Geology topics

M.K. Oli

Publications and source records attributed to M.K. Oli.

3 recordsLinked to original sources

USGS2010

Factors influencing reproductive performance of northern bobwhite in South Florida

Reproductive success is a critical component of individual fitness, and also an important determinant of growth rates of populations characterized by early maturity and high fecundity. We used radiotelemetry data collected during 2003–2008 to estimate reproductive parameters in a declining northern bobwhite ( Colinus virginianus ) population in South Florida, and to test hypotheses regarding factors influencing these parameters. The overall clutch size was 12.10 ± 0.22, but females laid more eggs in their first clutch (12.43 ± 0.24) than in subsequent clutches (10.19 ± 0.53) within a nesting season. Daily nest survival was higher for first (0.966 ± 0.003) than subsequent nests (0.936 ± 0.011). Hatchability (proportion of laid eggs that hatched conditional upon nest survival to hatching) was 0.853 ± 0.008, but was higher for nests incubated by females (0.873 ± 0.009) than those incubated by males (0.798 ± 0.018). The proportion of individuals attempting a second nest was 0.112 ± 0.024 and 0.281 ± 0.040 when the first nest was successful and failed, respectively. Hatchability was lower when the nesting habitat was burned the previous winter. We found no evidence that food strip density (a management practice to provide supplemental food) influenced any of the reproductive parameters. Mean summer temperature affected hatchability, nest survival, and proportion of nests incubated by males. Overall, the reproductive output in our study population was lower than that reported for most other bobwhite populations, indicating that low reproductive performance may have contributed to bobwhite population declines in our study site. These results suggest that current management practices, particularly those related to habitat and harvest management, need careful evaluation.

Florida↗

USGS2010

Patterns of space and habitat use by northern bobwhites in south Florida, USA

The manner by which animals use space and select resources can have important management consequences. We studied patterns of habitat selection by northern bobwhites ( Colinus virginianus ) on Babcock-Webb Wildlife Management Area, Charlotte County, Florida and evaluated factors influencing the sizes of their home ranges. A total of 1,245 radio-tagged bobwhites were monitored for 19,467 radio days during 2002–2007. The mean ( ± 1 SE) annual home range size, estimated using the Kernel density method, was 88.43 ( ± 6.16) ha and did not differ between genders. Winter home ranges of bobwhites (69.27 ± 4.92 ha) were generally larger than summer home ranges (53.90 ± 4.93 ha). Annual and winter home ranges were smaller for bobwhites whose ranges contained food plots compared to those that did not; however, the presence of food plots did not influence summer home ranges. We used distance-based methods to investigate habitat selection by bobwhites at two scales: selection of home ranges within the study site (second-order selection) and selection of habitats within home ranges (third-order selection). Across both scales, bobwhites generally preferred food plots and dry prairie habitat and avoided wet prairies and roads. This pattern was generally consistent between genders and across years. Our data indicate that management practices aimed at increasing and maintaining a matrix of food plots and dry prairie habitat would provide the most favorable environment for bobwhites.

Florida↗

USGS2008

Relative importance of natural disturbances and habitat degradation on snail kite population dynamics

Natural disturbances and habitat degradation are major factors influencing the dynamics and persistence of many wildlife populations, yet few large-scale studies have explored the relative influence of these factors on the dynamics and persistence of animal populations. We used longterm demographic data and matrix population models to examine the potential effects of habitat degradation and natural disturbances on the dynamics of the endangered snail kite Rostrhamus sociabilis in Florida, USA. We found that estimates of stochastic population growth rate were low (0.90). Population growth rate (??) during the first half or our study period (1992 to 1998) was substantially greater than during the second half (1999 to 2005). These 2 periods were characterized by contrasting hydrological conditions. Although ?? was most sensitive to changes in adult survival, the analysis of life table response experiments revealed that a reduction in fertility of kites accounted for >80% of the observed decline in population growth rate. We examined the possibility that the reduction in ?? was caused by (1) habitat degradation due to management, (2) an increase in frequency of moderate drying events in recent years, and (3) both habitat degradation and an increase in frequency of moderate drying events. Our results suggest that both factors could potentially contribute to a large decrease in population growth rate. Our study highlights the importance of simultaneously considering short- and long-term effects of disturbances when modeling population dynamics. Indeed, focusing exclusively on one type of effect may be misleading to both our understanding of the ecological dynamics of the system and to management. The relevance of our results to management is heightened because the snail kite has been selected as a key performance measure of one of the most ambitious ecosystem restoration projects ever undertaken. ?? Inter-Research 2008.

Endangered Species Research↗