Fat Deposition and Seasonal Variation in Body Composition of Arctic Foxes in Svalbard

Prestrud, Pål; Nilssen, Kjell Tormod

doi:10.2307/3808816

Cited by 89 publications

(90 citation statements)

References 15 publications

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“…This indicates the adaptive significance of fat storing, the fat reserve in an average-sized fox in November and December approximated an energy storage of 15 640 kJ (Prestrud and Nilssen, 1992), enough energy to survive for : 19 days without food at RMR levels. Thus, the arctic fox may be capable of enduring long periods of starvation, especially in winter when food is scarce.…”

Section: Introductionmentioning

confidence: 83%

“…Seasonal variations in body fattening (Prestrud and Nilssen, 1992) and body weight (Fuglei and Øritsland, 1999a) have been reported in arctic foxes on Svalbard, with the highest levels of body fat in November and December (20%) and lowest in June and July (6%). This indicates the adaptive significance of fat storing, the fat reserve in an average-sized fox in November and December approximated an energy storage of 15 640 kJ (Prestrud and Nilssen, 1992), enough energy to survive for : 19 days without food at RMR levels.…”

Section: Introductionmentioning

confidence: 95%

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Hormones and metabolites of arctic foxes (Alopex lagopus) in response to season, starvation and re-feeding

Fuglei

Aanestad

Berg

2000

Comparative Biochemistry and Physiology Part A: Molecular &

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Svalbard's arctic foxes experience large seasonal variations in light, temperature and food supply throughout the year, which may result in periods of starvation. The aim of this work is to investigate if there are seasonal variations in post-absorptive plasma thyroid hormones (free thyroxin (fT 4 ), free triiodothyronine (fT 3 ) and reverse triiodothyronine (rT 3 )) and metabolites (free fatty-acids (FFA) and b-hydroxybutyrate (b-OHB)) with season and their response to starvation and re-feeding. The concentrations of post-absorptive free triiodothyronine were significantly higher in November than May, while those of thyroxin, reverse triiodothyronine, free fatty-acids and b-hydroxybutyrate remained unchanged. Possible explanations for the seasonal variations in free triiodothyronine are discussed. There were no significant changes from post-absorptive concentrations of thyroxin and reverse triiodothyronine in starved and re-fed foxes. However, free triiodothyronine concentrations decreased during starvation and increased again with re-feeding both in May and November. Starvation induced high levels of free fatty acids in both May and November, indicating increased lipolysis. There was a significant increase in b-hydroxybutyrate in November only, indicating that arctic foxes are capable of protein conservation during starvation.

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 95%

Hormones and metabolites of arctic foxes (Alopex lagopus) in response to season, starvation and re-feeding

Fuglei

Aanestad

Berg

2000

Comparative Biochemistry and Physiology Part A: Molecular &

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“…However, the seasonal cycles in body fat reserves and body weight do not only depend on changes in food availability. Previous studies have found a seasonal variation in body mass of ad libitum-fed arctic foxes in captivity with the lowest body mass in the summer season and the highest in winter (Haga 1993;Korhonen and Alasuutari 1995;Fuglei and Øritsland 1999), which probably reflects the normal pattern of fat deposition observed in these species (Prestrud and Nilssen 1992). Wild arctic foxes kept in captivity on Svalbard also showed seasonal variation in resting metabolic rate (RMR), with the lowest values in October-December and the highest in May-July (Fuglei and Øritsland 1999).…”

Section: Introductionmentioning

confidence: 84%

“…Many foxes are in good body condition, while others have depleted almost all visible fat (E. Fuglei, personal communication). This indicates periods (days-weeks) of fasting due to food shortage during winter (Prestrud and Nilssen 1992;Fuglei and Øritsland 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Deposition of subcutaneous and visceral fat takes place in August-September reaching a maximum in NovemberDecember, when the body lipid stores may constitute more than 20% of the total body weight. Body fat is rapidly mobilised from March through May and is lowest in June-July (6%; Prestrud and Nilssen 1992). However, autopsies of arctic fox carcasses trapped between November and March show large individual variations in subcutaneous and visceral fat.…”

Section: Introductionmentioning

confidence: 99%

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Effects of season, food deprivation and re-feeding on leptin, ghrelin and growth hormone in arctic foxes ( Alopex lagopus ) on Svalbard, Norway

Fuglei

Mustonen

Nieminen

2004

Journal of Comparative Physiology B: Biochemical, Systemic, and

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The arctic fox (Alopex lagopus) is a mediumsized predator of the high Arctic experiencing extreme seasonal fluctuations in food availability, photoperiod and temperature. In this study, the plasma leptin, ghrelin and growth hormone (GH) concentrations of male arctic foxes were determined during a food deprivation period of 13 days and the subsequent recovery in November and May. Leptin, ghrelin and GH were present in arctic fox plasma in amounts comparable to other carnivores. The plasma leptin concentrations did not react to food deprivation unlike in humans and rodents. However, the leptin levels increased during re-feeding as an indicator of increasing energy reserves. The relatively high ghrelin-leptin ratio, decrease in the plasma ghrelin concentration, an increase in the circulating GH concentrations and the observed negative correlation between plasma ghrelin and free fatty acid levels during fasting suggest that these hormones take part in the weight-regulation and energy metabolism of this species by increasing fat utilisation during food deprivation. The results strengthen the hypothesis that the actions of these weight-regulatory hormones are species-specific and depend on seasonality and the life history of the animals.

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Comparative transcriptome provides insights into the selection adaptation between wild and farmed foxes

Yang

Liu

Wang

et al. 2021

Ecology and Evolution

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Fat Deposition and Seasonal Variation in Body Composition of Arctic Foxes in Svalbard

Cited by 89 publications

References 15 publications

Hormones and metabolites of arctic foxes (Alopex lagopus) in response to season, starvation and re-feeding

Hormones and metabolites of arctic foxes (Alopex lagopus) in response to season, starvation and re-feeding

Effects of season, food deprivation and re-feeding on leptin, ghrelin and growth hormone in arctic foxes ( Alopex lagopus ) on Svalbard, Norway

Comparative transcriptome provides insights into the selection adaptation between wild and farmed foxes

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