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The influence of some ecological and evolutionary factors on the pattern of dental polymorphism across the geographic range of the arctic fox (Vulpes (Alopex) lagopus) was studied. Dental morphotype characters (groups of morphotypes from A to S) in 12 geographically separate populations of the arctic fox were documented. Two evolutionary trends were observed: (1) simplification of the premolars and lower carnassial (M1), and (2) increased complexity of the upper carnassial (P4), third upper incisor (I3), and third lower molar (M3). Differences in dental morphology among arctic fox populations appear to be largely explained by evolutionary history, presence or absence of competition with the red fox (Vulpes vulpes), and diet, with a lesser influence of geography and climate. With respect to morphology, arctic foxes from the mainland populations of Eurasia and North America, are the most similar, followed by the partly-isolated island populations (Greenland, St. Lawrence Island). The most distinct forms are the arctic foxes from Commander Islands, that exist in permanent isolation.
Temperate amphibians in colder regions are expected to store more energy prior to hibernation for successful overwintering and subsequent spring breeding. We tested this prediction on a capital breeding species — Rana chensinensis — using samples collected from 27 populations across 1200-km latitudinal (33.6–4.2°N) and 1768-m (112–1880 m) altitudinal gradient in northern China. Our data showed that frogs from colder regions (high latitude or altitude) had relatively heavier liver and fat bodies than those from warmer regions, but that the weight of carcasses tended to become smaller. The greater pre-hibernation energy reserves in colder regions could be an adaptive response to the longer and colder winter period, whereby meeting the energy demands for overwintering, and the subsequent energy requirements of reproduction in the spring.
Knowledge of badger density is important for their conservation especially in areas with low badger densities. Therefore, we aimed to build a simple model to estimate badger density in northern Europe on the basis of habitat characteristics. A radio-tracking study in southern Finland showed that habitat structure of the landscape affects home-range sizes of northern badgers. The data collected from the literature indicate that badger density and home-range size correlate negatively but the relationship was non-linear, with highest densities and smallest home ranges in England. Consequently, badger density can be estimated on the basis of habitat characteristics of the area: density is higher when the proportion of mixed forests is high and that of large spruce forests low and vice versa. Because other factors, such as hunting and predation may be involved, density values should be treated as rough estimates of the density in different landscapes in Finland.
Knowledge of the diet selection by coexisting herbivores is of prime importance in order to draw guidelines for livestock management alongside wildlife conservation. In this study, diet selection by coexisting cattle (Bos taurus), feral horses (Equus caballus), European hares (Lepus europaeus) and white-fronted geese (Anser albifrons) was evaluated in coastal grazing lands of the Evros Delta, Greece. Graminoids constituted the primary forage category for all herbivores, since they contributed more than half in the herbivores' diets. Even though legumes and forbs constituted a substantial part of their diets, selection indices of these forage categories did not exceed the value of 1, which indicates significant selection. Halophytes were selected by all herbivores to a much smaller degree than expected in view of their availability. Increasing the abundance, primarily of graminoids and secondarily of legumes and forbs, is expected to benefit all the studied herbivores.
The body condition and haematological parameters of birds are influenced by a multitude of factors. Here we investigated body mass, fat scores, ratio of heterophils and lymphocytes (H/L), red blood cell count (RBC) of reed buntings (Emberiza schoeniclus), expecting differences between spring and summer (different physiological states/energy demands in breeding/post-breeding periods), sexes (different parental duties) and age groups (different experience/social status). Fat scores and size-corrected body mass were similar in all the groups. Adults in spring had higher H/L than in summer, which may have been due to reproduction-related stress or the seasonal elevation of glucocorticoids. The lower RBC and H/L in adults in summer were associated with their complete moult. Lower H/L in adults in summer compared to immatures may have resulted from their lower stress level (greater experience/higher social status) or a complete moult. The H/L ratio was similar in both sexes, despite their different parental duties.
We compared the diet of adult Pampas foxes (Lycalopex gymnocercus) and their cubs in a Pampas grassland area of Argentina by analysing 152 scats (adults: 92, cubs: 60). We used an Index of Relative Importance (IRI) to determine the contribution of prey items to the diet. IRI scores for rodents, hares and birds were higher for cubs, whereas adults consumed grasshoppers and larvae more often than cubs did. Fruits and carrion of ungulates were consumed only by adults. Both the number of items per scat and diet diversity were smaller for cubs than adults. We conclude that the Pampas fox behaves as a typical central place forager, with fruits and insects being probably consumed on the spot (with low foraging costs) and rodents, birds and hares being brought to the den for the cubs.