Seasonal Changes In Body Condition Research Articles

Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears.

Body condition is an important determinant of health, and its evaluation has practical applications for the conservation and management of mammals. We developed a noninvasive method that uses photographs to assess the body condition of free-ranging brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. First, we weighed and measured 476 bears captured during 1998–2017 and calculated their body condition index (BCI) based on residuals from the regression of body mass against body length. BCI showed seasonal changes and was lower in spring and summer than in autumn. The torso height:body length ratio was strongly correlated with BCI, which suggests that it can be used as an indicator of body condition. Second, we examined the precision of photograph-based measurements using an identifiable bear in the Rusha area, a special wildlife protection area on the peninsula. A total of 220 lateral photographs of this bear were taken September 24–26, 2017, and classified according to bear posture. The torso height:body/torso length ratio was calculated with four measurement methods and compared among bear postures in the photographs. The results showed torso height:horizontal torso length (TH:HTL) to be the indicator that could be applied to photographs of the most diverse postures, and its coefficient of variation for measurements was <5%. In addition, when analyzing photographs of this bear taken from June to October during 2016–2018, TH:HTL was significantly higher in autumn than in spring/summer, which indicates that this ratio reflects seasonal changes in body condition in wild bears. Third, we calculated BCI from actual measurements of seven females captured in the Rusha area and TH:HTL from photographs of the same individuals. We found a significant positive relationship between TH:HTL and BCI, which suggests that the body condition of brown bears can be estimated with high accuracy based on photographs. Our simple and accurate method is useful for monitoring bear body condition repeatedly over the years and contributes to further investigation of the relationships among body condition, food habits, and reproductive success.

Comparing temporal patterns in body condition of ringed seals living within their core geographic range with those living at the edge

Ecological theory suggests that demographic responses by populations to environmental change vary depending on whether individuals inhabit central or peripheral regions within the species’ geographic range. Here, we tested this prediction by comparing a population of ringed seals Pusa hispida located at high latitudes as part of their core range (core) with a population located at the southern extremity of their range (peripheral). First, we compared the two regions’ environmental trends in timing of sea‐ice breakup and freeze‐up, open‐water duration and the North Atlantic Oscillation (NAO). We found that the core region shifted to progressively warmer conditions in the early 1990s; whereas, in the peripheral region, the warming trend shifted in 1999 to one with no warming trend but high inter‐annual variability. Next, we examined how body condition, inferred from blubber depth, responded to temporal changes in sea‐ice and climatic variables – variables that have been shown to influence ringed seal demography. Core seals displayed minimal seasonal changes in body condition; whereas peripheral seals displayed a 20–60% amplitude seasonal change in body condition with a phase shift to earlier initiation of fat accumulation and loss. Finally, we tested for interannual differences and found that both core and peripheral seals responded similarly with decreased body condition following more positive NAO. Environmental variables influenced body condition in opposite directions between the two regions with core seals declining in body condition with later spring breakup and shorter open‐water duration, whereas peripheral seals showed opposite relationships. Seals living at the core likely benefit from an evolved match between adaptation and environmental variation resulting in dampened seasonal and interannual fluctuations in body condition. Knowledge of how different populations respond to environmental change depending on geographic location within a species range can assist in anticipating population specific responses to climate warming.

Contrasting the suitability of shade coffee agriculture and native forest as overwinter habitat for Canada Warbler (Cardellina canadensis) in the Colombian Andes

AbstractIn the Neotropics, coffee production occurs on a large scale in some of the planet’s most biodiverse regions: tropical mountains. Coffee production systems involving shade trees are considered to have a lower impact on biodiversity than alternative sun coffee. To date, the majority of evidence for the value of shade coffee plantations has not taken into account the relative quality of this habitat compared to the native forests they replaced. We determined the suitability of shade coffee and forest as winter habitat for Canada Warbler (Cardellina canadensis) by comparing variation in the likelihood of capturing individuals, seasonal changes in body condition, and estimates of annual survival between the 2 habitats. We also determined the effect of the strong 2015–2016 El Niño event on survival. Males were relatively more likely to be captured in forest than females and this likelihood increased during drier years. Body condition change over the winter and apparent annual survival were similar for individuals that used forest and coffee. However, condition and survival decreased in both habitats during the El Niño year. Apparent survival was also lower for individuals carrying a radiotag or geolocator. Our findings suggest that shade coffee with high canopy cover and height offers similar benefits to forest in terms of body condition and survival. Landscape conservation approaches, promoting diverse matrices of structurally complex shade coffee and forest might best ensure long-term survival in Neotropical migrants like Canada Warbler.

Correlates of seasonal change in the body condition of an Arctic top predator.

Climate-driven sea ice loss has led to changes in the timing of key biological events in the Arctic, however, the consequences and rate of these changes remain largely unknown. Polar bears (Ursus maritimus) undergo seasonal changes in energy stores in relation to foraging opportunities and habitat conditions. Declining sea ice has been linked to reduced body condition in some subpopulations, however, the specific timing and duration of the feeding period when bears acquire most of their energy stores and its relationship to the timing of ice break-up is poorly understood. We used community-based sampling to investigate seasonality in body condition (energy stores) of polar bears in Nunavut, Canada, and examined the influence of sea ice variables. We used adipose tissue lipid content as an index of body condition for 1,206 polar bears harvested from 2010-2017 across five subpopulations with varying seasonal ice conditions: Baffin Bay (October-August), Davis Strait and Foxe Basin (year-round), Gulf of Boothia and Lancaster Sound (August-May). Similar seasonal patterns were found in body condition across subpopulations with bears at their nadir of condition in the spring, followed by fat accumulation past break-up date and subsequent peak body condition in autumn, indicating that bears are actively foraging in late spring and early summer. Late season feeding implies that even minor advances in the timing of break-up may have detrimental effects on foraging opportunities, body condition, and subsequent reproduction and survival. The magnitude of seasonal changes in body condition varied across the study area, presumably driven by local environmental conditions. Our results demonstrate how community-based monitoring of polar bears can reveal population-level responses to climate warming in advance of detectable demographic change. Our data on the seasonal timing of polar bear foraging and energy storage should inform predictive models of the effects of climate-mediated sea ice loss.

Fit is fat: winter body mass of Atlantic Puffins Fratercula arctica

ABSTRACTCapsule: Atlantic Puffins Fratercula arctica from Scottish and Norwegian populations were significantly heavier in winter than when rearing chicks.Aims: To compare body masses of Atlantic Puffins on their wintering grounds off the Faroe Islands with those of birds rearing chicks at colonies in Scotland and Norway.Methods: We took standardized measurements of wing length and body mass of Atlantic Puffins during the summer chick-rearing period and on the wintering grounds near the Faroe Islands. These measurements were used to estimate seasonal changes in body mass for the two breeding populations. In three cases data were available for individuals weighed both at the colony and on the wintering grounds.Results: On average, Atlantic Puffins breeding in Scotland and Norway increased their body mass by 20–30% between the chick-rearing period and winter. The very limited individual level data accorded well with the population level estimates.Conclusions: Our results provide the first estimates of the order of magnitude in mass change between two key life history stages in this species. They indicate that gains in body mass between chick-rearing and winter are at least double the decline in mass previously recorded between incubation and chick-rearing. Given the Atlantic Puffin’s deteriorating conservation status, improved information on seasonal changes in body condition should help determine the underlying causes of die-offs in major wreck incidents such as those reported in recent years.

Seasonal Changes in Body Condition of Przewalski's Horses in a Seminatural Habitat

Identification of the normal fluctuations in body condition of equids is important for the monitoring and management of wild and feral equid populations. Knowledge of the causative factors and implications of body condition fluctuations may allow managers to better respond with interventions when body condition fluctuations are unseasonal or extreme. The body condition score (BCS) of 33 adult Przewalski's horses (22 mares and 12 harem stallions) roaming freely in a population in excess of 300 in the Hortobágy Puszta in Hungary was assessed weekly for 12 months from January to December 2009. Mares had a higher mean BCS than stallions for each month of the year, and all horses maintained a moderate to fleshy condition score. There were two peaks and two troughs in BCS for both mares and stallions. It appears that an annual fluctuation of body condition of Przewalski's horses is normal for horses living in a semiwild habitat. This can be explained by seasonal variation in pasture quality, an energy cost to mares in late gestation and early lactation, and a large energy cost to mares and stallions in protecting new born offspring from aggressive attacks by rival stallions and the work of band stallions protecting against challenging stallions. Although there was a seasonal fluctuation in body condition, semiwild horses living in a former wild horse habitat were never in poor condition. Managers of domestic, feral, and wild horses may tolerate a small reduction in body condition of horses during the annual seasonal cycle.

Seasonal trends in the condition of nesting females of a solitary bee: wing wear, lipid content, and oocyte size.

During the nesting season, adult females of the solitary bee Megachile rotundata (F.) face considerable physical and energy demands that could include increasing wear and tear on their bodies and decreasing lipid reserves. Consequently, their reproductive performance may be affected not only by extrinsic factors (e.g., weather and floral resource availability), but intrinsic changes in their own bodies. Because of the potential fitness effects of seasonal changes in body condition, our objectives were to determine how wing wear, lipid reserves, and oocyte sizes vary during nesting seasons, beginning when females emerge as adults. As nesting progressed, females in two populations experienced a steady increase in wing wear, which is known to reduce foraging efficiency and increase risk of mortality in other bees. Soon after emergence, females exhibited sharp declines in lipid content which remained low for the remainder of the season. Newly-emerged females ingested pollen, an activity known to be correlated with the initiation of egg maturation in this species. Additionally, the early summer drop in lipid stores was correlated with an increase in the size of the oocytes carried. However, by ∼6 weeks after emergence, oocytes began to decrease in length and volume, perhaps due to nutrient deficiencies related to loss of stored lipids. Our results suggest management of M. rotundata should include rearing bees at temperatures that maximize stored lipid reserves in adults and timing bee release so that significant pollen resources are available for both adults and offspring.

Sex-Specific Seasonal Change in Body Mass in Two Species of Vespertilionid Bats

In most mammals, reproductive cost differs between males and females in timing and duration because of the different sex-specific energy allocation strategies to maximize fitness. The differences in reproductive strategy adopted by sexes may result in differences in seasonal variation of body mass. Here seasonal variations in body mass are discussed for two species of vespertilionid bats: Daubenton's bat (Myotis daubentonii) and Savi's pipistrelle (Hypsugo savii). Both species were observed to have a seasonal variability in body conditions, which was sex dependent. In late spring and for a given forearm length, females were heavier than males, but differences were small in late summer. Furthermore, female'’s body mass decreased during late spring and summer likely to support the energy requirement for lactation, while male's mass did not change (H. savii) or slightly increase (M. daubentonii) over the same period. On the contrary male M. daubentonii depleted body fat reserves during early autumn, likely because of the energy expenditure to increase mating opportunities. Our results suggest that seasonal changes in body condition in hibernating bats may reflect the differences in reproductive strategies between sexes.

Use of a modified form factor to compare condition among North American lake sturgeon stocks

Summary In fisheries management it is often useful to compare length and weight relationships or condition among populations across a species’ range. Currently, the most commonly used metric for this is relative weight (Wr), although some problems have arisen with the use of Wr including the impact of seasonal changes in body condition due to reproduction, and length-related biases in standard weight equations. We propose the use of a modified form factor (mFF) based on the regression of log10α vs β (weight–length model parameters) within a species, to provide a quick and meaningful comparison of mean condition among North American lake sturgeon populations. We used the α and β parameters from 63 lake sturgeon weight–length models from 43 lake sturgeon populations from throughout their range in the equation to calculate the mFF for the 63 samples. Modified form factor values of juvenile, adult male, and female lake sturgeon from the Winnebago System, Wisconsin, in various stages of reproductive development had a 98.0% correlation with their respective relative condition values over a wide range of mFF values. Simple t-tests on sets of mFF values can be used to test the condition differences between populations or sub-samples within populations. Lake sturgeon from the Winnebago System, Wisconsin, USA were found to show W–L relationships best described in two stanzas: all juveniles 71 cm) W–L models; juvenile (≤71 cm) and male (>71 cm) models; and juvenile (≤71 cm) and female (>71 cm) models.

Recovery of Bioenergetics Parameters from Information on Growth: Overview of an Approach Based on Statistical Analysis of Tagging and Size-At- Age Data

Parameters for size allometry in feeding and metabolic rates, along with Q10 parameters for responses of these rates to seasonal temperature change, can in principle be estimated from field data on growth, particularly seasonal tag- ging studies. However, it is still typically necessary to complement or constrain the field estimates with information from laboratory studies, particularly on power parameters for size allometry in metabolism, Q10 for metabolism, and responses of feeding rate at high temperatures. Ontogenetic habitat shifts can cause apparent changes in the size power parameters that are in fact due to temperature differences between the habitats. Seasonal changes in body condition (due to feeding, metabolism, and reproduction) can be represented using simple models for allocation of food intake to skeletal growth, though parameter estimation for such models is grossly unreliable when only seasonal changes in length growth rates have been measured.

Critical times of the year for Myotis myotis, a temperate zone bat: roles of climate and food resources

ABSTRACT In highly seasonal temperate zones climate may cause fluctuations in the accessibility of prey for insectivorous bats. The main objective of this project was to evaluate if these fluctuations can result in resource bottlenecks that affect the body condition of a temperate zone bat — Myotis myotis. Seasonal changes in body condition followed different patterns in Portugal and Germany, which have different climates. In Germany bats use thermally better hibernacula, which allow them to minimize energy expenditure, but because of the longer winters they emerge from hibernation in poorer condition. Except during the hibernation period, food was always abundant in Germany, but the condition of the animals was poor when bad weather constrained foraging, particularly in early spring. In Portugal food was limiting during the long dry summer, and this affected the condition of the animals for several months. The conclusion that food resources can act as a limiting factor is relevant for conservation becaus...

Evaluating body condition of striped skunks using non-invasive morphometric indices and bioelectrical impedance analysis

Abstract Assessment of the body composition and body condition of animals in the wild is an important aspect of animal ecology. We were interested in understanding the seasonal changes in body condition in order to investigate the effects of adaptive strategies on life histories of animals. We investigated the merit of morphometric condition indices and bioelectrical impedance analysis (BIA) to predict fat reserves in striped skunks (Mephitis mephitis, n = 26). We took BIA and morphometric measurements following chemical immobilization in the field and completed chemical analyses of whole carcasses postmortem. We determined relationships between body lipid and water using multiple linear regression techniques and performed model selection using Akaike's Information Criterion (AIC). Bioelectric volume (L2/Rs) and chest circumference (CC) best predicted total body water (TBW=–1.1+0.058*CC+0.25 * L2/Rs; r2 = 0.91, SEE=0.15, P <0.001). Lean dry mass (LDM) was significantly correlated with total body mass (LDM...

Growth and seasonal fluctuations in size and condition of male Northwest Atlantic harp seals Phoca groenlandica: an analysis using sequential growth curves

Pinnipeds have marked seasonal changes in body condition, accumulating energy re- serves prior to the reproduction period, and depleting these reserves during the breeding and molt- ing periods. This cycle is not well described in male harp seals Phoca groenlandica. We obtained mor- phometric measurements for 3167 Northwest Atlantic male harp seals sampled between 1979 and 1995. The part of the yearly cycle covered in this study (November to May) was divided into short blocks around median dates called 'periods'. For each period, a growth curve was calculated for body mass, sculp mass, core mass and standard length. These sequential growth curves were used to cal- culate changes in size-at-age between periods. In addition, seasonal changes in 3 condition indices (general, sculp and core condition), in blubber thickness and in the ratio of sculp to total mass were analyzed using locally weighted regressions. Male harp seals returned from their high-latitude feed- ing grounds heavier, in better condition, and with a thicker blubber layer than when they left the area in the spring. However, maxima in length, mass, condition and blubber thickness were not observed until the February 22 period (February 12 to March 4), or in the case of seals younger than 5 yr, some- time in March. Mass losses associated with the rut began between the periods February 22 and March 15 (March 5 to 25) and were most pronounced in seals older than 10 yr. About 66% of the losses in mass came from the core during this period. We estimated that males lost 39.4 kg during the rut (1.16 kg d -1 or 0.78% of initial mass d -1 , 44% from sculp and 56% from core) and incurred energy expenditures of 840 MJ (24.7 MJ d -1 ). This corresponds to twice the standard metabolic rate (SMR), and suggests that males are feeding during the rut. All males lost mass in April, and again in May. They began to molt April 19 period (April 16 to 22). Fewer than half the seals had completed the shed- ding of old hair when the study ended, in the May 10 period. Rates of mass loss during the molt varied from 1 to 1.8 kg d -1 , depending on the age of the seals. Minima of length, mass, condition and blubber thickness were observed in May. Molting appears to be a period of high energy expenditures (3 to 5 SMR) despite the low levels of activity observed at this time. This study revealed that length also changes seasonally: fat seals in February were longer than lean seals of the same age in late April.

Seasonal Pattern of Androgen Secretion in the Male Platypus, Ornithorhynchus anatinus, in the Upper Barnard River, New South Wales.

The seasonal pattern of androgen secretion in free-ranging male platypuses was determined in samples of peripheral blood plasma and rectal contents collected between February and November 1996, from animals captured in the Upper Barnard River, New South Wales. Cortisol concentrations in peripheral blood were also measured and seasonal changes in body condition were assessed. Androgen concentrations in samples from the different sources all followed a distinctly seasonal pattern, being low from February to June, rising in July to reach the highest values in August before reducing to lower values by September. The high concentrations occurred within a relatively narrow time frame and appeared to be well synchronised among individuals. Within animal comparisons showed that androgen concentrations in excreta were highly correlated with values for blood. Cortisol concentrations were higher in July and August than other months. Males lost body condition during this period (as indicated by changes in the Tail Volume Index) and it is suggested that they were under increased stress at this time due to rivalry between males around the mating season.

Seasonal Changes in Body Condition of White Crappies and Relations to Length and Growth in Melvern Reservoir, Kansas

Abstract Relative weights (Wr = 100 [fish weight/standard weight at length]) of white crappies Pomoxis annularis were monitored in Melvern Reservoir, Kansas, from May 1986 to November 1987 to establish size-related seasonal patterns in condition. For each month from May to November 1987, total length and monthly length increment were compared to Wr for individual fish of ages 1 and 2. Relative weights of white crappies 130–199 mm long and those 200–249 mm long both increased through spring and surpassed a mean Wr of 90 by July. After July, mean Wr for 130–199-mm fish progressively declined through fall to below 75. Mean Wr of 200–249-mm fish also declined after July, but rebounded by fall. Relative weights of white crappies 250–299 mm long decreased after spawning in May, but increased thereafter to November. Mean Wr values near 100 were maintained from November 1986 to May 1987. By the end of June, yearlings had completed 73% of their annual growth; Wr and length increment were directly related. However,...

Seasonal changes in the abundance and body condition of honeyeaters (Meliphagidae) in response to inflorescence and nectar availability in the New England National Park, New South Wales

AbstractSeasonal changes in numbers and body condition of honeyeaters were examined over 2 years in the New England National Park, New South Wales, Australia. Nectar availability measured as inflorescence density and nectar production were also recorded. In the main study site, the abundance of six of the seven most common species of honeyeater was significantly correlated with inflorescence density. However, honeyeater numbers were not significantly correlated with daily energy productivity. Unlike most honeyeater communities, the New England community was dominated numerically by the Eastern Spinebill, the smallest of the most common species present. Among the most common species, the duration of time a species was recorded in the area was negatively, but not significantly, correlated with its size. All species examined showed similar seasonal changes in body condition, with the highest bodyweights and fat deposits recorded in winter.

Water and Electrolyte Metabolism of the Tammar Wallaby Macropus eugenii

Seasonal changes in body condition and water and electrolyte metabolism in two populations of tammar wallabies (Macropus eugenii) are described in this paper. One population lives in a beach environment and has no access to freshwater, whereas the second population lives in the vicinity of a continuously flowing freshwater bore. During normal (mild) summers, the availability of free water has no influence on the condition of the tammars or on their water and electrolyte metabolism. Only during periods of extended summer drought is free water marginally advantageous to the bore population, as indicated by lower circulating antidiuretic hormone levels (ADH), a higher condition index, and lower total body water content. Both populations showed low plasma sodium concentrations after a prolonged drought, indicating that tammars are exceptionally resistant to the effects of hyponatraemia. After the onset of the winter rains, plasma sodium concentrations increase and the water turnover rises dramatically. The high water content of the vegetation at this time appears to prevent the tammars from ingesting enough food to satisfy their nutritional requirements, and their condition continues to decline, reaching its annual minimum in midwinter. It is evident that the breeding season of the tammars on Garden Island, which falls in early summer, is attuned to changes in condition and represents the only period of the year when the animals are neither water deprived nor suffering from nutritional deficiencies.

Growth, condition and reproduction in the Impala ram (Aepyceros melampus)

The relationship between reproductive activity, body growth and condition in the male Impala is examined. Body growth is described by the use of the von Bertalanffy equation, and asymptotic values for each parameter are given together with the age at which these are attained. Seasonal changes in body condition are determined by the use of the kidney index and the fat content of the bone marrow, and this is related to body weight and the time of the rut. Growth and development of the reproductive organs with age and season are described in relation to reproductive activity.