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New insights into the ecology of the dodo using a multidisciplinary approach

Periodic Reporting for period 1 - NINEDOMA (New insights into the ecology of the dodo using a multidisciplinary approach)

Reporting period: 2018-10-01 to 2020-09-30

The Dodo, Raphus cucullatus, is an enigmatic bird endemic to Mauritius, in the Indian Ocean. This bird was discovered in 1598 by Dutch sailors. Less than one hundred years later, at the end of the 17th century, the Dodo became extinct. Being thought of as fat and stupid-looking bird, the Dodo is famous in popular culture, appearing in paintings, books, and movies from its discovery until today. More importantly, the Dodo is one of the first species known to have been driven to extinction because of human activity. Although it was contemporaneous with humans for decades, and extinct for only three hundred years, we know very little about its ecology. Understanding the biology of the Dodo is important because it is such an iconic example of human-induced extinction. Therefore, new information about these birds is crucial. With current concerns about biodiversity and conservation effort, it is essential to understand why some species are more prone to extinction than others – and that requires an understanding of all aspects of their biology, including diet, reproduction, population structure, locomotion, habitat preference, and geographic distribution of key species driven to extinction already by human activity. The Dodo was the largest terrestrial animal in its ecosystem. Understanding of its ecology is, therefore, crucial to understand the Mauritius ecosystem before the arrival of humans and to estimate the real impact of human activity on this island. Furthermore, because the Dodo is an icon of extinction, determining aspects of its (palaeo)biology on the basis of objective evidence and quantitative methods will be a test case of methods of inference and also should attract wide public interest.

I hereby propose to study the ecology of the Dodo, including diet, locomotion, and population structure. To these ends, I propose to apply a novel multi-angle combination of scientific methods. This will bring us new insights into the ecosystem of Mauritius before the arrival of humans and a better understanding of the role played by humans in the extinction of the Dodo. The study will be extended to the Columbiformes in general to gain a better understanding of the evolution of this group. Finally, a comparison with the Solitaire will be conducted to test if these two birds - which were contemporaneous in two close islands in the Mascarenes and which became extinct at the same time - had the same ecological adaptations.
So far several parts of the project have been done in parallel:
- study of the locomotion:
The study of the locomotion will be done using the bone measurements of the maximal length and the minimal width of the tarsometatarsus. To this end, I used 3D models of these bones in order to use an automatic tool that I am developing to obtain these two values automatically from the 3D models. So far I have obtained 158 3D scans for tarsometatarsus, both from photogrammetry and 3D surface scan. These bones have been measured as well to validated the new tools that I am developing.

- study of the diet:
The study of the diet will be done using two different complementary approaches: a biomechanical Finite Element Analysis (FEA) and an isotopic geochemical analyses including carbon, oxygen and sulfur stable isotopes.
So far, I have obtained a beautiful ct-scan of the unique complete dodo skull from Oxford, and I am working on the scan to prepare the model for the FEA analysis. I have also done a ct-scan of a complementary composite dodo skull form the Natural History Museum in Paris, which will be compared with the skull from Oxford. Within the next couple of months, the two skulls will be ready to be used in the FEA model. Unfortunately, due to the-covid issues, it has been impossible to sample any seeds, but we will use the published data of seeds hardness as an input in our FEA models.
For the isotopes part, all the sampling has been done, corresponding to a unique 68 specimens from the unique site la Mare aux Songes, including dodo samples as well as the associated fauna. Part of the analyses has been done already, and the end of the analyses will be done by the end of December 2020. These analyses correspond to carbon, oxygen and sulfur isotopes.

- study of the structure of the population:
The structure of the population will be addressed using two approaches: a study of 3D geometric morphometry and the bone histology.
The first part of the morphometric methods has been done using 42 complete tarsometatarsi which have been 3D scanned. The preliminary results show that there no difference between males and females. This results will be confirmed during the next couple of months applying the same method on the two other bones of the hindlimb (femora and tibiotarsus). This will be possible thanks to a large sample of dodo bones including 367 specimens, all 3D scanned.
If a difference is observed between the males and the females, a bone histological study will be performed to estimate which group corresponds to the females, as the females have a specific kind of bone tissue when they are ovulating.
Until the end of this project, I expected to have the paper about the locomotion published, as well as the paper about the sexual dimorphism and the population structure. Due to the covid issues, the paper about the diet will be delayed by a few months, as part of the isotopic analyses will be done only in the next couple of months.
reconstruction of a dodo