Band 68, Heft 2-3

Variations in mammal population sizes can be related to the availability and abundance of their resources. This study reports the population dynamics of four didelphid marsupials ( Didelphis aurita, Philander frenatus, Marmosops incanus and Metachirus nudicaudatus ) and its relation to litter fall, used as a measure of resource production. A capture-mark-recapture study (CMR) was carried out in a disturbed area of the Atlantic forest in Rio de Janeiro State, Brazil, in three grids in the locality of Garrafão from April 1997 to February 1999, every other month. Litter was collected every month using 15 squared litter traps of 0.25 m 2 in the grids (5 in each grid). Leaves, twigs, reproductive structures and total litter fall rates were calculated as tons ha –1 month –1 . Population densities, survivorship and recruitment rates were estimated. For D. aurita and P. frenata , population densities were correlated positively only with litter production. For M. incanus , population density was correlated positively with survivorship, litter production and negatively with rainfall. M. nudicaudatus population density was correlated only with recruitment and twigs abundance. The availability of fruits and arthropods had a large influence in the proximal causes on the variation of small mammal populations. In forests where there is an adequate rate of decomposition of the litter, we may understand how resources influence population variation, and litter becomes the base of resources for such marsupials in the Atlantic forest.

The main purpose of this study was to determine whether the maximum distance traveled and home range area of Nectomys squamipes and Oryzomys russatus differ between sexes, breeding seasons and species. We also evaluated whether rainfall and food availability influenced the maximum distance traveled. Rats were trapped monthly from February 1993 to January 1995 in an area of Atlantic forest, Brasil. Maximum distance traveled by N. squamipes was not related to mass and was longer during the breeding season for males. There were no differences between seasons in the distances traveled by O. russatus , but larger males traveled further. Food availability and rainfall had no effect on the distance traveled by each species. Home ranges of male N. squamipes were larger than those of females during the breeding season, but home ranges did not differ between the sexes in O. russatus . Differences between the two species in movement may be related to differences in mating systems, which are probably promiscuous in N. squamipes and monogamous in O. russatus .

This paper describes the weight variation and reproductive seasonal patterns of the wood mouse in a Mediterranean scrubland in southern Portugal. A total of 156 individuals were marked and followed up to 242 days. Summer corresponded to the non-breeding period in the study area, instead of winter, such as in other areas of central and northern Europe. As a consequence, a displacement of the annual density and weight cycles were observed. The higher densities, usually recorded before the non-reproductive period, were recorded during spring instead of summer. In addition, the typical weight depression of the non-reproductive period was reported in summer. Reproductive individuals were consistently heavier than non-reproductive, except in summer when a significant weight decrease was observed and in autumn when there were few subadults in the population. Juvenile males grew faster than juvenile females. However, there was little evidence of differences on growth of juveniles born at different times of the year.

Gaur ( Bos gaurus ) and banteng ( Bos javanicus ) populations throughout South-east Asia have declined severely because of hunting and habitat fragmentation. Important remnant populations persist in Xe Pian national protected area in southern Lao P.D.R., where sign-based surveys were carried out between 1996 and 1998 to determine their distribution, abundance, and patterns of habitat use. Xe Pian is comprised of a largely intact lowland mosaic of semi-evergreen, mixed deciduous, and dry dipterocarp forest types. Gaur used a broader diversity of these habitat types than banteng, attaining moderate densities in homogeneous semi-evergreen forest as well as expanses of deciduous dipterocarp and mixed deciduous forests. Mixed deciduous forest was the least abundant forest type but was commonly used by gaur. Banteng showed a strong affiliation with drier and more open habitats, especially dry dipterocarp forest, despite increased vulnerability to hunting in these areas in the past. Banteng were not found within large expanses of semi-evergreen forest. Their distribution within Xe Pian was therefore more restricted than gaur, though they were relatively more numerous within two isolated corners of the protected area. Signs of calves and juveniles indicated that both species retained breeding populations in Xe Pian. Remaining herds were small – composed of two to five individuals – but bamboo understories in semi-evergreen forest were a food source that attracted larger congregations of gaur in the rainy season. The banteng population in Xe Pian is globally significant for conservation, while that of gaur is nationally significant. The existence of extensive high quality habitat and on-going collaboration of local people lends hope that Xe Pian's wild cattle will increase, given protection from hunting.

This study describes the diet of European mink ( Mustela lutreola ) in Northern Spain. The diet was analysed from 105 European mink samples. Moreover, we collected other 37 faeces from a radiotracked European mink male. The European mink diet was based on small mammals (relative frequency of occurrences 36,9%), fish (30,6%) and birds (17,8%). The Levins index of trophic-niche width was 3,76. Wood mouse Apodemus sylvaticus was the most consumed small mammal and Cyprinids -mainly Barbus sp . was the most consumed fish. The average size and weight of consumed fish were 13,5 cm and 31,5 g, respectively and males consumed larger and heavier fish than females.

This note details the murid specimens collected in 1997, 1998 and 1999 as the result of surveys of 3 sites in Xe Piane and of 11 sites in Khammouan Limestone NBCA, Lao PDR. Cranial and mandibular remains were obtained from raptor pellets collected from caves, hunters and carnivore droppings. Remains of 287 individuals of 13 species of Muridae were identified; three species from Xe Piane NBCA and 13 species from Khammouan Limestone NBCA. Two species Mus shortridgei and Rattus argentiventer had not previously been recorded from Lao PDR. Remains attributable to two additional genera were also found.

This study examined the development of the tusks and associated skeletal structures in a series of 18 specimens of Sowerby’s beaked whale ( Mesoplodon bidens ) from Scotland. The relative position of the tusks along the length of the mandible was found to move from 23% of mandible length from the anterior extremity in the smallest animal to around 37% in adults, due to a lengthening of the symphyseal region. A previously undescribed sexual dimorphism was noted, a bony abutment, or ossicular dental support, situated directly posterior to the erupted tusks of adult males. Ontogenetic changes associated with male maturity include an increase in tusk length, an increase in the length of the alveolus, a high level of wear on tusks, an increase in the depth of the mandible posterior to the alveolus, an increased level of mesorostral ossification and an overall thickening of the rostrum and the symphyseal region of the mandible. The tusks are presumed to be used in intraspecific aggressive interactions and the ossicular dental support may counteract backward and outward forces on them as they cut through an opponents flesh, while the thickening of the rostrum and mandible may reduce the risk of damage when the two animals make contact.

Three morphological datasets (traditional measurements, dorsal and ventral skull shape coordinates) were used to examine craniometric variation in the water rat Dasymys , a genus found throughout sub-Saharan Africa. This study is the first to examine the entire genus as well as to statistically compare taxa within the genus to the nominate species D. incomtus . Morphological data confirmed that the five species recognised by Musser & Carleton (1993); D. incomtus, D. foxi, D. nudipes, D. montanus and D. rufulus , represent valid morphological species although two of the species do not encompass the geographic areas presently assigned to them. Dasymys rufulus occupies a larger range and D. incomtus a much smaller range than previously suggested with D. rufulus appearing to be part of a species complex. Furthermore, we discerned six additional morphological species resulting from the elevation of four subspecies ( D. i. capensis, D. i. griseifrons, D. i. medius and D. i. longipilosus ) and the recognition of two new species: D. shortridgei (restricted to the Okavango Delta) and D. robertsii (occurring in the Limpopo and Mpumalanga Provinces of South Africa).