Abundance and community composition of small mammals in different habitats in Hugumburda forest, northern Ethiopia

ADAM, M.; WELEGERIMA, K.; MEHERETU, Y. 2015. Abundance and community composition of small mammals in different habitats in Hugumburda forest, northern Ethiopia. International Journal fo Biodiversity and Conservation 7(2):119-125. doi: 10.5897/IJBC2014.0787

Abstract. Tropical forest ecosystems harbor several species of small mammals. Diversity and abundance of small mammals in these forests reflect the quality and diversity of the ecosystems. The corrent study was carried out to assess abundance and species composition of small mammals (rodents and shrews) in three habitat types (Pterolobium, Juniperus and Cadia habitats) in Hugumburda forest, a dry afromontane forest in the Tigray region of North Ethiopia. The habitat types were selected based on the floristic compositions (plant species diversity) and level of human disturbance. All together, 179 individual small mammals belonging to seven rodent and one insectivore species were captured in 4,320 trap nights. The rodent species, with their relative abundance, were Stenocephalemys albipes, 55 (30.7%); Mastomys awashensis, 53 (29.6%); Arvicanthis dembeensis, 26 (14.5%); Lophuromys flavopunctatus, 22 (12.3%); Mus (Nannomys) setulosus, 14 (7.8%); Arvicanthis abysinicus 4 (2.2%); Dendromus mystacalis, 3 (1.7%) and the insectivore Crocidura olivieri, 2 (1.1%). There was significant variation in the small mammal abundance among the habitat types (X²= 29.45, P= 0.009), with more individuals caught in Pterolobium habitat, which has relatively highest plant species composition and lowest human disturbance than the other two habitats. The highest small mammal species diversity was also recorded in this habitat (H'= 1.76). Vegetation diversity and level of human interference are likely the major factors affecting small mammal abundance and composition in Hugumburda forest.

Arboreal tropical forest vertebrates: current knowledge and research trends

KAYS, R.; ALLISON, A. 2001. Arboreal tropical forest vertebrates: current knowledge and research trends. Plant Ecology 153:109-120.

Abstract. We review the ecology and specialized methods required for studying arboreal mammals, birds, reptiles and amphibians, and use faunal checklists from 12 tropical wet forest sites and an analysis of all articles published during the past ten years in 14 major journals to assess current knowledge and general research trends for these groups. The percentage of arboreal vertebrates was remarkably similar at the different sites (76.2+/-3.9%). Birds were the most arboreal group and amphibians and reptiles the least. The review of journals showed that primates were overwhelmingly the most studied group (336 papers), followed by bats (105), passeriform birds (73) and rodents (55). Judging by their portion of the arboreal vertebrate community and the number of papers surveyed, birds and amphibians and reptiles are vastly understudied compared to mammals, but this is largely due to the great number of primate studies. The number of publications on arboreal vertebrates has remained relatively stable over the last 10 years for all taxa except primates, which have seen a growth in publications. Canopy vertebrates from Brazil had by the most publications (120), followed by Madagascar (61), Costa Rica (55) and Indonesia (42). We conclude by highlighting the priorities we see for future studies on tropical canopy vertebrates.

The Brazilian Caatinga in South American zoogeography: tropical mammals in a dry region

MARES, M.A.; WILLIG, M.R.; LACHER JR., T.E. 1985. The Brazilian Caatinga in South American zoogeography: tropical mammals in a dry region. Journal of Biogeography 12:57-69.

Abstract. Recent research in South American biogeography on groups other than mammals suggests that the semi-arid Caatinga of northeastern Brazil provided xeric refugia during mesic phases of the Pleistocene climatic cycles. If this supposition is correct, the Caatinga mammal fauna might be expected to contain numerous species showing a pronounced level of adaptation to aridity and the origins of a substantial segment of the fauna slr~ould be traceable to the diversification and eventual speciation that would be expected to have resulted from extended isolation in a xeric environment. An analysis of the extant mammal fauna fails to corroborate these predictions; only one endemic mammal species is found in the Caatinga, and the fauna lacks the expected physiological and morphological adaptations. Other vertebrate groups also exhibit low levels of endemism. The high degree of climatic unpredictability that is characteristic of the Caatinga may preclude the development of a unique fauna adapted to xeric conditions. It appears that the present inhabitants of the region avoid the environmental effects of aridity and climatic unpredictability during harsh periods by utilizing the numerous mesic enclaves scattered throughout the Northeast. Indeed, even during periods of elevated precipitation, most mammal species reach their highest density in these relatively restricted areas. Although the Caatinga contains a xeric-adapted flora, it harbours an anomalous mammal fauna that is more characteristic of a mesic tropical biome in terms of both species composition and overall adaptation. The development of an assemblage of vertebrates whose adaptations do not parallel those of the dominant flora in a region is an unusual situation which should be of particular interest to palaeontologists attempting to reconstruct ancient environments.

Holocene vegetation chance and the mammal faunas of South America and Africa

VIVO, M.; CARMIGNOTTO, A.P. 2004. Holocene vegetation chance and the mammal faunas of South America and Africa. Journal of Biogeography 31:943-957.

Abstract
Aim. Although sharing many similarities in their vegetation types, South America and Africa harbour very dissimilar recent mammal faunas, not only taxonomically but also in terms of several faunistic patterns. However late Pleistocene and mid-Holocene faunas, albeit taxonomically distinct, presented many convergent attributes. Here we propose that the effects of the Holocene climatic change on vegetation physiognomy has played a crucial role in shaping the extant mammalian faunistic patterns.
Location. South America and Africa from the late Pleistocene to the present.
Methods. Data presented here have been compiled from many distinct sources, including palaeontological and neontological mammalian studies, palaeoclimatology, palynology, and publications on vegetation ecology. Data on Pleistocene, Holocene and extant mammal faunas of South America and Africa allowed us to establish a number of similar and dissimilar faunistic patterns between the two continents across time. We then considered what changes in vegetation physiognomy would have occurred under the late Pleistocene last

glacial maximum (LGM) and the Holocene climatic optimum (HCO) climatic regimes. We have ordained these proposed vegetation changes along rough physiognomic seral stages according to assumptions based on current botanical research. Finally, we have associated our hypothesized vegetation changes in South America and Africa with mammalian faunistic patterns, establishing a putative causal relationship between them.

Results. The extant mammal faunas of South America and Africa differ widely in taxonomical composition; the number of medium and large species they possess; behavioural and ecological characteristics related to herbivore herding, migration and predation; and biogeographical patterns. All such distinctions are mostly

related to the open formation faunas, and have been completely established around the mid-Holocene. Considering that the mid-Holocene was a time of greater humidity than the late Pleistocene, vegetation cover in South America and Africa would have been dominated by forest or closed vegetation landscapes, at

least for most of their lower altitude tropical regions. We attribute the loss of larger-sized mammal lineages in South America to the decrease of open vegetation area, and their survival in Africa to the existence of vast savannas in formerly steppic or desertic areas in subtropical Africa, north and south of the equator. Alternative explanations, mostly dealing with the disappearance of South American megamammals, are then reviewed and criticized.

Main conclusions. The reduction of open formation areas during the HCO in South America and Africa explains most of the present distinct faunistic patterns between the two continents. While South America would have lost most of its open formations within the 30 latitudinal belt, Africa would have kept large areas suitable to the open formation mammalian fauna in areas presently occupied by desert and semi-arid vegetation. Thus, the same general climatic events that affected South America in the late Pleistocene and Holocene also affected Africa, leading to our present day faunistic dissimilarities by maintaining the African mammalian communities almost unchanged while dramatically altering those of South America.