Pétillon, J., Lasne, E., Lambeets, K., Canard, A., Vernon, P. & Ysnel, F. 2010: How do alterations in habitat structure by an invasive grass affect salt-marsh resident spiders? — Ann. Zool. Fennici 47: 79–89.
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Karell, P., Lehtosalo, N., Pietiäinen, H. & Brommer, J. E. 2010: Ural owl predation on field voles and bank voles by size, sex and reproductive state. — Ann. Zool. Fennici 47: 90–98.
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Gibb, H. & Johansson, T. 2010: Forest succession and harvesting of hemipteran honeydew by boreal ants. — Ann. Zool. Fennici 47: 99–110.
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Salo, P., Toivola, M., Nordström, M. & Korpimäki, E. 2010: Effects of home-range characteristics on the diet composition of female American mink in the Baltic Sea archipelago. — Ann. Zool. Fennici 47: 111–122.
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Pichorim, M. & Monteiro-Filho, E. L. A. 2010: Population size, survival, longevity, and movements of the biscutate swift in southern Brazil. — Ann. Zool. Fennici 47: 123–132.
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Rossi, V., Piotti, A., Geiger, W., Benassi, G. & Menozzi, P. 2010: Genetic structure of Austrian and Italian populations of Limnocythere inopinata (Crustacea, Ostracoda): a potential case of post-glacial parthenogenetic invader? — Ann. Zool. Fennici 47: 133–143.
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Mitrus, C., Mitrus, J. & Sikora, M. 2010: Sex differences in the rate of food provisioning to nestlings red-breasted flycatchers (Ficedula parva). — Ann. Zool. Fennici 47: 144–148.
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Vakirtzis, A. & Roberts, S. C. 2010: Mate quality bias: Sex differences in humans. — Ann. Zool. Fennici 47: 149–157.
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Pétillon, J., Lasne, E., Lambeets, K., Canard, A., Vernon, P. & Ysnel, F. 2010: How do alterations in habitat structure by an invasive grass affect salt-marsh resident spiders? — Ann. Zool. Fennici 47: 79–89.
In European salt marshes, recent invasions by the grass Elymus athericus raise questions regarding subsequent habitat modification and its effects on the resident biota. In this study, we studied the effects of modified salt-marsh structure on occurring spider assemblages, especially on salt exposure and flood resistance. We showed that locations having tall and deep-rooted invasive vegetation contained more species able to resist tidal floods as compared with locations with natural vegetation. Dominant species displayed different temporal trends between habitat types after flooding, with some species being less affected by floods either in invaded or in natural habitats. Some cursorial species were able to (re)colonize salt marshes after a spring flood as salinity levels decreased. Finally, stand characteristics of E. athericus did not affect the distribution of halotolerant spiders. As a habitat structure relates to flood resistance and/or risk-avoiding strategies, our results indicate that the status of salt-marsh resident species should be considered according to their habitat affinity.
Karell, P., Lehtosalo, N., Pietiäinen, H. & Brommer, J. E. 2010: Ural owl predation on field voles and bank voles by size, sex and reproductive state. — Ann. Zool. Fennici 47: 90–98.
Predation on selected individuals from a population may have consequences for the prey population. We studied predation of breeding Ural owls (Strix uralensis) in southern Finland on their two main prey species, field voles (Microtus agrestis) and bank voles (Myodes glareolus), which fluctuate in abundance between years. We identified sex, body mass and reproductive state of the voles in Ural owl nests and of voles caught by snap-trapping in the study area. Our results showed that Ural owls preyed proportionally more upon reproductively active field voles than expected, whereas no such bias was found for predation on bank voles. There was no difference in sex ratio between preyed upon and trapped field voles or bank voles. Ural owls captured heavier individuals of both field voles and bank voles than expected, and in field voles, but not bank voles, reproductively active individuals were heavier than reproductively inactive individuals. We discuss how differences in social organisation, dispersal and reproductive behaviour may differently affect predation vulnerability of field voles and bank voles. In contrast to the pattern documented in other owl species, we find that Ural owls select larger and reproductively active voles, and may thereby exert a higher population-dynamical impact on vole populations than expected solely from the numbers of voles preyed upon.
Gibb, H. & Johansson, T. 2010: Forest succession and harvesting of hemipteran honeydew by boreal ants. — Ann. Zool. Fennici 47: 99–110.
Ants are important harvesters of plant-derived sugars, but little is known about how anthropogenic disturbances influence this behaviour. We investigated factors related to honeydew harvesting by red wood ants, Formica aquilonia, in managed boreal forests. Ant activity was lowest in middle-age stands (30–40 years old), which had the fewest and smallest ant mounds. It was best predicted by a model containing an interaction among tree species, basal diameter and stand age. Individual workers collected similar masses of honeydew from the different aged stands, which suggests that colonies optimise foraging efforts by adjusting the number of active foragers to match resource availability. The rate of honeydew harvesting from recently clear-cut stands during the survey was similar to that in old stands, although significantly faster than in middle-aged stands. This may be a result of high aphid loads on clear-cuts and recent changes in forest management that improve the temporal continuity of forests for red wood ants. Anthropogenic alteration of habitats thus significantly alters energy use by ants, mainly as a result of changes in the abundance and size of ant colonies. This change is likely to have further consequences for ant-driven ecosystem functions.
Salo, P., Toivola, M., Nordström, M. & Korpimäki, E. 2010: Effects of home-range characteristics on the diet composition of female American mink in the Baltic Sea archipelago. — Ann. Zool. Fennici 47: 111–122.
Predator home-range size may serve as a proxy of resource abundance and spatial structure of home range may also reveal information about diet composition of predators. We studied the diet of American mink Mustela vison, an introduced predator in Europe, to explore diet composition and to examine the association of diet with home-range characteristics. We collected scats of radio-tracked mink (two males and nine females) in summers 2004–2005 in the Archipelago Sea, SW Finland. The most important prey groups were fish (33% occurrence), birds (28%) and small mammals (mainly voles; 15%). The proportion of small mammals in female mink diet correlated positively with home-range size, which indicates that larger home ranges include larger islands, where vole populations are more persistent. Our results highlight the importance of fish as main prey for survival and invasion of mink in the outer archipelago, subsidising mink impact on other prey.
Pichorim, M. & Monteiro-Filho, E. L. A. 2010: Population size, survival, longevity, and movements of the biscutate swift in southern Brazil. — Ann. Zool. Fennici 47: 123–132.
We provide information on population parameters in colonies of the biscutate swift from southern Brazil using the capture–recapture technique. We captured 1020 adults, 233 nestlings and 25 subadults, totaling 1278 marked birds. Models with capture probabilities varying with time and individual animal (CAPTURE program), and with constant survival and time-dependent recapture (MARK program) best fit the data. The results of both methods were relatively similar because the models selected suggested that mortality, recruitment or movement events were unimportant. Population sizes were estimated to be between 187 and 1902 individuals in the four colonies studied. The estimated mean annual survival for the species was 0.88, a value corresponding to an average longevity of 18 years. Little individual movement occurred among the colonies; the largest displacement observed was 120 km. One of the colonies did not display the same capture pattern as that of the others, probably due to space conflicts or shelter occupation time. Our data show that in southern Brazil biscutate swifts do not migrate, possibly because food availability is more constant throughout the year than in other regions (southeast and northeast) where migration occurs.
Rossi, V., Piotti, A., Geiger, W., Benassi, G. & Menozzi, P. 2010: Genetic structure of Austrian and Italian populations of Limnocythere inopinata (Crustacea, Ostracoda): a potential case of post-glacial parthenogenetic invader? — Ann. Zool. Fennici 47: 133–143.
Several hypotheses were proposed to account for geographic parthenogenesis that is the disjointed distribution of a species’ sexual and asexual forms. In the areas affected by glaciations the parthenogenetic forms would have had ecological success and hybridization and polyploidy would have been the driving forces in their success. Limnocythere inopinata is well-represented in Quaternary non-marine sequences and is useful for studying the evolution of geographic parthenogenesis. We analysed the genetic variability of twelve populations from sub alpine Italian lakes, Austrian lakes and a pond, in an area that was covered by ice during the Pleistocene. In all samples we found only parthenogenetic females. Using allozymes, we described at least 33 different clonal lineages in the total of 812 females. We found no evidence for polyploidy. Clonal diversity is relatively high and may reflect the genetic diversity of ancestral sexual metapopulations. In L. inopinata, geographical parthenogenesis seems the result of historical and ecological factors and is not linked to polyploidy and hybrid advantage.
Mitrus, C., Mitrus, J. & Sikora, M. 2010: Sex differences in the rate of food provisioning to nestlings red-breasted flycatchers (Ficedula parva). — Ann. Zool. Fennici 47: 144–148.
Parental care is one of the crucial factors affecting breeding success in birds. The level of parent investment can differ between males and females. We studied the sex-specific nestling-feeding effort by parents of the red-breasted flycatcher. Our study was carried out in the old-growth oak–lime–hornbeam stands in the Białowieża National Park (NE Poland). The frequency of nestling-feeding and relative nestling-feeding effort (number of visits by male or female expressed a percentage of all visits by both sexes at the nest) depended on sex of parents and age of nestlings but not on their number. Both sexes increased their feeding frequency as the nestlings became older. Sex differences in nestling-feeding have been found in a number of biparental-care bird species. There are many hypotheses to explain this phenomenon. In the red-breasted flycatcher, the most likely reason for differences in feeding efforts are differences in roles the parents play at different stages of brood develompent.
Vakirtzis, A. & Roberts, S. C. 2010: Mate quality bias: Sex differences in humans. — Ann. Zool. Fennici 47: 149–157.
In mate choice copying, a male is more likely to be chosen by other females simply by being observed mating. A recent finding is that women are influenced in their assessments of men by the phenotypic quality of males' sexual partners. We recently proposed that the term 'mate quality bias' should be used to differentiate this phenomenon from 'mate choice copying'. Here, under the guise of a dating preferences survey we replicated and extended some earlier results. We found that when presented to female raters, men are more desirable dates when they are depicted as having had relatively attractive (versus relatively unattractive) former partners, an effect that appears to be moderated by a second variable, namely the former partner's age. We did not find evidence for this bias effect when men rate women whose profiles have been similarly manipulated. These findings suggest the operation of a sex-specific mate choice mechanism.