Arxiu d'etiquetes: threats

Bearded vulture: conservation of a unique bird

Last month a bearded vulture was born for the first time in Spain of parents bred in captivity and reintroduced into the wild. The bearded vulture is the only bird in the world that feeds almost exclusively on bones. Like the Iberian lynx, it is one of the emblematic animals of the Iberian Peninsula and it is endangered, so it is subject to various conservation and reintroduction programs. In this article, we encourage you to find out more about the bearded vulture and the spanish conservation projects.

DESCRIPTION

The bearded vulture (Gypaetus barbatus) is a diurnal bird of prey popularly included in what is called vultures, scavenger and ghoul birds (they feed on dead animals). However, the bearded vulture is quite different from other vultures:

Quebrantahuesos (Gypaetus barbatus) adulto. )Foto de Jose Luis Ojeda)
Adult bearded vulture (Gypaetus barbatus). (Photo by Jose Luis Ojeda)

 

  • It is so highly specialized that 85% of their diet are bones (osteophague) of dead mammals such as wild ungulates (chamois) and domestic cattle (goats, sheep). It can swallow bones up to 25 cm, and if they are too large catches them, rises them to 20-40 m and crashes bones against the rocks into smaller pieces that can swallowIt also uses the same technique to break tortoise shells.
  • It is very large, with a wingspan up to 2.8 meters and a weitgh up to 7 kg.
  • In general it isn’t noisy: it just whistles if it is excited or during the mating season.
  • It hasn’t the typical plucked vulture head. Vultures have a few or no feathers on their heads to maintain an optimum hygiene after putting their head in dead animals. Due to its peculiar diet, the bearded vulture has more feathers on head and neck, with its characteristic beard” below the peak.
  • The plumage is the same for both sexes but changes with age. The typical reddish and yellowish adults plumage is due to their habit of bathing in mud rich in iron oxides, otherwise they will had a white breast.

Fases del plomatge del trencalòs, segons Adam i Llopis (2003). (Imatge de © X. Parellada.)
Plumage phases of the bearded vulture, Adam and Llopis (2003). (Image by © X. Parellada.)

In this video (5 minutes, catalan) you can see bearded vultures in flight, breaking bones, engulfing them, raising a chick in the nest and bathing in mud.

REPRODUCTION

Bearded vultures nests on ledges and natural rock caves in the mountainous and rugged areas where they live. They have stable partner for life from age 7 and the reproductive cycle has different stages:

  • Pre-laying (September to November): nest building (covering it with branches, wool, feathers, bones ), defense of territory and sexual activity.
  • Incubation (December-February): they lay one or two eggs with a time difference of 6 days. Both sexes participate in the incubation for 53 days.
  • Nurturing (March-August): the largest chick kills his brother (fraticidal violence) to ensure survival. Parents provide food and when the chick leaves the nest (June-July), learn from them to find and prepare food until their emancipation.
  • Emancipation (January): displacement (thousands of kilometers) and dating back to the land where it was born to breed (philopatric instinct).

Seguimiento de nidos naturales mediante cámaras. (Foto: FCQ)
Tracking of natural nests with cameras. (Photo: Foundation for the Conservation of the Bearded Vulture)

DISTRIBUTION

Subspecies Gypaetus barbatus meridonalis is distributed by the South and East Africa, while Gypaetus barbatus barbatus by North Africa and parts of Eurasia (see map).

In the Iberian Peninsula is found naturally only in the Pyrenees (Catalonia, Aragon and Navarra). Spain is the European country with more breeding couples registered (about 130, 2014 data).

gypaetus barbatus, quebrantahuesos, trencalòs, berded vulture distribution, distribución
Bearded vulture distribution. In red, areas in which has been reintroduced . (Image by Mario, Wikimedia).

THREATS

Bearded vulture populations are declining. It is ranked globally asnear threatened” in the IUCN Red List and “endangered” in the Spanish Catalogue of Endangered Species. Current threats they face are:

  • Death by poisoning (illegal baits, poisoned animal consumption, consumption of remains of lead hunting ammunition plumbism).
  • Death by electrocution or collisions with power lines and wind turbines of wind farms.
  • Poaching
  • Habitat loss and decreasing of reproductive efficiency because of the humanization of the medium (urbanisation, adventure sports )
  • Reduction of food (cattle in stables, obligation to bury the corpses )

Quebrantahuesos muerto por envenenamiento. (Foto: DARPAMN)
Bearded vulture dead by poisoning. (Photo: DARPAMN)

CONSERVATION IN SPAIN

Due to the limited distribution of populations, their low number and difficulty to colonize new territories, in 2014 thirteen autonomous communities signed a protocol for the recovery of vultures in Spain. The most prominent action of this protocol is to strengthen the National Strategy for the Conservation of the Bearded Vulture in Spain (started in 2000) and the Programme Captive Breeding (2001), with actions such as the revaluation of rural areas, supplementary feeding and support for traditional farming practices. This strategy also involves the reintroduction in historic areas where the bearded vulture has been extinguished:

WHAT IS HACKING?

Hacking or rural upbringing is a technique that involves the release of captive-bred animals in an area that the bird assimilates as its birthplace. If successful, the bearded vulture returns to settle and breed. This technique did not has a conservationist origin, since it was developed by falconers in the Medieval Age. Falconry (hunting with birds of prey) are also currently used for wildlife control at airports or cities.

In falconry hacking consists in lefting in an elevated cage chicks that can feed by themselves. Falconer feeds them without being seen. After a few days they open the cage, using it as a basis for learning to fly. They are still feeding them until they learn to hunt by themselves and leave the cage. The young ones connect the cage as its birthplace so it will always return.

Alimentación de un pollo con un señuelo para evitar el contacto humano. Foto: Fundación para la Conservación del Quebrantahuesos
Feeding a chick with a decoy to avoid human contact and make its life possible in the wild. (Photo: Foundation for the Conservation of the Bearded Vulture)

The center managed by the Gypaetus Foundation is based on the natural breeding, with minimal human intervention. Parents raise and feed their young from the second week of hatching. To monitor the nests a video surveillance system is used.

Since 2006, 31 bearded vultures have been released from captive breeding and each one is tracked by GPS transmitters. Currently 15 individuals are still sending signals (9 were killed and 7 stopped working). As said in the introduction, the good news is that last month was born the first chick result of released individuals (Tono and Blimunda) by hacking technique.

For more information, check out this documentary (in spanish) about the bearded vulture and its conservation (El bosque protector. Fauna amenazada, El Quebrantahuesos, 29 minutes).

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

Nocturnal birds of prey: the barn owl, legends and myths

Nocturnal birds of prey have suffered since a long time ago an unfair bad reputation that has led them in some cases to be persecuted and hated. What are these superstitions? Which is their conservation state? What can you do for them? In this article you will discover owls and the barn owl, Tyto albaand the legends associated with them.

GENERAL CHARACTERISTICS OF NOCTURNAL BIRDS OF PREY

As its name suggests, most nocturnal birds of prey (owls, owls, tawny owls) have nocturnal or crepuscular habits. They are carnivorous, with beaks and claws (two toes forward and two backward) adapted to tear flesh from their prey (small mammals, birds, reptiles, large insects ).

HEARING

Owls usually have a rounded shape and apparent large head, with the face feathers forming the so-called facial disk. The facial disc serves as a dish heading sounds towards the ears. The opening of the ear is large, with a fold of skin (preaural halda), which functions as a pinna and is movable as in some mammals.

Oído de lechuza norteña (Aegolius acadicus). (Foto tomada de Jim McCormac).
Norther saw whet owl ear (Aegolius acadicus). (Photo by Jim McCormac).

The position of each ear is asymmetric in some species (one is higher than the other), so some of them -like the barn owl- can locate prey in complete darkness: an ear perceives sound before the other, so their  brain can calculate the exact place where prey is (directional hearing).

Boreal owl skull, cráneo de mochuelo boreal
Boreal owl skull (Aegolius funereus) where can be seen the asymmetric hearing openings and sclerotic eye rings. (Photo taken of Jim Williams)

EYESIGHT

Owl’s vision is highly developed. Eyes, unlike most birds, are in front position, which allows a perfect estimation of depth and three-dimensional vision. On the other hand, eyes are tubular (not spherical like ours) due to the large size of the cornea and lens, which prevents owls from moving them within their sockets. Also they have a protective bone plate around the eyes (sclerotic rings) that also impede movement. To solve this problem, they are able to turn his head 270 degrees. It can be considered that they see in black and white (they best perceive changes in light rather than colors), the pupil dilates a lot in bad light conditions (iris is hidden by dilated pupil) and they are the only birds in which the eyelid closes up to below. They also have a transparent lid” that moistens and protects the eye, called the nictitating membrane.

Visión lechuza, binocular, vista, búho, razces nocturnas
Binocular vison of a nocturnal bird of prey. Humans have a field vision of 180 degrees, 140 of them binocular). (Image by The Owl Pages)

PLUMAGE

Owls, unlike diurnal birds of prey, have a special flight feathers structure, fringed at the top surface and contours. The friction between them and the air is damped, achieving a spectacular silent flight undetectable by preys.

Pluma de lechuza común y autillo, donde se observan las barbicelas. (Foto tomada de Pedro Montoya).
Barn owl feather (Tyto alba) and european scops owl (Otus scops), (Image taken of Pedro Montoya).

THE BARN OWL

The barn owl (Tyto alba), is unmistakable: it has a very well defined and heart-shaped facial disk. The back is gray with golden spots and fine black and white dots.

DISTRIBUTION AND BEHAVIOUR

The barn owl lives all over the world (except Antarctica, north Europe and most Asia) and don’t build a nest, but lays eggs in tree holes, holes in the rock or human buildings (barns, attics, farmhouses, castles, churches ).

Why the barn owl has this negative reputation that caused their persecution in many parts of the world and in Spain? Causes are diverse, all fed by human fear:

  • They can nest in abandoned or sacred locations as churches (some with their own cemetery).
  • Nocturnal habits
  • They are sendentary, they can stay in the same hunting ground for years until food is scarce.
  • Ghostly appearance due to their colors and smooth and silent flight.
  • By their vocalizations (they have 17 different ones) like human screams and peculiar snorts. Listen to some owls making a defense vocalization in the following video:

THE BARN OWL IN THE POPULAR CULTURE. BELIEFS, SUPERSTITIONS, MYTHS AND LEGENDS

In the Iberian Peninsula was believed that owls drank the oil of the lamps in churches, leaving the Saints in the dark (when the real thieves were sacristans). By landing on lamps or touching them and pouring the oil, it was believed that owls hated light, like evil spirits. In spanish and catalan there are sayings that refer to this myth. They were hunted, killed and hanged above the doors of churches and barns to ward off fire and lightning.

The vocalizations of barn owls are also interpreted as announcements of death, and there is a belief (without basis) that if someone hear an owl for several nights (something not difficult given their sedentary habits) a person suddenly will lose life.

Tyto alba, lechuza común, lechuza de campanario
Barn owl (Tyto Alba). (Photo by Kerkuil André).

In other cultures there are also negative legends about owls: in Africa that are sent by sorcerers to kill people or evil demons announcing disasters, in the Argentine pampas that they are sisters of the devil; in Sicily, death or illness for all these reasons they have been killed and tortured.

However, they can also be a good sign (such as guardians of women who die in Australia), but the best known case is the representation of Athena, Greek goddess of wisdom. Currently still appears as a symbol of many institutions and in Greek euro coins.

Euro grecia, euro griego
Greek euro. (Resource: RTVE)

CURRENT STATUS AND THREATS

Nowadays the barn owl is in a state of decline and with an uncertain future due to changes introduced by humans in rural areas, such as changes in cultivation or use of pesticides and rodenticides, which kill their prey (mice) or indirectly birds themselves. The works and renovations of buildings where they used to nest also interfere with reproduction. They also suffer accidents due to the towers and power lines and are often hit by cars. Canary subspecies (Tyto alba gracilirostris) is disappearing due its habitat fragmentation and the low number of individuals in their populations.

Lechuza muerta
Barn owl in a barbed wire. (Photo by PacoT).

It is listed as Endangered in the Red Book of Birds of Spain and included in the National Catalogue of Endangered Species in the category “Special interest“.

WHAT CAN YOU DO FOR OWLS?

Try to find out about these magnificent birds and make them known to your immediate surrounding, banishing misconceptions, especially if you live near their nesting and feeding areas. If you own crops, try to minimize the use of pesticides: a pair of barn owls hunt in average about 2,000 mice a year, being therefore even beneficial to humans.

If you find an owl or wounded bird, you have to pick it carefully (using a towel or a jacket) to avoid hurt it or being hurt, and leave it in a dark, quiet place inside a box pierced so it can breathe. Do not feed it. Then contact a wildlife recovery centre.

REFERENCES

If you enjoyed this article, please share it on social networks to spread it. The aim of the blog, after all, is to spread science and reach as many people as possible. Feel free to share your experience with birds of prey in the comments below. ¿Do you know someone who still believe in this owl legends?

This publication is licensed under a Creative Commons:Llicència Creative Commons

Licencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional.