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M. Kery

Publications and source records attributed to M. Kery.

22 records · Page 2Linked to original sources
USGS2003

Estimation of ocelot density in the pantanal using capture-recapture analysis of camera-trapping data

Neotropical felids such as the ocelot ( Leopardus pardalis ) are secretive, and it is difficult to estimate their populations using conventional methods such as radiotelemetry or sign surveys. We show that recognition of individual ocelots from camera-trapping photographs is possible, and we use camera-trapping results combined with closed population capture-recapture models to estimate density of ocelots in the Brazilian Pantanal. We estimated the area from which animals were camera trapped at 17.71 km 2 . A model with constant capture probability yielded an estimate of 10 independent ocelots in our study area, which translates to a density of 2.82 independent individuals for every 5 km 2 ( SE 1.00).

Journal of Mammalogy↗
USGS2002

Demographic consequences of inbreeding and outbreeding in Arnica montana: A field experiment

1. The genetic constitution of populations may significantly affect demography. Founder populations or isolated remnants may show inbreeding depression, while established populations can be strongly adapted to the local environment. Gene exchange between populations can lead to better performance if heterozygosity levels are restored (heterosis), or to reduced performance if coadapted gene complexes are disrupted (outbreeding depression). 2. Five populations of the self-incompatible perennial Arnica montana (Asteraceae) were analysed for the demographic consequences of inbreeding and of intra- and interpopulation outcrossing, using both small and large populations as donors for the latter. We analysed seed production and seed weight and monitored growth, survival and flowering of offspring introduced as seeds and as 4-week-old seedlings in a 4-year field experiment. 3. Reduced seed set after selfing was probably due to the self-incompatibility system rather than to inbreeding depression. There was a significant increase for seed set after interpopulation crosses, which resulted from the alleviation of low mate availability in one of the small populations. 4. Significant inbreeding depression was observed for growth rates of plants introduced as seedlings. We found significant heterosis for flowering probability of plants introduced as seeds, but for plants introduced as seedlings, heterosis for seedling size and flowering probability was only marginally significant. Outbreeding depression was not observed. 5. The results of this study are important for reinforcement measures in small, remnant populations. Significant differences among populations for all measured fitness components suggest that reinforcement is best achieved using material from several populations. 6. The observed higher survival of seedlings as compared with seeds suggests that it is better to plant individuals than to sow. Sowing, however, is easier and cheaper, and was more likely to eliminate poorly adapted genotypes before they contribute to the next generation.

Journal of Ecology↗
USGS2002

Inferring the absence of a species: A case study of snakes

Though the presence of a species can be unequivocally confirmed, its absence can only be inferred with a degree of probability. I used a model to calculate the minimum number of unsuccessful visits to a site that are necessary to assume that a species is absent. The model requires the probability of detection of the species per visit to be known. This probability may vary depending on habitat, year, season, the area surveyed, the population size of the species, and the observer. I studied 3 European snake species-asp viper ( Vipera aspis ), smooth snake ( Coronella austriaca ), and grass snake ( Natrix natrix )-over a 5-yr (1994-1998) interval, and made 645 visits to 87 sites during their activity periods. I used a generalized logistic regression approach with random effects for years and sites to (1) estimate the probability of detection of these species from sites known to be occupied, (2) test factors affecting it, and (3) compute the minimum number of times that a site must be visited to infer the absence of the particular species. Probability of detection for all species was heavily influenced by an index of population size. For V. aspis , probability of detection increased from 0.23 to 0.50 and 0.70 in small, medium, and large populations, respectively. Similarly, probability of detection increased from 0.09 to 0.45 and 0.56 in small, medium, and large populations of C. austriaca , respectively, and from 0.11 in small to 0.25 in medium and large populations of N. natrix . Probability of detection also varied across months for all 3 species, among habitat types ( C. austriaca only), and from year to year ( N. natrix only). Sites with unknown occupancy status conservatively may be assumed to be occupied by small populations. I calculated that such sites need to be surveyed 12, 34, and 26 times for V. aspis , C. austriaca , and N. natrix , respectively, before assuming with 95% probability that the site is unoccupied. These results suggest that some species may be more wide-spread than thought. However, to ascertain the presence of such species at a site, search efforts need to be intensive.

Journal of Wildlife Management↗