Effect of Seasonal Swings and Age Specific Variations on Body Weight of Indian Gerbille (Tatera indica) (original) (raw)
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Seasonal Body Weight Variation in Five Species of Woodpeckers
The Condor, 2005
We investigated patterns of seasonal variation in body weight in six populations of five resident species of temperate-zone woodpeckers: Acorn Woodpecker (Melanerpes formicivorus), Red-bellied Woodpecker (M. carolinus), Red-cockaded Woodpecker (Picoides borealis), Downy Woodpecker (P. pubescens), and Great Spotted Woodpecker (Dendrocopos major). After controlling for time of day and overall body size, annual variation in body weight was small and generally not statistically significant. However, analysis revealed evidence of significant ''winter fattening,'' comparable in magnitude to other temperate-zone resident species, in three of the species. The degree of winter fattening did not correlate with either the size of the acorn crop (for the Acorn Woodpecker) or latitude, two variables potentially related to predictability of food resources. However, the smaller species exhibited significantly greater winter fattening than the larger species, as predicted by the hypothesis that energy storage should be more important for small-bodied species. Furthermore, the food-storing Acorn Woodpecker exhibited considerably less winter fattening than the nonfood-storing species, supporting the hypothesis that food storage provides an ecological alternative to winter fattening.
Seasonal variation in the length – weight relationships
Length-weight relationship (LWR) and Condition factor (K) of Gymnarchus niloticus from Lekki Lagoon were studied for 24 months to provide useful information for the sustainable development of Gymnarchus niloticus in Lekki lagoon. Samples of G. niloticus caught from the lagoon were obtained from fishers on a bimonthly basis for 24 months. Length – weight data were analyzed and Length – weight relationship graphs were plotted for the dry and wet seasons of the sampling years. The b values in the LWR (W=aLb) varied between 2.56 – 2.60 for the dry seasons and 2.51 – 2.62 for the wet seasons revealing that the somatic growth of G. niloticusat Lekki lagoon had negative allometry. The average condition factor (K) were found to be 0.7113 ± 0.3485 for dry seasons and 0.7047 ± 0.5069 for wet seasons of the sampling period. There was a strong positive correlation (r = 0.99) between the length and weight of fish specimen examined while the Coefficient of determination (R2) varied between 0.9822 – 0.9976 and 0.9951 – 0.9970 for both dry and wet seasons respectively. It was concluded that the data generated will form a baseline tool for effective fisheries management and sustainable exploitation of G. niloticus in Lekki lagoon.
Functional Ecology, 2010
1. In a seasonal environment, subcutaneous energy reserves of resident animals often increase in winter and decline again in summer reflecting gradual seasonal changes in their fattening strategies. We studied changes in body reserves of wintering great tits in relation to their dominance status under two contrasting temperature regimes to see whether individuals are capable of optimizing their body mass even under extreme environmental conditions.2. We predicted that dominant individuals will carry a lesser amount of body reserves than subordinate great tits under mild conditions and that the body reserves of the same dominant individuals will increase and exceed the amount of reserves of subordinates under conditions of extremely low ambient temperatures, when ambient temperature dropped down to −37 °C.3. The results confirmed the predictions showing that dominant great tits responded to the rising risk of starvation under low temperatures by increasing their body reserves and this was done at the expense of their safety.4. Removal experiments revealed that lower body reserves of subordinate flock members are due to the increased intraspecific competition for food under low ambient temperatures.5. Our results also showed that fattening strategies of great tits may change much quicker than previously considered, reflecting an adaptive role of winter fattening which is sensitive to changes in ambient temperatures.
Effects of spring–summer temperature on body mass of chamois
Journal of Mammalogy, 2012
Environmental change, including global warming, can lead to directional changes over time in phenotypic traits such as sex-and age-specific body mass. We evaluated the potential short-term effects of a series of hot and dry springs and early summers on mass of yearling chamois (Rupicapra rupicapra) in 2 populations in the western Alps. Yearling mass decreased in both populations over the study period, but much of this decline seemed to originate from a sharp drop in 2003, after which body mass remained low. Our analysis suggested that this decrease was caused by the additive effects of warm springs and summers over the first 2 years of life. The mass of adult chamois also decreased over time. These results suggest that ongoing warming in the Alps could be a selective pressure on the life history and reproductive strategies of wild ungulates.
Sources of variation in winter basal metabolic rate in the great tit
Functional Ecology, 2007
Basal metabolic rate (BMR) is the most widely used standard measurement of the cost of living. Despite the acknowledged phenotypic flexibility of BMR, little is known about the patterns of variation in wild animal populations. 2. We studied the sources of variation in BMR of great tit Parus major (L.) among individuals from two wild populations: Oulu (northern Finland) and Lund (southern Sweden) during six consecutive years. 3. By means of a multivariate approach, we found year, locality, date, previous week average minimum temperature, age, body mass, and the interaction between locality and year were the factors retained in the final model, together explaining 71·1% of the total variation in BMR. 4. Birds from Oulu ( n = 168) had a higher BMR than Lund birds ( n = 156), and their BMR varied more between years than that of Lund birds. The two populations reacted in the same way to the other sources of variation examined. 5. Great tits from both populations showed a positive relationship between BMR and body mass and a negative relationship between BMR and date, previous week average minimum temperature and age. 6. This study highlights the need to standardize BMR measurements when testing predictions about metabolic rates from individuals of wild populations.
Effects of weather on daily body mass regulation in wintering dunlin
2000
We investigated the influence of changes in weather associated with winter storms on mass balance, activity and food consumption in captive dunlin (Calidris alpina) held in outdoor aviaries, and compared the aviary results with weather-related body mass differences in free-living dunlin collected at Bolinas Lagoon, California. Captive birds fed ad libitum increased their body mass at higher wind speeds and
Ecography, 2006
. How does environmental variation influence body mass, body size, and body condition? Roe deer as a case study. Á Ecography 29: 301 Á308. We tested the influence of population density and of drought intensity (measured as the Gaussen Index in spring and summer of the year of birth) on winter body mass, hind foot length, and body condition of roe deer fawns. Body mass decreased with increasing density and increased with increasing Gaussen Index in summer, in a similar way for both males and females. Hind foot length of males showed the same response. On the other hand, hind foot length of females decreased with increasing density only after dry summers, hence when environmental conditions were very harsh. Body condition was affected neither by density nor by drought intensity. Our results indicate that body mass and size are much better indicators of phenotypic quality than body condition in roe deer. The sex-specific responses of body size to environmental conditions could correspond to a differential allocation in favour of daughters by heavier than average roe deer mothers.