Moskát, C. 2005: Nest defence and egg rejection in great reed warblers over the breeding cycle: are they synchronised with the risk of brood parasitism? — Ann. Zool. Fennici 42: 579–586.

In avian host–brood parasite co-evolution, hosts develop antiparasite defence mechanisms against the brood parasite. Great reed warblers (Acrocephalus arundinaceus) exhibit intensive nest defence against common cuckoos (Cuculus canorus) and moderate egg rejection. Rejection of model cuckoo eggs is about two times greater than real eggs. Great reed warblers attacked a mounted cuckoo at nests in similarly high frequencies over the breeding cycle (86%–93%), but rejection rates of non-mimetic model cuckoo eggs increased from laying until early incubation from 69% to 92%, then decreased to 44% in late incubation. Temporal changes in the risk of parasitism were followed by the changes in egg rejection suggesting that egg rejection behaviour is primarily a risk-sensitive adaptation to brood parasitism, although hosts were not able to switch off egg rejection totally in the risk-free periods. In contrast, nest defence seems to be the compound effect of antiparasite defence and predator avoidance.

Back to the top

Rönkä, M. T. H., Saari, C. L. V., Lehikoinen, E. A., Suomela, J. & Häkkilä, K. 2005: Environmental changes and population trends of breeding waterfowl in northern Baltic Sea. — Ann. Zool. Fennici 42: 587–602.

Causes behind the changes in waterfowl populations in the Archipelago Sea, SW Finland, have until now not been quantitatively analysed. We modelled the impact of eutrophication, winter severity, weather conditions during breeding and water salinity on the breeding populations of ten waterfowl species (ducks, great crested grebe Podiceps cristatus and coot Fulica atra) using generalised linear models and the program TRIM (TRends and Indices in Monitoring data). The populations of the goldeneye Bucephala clangula, coot and velvet scoter Melanitta fusca decreased with increasing eutrophication. The populations of the goldeneye, coot, mallard Anas platyrhynchos, mute swan Cygnus olor and eider Somateria mollissima were most vulnerable to winter severity. We did not find evidence for impacts of weather conditions during breeding or water salinity on population trends. We also discuss alternative explanations to the observed population trends, such as predation and disturbance.

Back to the top

Evans, A. R., Hunter, J., Fortelius, M. & Sanson, G. D. 2005: The scaling of tooth sharpness in mammals. — Ann. Zool. Fennici 42: 603–613.

The scaling of many aspects of mammalian biology remains to be thoroughly investigated. Isometric scaling of tooth sharpness over very large body size ranges appears unlikely from a theoretical viewpoint, as geometrically similar teeth will function differently in a masticatory system that scales isometrically. Taking into consideration developmental controls on tooth shape and the effects of tooth wear, tooth sharpness is predicted to be highest in small animals, with relatively lower tooth sharpness in medium and large animals. The results for small to large mammals (1–2500 kg) are reassessed to show that in this range of body size there is no isometric scaling in this body size range and that wear is probably the primary determinant of sharpness, producing sharpness that is relatively scale-independent when sufficient wear occurs. Including limited additional data on tooth sharpness for very small mammals (Microchiroptera) suggests that there may be an overall trend of isometry for functional tooth crests over the very broadest range in size (0.008–2500 kg), a hypothesis that can be tested in the future with broader taxonomic sampling.

Back to the top

Koivula, M. J., Kotze, D. J. & Salokannel, J. 2005: Beetles (Coleoptera) in central reservations of three highway roads around the city of Helsinki, Finland. — Ann. Zool. Fennici 42: 615–626.

Central reservations, also known as median strips, are strips of ground, usually paved or landscaped, that divide the carriageways of a highway. We trapped beetles in vegetated central reservations of three Ring Roads around the city of Helsinki, Finland, in 2002, and collected a total of 1512 individuals and 110 species. Ground beetles were the most abundant beetle family collected with 749 individuals and 29 species, followed by rove beetles (410 individuals, 31 species) and weevils (131 individuals, 15 species). Central reservations of the most recently constructed Ring Road II collected significantly more ground-beetle species and rove-beetle individuals than the two older roads (Ring Roads I and III). However, in Ring Road III we collected slightly more weevil individuals, and significantly more individuals of the rest of the beetles. As expected, most species collected were associated with open habitats, eurytopic and capable of flight. Regarding species characteristics, the three roads differed with respect to their catches of short-winged, saprophagous, predator/mixed-diet, small-sized (3.1–6 mm), common and nationally rare species, whereas the occurrences of long-winged, plant-eating, very small (< 3 mm), large (> 6 mm) and moderately common species were more even. Non-metric Multidimensional Scaling demonstrated that the beetle community of the central reservations of Ring Road II was different from the communities of Ring Roads I and III. There appeared to be more within-road variation in community structure at these last two roads. Catches of the nationally vulnerable carabid Amara equestris, and several considered rare species, indicate that central reservations have conservation potential.

Back to the top

Honza, M. & Moskát, C. 2005: Antiparasite behaviour in response to experimental brood parasitism in the great reed warbler: a comparison of single and multiple parasitism. — Ann. Zool. Fennici 42: 627–633.

Rejection of parasitic eggs is one of the most important adaptations of avian hosts against brood parasites. Multiple brood parasitism is relatively rare in hosts of the common cuckoo (Cuculus canorus), but naturally occurs when the rate of parasitism is high. We experimentally parasitised great reed warbler (Acrocephalus arundinaceus) clutches with non-mimetic and moderately mimetic model cuckoo eggs. In the case of single parasitism, each egg type was rejected at the same rate (68%–75%), but in the case of multiple parasitism, the rejection rate significantly increased to 96%. So multiple parasitism is in some way facilitating anti-parasite behaviour in the host. We suggest that when parasitism rate reaches high levels, e.g. at the beginning of the coevolutionary arms race, multiple parasitism may be an important component of the host's adaptation to brood parasitism in general.

Back to the top