PhD (Cape Town)

The central themes of Rita's research are the causes and consequences of sociality and life histories in birds. Rita uses a combination of field-based and comparative approaches. Her main study system is a long-term study on Sociable Weavers, a colonial cooperative bird with a complex social structure, based at Benfontein Nature Reserve. This has been conducted in collaboration with several people, in particular Claire Doutrelant (CEFE-CNRS, France). Since 2017 Rita has coordinated the Fitz-based long-term study on Southern Ground-Hornbills, another group-living, cooperative species that is currently listed as ‘Endangered’ in South Africa. This study is based at the Associated Private Nature Reserves near Hoedspruit.

Rita's other major research interest is evolution on islands. Island systems are wonderful ‘natural laboratories’ and Rita has been conducting comparative and field-based research to unravel patterns of adaptation in island birds worldwide as well as the mechanisms underlying these changes. Previous studies focused, for example, in patterns of parallel evolution in reproductive life-histories and plumage colouration. The field component of this work is conducted mostly in the Gulf of Guinea islands and adjacent mainland in Gabon and Cameroon, West Africa. Here, Rita has investigated blood parasites, immunity and secondary sexual traits (colour and song). This research is being done in collaboration with Claire Doutrelant, Martim Melo (CIBIO, University of Porto), and Claire Loiseau (CIBIO, University of Porto).

About Rita:

Rita is a Principal Researcher at CIBIO (University of Porto, Portugal) and an Honorary Research Associate at the Fitz. She completed her undergraduate studies at the University of Lisbon, which included a graduation dissertation on the biogeography of Mediterranean birds conducted at the CNRS in Montpellier, France, with Jacques Blondel. After graduating, she obtained a BP Conservation Award, to work on the poorly known seabird community of São Tome and Principe in the Gulf of Guinea, West Africa together with Luis Monteiro (University of the Azores) and Martim Melo (now at CIBIO, University of Porto).

In 1998 Rita moved to Cape Town to start a PhD at the Percy FitzPatrick Institute studying cooperative breeding behaviour in the Sociable Weaver under the supervision of Morné du Plessis. After her PhD, she moved to the University of Edinburgh and started to work on the birds from the Gulf of Guinea islands. Later she obtained a Marie Curie fellowship to expand this work at the CEFE-CNRS in Montpellier, France. At the end of 2008 Rita returned to South Africa to re-launch the sociable weaver study and became a Research Associate at the Fitz. In 2010 she obtained a position as a researcher at CIBIO (University to Porto, Portugal), where she currently works as a Principal Researcher. She has been an Honorary Research Associate of Fitz since 2015.

Current students (UCT)

Carrie Hickman (MSc): Climate change impacts on breeding success in Southern Ground Hornbills. (Co-supervisor: Susie Cunningham)

Recent peer-reviewed publications

Melo, M., Covas, R., Lima, R.F., Veiga da Horta, O., do Bom Jesus, C., Barros da Veiga, M., Samba, S., Fonseca, R., Cabinda, G., Viegas, L., Silva, T.L., Mata, V.A., Beja, P., Ferreira, S. 2023. DNA Barcode library of the endemic-rich avifauna of the oceanic islands of the Gulf of Guinea. Biodiversity Data Journal 11.  https://doi.org/10.3897/BDJ.11.e110428

Fortuna, R., Paquet, M., Biard, C., Élard, L., Ferreira, A.C., Leroux-Coyaux, M., Parenteau, C., Silva, L.R., Théron, F., Covas, R. and Doutrelant, C. 2023. Egg components and offspring survival vary with group size and laying order in a cooperative breeder. Oecologia 202: 129-142. https://doi.org/10.1007/s00442-023-05379-w

Halupka, L., Arlt, D., Tolvanen, J., Millon, A., Bize, P., Adamík, P., Albert, P., Arendt, W.J., Artemyev, A.V., Baglione, V., Bańbura, J., … and Covas, R. 2023. The effect of climate change on avian offspring production: A global meta-analysis. Proceedings of the National Academy of Sciences 120(19). https://doi.org/10.1073/pnas.2208389120

Ponti, R., Doutrelant, C. and Covas, R. 2023. Strength of the ‘island rule’ in birds is positively associated with absence of avian predators. Biology Letters 19(3). https://doi.org/10.1098/rsbl.2022.0536

Covas, R., Lardy, S., Silva, L.R., Rey, B., Ferreira, A.C., Theron, F., Tognetti, A., Faivre, B. and Doutrelant, C. 2022. The oxidative cost of helping and its minimization in a cooperative breeder. Behavioral Ecology. https://doi.org/10.1093/beheco/arab152

D’Amelio, P.B., Ferreira, A.C., Fortuna, R., Paquet, M., Silva, L.R., Theron, F., Doutrelant, C. and Covas, R. 2021. Disentangling climatic and nest predator impact on reproductive output reveals adverse high‐temperature effects regardless of helper number in an arid‐region cooperative bird. Ecology Letters 25: 151–162. https://doi.org/10.1111/ele.13913 IF: 9.492

Fortuna, R., Paquet, M., Ferreira, A.C., Silva, L.R., Theron, F., Doutrelant, C. and Covas, R. 2021. Maternal allocation in relation to weather, predation and social factors in a colonial cooperative bird. Journal of Animal Ecology 90: 1122–1133. https://doi.org/10.1111/1365-2656.13438 

Quque, M., Paquet, M., Zahn, S., Théron, F., Faivre, B., Sueur, C., Criscuolo, F., Doutrelant, C. and Covas, R. 2021. Contrasting associations between nestling telomere length and pre and postnatal helpers’ presence in a cooperatively breeding bird. Oecologia 196: 37-51. https://doi.org/10.1007/s00442-021-04917-8 

Reis, S., Melo, M., Covas, R., Doutrelant, C., Pereira, H., de Lima, R. and Loiseau, C. 2021. Influence of land use and host species on parasite richness, prevalence and co-infection patterns. International Journal for Parasitology 51(1): 83-94. https://doi.org/10.1016/j.ijpara.2020.08.005 

Bliard, L., Paquet, M., Robert, A., Dufour, P., Renoult, J.P., Grégoire, A., Crochet, P.A., Covas, R. and Doutrelant, C. 2020. Examining the link between relaxed predation and bird coloration on islands. Biology Letters 16(4). https://doi.org/10.1098/rsbl.2020.0002 

Ferreira, A.C., Covas, R., Silva, L.R., Esteves, S.C., Duarte, I., Fortuna, R., Theron, F., Doutrelant, C. and Farine, D.R. 2020. How to make methodological decisions when inferring social networks. Ecology and Evolution. https://doi.org/10.1002/ece3.6568 

Ferreira, A.C., Silva, L.R., Renna, F., Brandl, H.B., Renoult, J.P., Farine, D.R., Covas, R. and Doutrelant, C. 2020. Deep learning-based methods for individual recognition in small birds. Methods in Ecology and Evolution 11: 1072-1085 https://doi.org/10.1111/2041-210X.13436 

Covas, R., and Doutrelant, C. 2019. Testing the Sexual and Social Benefits of Cooperation in Animals. Trends in Ecology & Evolution, 34(2), 112–120. http://dx.doi:10.1016/j.tree.2018.11.006.

Jansen, D.Y., Pradel, R., Mares, R., Doutrelant, C., Spottiswoode, C.N., Covas, R. and Altwegg, R. 2019. An integrated population model sheds light on the complex population dynamics of a unique colonial breeder. Population Ecology. https://doi.org/10.1002/1438-390X.12010 

Robert, A., Lengagne, T., Melo, M., Gardette, V., Julien, S., Covas, R., Gomez, D. and Doutrelant, C. 2019. The theory of island biogeography and soundscapes: Species diversity and the organization of acoustic communities. Journal of Biogeography 46(9): 1901-1911. https://doi.org/10.1111/jbi.13611 

Silva, L. R., Lardy, S., Ferreira, A. C., Rey, B., Doutrelant, C. and Covas, R. 2018. Females pay the oxidative cost of dominance in a highly social bird. Animal Behaviour, 144, 135–146. doi:10.1016/j.anbehav.2018.08.006.

Paquet, M. and Covas, R. IP. Communal Behaviour. Encyclopedia of Animal Cognition and Behavior. J. Vonk, T.K. Shackelford (eds.) Springer.

Lloyd, K.J., Altwegg, R., Doutrelant, C. and Covas, R. 2017. Factors affecting the foraging distance and duration of a colonial bird, the sociable weaver, in a semi-arid environment. African Journal of Ecology 56: 659-663. http://dx.doi.org/10.1111/aje.12484 

Lobato, E., Doutrelant, C., Melo, M., Reis, S. and Covas, R. 2017. Insularity effects on bird immune parameters: a comparison between island and mainland populations in West Africa. Ecology and Evolution 7: 3645-3656. http://dx.doi.org/10.1002/ece3.2788 

Lobato, E., Geraldes, M., Melo, M., Doutrelant, C. and Covas, R. 2017. Diversity and composition of cultivable gut bacteria in an endemic island bird and its mainland sister species. Symbiosis 71: 155-164. http://dx.doi.org/10.1007/s13199-016-0419-6 

Loiseau, C., Melo, M., Lobato, E., Beadell, J.S,, Fleischer, R.C., Reis, S., Doutrelant, C. and Covas, R. 2017. Insularity effects on the assemblage of the blood parasite community of the birds from the Gulf of Guinea. Journal of Biogeography 44: 2607–2617. http://dx. doi: 10.1111/jbi.13060

Mares, R., Doutrelant, C., Paquet, M., Spottiswoode, C.N., and Covas, R. 2017. Breeding decisions and output are correlated with both temperature and rainfall in an arid-region passerine, the sociable weaver Royal Society Open Science 4: 170835. http://dx.doi.org/10.1098/rsos.170835 2016

Doutrelant, C., Paquet, M., Renoult, J.P., Grégoire, A., Crochet, P-A., and Covas, R. 2016. Worldwide patterns of bird colouration on islands. Ecology Letters 19: 537-545. http://dx.doi.org/10.1111/ele.12588

Lobato, E., Geraldes, M., Melo, M., Doutrelant, C. and Covas, R. 2016. Diversity and composition of cultivable gut bacteria in an endemic island bird and its mainland sister species. Symbiosis. http://dx.doi.org/10.1007/s13199-016-0419-6

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.

Aucker, 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 (*These two authors contributed equally to this study)

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. PLoS ONE 8(3): e59336.

Van Dijk, R.E., Kaden, J.C., Argueelles-Tico, 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.

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 Behaviour 81:121-126.

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.

Beadell, J.S., Covas, R., Melo, M., Ishtiaq, F., Perkins, S.L., Graves, G.R.. and Fleischer, R.C. 2009. Host associations and evolutionary relationships of avian blood parasites from West Africa. International Journal of Parasitology: 39: 257-266.