Variability in body mass and sexual dimorphism in Danish red foxes (<i>Vulpes vulpes</i>) in relation to population density

Pagh, Sussie; Hansen, Mette Sif; Jensen, Birger; Pertoldi, Cino; Chriél, Mariann

doi:10.1080/21658005.2017.1409997

Cited by 6 publications

(7 citation statements)

References 31 publications

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“…The increase in stone marten density in this region might have increased intraspecific competition that could have caused a body mass decrease over time. Such a decrease of body mass, during a period of population establishment and demographic expansion, was observed in American mink ( Neovison vison ) and red fox ( Vulpes vulpes ) in Europe 63 , 64 . Stone marten body size also decreased on the southern Iberian Peninsula, but the mechanism driving this change is unclear.…”

Section: Discussionmentioning

confidence: 91%

Different increase rate in body mass of two marten species due to climate warming potentially reinforces interspecific competition

Wereszczuk

Hofmeester

Csanády

et al. 2021

Sci Rep

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Many species show spatial variation in body size, often associated with climatic patterns. Studying species with contrasting geographical patterns related to climate might help elucidate the role of different drivers. We analysed changes in the body mass of two sympatric medium-sized carnivores—pine marten (Martes martes) and stone marten (Martes foina)—across Europe over 59 years. The body mass of pine marten increased with decreasing latitude, whereas stone marten body mass varied in a more complex pattern across its geographic range. Over time, the average body mass of pine martens increased by 255 g (24%), while stone marten by 86 g (6%). The greatest increase of body mass along both martens’ geographic range was observed in central and southern Europe, where both species occur in sympatry. The body mass increase slowed down over time, especially in allopatric regions. The average pine/stone marten body mass ratio increased from 0.87 in 1960 to 0.99 in 2019, potentially strengthening the competition between them. Thus, a differential response in body size to several drivers over time might have led to an adaptive advantage for pine martens. This highlights the importance of considering different responses among interacting species when studying animal adaptation to climate change.

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Section: Discussionmentioning

confidence: 91%

Different increase rate in body mass of two marten species due to climate warming potentially reinforces interspecific competition

Wereszczuk

Hofmeester

Csanády

et al. 2021

Sci Rep

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“…An increasing number of papers support the hypotheses that geographic variation in body size within a species is caused by local or temporal variation in food supply (e.g. [28–33]. Basically, there are two ways that food influences the body size of fully grown individuals.…”

Section: Discussionmentioning

confidence: 99%

“…First, ample nutrition during the individual’s development is essential in obtaining optimal body weight. In free ranging populations, variation in food supply from year to year is known to produce cohorts of generations with different mean body weight caused by yearly fluctuations in food supply [33–35]. Secondly, the fully grown body size of an individual may genetically be adapted to “bottleneck” periods, e.g.…”

Section: Discussionmentioning

confidence: 99%

Methods for the identification of farm escapees in feral mink (Neovison vison) populations

et al. 2019

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In Denmark, American mink (Neovison vison) have been bred for their fur since the mid-1920s. Mink escaping from farms may supply the feral population. Often, it is of biological and management interest to separate the population of feral mink (i.e. mink caught in the wild) in two groups: 1) mink born on farms i.e., escapees, and 2) mink born in the wild. In this study, two methods were used for separating feral mink into the two groups: a) Comparison of body length of farmed mink and feral mink, and b) Presence of a biomarker (tetracycline: an oral antibiotic used on mink farms). A total of 367 wild caught mink (from the mainland of Denmark and the island of Bornholm), and 147 mink from farms, collected during the period 2014–2018, were used for the analysis of body length. For the testing of tetracycline (TC) as a biomarker, 78 mink from farms where there was knowledge about TC treatment (with or without) were examined for fluorescent markings in the canine teeth. Results from both univariate analyses and Gaussian mixture model analysis demonstrated clear divisions between the mean body length (mean ± S.E., range) of farmed males (52.1 cm ± 0.4, 48–68) and farmed females (mean 44.0 ± 0.2, 40–50), and between farmed mink and wild caught mink. Mixture analysis identified two groups within each sex of the wild caught mink, one assigned to farmed mink (born in captivity) and another group of smaller mink suspected of being born in the wild. On Bornholm, the mean (±SD, range) length of males born in the wild was 43.7cm (± 0.3, 36–57) and for females 37.5cm (± 0.3, 32–45). The mean length (±SD, range) of males born in the wild in the mainland of Denmark was 42.5cm (± 2.3, 36–46) and for females 36.1cm (± 1.0, 34–37). Among the feral mink from mainland Denmark, 28.4% of males and 21.6% of females were identified as escapees, while 0% of the males and 1% of the females were identified as escapees among the wild caught mink on Bornholm. Eight percent of mink from farms using tetracycline were false negatives, while no false positives were found among mink from farms not using TC. TC fluorescence was found in five of 217 mink caught in the wild equivalent to 22% escapees in mainland Denmark. No TC markings were found in mink caught in the wild on Bornholm. In conclusion, both methods a) the body length of mink, and b) fluorescent biomarkers in canine teeth are considered as useful tools to identifing mink that have escaped from farms.

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“…Studies of the size of adult red foxes (Vulpes vulpes) show that SSD is male biased and that average SSD ranges between 4.4% and 7.7% in Europe and North America and that SSD may not only vary geographically, but also locally during different time periods (Cavallini, 1995;Pagh et al, 2017).…”

Section: Ontogeny Of Ssd In Mammalsmentioning

confidence: 99%

“…Although individual foxes most likely stop growing at maturity, a study of Danish foxes showed that older foxes are heavier (Pagh et al 2017). This is most probably be due to selection for larger foxes, although it cannot be ruled out, that foxes may grow after one year, or that older foxes are more experienced hunters (Iossa et al, 2008;Pagh et al, 2017).…”

Section: Bimaturism or Selection For Larger Foxes?mentioning

confidence: 99%

Development of Body Mass and Sexual Size Dimorphism in Danish Red Foxes (Vulpes Vulpes)

Pagh

Chriél

Jensen³

et al. 2018

GABJ

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In this study, we examine the development of body mass and sexual size dimorphism (SSD) in 178 juvenile wild Danish red foxes from 99 litters using piecewise analyses of regression lines for age versus weight. When fox cubs are younger than 100 days, only slight (SSD=1.7%) and no significant difference (t-test: t=1.2, p=0.24) was found in the mean weight of males (2.03± kg) and females (1.93± kg), and no significant difference was found in the slope of regression lines for males and females (F=0.97E-5, p = 0.99). In the growth period between 100 days of age and mating around 275 days of age, the regression line in males steepens more than that of females (difference in slopes, F=5.9, p<0.02) and the difference in mean weight of the sexes become highly significant (SSD=7.4%, difference in mean t=4.6, p=2.2E-5). After mating the growth curve levels off i.e. the slope of the regression lines for age versus weight is not significantly different from zero. Yearly variation was revealed in the growth rate of juvenile foxes (difference in slope for males; F=3.9, p<0.01 and females; F=8.6, p<0.001). Conclusion: SSD in red foxes mainly develop as a result of a faster grow rate in males between indepency and maturity. Ontogony of red foxes may genetically be disposed to prevent males outcompeting females in the early stages of life (<100 days), when cubs are still fed by adults and the increase in SSD before mating, may be an adaption to selective forces benefitting larger males. The growth rate of juvenile foxes of both sexes is influenced by environmental variation in different years.

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Variability in body mass and sexual dimorphism in Danish red foxes (Vulpes vulpes) in relation to population density

Cited by 6 publications

References 31 publications

Different increase rate in body mass of two marten species due to climate warming potentially reinforces interspecific competition

Different increase rate in body mass of two marten species due to climate warming potentially reinforces interspecific competition

Methods for the identification of farm escapees in feral mink (Neovison vison) populations

Development of Body Mass and Sexual Size Dimorphism in Danish Red Foxes (Vulpes Vulpes)

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