A captive population in crisis: Testing hypotheses for reproductive failure in captive-born southern white rhinoceros females

The captive southern white rhinoceros (Ceratotherium simum simum) population is not self-sustaining. Many founders reproduced, but reproduction among captive-born (F₁) females has been extremely sluggish. Thus the conservation breeding program for this species faces a looming crisis. Using behavioral observations of a large captive population and a questionnaire survey circulated to facilities worldwide, several hypotheses for F₁ female reproductive failure were evaluated. Counter to predictions regarding behavioral deficiency in sociosexual behaviors, F₁ females were at least as proficient as F₀ females for all behavioral measures. Males also showed no sociosexual preferences for F₀ over F₁ females. Results indicate that most reproductive failure occurs post-copulation. The reigning root-cause hypothesis for F₁ female reproductive failure postulates that F₀ females are behaviorally dominant and suppress reproduction in F₁ females. However, no evidence for behavioral dominance was found and F₁ females housed with F₀ females were more likely to reproduce than those housed without F₀ females. Such social facilitation of reproduction is beneficial to F₁ female reproduction, but does not explain differential reproduction between F₁ and F₀ females. Because the design controlled for current conditions, these results point to development in captivity as the root cause of postcopulatory reproductive failure in F₁ females.     

Effects of rainforest fragmentation on non-flying mammals of the Eastern Dorrigo Plateau, Australia

This paper describes the non-flying mammals recorded in warm-temperate rainforest fragments on the Eastern Dorrigo Plateau of New South Wales, Australia, and investigates the importance of landscape and habitat factors in determining their richness and abundance. Thirty-three rainforest fragments, ranging in size from 0.15 to 996 ha, and five sites within continuous rainforest, were surveyed. Mammal species were detected by live-trapping, spotlighting, diurnal transect walks and nest boxes. Vegetation surveys were carried out within fragments, and landscape parameters such as area and disturbance were measured on-site, via aerial photographs, and through discussion with land-owners. Nineteen species of non-flying mammals were recorded, the most common being two possums (Trichosurus vulpecula, Pseudocheirus peregrinus), a peramelid (Perameles nasuta), two native (Melomys cervinipes, Rattus fuscipes) and one introduced (Rattus rattus) species of rodent and a dasyurid (Antechinus stuartii). Mammal species richness overall was linked overwhelmingly with landscape parameters, particularly fragment area. Analyses of abundance were carried out on small mammal species only. The most important variables for A. stuartii were related to habitat, in particular structures used for nesting. Rattus fuscipes and M. cervinipes were restricted largely to fragments above 1 ha in area, and exhibited complex relationships with several habitat variables. Larger species of mammals were lost progressively from small fragments probably because their spatial requirements could not be met. Protection of existing remnants and establishment of links between these remnants and continuous forest may slow attrition of the region's mammalian fauna.     

Equine neural angiostrongylosis

Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae.     

Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.     

Testosterone serum profile,semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment

This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20‐min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00 hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (p > .05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males.     

Immotile Short‐Tail Sperm Defect in Nelore (Bos taurus indicus) Breed Bulls

This case study reported the presence of short tail sperm defect in the semen of three Nelore breed bulls. The sperm presented 0% of motility in the three animals evaluated and a total of 70%, 61% and 34% of pathologies of the intermediate piece of the tail respectively for animals 1, 2 and 3. It was identified that animals 2 and 3 had high degree of inbreeding, although no relationship was found with animal 1. Animal 2 was the only one that presented inbreeding coefficient (6.25%). His half‐sib (animal 3) and animal 1, from the same herd, had shown no inbreeding, showing that inheritance is not the only determinant factor for its incidence on Nelore males.