Peary Caribou and Muskoxen on Banks Island

Peary caribou and muskoxen were surveyed on Banks Island north of 73° N. in June 1970 to identify critical spring ranges of these animals. The data gathered also lend themselves to population estimations. Critical spring ranges of both animals north of 73° N. are more or less mutually exclusive. Muskoxen were restricted to the eastern side of the island; caribou were widely dispersed and associated with simpler plant communities. Group and herd structures for both animals are given and indicate high productivity. Conservative population estimates indicate far more animals than previously supposed: 5,300-8,000 caribou and 1,200-1,300 muskoxen

Critical temperatures for survival of brood and adult workers of the giant honeybee, Apis dorsata (Hymenoptera: Apidae).

Capped brood ( capped within 36 h) and adult workers of Apis dorsata were removed from naturally occurring colonies and kept incubated in laboratory hoarding cages at constant temperatures ranging from 26 to 45 °C to study mortality, survivorship, and water and syrup consumption. Capped brood died at temperatures above 36 °C. Below 30 °C adults tended to emerge deformed. Low temperatures delayed development. The optimal temperature for complete emergence of healthy adult workers was 34 °C. Adult workers survived well from about 26 to 36 °C. At 38 °C they died within 5 days and at 45 °C they died within 48 hours. Although syrup (1 sugar: 1 water W/W) consumption did not change over the range of temperatures used, water consumption rose rapidly above 38 °C to over 3 ml/bee in 48 hours at 45 °C. Nest temperature control is critical for survival of brood of A. dorsata and adult worker bees have tight constraints on their abilities to endure high temperatures. Water availability is vital for cooling the colony under hot, tropical conditions, and rearing healthy brood

Pollination and Breeding System of Lowbush Blueberries, Vaccinium angustifolium Ait. and V. myrtilloides Michx. (Ericacaeae), in the Boreal Forest

Breeding systems and pollination requirements of two wild lowbush blueberries, Vaccinium angustifolium and V. myrtilloides, in the Canadian boreal forest in the Chapleau Crown Game Preserve, Ontario, were tested. Fruit production, size and seediness were significantly higher in samples exposed to natural pollination than in those cross- or self-pollinated by hand. There were no significant differences among artificial treatments (variously hand-pollinated and bagged) except when cross-pollination (xenogamy) was done by insect pins. In V. angustifolium, the density of flowering varied with forest age (canopy closure). It was most in open areas and least in the sites with the most mature forest. Although fruit-set and seediness varied among forest habitats of different ages, there were no significant differences between sites in forests of different ages. Thus, pollination seems to be similarly effective no matter the age of the forest. In both species, fruit-set in 1992, which had severe June frosts, was markedly poorer than that in 1993 when the flowers suffered little frost damage. The combined number of complete and incomplete seeds from the fruit among the breeding and pollination systems tested were similar; however, the ratio of complete seeds to total seeds was greater from cross-pollinated than from self-pollinated flowers. Our observations indicate that there is little natural fruit-set without insect-mediated cross-pollination and that cross-pollination provides much better fruit and seed-set than does self-pollination

Effects of Forest Cover on Fruit Set in the Woodland Herb, Maianthemum canadense (Liliaceae)

Animal pollination has been recognized as an essential ecosystem function that is potentially under various environmental stresses. We investigated the landscape effects of forest cover at multiple spatial scales on the sexual reproductive success of a common woodland herb in North America, Maianthemum canadense. This species is a self-incompatible species and pollinated by insects requiring natural landscapes. Nine populations were selected in deciduous forests within agricultural fields of southern Ontario, Canada. We investigated whether fruiting success decreases as forest cover surrounding the plant populations increases at the landscape scale. Forest cover was quantified by the proportion of forest within six different radii from 250 to 1500 m. Analyses showed relationships with the proportion of forest at 750- and 1000-m radii and fruiting success in populations of M. canadense. These findings suggest potential local extirpation of M. canadense and indicate that forest loss can negatively impact on even some common woodland herbs

Soil Nutrients and Vegetation Characteristics of a Dorset/Thule Site in the Canadian Arctic

We conducted a systematic study of soils and vegetation present at Arnaqquaksaat on Igloolik Island, Nunavut, a site occupied by Dorset and Thule people prior to 1823 and probably for over a thousand years. We compared this site to an area affected by ongoing mammal and bird activity and an area of relatively unfertilized polar semidesert. At these locations, we estimated percent cover of vegetation, identified vascular plant species, measured soil depth, and collected soil samples. The soil samples were analyzed for total nitrogen, sodium bicarbonate-extractable phosphorus, available potassium, available magnesium, and pH.Percent plant cover, abundance of plant species indicative of enrichment, and soil depth were greatest within the area of anthropogenic influence and decreased downslope to the sea. Total nitrogen level in the upslope area of anthropogenic influence (2.61% ±0.88) was similar to that in areas of bird and mammal activity (2.54% ±0.78); it was higher than the levels in the downslope area of human fertilization (0.65% ±0.82) and the unaltered polar semidesert area (0.28% ±0.38). Phosphorus levels in the influenced areas were 5 to 6 times those in the uninfluenced polar semidesert. The magnesium level was highest in the area of bird and mammal activity (766.8 mg/L ±53.35), whereas potassium levels were similar throughout the study area. The lowest pH was found in the upslope area of past human occupation, and pH differences among sites paralleled those observed for nitrogen.On a effectué une étude systématique des sols et de la végétation présents à Arnaqquaksaat dans l'île Igloolik au Nunavut, un site occupé par les peuples de Dorset et de Thulé avant 1823 et probablement durant plus de mille ans. On a comparé ce site à une zone affectée par l'activité continue de mammifères et d'oiseaux et à une zone de semi-désert polaire relativement non fertilisé. À ces endroits, on a évalué le pourcentage de couvert végétal, identifié les espèces de plantes vasculaires, mesuré la profondeur du sol et prélevé des échantillons de sol. On a analysé ces derniers pour en évaluer la teneur en azote total, phosphore extractible par le bicarbonate de soude, potassium disponible, magnésium disponible et le pH. On a trouvé que le pourcentage de couvert végétal, l'abondance d'espèces végétales révélatrice d'un enrichissement et la profondeur du sol étaient les plus importants à l'intérieur de la zone qui avait subi une influence anthropique et qu'ils décroissaient en descendant vers la mer. Le niveau d'azote total dans la zone supérieure de la pente, qui avait subi une influence anthropique (2,61 p. cent ± 0,88), était semblable à celui des zones où s'exerçait l'activité des oiseaux et des mammifères (2,54 p. cent ± 0,78); il était supérieur aux niveaux trouvés dans la partie inférieure qui avait connu une fertilisation humaine (0,65 p. cent ± 0,82) et dans la zone polaire semi-désertique non altérée (0,28 ± 0,38). Les niveaux de phosphore dans les zones ayant subi une influence étaient de 5 à 6 fois ceux des zones semi-désertiques polaires n'ayant pas subi d'influence. Le niveau de magnésium était le plus haut dans la zone où s'exerçait l'activité des oiseaux et des mammifères (766,8 mg/L ± 53,35), alors que les niveaux de potassium étaient semblables dans toute la zone d'étude. Le pH le plus bas se trouvait dans la zone supérieure de l'endroit ayant jadis été occupé par l'être humain, et les différences dans le pH parmi les sites s'alignaient sur celles observées pour l'azote

Subarctic Records and Range Extensions of Two Species of Tiger Beetles (Coleoptera: Cicindelidae) in Churchill and Wapusk National Park, Manitoba

Two species of tiger beetle (Coleoptera: Cicindelidae) were collected in the vicinity of Churchill, Manitoba and Wapusk National Park. Habitats were dry, sandy areas typically preferred by this family. No tiger beetle has been recorded from this region previously. Cicindela longilabris longilabris was collected in two localities, one south of Churchill and another on a relict beach ridge in Wapusk National Park. Cicindela limbata hyperborea was collected only on the beach ridge, where adults co-occurred with C. longilabris longilabris. These localities represent significant range extensions for both species. Erratum included