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.

BIRD CONTROL METHODS AND DEVICES--COMMENTS OF THE NATIONAL PEST CONTROL ASSOCIATION

It may be useful to review some of the considerations that go into recommendations concerning bird management. Later I will make some comments concerning specific methods and devices being used in or promoted for bird control work regardless of whether or not they are new. Members of the National Pest Control Association provide a variety of services, such as fumigation, termite control and general pest control which includes rodent control. There are eight such categories listed in our roster, but only one member in five provides every service listed. Bird control is a rather recent development and is the newest category of service to be listed in the NPCA roster where it appeared for the first time in 1959. As of September 1, 1966, 45% of our members' offices indicated that they were prepared to offer bird control service. Less than 40% did so in 1964. Why is it that more of our members do not declare themselves as ready to do bird control work? I believe the most common answer you would find is that bird control is not yet sufficiently established that they can provide a service comparable in quality to that which is provided against termites or cockroaches or rats. Our members simply do not want to jeopardize their reputation on methods that are not certain or are too complex. Others recognize the emotional reaction evidenced by much of the population concerning control of birds and do not want to become involved in work that might offend some of their clientele. Still others simply do not agree that birds are their responsibility.

Long-Term Adult Population Fluctuations and Distribution of the Spot, Leiostomus xanthurus, in Mississippi

Adult specimens of the spot. Leiostomus xanthurus, were collected from bayou, Mississippi Sound, and barrier island locations along the Gulf Coast of Mississippi from November 1982 to July 1989. 7he mean total length of all spot sampled in comparable gill net sets was 219 mm (± 14 standard deviation, n=4,338). Ninety-five percent of the spot were collected in the island and sound areas, where the salinity was higher than in the bayous. Catch per unit effort was high at island and sound stations in spring and autumn, with relatively few fish caught during the winter spawning season and summer. The relatively high frequency of spot observed at the island stations in the autumn was probably influenced by spawning migrations, and the high spring values may represent a combination of two abundant year classes. The two greatest yearly collections, in 1983 and 1986, may have been influenced by sampling conditions or by environmental conditions favorable to survival either during those years or earlier when those fish were postlarvae. The smallest yearly catch occurred in 1985 and may have reflected the harsh weather conditions that year.