0000000001328376
AUTHOR
Esa Huhta
Island selection on mammalian life-histories: genetic differentiation in offspring size
Abstract Background Since Darwin's pioneering work, evolutionary changes in isolated island populations of vertebrates have continued to provide the strongest evidence for the theory of natural selection. Besides macro-evolutionary changes, micro-evolutionary changes and the relative importance of natural selection vs. genetic drift are under intense investigation. Our study focuses on the genetic differentiation in morphological and life-history traits in insular populations of a small mammal the bank vole Myodes glareolus. Results Our results do not support the earlier findings for larger adult size or lower reproductive effort in insular populations of small mammals. However, the individ…
Effects of forest patch size on physiological stress and immunocompetence in an area-sensitive passerine, the Eurasian treecreeper ( Certhia familiaris ): an experiment
We manipulated the primary brood size of Eurasian treecreepers (Certhia familiaris) breeding in different sized forest patches (0.5-12.8 ha) in moderately fragmented landscapes. We examined the effects of brood size manipulation (reduced, control, enlarged) and forest patch size on physiological stress (heterophil-lymphocyte ratios; H/L), body condition and cell-mediated immunocompetence (phytohaemagglutinin test). Nestlings' H/L ratios were negatively related to forest patch area in control and enlarged broods, whereas no effects were found in reduced broods. The effects of forest patch area were strongest in enlarged broods, which had, in general, twofold higher H/L ratios than control an…
Thresholds in selection of breeding habitat by the Eurasian treecreeper (Certhia familiaris)
Abstract Assessment of habitat thresholds is a topical issue in ecology, both from theoretical and applied perspectives. We examined how forest structure influences selection of breeding habitat in the Eurasian treecreeper (Certhia familiaris). It is an old-growth forest passerine, which can be considered an umbrella species. Habitat selection data, covering five breeding seasons, were collected from a study area across three spatial scales: (a) territory core scale (a radius of 30 m), (b) territory scale (a radius of 200 m) and (c) large scale (a radius of 500 m). Logistic regression analyses revealed that the radii of 30 and 200 m from the nest were the most important spatial scales for t…
Individual color variation and male quality in pied flycatchers (Ficedula hypoleuca): a role of ultraviolet reflectance
Bright coloration of males in many animal species has inspired researchers for more than a century. In this field study, we investigated whether color variation between individuals is related to individual quality in pied flycatcher (Ficedula hypoleuca) males in terms of arrival time at the breeding sites. In addition to traditional visual color scoring, plumage color was measured using spectroradiometric measurements between 320 and 700 nm. This range includes the near-ultraviolet waveband from 320 to 400 nm. Males that arrived earlier at breeding sites had higher proportional UV reflectance in the crown and mantle. The proportional UV reflectance in the crown and mantle was not related to…
Leucocytozoon muscicapa n. sp. (Leucocytozoidae: Apicomplexa) from the pied flycatcherFicedula hypoleuca (Pallas) (Passeriformes: Muscicapinae)
Leucocytozoon muscicapa n. sp. is described from the pied flycatcherFicedula hypoleuca (Pallas) (Passeriformes: Muscicapinae) from Finland and compared with other leucocytozoids of the family Muscicapidae.
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 result…
Small Scale Geographical Variation in Plumage Colour of Pied Flycatcher Males
Ecology -94". A cruise report. Swedish Polar Research Secretariat, Stockholm, pp. 311-316. Lundgren, B., Hedenstr6m, A. and Pettersson, J. 1995. Correlation between some body components and visible fat index in the Willow Warbler Phylloscopus trochilus (L.). Ornis Svecica 5: 75-79. Pettersson, J. and Hasselquist, D. 1985. Fat deposition and migration capacity of Robins Erithacus rubecula and Goldcrests Regulus regulus at Ottenby, Sweden. Ring. & Migr. 6: 66-76. Piersma, T., Bruinzeel, L., Drent, R., Kersten, M., Van der Meer, J. and Wiersma, P. 1996. Variability in basal metabolic rate of a long-distance migrant shorebird (Red Knot, Calidris canutus), reflects shifts in organ sizes. Physiol…
Forest Fragmentation Increases Nest Predation in the Eurasian Treecreeper
We used long-term breeding data to monitor the influences of fragmentation and habitat composi- tion at different spatial scales on the reproductive success of Eurasian Treecreepers (Certhia familiaris) breeding in nest boxes. We collected data from the same forest patches (2.7-65.1 ha in size) during seven breeding sea- sons. Nest predation varied considerably over the years and was the primary cause of nesting failure (mean annual rate of 21.6 ± 12.8%). Nest predation explained most of the variation in fledgling production during the study period. Landscape-level fragmentation (radius of 500 m from territory center) affected nest predation more than did fragmentation on the territory scal…
Eimeria-parasites are associated with a lowered mother's and offspring's body condition in island and mainland populations of the bank vole.
This study, based on correlative data, tests the hypothesis that infections withEimeriaspp. parasites exert a significant loss of fitness of bank voles (Clethrionomys glareolus) reflected in lower reproductive success and survival, declining host population densities and are associated positively with population size. The study was conducted in 20 mainland and 27 island populations in central Finland during May–September in 1999. Faecal samples showed that 28% of 767 individuals were infected withEimeriaspp. The presence ofEimeriaparasites was higher in dense mainland populations than in sparsely populated islands. Eimerian infections increased during the course of the breeding season, prob…
Within territory abundance of red wood ants Formica rufa is associated with the body condition of nestlings in the Eurasian treecreeper Certhia familiaris
Studies on individual reproductive success in relation to interspecific competition between distantly related taxa are scarce. We studied whether the abundance of red wood ants Formica rufa -group is related to the breeding habitat selection, fecundity and offspring quality in the Eurasian treecreeper Certhia familiaris, an old-growth forest passerine. The nest-box occupancy data were gathered over a five-year study period, whereas the breeding performance analyses were based on a two-year data set. The abundance of wood ants, measured within 50 m around the nest-boxes, was not related to nest-box occupancy rate, fecundity or the physiological stress of nestlings. In contrast, the abundance…
Plumage colour and male-male interactions in the pied flycatcher
Abstract Abstract. The influence of male colour on male-male interactions in the pied flycatcher, Ficedula hypoleuca , was studied using several types of field experiments. This species exhibits delayed plumage maturation, each male becoming more conspicuously black and white from the first to the second breeding summer. However, individual males vary even more, some old males being as brown as females. When territorial males were presented with a choice between brown and black male intruders (or brown males painted black) they directed more aggression towards the black males. Brown plumage did not help males obtain nestboxes close to other males. If anything browner males were at a disadva…
Habitat-related nest predation effect on the breeding success of the Eurasian treecreeper
We studied the impact of habitat structure on the long-term breeding success of an old-growth forest passerine the Eurasian treecreeper (Certhia familiaris) assessed over a period of 7 years in the...
Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris).
We studied the primary brood sex ratio of an old-growth forest passerine, the Eurasian treecreeper (Certhia familiaris), along a gradient of forest fragmentation. We found evidence that male nestlings were more costly to produce, since they suffered twofold higher nestling mortality and were larger in body size than females. Furthermore, the proportion of males in the brood was positively associated with the provisioning rate and the amount of food delivered to the nestlings. During the first broods, a high edge density and a high proportion of pine forests around the nests were related to a decreased production of males. The densities of spiders, the main food of the treecreeper, were 38% …
Effects of spatial scale and vegetation cover on predation of artificial ground nests
Scale-dependent effects of landscape heterogeneity on predation of artificial ground nests were studied. Two spatial scales were selected: landscape grain size and single stand size. The landscape types did not differ from each other in their total predation intensity. Depredation was highest in larger stands in all the landscape types studied and the highest predation rate was detected in the largest stands within the most fragmented landscapes. This is possibly due to concentration of rodent-eating predators from surrounding open areas into large stands in the study year when their main prey, voles, crashed. In crash years, alternative predation on e.g. forest bird nests may play an impor…
Predation on artificial ground nests in relation to forest fragmentation, agricultural land and habitat structure
The impacts of forest fragmentation, agricultural land and habitat structure on depredation of artificial ground nests were studied in the cultivated area in central Finland and in the forest dominated area in Finnish Lapland. The overall predation rate did not differ between the regions. The overall predation rate was also independent of landscape characteristics forest patch size and the distance to patch edge. However, nest predation was clearly affected by the agricultural land since the robbing rate in forest edges was higher near farmlands than further away. This effect was caused by avian predators which proportional importance in predation was higher in the agricultural landscape th…
A test of male mating and hunting success in the kestrel: the advantages of smallness?
We tested female choice for male wing and tarsus length and body mass in the kestrel (Falco tinnunculus), a species in which males average about 10% smaller than females. We also studied how male characters are related to their hunting success. In the laboratory, females preferred lighter males with shorter tarsi as mates, if the difference in those characters between competing males was larger than average. Lighter and shorter-winged males seemed to be better hunters than heavier and longer-winged males. Field observations in a year in which voles were scarce suggested that shorter-winged males were also better food providers in courtship feeding than longer-winged males,although in good v…
Forest management is associated with physiological stress in an old–growth forest passerine
We investigated how physiological stress in an area-sensitive old-growth forest passerine, the Eurasian treecreeper (Certhia familiaris), is associated with forest fragmentation and forest structure. We found evidence that the concentrations of plasma corticosterone in chicks were higher under poor food supply in dense, young forests than in sparse, old forests. In addition, nestlings in large forest patches had lower corticosterone levels and a better body condition than in small forest patches. In general, corticosterone levels were negatively related to body condition and survival. We also found a decrease in corticosterone levels within the breeding season, which may have been a result …
Urbanization and stability of a bird community in winter
Abstract: The main objective of this study was to analyze between-winter stability of bird communities along latitudinal (950 km) and urban gradients (from small village to towns) in Finland. Birds were surveyed at the same 30-ha study plots using the same methods in 31 villages and town centres in the winters of 1991–1992 and 1999–2000. Species richness did not differ between the 2 study winters, but variation in total abundance of birds increased with increasing urbanization. However, urbanization reduced variation in wintering bird community structure. Species richness, density of wintering birds, and dissimilarity of wintering bird communities did not vary with latitude. According to ou…
Delayed maturation in plumage colour: Evidence for the female-mimicry hypothesis in the kestrel
In many sexually dichromatic species, young males have female-like plumage during their first potential breeding year. The female-mimicry hypothesis (FMH) supposes that by possessing female-like plumage young males deceive older conspicuous males into believing that they are females, thus reducing competition from adult males. The status-signalling hypothesis (SSH) supposes that adult males can distinguish sex, but postulates that young males reduce competition from adult males by reliably signaling low status with their dull plumage. We tested these hypotheses in the European kestrel (Falco tinnunculus). Female-like young males settled to breed closer to adult males than did other adult ma…
The effect of human-modified landscape structure on forest grouse broods in two landscape types
The population sizes and the breeding success of Finnish tetraonids have been decreasing for decades. In this study, the presence of a grouse hen with a brood in a landscape was used to indicate habitat-related breeding success. We combined the locations of 938 black grouse (Tetrao tetrix), 388 capercaillie (T. urogallus), and 917 hazel grouse (Tetrastes bonasia) broods after the breeding season in mid-August with landscape data by employing Geographic Information Systems (GIS) and grouse data derived from the Finnish wildlife triangle censuses conducted during 1997–2004. Two large study areas with different landscape structures; northern forest-mire area and southern cultivated area, were …
Island selection on mammalian life-histories: genetic differentiation in offspring size
BACKGROUND: Since Darwin's pioneering work, evolutionary changes in isolated island populations of vertebrates have continued to provide the strongest evidence for the theory of natural selection. Besides macro-evolutionary changes, micro-evolutionary changes and the relative importance of natural selection vs. genetic drift are under intense investigation. Our study focuses on the genetic differentiation in morphological and life-history traits in insular populations of a small mammal the bank vole Myodes glareolus. RESULTS: Our results do not support the earlier findings for larger adult size or lower reproductive effort in insular populations of small mammals. However, the individuals li…