In 1665, while serving as a soldier for the Dutch East India Company (VOC), Joannes Pretorius (1642-1694) sailed on the Nuissenburgto to the Cape of Good Hope, South Africa. Shortly after landing, he departed on the Hoogcarspel for Mauritius, a small island east of Madagascar in the Indian Ocean, serving as a ziekentrooster—a crucial role providing comfort to the sick and teaching children. The overall journey occurred between June 27 and July 30, 1666.

Regarded as a gifted and well-educated man, Joannes spent three years on the island of Mauritius (1666 to 1669), keeping a diary in which he meticulously noted his observations of the local fauna and flora. Little did he know, some of these written observations would become the only known natural history data for several of these animals, as many endemic species on the island would go extinct due to the impact of early sailors. Sailors introduced invasive species like rats, and also fed on native animals, leading to the decline and extinction of many species. Much of Joannes's notes focused on the native fauna and the effects of introduced animals.

Departing Mauritius on the Voerman on December 15, 1669, Joannes spent much of his time on this journey adding more natural history notes to his journal. Upon arriving in South Africa, he found employment in the VOC council secretary's office in the Cape. He spent the rest of his life in the Western Cape, establishing himself as a notable farmer with a diverse agricultural and livestock operation, and he passed away on April 30, 1694.

His journal remained unknown to science for centuries to come.

In 2023, Dr. Robert Curry at Villanova University led the Genealogy and Kinship course that I enrolled in. One assignment required looking into my deep family history through various means. This project led me to the discovery that Joannes Pretorius is, in fact, my 10th great-grandfather. I was able to determine this through traditional and genetic genealogy. Supporting lineages on this line with DNA matches across the globe, along with birth certificates and many other documents linking to him. Learning more about this relationship, and his travels and findings proved to be a rather exiting part of the assignment. A relative of mine had the opportunity to observe, document, and make a mark in history as a important naturalist. Observing into Natural History behaviour, exploring new areas, and making novel observations in the field is my passion. A slightly obsessive passion, and one that my brother shares. Although this is not a hereditary trait, I hope that this trend remains in our family.

The discovery of Joannes Pretorius’s journal came centuries later. The authors Hume & Winters (2016) put together a publication addressing his findings and the importance of them.

Notable work in his journal

• He provided the first information about the ecology and diet of the extinct Mauritian giant tortoises (Cylindraspis triserrata).

• Made not on the natural history of the the Raven Parrot (Lophopsittacus mauritianus); Mauritius Red Rail (Aphanapteryx bonasia); Mauritius Blue Pigeon (Alectroenas nitidissima); Mauritius Sheldgoose (Alopochen mauritiana); and the Dodo (Raphus cucullatus).

• Described how to keep Mauritian bird species in captivity. 

• He mentions how difficult it was to catch different species of parrot. 

• He made to first account about the ecology of the Mauritian sheldgoose (Alopochen mauritiana), nothing was known before.

My 10th great-grandfather contributed to the understanding of the Mauritian environment and several of its now extinct fauna. His writings offer valuable insights into the native animals and the impact of introduced animals on the island. His documentation on the care of Mauritian bird species in captivity is particularly noteworthy. As I progress in my science career, I take inspiration from his keen interests in natural history and aim to always keep in mind the importance of taking notes on observations during my travels. The future value of such notes could be exponential.

Further reading

Hume, J. P., & Winters, R. (2016). Captive birds on Dutch Mauritius: bad-tempered parrots, warty pigeons and notes on other native animals. Historical biology, 28(6), 812-822.

Pretorius, F. J. (1988). Johannes Pretorius, die stamvader van die Pretoriusse van Suid-Afrika, se jare op Mauritius: 1666-1669: II. Historia, 33(1), 112-122.