R., and Doutrelant, C. 2015. Dominance hierarchies and associated signalling in a cooperative passerine. Behavioral Ecology and Sociobiology 69: 437-448.
Altwegg, R., Doutrelant, C., Anderson, M.D., Spottiswoode, C.N. and Covas, R. 2014. Climate, social factors and research disturbance influence population dynamics in a declining sociable weaver metapopulation. Oecologia 174: 413–425
Paquet, M., Covas, R., Chastel, O., Parenteau, C. and Doutrelant, C. 2013. Maternal effects in relation to helper presence in the cooperatively breeding sociable weaver. PlosOne, 8, e59336.
van Dijk, R.E., Kaden, J.C., Argüelles-Ticó, A., Beltran, L.M., Paquet, M., Covas, R., Doutrelant, C. and Hatchwell, B.J. 2013. The thermoregulatory benefits of the communal nest of sociable weavers Philetairus socius are spatially structured within nests. Journal of Avian Biology, 44: 102–110.
Covas, R. 2012. Evolution of reproductive life histories in island birds worldwide. Proceedings of the Royal Society of London B, 279, 1531-1537. doi:10.1098/rspb.2011.1785.
Cornuau, J. H., Rat, M., Schmeller, D. S. and Loyau, A. 2012. Multiple signals in the palmate newt: ornaments help when courting. Behavioral Ecology and Sociobiology, 66(7), 1045-1055.
Doutrelant, C., Dalecky, A. and Covas, R. 2011. Age and relatedness have an interactive effect on the feeding behaviour of helpers in cooperatively breeding sociable weavers. Behaviour, 148, 1399-1417.
Covas, R., Deville, A.-S., Doutrelant, C., Spottiswoode, C.N. and Gregoire, A. 2011. The effect of helpers on the postﬂedging period in a cooperatively breeding bird, the sociable weaver. Animal Behavior, 81, 121-126.
Spottiswoode, C.N. 2009. Fine-scale life-history variation in sociable weavers in relation to colony size. Journal of Animal Ecology 78, 504-512.
Covas, R., du Plessis, M. and Doutrelant C. 2008. Helpers in a colonial cooperatively breeding bird help to counteract the effects of adverse breeding conditions. Behavioral Ecology and Sociobiology, 63, 103-112.
Gimenez O., Viallefont A., Charmantier A., Pradel R., Cam E., Brown C.R., Anderson M.D., Brown M.B., Covas R. and Gaillard J.-M. 2008. The risk of flawed inference in evolutionary studies when detectability is less than one. American Naturalist 172, 441–448.
Schwager, M., Covas, R., Blaum, N. and Jeltsch, F. 2008. Limitations of population models in predicting climate change effects: a simulation study of sociable weavers in southern Africa. Oikos 117:1417-1427.
Doutrelant, C. and Covas, R. 2007. Helping has signalling characteristics in a cooperatively breeding bird. Animal Behaviour. 74, 739-747.
Spottiswoode, C.N. 2007. Phenotypic sorting in morphology and reproductive investment among Sociable Weaver colonies. Oecologia 154, 589-600.
Covas, R., Dalecky, A., Caizergues, A. and Doutrelant, C. 2006. Kin associations and direct vs. indirect genetic benefits in sociable weavers Philetairus socius. Behavioral Ecology and Sociobiology, 60, 323-331.
Gimenez, O., Covas, R., Brown, C.R., Anderson, M.D., Brown, M.B. and Lenormand, T. 2006. Nonparametric estimation of natural selection on a quantitative trait using mark-recapture data. Evolution, 60, 460-466.
Covas, R. and du Plessis, M.A. 2005. The effect of helpers on artificially increased brood size in sociable weavers (Philetairus socius). Behavioral Ecology and Sociobiology, 57, 631-637.
Covas, R., Doutrelant, C. and du Plessis, M.A. 2004. Experimental evidence of a link between breeding conditions and the decision to breed or to help in a colonial cooperative bird. Proceedings of the Royal Society of London B., 271, 827-832.
Covas, R., Brown, C.R., Anderson, M.D. and Brown, M.B. 2004. Juvenile and adult survival in the sociable weaver (Philetairus socius), a southern-temperate colonial cooperative breeder in Africa. Auk, 121, 1199-1207.
Doutrelant, C., Covas, R., Caizergues, A. and du Plessis, M.A.. 2004. Unexpected sex ratio adjustment in a colonial cooperative bird: pairs with helpers produce more of the helping sex whereas pairs without helpers do not. Behavioral Ecology and Sociobiology, 56, 149-154.
Covas, R., Doutrelant, C. and Huyser, O. 2004. Nest-dependant Pigmy Falcons predate on their host, the sociable weaver. Ostrich, 75, 325-326.
Brown, C.R., Covas, R., Anderson, M.D., Bomberger Brown, M. 2003. Multistate estimates of survival and movement in the sociable weaver. Behavioral Ecology, 14, 463-471.
Covas, R., Brown, C.R., Anderson, M.D. and Bomberger Brown, M. 2002. Stabilising selection on body mass in the sociable weaver. Proceedings of the Royal Society of London B, 269, 1905-1909.