The Barn Owl is a medium-sized (pigeon-like) nocturnal raptor with a slender body extended by long legs and broad, long wings. The general ...
The Barn Owl is a medium-sized (pigeon-like) nocturnal raptor with a slender body extended by long legs and broad, long wings. The general appearance of the plumage appears quite clear. The upper parts of the body are reddish yellow with marbled grey and pale brown feathers punctuated by small white spots with black tips in the form of droplets.
Barn Owl Presentation
The underside is entirely white with varying degrees of dark brown spotting on the chest and flanks depending on the sex and age of the birds (ROULIN, 1996). The large head is characterized by the presence of a silvery white facial disc surrounded by heart-shaped brown, contrasting sharply with the black eyes.
The beak is yellowish-white, the fingers are grey or yellowish; the nails are brown. Remiges are white and yellowish russet, marbled with grey with some brown bars, russet rectrices crossed out with grey brown with some brown bars, russet rectrices crossed out with grey brown (GEROUDET, 2000). Subspecies guttate is darker, with the upper surface dark grey and the underside orange to reddish-brown heavily mottled with brown.
The facial disc is distinctly reddish tinged. The species has no sexual dimorphism, except for the size which is slightly larger in females.
The Frightfully practices a slow and supple flight often with the hanging legs observed when slowing down or flapping its wings on the spot. As with many nocturnal raptors, the flight is particularly remarkable for its extreme silence (inaudible at over two metres) resulting from the downy structure of the feathers, which allows the Barn Owl to increase its auditory perception (VALLEE, 2003; MULLER, 1999).
Complete molting of the adult occurs between May and November. The first moult of the wings and tail lasts for three years in the young after their first year of life and then takes place over a two-year cycle (GEROUDET, 2000).
The vocal expressions of the Fright Beetle are very varied. The repertoire includes very irregularly paced snoring (high-pitched and whistling in young people) and prolonged whispering. In flight, one notes high-pitched, shrill and trembling cries. The alarm call corresponds to a long, squeaky scream. Both adults and young birds blow and snap their beaks when they are worried (All the birds of Europe,, Jean-Claude Roche, CD n° 3/ track n° 3).
The total length of the body is about 35 cm. Its weight is 290 to 340 g (315 g average) in males and 310 to 370 g (340 g) in females.
There is no resemblance with other nocturnal raptors of the same size that are significantly darker and wear facial masks of different shape and color.
Geographical distribution of Barn Owl
In the World
Represented by 28 subspecies worldwide, the Barn Owl occupies a vast range encompassing warm and temperate regions of the 5 continents (DEL HOYO, 1999). The northern limit reaches 48° north in America. It is not widespread in Asia. The majority of desert areas are avoided.
In Europe
The species breeds commonly throughout Europe, except in Scandinavian countries. Countries to the east of the continent host small populations, particularly Bulgaria, Belarus, Russia and Ukraine (Bird Life International, 2004).
In France
In France, the Alba Subspecies Warbler breeds throughout the country, except in the mountainous areas of the Alps, the Pyrenees, and the Massif Central. Its reproduction is however confirmed up to 1500 m in the High Alps. It appears to be absent or very rare in the Alpes-Maritimes and uncommon in Ile-de-France (DUBOIS et al. 2000). Eastern France hosts the subspecies guttate and all intermediate forms resulting from guttate/alba hybridization. Corsica is inhabited by the subspecies Ernest, which reproduces up to 800 m in altitude, or even exceptionally up to 1200 m.
Protection and conservation statutes
Protected species (Article 1 of the amended Order of 17/04/81), included in Appendix II of the Bern Convention, Appendix II of the Washington Convention and Appendix C1 of the EEC/CITES Regulation.
Biological and ecological characteristics of Barn Owl
Habitat
The Fright Beetle generally lives in open and hedged environments located close to human constructions.
Preferred hunting territories include a high proportion of natural meadows, field edges, hedges or woods as well as fallow land, fallow land and orchards. Inland or coastal marshes and arable farming areas are also frequented. On the other hand, the large forest areas are rarely occupied. Nesting sites and daytime sheds are most often located in the immediate vicinity of people in hamlets, villages and even in the heart of towns, less frequently on cliffs or in wooded areas.
The nest is usually installed in old buildings that provide a minimum of dark space (barns, barns of farm or house barns, churches, castles, pigeon houses) and in cavities (trees, cliffs). Nesting in trees or cliffs is very rare in the northern and eastern regions of France, whereas it appears to be much more frequent on the Atlantic and Mediterranean coasts (MULLER op. cit.). In France, churches (naves and bell towers) are particularly sought-after.
Diet and hunting territory
The Diet of the Barnacle Fowl has been the subject of numerous studies through the analysis of pellets, less often through photographic monitoring. Even if the species proves to be very opportunistic, voles, murids and shrews make up the bulk of its menu (up to more than 95%). In France, voles can represent 50 to 80% of the diet, except in the Mediterranean region where murids (field mice and grey mice) constitute 50 to 90% of the prey consumed. Grey mice can account for up to 90 % of the biomass (CHEYLAN, 1976) and the importance of field mice is increasing in woodlands. The great diversity of other prey represents only 2 to 3% of the diet in eastern France and up to 19% in Roussillon (VALLEE, op. cit.). These are mainly passerines (especially sparrows, starlings and swallows), more rarely insects, bats and amphibians. The daily consumption of an adult barn owl is between 70 g and 105 g of prey (MIKKOLA, 1983).
Reproduction
A monogamous species, the Barn Owl can reproduce as young as one year old but many birds, especially males, wait until they are two years old. Settling on the nesting site in February or March, the pair becomes very active and courtship parades begin.
Schematically, they involve nuptial flights by the male, very noisy sexual pursuits, and offerings. The couple does not necessarily seem to be united for life, but is said to be faithful to the breeding site (VALLEE, op. cit.). The species does not build nests and is content with only rudimentary arrangements. The nest consists of a small bowl dug on a pile of old disintegrated balls.
The volume of the egg-laying is very variable. It reaches 2 to 14 eggs (6 on average) in a study carried out in Burgundy (BAUDVIN, 1986). Incubation by the female alone often begins as soon as the second egg is laid and lasts an average of 32 days (MULLER, op. cit.).
Unlike other nocturnal raptors, the Barnacle Egret can frequently lay two eggs during the year when conditions are favorable. The dates of the first egg laying vary greatly depending on weather conditions. They are spread out from March to June with a peak in April. The second spawning can take place in the same place, before the end of the rearing of the first brood, from the beginning of June to the beginning of August, or even later. A third laying exists but remains exceptional. The young take flight at the age of 8-10 weeks and become independent one month later.
Despite significant annual fluctuations correlated with vole abundance, the productivity of the barn owls appears high (Roulin, 2002). In Alsace and Lorraine, Muller (op. cit.) cites an annual average of 5.2 fledged young per breeding pair over a 15-year follow-up period. Baudvin (1986), in Burgundy, obtains an average number of about 3 young in years with a single brood and 6.5 young in years with the second brood. This high productivity compensates for high mortality, particularly among the young. Life expectancy rarely exceeds 10 years, with records of 18 and 21 years (MULLER, op. cit.).
Ethology
The Barn Owl is not a migratory bird. Adults generally appear to be sedentary, but ergativity may be more or less marked depending on the geographical origin of the birds (Soufflot et al. 2003). Lack of prey is thought to be a factor in the erratic behavior of the Barn Owls. Young birds undertake larger movements, averaging 100 km, but sometimes more than 500 km (MULLER, 1999).
The lifestyle of the Barnacle is clearly differentiated between daytime and night-time activities. During the day, the bird remains hidden, alone or sometimes in pairs, in a shelter (attic, barn, bell towers, tree hole, ivy, conifer, ...) usually sheltered from the weather or from the harassment of other birds. The diurnal activity is mainly occupied by digestion and is reduced to long sessions of sleeping and plumage maintenance.
In some regions or countries, such as the British Isles, the species is commonly observed hunting during the day when the young are reared or in winter when prey is scarce. Hunting activity appears to be intense especially in the early hours of the night, interrupted by periods of rest in the middle of the night, to resume before dawn.
Workforce and development trends
The European status of the Barn Owl was considered to be in decline in the period 1970-1990. Currently, the decline in breeding numbers appears to be more moderate, except in the British Isles, Spain, Italy, Central Europe, and Ukraine (Bird Life International, 2004). However, the conservation status of the species remains unfavorable. The current European population is estimated at 110,000-220,000 pairs. Spain and France host the largest populations with 50,000-90,000 pairs and 20,000-60,000 pairs respectively, followed by Germany and Italy.
Breeding numbers are subject to significant inter-annual fluctuations, mainly due to severe winters causing high mortality. However, these declines are offset by good breeding seasons. The national population currently appears to be stable or slowly declining according to several authors (BIRDLIFE INTERNATIONAL, op. cit; DUBOIS et al. op. cit; VALLEE op. cit; MULLER op. cit.).
Recent regional or departmental enrolments are lacking, only data from the period 1980-1995 are available. Thus, several departments had several hundred pairs: Côte d'Or (1000 to 1500 pairs), Gard (500 pairs), Jura (300 to 600 pairs), Bas-Rhin (200 to 500 pairs) etc.... Normandy had more than 3000 pairs at the end of the 1980s. At the end of the 1990s, the regression of the species seemed to be confirmed in the majority of departments (DUBOIS et al. op. cit.).
Threats and limiting factors
Anthropogenic threats
The previous section dealt with the evolution of the numbers, this one deals with the causes, i.e. the threats to the populations of Barn Owls.
Road collisions
It is the main threat to the Barn Owl, accounting for 50% of the mortality (SETRA, 2006) and also affects other species of nocturnal raptors (long-eared owl, owl owl). A study conducted in the 1980s and 1990s on highways in Champagne-Ardenne and Lorraine (BAUDVIN, 1996) identified the main factors of road mortality in the Barn Owl. Indeed, it can be said that over 10 years of study, a minimum of 0.5 Fright bear killed per kilometer of highway was obtained.
First of all, it is the presence of voles in large numbers that has the greatest influence on the road mortality of the species. In fact, regular maintenance of roadsides results in environments where vegetation is razed. Such environments are on the one hand very favorable to voles and on the other hand, short vegetation is synonymous with good visibility, a characteristic factor of a hunting environment used by the Barnacle Egret.
A second factor is the topography of the communication route in relation to the surrounding environment. The study carried out highlighted the fact that when a highway is cut (higher than the surrounding environment), mortality was significantly higher than when it is level or embanked (lower). Indeed, the birds fly lower in the first case and therefore the probability that they will be struck is much higher.
Secondly, the nature of the surrounding environment is also important. Indeed, mortality is higher when the highway crosses an agricultural landscape than when it is surrounded by a wooded area. This result is due to the fact that the Barn Owl is a species that hunts in the open, flying very low.
Finally, the season also has an influence on the mortality rate since the highest rates were measured in autumn and winter. This observation is logical, as these seasons correspond to the emancipation of the young, the numbers are more numerous and the number of individuals killed is higher.
Lack of favorable nesting sites
Nocturnal raptors do not build nests, so they are dependent either on already existing nests (Middle Duke) or on cavities in trees, cliff shelters or buildings. The Frightowl is well known to occupy human constructions. It nests in barns, attics or bell towers. More rarely it also occupies natural sites, especially cavities in trees in bocage areas. Recently, however, the number of potential sites is decreasing.
The evolution of farm buildings is a first cause, old barns being destroyed or replaced by silos and stables not very conducive to the installation of the barn owl. The number of favorable steeples has also decreased. This is due to the installation of wire netting to prevent the pigeons from settling in. The disappearance of natural sites is due in particular to the regrouping of land in the second half of the 20th century, but also to the systematic uprooting of hedges, making a large number of hollow trees disappear, which are as many potential nesting sites less.
Disappearance of hunting territories
Since the 1950s, the conversion of grasslands to crops has had a detrimental effect on the prey populations of night raptors. In the case of the Barn Owl, the increase in cultivated areas has on the one hand protected voles from predators under high vegetation, and on the other hand the use of phytosanitary products has considerably reduced the numbers. In addition, ploughing also impacts these rodent populations, especially since it is now practiced immediately after the harvest, at the time of the young's flight. These transformations were also accompanied by the disappearance of many fence posts that provided perches for hunting.
Poisonings
The poisoning and intoxication of wildlife has many origins. They can be products used to eliminate "pests" (bromadiolone, chlorophacinone, etc.), products used in agricultural production (carbofuran, furathiocarb, aldicarb, etc.) or products of industrial origin (heavy metals: lead, cadmium ...). Phytosanitary products used in agricultural production have various routes of entry into the environment (sprinkling, aerial diffusion, coating of seeds, dewormers present in dung and manure, etc.). Then, these products end up in water and soil as well as in the food chain where they accumulate. Raptors, located at the top of the food chain, are thus victims of poisoning or intoxication by consuming contaminated prey or corpses. These poisonings can lead to the death of individuals (acute poisoning) but also, and it is difficult to know the real impact, the decrease in fertility or the survival of embryos.
Other anthropogenic threats
In addition to these main factors, there are other threats which, even if their impact on the populations is less, are very real. First of all, it regularly happens that individuals of Barn Owls are trapped in chimneys when they are looking for favorable nesting sites, they enter them, get trapped and end up dying of exhaustion while trying to get out. Cases of drowning in drinking troughs are also noted. The old stone water troughs, with rough edges, have been replaced by metal or plastic troughs or simple baths, with smoother edges, from which the Fright bear can no longer get out when it takes baths to evacuate its parasites, and ends up drowning. Finally, barbed wire fences present mortality risks for nocturnal raptors, especially when they fly at low altitude while hunting. Once caught in the wires, they struggle and often die from their wounds, even if they manage to free themselves. Finally, there are also cases of electrocution and collisions on power lines.
Other Limiting Factors
This section deals with factors that naturally limit the growth of barn owl populations. However, it is these factors that have shaped the biology and ecology of the species throughout its evolution.
Meteorological conditions
It is first of all the snow that most affects the populations of Barn Owls, especially the depth of the snow cover. During severe winters with a thick layer of snow (5-7cm), rodent populations are sheltered from the Barn Owl, which cannot break through the layer. Indeed, some individuals move to find more favorable hunting territories, or others remain on their territory.
Moreover, rigorous winter conditions cause high mortality among the Barn Owl because of its physical constitution, since the species does not have fat reserves, a too long food shortage will have a disastrous effect on the numbers. Moreover, a long-lasting drought or flood situation is harmful for the rodents whose numbers will decrease, and consequently the populations of the Barn Owl will also be affected. To compensate for food shortages, the Barn Owl has a strong reproductive capacity, since it can make two nests in the same year.
Predation
The Weasel is sometimes preyed upon by the weasel, which also lives close to the villages, and can feed on eggs, young, and even adults when the opportunity arises. Unfortunately, most sites are rarely safe from the weasel. In bell towers, there are sometimes sites that are sheltered from this predator, often large churches for example. However, in traditional sites such as classical buildings, predation on broods is important. To stop these problems, especially on the nesting boxes, there are anti-fouling devices.
Competition
There is a competition for nesting sites. Sometimes the Tawny Owl may occupy the same sites as the Barn Owl, which must then find another nesting site, since the Tawny Owl starts nesting before it does. Since this phenomenon is not common, the Tawny Owl is not threatened by this competition.
Barn Owl Knowledge to be deepened
A follow-up that needs to be fleshed out
The study and protection of the Fright Beetle has been carried out for many years in Burgundy and Alsace. Since 2003, the results of the local groups have been summarized in the monitoring notebooks. Each year, about a hundred observers are mobilized in nine regions. However, there are significant gaps in monitoring to determine the abundance and demographic trends of the species. All good wills are therefore welcome to expand this monitoring and protection network.
Historical and cultural aspects
Persecuted for centuries, the Barn Owl was considered a demonic creature (a Barn Owl was considered a bad omen), a healer (eggs and wings were believed to have healing properties), and the tradition of nailing owls to doors was believed to protect against storms and disease.
Subsequently, during the 19th and 20th centuries, the vision of the Frightowl evolved in a positive way with the study of its biology by the first naturalists (Belon, Waterton). Today all birds of prey are protected, persecution has disappeared and the perception of the Barn Owl and night raptors in general is much better than in the past, as shown by the success of the Night of the Owl since 1996, for example.
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