Kokko, H., Helle, E., Lindström, J., Ranta, E., Sipilä, T. & Courchamp, F. 1999: Backcasting population sizes of ringed and grey seals in the Baltic and Lake Saimaa during the 20th century. — Ann. Zool. Fennici 36: 65–73.
Abstract, Full text (print quality pdf)
Klemola, T., Korpimäki, E., Norrdahl, K., Tanhuanpää, M. & Koivula, M. 1999: Mobility and habitat utilization of small mustelids in relation to cyclically fluctuating prey abundances. — Ann. Zool. Fennici 36: 75–82.
Abstract, Full text (print quality pdf)
Blanco, G., Seoane, J. & de la Puente, J. 1999: Showiness, non-parasitic symbionts, and nutritional condition in a passerine bird. — Ann. Zool. Fennici 36: 83–91.
Abstract, Full text (print quality pdf)
Christiansen, P. 1999: What size were Arctodus simus and Ursus spelaeus (Carnivora: Ursidae)? — Ann. Zool. Fennici 36: 93–102.
Abstract, Full text (print quality pdf)
Niva, T. 1999: Relations between diet, growth, visceral lipid content and yield of the stocked brown trout in three small lakes in northern Finland. — Ann. Zool. Fennici 36: 103–120.
Abstract, Full text (print quality pdf)
Commentaries (abstracts not available)
Brunton, C. F. A., Atkinson, R. J., Ager, M. L. & Majerus, M. E. N. 1999: An observation of directional asymmetry in wing spots of two Arctic butterflies (Colias, Pieridae). — Ann. Zool. Fennici 36: 121–123.
Full text (print quality pdf )
Pöysä, H. & Milonoff, M. 1999: Processes underlying parental care decisions and crèching behaviour: clarification of hypotheses. — Ann. Zool. Fennici 36: 125–128.
Full text (print quality pdf)
Kokko, H., Helle, E., Lindström, J., Ranta, E., Sipilä, T. & Courchamp, F. 1999: Backcasting population sizes of ringed and grey seals in the Baltic and Lake Saimaa during the 20th century. — Ann. Zool. Fennici 36: 65–73.
Baltic Sea populations of the ringed seal (Phoca hispida) and grey seal (Halichoerus grypus) have been dramatically declining throughout this century. They are currently recovering from a population low in the 1970s, but sizes before the decline remain unknown. The land-locked Saimaa ringed seal (Phoca hispida saimensis) has similarly been declining over much of the century. We use past bounty statistics to estimate sizes of these three populations at the beginning of this century, and investigate the sensitivity of our results to assumptions on population growth, density dependence, the true extent of kills, and the age of killed individuals. The possible range extends from 50000 to 450000 individuals for Baltic ringed seals, from 30000 to 200 000 for grey seals, and from only 100 to 1300 individuals for Saimaa seals. The larger estimates apply if hunting tended to remove adult individuals with high reproductive value, and if the initial population was regulated by density dependence rather than kept below its true carrying capacity by nineteenth-century hunting. The low estimate for the Saimaa seal may either indicate that it was initially less abundant than thought, or that known hunting statistics simply do not capture the true magnitude of the decline.
Klemola, T., Korpimäki, E., Norrdahl, K., Tanhuanpää, M. & Koivula, M. 1999: Mobility and habitat utilization of small mustelids in relation to cyclically fluctuating prey abundances. — Ann. Zool. Fennici 36: 75–82.
We examined the winter season mobility and habitat utilization of two mustelid predators, the least weasel (Mustela n. nivalis) and the stoat (M. erminea) in western Finland. Cyclically fluctuating abundances of voles offered an opportunity to compare species-specific behavioral adjustments to the density of main prey. Daily lengths of small mustelid snowtracks in different habitats were recorded during six successive winters covering two three-year population cycles of voles (field vole Microtus agrestis, sibling vole M. rossiaemeridionalis and bank vole Clethrionomys glareolus). Tracks of least weasels were longest in the low phase of the vole cycle indicating that least weasels as Microtus vole specialists increased mobility in searching for prey at low densities of voles. The mobility of stoats was highest in the early decline phase. Both small mustelid species preferred farmland habitats typical for Microtus species, in particular at high densities of voles. Stoats as semi-generalist predators may shift to alternative prey leading to changes in habitat utilization, when voles are decreased to low densities. This was observed when stoats utilized woodland habitats more in the low than in other phases of the vole cycle.
Blanco, G., Seoane, J. & de la Puente, J. 1999: Showiness, non-parasitic symbionts, and nutritional condition in a passerine bird. — Ann. Zool. Fennici 36: 83–91.
The study of host-symbiont interactions has mainly focused on how parasites influence the fitness and behaviour of their host. Two common assumptions of such studies are that all symbiontic organisms are parasites, and that they are directly or indirectly related to host traits which act as signals of quality in mate choice. We assessed the prevalence and abundance of feather mites (Proctophyllodes pinnatus; Astigmata; Protocphyllodidae) on Linnets (Carduelis cannabina; Aves; Carduelinae) and examined how the abundance of mites may be related to the condition and plumage colour of Linnets. Mite prevalence was so high (near 100%) that no variation could be found between age classes or sexes. However, mite abundance was significantly higher in males than in females. No significant relationship was found between mite abundance and host nutritional condition, except for yearling females. Nutritional condition and showiness of secondary sexual traits (carotenoid-based plumage patches) were not correlated in male linnets. Size and brightness of red patches in the plumage of males varied with age, but were unrelated to mite abundance when age was taken into account. The absence of effects of mites is in agreement with the long held, neglected view that feather mites form non-parasitic associations with birds. Higher mite abundance on males may be attributed to more secretions of the uropygial gland, on which mites feed. Gender variation in plumage colour and abundance of feather mites suggests a common hormonal-mediated mechanism regulating both traits.
Christiansen, P. 1999: What size were Arctodus simus and Ursus spelaeus (Carnivora: Ursidae)? — Ann. Zool. Fennici 36: 93–102.
Body masses of the giant short-faced bear (Arctodus simus Cope) and the cave bear (Ursus spelaeus Rosenmüller & Heinroth) were calculated with equations based on a long-bone dimensions:body mass proportion ratio in extant carnivores. Despite its more long-limbed, gracile and felid-like anatomy as compared with large extant ursids, large Arctodus specimens considerably exceeded even the largest extant ursids in mass. Large males weighed around 700–800 kg, and on rare occasions may have approached, or even exceeded one tonne. Ursus spelaeus is comparable in size to the largest extant ursids; large males weighed 400–500 kg, females 225–250 kg. Suggestions that large cave bears could reach weights of one tonne are not supported.
Niva, T. 1999: Relations between diet, growth, visceral lipid content and yield of the stocked brown trout in three small lakes in northern Finland. — Ann. Zool. Fennici 36: 103–120.
Diet, growth, visceral fat accumulation and a consecutive yield of the stocked brown trout (Salmo trutta L.) (four age groups, initial weight range 29–373 g) were studied in three small Finnish lakes in 1991–1996. The average growth rate and visceral lipid content were significantly greater in lakes and years when the trout fed mainly on small fish, such as vendace (Coregonus albula L.), ninespine stickleback (Pungitius pungitius L.) and one-summer-old perch (Perca fluviatilis L.) than their insectivorous conspecifics. The stocked trout initially foraging unpreferred food items shifted rapidly to feed on small fish when their stocks became abundant. Piscivorous trout increased their visceral lipids prior to winter whereas in insectivorous fish these decreased gradually during the growth season which probably caused increased overwinter mortality. Therefore, relative yields were significantly higher for piscivorous than insectivorous trout. On the other hand, the largest trout at release showed the poorest performance irrespective of the quality of the foraging environment.