Harsh climate selects for small body size among Iceland's Arctic foxes

Yom‐Tov, Yoram; Hersteinsson, Páll; Yom‐Tov, Elad

doi:10.1111/ecog.01782

Cited by 3 publications

(6 citation statements)

References 33 publications

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“…The 1‐year‐old data reflect the dietary experience foxes went through in their first year of life including their first winter when they would have reached independence, thus controlling for the effect of age. Temperature, SPG (ψv) , and other climatic variables also influence population size, body fat, and morphometrics of arctic foxes in Iceland (Hersteinsson et al, 2009; Pálsson et al, 2016; Yom‐Tov et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…To test the effect of the environment on tooth breakage and wear we compiled data for four key environmental predictors which were shown to have a significant effect on the morphology and survival of arctic foxes and on the population size of avian prey (Hersteinsson et al, 2009; Yom‐Tov et al, 2017). The first predictor was annual winter temperature, defined as the mean temperature during December–February at each of the three subregions in Iceland.…”

Section: Methodsmentioning

confidence: 99%

“…We used the extensive collection of arctic fox lower mandibles (over 12,000 specimens), collected initially by the late Pall Hersteinsson and later by E.R.U., and now stored in the Icelandic Institute of Natural History (Carbonell Ellgutter et al, 2020; Hersteinsson et al, 2009; Yom‐Tov et al, 2017). This collection is derived from arctic fox carcasses that were voluntarily supplied by fox‐hunters for the last 40 years, who also provided specific information on the date and collection locality of every individual.…”

Section: Methodsmentioning

confidence: 99%

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Sub‐zero temperatures and large‐scale weather patterns induce tooth damage in Icelandic arctic foxes

Roemer

Unnsteinsdóttir

Valkenburgh

2023

Global Change Biology

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Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carnivores, it is associated with increased bone consumption. Variation in tooth condition in Icelandic arctic foxes, a mesocarnivore, was recorded from 854 individual foxes spanning 29 years. We hypothesized that annual climatic variations, which can influence food abundance and accessibility, will influence tooth condition by causing dietary shifts toward less edible prey. We examined tooth condition in relation to four climatic predictors: mean annual winter temperature, indices of both the El Niño anomaly and North Atlantic subpolar gyre (SPG), and the number of rain‐on‐snow days (ROS). We found unequivocal evidence for a strong effect of annual climate on tooth condition. Teeth of Icelandic foxes were in better condition when winter temperatures were higher, when the SPG was more positive, and when the number of ROS was low. We also found a substantial subregional effect with foxes from northeastern Iceland having lower tooth damage than those from two western sites. Contradicting our original hypothesis that foxes from northeastern Iceland, where foxes are known to scavenge on large mammal remains (e.g., sheep and horses), would show the highest tooth damage, we suggest that western coastal sites exhibited greater tooth damage because cold winter temperatures lowered the availability of seabirds, causing a shift in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack. Our study shows that monitoring tooth breakage and wear can be a useful tool for evaluating the impact of climate on carnivore populations and that climate change may influence the condition and fitness of carnivores in complex and potentially conflicting ways.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Sub‐zero temperatures and large‐scale weather patterns induce tooth damage in Icelandic arctic foxes

Roemer

Unnsteinsdóttir

Valkenburgh

2023

Global Change Biology

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“…The subpolar gyre affects flow of nutrients within the ocean, including phosphate, nitrate and silicates (Hátún et al, 2017(Hátún et al, , 2016Johnson, Inall, & Häkkinen, 2013). SPG-I is highly correlated to body size and body mass in Icelandic arctic foxes (Vulpes lagopus), presumably because the SPG-regulated ocean forces affect food availability to the foxes, particularly in coastal habitats in west Iceland where seabirds are an important part of the fox's diet (Yom-Tov, Hersteinsson, Yom-Tov, & Geffen, 2017).…”

Section: Introductionmentioning

confidence: 99%

Numbers and distribution of the Great Cormorant in Iceland: Limitation at the regional and metapopulation level

Gardarsson

Jónsson

2019

Ecology and Evolution

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We studied a metapopulation of great cormorant (Phalacrocorax carbo) in Iceland, using complete aerial censuses of nests in 25 years during 1975–2015. Age composition was estimated in 1998–2014 by ground surveys in September and February. Brood size was estimated from aerial photographs in 2007–2015. Weather, food, breeding habitat, and density were considered as explanatory variables when examining numerical and distributional changes in the cormorant metapopulation. In 1975–1990 total nest numbers changed little, very low numbers about 1992 were followed by an annual increase of 3.5% in 1994–2015. Total nest numbers were positively correlated with estimates of spawning stocks of cod and saithe and inversely related to the subpolar gyre index (SPG‐I). During the increase in 1994–2015, average colony size at first increased and then declined. Habitat use also changed: the proportion of nests on small rocky islets (skerries) at first declined, from 69% to 44% in 1995–2003 and then increased again to about 58% in 2012–2014. Habitat changes were probably a response to changed patterns of human disturbance. Breeding density, as nests per km 2 sea <20 m deep, was rather uniform among five defined regions in 1975–1996. Thereafter, densities became much higher in two sheltered regions with kelp forests and in one mostly exposed region. A second exposed region remained low and in the third nest numbers declined markedly. Thus, carrying capacity was higher in sheltered regions where cormorant breeding had historically been depressed by human disturbance. Brood size varied little among regions but declined with the years from about 2.5 to 1.8. The proportion of juveniles in September (fecundity) declined in 1998–2015 from over 0.4 to 0.3 and was inversely correlated with year and nest numbers, if outlier years were excluded, suggesting resource limitation. Survival of juvenile cormorants in September–February was estimated at 0.471 ± 0.066 SE . Commercial fish stocks and climate indices were not correlated with the proportion of juveniles. Annual survival of adults (breeding and nonbreeding) was estimated from nest counts and age composition 1999–2014, as 0.850 ± 0.026 SE and showed no trend in 1998–2014. We conclude that the metapopulation of cormorants in Iceland was resource‐limited at two levels: fecundity at the regional and winter survival at the total level.

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“…These centre on: thermoregulatory response (Bergmann 1847;James 1970;Speakman & Kr ol 2010); primary productivity (food availability) (Rosenzweig 1968;Wigginton & Dobson 1999;McNab 2010); evolutionarily relevant Net Primary Productivity (eNPP) (food availability that is regulated by the NPP of plants during the growing season) , 2011; and seasonality (Lindsey 1966). Of these hypotheses, primary productivity has received most support as the primary predictor of spatial body-size variation in numerous species of mammals (Rosenzweig 1968;Kolb 1978;Yom-Tov & Nix 1986;Yom-Tov & Geffen 2006;Blois et al 2007;G€ ur 2010;G€ ur & G€ ur 2012;Alhajeri & Steppan 2016;Correll et al 2016;Schiaffini 2016;Yom-Tov et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Environmentally‐ and human‐induced body‐size responses in Macropus robustus and Macropus rufus, two widespread kangaroo species with largely overlapping distributions

2017

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Progressive body-size dwarfing of animal populations is predicted under chronic mortality stress, such as that inflicted by human harvesting. However, empirical support for such declines in body size due to elevated mortality is lacking. In fact, the size of three macropodid species ─ the two grey kangaroo species, Macropus fuliginosus and M. giganteus, and the Red-necked Wallaby, M. rufogriseus ─ appears to have increased since European settlement in Australia, despite these species being subjected to size-selective harvesting over this period. To test whether this unexpected trend also characterises other species, we sought evidence of humaninduced body-size changes in the two most widely distributed kangaroo species, the Euro Macropus robustus and Red Kangaroo M. rufus, from the late 19th Century onwards. Spatial autoregressive models controlling for age, sex and island effects were first used to identify environmental predictors of body size and to evaluate multi-causal explanations for spatial body-size patterns. Primary productivity emerged as the key driver of body size in both species, while heat conservation was supported as a further mechanism explaining the large body size of M. robustus in cold climatic regions. After controlling for these environmental factors, we find that the size of M. rufus has been stable over time and limited support for a small increase in the size of M. robustus. Hence, there is no empirical evidence that contemporary size-selective harvesting has reduced body size in these species. Rather, the latter result supports the possibility that pasture improvement and/or dingo control (and associated reduction in predation pressure) facilitated body-size increases following European settlement in Australia.

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Harsh climate selects for small body size among Iceland's Arctic foxes

Cited by 3 publications

References 33 publications

Sub‐zero temperatures and large‐scale weather patterns induce tooth damage in Icelandic arctic foxes

Sub‐zero temperatures and large‐scale weather patterns induce tooth damage in Icelandic arctic foxes

Numbers and distribution of the Great Cormorant in Iceland: Limitation at the regional and metapopulation level

Environmentally‐ and human‐induced body‐size responses in Macropus robustus and Macropus rufus, two widespread kangaroo species with largely overlapping distributions

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