Rallus Linnaeus, 1758

Nascimento, Rafael S. & Silveira, Luís Fábio, 2024, Fossil and subfossil birds of Brazil, Zoologia (e 23079) 41, pp. 1-234 : 121-122

Rallus Linnaeus

375. † Rallus sp.

Holocene – PE Fig. 34D

“a medium-sized species of rail” – Olson 1977: 357.

Rallidae – Olson 1981: 483.

“saracura fóssil” – Sick 1984a: 250.

Rallidae – Alvarenga 1992: 254.

Rallidae – Alvarenga 1993a: 63–64.

“sub-fossil rail” – Sick 1993: 211.

Rallidae – Alvarenga 1997: 123.

“saracura fóssil” – Sick 1997: 296.

Rallus sp. – Carleton and Olson 1999: 55.

? Atlantisia sp. – Hume 2017: 116–117.

While theorizing on the absence of species of Atlantisia or another genus in South Atlantic islands, Olson (1973) speculated on the existence of a rallid species exterminated by man-introduced mammals in the Fernando de Noronha Archipelago ( Fig. 1.19) or in the Trindade Island before specimens could be obtained. He noted that a search for subfossil remains on these territories could provide interesting results. During an expedition to the Fernando de Noronha Island in 1973, Olson (1977, 1981) collected the remains of a medium-sized rallid in old beach dunes at the base of the Santo Antônio peninsula, along with other vertebrates, gastropods, and land crabs, of a probably late holocenic age. Most of the dune material was scattered and many specimens were well mineralized ( Olson 1981, Carleton and Olson 1999).

Most elements of the skeleton were found, associated with several individuals. It had reduced wings and may have been flightless but to a lesser extent than other species. Olson (1977, 1981) initially postulated that it did not seem to be referable to any genera of mainland Brazil and might have been a form of Atlantisia , a genus now represented only by Atlantisia rogersi from Inaccessible Island in the Tristan da Cunha Archipelago ( Taylor 1996). The remains were later associated with the genus Rallus ( Carleton and Olson 1999) .

The first mention of the archipelago’s fauna is found in the account of the disputed fourth voyage of the explorer Amerigo Vespucci (1454?–1512)—“ Lettera di Amerigo Vespucci delle Isole Nuovamente in Quattro Suoi Viaggi ” (1504), written in 1503, the year in which the discovery of the islands is generally attributed to ( Olson 1981, Carleton and Olson 1999). Vespucci described marine and land birds occurring in large numbers, “so guileless that they let themselves be taken in hand” and had “loaded a boat full of them”; he also mentioned reptiles and “very large rats” ( Carleton and Olson 1999: 47). The latter likely represents the now-extinct Noronhomys vespucci , described by Carleton and Olson from material discovered by Olson on his expedition. After Vespucci’s account, no biological survey on the islands would be made until the arrival of naturalists J.C. Branner in 1876 and H.N. Ridley in 1887 ( Carleton and Olson 1999). If the rail was among the terrestrial birds observed by Vespucci, the action of man in direct hunting, habitat alteration, and/ or in the introduction of predatory species of both eggs and adults ( Noronhomys vespucci was interpreted as predominantly herbivore) had a devastating effect on this bird, which evolved in isolation, leading to its extinction shortly afterward, as happened with several other rallids on islands across the planet.

The complete description of the material, deposited at the Smithsonian Institution (Washington, D.C.) ( Hume 2017), is still pending. Olson passed away in January 2021, but in 2015–2016 personal communications with us expressed that the description was something he should have attended to long ago. After revising his ideas on Atlantisia , he reasserted that the rail of Fernando de Noronha is most likely a derivate of Rallus , as are all the fossil rails from the North Atlantic found so far ( Bermuda and the Macaronesian Islands of Azores and Madeira), so this widely dispersing genus probably made it across the Equator to Fernando de Noronha. The fossils were never depicted, but Olson commented that its bill is of medium length, not extremely elongated as in some species of Rallus , such as the larger ones, probably similar to the extinct Macaronesian Islands rallids eventually described by Alcover et al. (2015) but perhaps a little stouter. He also noted that almost none of the known fossil material from Fernando de Noronha has been cataloged or numbered yet. Additionally, regarding the age of the total material from the site, he noted that most of the fossils are indeed probably holocenic, although some, from their geological context, are almost certainly pleistocenic, but they are few and not particularly important.

On the absence of rallid remains in Trindade, Olson (1981) noted it is very unlikely that no endemic species existed there in the past, given the ample habitat and that these birds have successfully colonized all the other South Atlantic islands. Possibly, he did not find any remains because he was unlucky in his prospections, with the action of land crabs also reducing the chances of any carcass surviving long enough to be preserved, despite land crabs also occurring in Fernando de Noronha. The absence of resident Procellariiformes even in the fossil record of Fernando de Noronha may also be attributed to this predatory action on their nests, making reproduction very difficult or impossible.