Search results for "Overwintering"
showing 10 items of 55 documents
Life in the ice lane: the winter ecology of stream salmonids
2007
Despite the common view that conditions in winter strongly influence survival and population size of fish, the ecology of salmonids has not been as extensively studied in winter as in other seasons. In this paper, we review the latest studies on salmonid winter survival, habitat use, movement and biotic interactions as they relate to the prevailing physical and habitat conditions in rivers and streams. The majority of research conducted on the winter ecology of salmonids has been carried out in small rivers and streams, where temperatures are above zero and where there is no ice. Investigations in large rivers, regulated and dredged rivers, and under conditions of different ice formations a…
Temporal variation in reproductive allocation in a shield bug Elasmostethus interstinctus
1996
We investigated changes in the reproductive output and the effect of female phenotype on reproductive parameters in a shield bug Elasmostethus interstinctus (L.) (Heteroptera: Acanthosomatidae) over the whole reproductive period. At the beginning and the middle of the reproductive period eggs were smaller than at the end of the period. Clutch mass and number of eggs per clutch decreased in laying sequence, first clutches being much larger than any of the later ones. Lifetime fecundity correlated positively with female size: large females produced more eggs and lived longer than small ones. Egg size did not vary with female size. Offspring survival until adulthood increased with egg weight. …
Energy use, diapause behaviour and northern range expansion potential in the invasive Colorado potato beetle
2011
Summary 1. As organisms expand their range towards northern latitudes they will encounter selective factors like harsh winter conditions. The ability to cope with and adapt to harsh winters may depend on the variability and evolutionary potential of relevant traits. 2. One adaptation in insects is winter diapause. It is characterized by changes in physiology, behaviour or in both. Physiological changes include lowered metabolic rate that enhances survival by saving limited energy reserves during overwintering. Active behavioural changes like burrowing into the soil allow individuals to escape harsh conditions. 3. We examined variation in overwintering body mass, resting metabolic rate (CO2 …
Energy metabolism and metabolic rate of the alder leaf beetle Agelastica alni (L.) (Coleoptera, Chrysomelidae) under aerobic and anaerobic conditions…
2003
In early fall, adult alder leaf beetles (Agelastica alni L.) retreat, for overwintering, to the top layer of the soil near their forage trees where the ground gets easily waterlogged so that the beetles will be submerged and cut off from atmospheric oxygen. Hence, unlike most other adult insects, alder leaf beetles encounter hypoxia/anoxia in their natural habitat and this may occur at moderate temperature. Exposing beetles to pure nitrogen gas at 20 degrees C had similar behavioral and metabolic effects as submerging them in water, causing rapid immobility and increasing the content of lactate about sevenfold to some 5mgr;molg(-1) body weight during 10h anoxia. Recovery from 10 h hypoxia/a…
Northward range expansion requires synchronization of both overwintering behaviour and physiology with photoperiod in the invasive Colorado potato be…
2014
Abstract. Photoperiodic phenological adaptations are prevalent in many organisms living in seasonal environments. As both photoperiod and growth season length change with latitude, species undergoing latitudinal range expansion often need to synchronize their life cycle with a changing photoperiod and growth season length. Since adaptive synchronization often involves a large number of time-consuming genetic changes, behavioural plasticity might be a faster way to adjust to novel conditions. We compared behavioural and physiological traits in overwintering (diapause) preparation in three latitudinally different European Colorado potato beetle (Leptinotarsa decemlineata) populations reared u…
Resident and transient dynamics, site fidelity and survival in wintering Blackcaps Sylvia atricapilla: evidence from capture-recapture analyses
2007
In their winter quarters, migrant birds may either remain within a small area (resident strategy) or move frequently over a large area looking for locally abundant food (transient strategy). It has been suggested that both strategies could simultaneously occur in the same population. We used time-since-marking capture‐recapture models to infer the coexistence of these two behavioural strategies (transient and resident) among wintering Blackcaps Sylvia atricapilla using weekly recapture data over a 7-year period. A related question is whether Blackcaps, if surviving to the next winter, always return to the same wintering area, so we also used this approach to analyse winter site fidelity and…
Social overwintering and food distribution in the bank vole Clethrionomys glareolus
1991
We studied overwintering in the bank vole Clethrionomys glareolus in four 0.5 ha enclosures in an abandoned field in central Finland in the winter 1987/88. In two of the enclosures food was offered evenly distributed over the whole enclosed area (Even Enclosures = EE), in the two others food was offered in one feeding patch with four feeding chambers 2 m apart (Patchy Enclosures = PE). Food was provided in about the same amount in both enclosures. The experiment commenced in early October, with 13 females and 11 males in EEs and 12 + 13 voles in PEs. After two months the voles in the PEs were concentrated around the feeding patches. Territoriality was not observed in EEs, instead the voles …
Food resources and intestinal parasites as limiting factors for boreal vole populations during winter
2014
Processes limiting the growth of cyclic vole populations have stimulated considerable research and debate over several decades. In Fennoscandia, the peak density of cyclic vole populations occurs in fall, and is followed by a severe winter decline. Food availability and intestinal parasites have been demonstrated to independently and synergistically limit wildlife populations. The purpose of this study was to directly compare competing food and parasite hypotheses on the limitation of overwintering high-density vole populations. Moreover, we evaluated the ability of food limitation and nematode infection to interact and thereby intensify population declines. A two-factor experiment with foo…
Life in varying environments: experimental evidence for delayed effects of juvenile environment on adult life history
2011
Summary 1. The effects of environment experienced during early development on phenotype as an adult has started to gain vast amounts of interest in various taxa. Some evidence on long-term effects of juvenile environment is available, but replicated experimental studies in wild animals are still lacking. 2. Here we report the first replicated experiment in wild mammals which examines the long-term effects of juvenile and adult environments on individual fitness (reproduction, survival and health). The early development of bank vole (Myodes glareolus) individuals took place in either foodsupplemented or un-supplemented outdoor enclosures. After the summer, adult individuals were reciprocally…