Paoli, T., Tacconi, G., Borgognini Tarli, S. M. & Palagi, E. 2007: Influence of feeding and short-term crowding on the sexual repertoire of captive bonobos (Pan paniscus). — Ann. Zool. Fennici 44: 81–88.

Socio-sexuality has been described in bonobos as a mechanism reducing social tension. We studied a captive group of bonobos (Apenheul colony) and tested the influence of feeding sessions on various sexual patterns to functionally differentiate them. Non-reproductive sexual interactions (mounting, GG-rubbing) peaked during the feeding period, whereas copulations did not. During short-term crowding, aggression, self-grooming and copulation rates did not change, however, non-reproductive sexuality and grooming intensified. We suggest that during feeding bonobos may selectively use non-reproductive sex to reduce tension, and that during short-term crowding they may employ both grooming and non-procreative sexuality to avoid a potential raise in tension.

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Yang, S., Ruuhola, T. & Rantala, M. J. 2007: Impact of starvation on immune defense and other life history traits of an outbreaking geometrid, Epirrita autumnata: a possible causal trigger for the crash phase of population cycle. — Ann. Zool. Fennici 44: 89–96.

Outbreaking populations of the autumnal moth, Epirrita autumnata, are regularly facing a shortage of food and starvation. We found that starvation led to a prolonged larval development and a marked reduction in pupal weights. A decrease in female pupal weight caused a 50% decrease in the realized fecundity. Due to starvation the melanotic encapsulation rate decreased but the activity of PO — a key enzyme in the melanotic pathway that may indicate scarcity of PO substrates due to starvation — increased. Our results suggested that the shortage of food during high-density years reduce markedly the fecundity of E. autumnata, and may also reduce the ability of the autumnal moth to resist parasitoids and pathogens. Altogether, starvation may potentially destabilize the pathogen dynamics of insects and may be a proximate reason for moth population crashes.

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Loughran, M. F. E. 2007: Social organisation of the male field vole (Microtus agrestis): a case of transient territoriality? — Ann. Zool. Fennici 44: 97–106.

The social organisation of a population of Microtus agrestis was studied by trapping and radiotracking in southern England. There was no significant variation in male home-range size during the breeding season or between years but there was significant variation in core areas between years but not during the breeding season. There was no significant relationship with male density and core area size but there was a significant increase in home range size as density decreased. There were no significant correlations between home-range size and body mass. In both 1995 and 1996, there was an increase in mean exclusivity of core areas that coincided with an increase in nearest neighbour distances as the breeding season progressed suggesting a territorial social system. Male residency was transient and recruitment of female offspring influenced residency.

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Borkowski, J. & Pudelko, M. 2007: Forest habitat use and home-range size in radio-collared fallow deer. — Ann. Zool. Fennici 44: 107–114.

While habitat use by fallow deer has previously been described on the basis of direct observations, this paper presents similar data on radio-collared individuals. Our data show that annual home ranges of males (at 9.75 km2) appeared much larger than those of females (2.1 km2). Thickets and meadows were the most often used habitats, while mature forests and young plantations were least utilised. Diurnal and nocturnal habitat selection patterns differed significantly. The primary difference was the use of meadows, which was higher at night than during the day. Results on the representativeness of diurnal habitat use to 24-hour data were equivocal. Although daytime and 24-hour habitat use patterns were similar, day vs. night and night vs. 24-hour habitat use patterns differed significantly. Our results suggest that when open habitats are involved, the representativeness of daytime data to 24-hour habitat use may be less than complete. This study also indicates that calculations of habitat use by fallow deer based on direct observations are likely to underestimate the use of closed habitats.

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Rintala, J. & Tiainen, J. 2007: Indexing long-term regional bird population dynamics with nestling ringing data. — Ann. Zool. Fennici 44: 115–140.

Finnish nestling ringing data were used to index regional starling Sturnus vulgaris population trends from 1951 to 2001 using log-linear models. A population model with a similar pattern of decline to the actual one was initialised using a resource selection function, which related presence–absence observations of ringed broods to environmental covariates. A data correction was necessary because uncorrected missing counts (indistinguishable in the source data from zero counts) seriously underestimated the population decline. On the basis of the corrected estimate, starlings declined by 80% between the early 1970s and mid-1980s. The decline was greatest in northern Finland. Extinctions were common among local populations during the decline; their frequency increased towards the north, resulting in overall range contraction.

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Wegge, P. & Kastdalen, L. 2007: Pattern and causes of natural mortality of capercaille, Tetrao urogallus, chicks in a fragmented boreal forest. — Ann. Zool. Fennici 44: 141–151.

Over a 3-year period, we equipped 115 newly hatched capercaillie chicks in 29 broods with small radio transmitters in southeast Norway. Besides monitoring the fate of the chicks, we measured the abundance of microtine rodents and insect food and, together with weather records, we examined the observed mortality in relation to these factors. On average, 57% of the chicks died within the first month of life. Mortality was highest during the first 3 weeks, coinciding with the period when chicks feed almost exclusively on insects, depend heavily on their mother for maintaining body warmth, and cannot fly well. Predation was by far the most important proximate cause of mortality, accounting for 90% of all observed losses. Only 7% of the losses could be ascribed to direct effects of cold and wet weather, all recorded during the first 8 days of life. However, because predation losses were also quite high during and immediately after heavy rainfalls, adverse weather probably predisposed the chicks to mammalian predation. Most chicks were killed by mustelids, mainly pine martens; low numbers of red fox due to sarcoptic mange probably explains the low proportion taken by this predator. Among known predation losses (N = 40), goshawks accounted for a minimum of 25%. Chick mortality during the first month varied markedly (29%–83%) among the three years. It was highest in the year when June weather was exceptionally wet and cold; the same year when the density of microtine rodents and food abundance in terms of insect larvae were highest. Net production in late August was poorly related to chick loss during the first month posthatch.

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Reznick, D. & Bryant, M. 2007: Comparative long-term mark-recapture studies of guppies (Poecilia reticulata): differences among high and low predation localities in growth and survival. — Ann. Zool. Fennici 44: 152–160.

Life history theory predicts that high extrinsic mortality rates will cause the evolution of earlier maturity and increased reproductive effort. Guppies that co-occur with predators support these predictions because they attain maturity at an earlier age and have higher levels of reproductive effort than their counterparts from localities that lack predators. In the past, we used short term (12 day) mark-recapture studies to show that guppy populations that co-occur with predators do in fact have higher mortality rates than those that do not. Here we extend this result to long term mark-recapture studies with a single recapture interval of over 200 days. We show that the recapture probabilities after these longer intervals are very similar to what one would predict based on the short term studies. Because of the multiplicative nature of mortality rate, the differences in recapture rates in guppies from low as opposed to high predation sites are now much more dramatic, on the order of 20 to 30 fold after 200+ days, as opposed to being around 15% higher after 12 days. The earlier short-term studies also revealed that guppies from high predation localities grow faster, in part as an indirect effect of predators because they reduce guppy population densities and increase per capita food availability. The long-term studies reported here yield the same result, but the difference between high and low predation localities is again far more dramatic as a consequence of the longer duration of the recapture interval. These observations, in combination with those of the earlier work, support the hypothesis that the increased mortality that accompanies predation represents a plausible mechanism that causes the evolution of the observed differences in life histories; however, the confounding of mortality rate and growth rate also suggests that more complex life history models that include density regulation and eco-evolutionary interactions may provide a better explanation for life history evolution in guppies.

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