An ecology-based method for defining priorities for large mammal conservation: the tiger as case study

WIKRAMANAYAKE, E.D.; DINERSTEIN, E.; ROBINSON, J.G.; KARANTH, U.; RABINOWITZ, A.; OLSON, D.; MATHEW, T.; HEADAO, P.; CONNER, M.; HEMLEY, G.; BOLZE, D. 1998. An ecology-based method for defining priorities for large mammal conservation: the tiger as case study. Conservation Biology 12(4):865-878.

Abstract. The disappearance of large vertebrates in the tropical belt may be the next biological insult of the global extinction crisis. Large predators and their prey are at particular risk in Asia, where they are threatened by poaching and habitat loss. To facilitate the best use of limited conservation recources, we created and objective, ecology-based method for identifying priority areas for conservation that incorporates both habitat representation and landscape-level features. Using tigers as an example, our method captures the range of ecological habitats where they occur, accounting for ecological, demographic, genetic, and behavioural differences. Our analysis is hierarchical. We divided the tiger range into distinct bioregions and identified tiger habitat types within each. we then delineated tiger conservation units throughout the bioregions and ranked the units based on habitat integrity, poaching pressure, and tiger population trends. To maintain representation of tiger populations and their ecology in the different tiger habitats, we made comparisons only among tiger conservation units from the same tiger habitat types nested within the same bioregion. We identified 159 tiger conservation units in three bioregions - the Indian subcontinent, Indochina, and Southeastern Asia. We ranked the units in three categories that reflect the probability of long-term persistence of tiger populations (highest in level I units). Twenty-five tiger conservation units were classified as level I, 21 as level II, and 97 as level III. An additional 16 tiger conservation units for which little information is available were identified for immediate surveys. Levels I, II and those identified for immediate surveys are the priority areas for immediate funding and for a regional tiger conservation strategy. One feature emerging from the study showed that protected areas cover only small areas of tiger conservation units; If the long-term prospects for tiger conservation are to improve, poaching must be stopped and protected areas increased in number, linked, and buffered by natural habitats. To enhance landscape integrity, the priority tiger conservation units that straddle international borders should be managed as transboundary reserves, giving tiger conservation a stronger regional structure. Like tigers, populations of other wide-ranging mammalian carnivores and large herbivores also are declining due to poaching and loss of habitat. The method we present for tigers can be adapted readly to improve conservation strategies for these species as well.

The burrows of Dasypus hybridus Cingulata: Dasypodidae)

GONZÁLEZ, E.M.; SOUTULLO, A.; ALTUNA, C.A. 2001. The burrows of Dasypus hybridus Cingulata: Dasypodidae). Acta Theriologica 46(1):53-59.

Abstract. Dasypus hybridus (Desmarest, 1804) inhabits open fields in southern South America. Burrows of D. hybridus were cylindrical with a conical end. They had an entrance and a single tunnel without branches. Three locations of the burrows in the terrain were detected: in banks of dried waterways, near rocks, and in open field. The orientation of 29 burrow mouths was not random and, although they did not point to any cardinal point, in particular there was a strong tendency to avoid the south quadrant. In a sample area of 90 x 140 m, burrow mouths were arranged in a random spatial pattern with a density of 25.4 burrows por ha. Great variation in burrow length was found (118.8 +/- 105.69 cm, CV = 89.0%). Tunnels may be used as refuges and/or for thermo-regulation. The orientation of burrow mouths can also be related to thermoregulation as tunnels are covered from dominant winds, and, for many hours every day, the temperature at the mouths can be influenced by insolation. The possible existence of shelter-burrows and resting-burrows is discussed.

Analysis of the distribution patterns of southern right whale off the southern Brazilian coast

SANTO, S.E.; FRANCO, D.; GROCH, K. 2013. Analysis of the distribution patterns of southern right whale off the southern Brazilian coast. Neotropical Biology and Conservation 8(3):143-149.

Abstract. The southern right whale, Eubalaena australis, is a migratory baleen whale that uses southern Brazilian waters as a nursery and breeding ground from June to November. This study aims to determine the distribution patterns and main aggregation sites of southern right whales off the southern Brazilian coast from around Santa Catarina Island to Osório, and to investigate the population distribution according to the coastline and bathymetric features. The methods consisted in obtaining geographical coordinates for each individual, sighted through helicopter expeditions over a transect along the coastline, conducted once a year in September, from 2001 to 2010. This data was used to generate a density estimate surface map of southern right whales using the Kernel Density Estimator. Additionally, a digital bathymetry was overlaid to the density estimate map. The results pointed out a region of high density estimate of southern right whales, located from 28°12’22”S, 48°39’25”W to 28°33’58”S 48°47’19”W, respectively, from Imbituba to Santa Marta Cape. The largest aggregations were observed where the shelf declivity is higher, as a result from the bathymetric lines of 10 m and 40 m being closer to each other, and where the coastline shows great amount of bays. We highlight the importance of monitoring the southern right whales distribution patterns observed in this study, aiming to identify possible habitat changes that can be indicative of disturbances on their populations.

Variabilidade genética en géneros de ciervos neotropicales (Mammalia: Cervidae) según loci microsatelitales

RUIZ-GARCÍA, M.; MARTINEZ-AGÜERO, M.; ÁLVAREZ, D.; GOODMAN, S. 2009. Variabilidade genética en géneros de ciervos neotropicales (Mammalia: Cervidae) según loci microsatelitales. Revista de Biología Tropical 57(3):879-904.

Abstract. Genetic variability in Neotropical deer genera (Mammalia: Cervidae) according to DNA
microsatellite loci. Species conservation programs are highly based on analyses of population genetics. We compared eight Neotropical Cervidae (Mazama americana, M. gouzaoubira, M. rufina, Odocoileus virginianus, Hippocamelus antisensis, Pudu mephistopholes, Ozotoceros bezoarticus and Blastoceros dichotomus) and some European and Asian Cervidae (Cervus elaphus, C. nippon, Capreolus capreolus, C. pygargus and Dama dama). The European species C. elaphus was our standard for a high degree of genetic variability: we used a Scottish population originated in the mix of diverse Western European subspecies. On the contrary, Cervus nippon (a population from Scotland with a founder effect) was our standard for a depauperated population. The M. americana, M. gouzaoubira and O. virginianus samples had high diversity values close to our C. elaphus population (H= 0.64, 0.70 and 0.61, respectively), while M. rufina was very low, close to C. nippon. Several sample sets of Mazama and Odocoileus yielded a homozygote excess, probably due to the Wahlund (subdivison) effect. There was no evidence of recent bottleneck events.

Response of leopards to re-introduced tigers in Sariska Tiger Reserve, Western India

MONDAL, K.; GUPTA, S.; BHATTACHARJEE, S.; QURESHI, Q; SANKAR, K. 2012. Response of leopards to re-introduced tigers in Sariska Tiger Reserve, Western India. International Journal of Biodiversity and Conservation 4(5):228-236. doi: 10.5897/IJBC12.014

Abstract. Tigers got exterminated from Sariska Tiger Reserve before 2005. After that, five tigers were re-introduced to Sariska during 2008 to 2010. The present study compared the abundance, site occupancy and temporal activity pattern of leopard before and after tiger re-introduction. The population of leopard was estimated by mark-recapture technique using camera traps during 2008 to 2010 in an effective trapping area of 223.3 km2. Before tiger re-introduction (2008), the leopard density was estimated to be 7.6±0.6 (SE) /100 km2 and after tiger reintroduction it was 6.2±0.8 /100 km2(2009) and 3.1±0.4 /100 km2 (2010). It was observed that the density of leopard declined significantly (Two sample T-Test; P = 0.0002) from 2008 to 2010. Rate of site occupancy was calculated through site-wise capture history of leopard obtained from camera traps. Before tiger re-introduction the probability of site utilization of leopard was 0.75, while after tiger re-introduction probabilities of site utilization of leopard and tiger were estimated at 0.54 and 0.52 respectively and the co-occurrence of both the species was 0.51. Temporal activity patterns of tiger and leopard were investigated from photo captures. Prior to the release of tigers, mean activity time of leopard was 20: 57 h (95% CI 20: 19 to 22: 53) but shifted to 22: 35 h (21: 02 to 01: 25 h) after tiger release (Watson’s U2 test: p<0.005). The present study showed that there was a decline in the leopard population after tiger re-introduction and considerable segregation between the two carnivores along the spatial and temporal axes.

Rural roads as barriers to the movements of small mammals

MACPHERSON, D.; MACPHERSON, J.L.; MORRIS, P. 2011. Rural roads as barriers to the movements of small mammals. Applied Ecology and Environmental Research 9(2):167-180.

Abstract. Over the last 50 years increasing fragmentation of habitats has occurred due to road building. Fragmenting a large population into smaller ones can have a negative effect on population demography. In England much small mammal habitat occurs in suburban and rural areas where the majority of roads are either single track or two lanes, and traffic density is light. This study investigated the effect of minor roads on the movements of two small mammals, the wood mouse (Apodemus sylvaticus) and bank vole (Myodes glareolus). Capture-Mark-Recapture was used to study movements beside and across rural roads of two different widths. The results suggest that even small roads less than 6metres wide, with relatively little traffic, do act as partial barriers for these small mammals, reducing their movement between habitats on either side of the road. It is evident that island populations are being created as a result of road construction, even access roads within nature reserves.

Trend of the Yellowstone grizzly bear population

EBERHARDT, L.L.; BREIWICK, J.M. 2010. Trend of the Yellowstone grizzly bear population. International Journal of Ecology, v. 2010, Article ID 924197, 5 pages. doi: 10.1155/2010/924197.

Abstract. Yellowstone’s grizzlies (Ursus arctos) have been studied for more than 40 years. Radiotelemetry has been used to obtain estimates of the rate of increase of the population, with results reported by Schwartz et al. (2006). Counts of females with cubs-of-the-year “unduplicated” also provide an index of abundance and are the primary subject of this report. An exponential model was fitted to n = 24 such counts, using nonlinear leastsquares. Estimates of the rate of increase, r, were about 0.053. 95% confidence intervals, were obtained by several different methods, and all had lower limits substantially above zero, indicating that the population has been increasing steadily, in contrast to the results of Schwartz et al. (2006), which could not exclude a decreasing population. The grizzly data have been repeatedly mis-used in current literature for reasons explained here.

Do invasive fire ants affect habitat selection within a small mammal community?

HOLTCAMP, W.N.; WILLIAMS, C.K.; GRANT, W.E. 2010. Do invasive fire ants affect habitat selection within a small mammal community? International Journal of Ecology, v. 2010, Article ID 642412, 7 pages. doi: 10.1155/2011/642412.

Abstract. Animals must balance foraging with the need to avoid predators and risky habitats that decrease their fitness, and at the same time they must cope with competitors vying for habitat and resources. We examined how habitat selection and population density of four native small mammals were altered by the presence of red imported fire ants (Solenopsis invicta). When population size was low, hispid cotton rats (Sigmodon hispidus) and pigmy mice (Baiomys taylori) as well as white-footedmice (Peromyscus leucopus) used the “safe”, low fire ant habitat, as predicted by theories of density-dependent habitat selection. However, as fire ant population sizes expanded, cotton rats appeared to displace pigmy mice into the fire ant-dense grassland drainage while white-footed mice (Peromyscus leucopus) displaced all the other small mammals from low fire ant forest/brushland habitat.

A demo-genetic analysis of a small reintroduced carnivore population: the otter (Lutra lutra) in the Netherlands

SEIGNOBOSC, M.; HEMERIK, L.; KOELEWIJN, H.P. 2011. A demo-genetic analysis of a small reintroduced carnivore population: the otter (Lutra lutra) in the Netherlands. International Journal of Ecology, v. 2011, Article ID 870853, 11 pages. doi: 10.1155/2011/870853.

Abstract. Assessing the viability of reintroduced animal populations is a complicated task. Reintroductions are usually carried out with a small number of individuals, thereby, limiting the possibilities for monitoring because of the possible negative effects of intensive monitoring on survival and reproduction. Moreover, reintroduction studies are part of a socioeconomic interplay of forces, thereby, also limiting monitoring possibilities. Also, knowledge of population demography and abundance can be incomplete or unattainable. Here, we illustrate how we combined traditional telemetry and novel non-invasive genetic methodology to construct a detailed life table of a small reintroduced otter population in The Netherlands. Combining an appropriate capture-mark-recapture framework with a matrix modelling approach provides, in general, useful insights for such populations. The data indicated that (i) male survival is lower than female survival, (ii) the reintroduced population is currently growing (estimated λ = 1.26: range [1.06, 1.42]) and seems viable, (iii) increasing adult survival is currently the critical stage at which efforts of field managers should concentrate, and (iv) the modelling framework allowed us to determine the boundary conditions for the vital rates under which the population would go extinct. The applied approach directs at measurements that help field managers to implement the right conservation strategy after reintroductions.

Variação temporal da estrutura e tamanho de bandos de capivaras na Estação Ecológica do Taim, Rio Grande do Sul, Brasil

BAGER, A.; ROSA, C.A.; LOUREIRO, L.; CORRÊA, R.; CARMO, J.; GARCIAS, F. 2010. Variação temporal da estrutura e tamanho de bandos de capivaras na Estação Ecológica do Taim, Rio Grande do Sul, Brasil. Revista Brasileira de Zoociências 12(3):273-280.

Abstract. Temporal variation of structure and size of capybara groups in Taim Ecological Station, Rio Grande do Sul, Brasil. A capybara (Hydrochoerus hydrochaeris) population was monitored in a borderline region between ESEC Taim (Taim Ecological Station) and southernmost areas of rice cultivation, located in the state of Rio Grande do Sul (RS, Brazil). The aim was compared the structure and size of groups, in different seasons, with variations of temperature and precipitation during two years. A total of 25 censuses,  obtained through the direct count technique, were performed from August 2003 to August 2005. These samplings were performed in a transect of 4000-meter on the margins of Mangueira Lagoon. The capybaras were separated by age and sex. The average number of groups (NB) was of 24±0.65. The highest NB value was observed in spring of 2004 (29.7) and 2005 (26.2), as well as in the winter of 2005 (27.5), differing these seasons from the others (P<0.01). The average number of adults in the groups (NAB) was of 15.1±0.65 individuals. The NAB presented a strong negative relation with number of groups. This was observed in autumn, 2005 (P<0.001). The average number of individuals per groups (NTB) was of 26.3±1.10, and presented a temporal pattern similar to the adults. The correlation analysis between biotic factors (NB, NAB and NTB), and abiotic factors (temperature and precipitation) have not presented any significant values (P>0.05). The variations of structure observed in the groups are probably due to changes in the size of dry area  near the lake through the year, therefore resulting in different levels of approaching and grouping behaviors. The negative relation  between number of individuals per group and number of groups existing in the area reinforces the hypothesis of structural changes  of groups according to the period of the year.

Predicting presence and abundance of a small mammal species: the effect of scale and resolution

ORROCK, J.L.; PAGELS, J.F.; MCSHEA, W.J.; HARPER, E.K. 2000. Predicting presence and abundance of a small mammal species: the effect of scale and resolution. Ecological Applications 10(5):1356-1366.

Abstract. Management of small mammal communities in forest ecosystems requires a working knowledge of the scales at which species presence and abundance can best be predicted. Habitat-based models were developed to characterize the distribution of a boreal relict, the southern red-backed vole, Clethrionomys gapperi, in the southern Appalachian Mountains, USA, at three hierarchical scales of analysis. Vole presence and abundance were most evident at the high-resolution (macrohabitat) scale, followed by the intermediateresolution scale. The low-resolution model was the least effective for predicting presence or abundance and reflects the need for more resolute landscape classification systems if small mammal populations are to be accounted for in an ecologically relevant manner. Tree and shrub communities indicative of suitable vole habitat included Fraxinus pennsylvanica and Tsuga canadensis in the canopy and Carpinus caroliniana in the understory. Vole abundance increased with incidence of tree species such as Betula alleghaniensis, Pinus rigida, and Prunus serotina in the canopy, and Acer spicatum and woody vines in the understory. Voles were associated with northwest-facing high-elevation sites with abundant rocky substrate, likely a reflection of physiological water and thermal requirements, biogeographic influences, and the importance of substrate complexity for decreasing inter- and intraspecific interactions and avoidance of predators.
Identification of the most effective resolution of landscape characterization improves habitat-based models of C. gapperi population dynamics in managed landscapes. Lowresolution habitat classifications may suffice for detecting suitable vole habitats within forest types, but prediction of vole abundance is most accurate at the greatest resolution, i.e., the macrohabitat scale. The utility of forest communities and habitats at various scales to predict vole presence and abundance suggests that C. gapperi may be a useful indicator species for identification and assessment of habitat important for rare small mammal species in the southern Appalachians.

Frequency of movements of small mammals among Atlantic Coastal Forest fragments in Brazil

PIRES, A.S.; LIRA, P.K.; FERNANDEZ, F.A.S.; SCHITTINI, G.M.; OLIVEIRA, L.C. 2002. Frequency of movements of small mammals among Atlantic Coastal Forest fragments in Brazil. Biological Conservation 108:229-237.

Abstract. Rates of interfragment movements were estimated for small mammals inhabiting a group of eight Atlantic Coastal Forest fragments, surrounded by grassland matrix, in order to understand the degree to which each species' population was isolated. Didelphis aurita showed the greatest movement rate (19.4% of recaptures showing interfragment movements), followed by Metachirus nudicaudatus (10.0%), Philander frenata (7.5%), Nectomys squamipes (3.6%), Micoureus demerarae (1.2%) and Akodon cursor (0.25%). Interfragment movements were not detected for Caluromys philander, Oecomys concolor and Oligoryzomys nigripes. Species can be placed along a continuum which goes from species that are represented by a single population in the whole study area, through those with metapopulations, to species that have isolated populations in each fragment. Ability to move among fragments was not related to abundance in the matrix; nevertheless, such ability helps to explain the persistence of species in fragments otherwise too small to support viable populations.

Ecology of a small mammal community in an Atlantic forest area in southeastern Brazil

BERGALLO, H.G. 1994. Ecology of a small mammal community in an Atlantic forest area in southeastern Brazil. Studies on Neotropical Fauna and Environment 29(4):197-217.


Abstract. During a 14 month mark-and-release project in a Atlantic forest area (Jurélia Ecological Station), I studied the population ecology of 8 species of small mammals (3 marsupials and 5 rodents). In a 4,307 trap nights, 182 individuals were captured 650 times. The rodents were caught 73% of the total capture and the marsupials 27%. Oryzomys nitidus was the commonest species in the grid followed by Proechimys iheringi and Metachirus nudicaudatus. The marsupials showed a seasonal pattern of reproduction. As a consequence, the population densities has a peak during the wet months with the antrance of the youngs . The rodents, P. iheringi and O. nitidus bred throughtout the year, althought the former one has a peak in the dry months. Density of O. nitidus was fairly constant, whereas that of P. ihenrigi was higher during the recruitment time. Rodents and marsupials contributed with the same biomass in Juréia small mammal community.

Microtus population biology: demographic changes in fluctuating populations of M. ochrogaster and M. pennsylvanicus in southern Indiana

KREBS, C.J.; KELLER, B.L.; TAMATIN, R.H. 1969. Microtus population biology: demographic changes in fluctuating populations of M. ochrogaster and M. pennsylvanicus in southern Indiana. Ecology 50(4):587-607.

Abstract. Microtus pennsylvanicus and M. ochrogaster are sympatric in southern Indiana grasslands. From June 1965 to August 1967 four populations were live trapped, three of them in 0.8-hectare (2-acre) outdoor pens. Both species increased during 1965 and reached peak densities in summer 1966. Microtus ochrogaster declined abruptly that fall and remained low; M. pennsylanicus declined the following spring.
One of the fenced populations increased to a density about three times that of its unfenced control. By early fall 1966 it had nearly destroyed its food resources and then suffered a severe decline associated with obvious overgrazing and starvation. No such overgrazing has been seen on any unfenced grasslands in this area. Dispersal is probably necessary for normal population regulation in these voles, since fenced populations seem unable to regulate their density below the limit set by starvation.
Both species bred extensively in the winter of 1965-66 during the phase of population increase. There was little or no breeding during the winter after the peak.
Survival of females in the trappable population of both species was high and relatively constant until the end of the cycle. In males, periods of low survival punctuated the increase and peak phases, and these periods of low male survival did not occur at the same time in the two Microtus species. Some mortality processes are thus higly specific for sex and species. In the fenced populations survival rates were very high and no sporadic male losses occurred.
Increasing and peak populations of M. pennsylvanicus and M. ochrogaster are characterized by adults of large body size. During the increase and peak phases some voles stopped growing at low weights (30-40 g) while others reached high aymptotic weights (45-55 g).
The demography of these Microtus species in southern Indiana is similar to that of other cyclic voles and lemmings in temperate and arctic areas.

Mamíferos: da Terra aos Mares

A equipe do Laboratório de Ecologia de Mamíferos da Unisinos têm o prazer de convidar todos a participar da oficina Mamíferos: da Terra aos Mares.

A oficina visa apresentar o grupo dos mamíferos com aspectos de sua evolução, diversidade, ecologia, manejo, conservação e relações com o homem. A oficina ocorrerá nos dias 24 e 25 de agosto, e 1º de setembro de 2012, na Unisinos (Univerdade do Vale do Rio dos Sinos), em São Leopoldo, RS. As inscrições podem ser realizadas diretamente pela internet através do link: http://www.unisinos.br/extensao/eventos/EX120309/EX120309-00001/620/apresentacao.

DATAS: 24 e 25 de agosto, e 1º de setembro de 2012.


INVESTIMENTO: R$ 100,00.


INFORMAÇÕES: www.unisinos.br/eventos (eventos saúde).


CONTEÚDO PROGRAMÁTICO PREVISTO
A oficina será dividida em quatro módulos, sendo o primeiro módulo uma apresentação geral sobre características, diversidade e evolução dos mamíferos. Os quatro módulos seguintes apresentarão aspectos gerais e ecológicos sobre os mamíferos terrestres, e os quatro módulos seguintes apresentarão técnicas de estudo e monitoramento de populações de mamíferos marinhos, bem como suas interações com o homem.


O conteúdo detalhado previsto (sujeito a modificações) segue abaixo:


24/ago/2012
- Introdução geral: mamíferos, da terra aos mares (Msc Paulo T. Sarti, Fernando R.V. Lopes).

25/ago/2012

- Biologia e ecologia de pequenos mamíferos (Msc Maury S.L. Abreu).

- Padrões de microestrutura de pelos: identificando mamíferos (Nathalia S. Freitas).

- Mamíferos terrestres de médio e grande porte (Msc Paulo T. Sarti).

- O uso do habitat por mamíferos terrestres (Guilherme W. Schmitz).

01/set/2012

- Técnicas de estudo em mamíferos-marinhos: coleta, curadoria de coleção e estudos osteológicos (Biol. Ana Paula Costa).

- Técnicas de estudo em mamíferos-marinhos: monitoramento de populações (Biol. Rodrigo Machado, Biol. Ana Paula Costa, Fernando R.V. Lopes).

- Interações entre mamíferos aquáticos e a atividade pesqueira: da pesca cooperativa ao conflito (Biol. Rodrigo Machado).

- Dimensões humanas (Mônica Terra, Biol. Ana Carolina Pont).

Population ecology and reproduction of the white-eared opossum Didelphis albiventris (Mammalia, Marsupialia) in an urban environment of Brazil

CÁCERES, N.C. 2000. Population ecology and reproduction of the white-eared opossum Didelphis albiventris (Mammalia, Marsupialia) in an urban environment of Brazil. Ciência e Cultura Journal of the Brazilian Association for the Advanced of Science 52(3):171-174.

Abstract. The seasonal variation in numbers of individuals, causes for death, breeding season and litter size of the white-eared opossum, Didelphis albiventris, were studied in two small urban forest fragments of southern Brazil. In order to trap opossums, 30 live traps were used once a weak in a forest fragment (5 ha) between February 1995 and January 1996. In addition, 10 traps were used twice a month in another area (2.5 ha) between Novemeber 1996 and February 1997. Individuals trapped were sexed, aged, and released. Females with litter had their pouch young counted. The bait used was banana with codfish liver oil. As results after an effort of 1770 traps set, 37 opossums were captured (20 females and 17 males) with the sex ratio being significantly equal (p > 0.40). Juvenile individuals were captured seasonally during the wet season (spring and summer). Since juveniles represented the most common individuals trapped, total abundances were heigher during the wet season. Immigrations (plus births) rather than emigrations were thought to be the main factor for abundance variations. Moreover, road kill by cars and fights with dogs were the main causes for death of opossums. Based on time of captures of recently weaned opossums and females with litters, the breeding season showed mainly two periods of births (between August and November), though two litters were seen in April of two years. The mean litter size was 9.0 young (N = 14 litters). The white-eared opossum revealed a great potential to colonize urban environments where there are forest fragments, with its higher numbers of juveniles compensating adult deaths mainly by anthropical factors.

Ecology of the water opossum Chironectes minimus in Atlantic forest streams of southeastern Brazil

GALLIEZ, M.; LEITE, M.S.; QUEIROZ, T.L.; FERNANDEZ, F.A.S. 2009. Ecology of the water opossum Chironectes minimus in Atlantic forest streams of southeastern Brazil. Journal of Mammalogy 90(1):93-103.

Abstract. We studied the population structure, spatial patterns, and activity patterns of the water opossum (Chironectes minimus) via capture-mark-recapture and radiotelemetry from October 2004 to October 2006 in Atlantic Forest streams in southeastern Brazil. We tested the hypothesis of reproductive seasonality, the usual pattern in neotropical marsupials, by examining recruitment of juveniles. The hypothesis was rejected, supporting the alternative hypothesis that breeding by water opossums was better explained by its habitat characteristics and prey availability than by its phylogenetic ancestry. The observed sex ratio was significantly biased toward males. The home lengths of individual water opossums varied from 844 to 3,724 m. Males had larger home lengths than females, and there were male-male and male-female overlaps. The longer home lengths for males may explain the observed sex ratio bias, because males are more exposed to capture. All individuals used stream stretches with preserved riparian forest, fast-flowing water, and stony substrate. The hypothesis that activity was homogeneously distributed throughout the night was rejected; activity began right after sunset and ended before sunrise, but with higher levels of activity in the first 6 h of the night. Because of anthropogenic alterations of hydrographic basins, water opossums may be threatened by reduction of their main habitat, streams with fast-flowing water and stony substrate.

Differences in population density and energy use between birds and mammals: a macroecological perspective

SILVA, M.; BROWN, J.H.; DOWNING, J.A. 1997. Differences in population density and energy use between birds and mammals: a macroecological perspective. Journal of Animal Ecology 66(3):327-340.

Abstract.
1. Data from 364 mammal and 564 bird species were used to compare these two taxa in the patterns of variation in population density and energy use as a function of body mass.
2. This study demonstrates previously unappreciated quantitative differences between mammals and birds. Over a wide range of sizes, population densities and rates of energy use are at least one order of magnitude higher in mammals than in birds of similar size. The highest population densities are found in species that weigh about 100 g in mammals and 30 g in birds.
3. Comparisons between mammals and birds from the same dietary category indicate that mammals maintain higher densities and use more energy than birds. Insectivorous mammals and birds maintain the lowest densities.
4. Flying mammals and birds reach lower densities and use more energy than nonflying forms.

5. These findings reveal relationships between the morphology, physiology and behaviour of individual organisms and the ecological performance of these endothermic vertebrates in populations, communities and ecosystems: relationships that have not previously been appreciated.

Evolution of nakedness in Homo sapiens

RANTALA, M.J. 2007. Evolution of nakedness in Homo sapiens. Journal of Zoology 273:1-7.

Abstract. Homo sapiens L. is the only existing primate species lacking in functionally effective thermally insulating fur. As all other primates have considerable hair covering, it has always been accepted that our ancestors must once have had a respectable amount of body hair. Unfortunately, fossils cannot help us when it comes to differences in skin and hair. Recent DNA analysis, however, has given us some idea of when and where the great denudation took place. A number of hypotheses have been proposed to account for this feature, but none of these has gained general acceptance. In this paper, I present these hypotheses in the light of current empirical evidence and discussion.

Where have all the cavies gone? Causes and consequences of predation by minor grison on a wild cavy population

KRAUS, C.; RÖDEL, H.G. 2004. Where have all the cavies gone? Causes and consequences of predation by minor grison on a wild cavy population. Oikos 105:489-500.

Abstract. We investigated whether predation by the minor grison (Galictis cuja , a small mustelid) played a key role in limiting a wild cavy population (Cavia magna), ultimately leading to its local extinction. Radio-telemetry and capture-mark-recapture techniques were used to estimate grison predation rates (kill rates), time-specific probabilities of apparent mortality (population loss rate), overall mortality and grison predation for the cavy population. Additionally, we present data on alternative prey species, grison diet and reproduction to show potential proximate mechanisms of grison predation on wild cavies. The predictions specified were mostly confirmed: (1) grison predation was responsible for almost 80% of the cavies killed by known predators; (2) grison predation probabilities paralleled those of overall mortality of cavies over time; and (3) also those of the apparent mortality of the population. Thus, the population dynamics and the local extinction of the cavy population were not due to emigration processes. (4) Grison predation rates were not density-dependent, but showed pronounced peaks during the austral summer. The grison mainly preyed on small mammals: two water-rat species and the wild cavies. When the availability of alternative prey decreased in summer, the grison appeared to specialise on cavies. The onset of grison reproduction was somewhat delayed in relation to the onset of cavy reproduction. The lack of alternative prey coincided with high grison food demands due to reproduction, leading to a very high predation pressure ultimately resulting in the local extinction of the cavy population. We conclude that grison predation was indeed the main factor driving changes of the cavy population studied and speculate why caviomorph rodents might be especially susceptible to local extinction processes.