Dynamics of the Arctic Fox Population on St. Lawrence Island, Bering Sea

English abstract: We hypothesized that the arctic fox, Alopex lagopus (Linnaeus), population on St. Lawrence Island was cyclic and that its fluctuations in size. structure, and productivity were correlated with the relative size of the population of northern voles, Microtus oeconomus Pallas, the primary prey. Based on a nine-year study, we determined that the variations in size of the fox and vole populations were similar, but they both were of low amplitude and not closely correlated. The high pregnancy rate (mean, 86%/yr) and numbers of young conceived (mean, 11.5/pregnancy) did not vary significantly among years, probably because of the consistently abundant and diverse food supply available to the foxes. The age composition of the trappers' catch of foxes each winter also was comparatively stable, but it was closely correlated with the size of the vole population in the previous summer. The survival of the young foxes during the summer probably was dependent on the availability of the voles, The composition of the catch also appeared to be influenced by immigration of faxes from the adjacent continents via the pack ice. French abstract: Nous avons émis I'hypothèse que la population du renard arctique, Alopex lagopus (Linnaeus), sur I'île Saint Lawrence était cyclique el que les fluctuations concernant sa tailIe, sa structure et sa productivité étaient corrélées à la taille relative de la population du campagnol nordique. Microtus oeconomus Pallas, sa principale proie. En nous appuyant sur une étude menée sur neuf ans, nous avons déterminé que les variations dans la taille des populations du renard et du campagnol étaient semblables. mais que toutes deux avaient une faible amplitude et n'étaient pas corrélées de façon étroite. Le taux de grossesse élevé (moyenne 86 p. cent/an) et Ie nombre dc petits conçus (moyenne 11,5/grossesse) ne variaient pas de façon significative au cours des ans, probablement à cause de I'abondance et de la variété de sources de nourriture pour les renards. La composition d'âge des prises des trappeurs était également stable d'un hiver à I'autre, mais elle était corrélée de façon étroite avec la taille de la population dc campagnols au cours de I'été précédent. La survie des renardeaux au cours de I'été dépendait probablement de la disponibilité des campagnols. La composition des prises semblait aussi être influencée par I'immigration des renards venant des terres continentales adjacentes par la voie de la banquise.

The Probe, Issue 174 – March 1997

Outwitting Urban Beaver, by C. E. "Ki" Faulkner, Regional Director, Region 0, NADCA Bear Gets Attention in Southeast Chinese disease Threatens Rabbits Product Announcements: BEAR BE GONE™ -- a device designed to deter bears from foraging in trash cans. Booklet: "Using Guard Animals to Protect Livestock" Abstracts Published at the 3rd Annual Conference of The Wildlife Society: A case study of black bear movements and survival after landfill closure in the central Adirondacks, by Ann M. Russell and S.L. Simek Ecology of coyotes in a sheep ranching environment, by Ben N. Sacks, J.C.C. Neale, M. Jaeger, and D. R. McCullough Design and analysis of carnivore scent-station surveys, by Glen Sargeant, Douglas H. Johnson, and William Berg Public attitudes toward wildlife damage management, by Robert H. Schmidt, M.W. Brunson, andD. Reiter Human dimensions of wildlife contraception, by Robert H. Schmidt and D. E. Mclvor Economic assessment of rabies control efforts in Texas, by Randy M. Smith Methyl salicylate: a naturally occurring avian repellent, by Shirley Wager-Page A brief historical perspective on wildlife contraception research, by Robert J. Warren Wildlife-caused losses to agriculture in 1994, by Alice P. Wywialowski

THE CURRENT STATUS OF PLAGUE IN CALIFORNIA

At the first Vertebrate Pest Control Conference in 1964, I traced the history of plague control in California and outlined a revised approach, based on newer concepts of plague ecology. In our state of relative ignorance, this required a number of unproved assumptions about plague occurrence in California that verged on crystal ball gazing. These were principally that (1) plague persists in relatively resistant rodent species in certain favorable locations, (2) ground squirrels and chipmunks experience periodic epizootics, but are not permanent reservoirs, (3) plague "foci" of the past were merely sites of conspicuous epizootics, they did not necessarily correspond to permanent foci, and could result from epizootic migrations over considerable distances, and (4) a number of assumptions about areas of greatest epizootic potential can be made by analyzing the pattern of recurrent plague outbreaks in the past. Since then the validity of these assumptions has been tested by the largest outbreak of plague since the early 1940's. We believe that the results have proved the crystal ball largely correct, resulting in much more precise and efficient epizootic surveillance and deployment of control measures than in the past. The outbreak was for us an administrative emergency that exceeded the capacities of the State Health Department. We greatly appreciated the vital help and cooperation of other agencies and individuals. The U.S, Public Health Service accepted a heavy burden of laboratory testing through its San Francisco Field Station, and provided emergency field personnel. The contributions of State Department of Agriculture, Bureau of Weed and Vertebrate Pest Control; U.S. Parks, Forest Service and Bureau of Land Management; local health and agriculture department; and State Division of Parks personnel were essential in accomplishing control work, as well as epizootic surveillance.