Jussi Viitala

Ultraviolet reflection and female mate choice in the pied flycatcher, Ficedula hypoleuca

In pied flycatchers females seem to prefer male territory quality rather than male characteristics, and the results of female mate choice experiments are divergent. In this outdoor aviary study, we examined how altering the ultraviolet reflection of males affects female mate choice behaviour. We chose pairs of males with similar human-visible dorsal colour and morphological traits. We then reduced the proportional ultraviolet reflectance in one male with sunscreen chemicals. The other male was treated with a chemical that slightly increased the ultraviolet reflectance of the plumage. In the experiment females clearly preferred males with slightly increased ultraviolet reflection. Our results indicate that pied flycatcher females use ultraviolet cues for mate choice when the effect of territory quality is controlled for. The results give us new information about a possible mechanism of mate assessment in this species, and indicate the importance of colour cues in avian mate choice behaviour.

HIGHER REPRODUCTIVE SUCCESS AMONG KIN GROUPS OF BANK VOLES (CLETHRIONOMYS GLAREOLUS)

According to the kin selection theory the degree of genetic relatedness affects the nature of intraspecific competition and it might promote cooperative and/or altruistic behavior between individuals. We examined kinship effects on reproductive success of territorial females and survival of juveniles in the bank vole Clethrionornys glnreolus. Four experimental populations were founded in large enclosures (0.5 ha): two consisted of five related (Related, R) and two of five mutually unrelated females (Unrelated, UR). Each population had five males of heterogeneous origin. Our earlier results showed that populations of the R grew twice as fast as the UR. Here we show that recruitment and offspring survival is connected to spacing behavior of mothers. Unrelated females who had their home ranges close to each other produced significantly fewer recruits than the related ones. Their home ranges overlapped significantly less and ranges were smaller if they were situated close to each other. Furthermore, the survival of juveniles declined with dispersal distance from the natal territory in populations of the UR. Trappabilities of juveniles were also lower among the young whose home ranges were close to unrelated females, indicating avoidance of mature females. Our results indicate that competition for space is more intense among unrelated neigh- bors, decreasing their reproductive success. Infanticide towards unrelated nestlings and/or juveniles is one possible mechanism decreasing survival and causing a lower recruitment of young. On the contrary, sharing of space among related neighbors did not seem to cause notable costs on their reproduction. Mature females allowed related young females to use their territory, but still, the young did not acquire an area for their own reproduction, probably due to a mother-daughter conflict. The basic social structure of Clethrionor?zys populations, i.e., exclusive female territoriality, remained the same regardless of a high degree of relatedness.

Rough-legged Buzzards use vole scent marks to assess hunting areas

Voles scent mark their territories with urine and faeces that are visible in ultraviolet (UV) light. Rough-legged Buzzards Buteo lagopus feed mainly on voles. We performed a field experiment in northern Finland to test whether buzzards are attracted to UV-visible vole scent marks. The buzzards hunted more often on plots with vole scent marks than on control plots. Our results indicate that Rough-legged Buzzards may be able to use vole scent marks as a cue when searching for profitable hunting and breeding areas.

Different demography of friends and strangers: an experiment on the impact of kinship and familiarity in Clethrionomys glareolus

SummaryWe examined demographic effects of familiarity and relatedness in the bank vole Clethrionomys glareolus (Schreber) in four 0.5-ha enclosures in Central Finland. In two enclosures were mature voles which had overwintered together and some of their mature off-spring (hereafter referred to as “Friends”), and in the other two individuals of the same species captured from different localities near the study area (“Strangers”). The experiment lasted from June to September. The populations of Friends reached densities twice as high as those of Strangers with a significantly higher rate of recruitment and survival of the young. This may have been due to mutual familiarity decreasing antagonism towards the juveniles. The conflicting results obtained from studies of Clethrionomys and Microtus are discussed. We believe that these genera represent behavioural adaptations to different habitats and ways of life. Most behavioural population regulation hypotheses are based on studies of Microtus. We conclude that these results should be applied with great caution to other rodent genera.

Do Tengmalm's owls see vole scent marks visible in ultraviolet light?

Scent markings (urine and faeces) of small mammals are visible in ultraviolet (UV) light. Diurnal kestrels, Falco tinnunculususe them as a cue to find areas of food abundance. We studied whether vole-eating, nocturnal Tengmalms owls, Aegolius funereuscan see vole scent marks using UV-vision. In a laboratory experiment, 14 young (less than 6 months old) and 14 adult (more than 6 months old) owls were individually given a choice between four adjacent arenas: (1) an arena with vole urine and faeces in UV light; (2) an arena with vole urine and faeces in visible light; (3) a clean arena in UV light; and (4) a clean arena in visible light. Owls did not prefer any of the four arenas. Our results suggest that Tengmalms owls probably do not use UV light as a cue to detect vole scent marks.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Kestrels prefer scent marks according to species and reproductive status of voles

AbstractWe have previously documented that European kestrels (Falco tinnunculus L.) are attracted to the scent marks of small rodents in the presence of ultraviolet light (UV) but not visible light...

A Comparative Study of Phenotypic Changes in Microtus Social Organization

Monogamy, polygyny, and promiscuity have been found in populations of M. oeconomus and M. agrestis in different environmental situations in northern Finland. Thus the mating systems seem to be more variable both between and within species in Microtus than in Clethrionomys. Spacing behavior in Microtus caused a temporary decline in population density in mid-summer, but in Clethrionomys a decline occurred only in the beginning of the breeding season. Habitat quality affected spacing behavior in similar ways in Microtus and Clethrionomys but did not affect differences in breeding limitation. Despite the differences in population regulation, both Clethrionomys and Microtus populations cycle synchronously in northern Fennoscandia.