Temporal and geographical variation in skull size of the red fox (Vulpes vulpes) and the Eurasian badger (Meles meles) in Austria

Using museum material, we studied temporal changes in skull size of 185 red foxes (Vulpes vulpes Linnaeus, 1758) and 71 Eurasian badgers (Meles meles Linnaeus, 1758) collected in Austria between 1866 and 2007. Four measurements were taken and combined into principal components by means of a principal components analysis. Akaike's information criterion models indicated that skull size of the red fox and the Eurasian badger is positively related to the year of collection and negatively to altitude but not to latitude or longitude. However, for the Eurasian badger, the relationship between skull size and year is only on the verge of significance. We suggest that the increase in skull size with year is a result of improved food availability during the 20th Century from man‐made resources such as agricultural produce and garbage, and the decrease in skull size with altitude is possibly the result of a parallel decrease in primary productivity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Body size of the red fox Vulpes vulpes in Spain: the effect of agriculture

The body size of animals is affected by several factors, including ambient temperature and food availability. Ambient temperature is often negatively related to body size (Bergmann's rule) whereas an improved diet, especially during growth, has a positive effect. Animals commensal with man commonly exploit additional food sources (e.g. garbage dumps), thereby increasing their food supply. Using museum material, we studied morphological variation in skull size (and thus body size) among Spanish red foxes. Four measurements were taken of each skull and were related to the habitat from which the foxes were collected (agricultural and non-agricultural), and to latitude as a proxy for ambient temperature. The skull size of foxes collected in agricultural areas during the late 20th Century was significantly larger than that of those from non-agricultural areas, and was negatively related to latitude, thus contradicting Bergmann's rule. We suggest that increased food availability from animal husbandry is the cause for the observed increase in skull size (and thus body size).  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 729–734.     

Recent increase in body size of the American marten Martes americana in Alaska

Using museum specimens, we studied recent changes in skull size of the American marten Martes americana , in continental Alaska. In Alaska, global warming has resulted in milder winters that may contribute to an improved food supply in the wild. In the present study, we tested the hypothesis that body size of the marten had increased during the second half of the 20th century, in response to global warming. We found that skull size, and by implication body size, increased significantly during the second half of the 20th century, possibly due to an improved food supply and/or lower metabolic demands in winter. Improved food availability in winter may result from the improved nutritional conditions for prey, and/or from increased access to prey resulting from a longer snow-free season. Longitude had a significant positive effect on skull size and a significant negative effect on teeth size. In Alaska, the climate is milder along the western coast and becomes harsher inland. Hence, the milder climate was associated with larger body size providing further support for our prediction that body size of the American marten was influenced by food availability and reduced energy expenditure. The negative relationship between longitude and teeth size may indicate a trend towards a larger prey in inland marten populations, but we have no data to support or refute this hypothesis.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 701–707.     

Population cycles and changes in body size of the lynx in Alaska

The lynx Lynx canadensis is a common predator in the boreal forests of North America. Its population fluctuates during a 9- to 11-year cycle in synchrony with the population size of its main prey, the snowshoe hare Lepus americanus. Using adult museum specimens, we studied changes in skull (and hence body) size of the lynx in Alaska during the second half of the 20th century. The population cycle in Alaska averaged 9 years, similar to that reported in the neighbouring Yukon. Using harvest data of lynx as an estimate of population size, we found that skull size was negatively related to population size. This relationship was strongest not for the population density in the year of death (X), but for year X-3, a carry-over effect from the first year (or years) of life, indicating that conditions during the fast-growth years are determining body size. We suggest that the density-dependent effect is probably due to changes in food supply, either resulting from the adverse effects of competition or a possible diminished availability of food. Two skull parameters decreased significantly during the second half of the 20th century. We do not know the cause for the year effect and suggest that it might be due to a long-term change in the availability of prey. Canine size did not change during the study period, probably an indication that snowshoe hares maintained their status as the main prey of the lynx throughout the study period. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Length–weight and length–length relationships for 10 pelagic fish species from the Adriatic Sea (Croatia)

Length–weight and length–length relationships are described for 10 of the most important and most frequent small, middle‐size and large pelagic fish species from the Adriatic Sea, namely Sardina pilchardus Walbaum 1792, Sardinella aurita Valenciennes 1847, Sprattus sprattus Linnaeus 1758, Engraulis encrasicolus Linnaeus 1758, Belone belone Linnaeus 1761, Scomber scombrus Linnaeus 1758, Scomber japonicus Houttuyn 1780, Thunnus thynnus Linnaeus 1758, Auxis rochei Risso 1810 and Sarda sarda Bloch 1793. Length–length equations for converting size measurements: standard length (SL) and fork length (FL) to total length (TL) and vice versa, were linear.     

Decrease in body size of Danish goshawks during the twentieth century

Recent studies indicated that body size of various animals, including birds, changed during the twentieth century, and these changes were attributed to changes in food availability and climate. We used museum skins of goshawks (Accipiter gentilis) collected between 1854 and 1941 and between 1979 and 1998 in order to check whether body size of this species in Denmark changed during the study period. We compared three body measurements (wing, beak and tarsus length) and the first principal component (PC1) derived from these measurements of four groups of goshawks (adult and immature, females and males). We found that the wing length of goshawks collected after 1979 was significantly smaller in comparison with those collected before this year, and females were more affected than males. Immature birds (but not adults) collected after 1979 had significantly shorter beaks than those from the early period. Immature females collected after 1979 had shorter tarsi than those collected in the early period. There was a significant decrease in body size (as represented by PC1) from the early to late period, which was more pronounced among females and immature birds. In conclusion, body size of goshawks in Denmark decreased during the twentieth century.     

Temperature trends and recent decline in body size of the stone marten Martes foina in Denmark

We studied a sample of 131 skulls of the stone marten Martes foina that were collected in Denmark between 1858 and 1999. Data were available for 37 years, but collection effort was not uniform throughout the study period and annual sample size varied between 1 and 27. We used principal component analysis (PCA) to combine the information of four skull measurements into a single variable (PC1). PC1 was then corrected for factors that significantly affected it (sex and longitude), and residual PC1 was used for further analysis in which we calculated trends in PC1 values during the study period. During the study period there was an increase in mean annual temperature in Denmark, but this increase was not continuous, as there was slight decrease in temperature between 1947 and 1965.We found that skull size (and by implication body size) of the stone marten in Denmark had two periods of decrease and these two periods coincide with the periods of increase in mean annual temperature. These results may indicate that body size of the stone marten is sensitive to the change in ambient temperature, either due to a change in food availability that was caused by the increase in temperature, or decreased its size in accordance with Bergmann's rule.     

Food habits, ontogenetic diet shift and selectivity in Zeus faber Linnaeus, 1758

The feeding habits of Zeus faber Linnaeus, 1758 were studied by examining digestive tracts in I2 size classes of individuals. It is a stenophagus species which begins life feeding almost exclusively on zooplankton until it is about 80 mm long, then switches gradually from zooplankton to small demersal fish, and finally when > 140 mm switches to feeding exclusively on benthic and demersal fish. Mysids were the most important food component in Z.faber < 141 mm and Cepola macrophthalma (Linnaeus, 1758) in Z.fiber > 140mm. The switch to fish prey was followed by a greater body weight per unit length. Z.faber > 140 mm selected primarily for small-and intermediate-sized C. macrophthalma (and to a lesser extent for Callionymus maculatus Rafinesque-Schmaltz, 1810, Gaidropsarus sp. and Trigla Iyra Linnaeus, 1758). Our results suggested that the ratio of vertical to horizontal dimension of prey, the motion and coloration of prey as well as the visual capabilities and perceptual potentialities of Z. faber may all in a synergetic fashion account for prey type and size selection and the positive relations found between the size of Z.faber and the size and variance of its ingested prey. Possible co-evolutionary relationships between Z.faber and C. macrophthalma are also discussed.     

The body size of wild boar during the Mesolithic in southern Scandinavia

In order to study the body size of wild boarSus scrofa Linnaeus, 1758 during the Boreal and Atlantic Chronozones in southern Scandinavia, 12 measurements of teeth and bones from 32 Mesolithic sites from Scania (Sweden) and Zealand and Jutland (Denmark) were analysed. The osteometric analysis revealed that the body size of wild boar from Scania did not change during the period. The results indicate that the changes of ecological conditions during the transition from the Boreal to the Atlantic chronozones did not affect wild boar in the same way as red deer and roe deer, which decreased in body size during the period. The tooth size of wild boar from Zealand is smaller than in wild boar from Jutland and Scania during the Late Atlantic Chronozones, which probably is the result of the isolation of the population when Zealand became an island. Calculations of withers height show that wild boar in southern Scandinavia during the Atlantic Chronozones were of similar body size as recent wild boar from eastern Europe.     

Oyster (Ostrea edulis) extirpation and ecosystem transformation in the Firth of Forth,Scotland

Marine inshore communities, including biogenic habitats have undergone dramatic changes as a result of exploitation, pollution, land-use changes and introduced species. The Firth of Forth on the east coast of Scotland was once home to the most important oyster (Ostrea edulis Linnaeus, 1758) beds in Scotland. 19th and early 20th century fisheries scientists documented the degradation and loss of these beds, yet transformation of the wider benthic community has been little studied. We undertook archival searches, ecological surveys and shell community analysis using radioisotope dated sediment cores to investigate the history of decline of Forth oyster beds over the last 200 years and the changes to its wider biological communities. Quadrat analysis of the present day benthos reveal that soft-sediment communities dominate the Firth of Forth, with little remaining evidence of past oyster beds in places where abundant shell remains were picked up by a survey undertaken in 1895. Queen scallops (Aequipecten opercularis Linnaeus, 1758) and horse mussels (Modiolus modiolus Linnaeus, 1758) were once common within the Forth but have also markedly decreased compared to the earlier survey. Ouranalyses of shell remains suggest that overall mollusc biomass and species richness declined throughout the 19th century and early 20th century, suggesting broader-scale community change as human impacts increased and as habitats degraded. Inshore communities in the Firth of Forth today are less productive and less diverse compared to past states, with evidence suggesting that most of the damage was done by early bottom trawling and dredging activities. Given the pervasive nature of intensive trawling over the past 150 years, the kind of degradation we document for the Firth of Forth is likely to be commonplace within UK inshore communities.     

Behavioural and spatial adaptation of the Eurasian lynx to a decline in prey availability

The distribution and abundance of food resources is a major factor influencing animal populations. I studied the effect of a roe and red deer population decline on diet composition, home range size and foraging pattern in the Eurasian lynxLynx lynx (Linnaeus, 1758) in the Bia?owie?a Primeval Forest (BPF), eastern Poland. The population of cervids in BPF experienced a nearly two-fold reduction in size from 1991 through 2006 due to severe hunting pressure between 1991 and 1996. Comparison of published data on lynx diet during the high abundance of ungulates with new data obtained for the low abundance period showed that despite a significant decline in their availability, cervids (roe and red deer) continued to form the majority of the diet of lynx, with roe deer being most preferred in both periods. Home range sizes of lynx showed a tendency to increase with declining prey densities, as indicated by relative percentage increases in average yearly home range sizes amongst different sex/age groups. In response to lower availability of their main prey, lynx increased their daily straight-line movement distances by 44% and doubled the ranges covered in 5-day periods. This illustrated that, with declining prey abundance, the lynx increased their hunting efforts by either spending more time actively searching for prey or continuing foraging even after a successful hunt. Spatial analysis of the distribution of ungulates and lynx indicated that deer were evenly distributed throughout lynx ranges in BPF and spatial proximity of the predator to prey sites did not play an important role in the efficiency of hunting. Lynx may adapt to changing prey availability by increasing search effort, but this was not sufficient to prevent the negative influences of the prey decline on the lynx population. Prey depletion has an immediate effect on lynx spatial organization and, in consequence, on their density. This information has to be considered in prioritizing lynx conservation measures and management of ungulates.     

Morphometric variation of the skull during postnatal development in the Lowland European bisonBison bonasus bonasus

We studied the variation of linear measurements and skull capacity in Lowland European bisonBison bonasus bonasus (Linnaeus, 1758) during postnatal development, and the dependencies of the parameters in relation to sex, age, and body mass of the animals. Material consisted of 599 bison skulls (310 males and 289 females), within the age range of 1 month to 21 years (males) and to 27 years (females). In the group of calves to 1 year old, no sex connected differences in skull measurements were observed, whereas the skull capacity in older calves was significantly larger (0.01>p>0.001) in males than in females. From the third year of life, most skull measurements display characteristics of sexual dimorphism. Skull development in both sexes is most intensive during the first three years of life, and slows from the age of 5. In older individuals of both sexes (≥ 6 years), orbital breadth continues growing and, in females, breadth of splanchnocranium continues increasing. Growth in a bison’s skull capacity is most intensive up to the third year of life and slows from the age of 5. During postnatal development, a bison skull grows proportionally except the neurocranium, which grows slightly slower in comparison with basal length and its development finishes earlier than that of splanchnocranium. In ontogenesis, a bison skull grows much slower compared to body mass. In relation to body mass, skull capacity and the height of neurocranium grow most slowly while orbital breadth grows most intensively. The results obtained were compared with data on skull sizes of bison born in 1930–1950 and bred in captivity and with skulls of the American bisonBison bison. Inbreeding is probably responsible for some types of phenotypic abnormalities in the skull which appear in modern European bison.     

Did the historical range of the European bison (<Emphasis Type="Italic">Bison bonasus</Emphasis> L.) extend further south?—a new finding from the Yenikapı Metro and Marmaray excavation,Turkey

The origin of the European bison (Bison bonasus, Linnaeus, 1758) has been widely discussed and investigated in recent years. The species had a wide historic geographic distribution throughout the European continent during the middle and late Holocene, ranging from France in the west to the Caucasus in the east. However, archaeological evidence is needed to resolve the southern extent of the European bison distribution. We discovered one bison skull fragment during archaeological excavations in 2008 in the area of Yenikap? Metro and Marmaray (Turkey). Radiocarbon dating indicated the skull was deposited during the Byzantine period (seventh to eighth century AD). Mitochondrial genome analyses provided clear evidence that the skull was from a European bison. This is the first unambiguous evidence of the presence of this species in southeastern Europe during Byzantine times, which validates the historical written records of a potentially wider range of the European bison in historical times.     

Why are shrews so small? The costs and benefits of small size in northern temperateSorex species in the context of foraging habits and prey supply

This paper reviews the ecological advantages and disadvantages of very small body size inSorex Linnaeus, 1758 shrews living at high latitudes with cold winters. It examines the feeding and foraging habits of small and large shrews in the context of prey supply, location of winter prey sources, territory requirements, habitat exploitation and inter-specific competition. Data on feeding habits and prey availability show that the major costs of small size are a reduction in food niche breadth and prey biomass resulting from restrictions on the type and size of prey eaten, and large territory requirements. Major benefits of small size are the ability to subsist on small, numerous and accessible arthropods with high encounter rates, enabling coexistence with larger congeners and exploitation of low-productivity habitats less suitable for larger earthworm-eating species. Small size, coupled with low per capita food intake, is shown to be of special adaptive value in cold winters when food supply is restricted mostly to small arthropods, and earthworms are few.     

Climatic change and body size in two species of Japanese rodents

Using museum specimens, we studied temporal changes in skull size in two species of Japanese rodents, the large Japanese field mouse ( Apodemus speciosus ) and Pratt's vole ( Eothenomys smithii  =  E. kageus ) during the 20th century. We used the greatest length of the skull (GTL), zygomatic breadth (ZB), narrowest width of the skull across the interorbital region (IC) and the length of the upper cheek teeth row (M) as indicators to such changes. We found that GTL and ZB (but not IC and M) increased during the study period in mice, and that IC and M (but not GTL and ZB) increased marginally in voles. We attribute these changes to elevated ambient minimal temperatures, which increased food availability and energy savings for the mice, and required diet change in the voles.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 263–267.     

Body size and craniometry of the herb field mouse from Lithuania in the context of species range

We present morphometric and craniometric measurements of the herb field mouse (Apodemus uralensis) from Lithuania and analyze variation of body and skull size across species range. We suppose species is characterized by high size variability, not following Bergmann’s or Murphy’s rules. Preliminary, distinct size differences have been registered in the eastern and southern edges of the distribution range, with these populations having largest individuals according to average body and skull size. In terms of tail length and condylobasal length of the skull, Lithuanian mice on the north-western edge of the species range are among the largest, but in terms of body weight, body length, zygomatic skull width and the length of maxillary toothrow, adult A. uralensis from Lithuania are small and correspond to those from populations on the western edge of the range. The relative skull width (ratio of zygomatic skull width to condylobasal length) of Lithuanian A. uralensis is the smallest across the entire range. In A. uralensis from Lithuania, sex dimorphism is weakly expressed, with hind foot length and postorbital constriction larger in adult males, while the height of the mandibula and length of the mandibular diastema is larger in adult females. Juvenile and subadult A. uralensis from Lithuania differ in body weight, but not in size.     

Confirmed occurrence of the Cusk-eel <Emphasis Type="Italic">Ophidion barbatum</Emphasis> (Osteichthyes: Ophidiidae) from the Coast of Tunisia (Central Mediterranean)

This paper reports the second record but also the first substantiated record of cusk-eel Ophidion barbatum (Linnaeus, 1758) from the northern coast of Tunisia, 168 mm in total length and weighing 18.3 g. The specimen is described including morphometric measurements and counts. Differences from its close relative species O. rochei (Linnaeus, 1758) are pointed out that confirm the occurrence of O barbatum in the Tunisian waters. This finding constitutes the northernmost extension range of the species in the area.     

Changes in size of Baltic field voles over the last 50 years: are they really shrinking?

Using museum materials and recently trapped specimens of field voles (Microtus agrestis (Linnaeus, 1761)) from Lithuania and Estonia, we assessed temporal and latitudinal trends in body and skull size, comparing the periods 1980–1996 and 2014–2016. We measured four body and 23 skull characters, size-adjusting them using the geometric mean procedure. A pronounced decrease in the size of M. agrestis was noted in Estonia, where 23 out of 27 adjusted body and skull characters had decreased by up to 21.9%, with only the tail length, hind foot length, maximum height of mandibula excluding coronoid process and coronoid height of mandibula increasing significantly. Decreases were less marked in voles from Lithuania – most pronounced were a 6.1% decrease in adjusted body length, an 11.6% decrease in adjusted length of the braincase, a 3.85% decrease in the breadth of the braincase, measured at the widest part, a 2.9% decrease in condylobasal skull length and a 2.2% decrease in the height of the braincase. The coronoid height of the mandibula of Lithuanian individuals showed an 8.4% size increase. In both countries, the confounding effect of sex on the size changes of M. agrestis from 1980 to 2016 was much smaller than the effect of time period. Concluding, voles in Estonia became significantly smaller, while changes in the measured characters in Lithuania were heterogeneous.     

Geography of sexual dimorphism in the tooth size of the red fox Vulpes vulpes (Mammalia, Carnivora)

Geographic variation in sexual dimorphism of tooth size was assessed for the red fox Vulpes vulpes (Linnaeus, 1758) across the whole northern range of the species. Twenty-one measurements of tooth size and skull length were taken from 2849 specimens (1577 males and 1272 females) originating from 12 Nearctic and 25 Palearctic localities. The index of sexual dimorphism was calculated as a quotient of the mean measure of certain characters in males by the respective mean in females ( M _m/ M _f). In the whole range, the males were larger than females and mean dimorphism index of tooth size ranged from 1.01 to 1.06. On average, the tooth measurements in males were 3.6% larger than in females. The highest dimorphism was observed in the canines. Dimorphism of tooth size was higher in the Palearctic than Nearctic. Statistically significant differences between regions were found for lengths of C¹, C₁ and M₁. In the Palearctic, higher values of the dimorphism indices were observed particularly in the southern parts of the Eurasian range of the red fox and in Great Britain. For a few metrical traits, sexual dimorphism indices presented significant relations to some geo-climatic variables. The geographic pattern of size dimorphism in the red fox seems to be shaped by sexual selection, intraspecific and interspecific competition and population density.     

Feeding behaviour of Black Sea bottom fishes: Did it change over time?

This study was designed to improve knowledge in feeding behaviour of the round goby (Apollonia melanostomus (Pallas, 1814)), the red mullet (Mullus barbatus ponticus Essipov, 1927), the whiting (Merlangius merlangus (Linnaeus, 1758)), the flounder (Platichthys flesus (Linnaeus, 1758)), the sole (Solea solea (Linnaeus, 1758)), the turbot (Psetta maeotica (Pallas, 1814)) and the starry sturgeon (Acipenser stellatus Pallas, 1771) from the north-western Black Sea. Gut content coupled with stable isotope analysis allowed describing food web variations according to species, in two seasons and at two areas located seawards the Danube River. Present results showed that most fishes have likely changed their feeding behaviour compared to past studies from the same area. Trophic niches were reduced and dietary overlap was common, as different fish species consumed the same dominant prey types. Fishes probably adapted their feeding behaviour to the increasingly low biodiversity of the Black Sea communities.