Winter Ecology
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Recent papers in Winter Ecology
Hatchling emergence patterns were studied in a community of six species of freshwater turtles in Lancaster County, Pennsylvania, USA, including: Chelydra serpentina, Chrysemys picta, Clemmys guttata, Glyptemys insculpta, Glyptemys... more
Hatchling emergence patterns were studied in a community of six species of freshwater turtles in Lancaster County, Pennsylvania, USA, including: Chelydra serpentina, Chrysemys picta, Clemmys guttata,
Glyptemys insculpta, Glyptemys muhlenbergii, and Sternotherus odoratus. Data were collected every year from 1965–1985 on estimated date of emergence, carapace length, April-May precipitation, August-September precipitation, annual precipitation, and low temperature and occurrence of precipitation during the 24 h prior to the time of each hatchling detection (n 5 806). Chelydra serpentina, Ch. picta, and Cl.
guttata hatchlings have a facultative delayed emergence strategy. The other species (G. insculpta, G. muhlenbergii, and S. odoratus) appear to be obligate early emergers, with the exception of one hatchling G.
muhlenbergii that delayed emergence. Early emergence occurred in some species every year. However, the majority of hatchlings delayed emergence until the year following oviposition, except in 1973, the year
following intense flooding and nest destruction associated with a major hurricane. Mean estimated calendar day of emergence varied annually in C. serpentina and Ch. picta. The same variable also differed among
species for comparisons of both early and delayed emergence. Chelydra serpentina hatchlings emerged earlier than all other species whether they used an early or delayed strategy. Carapace length of Ch. picta
hatchlings varied significantly among years, and C. serpentina hatchlings that delayed emergence were significantly larger in carapace length than those that emerged early. Seasonal and previous 24-h precipitation
had varying effects on the number of emerging hatchlings, but August–September precipitation in one year had a strong correlation with the number of hatchlings that delayed emergence until the following spring.
The number of hatchlings detected peaked at a previous 24-h air temperature of about 12oC for both early and late emergence. Small species like G. muhlenbergii and S. odoratus may emerge early to limit potential hatchling competition in diverse communities of freshwater turtles with primarily delayed emergence.
Glyptemys insculpta, Glyptemys muhlenbergii, and Sternotherus odoratus. Data were collected every year from 1965–1985 on estimated date of emergence, carapace length, April-May precipitation, August-September precipitation, annual precipitation, and low temperature and occurrence of precipitation during the 24 h prior to the time of each hatchling detection (n 5 806). Chelydra serpentina, Ch. picta, and Cl.
guttata hatchlings have a facultative delayed emergence strategy. The other species (G. insculpta, G. muhlenbergii, and S. odoratus) appear to be obligate early emergers, with the exception of one hatchling G.
muhlenbergii that delayed emergence. Early emergence occurred in some species every year. However, the majority of hatchlings delayed emergence until the year following oviposition, except in 1973, the year
following intense flooding and nest destruction associated with a major hurricane. Mean estimated calendar day of emergence varied annually in C. serpentina and Ch. picta. The same variable also differed among
species for comparisons of both early and delayed emergence. Chelydra serpentina hatchlings emerged earlier than all other species whether they used an early or delayed strategy. Carapace length of Ch. picta
hatchlings varied significantly among years, and C. serpentina hatchlings that delayed emergence were significantly larger in carapace length than those that emerged early. Seasonal and previous 24-h precipitation
had varying effects on the number of emerging hatchlings, but August–September precipitation in one year had a strong correlation with the number of hatchlings that delayed emergence until the following spring.
The number of hatchlings detected peaked at a previous 24-h air temperature of about 12oC for both early and late emergence. Small species like G. muhlenbergii and S. odoratus may emerge early to limit potential hatchling competition in diverse communities of freshwater turtles with primarily delayed emergence.
In the northern hemisphere many species of waterfowl breed in the Arctic and migrate to spend the winter at lower latitudes. A growing number of these species are declining in numbers (based on counts undertaken on their wintering... more
In the northern hemisphere many species of waterfowl breed in the Arctic and migrate to spend the winter at lower latitudes. A growing number of these species are declining in numbers (based on counts undertaken on their wintering grounds), including Red-breasted Goose, Dark-bellied Brent Goose, Greenland White-fronted Goose, Taiga Bean Goose, and Bewick’s Swan. Currently, it is unclear for many species whether these population decreases have been caused by lower productivity, lower survival, range shifts, or a combination of all three. To help conserve these declining populations, we need to understand what is causing decreases in numbers. In particular, we need to understand how demographic rates (breeding success and survival) are influenced by environmental variables, and how such rates have changed over time and thus whether they could explain the observed declines.
Many temperate animals spend half their lives in a non-active, overwintering state, and multiple adaptations have evolved to enable winter survival. One notable vertebrate model is Chrysemys picta, whose hatchlings display dichotomous... more
Many temperate animals spend half their lives in a non-active, overwintering state, and multiple adaptations have evolved to enable winter survival. One notable vertebrate model is Chrysemys picta, whose hatchlings display dichotomous overwintering strategies: some hatchlings spend their first winter aquatically after nest emergence in the autumn, whereas others overwinter terrestrially within their natal nest with subsequent emergence in the spring. The occurrence of these strategies varies among populations and temporally within populations; however, factors that determine the strategy employed by a nest in nature are unknown. We examined potential factors that influence intra-population variation in the overwintering strategy of C. picta hatchlings over two winters in Algonquin Park, Ontario. We found that environmental factors may be a trigger for the hatchling overwintering strategy: autumn-emerging nests were sloped towards the water and were surrounded by a relatively higher percentage of bare ground compared with spring-emerging nests. Autumn-emerging hatchlings were also relatively smaller. Overwintering strategy was not associated with clutch oviposition sequence, or mammalian or avian predation attempts. Instead, autumn emergence from the nest was associated with the direct mortality threat of predation by sarcophagid fly larvae. Body condition and righting response, measured as proxies of hatchling fitness, did not differ between overwintering strategies. Costs and benefits of overwintering aquatically versus terrestrially in hatchling C. picta are largely unknown, and have the potential to affect population dynamics. Understanding winter survival has great implications for turtle ecology, thus we emphasize areas for future research on dichotomous overwintering strategies in temperate hatchling turtles.
- by Julia L Riley and +2
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- Herpetology, Winter Ecology
Behavioural polymorphisms associated with morphs with a known genetic basis are interesting to study since they provide a model system to investigate the molecular basis of complex behaviours. Whitethroated sparrows are one of such rare... more
Behavioural polymorphisms associated with morphs with a known genetic basis are interesting to study since they provide a model system to investigate the molecular basis of complex behaviours. Whitethroated sparrows are one of such rare models, presenting two morphologies and behavioural types, tan and white, caused by a chromosomal rearrangement. The behavioural differences have been mainly studied during reproduction, defining two morph-specific breeding strategies and different levels of aggression between morphs. Outside of the breeding season, the morphological differences are less apparent, morphs are more difficult to distinguish and the behavioural polymorphism is poorly understood. In this study, we caught wild individuals during the winter, determined their morph by genetic analysis, and analysed the differences in behaviour between morphs when encountering a novel object under standardized conditions in captivity. White morphs are more aggressive during reproduction; therefore, we expected them to be less affected by the presence of the novel object than tan morphs; animal personality research shows that more aggressive individuals are less affected by the presence of novel objects (i.e. neophilic). Contrary to our expectations, white morphs were more neophobic than tan morphs, and within morphs, males were more neophobic than females. Furthermore, white morph individuals and males of both morphs suffered greater weight loss during captivity compared to tan morphs and females, respectively, suggesting that the response to captivity-induced stress differs between morphs and between sexes. Finding behavioural differences between morphs not related to reproduction implies a broader impact of the effects of the chromosomal rearrangement on the behavioural polymorphism in this species.
Keywords: animal personality behavioural polymorphism novel object test white-throated sparrow Zonotrichia albicollis
Keywords: animal personality behavioural polymorphism novel object test white-throated sparrow Zonotrichia albicollis
– The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we... more
– The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group. Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.
- by Joacim Näslund and +1
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- Salmonids, Growth, Brown trout, Winter Ecology
Decreased snow cover can increase soil freezing, potentially altering soil nitrogen (N) and carbon (C) availability and losses. However, it is unclear how increased soil freezing severity may interact with increased atmospheric N... more
Decreased snow cover can increase soil freezing, potentially altering soil nitrogen (N) and carbon (C)
availability and losses. However, it is unclear how increased soil freezing severity may interact with
increased atmospheric N deposition, and to what extent these effects may extend over multiple growing
seasons in herbaceous systems. We examined the interactive effects of increased soil freezing and N
addition on extractable N and C pools, potential trace gas losses, and microbial biomass in a grassdominated
temperate old field. We used both a snow removal experiment and plant-soil mesocosms
that were frozen under controlled conditions for one week and then returned to the field. For both
experiments, the freezing treatments were only conducted over the first winter, with the legacy effects of
freezing monitored over three subsequent years. As we predicted, soil freezing increased potential trace
gas losses, soil extractable C and N and microbial biomass C and N during the first year, although these
effects were transient. Nitrogen effects, when significant, generally did not interact with freezing. Legacy
effects of snow removal were mostly absent in the second year, but the latter was very dry, and in the
third year the legacy of snow removal resulted in increased extractable nitrate, potential N2O losses and
microbial biomass N, and decreased fungal biomass and microbial biomass C. Overall, our results
demonstrate that while the immediate soil N and C responses to freezing are mostly transient, legacy
effects of soil freezing on soil N and C pools and microbial biomass can persist over multiple years,
possibly as a result of changes to plant productivity and litter deposition.
availability and losses. However, it is unclear how increased soil freezing severity may interact with
increased atmospheric N deposition, and to what extent these effects may extend over multiple growing
seasons in herbaceous systems. We examined the interactive effects of increased soil freezing and N
addition on extractable N and C pools, potential trace gas losses, and microbial biomass in a grassdominated
temperate old field. We used both a snow removal experiment and plant-soil mesocosms
that were frozen under controlled conditions for one week and then returned to the field. For both
experiments, the freezing treatments were only conducted over the first winter, with the legacy effects of
freezing monitored over three subsequent years. As we predicted, soil freezing increased potential trace
gas losses, soil extractable C and N and microbial biomass C and N during the first year, although these
effects were transient. Nitrogen effects, when significant, generally did not interact with freezing. Legacy
effects of snow removal were mostly absent in the second year, but the latter was very dry, and in the
third year the legacy of snow removal resulted in increased extractable nitrate, potential N2O losses and
microbial biomass N, and decreased fungal biomass and microbial biomass C. Overall, our results
demonstrate that while the immediate soil N and C responses to freezing are mostly transient, legacy
effects of soil freezing on soil N and C pools and microbial biomass can persist over multiple years,
possibly as a result of changes to plant productivity and litter deposition.
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