Geology topics

Solange Brault

Publications and source records attributed to Solange Brault.

2 recordsLinked to original sources

USGS2006

Albatross populations in peril: A population trajectory for Black-browed Albatrosses at South Georgia

Simulation modeling was used to reconstruct Black-browed Albatross ( Diomedea melanophris ) population trends. Close approximations to observed data were accomplished by annually varying survival rates, reproductive success, and probabilities of returning to breed given success in previous years. The temporal shift in annual values coincided with the start of longline fishing at South Georgia and potential changes in krill abundance. We used 23 years of demographic data from long-term studies of a breeding colony of this species at Bird Island, South Georgia, to validate our model. When we used annual parameter estimates for survival, reproductive success, and probabilities of returning to breed given success in previous years, our model trajectory closely followed the observed changes in breeding population size over time. Population growth rate was below replacement (lambda < 1) in most years and was most sensitive to changes in adult survival. This supports the recent IUCN uplisting of this species from “Vulnerable” to “Endangered.” Comparison of pre-1988 and post-1988 demography (before and after the inception of a longline fishery in the breeding area) reveals a decrease in lambda from 0.963 to 0.910. A life table response experiment (LTRE) showed that this decline in lambda was caused mostly by declines in survival of adults. If 1988–1998 demographic rates are maintained, the model predicts a 98% chance of a population of fewer than 25 pairs within 78 years. For this population to recover to a status under which it could be “delisted,” a 10% increase in survival of all age classes would be needed.

Ecological Applications↗

USGS1994

The status of sea ducks in the North Pacific Rim: Toward their conservation and management

Sea ducks (tribe Mergini after Johnsgard 1960) are the most northerly distributed ducks, and species diversity is greatest in the North Pacific. They exploit a diversity of inshore and offshore marine habitats during the non-breeding season, and their use of habitat during breeding varies from coastal through freshwater wetlands of the tundra and taiga (Figure 1, Appendix 1). Non-breeding cohorts frequent marine habitats most of the year. Sea ducks thus are important indicators of the quality of freshwater and marine ecosystems of northern biomes. Of the 17 species discussed in this manuscript, at least 3 are reported to be declining (Appendix 2). However, the basis for many of those assessments is equivocal because there has been little effort to monitor populations. The efforts to more precisely assess their status point to catastrophic declines (Kertell 1991, Stehn et a 1993). Conservation problems related to sea ducks have a long history throughout the Holarctic. For example, the Labrador duck ( Camptorhynchus labradorius ) became extinct in 1875. (Phillips 1925); common eiders ( Somateria mollissima ) declined seriously throughout the northern hemisphere (Townsend 1914, Phillips 1925, Doughty 1979); harlequin ducks ( Histrionicus histrionicus ) experienced declines in Iceland and Greenland (Gudmundsson1971, Salomonson 1950), and more recently have been designated endangered in eastern Canada (Committee On the Status of Endangered Wildlife in Canada 1990). In Russia, all species of eider and harlequin ducks have been closed to sport hunting since 1981, and the Chinese mergansers ( Mergus squamatus ) presently are extremely rare and fully protected, i.e. category one of the red book (Solomonov 1987).

Transactions of the North American Wildlife and Na↗