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The article presents a study which compares the availability of prey and diet to Florida Burrowing Owls in urban and rural areas. The study determined the differences in the owl's ecology in rural and urban areas in the basis of analysis of pellets, insects and arachids which is the frequent food of the species. It cites that this is the first comparison of prey and diet available for owl populations in urban and rural areas.

The extent and geographic patterns of molecular genetic diversity of the largest remaining free-ranging cheetah population were described in a survey of 313 individuals from throughout Namibia. Levels of relatedness, including paternity/maternity (parentage), were assessed across all individuals using 19 polymorphic microsatellite loci, and unrelated cheetahs (n = 89) from 7 regions were genotyped at 38 loci to document broad geographical patterns. There was limited differentiation among regions, evidence that this is a generally panmictic population. Measures of genetic variation were similar among all regions and were comparable with Eastern African cheetah populations. Parentage analyses confirmed several observations based on field studies, including 21 of 23 previously hypothesized family groups, 40 probable parent/offspring pairs, and 8 sibling groups. These results also verified the successful integration and reproduction of several cheetahs following natural dispersal or translocation. Animals within social groups (family groups, male coalitions, or sibling groups) were generally related. Within the main study area, radio-collared female cheetahs were more closely interrelated than similarly compared males, a pattern consistent with greater male dispersal. The long-term maintenance of current patterns of genetic variation in Namibia depends on retaining habitat characteristics that promote natural dispersal and gene flow of cheetahs. [ABSTRACT FROM AUTHOR]

One behavioral tactic that juvenile mammals can use to resolve conflict with adults is the reversion to behaviors of an earlier developmental stage. Therefore, we examined the appearance, body posture, and ontogenetic differences of submissive crouch behavior between juvenile male and female guanacos from birth to 9 months of age in Tortes del Paine National Park, Chile. On average, submissive crouches appeared 73 days after birth, and juvenile males displayed them more frequently than did juvenile females. Juvenile males also displayed more extreme body postures during submissive crouches than did juvenile females. Sex, group size, and season significantly influenced a juvenile's likelihood of displaying a submissive crouch. [ABSTRACT FROM AUTHOR]

Demography and spatial patterns of free-ranging American mink were documented by continuous year-round trapping and radiotracking along 24 km of the River Thames in England, United Kingdom. An estimated average of 7.19 ± 0.58 SE minks per month were present between May 1995 and August 1997. Kit and juvenile paternity was assessed using 7 microsatellite markers and we observed evidence that multiple paternity occurred in this population. Although males maintained territories during most of the year, they sired litters in areas beyond their territory boundaries. We suggest that a male's inability to monopolize paternity, along with a female's ability to continue ovulation after successful matings (i.e., superfetation) explains why males abandon territoriality during the breeding season. We suggest that the main function of a brief delayed implantation of this species may be to enable female mink to retain superfetation, which facilitates the fertilization of ova from different ovulations by different males. This mink model, consisting of disarticulating residency from fatherhood and the possibility of superfetation, may occur more widely among related species and requires a re-evaluation of mustelid sociobiology. [ABSTRACT FROM AUTHOR]

Focuses on a study which investigated the influence of population density and meteorological conditions on birth mass of guanacos in Chile from 1987 to 1996. Factors affecting mass at birth in wild ungulates; Materials and methods; Results of the study.

We investigated patterns of maternal expenditure and its influence on juvenile survival in the polygynous monomorphic guanaco (Lama guanicoe) in southern Chile from 1990 to 1994. Birth weight and growth rate (until age 1) of males and females were similar. Suckling rates of males and females were not significantly different, although mothers of males rejected suckling attempts more often than mothers of females during fall and winter. Mothers with sons terminated suckling boutsin equal proportion as did mothers with daughters. Our estimated level of reproductive effort for guanacos falls within the range of species exhibiting no sex-biased maternal expenditure on offspring. Mean yearly birth weight was negatively correlated with population density. Mean suckling time throughout the year differed among cohorts, as did the mean number of suckling attempts and rejected suckling attempts per hour throughout the year. Juvenile survival was estimated untilage 1. Of the models with five covariates including juvenile sex, birth weight, adult female aggression toward taggers, mean suckling time, and population density, only mean suckling time and population density were significantly related to survival. The risk ratio for mean suckling time indicates that the risk of mortality increases as suckling time increases, whereas the risk ratio for population density indicates that the risk of mortality decreases as population density increases. Under some conditions increasing population density may be correlated with lower offspring birth weight, yet enhanced juvenile survival. This effect on survival was possibly associated with the number of predators on the study area from year to year. [ABSTRACT FROM AUTHOR]