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.

Camera-trap study of ocelot and other secretive mammals in the northern Pantanal

TROLLE, M.; KÉRY, M. 2005. Camera-trap study of ocelot and other secretive mammals in the northern Pantanal. Mammalia 69:3-4.

Abstract. Reliable information on abundance of the ocelot (Leopardus pardalis) is scarce. We conducted the first camera-trap study in the northern part of the Pantanal wetlands of Brazil, one of the wildlife hotspots of South America. Using capture-recapture analysis, we estimated a density of 0.112 independent individuals per km² (SE 0.069). We list other mammals recorded with camera traps and show that camera-trap placement on roads or on trails has striking effects on camera-trapping rates.

Riqueza de mamíferos de grande e médio porte do Parque Nacional da Serra do Divisor (Acre, Brasil)

CALOURO, A.M. 1999. Riqueza de mamíferos de grande e médio porte do Parque Nacional da Serra do Divisor (Acre, Brasil). Revista Brasileira de Zoologia 16(2):195-213.

Abstract. The richness of the large and medium-sized mammals of the Serra do Divisor National Park (Acre, Brazil). The objective of the present study was to characterize the richness (number of species) of large and medium-sized mammals, and the antropic threats in the Parque Nacional da Serra do Divisor (PNSD). In 31 days data were collected through direct observations or evidences (bones, hairs, vocalizations and tracks) along pre-existing trails distributed in different types of vegetation. Wild mammals captured by local people were also considered. They were found 44 species of terrestrial mammals (with the exception of small mammals and bats) and two species of cetaceans, representing 73% of the total predicted, according to the literature and information of local dwellers were registered in PNSD. They exist in the are two species classified by IUCN (1996) as "Endangered" [Cacajao calvus rubicundus (I. Geoffroy, 1806) and Priodontes maximus (Kerr, 1792)] and five as "Vulnerable" [Ateles chamek (Humboldt, 1812), Callimico goeldii (Thomas, 1904), Lagothrix lagotricha poeppigii (Humboldt, 1812), Myrmecophaga tridactyla Linnaeus, 1758 and Inia geoffrensis (Blainville, 1817)]. Given that subsistence and commercial hunting are common in the PNSD, mammals more affected by hunting [Ateles chamek (Humboldt, 1812), Lagothrix lagotricha (Humboldt, 1812), Tayassu pecari (Link, 1795)] were observed only in the more remote areas such as Serra do Divisor, Rio Moa. In comparison with others areas, the results indicate that PNSD has high richness of the mammals, with special attention to the 14 primates species registered.

Interactions between short-beaked common dolphin (Delphinus delphis) and the winter pelagic pair-trawl fishery off Southwest England (UK)

BOER, M.N.; SAULINO, J.T.; LEOPOLD, M.F.; RIJNDERS, P.J.H.; SIMMONDS, M.P. 2012. Interactions between short-beaked common dolphin (Delphinus delphis) and the winter pelagic pair-trawl fishery off Southwest England (UK). International Journal of Biodiversity and Conservation 4(13):481-499. doi: 10.5897/IJBC12.016

Abstract. During offshore and onshore studies (2004 to 2009), the interactions between pair-trawls and shortbeaked common dolphins (Delphinus delphis) were studied to better understand the impact of bycatch. A ‘hotspot’ area where pair-trawls overlapped with high dolphin abundance was identified. We made comparisons between boat-based data collected in absence and presence of pair-trawlers. The relative abundance and group-size of dolphins was significantly higher in the presence of pair-trawlers. Dolphins were observed associating with towing and hauling procedures. Significantly, more carcasses occurred in areas with hauling-activity than those without. Body-temperatures obtained from carcasses found near operating pair-trawlers indicated that bycatch mostly occurred at night. During necropsy studies, difficulties were encountered in identifying the fishing-gears responsible. Strandings data highlighted that the number of dead stranded dolphins was probably much higher than previously reported and there was a significant difference in the age and gender-composition of carcasses. Mature/sub-adult males appeared at greater risk from entanglement in pair-trawls offshore, whilst females with young appeared more vulnerable to inshore gillnets. Our findings show that the overlap between pelagic fisheries and the common dolphin hotspot is causing direct mortality through bycatch and, together with recent range-shifts, may have contributed to a localised decline of this species in this winter hotspot since 2007.

Using the dead to monitor the living: can road kill counts detect trends in mammal abundance?

GEORGE, L.; MACPHERSON, J.L.; BALMFORTH, Z.; BRIGHT, P.W. 2011. Using the dead to monitor the living: can road kill counts detect trends in mammal abundance? Applied Ecology and Environmental Research 9(1):27-41.

Abstract. Counts of animal corpses resulting from road traffic collisions can give useful information on changes in animal abundance if there is a correlation between the population density of the species in neighbouring habitats and the number of road kills observed. Collection of data on mammal road casualties can be carried out by untrained volunteers; it can be collected across large areas; and it is cost effective in terms of time and expense. We carried out a study to determine if road casualty data can be used to monitor mammal abundance and distribution using one of the most commonly recorded road casualty species in the UK, the rabbit (Oryctolagus cuniculus), as an example. We found a direct relationship between the numbers of rabbit road casualties and the numbers living in the wider landscape. Nearly 60% of the deviance in the live rabbit density index could be explained using only rabbit road casualty, landclass group and traffic flow data. Therefore the use of road casualty data is a cost effective method of monitoring rabbits and, by implication, other species over a large area in the UK, and is a highly effective means of monitoring terrestrial mammals.

Rarity in Neotropical bats: correlations with phylogeny, diet, and body mass

ARITA, H.T. 1993. Rarity in Neotropical bats: correlations with phylogeny, diet, and body mass. Ecological Applications 3(3):506-517.

Abstract. Bats are an important component of tropical faunas, both in terms of number of species and total biomass. Very little information, however, is available on the status and conservation of this diverse group. To contribute to the solution of this problem, rarity among Neotropical bats was analyzed using a set of 150 species. Rarity was quantified by local abundance and area of distributional range and by a combined index of rarity created by compounding these two variables. Nested analyses of variance showed local abundance to be more variable among genera than at any other taxonomic level, and area of distribution to be more variable among species. No significant correlation with body mass was found for local abundance or for area of distribution. Similarly, no correlation was found between distribution and abundance. Local abundance, but not area of distribution, varied significantly among taxonomic and trophic categories. At the local level, bats of the family Molossidae tend to be less abundant than other species. Bats that feed on plant parts or products (fruit, nectar, and pollen) are more abundant than insectivores and carnivores. The distribution of species among Rabinowitz' categories of rarity varied among taxonomic and trophic groups. The classification of rarity and the combined index of rarity introduced here can be used as guidelines for the identification of vulnerable species.

Camera trapping for jaguar (Panthera onca) in the Tuichi Valleys, Bolivia

WALLACE, R.B.; GOMEZ, H.; AYALA, G.; ESPINOZA, F. 2003. Camera trapping for jaguar (Panthera onca) in the Tuichi Valleys, Bolivia. Mastozoología Neotropical 10(1):133-139.

Abstract. Camera trapping techniques, in combination with robust mark-recapture statistics, have been used extensively in Asia to provide tiger population density estimates and relative abundance information. Here we present the results of a first attempt to use these methodologies to determine jaguar abundance. Results suggest a relatively low jaguar population density. Nevertheless, it is hypothesized that previous human disturbance at the site may be responsible for this situation, thereby underlining the need for further studies of this nature.

Rarity in neotropical forest mammals and its ecological correlates

ARITA, H.T.; ROBINSON, J.G.; REDFORD, K.H. 1990. Rarity in neotropical forest mammals and its ecological correlates. Conservation Biology 4(2):181-192.

 Abstract. Local density and size of distributional range have been used to characterize rarity, but conclusions are weakened by their possible lack of independence. The usefulness and validity of using these two variables were tested with data on distribution, local density, body size, and feeding habits for a set of 100 Neotropical forest mammals.
In a bivariate plot of distributional range against local density, species clustered according to their trophic or taxonomic groups. This indicates that diet and phylogenetic history have an influence on rarity. A negative correlation was found between distribution and abundance. However, this correlation was weaker within trophic or taxonomic groups, and vanished when body size was held constant. These results show that both distribution and abundance are valid and independent estimators of rarity when comparing species with similar sizes and ecological traits. Regression analysis showed that larger animals tend to have lower densities and wider distributional ranges. Rarity is clearly associated with body size.
A dichotomous classification of rarity based on area of distribution and local density is suitable for Neotropical forest mammals. Species in each of four categories created by such a scheme require different conservation and management policies that are determined by the ecological characteristics of the spcies. Final conservation strategies must also be shaped by political and economic constraints.

Variação espacial e influência do habitat na estrutura de comunidades de pequenos mamíferos em áreas de campo rupestre no Distrito Federal

SANTOS, R.A.L.; HENRIQUES, R.P.B. 2010. Variação espacial e influência do habitat na estrutura de comunidades de pequenos mamíferos em áreas de campo rupestre no Distrito Federal. Biota Neotropica 10(1):31-38.

Abstract. In the present study, we investigated the communities of small mammals in rocky fields in the Federal District. We examined the composition, abundance and richness and their relation to the structure of the habitat and if there is significant spatial variation in species composition among sites of rocky fields. Small mammals were sampled by live-trapping techniques in seven sites. The total effort for the seven sites was 5.680 trap-nights; we captured 157 individuals in eight species of rodents. Calomys tener and Cerradomys scotti were the most abundant species in the study sites, with 47.1 and 18.0% of total individuals, respectively. The results showed that the areas of rocky fields of the Federal District have a fauna of small mammals (average of four, range of variation of three to five species), comparable to other Cerrado physiognomies. The complexity of the habitat proved to be a major determinant in the composition of communities of small mammals in rocky fields. There was a distinction between communities of small mammals of the sites of APA Gama e Cabeça do Veado and the sites of the APA de Cafuringa. There was influence of the distance between the places on the composition of species with decreasing similarity with increasing distance among sites. The differences in environmental conditions, the structure of the habitat and the fact that it was possible two biogeographical regions may explain the faunal differences between the two regions.

Estimating the abundance of mouse populations of known size: promises and pitfalls of new mothods

CONN, P.B.; ARTHUR, A.D.; BAILEY, L.L.; SINGLETON, G.R. 2006. Estimating the abundance of mouse populations of known size: promises and pitfalls of new mthods. Ecological Applications 16(2):829-837.

Abstract. Knowledge of animal abundance is fundamental to many ecological studies. Frequently, researchers cannot determine true abundance, and so must estimate it using a method such as mark–recapture or distance sampling. Recent advances in abundance estimation allow one to model heterogeneity with individual covariates or mixture distributions and to derive multimodel abundance estimators that explicitly address uncertainty about which model parameterization best represents truth. Further, it is possible to borrow information on detection probability across several populations when data are sparse. While promising, these methods have not been evaluated using mark–recapture data from populations of known abundance, and thus far have largely been overlooked by ecologists. In this paper, we explored the utility of newly developed mark–recapture methods for estimating the abundance of 12 captive populations of wild house mice (Mus musculus). We found that mark–recapture methods employing individual covariates yielded satisfactory abundance estimates for most populations. In contrast, model sets with heterogeneity formulations consisting solely of mixture distributions did not perform well for several of the populations. We show through simulation that a higher number of trapping occasions would have been necessary to achieve good estimator performance in this case. Finally, we show that simultaneous analysis of data from low abundance populations can yield viable abundance estimates.