Rats of the genus Rattus (especially R. norvegicus the brown rat and R. rattus the black rat) and mice of the genus Mus (especially Mus musculus the domestic mouse) are unanimously recognized as among the “worst” invasive alien species globally. In West Africa, these three species show differential success according to syntheses at the continental level, with the black rat being much more widespread than the domestic mouse, and the brown rat being even less common. Brought to the coasts by sailing ships for centuries, they first settled in coastal colonial trading posts before penetrating inland areas following the main transport routes for goods and people, be they rivers, railways or roads. This scenario has been well documented in Senegal where the invasion routes of the black rat and the domestic mouse, their distribution in the country, and their coexistence with native species within commensal small mammal communities, are now well known. Data of this kind have also been collected in Niger and Benin by CBGP teams and their local partners
In this frame, the dataset presented here aims at providing information on the commensal small mammal community of the city of Bamako in Mali, a landlocked country of West Africa depending on exchanges with surrounding countries (including Senegal and Benin, among others) for its supplies. It corresponds to the results obtained during 14 trapping campaigns (one week each) that took place between October 2021 and March 2023 in Bamako, capital-city of Mali. The data gathered enable to tackle various questions regarding interactions between native and invasive species, as well as their impacts in various fields, including as reservoirs of zoonotic diseases.
Elements of the trapping procedures followed here have already been described elsewhere. Briefly, two types of live traps were used: locally made wire-mesh live traps and Sherman folding box traps. Traps were set (in pairs) inside housing or working units including inner yards, between one and three consecutive nights. They were checked and (re)baited once a day with peanut butter spread on a slice of fresh onion. All trap location were precisely geo-referenced and elements of habitat were systematically characterized (room type, presence of food potentially attractive for small mammals, construction materials of floor, walls and ceiling).
The sampled area corresponds to the district of Bamako, as delimited until 2023. Two quarters per commune in the four communes of the Niger River’s left bank and three quarters per commune of the right bank were selected, to account for the larger size and population of the right bank communes. Quarters were selected as to be representative of intra-communal diversity in terms of urbanization and socio-economic characteristics, without being too close from each other in order to ensure good spatial coverage of the city. In the quarters that were large enough (i.e. most of them), two distinct sectors were sampled, separated by at least a few hundred metres from each other. The sampled housing units were chosen at random, with a spacing between them of at least 50m.
The whole represents a total effort of 8092 trapnights, that yielded 1438 captures of small mammals. More than 83% of them were rodents, including invasive (Rattus norvegicus, Rattus rattus and Mus musculus) and native (Mastomys natalensis, Cricetomys gambianus) species. The remaining captures were of the shrew Crocidura olivieri.
(2024-02-05)
