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Reports (Research report)
Le blaireau Européen (Meles meles L.). Synthèse des données européennes concernant la sélection des habitats, la densité des terriers et des populations, les territoires vitaux, le régime alimentaire et les cycles d’activités.
Le blaireau Européen (Meles meles L.). Synthèse des données européennes concernant la sélection des habitats, la densité des terriers et des populations, les territoires vitaux, le régime alimentaire et les cycles d’activités.
Abstract : SUMMARY
The European badger (Meles melesL.) is a widely distributed species throughout Europe. Moreover, the knowledge and the monitoring of this species arenot easy due to the difficulty of catching and its nightlife. Badgers havebeen studied since the middle of the 20 th century, particularly by the Englishresearchers, for whom this animal has a particularstatus. In addition to the issue of bovine tuberculosis and the alleged role of badgers in it, badger ethology continues to be studied by many researchers. Over the past twenty years, some syntheseshave been published in the scientific literature: density of burrows in Europe, population trends in England, the Netherlands and Ireland, home ranges and population densities. The related papers are sometimes old and, at present, there is no recent synthesis in French aboutthe ethology of the Eurasian badger.Based on the analysis of approximately 400 references (from the 1930s to the present), this report presents current knowledge on burrows (density, size,...), populations, home ranges, activity cycles and diet. A database has been set up, allowing data mapping at theEuropean scale.oncerning the selection of habitats,the forest landscapes (at least 30 to 50% of forest cover) with many grasslands, extensive pastures, hedges, broadleaved oak stands are the preferred sites to dig burrows. The digging mainly occurs in softly well-drained sandy or silty soils in medium to steeply sloping areas (optimum between 40% and 80%) in various aspects. Burrows are excavated close to the edges of the forests and open areas (optimum distance about 100 m) but far from the human habitations (often more than 300 m). Nevertheless, badgers can also live in town (gardens, wooded parks...). Burrows are more often observed in plains than in mountains (< to 400 m). In Mediterranean areas, the proximity of a water source is also an important factor to explain the location of the burrows (often less than 100 to 200 m). oncerning the size of the burrows, itvaries from few square meters (10 to 20 m²) to many hundreds (> 500 m²). The number of holes increases linearly with the area. For the small setts (< 150 m²), the number of entrances is usually below 10 (between 4 and 6). For the intermediate burrows (150 to 350 m²), the number of holes increases and is often between 10 and 15. For the largest burrows, the number of holes can be largely greater than 30. The main setts are greater than the secondary burrows with a more important number of holes (often between 8 and 10 against 1 to 3 entrances).oncerning the typology of burrows, the generally accepted classification separates the main, annex, subsidiary and secondary burrows. The badgers use large burrows first and foremost. Nevertheless, they can use the other setts during the season or according to the climatic conditions. The use of setts also highly depends on the density and the home range of badgers. Some badgers are "faithful" to a burrow but others can change burrows several dozen times a year (often in spring and summer), resulting in a very short residence time (a few days) in each of them. Compared to external climatic conditions, theburrows are thermally buffered environments (cooler and more constant temperatures) with maximum and constant humidity (100%). Concerning the internal structure, the length of the tunnels corresponds generally to half of the observed surface area: from a few tens of meters for small burrows to several hundred for larger ones. Tunnels are generally dug between 80 TCCC and 100 cm deep and are 30 cm wide and 20 cm high. The number of chambers varies from 1 to 3 for the burrows less than 150 m² but increases to 10 and 20 for the larger ones. In the chamber (area of about 0.3 m²), the litterfall biomass varies from less than 1 to 2 kg (more frequent case) to more than 10 kg. Finally, over time, the status of a burrow can change. For example, loss of a main sett (destruction of the habitat) or transition from a secondary to a main burrow.oncerning the fecundity of females, they are fertile all around the year but there is a peak in mating in winter after calving. Females are generally fertilized by several males. Thus, cubs of the same litter do not always have the same father. Births take place in January or February and cubs usually come out in early April. Mortality before one year is high, often around 50%. Only about 30% of females breed every year and the number of cubs ina litter is generally between 2 and 3.oncerning the sett densities and the dynamic of badgers in Europe, the average density of burrows (all types) is 1.1 per km² with a strong variation according to longitude and country. The highest densities are observed in the west of the Greenwich Meridian (Ireland, United Kingdom, France, and Spain) with average values often exceeding one burrow per km². Moving eastward results in significantly lower densities, often in the order of less than one burrow per 10 km². The trend is the same for main burrows, often with densities between 0.5 and 1 burrow per km² in the Westand well below 1 per 10 km² in the East (European average: 0.54 ± 0.79 per km²). The average badger density is 4.8 badgers (adult and young) per km² but again with a very high disparity according to longitude and country. England is well in the lead with average densities of more than 20 individuals per km². Without English data, the average badger density is significantly lower by 1.8 ± 2.4 individuals (adult and young) per km². The eastern regions have significantly lower densities in the order of 1 badger per 10 km². The European meanfor family clan is 4.6 ± 2.1 individuals (adult and young). Excluding the English data (7 ± 2.5 individuals), the meanis 3.8 ± 1.2 individuals (with 2.5 ± 1 adults) with relatively small variations between countries. Overall, one family clan corresponds to 2 or 3 adults and 1 to 2 cubs.oncerning the annual individual home range(HR), the average is 172± 210ha but with an important variation according to the longitude. The smallest home ranges are observed in England (< 20 ha) and then increase as longitude increases, i.e. eastward. In Central Europe, for example, HRs are often over 500 ha. Large HRs are also observed in arid Mediterranean contexts (Portugal, Spain). HRs also vary according to the ecological context. Thus, the smallest are observed for areas with a greathabitat mosaic (forests, grasslands, pastures...); this trend is particularly visible in Poland and Finland. Females tend to have a smaller home range than males. Concerning seasonal variations, the homerange increases in spring and summer, decreases in autumn (by about 15%); the lowest value being observed in winter with a home range 5 times smaller. With regard to gender differences, the home range of females appears to be highest in summer. For males,it appears higherin spring.or badger weight and diet,the average weight of adult females is 9.9± 2.0kg and 10.9± 2.1kgformales. Seasonal variations are more pronounced for females but, for both sexes, the maximum weight is observed in autumn before the phase of lower activity (winter months).
For females, the weight decreases sharply in spring, most certainly in conjunction with the feeding of the cubs. Badgers are generalist, seasonal opportunistic animals with an extremely varied diet but very often based on earthworms. Thus, it has been defined the "worm nights" characterized by night temperatures above 0°C and by a cumulative rainfall of at least 2 mm in the previous 72 hours. During these "earthworm nights", badgers have a high level of foraging activity. In addition to earthworms, badgers can also eat insects, birds, small mammals, carrots, potatoes, various vegetables, apples, blackberries, plums, bread... depending on the habitat. At the European level, there is a positive correlation between the importance of earthworms in the diet and latitude (35 to 60°N): high consumption of earthworms for latitudes > 45°N also corresponding to increasingly heavy rainfall during the summer. For lower latitudes corresponding to warmer and drier climates, the consumption of insects or reptiles becomes more important.oncerning the daily or seasonal activity cycles, they strongly depend on the solar cycle (day length, photoperiod) and on thetemperature; air humidity, precipitation or soil temperature playing different roles according to the ecological context. In fact, badgers seem to set their activity according to the daily/seasonal solar cycles with an additional effect of temperature. Thus, temperatures that are too low (often below zero degrees) result in a significant reduction in daily activity. On the other hand, "warm" nights are favorable nights that are certainly related to the activity of earthworms in the soil under these conditions. Duringspring and summer, badgers can leave 1 to 2 hours before sunset and return after sunrise. The duration of daily activity is often about 8±2 hours.C
https://hal-agroparistech.archives-ouvertes.fr/hal-03120592
Contributor : François Lebourgeois Connect in order to contact the contributor
Submitted on : Monday, January 25, 2021 - 4:16:13 PM
Last modification on : Wednesday, October 26, 2022 - 8:15:56 AM
Long-term archiving on: : Monday, April 26, 2021 - 7:19:19 PM
Contributor : François Lebourgeois Connect in order to contact the contributor
Submitted on : Monday, January 25, 2021 - 4:16:13 PM
Last modification on : Wednesday, October 26, 2022 - 8:15:56 AM
Long-term archiving on: : Monday, April 26, 2021 - 7:19:19 PM
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