Small mammals, particularly rodents, play an important role in food webs and ecosystem dynamics; however, when their populations explode, they can cause damage to crops or stored goods, and under certain circumstances, pose significant risks to human health. Thus, these small mammals (rodents and marsupials) are particularly useful for studying the impacts of environmental variables due to their importance in natural systems as seed dispersers, pollinators, and predators of arthropods, as well as food sources for carnivores, birds of prey, and reptiles [1].

Thanks to its rich and varied ecosystem, the territory of the Republic of Guinea is home to countless plant and animal species, including a wide variety of mammals. Rodents are animals sensitive to the environmental conditions of their habitat, and a change in these conditions can lead to the proliferation of a species. Furthermore, certain rodent species live in close proximity to humans, even in human habitats sometimes as pests, but also, in recent years, as pets. This proximity to humans, and the planet’s increasing urbanization are causes for concern, as these species carry diseases transmissible to humans, the incidence of which may increase significantly depending on changes in the living conditions of both these animals and humans [2].

Rodents interact with humans in ways that significantly influence the survival, distribution, and even proliferation of many of these species. At the same time, ecological changes in the environment including climate change, urbanization, deforestation, agricultural, and water management practices, significantly affect rodent population densities and spatial distribution, thereby facilitating their contact with humans [3].

Awareness of this loss of wildlife biodiversity due to hunting has led scientists from various disciplines to examine the issue of hunting and analyze wildlife conservation strategies [4]-[6]. The rapid population growth characteristic of sub-Saharan African countries is creating an imbalance between the demand for and supply of animal protein [7].

As a result, the natural resources that could ensure food security are under considerable human-pressure. In addition, climate change and desertification beyond unexpected agricultural disasters are making the population vulnerable and leading to the disappearance of flora and fauna [8].

According to [9], 47% of the world’s population lived in urban areas in the 2000s, and by 2030, this percentage will rise to 60%. Thus, the global urban population will reach 2.1 billion. Such an explosion will inevitably benefit commensal rodents, especially those in informal settlements lacking adequate sanitation, housing, and infrastructure [10].

Biogeographic studies of these organisms are of interest for species conservation because they provide a better understanding of their interaction with the environment [11].

In Guinea, most of our knowledge is based on the study conducted by [12]-[14]. The first authors report the collection of 674 specimens (300 complete specimens from the Nimba region itself and 374 skull specimens from owl pellets collected 100 km north of the subprefecture of Gouéké [12]-[14].

The fauna and distribution of various groups of small mammals in West Africa, and particularly in the Republic of Guinea, have been studied by numerous researchers [15]-[19]. The available publications address issues of zoogeography and the abundance of rodent and insectivore species in urban areas and their surroundings. However, there is insufficient literature on the distribution of rodents and insectivores. Questions regarding the seasonal distribution of small mammals and species dominance in different biotopes are also insufficiently addressed [15]-[20] (Figure 1).

Figure 1. Map of small mammal trapping expeditions in the Republic of Guinea (2017-2019), Sergey, Y./GLONASS GPS satellite [20].

Generalobjective

To study the distribution of small mammals and the seasonal dynamics of their abundance within the territory of the Republic of Guinea.

The sampling focused on small mammals encountered and captured in the various habitats surveyed. A total of 1220 small mammals were captured between December 6, 2017, and August 4, 2019, using snap traps or Sherman H.B. traps. Three families of rodents and insectivores were identified: the Muridae, the Nesomyidae, and the Soricidae. These families comprise 14 genera and species.

Table 1 shows the most frequently captured rodent and insectivore species: Mastomyserythroleucus 412 (33.77%) and the least frequently captured: Praomysderooi 2 (016%) as well as their dominance index.

Table 1. Distribution of small mammals captured during the survey.

Figure 4 shows a statistically significant difference between the dry season and the rainy season. In conclusion, fewer small mammals were captured during the dry season than during the rainy season.

Figure 4. Distribution of small mammals captured by season (P-value = 0.0002).

Table 2 shows that Mastomyserythroleucus 179 (31.02%), Rattusrattus 171 (29.63%), Musmusculus 99 (17.15%) and Mastomysnatalensis 50 (8.66%) were the most frequently captured and abundant species, while the least frequently captured were: Crociduraolivieri 26 (4.50%), Praomysdaltoni 13 (2.25%), Cricetomysgambianus 10 (1.73%), Musmusculoides 9 (1.55%), and Musminutoides 7 (1.21%). The least frequently captured species were: Gerbilliscusguinea 5 (0.86%), Arvicanthisansorgei and Lemniscomysstriatus 3 (0.51%) each, and Lophuromyssikapusi 2 (0.34%). The results obtained during the dry season are as follows: Mastomyserythroleucus 233 (36.23%), Rattusrattus 190 (29.54%), Mastomysnatalensis 71 (11.04%), Crociduraolivieri 45 (6.99%), and Musmusculus 40 (6.22%) were the most frequently captured and abundant species, while the least frequently captured species were: Praomysdaltoni 18 (2.79%), Cricetomysgambianus 13 (2.02%), Musminutoides 9 (1.39%), and Musmusculoides 7 (1.08%). Those captured in small numbers were represented by: Arvicanthisansorgei, Lemniscomysstriatus, and Lophuromyssikapusi, 4 (0.62%) each; Gerbilliscusguinea, 3 (0.46%); and Praomysderooi, 2 (0.31%). A comparision of the number of small mammals captured during the two seasons shows that significantly more captures occurred during the dry season than during the rainy season, which may be due to environmental conditions.

Table 2. Distribution of species caught by season and their dominance index.

Table 3 shows that more small mammals were captured in inhabited houses that in other habitats, with only a slight increase compared to forests.

Table 3. Distribution of small mammals captured by habitat, season, and trap type.

This analysis of Table 4 highlights the diversity of rodents and insectivores in the Republic of Guinea. The highest number of captures was recorded in Kindia, followed by N’zérékoré, Boké, and Kankan.

Table 4. Distribution of small mammals captured by region and trap types.

An analysis of Table 5 allowed us to identify three families of rodents and insectivores: Muridae, Nesomyidae and Soricidae. These families comprise 14 genera and species (Mastomyserythroleucus, Rattusrattus, Mastomysnatalensis, Crociduraolivieri, Musmusculus, Praomysdaltoni, Cricetomysgambianus, Musminutoides, Musmusculoides, Arvicanthisansorgei, Lemniscomysstriatus, Lophuromyssikapusi, Gerbilliscusguinea, Praomysderooi. Cricetomysgambianus should no longer be classified in the Muridae family but rather in the Nesomyidae family, within the Cricetomyinae subfamily.

Table 5. Distribution of small mammals captured by family and species.

The composition of rodent and insectivore populations across different habitats during our research was as follows: 14 species were recorded representing 3 families and one order.

Based on research conducted by [26] in certain areas of Guinea, 1660 rodents were found, comprising 11 species, including 997 Mastomysssp., 535 Musmusculus, 13 Musminutoides, 19 Praomystulbergi, 58 Rattusrattus, 6 Taterakempi, 22 Croceduraspp., 3 Dasymysincomtus, 2 Hyllomyscusalleni, 1 Malacomyslongipesssp., and 4 Uranomysssp.

Research conducted in 2021 by [27] led us to find 412 rodents belonging to 12 species.

The species encountered were: Mastomysspp. 167, Rattusrattus 166, Musmusculusspp. 22, Cricetomysgambianus 19, Crociduraspp.11, Lemniscomysstriatus 10. In contrast, the least frequently encountered are: Praomysrostratus 9, Pelomysfallax 2, Arvicanthisrufinus 2, Malacomysedvardsissp. 2, Lophuromyssikapusi 1, and Lophuromysansorgei 1.

When comparing our results to those reported by [28], a total of 587 rodents belonging to 18 species were captured: 299 Mastomysspp., 169 Rattusrattus, 37 Musmusculus spp., 24 Cricetomysgambianus, 16 Croceduraspp., 13 Musspp., 8 Praomysspp., 5 Hellosciurusgambiannus, 3 Myomysdaltoni, 3 Lophuromysansorgei, 2 Pelomysfallax, 2 Colomysgoslingi, 1 Otomystropicalis, 1 Arvicanthisabyssinicus, 1 Arvicanthisrumrutipallescens, 1 Lophuromyssikapusi, 1 Lemniscomysspp., and 1 Rattusnorvegicus. These species represent the bulk of the rodent fauna captured in the various habitats and locations surveyed in the prefecture of Kindia.

According to [29], the data collected in the various regions of Guinea were as follows: Forest Guinea: 738 specimens; Lower Guinea: 435 specimens; Upper Guinea: 427 specimens; and Middle Guinea: 255 specimens, for a total of 1,855 rodents representing 18 species.

For our study, we captured many more rodents during the dry season than during the rainy season, and food abundance in the capture areas may be an important factor affecting catch rates. The presence of Mastomys erythroleucus was notable in both seasons, whereas in African countries, contact between introduced and endemic commensal rodents dates back to the first half of the 20^th century and was not observed until later. The current situation in Guinea will allow us to monitor this competition in real time.

Changes in rodent populations are highly dependent on human use of the environment. Changes in farming practices and land left fallow are all conditions that favor rodent outbreaks. Species reported in certain localities were not encountered during this study. These would be either species for which our traps were not suitable, rare species, or species whose range lay outside the study area. In contrast, there are many more species during the dry season, when high densities of rodents are found in our homes, savannas, plantations, and coastal areas, as shown by these results.

In the Djurdjura region of Kabylie, [30] recorded 85 individuals over 4015 trap-nights (2.1%). In the Béni Abbès region, [31] trapped a total of 177 rodents over 5815 trap-nights (3.04%). In the El Bayadh region, [32] also recorded an average of 3.04 individuals per 100 trap-nights (for 1500 trap-nights). The highest trapping effort was recorded in the Touggourt region (six species) by [33], with 78 captures over 1422 trap-nights, or 5.48%.

In the city of Cotonou, the following three species were the most abundant: Muridae (59.77%), Rattusrattus (59.77%), and Mastomysspp. (8.6%). (13.5%), as well as a shrew, Crociduraolivieri (8.6%). The capture of a large number of Rattusrattus is linked to its wide global distribution [34] and its documented presence in other African cities, such as Kinshasa (DRC) [35], Makurdi (Nigeria) [36], Harare (Zimbabwe), and Niamey (Niger) [37]. The relatively high number of Mastomysspp. and Crociduraolivieri is confirmed by recent studies in Africa [38].

This is due in part to a constant availability of food and continuous reproduction. However, it should also be noted that Cricetomysgambianus should no longer be classified in the Muridae family but rather in the Nesomyidae family, subfamily Cricetomyinae. However, this study should be expanded across the entire territory of guinea to better characterize small mammal populations on a semi-quantitative basis, improve understanding of habitat-species relationships, and produce more accurate distribution maps.

Following our research conducted in the four natural regions of the Republic of Guinea on Composition of Species, Distribution of Rodents and Insectivores in the four natural regions of the Republic of Guinea, several specimens were captured and classified into different families and species. A total of 1220 small mammals were captured, representing three families and 14 species. Cricetomysgambianus should no longer be classified in the Muridae family but rather in the Nesomyidae family, within the Cricetomyinae subfamily. Rodent populations in our various habitats were generally abundant and exhibited greater seasonal fluctuations than wild populations. This is due in part to a constant food supply and continuous reproduction. In contrast, there are many more species of rodents in our inhabited areas, Forests with sparse undergrowth or savanna, Agricultural ecosystems (vegetable gardens and plantations), Coastal areas and Forests. However, this study warrants expansion across the entire territory of Guinea in order to better characterize small mammal populations primarily on a semi-quantitative basis to clearly understand the habitat-species relationships, and to produce more accurate distribution maps. Based on our observations, the overall health situation does not seem to be particularly concerning. However, the presence of potentially dangerous zoonotic diseases, particularly for healthcare professionals, should not be overlooked. These diseases are transmitted from one host to another when conditions are favorable, which highlights their dependence on ecosystem disturbances. It is therefore likely that these diseases and their vectors circulate across borders, thereby increasing the risk of human infection. Wild animals, particularly rodents, constitute a major reservoir of zoonotic pathogens. It is therefore essential to identify and understand the routes of transmission between wildlife and humans.

We extend our heartfelt thanks to the Directors of the Russo-Guinean Research Center for Epidemiology and Prevention of Infectious Diseases (CRRGEPMI), to the Guinean Institute of Applied Biological Research (GIABR), the Laboratory for Applied Research in Natural Sciences (LARASCINA), and to all the staff at GIABR and the University of Kindia for their efforts.

Conceptualization: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO, Abdoulaye BALDE.Datacuration: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO.Formalanalysis: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV.Investigation: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO, Abdoulaye BALDE, Mariama BAH, Souleymane DIALLO, Bonaventure KOLIE, Ibrahima GOURESSY, Alphonse Keller KONKON.Methodology: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO.Projectadministration: Sergey YAKOVLEV, Makhail KORNEEV, Aboubacar Hady TOURE.Supervision: Sergey YAKOVLEV, Aboubacar Hady TOURE.Validation: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO.Visualization: Namory KEITA.Editingoriginalproject: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO.Writingrevisionandediting: Namory KEITA, Sergey YAKOVLEV, Amara CISSE, Makhail KORNEEV, Aboubacar Hady TOURE, Raphael DORE, Ibrahima Baïlo DIALLO, Abdoulaye BALDE, Mariama BAH, Souleymane DIALLO, Bona venture KOLIE, Ibrahima GOURESSY, Alphonse Keller KONKON, Siba KALIVOGUI.