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The Greater Horseshoe Bat (Rhinolophus ferrumequinum) is the largest Rhinolophus in Europe. The main feature of this species is the morphology of the nose, decorated with a horseshoe shaped leaf essential for echolocation. Indeed, the Greater Horseshoe Bats nose emits very powerful signals, inaudible beyond a few meters.
His soft and fluffy coat is brown, tinged more or less with reddish brown on the dorsal (ash grey for youngsters) and the stomach is grey-white to yellowish-white. Its wings wide and strong, can support its slow fluttering flight. At rest, it wraps itself in its wings, hanging on the wall upside down, often leaving out just the end of his nose.
Longevity: 15 to 30 years
Size: 5.4 to 7.1 cm
Wingspan: 33 to 40 cm
Weight: 15g to 34 g
ECOLOGY AND BIOLOGY
The Greater Horseshoe Bat frequents warm areas below 800m altitude. It looks for semi-open landscapes with high diversity of habitats, such as woodlands and hardwood areas grazed by cattle (or sheep).
The hunting ground of the Greater Horseshoe Bat is characterized by wooded corridors, grassland on the edge of woods or hedgerows, and along cliffs located near his place of habitation. Hedges are of particular importance for this species, they concentrate insect prey during periods of strong wind and structure the landscape. They guide the bats through their territory on a dark night. Hedges also allow the Greater Horseshoe Bat to hang from a branch, on lookout, during cold nights or when concentrations of insects are low. During the evening at low height, it uses echolocation to catch prey.
In the Camargue, the hunting grounds are generally in a range of 5 to 8 kms around their breeding area.
The bigger the colony, the further these areas are from the breeding ground. No territorial defence behaviour has been observed.
The surface of the hunting area is around 4 hectares, within which are key habitats used in preference. The choice of hunting technique depends on the landscape structure, temperature and density of insects and is carried out in two ways: either in linear flight or from a lookout point, from a branch under the cover of a hedge.
Their diet varies according to the seasons and the countryside. Generally, it feeds on dung beetles, beetles and moths, but can also consume Orthoptera (grasshoppers, crickets), Trichoptera, Diptera (flies), spiders, etc.. In the Camargue, the wings of dragonflies were found in the guano (droppings) of this species.
Grazing by cattle is very positive for the diversification of vegetation structure it generates, and the presence of dung, which promotes the development of dung beetles.
The Greater Horseshoe Bat is sedentary, and moves between the breeding area, a transit area, and the hibernation ground. The species can usually travel to up to 60 km between summer and winter grounds (known maximum displacement is 320 kms).
In summer it lives in small groups and reproduces in the warm breeding areas. Females settle in the warmth of barns, attics, cellars, old mills, roofs of churches or castles, whether abandoned or maintained.
The transit areas are night shelters, more or less temporary, occupied in the spring and autumn. Their characteristics are still poorly understood.
In winter this bat hibernates from October-November to April in natural or artificial caverns where it is completely dark, with a temperature between 5 ° C and 12 ° C, humidity above 96%, light ventilation and absolute tranquillity: galleries of mines, quarries, caves or cellars. In colonies, the individuals gather together on the ceiling of the cavities to maintain a constant temperature, then they wrap themselves in their wings in the form of a cocoon.
The Greater Horseshoe Bat reaches sexual maturity at the age of 2-3 years. Females form breeding colonies (10 to nearly a thousand adults), often associated with the Geoffroy’s Bat. Gestation lasts between six and eight weeks, with maximum of ten weeks when the spring is particularly unfavourable. From mid-June to late July, they give birth to one young per year. The young will master how to fly in between 19 and 30 days, which allows them to begin to hunt independently while still staying in contact with their mother until the age of six or seven weeks. At 45 days, the young will go up to 1.5 km away and generally reach independence during their second month.
The Greater Horseshoe Bat is a very vulnerable species. Its sedentary lifestyle within its various grounds makes it highly dependent on human activities, and it suffers from the increasing light pollution.
The Greater horseshoe bat population may be threatened by:
- The loss and alteration of breeding grounds(demolition of buildings, modification and toxic treatment with a roof, illumination of churches, modernization of old buildings incompatible with the presence of bats ...),
- The repair, modification or closing of hibernation grounds (caving in mines, untimely visits of caves...),
- The modification and / or loss of hunting grounds(uprooting hedges, monoculture, ploughing of grazing land...),
- Road mortality (collisions with vehicles),
- Chemical treatment of agricultural and forestry plots and treatment of livestock against pests.
DISTRIBUTION AND THE STATE OF THE POPULATION
Globally, the Greater Horseshoe Bat is present throughout the Palaearctic from the Atlantic to the Pacific. Despite its classification category LC ("Least Concern") on the global Red List of Threatened Species (IUCN, 2008), the population of the Greater Horseshoe Bat is declining in some areas.
Source : IUCN (International Union for Conservation for Nature). Rhinolophus ferrumequinum. In : IUCN 2011.IUCN Red List of Threatened Species. Version 2012.1
In Europe, the area of distribution of the Greater Horseshoe Bat has greatly reduced in the northwest over the past century (France, Britain, Germany, Austria), sometimes to distinction (Belgium, Netherlands, Malta). However, signs of stabilization and / or growth have been observed in some countries (Croatia, Great Britain, Romania, Hungary). In reality the real population is unknown, particularly in the Euro-Mediterranean countries.
The Greater Horseshoe Bat figures on the European Red List of threatened mammals in category NT ("Near Threatened") with a declining trend in the population.
In France, a 2004 census (SFEPM, unpublished) counted 19 031 individuals distributed over 290 breeding sites and 43,514 in 1953 hibernation sites, which is relatively large in terms of the European population. However, there are significant regional imbalances.
The evolution of the population is poorly known but assumed to be in decline from local observations. The Greater Horseshoe Bat is therefore included in category "near threatened" by the IUCN Red List of endangered species in France (MNHN France & IUCN, 2009).
In the Camargue, the known breeding population of the Greater Horseshoe Bat (= number of females before giving birth) amounted to 750 individuals in seven breeding areas. There are no known hibernation sites in the Camargue (likely due to the absence of favourable cavities).
The evolution of population across the Camargue is unclear because most of the colonies are recent discoveries (from 2005), so a reliable trend can not be followed. However, there are some elements that underline the precariousness of the colony of Greater Horseshoe Bats:
- Several known colonies in the Provence-Alpes-Côte d'Azur and Languedoc-Roussillon regions have disappeared in recent decades, at least two in the Camargue: in the Salin de Badon area and from a farmhouse in Peaudure,
- A number of colonies in the Camargue are directly threatened in the short term or are vulnerable because they are very accessible.
In the Alpilles, about 150 individuals are divided around about 12 different cavities in the winter. The four cavities assessed within the framework of LIFE hosted 135 individuals, or 90% of the known population of the Alpilles.
From the point of view of reproduction, the situation in the Alpilles needs to be clarified . It is not known where the hibernating individuals come from.
The conservation status of the population of the Alpilles is unfavorable. At the main site, the population has decreased 75% since 1989. At the current rate of decline, the population could disappear by 2017.
In the Gardon gorges, only hibernation sites or swarming (= autumn gathering sites) are known of. The population of the Greater Horseshoe Bat in the Gardon gorges is about 188 individuals in six hibernation sites. The five sites included in the project hosted an average of 170 individuals, or 90% of the population of the Gardon gorges.
It is unclear from where these individuals come from. We assume they are from the Camargue, where the closest large summer populations are situated.
The conservation status of the population of the Gardon gorges looks good, recent counts show a stable population.
For the entire area covered by the LIFE+ Chiro Med program, the size of the breeding population of the Greater Horseshoe Bat is at least 750 individuals (covering the seven known sites grouped in the Camargue). In the rest of the Provence-Alpes-Côte d'Azur and Languedoc-Roussillon regions, the number is 250 individuals in 10 sites (BD GCP, 2008) in Languedoc-Roussillon, there ares 1500 individuals in 12 sites (BD GCLR, 2008) and in Corsica 650 individuals in five sites, or 3,150 individuals in total.
The breeding population in the Camargue represents 75% of the population of the Provence-Alpes-Côte d'Azur and Languedoc-Roussillon regions and 24% of the breeding population in the French Mediterranean.
In terms of hibernation, the Alpilles and the Gardon gorges host an average of 325 individuals in nine sites. These individuals are likely to have come from the Camargue. There are 130 other individuals that hibernate in the rest of the Provence-Alpes-Côte d'Azur and Languedoc-Roussillon region (BD GCP, 2008), 1700 in Languedoc-Roussillon (BD GCLR, 2008) and 500 in Corsica in 2004, a total of 2540 individuals.
Wintering populations in the Alpilles and the Gardon gorges represent 13% of the French Mediterranean wintering population.
The density of the population of the Greater Horseshoe Bat in Camargue is 0.14 ind. / Km ² 2. 5 times higher than those observed elsewhere in Europe: southern England has 0.06 ind. / Km ² (10) and Hungary 0.05 ind. / km ² (11).
In conclusion, this large Mediterranean population is highly threatened today as it was yesterday, despite the interest it arouses. There is full justification for the introduction of a major conservation program.